Long-term Plan
for Arctic Environmental Research
Japan Consortium for Arctic Environmental Research

April 2015
(Revised in February 2016)

Preface
The JCAR was founded in May of 2011 and has as many as 384 supporting members as of August 2014. Behind thebirth of the JCAR was the idea of persons involved in Arctic research to develop previous efforts for Japanese researchin the Arctic in a new form. Up to now, many Japanese researchers have visited Arctic. However, although their individual
research abilities are high, results from Japan are often not well remarked in the international movements. As theseresearchers travel to the Arctic as a small group and short timealone, they recognize that continuity from past observations,knowledge of the trends of other researchers, cooperation frameworks, and arrangement are the weak points of Japanese
research. For activities like these, the research is inevitably temporary, and the vision or realization of long-term
observations becomes impossible. The founding of JCAR is expected to improve the exchange information on activities
conducted by every researcher, to have future directions, and to obtain partners for potential cooperative research. The
importance of establishing a long-term vision of Japanese Arctic environmental research within that kind of activity wasconsidered and recommended in a midterm report (August, 2010) after discussion at the 2010 meeting of the Arctic
Research Working Group of the Ministry of Education, Culture, Sports, Science and Technology.
In the fall of 2011, the same year that JCAR was founded, the GRENE Arctic Climate Change Research Project started.
In the following year, 2012, the minimum sea ice extent of the Arctic Ocean in the summer was recorded. The surface
area of snow fall in spring was also a record low, and it was observed that extent of the melt of Greenland ice sheets
expanded to almost the entire ice sheet surface. In March 2013, Japan's “Basic Plan on Ocean Policy” was renewed andattention also focused on the Arctic. In addition, Japanese Master Plan of Large Research Projects regarding the Arctic
were submitted to the ScienceCouncil of Japan. In May 2013, Japan's participation in the Arctic Council as an observercountry was recognized. The activities of the Arctic Council extend through many fields including international relations,environmental issues, and regional administration, but the base of decisions and those activities comes from information
obtained through scientific activities. Regarding the quickly changing Arctic environment and research involving it,
chances are increasing to prepare domestic research activities and appeals for international cooperation. It is important tounderstand the domestic situation in order to answer these problems.
The long-term plan began moving from consideration to implementation in 2013, under the firm commitment of
JCAR's first-term representative, Tetsuo Ohata. The activities of the working group (WG), which was organized to carryout the implementation, undertook the editing work and how to proceed with the work. Along with three general
workshops, discussion sessions were held in consideration of each field and research foundations shared among fields. In
the beginning, there was a concern about inconveniences, such as the length of time needed to write up the long-term
plan, or research ideas being made public. However, over 140 people cooperated with writing up the “Long-term Plan for
Arctic Environmental Research.” Activities for creating this plan progressed with support from the JCAR office andthrough discussion with many researchers involved with the Arctic, from Motoyoshi Ikeda, representative of the WG, aswell as authors of the plan, those involved with peer review and proponents of this work. The writing of this long-termplan in Japan can be considered as the start of new research in the Arctic and an achievement for the system of Arctic
researchers. We would like to show our deep appreciation for those who were involved in creation of this long-term plan.
For this plan, we considered tasks to be worked on over the next ten to twenty years. Many themes from each field
were included. The authors did not just emphasize their own interests and activities, but took a wide perspective andincluded important fields and objectives Japanese researchers should work on. Many of the themes dealt with there do
not end in Japan, but are ideas at a high level of completion which can be proposed internationally.
Changes in nature in the Arctic are happening at a rapid pace. The demands of a changing Arctic environment,
as well as expectations and responsibilities of researchers, are increasing. Phenomena in the Arctic Circle are complex.
Researchers are now expected to look at their own positions relative to the whole, to engage in cooperative research acrossfields, and for researchers of a particular field to learn from content of other fields. This “Long-term Plan for Arctic
Environmental Research” allows researchers in the Japanese Arctic environment to show the challenges and directions of
their own fields as well as to explore relations and movements in other fields. This provides an opportunity to deepen
discussions of Arctic research, and the number of people participating in such research is expected to increase.
Japan Consortium for Arctic Environmental Research,
Chari of steering committee
Hiroyuki EnomotoiTable of contents
Chapter 1: The purposes of the long-term plan report ····················································· 1
Chapter 2: The background and particulars of this report ················································ 2
Chapter 3: Changes in the Arctic environment to date and in the near future ························ 3
Chapter 4: History of Arctic Environmental Research ····················································· 6
Chapter 5: Elucidation of abrupt environmental change in the Arctic associatedwith the on-going global warming ························································ 8Theme 1: Arctic amplification of global warming ························································ 8
Q1: How does horizontal and vertical heat transport from lower to upper atmospheric layers
affect Arctic warming amplification? ·························································· 9
Q2: Is the role of terrestrial snow cover, permafrost, vegetation, and ice sheets important? ····11
Q3: To what extent does the role of sea ice albedo and heat accumulationin the ocean vary seasonally? ································································· 12
Q4: Is it possible to quantify the role of clouds and aerosols? ······································ 14
Q5: Why is Arctic warming amplification occurring, and how uncertain are predictions?
How are radiative forcing and feedback processes changing in the Arctic? ············ 15
Theme 2: Mechanisms and Influence of Sea Ice Decline ················································ 17
Q1: Do changes in wind pattern and sea ice fluidity promote sea ice reduction? ··············· 18
Q2: How does sea ice thermal reduction proceed? ·················································· 18
Q3: How does sea ice reduction influence cloud and cyclones? ··································· 20
Q4: How does sea ice reduction influence the ocean fields? ······································· 20
Decadal strategy in Japan ··············································································· 21
Theme 3: Biogeochemical cycle and ecosystem changes ··············································· 25
Q1: How are the concentrations of greenhouse gases and aerosols in the atmospherechanging? ····················································································· 26
Q2: How are biogeochemical cycles relate to terrestrial ecosystems changing? ················ 29
Q3: What is needed to quantify material transport from land to sea? ····························· 30
Q4: How are biogeochemical cycles that relate to marine ecosystems changing? ·············· 32
Theme 4: Ice sheet / glaciers, permafrost, snowfall / snow cover and hydrological cycle ········ 35
Q1: Will the change in ice sheet and glaciers accelerate? ·········································· 35
Q2: How will the permafrost change interlink with climate change? ····························· 38
Q3. How is the snowfall and snow cover of the Arctic Region changing? ······················· 40
Q4 How will the hydrological processes in the Arctic change? ··································· 41
Theme 5: Interactions between the Arctic and the entire earth ····································· 45
Q1: <Roles of the atmosphere> Is its variability intensified or weakened for example,
the Arctic Oscillation? ······································································· 46
Q2: <Roles of the ocean> Is the water exchange between the Atlantic and the Pacificintensified? Is the deep water formation reduced? Is general circulation modified
in the mid-latitudes? ········································································· 47
Q3: <Roles of the land> How does the variability in vegetation and permafrost haveeffects on carbon flux and the geochemical cycle? How does the variability insnow cover and vegetation have effects on energy and water balances at large scales?
······ 49
Q4: <Roles of the polar upper atmosphere> What effects does the upper atmospherein the polar region have on the lower atmosphere and the whole regionof the upper atmosphere? ··································································· 51
Q5: <Interactions among multiple spheres> Which one is the most influential
on Arctic-global interactions, among the upper atmosphere, the atmosphere,
snow and vegetation on land, or the ocean? ············································ 51ii

Theme 6: Predicting future environmental conditions of the Arctic basedon Paleoenvironmental records ·························································· 54
Q1: How different are the past Arctic amplifications from that of today, and what are
the causes of these differences? ······················································· 56
Q2: How did the Greenland and continental ice sheets change, and what caused them?
What are their relationships with, and contributions to, sea level? ················· 58
Q3: What were the environmental conditions of the Arctic Ocean, especially in termsof sea-ice and biological productivity? ················································ 60
Q4: How different were the terrestrial Arctic paleoenvironmental conditions from thoseof today, and how were they related to atmospheric composition and climate?···· 62
Q5: Were the natural variability on timescales from years to centuries in the Arctic
different from today? What are the mechanisms? ···································· 63【Box 1】Development and interpretations of paleoenvironmental proxies and dating
methods ···················································································· 65
Theme 7: Effects of the Arctic environment on human society ······································· 66
Q1: How do the impacts of climate change, including global warming, appear? ················· 67
Q2: What apparent effects in the terrestrial environment change due to global warming? ····· 70
Q3: What apparent effects in the marine environment change due to global warming? ········ 71
Q4: How do the impact of solar activity and the Arctic upper atmosphere appear
on the human societies? ·································································· 73
Q5: How do the human societies in the Arctic respond to these impacts? ······················· 74
Chapter 6: Elucidation of Environmental changes concerning biodiversity ·························· 77
Theme 8: Effects on terrestrial ecosystems and biodiversity ·········································· 77
Q1: What environmental changes will occur in Arctic terrestrial ecosystems due toanthropogenic factors? ··································································· 78
Q2: How is biodiversity affected? ····································································· 80【Box 2】What is biodiversity? ······································································· 80
Q3: What are the impacts of changes in ATEs on climate and animals? ························· 81【Box 3】Disagreement over scientific names ····················································· 81【Box 4】Changes in reindeer habits ································································ 82【Box 5】Monitoring of waterfowl ·································································· 82
Theme 9: Influence on marine ecosystem and biodiversity ··········································· 84
Q1: Are the ecosystem and biodiversity of the Arctic Ocean significantly affected by
the substance in the atmosphere and from the terrestrial areas? ···················· 84
Q2: How do the biotas of the Arctic Ocean transport substances and alter
their quality? ·············································································· 86
Q3: How are the food chain and changes in ecosystem and biodiversity related
in the Arctic Ocean?. ······································································· 87
Q4: What are the impacts on the ecosystem and biodiversity in the Arctic Ocean
by ocean acidification and denitrification? ············································ 88【Box 6】The pelagic-benthic coupling ······························································· 89【Box 7】Biological hotspots ··········································································· 89
Chapter 7: Broad and important subjects on the Arctic environment ································· 92
Theme 10: Geospace environment ········································································· 92
Q1: What are the effects of the geospace on the upper and lower atmospheres? ················ 93
Q2: What are the effects of the upper atmosphere on the lower/middle atmosphere? ·········· 95
Q3: What are the effects of lower/middle atmosphere change on the upper atmosphere? ····· 96
Q4: How important is the energy flow from the polar region into the middle/low latitudes
through the upper atmosphere? ························································· 98
Theme 11: Interaction of the surface environment changes with solid earth ···················· 100
Q1: What is the interaction between currently active hydrothermal systems of
the Arctic mid-ocean ridges and the marine environment? ························ 101
Q2: How is the Earth deformed by changes in ice sheets? ······································· 102iii

Q3: In the process of forming the Arctic Ocean, how did interactions between
the atmosphere, ice sheets, and the ocean change? ·································· 105
Q4: On time scales of tens of millions, to billions of years, how did the development
process of the Arctic Ocean and the surrounding continents affect changes
in the surface environment? ·························································· 106
Theme 12: Basic understanding on formation and transition process of permafrost ··········· 110
Q1: Permafrost distribution: how is the permafrost in the arctic distributed,
both horizontally (in terms of space) and vertically (in terms of depth)? ········ 112【Box 8】Fundamental understanding of the formation and transition processesof permafrost ············································································· 113
Q2: Permafrost composition: what material does the permafrost consist of,and how heterogeneous is it? ·························································· 115
Q3: Warming and thawing of the permafrost: what is the process, and on what scaledoes it happen? ·········································································· 116
Q4: Permafrost-Atmosphere-Snow-Vegetation system: what is its structure and behavior? ·· 118
Chapter 8: Development of methods enabling breakthroughs in environmental research ·······
Theme A: Sustainable seamless monitoring ····························································
Oceanic monitoring ···················································································
Cryospheric monitoring ···············································································【Box 9】Observations of glacier mass balance ··················································
Atmospheric monitoring ··············································································
Terrestrial monitoring···················································································

121
121
121
124
126
127
129

Theme B: Earth system-modeling for inter-disciplinary research ·································
Q1: What are the development challenges for earth system modeling? ························
Q2: What are the development challenges for atmospheric modeling? ·························
Q3: What are the development challenges for ocean-sea ice modeling? ·······················
Q4: What are the development challenges for land-cryosphere modeling? ····················

131
131
135
136
139

Theme C: Data assimilation to connect monitoring and modeling ································The present state of data assimilation research in the Arctic area ·······························【Box 10】Explanation of data assimilation techniques ··········································
Direction of data assimilation research for the Arctic environment ·····························
Arrangement of basic conditions for Arctic data assimilation research ·························

140
140
141
143
147

Chapter 9: Improvement of Research foundation ························································
Ice-Breaking Observation Vessel ····································································
Satellite Observation ··················································································
Aircraft Observation ····················································································
Oversea Bases for Research / Observation ·························································
Archive System for Data and Samples ······························································
Personnel Training ·····················································································
Promotional System for Research ···································································
Research Equipment by Field ········································································

150
150
152
154
155
158
159
161
163

Chapter 10: Directions and challenges exceeding 10 years ············································· 170
Chapter 11: Reference ························································································· 173
Citation ·································································································· 173
Name List ································································································· 183

iv

15°W

30°W

45°W

60°W

75°W

90°W

0

Atlantic Ocean

105°W
Nuuk

Isua

ICELAND

CircleFaroe
Islands

15°E

Greenland
Sea

Scandinavian
Peninsula Norwegian
Sea

FINLAND

BaffinBaffin Island
Bay

SummitNORWAYSWEDEN

Tromsø

Sankt-Peterburg

Churchill

70°N

Oslo

30°E

Hudson Bay

80°N

Beaufort
Sea

Kara Sea Severnaya
ZemlyaBarrow

Baranova

60°E

TaymyrWest Siberian Plain(Zapadno-Sibirskaya
Ravnina)

Novosibirskiye
Laptev Ostrova
Sea
East Siberian
Sea

Siberia

Yukon
Territory

135°W

Fairbanks

AlaskaShishmaref

150°W

Tiksi

Bering Sea

Central Siberian Plateau(Srednesibirskoye
Ploskogor’ye)

75°E

ChukchiSea

Brooks Range

Novaya Zemlya

RUSSIA

BritishColumbia

Arctic Ocean

Barents Sea

45°E

Resolute

Cambridge Bay

EurekaAlpha Ridge

Moskva(Moscow)

Alert

Ny-Ålesund

Svalbard

120°W

Ellesmere
IslandFram Strait

Longyearbyen
Murmansk

CANADA

Greenland(Kalaallit Nunaat)

Pacific Ocean

Sakha (Caxa)

165°W

Yakutsk
Ust'-Maya

Kamchatka
BaykalSea of Okhotsk

90°E

MONGOLIA

Sakhalin

180

JAPAN
105°E

120°E

135°E

150°E

165°E

Figure 1: A map of Arctic region displaying the main geographical names which appear in thelong term plan. The original map can be downloaded from the JCAR website.

1

Chapter 1: The purposes of the long-term plan report
Terrestrial vegetation supports wild animals, which aresubsequently hunted for food by indigenous people in the
Arctic area. Their traditional culture provided manytreasures to global citizens. The situation is similar for themarine ecosystem where changes in marine biodiversity
and biota are crucial to the ecosystem services which
support residents around the oceans. Both agriculture andfisheries are influenced by the climate, however, there is
one significant difference: i.e., agriculture can be
managed to some extent by maintaining water resources
and choice of crop species, whereas the fishery isdependent on the more complex natural environment, withissues regarding food chains and conflict among different
species.
It should be noted how glaciers, ice sheets andpermafrost are changing, which are unique features in the
Arctic. The rapid degradation of the Greenland ice sheet
during this century is well known, because it is crucial to
future sea level rise. Shrinkage of mountain glaciers varies
from place to place, but the global decrease rate ismonitored only at certain degree. In contrast, thepermafrost is more challenging to monitor, as it also has
an environmental impact when its thawing affects
vegetation and river flows, as well as the release ofgreenhouse gases from decomposing carbon-containing
compounds. The recent increase in Siberian riverdischarges is attributable to an increase in precipitation,and possibly thaws permafrost along the rivers.
In light of the factors mentioned above,
paleoenvironmental research uses analysis of past climatechanges recorded in strata and ice sheets to verify
simulation models for future predictions. An interesting,broader view includes the timing of the development of
the semi-closed Arctic Basin, and its consequences on
climate in the Arctic Ocean and coastal areas. The impactof the upper atmosphere on the stratosphere andtroposphere, in accordance with variable solar activities,
is another example. Not limiting to natural sciences, wider
attention should be directed toward the humanities andsocial sciences: e.g., how to develop collaborative
relationship between the indigenous residents and recent
immigrants. We would expect readers to understand theseconcerns when reading through this report, and generate
ideas for resolving them.

In this plan, Arctic environment specialists aim topresent research direction for the resolution ofenvironmental issues to citizens concerned withenvironmental problems and researchers in various fields.
The primary concern on the environment is global
warming. In particular, it is said that the Arctic is
experiencing warming more than twice as quickly as theglobal mean warming, and dramatic changes in snow andice covers which have been observed are drawing ourattention. It is accepted that despite global warming, someareas sometimes undergo cooling. This is due toatmospheric circulation variability where air temperature
may go up and down from year to year with certain spatial
patterns, while global warming has a time scale in therange of several decades to centuries. Therefore, after
experiencing unusually cold winters, it is understandable
that some doubt the existence of global warming andquestion which direction Japan will take.
Let us move onto the map (Figure 1). By studying theArctic, it has become apparent that during summer, open
water areas exist which were covered by sea ice in a wholeyear until some years ago. The region off the Siberian
coast already experiences only seasonal ice cover. The
future projections indicate that seasonal ice cover will
expand across the entire Arctic Ocean around the middleof this century, although some models suggest this will berather sooner at ten years from now. Whilst simulation
models are necessary for future projections, some may
question their reliability. An even more difficult questionis when the Arctic Sea Route will become substantiallyavailable.
The distribution of vegetation, which is mainly
controlled by climate, will increase under gradualwarming in the middle and high latitude areas. As soil
moisture is crucial, vegetation is dependent on
precipitation and the length of snow cover. There areconcerns that forest ecosystems are not easily transferable
and hence may not be able to follow climate change.
When anthropogenic influences such as deforestation anddevelopment are included, changes in the biodiversity andbiota become difficult to estimate. Human beings keep anissue to preserve biodiversity, which provides thefoundation of terrestrial ecosystem services 1 anddetermines the level of response to environmental change.

Chapter 2: The background and particulars of this report
The long-term plan was proposed in the Basic Policy
Terms of the on-going GRENE Arctic Climate Change
Research Program2 and moreover in the prospectus andagreement of JCAR3. Up to now, no long-term plan has
focused on Arctic environmental research in our country,
hence, it is important to present analyses of the current
status and future direction to be taken. It is no
exaggeration to say that the fact that this long-term plan
has been developed by JCAR has confirmed its existence.
This plan reflects the hopes of the next generation ofresearchers, encouraging forward progress toward
common goals by working together.
It is sensible to select enhanced warming andbiodiversity as the two foci of Arctic environmental
research, since international programs are already in place
to establish the current status, make future projections,and provide proposals for management. The advantage ofJCAR is that it consists of various disciplines, which will
enlighten each other. Therefore, the plan is organizedaround the core subjects, which should be tackled in1
Ecosystem services: Benefits that human being receives from ecosystems: i.e., main ones are food, mental and cultural benefits, and also mitigationof climate and water environment, extending further to oxygen supply and carbon dioxide absorption.
2
GRENE Arctic Climate Change Research Project: project funded for 5 years starting in FY2011 by the Ministry of Education, Culture, Sports,
Science and Technology-Japan (MEXT) within the framework of the GRENE (Green Network of Excellence) Program.
3
JCAR: Japan Consortium for Arctic Environmental Research, a nationwide network-based organization for promoting arctic environmental
research.

２

with global warming enhanced in the Arctic, along withimprovement of their future prediction”. In this objective,
seven themes have been selected such as amplification ofwarming in the Arctic. The second one, research toelucidate “Biodiversity in land and ocean, and also theeffects of anthropogenic environmental change on
ecosystem, not limited to global warming” is divided into
terrestrial and marine themes. The third one covers “Broadand important research on the Arctic environment and its
fundamental information” and includes three themes suchas the geospace environment surrounding the earth. The
fourth objective covers three categories of methods related
to the previous themes, “Monitoring, modeling andintegration of the two, enabling breakthroughs inenvironmental research”.
Many of the environmental changes considered forthese objectives contain complicated interactions among
the atmosphere, ocean, cryosphere, land surface,geochemical cycle, and ecosystem. Hence, this approachactivates inter-disciplinary research. In turn, thisencourages a deeper understanding of each discipline andleads to exploration of unexplained phenomena. The forthobjective encourages breakthrough research from thedevelopment of innovative methods of observation andmodeling, not confined within the improvement oftechniques.
This English version has been prepared in order todisseminate information from us to the international
community. A main purpose is for the Arctic researchcommunity in Japan to present its research direction interms of academic progress. As related discussions were
initiated by ICARPⅢ in 2014, we should not miss theopportunity to use this material to provide input to thediscussions from the Arctic environmental research groupin Japan.

collaboration. Although environmental research has
previously been carried out in the Arctic, global warming
and biodiversity have not been directly focused on.
Therefore, this research may not only enhance theactivities of JCAR as a community, but also provide
important, new information on global warming andbiodiversity. Furthermore, this report includes guidelines
to develop research infrastructure, construction of aplatform for the research and capacity building.
This long-term report is being presented to researchers
who are not involved in Arctic research, to policy makers
who are not specialized in sciences, and to citizens
generally concerned with environmental issues. We wereactually able to document the thoughts and wishes ofArctic researchers, as well as to exchange information
between us so that we may learn from each other’s
activities in various fields, in the process of compiling thisreport. These results provide an important step forward inadvancing future research.
Contents of this report
Several themes have been chosen for each of the four
objectives set here, starting with the changes andvariations in the states to date, alongside a review of theresearch progress. We describe each theme, identifying
gaps in the current understanding, and then suggest
necessary research paths and systems for the next 10 to 20
years. The report is structured so that readers who are notfamiliar with science and researchers who are not
involved in Arctic research, initially read the introduction
about social concerns and then progress further into more
specialized information with the deeper insights.
The four objectives are as follows. The first one, whichis the background for formation of JCAR, is research on“Understanding of the abrupt-complex phenomenon andelucidation of the mechanisms and impacts associatedChapter 3: Changes in the Arctic environment to date and in the near futurecontrast, the stratosphere and upper atmosphere have beenreported their cooling down. When temperature changes
differ between the low- and high-latitudes, and between
the lower troposphere and the upper atmosphere, various
suggestions have been made regarding the feedback to the
low-latitude atmosphere: e.g., how the jet stream aroundthe Arctic changes, and whether meanders tend to growmore or not in the jet stream.
Global warming pushes the northern limit of forests
northward, while permafrost tends to retreat, resulting in
reduction of soil moisture and subsequent forest
degradation in some areas. Once the warming affects
atmospheric circulation through snow cover and thehydrologic cycle, feedback to the land surface should beconsidered, and hence, permafrost degradation andnorthward expansion of forests will vary by region. As aresult of these changes, thawing permafrost may releasegreenhouse gases, while the growing forests will absorb
carbon dioxide. Since soil moisture depends on
precipitation, it is challenging to predict how vegetation
will change. Improved prediction of ice sheet melting
promote the correspondence of social infrastructure by
estimating sea level rise, such as storm surges and lowland
flooding.
The warming also affects the oceans. Cooling becomes

Let us consider the scientific questions for the academic
experts as to how the Arctic environment has changed
over time and will continue to change during this century.
We also introduce progress in research, including thecurrent direction, which has already been addressed. First,
multi-disciplinary issues are described in association withthe objectives of this long-term plan. Most of these issues
are receiving attention from the ongoing GRENE program.
The various factors that cause warming over the global
enhanced in the Arctic and are in turn affected by thephenomenon, are shown in Figure 2, where the warmingis the pivotal point. For example, sea ice reduction andshortened and reduced snow cover occur as a result of
global warming, and then contribute to a reduction inalbedo (reflectance of solar radiation), making feedback
to the Arctic amplification of the warming. Water vapor
increases as a result of the air temperature rise, and hence,
clouds and aerosols (air containing fine particles) increase.
The effects of clouds are dependent on the season, while
they increase the downward longwave radiation except forsummer, contributing to warming at the earth surface. A
future research topic will be to project quantitatively how
much more rapidly the Arctic will warm up in comparison
to the global average.
Greenhouse gases absorb longwave radiation from theearth’s surface, causing the troposphere to warm up. In
3

Figure 2: Crucial changes in the atmosphere, land, cryosphere and ocean, in response to current climate change,along with the effects (one way) and feedback (two ways). Note that while only major changes and interactions are
displayed, other variations may exist. The solid arrows denote confirmed interactions, and the dotted ones denote
more hypothetical ones. Also, the interactions between clouds and global warming can work both ways: e.g., thepresented feedback is important in seasons other than summer, although clouds shield solar radiation and reducesea ice melting in summer. In addition, forest fires occur without global warming, but are becoming more frequent.

environmental variability of the past to enable predictions
for the future, research activities have been focused on ice
cores and marine bottom sediments, as well as exchanging
knowledge with various other fields. A majority of thislong-term plan is based on natural science, however, we
also describe the social impacts of environmental change,and propose methods to respond to changing conditions
with cooperation of the residents who rely on the Arctic
area for their livelihood.
Next, we consider the on-going changes for individual
elements of the Arctic environment and explore someacademic questions. Around the atmosphere, increases inboth longwave radiation from the sea surface and sensible
and latent heat 5 fluxes due to sea ice reduction, willproduce a significant change in the Arctic region. We needto improve the reliability of future prediction for thetransition from stratus to stratocumulus by eliminating

weaker over the Greenland Sea, meaning that deep water
formation under convection is reduced. Therefore, thedriving force of the global conveyor belt4 is weakened, or
the deep water is reduced within the belt, resulting in a
reduction of nutrient upwelling. In the Arctic Ocean andthe surrounding seas, deep convection becomes weaker,
impacting marine ecosystems. However, detailed
investigations are necessary to judge the effects ofchanging conditions on both migratory species and the
opposite ones. Acidification occurring primarily in the
Arctic Ocean will have a large impact on the ecosystem.
The partial pressure of carbon dioxide is determined byocean temperature, inorganic carbon compoundconcentration and alkalinity, and increases under the
global warming, although some unclear elements prevent
prediction of the absorption of carbon dioxide in the ocean.
In order to retrieve useful information from the4
Global conveyor belt: mainly driven by the North Atlantic Deep Water, but also involves other important driving mechanisms. In the Atlantic, thePacific and the Indian oceans, heating and cooling work on the sea surface; salinity is reduced by precipitation and river inflow, and increased byevaporation. As a result, ocean circulation is induced along the meridional (north-south) plane, and hence, the North Atlantic Deep Water near theocean floor in the North Atlantic flows southward in the Atlantic, eastward in the Southern Ocean, and northward in the Pacific, and then, rises to thesurface layer in the North Pacific. It then goes through the Indian Ocean and returns to the Atlantic. This circulation pattern is called the Global
Conveyor Belt.
5
Sensible heat and latent heat: the cold and dry atmosphere takes heat from the ocean. Sensible heat flux is caused by a difference in temperature
between the atmosphere and the ocean. Latent heat flux is induced by evaporation, and then, water vapor returns to the liquid phase and releases heatto the atmosphere.

4carbon dioxide, although the level of fixation is dependent
on the abundance of nutrients. The other functions include
reduction of albedo with the northward expansion of theforest zone, contribution to hydrologic cycle by soil
moisture absorption and evapo-transpiration, and also
arrangement of iron compounds for the marine ecosystem.
Since reduced biodiversity yields vulnerability inenvironmental change, we should focus on exploring thebiodiversity in the high latitude areas relatively behind
mid- and low-latitudes.
Sea ice cover in the Arctic has noticeably reduced due
to air temperature rise and ocean warming. Perennial sea
ice has reduced all over the Arctic, shifting to a seasonalfeature, which has happened most notably over the
Siberian shelves. An increased flow of the warming
Pacific Water into the Arctic Ocean is driving sea ice
reduction. Based on historical records, our specialists
should monitor oceanographic variability in the Pacificsector so that they may explore various components of sea
ice and the processes. The inflow from the Atlantic region
into the intermediate layer of the Arctic Ocean receives
less brine rejection due to less ice formation in the Barents
Sea, and hence, mixes with the Arctic surface water moreeasily. Thus, there is a need to investigate the processes
associated with the seawater influx through the Barents
Sea. Once we attempt a trial experiment to predict sea ice
cover and movement with the navigability of the Arctic
Sea Route in the near future, we will focus on a system touse satellite data and to develop numerical models.
Ocean geochemical cycles and the marine ecosystem
will change, interacting closely with each other.
Expansion of the seasonal ice-covered area tends toenhance the productivity, although it does not necessarily
increase, for example, when circulation of nutrients is
weakened under the freshened surface layer. The species
that have lived in the adjacent seas continue to invade theArctic Ocean, with the distinct possibility that the biota
will be largely transformed. For the Arctic Ocean, whichis under strong influences of river water spreading on thewide continental shelves, the research focuses on material
exchange between the shelves and the basin, and theresultant responses of the ecosystem. As such, it isnecessary to trace the effects of land-origin materials. In
order to monitor the progress of ocean acidification, we
should keep track the areas with under-saturated withcalcium carbonate in the bottom layer of the shelf region
and the surface layer of the basin. Our knowledge of thefood-web and material fluxes from zooplankton to fish
and birds is limited to early summer only, and hence, wehave to build a platform to collect information during theother seasons.
Let us consider the phenomena over time scales longer
than several hundred years. Paleoenvironmental data
provide information on the interactions between
temperature variability and geochemical cycles. Since thepaleoclimate information is applicable to current
environmental changes, the key issue is to develop andoperate a research system under collaboration withvarious academic disciplines. Within the solid earth field,
we focus on the effects of marine hydrothermal activities
and seafloor geodetic on climate change through ocean
circulation. As for the issues on the Greenland ice sheet,
we propose to research the retreat of the grounding line
under the ice sheet due to the sea level rise, and the
response of the ice sheet to its own rapid melting, with aview of potential future problems.

under- and over-estimation of cloud formation in anumerical model. Although increasing greenhouse gases
modify the radiation balance, aerosols form cloud nuclei
and enhance the cloud formation significantly in the
Arctic, therefore we need to identify more appropriate
processes. Atmospheric circulation patterns are modified
by sea ice reduction and snow cover changes with spatial
variability: e.g., the East Asian winter monsoon ismodulated, giving anomalous weather around Japan. Oneof the necessary, but recently developing research topics,
cover interactions of the Arctic area with interannual
variability in the atmospheric circulation in the equatorial
to mid-latitude areas.
As global warming occurs near the earth surface, theupper atmosphere becomes cooler. Monitoring the coolingprovides us with an estimate of the global warming
progress. The ozone layer, in the Arctic in addition to
Antarctic, has been monitored, which highlights the needfor continuous observations with regard to global
warming. Since it has been suggested that solar activities
affect the lower atmosphere, we should attempt toquantify the effects. Space plasma radiates along themagnetic field lines toward the polar region, producing
various phenomena in the upper atmosphere such as
aurora. Monitoring them from the ground helps us to
examine the space plasma environment crucial to the safe
and secure operation of satellites.
Let us consider the terrestrial cryosphere. As for ice
sheets and glaciers, which melt and contribute to a rising
sea level, we will investigate the dynamics and theenergy/mass balance at the surface. Using observational
data and modeling, we will be able to track the massbalance. Although the period of snow cover has beenshortened over the high-latitude regions, snow depth andprecipitation vary greatly in time and space. Therefore, theappropriate method is to combine continuous observations
at stationary points and coverage with satellite data, where
the northward shift and deterioration of forest zone arealso monitored. It is examined quantitatively how much
ice albedo is reduced by microbial effects, along with theeffects of vegetation variability. We can easily imagine
warming around the active layer in the upper part ofpermafrost, while the albedo and heat conduction are
dependent on snow depth in early winter and will
influence the loss near the southern edge. The net
precipitation, which is precipitation minus evaporation, isthought to increase in time and contribute to riverdischarge into the Arctic Ocean. We should consider acomplete picture of the hydrological cycle, by combining
water vapor transport from the sea surface and midlatitudes.
The terrestrial geochemical cycle remains as an
uncertain component in identifying the global carbon
fluxes. In the Arctic area, huge amount of organic matterin permafrost emits carbon dioxide and methane underglobal warming and large-scale forest fires. In addition tocarbon, nutrients and trace metals also flow out to theocean through rivers and due to coastal erosion,
subsequently influencing the primary productivity ofmarine ecosystems. Contributions to monitoring of theenvironment are expected in Siberia, Alaska, Canada andNordic countries.
Terrestrial vegetation supports wild animals, provides
ecosystem services for human beings, and also has thecapacity of feedback to climate change. It is well known
that increased productivity of vegetation fixes more5

be considered just as information transfer to the Arctic
residents, but be pursued in cooperation with them, as anunderstanding between the residents and the researchcommunity, and also on the basis of respect for otherentire human beings.

As for the final issue, the social impacts of Arctic
environmental change are described. In this plan, we list
operation of the Arctic Sea Route, information transfer on
earthquake and tsunami, impacts of terrestrial ecosystemchanges, increasing forest fires, and changes in andmaintenance of marine products. These aspects should not

Chapter 4: History of Arctic Environmental ResearchInternational efforts focusing scientific studies on the
Arctic were a response to the first International Polar Year
(IPY; 1882 - 1883) in the late 19th century. Twelve
countries participated in the IPY and 14 observatories
were opened in the Arctic. In IPY, the main observations
were meteorology, geomagnetism, and the aurora. Japan
voluntarily participated in the IPY, with the advice of
foreign experts, while the Ministry of Agriculture andCommerce Geological Survey and the Navy
Hydrographic Bureau started the geomagnetic
observation. Complete oceanographic observations in the
Arctic began with the Fram Expedition led by Nansen ten
years later (1893-1896). It was still a time of global
exploration, when each country was in competition to
explore the Arctic Sea Route, discover unexplored land,
and reach the North Pole.
Based on the success of the IPY, the second
International Polar Year (IPY2; 1932 - 1933) was
conducted 50 years later; 44 countries attended, including
Japan for the first time. Japan did not have territorial
waters in the Arctic, therefore they started geomagnetic
observations at Sakhalin close to the Arctic, and themeteorological observations at the summit of Mt. Fuji,
which has a climate that is similar to the Arctic. The major
challenges of IPY2 were to observe the ionosphere in
relation to "radio waves forecast" for long-distanceshortwave communication. Japan also participated in thisinternational project by establishing the observatory.
After World War II, the Arctic became the stage of theCold War for the United States and the Soviet Union. The
Arctic Ocean was surveyed by nuclear submarines, sea ice
and ice islands were used as drifting stations, and resource
exploration and cold region research engineering of theGreenland ice sheet and permafrost (which has strong
implications for the military including the resource
exploration) were performed.
Japanese scientists began to conduct research activities
in the Arctic, from the late 1950s. The study of ice coresin the Greenland ice sheet by Ukichiro Nakaya (Hokkaido
University), and meteorological and glaciologicalresearch on the ice islands called ALIS2 and T3 of the
Arctic Ocean by researchers were all carried out as
participations of the United States project. From the late1960s, tracking observations of ice nuclei from over Japan
to Alaska by Nagoya University, permafrost research in
Siberia and Alaska and glacier survey in Alaska by
Hokkaido University were performed by Japanese
research groups. This was during the Cold War era andresearch observations in the Arctic were restricted. In
particular, the door to the Arctic was closed and access todata was limited in the Soviet Union.
A major turning point in the Arctic research was in 1987
when General Secretary Gorbachev of the Soviet Union
6
7

gave his speech at Murmansk. He called for a release of
the Northern Sea Route and the promotion of scientificresearch in the Arctic. A momentum of international
cooperation in the Arctic research grew in response to this,and in August 1990, Arctic countries met in Resolute,
Canada, and installed the International Arctic Science
Committee (IASC). The first meeting of the IASC Council
was held in Oslo in January 1991, where membershipexamination of non-Arctic countries was carried out, andthe six applicant countries, including Japan, were accepted.
This was also a turning point for Arctic research by
Japan. In 1990, the Arctic Environment Research Center
was established by the National Institute of Polar
Research (NIPR). In 1991, along with the cooperation of
the Norwegian Polar Institute, a research station was also
set-up in Ny-Alesund, Spitsbergen, Svalbard, whichstarted observing atmosphere, snow and ice, ocean,terrestrial ecology and upper atmosphere physics.
In addition, in 1990, the Japan Marine Science andTechnology Center (JAMSTEC; currently, Marine-Earth
Science and Technology Organization) in collaboration
with Woods Hole Oceanographic Institution, used theoceanographic vessel of the University of Alaska andautomatic sea ice observing station to perform marine
observations of the Arctic Ocean.
NIPR conducted observations of greenhouse gases at
Ny-Alesund station, biological observations in thepolynya (non-freezing open waters), ice core drilling on
the Greenland ice sheet, the joint observation of theatmosphere by aircraft with the Alfred Wegener Institutefor Polar and Marine Research of Germany, further
aircraft observation of greenhouse gases, aerosols andclouds up to Svalbard across the Arctic Ocean from Japan,
and carbon cycle study of tundra vegetation at Ellesmere
Island in Canada and Svalbard. In contrast, JAMSTEC
commended Arctic Ocean observations using theoceanographic research ship "Mirai" from 1998, with 10
voyages between 1998 and 2013 contributing to theinternational Arctic Ocean observation. From 1997,
Nagoya University began water and energy cycle researchin Siberia over snow cover on frozen ground, by installingthe observation points such as Yakutsk and Tiksi, which
also corresponded to WCRP 6 / GEWEX 7 research
programs. Since 2001, the research project had been
conducted by JAMSTEC, Hokkaido University, Nagoya
University, and Research Institute for Humanity andNature, and the research area has expanded around the
Lena River basin.
In addition, from 1991, the National Institute forEnvironmental Studies (NIES), has continued sustainable
observation of greenhouse gases in Siberia using theobservation towers and aircrafts. Hokkaido University
also began studying permafrost in Siberia and Alaska in

WCRP: World Climate Research Program
GEWEX: Global Energy and Water Cycle Experiment; in 2013 and later, Global Energy and Water Exchanges Project6the 1980s; Kitami Institute of Technology and Hokkaido
University carried out glacier observation of Siberia in the
2000s, and the Forestry and Forest Products ResearchInstitute has been completing a forest survey of Taiga
band. Tohoku University and NIES have also continued
observation of greenhouse gases by commercial airliner
over Siberia. Furthermore, since 1999, JAXA (Japan
Aerospace Exploration Agency) and JAMSTEC began
joint research on the Arctic Research with the Universityof Alaska.
Observational research of the Arctic region by Japan
had been carried out by group-based research, byinstitutions and projects, depending on the decentralized
form; however, we recognize that domestic cooperation
was essential to promote research, and consequently
began Arctic research activities by constituting acommittee by volunteers from 2006. To show our support,
from 2008, the International Symposium on Arctic
Research, which occurs every two years, and the Arctic
session from 2008 at the Japan Geoscience Union General
Assembly.
International research gained momentum around 2000
following sea ice decline in the Arctic Ocean. Between
2007 and 2008, on the 50th anniversary of theInternational Geophysical Year (IGY), with ICSU 8 andWMO 9 as the core, IPY2007-2008 for the Arctic andAntarctic was carried out with promotion of research
activities on observation and data archiving. In order tostrongly encourage research, expansion of theorganization was discussed in the IASC, and the numberof working groups increased since 2011. This gave
Japanese researchers the opportunity to become more
involved in IASC activities.
In 2011, the Ministry of Education, Culture, Sports,
Science and Technology took up the "Arctic Climate
Change" as a part of Green Network of Excellence(GRENE) program. Focusing on the "Rapid Change of the
Arctic Climate System and its Global Influences", a fiveyear plan known as the GRENE Arctic Climate Change
Project commenced. The GRENE Arctic project has the
NIPR as a representative body and participating institutionof JAMSTEC. It is a large-scale project with nearly 300
participating scientists participating from 36 universities
and research institutes across the country.
JCAR was established in May 2011, as a part of the
GRENE Arctic project. In addition to long-term planningon Arctic environmental research, JCAR has discussed theinfrastructure of research and observation, promoted
international cooperation and coordination, anddevelopment of human resources.

89Regarding the sea routes across the Arctic
Ocean, two main routes have been recognizedsince the era of great shipping in the 15th
century: i.e., Northeast Passage is the route
along Siberian coast between Europe and thePacific, and Northwest Passage is the route
along Canadian coast between the Atlantic and
the Pacific. The Northeast Passage is now also
called the Northern Sea Route, which isgoverned by Russia. In this report, we use
Arctic Sea Route and also Arctic Shipping
Route as the entire routes crossing the Arctic
Ocean, including Transpolar Sea Routethrough the middle of the Arctic Ocean.

ICSU: The International Council of Science
WMO: The World Meteorological Organization

7

Chapter 5: Elucidation of abrupt environmental change in the Arctic associated withthe on-going global warming
Global warming is the primary environmental change
in this century, significantly impacting human society andecosystems, causing great social concern. This is why wedescribe the themes in relation to global warming. The key

processes are discussed, with the aim of clarifying
feedback among the various elements of the Arctic
environment. Feedback from ecosystem changes to global
warming is also focused on.

Theme 1: Arctic amplification of global warming
Abstract

and the ice sheet. We considered the effects of snow cover,permafrost, and ice sheet changes with water circulation
changes, and the effects of soil and vegetation alterations
on the atmosphere. Q3 considered the role of sea ice
albedo and heat accumulation in the ocean with seasonal
fluctuations on the Arctic amplification. Q4 discussed thequantitative role of clouds and aerosols, considered to be
extremely uncertain in Arctic warming amplification.
Finally, as an overall summary, we questioned why Arctic
warming amplification is occurring, how uncertain thepredictions are, and what are the changes to the feedback
processes and radiative forcing in the Arctic. We
discussed the quantitative evaluation of the current stateof research and the challenges. Through each question, we
studied from the standpoint of process observation,
long ‐ term monitoring, process models and climate
modeling.
Efforts for more than 10 years have focused on energy
transport in the Arctic region, and continue to examine theinteraction between elements from upper atmosphere to
clouds, aerosols, snow cover, sea ice and ocean middle
layer. In order to develop and use Earth System Models,
not only is the cooperation of modelers in various fields
required, but the planned acquisition of data for model
validation is also needed. As a contribution from ourcountry, we must work with the agency to continue sensor
development and launch satellites in order to develop
satellite observations from the sea ice to the upper
atmosphere. In situ observations of the ocean are key toour contribution and should be repeated systematically.

In the Arctic, several elements in the atmosphere, ocean,cryosphere, land surface and ecosystems are interwoven
in a complex with various feedback effects, resulting in amore rapid temperature rise than in other regions. Thisparticular phenomenon is known as "Arctic warming
amplification". However, our understanding of thequantitative contribution from the individual elements andphysical processes is still insufficient. Therefore, using thefollowing five questions, we proposed a long ‐ term
research strategy for the current and future situation.
Q1: How does horizontal and vertical heat transport
from lower to upper atmospheric layers affectArctic warming amplification?
Q2: Is the role of terrestrial snow cover, permafrost,
vegetation and ice sheet important?
Q3: To what extent does the role of sea ice albedo andheat accumulation in the ocean vary seasonally?
Q4: Is it possible to quantify the role of clouds andaerosols?
Q5: Why is Arctic warming amplification occurring,and how uncertain are the predictions? How areradiative forcing and feedback processes changing
in the Arctic?
In the context of atmospheric circulation, Q1 wasdiscussed by dividing the role of the effects of heattransport from the mid‐latitudes and the role of the upper
atmosphere, how the horizontal and vertical heat transport
in the lower layer to the upper layer of the atmospherewould affect the Arctic temperature amplification. Q2 isrelated to terrestrial snow cover, permafrost, vegetation

Introduction
aerosols; the high albedo snow and ice surface isconsequently replaced by a relatively dark land and sea
surface, and further heating of the near-surface (warming)
occurs. In addition, melting of permafrost leads toemissions of further greenhouse gases. Furthermore,
reduction of sea ice and expansion of open water leads tothe supply of water vapor from the ocean into theatmosphere and increases cloud cover, which then further
melts sea ice. It has been deduced from observation
studies and numerical models that, as a result of thesevarious feedback effects, warming in the Arctic is
amplified; however, our understanding of the quantitative
contribution of individual elements and of the physicalprocesses occurring is still insufficient.
In order to accurately evaluate the environmental
change effects of global warming and resulting impacts onhuman society and to then take appropriate measures withurgency, there is a strong need to understand phenomena
occurring between the elements shown in Figure 3. Thissection discusses questions related to typical components,
such as the atmosphere, ocean and terrestrial elements,

Climate change currently occurring in the Arctic
directly or indirectly affects the natural environment andeconomic activities, not only of the region itself but alsoof areas further afield. These changes are resulting fromglobal warming, in turn resulting from an increase ingreenhouse gases; however, in comparison to lower
latitudes, the temperature rise in the Arctic is high andsubject to the amplification effect (Arctic warming
amplification). However, the mechanism of global
warming amplification in the Arctic is not simple,
involving complex intertwining of various elements in theatmosphere, ocean, snow and cryosphere, land surface,and ecosystems; as a result, we can only observe theresults of interactions between these components.
Figure 3 shows the direction of affect and feedback
effects between each component in the Arctic. Our current
knowledge of the size of each arrow is not very accurate,
and also includes levels of "hypothesis". When "global
warming" occurs in the center, this produces a reduction
in sea ice and snow, increased melting of ice, changes inatmospheric circulation, and changes in clouds and8Figure 3: Potential feedback effects between each element in the Arctic

why Arctic warming amplification is occurring. We also
analyze the current situation and identify a long-term
research strategy.

heat transport in the atmosphere, water circulation on land
and in ice sheet, vegetation changes, and sea ice and ocean.
We then address feedback processes between clouds andaerosols that are subject to high uncertainty, and discuss

Q1: How does horizontal and vertical heat transport from lower to upper atmospheric layers
affect Arctic warming amplification?
2008, etc.). In the case of the latter, Oort (1971) showedseasonal variation using rawinsonde data, and Trenberthand Stepaniak (2003) used re-analysis data sets to show
seasonal variations in and inter-annual variability ofenergy transport; the authors then estimated the individual
contributions of dry static energy, latent heat, and kinetic
energy in stationary and transient components. Hwang etal. (2011) used multiple model results of threedimensional coupled climate models from the intercomparison project CMIP3 to demonstrate that poleward
energy transport in the Arctic decreased, due to thetemperature rise in polar regions. At present, there are few
studies directly dealing with energy transport (heattransport) and these cannot be said to be sufficiently
linked to studies that describe the current state of the
Arctic.

a. The influence of heat transport from mid-latitudes(1) The current state of research
Among the various effects of global warming areseveral changes occurring in the Arctic. Based on
available continuous data obtained by satellite data overthese past 30 years, we know that the sea ice area in the
Arctic Ocean has greatly reduced in extent, as has thesnow cover area; moreover, across a large area of the
Arctic Circle, surface air, soil, and water temperatures arealso exhibiting a warming trend. In addition, a variety ofother changes are ongoing; examples include the releaseof methane (a greenhouse gas) due to melting of
permafrost over Arctic land, increases in the flow of rivers
discharging into the Arctic Ocean, melting of theGreenland ice sheet, shrinking of glaciers and ice caps,
reduction of snow cover area and of its duration, reductionof the amount of ozone in the stratosphere over the Arctic,
and increased occurrence of ocean acidification due to anincrease in atmospheric carbon dioxide. Arctic climatechange might, in reality, be proceeding faster than
predicted by many climate models reported in theIntergovernmental Panel on Climate Change (IPCC)
report.
As in the case of Arctic warming amplification, various
factors of influence have been identified, including theice-albedo feedback14 resulting from a decrease in sea ice
area, changes in albedo due to black carbon, and anincrease in poleward energy transport (Graversen et al.,(2) Future research
In order to understand why warming is enhanced in the
Arctic, and in order to clarify the relationships withmechanisms that underlie global climate change, it isnecessary to understand, not only separate processes, butalso the workings of the entire Arctic climate system,
including by focusing on the role of atmospheric energy
transport within this system. It is therefore important toconceptualize the Arctic atmosphere as one ‘Box’,
analyzing how heat, water vapor, and substances areexchanged between the Arctic and mid-latitudes, and how
9long-term observations of atmospheric density using
orbital data from low-orbit satellites, there appears to havebeen a rapid decrease in atmospheric density in the upper
atmosphere due to air shrinkage caused by cooling of
middle and upper atmospheres. Thus, quantitatively
understanding cooling in the middle and upper
atmospheres can lead to accurate understanding ofwarming in the lower atmosphere. Recognizing the role ofthe upper atmosphere as a mirror of the lower atmosphereenvironment, there is a strong interest in reviewing more
information concerning medium-term and long-termchanges in the mesosphere and upper atmosphere.
However, the absolute amount of available data available
for mid-term and long-term change is insufficient, both interms of observations of noctilucent clouds and in termsof observations of the density of the upper atmosphere.
These discussions are also subject to many uncertainties.
It has been recognized that planetary waves of
tropospheric origin propagate into the stratosphere,changing stratospheric general circulation, and finallyaffecting tropospheric general circulation (e.g., Baldwin
and Dunkerton, 1999). In the mesosphere andthermosphere, various atmospheric waves of troposphericorigin contribute significantly to the formation of thezonal-mean zonal wind and to meridional circulation.
However, it is not well understood whether atmosphericgeneral circulation in the mesosphere and thermosphere iscaused by various waves of tropospheric origin, or, on thecontrary, by effects of the atmospheric vertical coupling
process on the troposphere. Due to global warming,
atmospheric circulation in the troposphere is known to be
subject to large modulations, and as a result, there is
speculation that atmospheric waves propagating verticallyinto the middle and upper atmosphere are also modulated.
With respect to the modulation of atmospheric waves of
tropospheric origin due to global warming, at present little
is known regarding whether the zonal-mean zonal windand meridional circulation in the middle atmosphere areaffected. There is also uncertainty about whether thischange could potentially affect the troposphere.
Ozone variations in the stratosphere are closely related
to the activity of stratospheric planetary waves. However,stratospheric planetary waves are believed to change
significantly as a result of global warming. In addition, it
is very difficult to predict the photochemical reaction
process of ozone destruction from winter to spring, since
it is closely related to associated concentration changes inminor atmospheric constituents and to temperature in thelower stratosphere. For example, in the spring of 2011, theozone hole also occurred in the Arctic, but it is not clear
whether this phenomenon is due to cooling of thestratospherewithincreasing
carbondioxideconcentrations, and it is not known whether theoccurrence rate of the ozone hole will increase in future(e.g., Manney et al., 2011).

atmospheric dynamics are involved. At the same time, itis essential to identify and understand feedback processes,
such as those causing strong global warming. In particular,
there is a need for further comprehensive research on three
aspects: (1) heat, water vapor, and substance exchange
between the Arctic and mid-latitudes, (2) several feedback
processes, and (3) vertical coupling of the mesosphere, thestratosphere, and the troposphere including its boundary
layer in the Arctic.
The key to understanding processes causing abrupt
Arctic climate changes is considered to lie in spatial andtemporal features of variation and change. It is wellknown that various changes have occurred, including adecrease in the area of sea ice and a rise in surface airtemperature, especially in the 1990s. Furthermore, the factthat rapid surface temperature rise was occurring in thiscold region of the Northern Hemisphere during the firsthalf of the 20th century (in the 1920s and 1940s), in
addition to global warming, suggests that there must be an
inherent process causing abrupt climate changes; this isrepresentative of the ice-albedo feedback mechanism of
sea ice. Warming in the Arctic also tends to have aspatially non-uniform pattern, and especially during thefirst half of the 20th century, there was clear warming in
the Eurasian sector. In comparison to other areas of the
Arctic Ocean, seasonal-to-inter-annual variability in theextent of sea ice (from the Barents Sea to the East Siberian
coast) is large; in particular, the Barents and Kara Seas
have the highest levels of heat exchange between
atmosphere and ocean in the Northern Hemisphere.
The Atlantic sector of the Arctic is functioning as anactive area for heat and water exchange between midlatitudes and polar regions, both in the atmosphere and in
the oceans. Variations are strongly controlled by changes
in atmospheric circulation, represented by the North
Atlantic Oscillation (NAO) or the Arctic Oscillation (AO).
On the other hand, sea ice variations in the Barents andKara Seas, through heat exchanges between theatmosphere and oceans, could result in intensification of
the winter monsoon in the Far East via the remoteresponse of the atmosphere. Based on such insights, it isimportant to quantitatively estimate horizontal andvertical heat transport in the Arctic Atlantic-Eurasian
sector, in order to understand Arctic warming
amplification. Also, given such rapid climate change inthe region and its spatial non-uniformity, it is necessary toconsider the potential contribution to horizontal andvertical heat transport of radiative forcing and feedback
mechanisms associated with aerosol-cloud processes. It istherefore important to comprehensively evaluate these
aspects from the viewpoint of climate change in the Arctic.
b. What is the role of the upper atmosphere?
(1) The current state of research
Cooling occurs in the middle and upper atmosphere,
while warming (due to an increase in carbon dioxide) is
dominant in the lower atmosphere. Since atmosphericdensity is low in the middle and upper atmosphere, thischange has been known to appear more pronounced.
Based on cooling of the mesosphere due to an increase incarbon dioxide concentrations, water vapor, and methane
in the vicinity of the mesopause, a recent increase has beenreported in the occurrence rate of noctilucent clouds
generated in summer in the polar mesopause. In addition,noctilucent clouds have also been observed in midlatitudes, where they had not been seen in the past. From

(2) Future research
In the case of the Arctic, it is important to further
develop global observation networks of the upper andmiddle atmospheres and satellite observations. In addition,
multilateral comparisons with observations from midlatitudes and from the Antarctic will contribute to a betteroverall understanding. To more quantitatively reveal the
influence of cooling of the middle-upper atmosphere, it isessential to conduct numerical simulations using
atmospheric general circulation models. It is also10analysis. Moreover, to accurately predict ozone depletioncaused by global warming, it is necessary to use precise
chemical climate models that include photochemical
reaction processes.
Note) See Q4 of theme 5, Q2 and Q3 of them.

important to further improve the accuracy of atmosphericgeneral circulation models, including of middle and upper
atmospheres. In particular, to examine the effects of the
middle-upper atmosphere on the lower atmosphere, it isvery effective to simulate various runs while changing the
top of advanced numerical models, enabling comparative

Q2: Is the role of terrestrial snow cover, permafrost, vegetation, and ice sheets important?
was observed in the summer of 2012. The snow melting
zone and the melting pond of the ice sheet surface
expanded, and microorganisms bred on the surface; bothof these lowered the albedo of the surface, facilitating
melting. Not only have increases in hemispheric specifictemperature, warm air flow, and synoptic weather aroundthe ice sheet been reported, but also the promotion bymelting of processes such as heating by atmosphericradiation due to increased water vapor. The impact offorest fires has also been detected in a decrease inreflectance due to impurities in the ice sheet surface.
Water temperature rise in surrounding waters is believedto increase the instability of the end unit of the ice sheet
and to accelerate glacial retreat. On the other hand,melting water from the ice sheet is also expected toinfluence ocean circulation, and there have been attempts
to jointly study ice sheet and the ocean to detect such
effects.

a. Changes in snow cover, permafrost, and ice sheetswith water circulation changes(1) Current state of researchWith regard to feedback processes of snow and ice onland, permafrost, and ice sheets, and their relationshipwith Arctic amplification of global warming, it isnecessary to first understand the features of each element
efforts are presently underway to understand tracking ofchange processes, and to understand impacts using modelreconstructions. Analysis and model calculations havebeen carried out to understand the promotion of spring
melting by the albedo feedback of snow and ice, andrelating to heat transfer to the surface and atmosphere;
these are based on continuous and wide-scale information
obtained from multi-point observation and satellite datafor heat balance analysis of snow cover. However, there
are many uncertainties concerning start of melting and the
movement of melting water relative to the water cycle.
There is a need to understand basic processes, such as thetransfer of heat conduction and movement of melting
water, through observations, expansion, and maintenanceof monitoring points.
In the high latitudes of the northern hemisphere, it has
been reported that snow cover area in spring has decreased(Derkson and Brown, 2012). However, since winterprecipitation itself has not declined, early spring snowmelt
and discharge are expected. The albedo feedback of snow
cover occurs in spring with the increase in solar radiation,and spring snowmelt is also important for water
circulation. From April onwards, the melting area of thenorthern hemisphere high latitudes extends rapidly
northward to higher latitudes. Satellites are able to observe
the progression of melting and albedo reduction, which
occurs due to an increase in moisture content and snow
grain size. In June, when solar radiation is at its maximum,
snow cover over the land almost disappears, and the stageof ice-albedo feedback moves to the sea ice area of the
Arctic Ocean. During this same period, on land there is
infiltration of snowmelt water underground and runoff
into rivers, while soil temperature also begins to rise.
Reduction in spring snow cover in recent years is expected
to cause modulation of the start and end of snow seasonal
cycles, with a shift in the influence of the timing of albedo.
Melting of permafrost in the permafrost area has not yet
occurred, even if an increase in soil temperature has been
observed. Not only do summer temperatures in the active
layer of surface permafrost cause seasonal melting, butsnow in winter also suppresses ground surface cooling,affecting the increase in soil moisture content promoted
by spring snowmelt. There is a need to observe permafrost
melting promoted by winter temperature conditions andsnow cover. Gravity observations of the satellite GRACE
have indicated mass reduction in Arctic land, withestimates of reductions in ice sheet, glaciers, and ice caps,
and changes in meltwater outflow from the permafrost.
In the Greenland Ice Sheet, melting of the entire surface(2) Future researchSatellite observation is an important information source
for albedo feedback of snow and ice, enablingobservations over a wide area. It is expected to be possible
to acquire observation data to confirm snowfall, snow
cover period, and albedo changes, all of which areimportant in the analysis of ice-albedo feedback. Highly
accurate satellite technologies are being developed tounderstand snow cover and melt regions. However, there
is a need to check accuracy and to improve measurementsof snow water equivalent (see theme A) in each region andduring each time period.
For the snow forecast model, it is desirable to first
improve the prediction accuracy of precipitation /snowfall, then to reduce the uncertainty of snow melting
predictions. Although the observation area of thePrecipitation Observation Mission satellite GPM islimited to south of 65 °N, when combined with groundobservations of snowfall and its strength in thisobservation area (such as in Fairbanks and Yakutsk), it isexpected to produce the basic information necessary tomodel snowfall prediction. In addition, the upper reachesof the basins of large rivers discharging into the Arctic
Ocean are included in the observation area of the GPM.
However, since the estimation error of snowfall bysatellites is large, calibration by local observations will
also be important in future.
With regard to permafrost melting involved in the water
cycle and monitoring of river flow (flooding), there is aneed to develop long-term observation systems. Since ittakes time for data storage, it would be ideal to initiate
observations in a typical region at an earlier stage. Longterm observations of these snow and frozen groundenvironments will depend on Arctic countries and on
international observation network activities; examples
include the installation of bases and the promotion of
intensive observations in a typical region as international
11spring and further non-linear warming amplification canoccur (O'ishi and Abe-Ouchi, 2011). Emission of organiccarbon into the atmosphere by melting of the frozen soil
layer due to warming (see Q2a of theme 1 and theme 3)
further indirectly amplifies global warming. It is therefore
important to quantify vegetation change in the Arctic.
However, there are still uncertainties regarding future
vegetation change and warming amplification in the
Arctic. This is because ground stations are limited and it
is difficult to verify whether model processes can simulate
real vegetation changes in the Arctic. Similarly, it isdifficult to estimate vegetation change and organic carbon
release resulting from permafrost melting.

alliance activities.
When observing impurities, microorganisms, and theparticle sizes that produce snow surface albedo changes,
research into past changes can be validated by analysis ofmulti-point samples and by analysis of snow pits and cores.
There is a need for development of high accuracy
analytical methods and enhancement of monitoring
systems Although regional and time variations in the
distribution of impurities are expected, modeling studies
are needed for transport and deposition processes.
In the Greenland Ice Sheet, melting water flows into thebottom of the ice sheet through Moulin, etc. Dynamic
instability increases by acceleration of basal sliding of theice sheet, with the likelihood of acceleration of ice sheet
mass loss. Retention and re-freezing of melt water also
affects ocean circulation and freezing of surrounding
waters. In future, it will be useful to quantitatively
understand melting and discharge from the ice sheet floor,
and to examine the relationship between atmosphere, ice
sheet, and ocean.

(2) Future research
There is increasing qualitative clarity concerning
individual processes related to vegetation change and theirimpact on climate in the Arctic. Over the time scale of thenext 20 years, vegetation change trends observed so far
are expected to become more pronounced. There are
specific knowledge needs for anticipating change over thisperiod, particularly relating to more long-term
quantification of estimated vegetation change, and related
future contributions to polar amplification; this requires
continuance of existing monitoring, more close
cooperation regimes for ground-based observation,satellite observations, and model research. The need forcooperation across these research areas has been discussed
for more than ten years, and such cooperation has been
advanced through the steady efforts of scientists. However,such problems cannot be expected to be addressed throughrevolutionary improvements, and the simplest method toreach this goal is to continue similar efforts in future. If
we can have inter-comparison and verification of dataobtained with the three research methods - ground-based
observations, satellite observations, and modeling - withmodel data assimilation using satellite data, maintenanceof observation points across a wide-area, and data
integration, this will contribute to improved future
predictive abilities of models. The latter would in turnenable reproduction of the northward expansion of theforest zone and of melting of tundra and changes in related
wetlands, and estimation with high precision of forest
distribution over several hundred years. Attempts at thiskind of cooperation have already begun, and further future
development is expected.

b. Influence of soil and vegetation on the atmosphere(1) Current state of research and problems
In general, plant distribution is determined by external
environmental conditions, such as temperature,
precipitation, solar radiation, and carbon dioxide
concentrations in the atmosphere. Temperature, inparticular, is the most dominant factor in the Arctic.
Boreal forests are located in the relatively warm low
latitudes, while tundra vegetation is formed in relatively
cold high latitudes. Geological evidence indicates thatpast distribution of vegetation was different from thepresent-day, reflecting differences between past andpresent climates. It is important to quantify the change in
vegetation distribution considered to have occurred inassociation with the global warming that is currently inprogress.
In the most recent 20 years, a trend of increasing
vegetation in northern hemisphere high latitudes has been
detected from satellite observations (Tucker et al., 2001).
Although their spatial scales are different, increased
vegetation in the Arctic has been detected by comparing
scenic photography from the past 50 years with the current
situation, which is considered to constitute a response towarming A mechanism that amplifies Arctic warming has
been indicated by model simulation, with increased
vegetation promoting the reduction of albedo andincreasing the absorption of solar irradiance. Furthermore,because the Arctic is also covered with snow, albedo
reduction by vegetation promotes early snowmelt in

Q3: To what extent does the role of sea ice albedo and heat accumulation in the ocean varyseasonally?
It is to be expected that the Arctic has warmed in
response to increases in global warming. The reason forthe high temperature rise (in comparison with otherregions) is ice-albedo feedback. With reference to Figure
4, we interpret the effect of the process related to the ocean,and present a direction for possible quantification.

a. Current status of research(1) Quantitative determination of the role of ice
albedo10 and surface ocean (see theme 2)
A phenomenon has been deduced from the past, in which
albedo of sea ice is higher than that of sea water; solar
radiation is hence absorbed more by the ocean due todeclining sea ice cover (Perovich et al., 2007). However,this feedback is directly limited in summer, with part of10

ice-albedo feedback: Based on the fact that the albedo of snow and ice surfaces is much higher than that of vegetation and soil surfaces, positive
feedback that cools (or warms) increases (or decreases) snow and ice surfaces, then albedo increases (or decreases), with solar radiation that isabsorbed by the ground surface reduced (or increased) and further progression of cooling (or warming).

12Figure 4: Potential feedback effects between each element in the Arctic

amplification effect is the result of a coupled system of
atmosphere, sea ice, and oceans.

the accumulated heat transported downward by verticalmixing in autumn, and released from the open water to theatmosphere. Understanding the rate at which accumulated
heat passes the winter is important. In addition, key points
may be whether negative heat accumulation decreases
with respect to the previous year with a reduction in thevolume of sea ice, and whether open water increases
during the next summer. It is also necessary to quantify
heat accumulation in the atmosphere, and it is essential tounderstand difficult-to-observe changes in the ocean
middle layer and in sea ice thickness.
Autumn precipitation may increase as a result of water
vapor emitted from the increased open water area.
Because snow cover will increase albedo, but will reduceheat conduction through sea ice; it is necessary to quantify
the thermal effect, taking into consideration deposition,
melting, and re-freezing of snow. The effects of summer
melt ponds on albedo and heat conduction rely on satellite
data estimates, even though depth is also important.
When sea ice is reduced in extent, seasonal variations in
the melting-freezing of sea ice also increase. As shown in
SHEBA11 , although in many waters, low salinity waterproduced by melting remains in the surface layer, at themargin of the sea ice area and in some areas where
upwelling occurs due to the terrain (such as on thecontinental shelf), the effect of downward movement ofsummer heat by vertical mixing increases; and hence, thismust also be taken into consideration.

(3) Role of inflow from adjacent waters (see theme 5)
High temperature seawater flows in from the Pacific
Ocean through the Bering Strait in summer, and has
played a large thermal role in reducing the extent of sea
ice. As a result, it leads to ice-albedo feedback. Moreover,
the amount of heat storage in the layer deeper than thewinter mixed layer is biennial, and has the effect ofmelting sea ice in spring and summer. If the influx ofPacific water is increased by global warming, this processapplies to Arctic amplification. In particular, since inflow
is affected by an atmospheric fluctuation pattern (dipolemode), whether the pattern is amplified by warming
would be key to estimating Arctic amplification.
(4) Elucidation and understanding of the role of processes,
including in the middle-deep layer (see theme 5)
Sea water of high temperature and high salinity thatflows from the Atlantic circulates in the middle layer ofthe Arctic Ocean and returns to the Atlantic Ocean.
Thermal effects decrease when this water is fully affectedby freezing in the Barents Sea, although it can be easily
mixed with the shallow layer of the Arctic Ocean if this is
not frozen. The rejected salt amount is reduced due toreduced freezing and vertical mixing may hence be locally
activated, also increasing heat transfer to the surface from
Atlantic water. When this process is significant, Atlantic
water circulation may be transformed in the system, to beconsidered a mechanism for horizontal transport of heat tothe surface of the Arctic.
Until now and notwithstanding mixing, only weakwater movement reaches the deep layer from the surface.
On the other hand, when sea ice is reduced to increasenon-uniformity of the horizontal direction, vertical mixing
and water movement may partially occur. In this case, theeffect of heat storage in the deep layer continues at a scaleof 100 years.

(2) Role of interaction with the atmosphere (see theme 2)
A decrease in sea ice enhances heat transfer from theocean to the atmosphere by promoting synoptic-scaleatmospheric disturbances and cloud formation. At thesame time, due to downward longwave radiation fromclouds, the atmosphere supplies heat to sea ice and to theocean. This interaction constitutes positive feedback. It isnecessary to ensure that this is actually occurring, as wellas to attempt quantitative estimation. On the basis of such
results, it is important to produce estimates, as the Arctic

11
SHEBA: Surface Heat Budget of the Arctic Ocean. Arctic Ocean surface heat balance observation project that was operated mainly in the Arctic
Ocean (including the atmosphere) through United States funding in the 1990s. Ice observation sites were accompanied by a Canadian icebreaker for aperiod of one year.

13

patterns, the use of chemical tracers may also be
considered. Satellite observation is useful for capturing(with high accuracy) important melt ponds, as also thestate of the sea, and changes in cloud height.
Also, by using data assimilation and energy analysis,
we attempt to identify key processes for interactions
between surface and middle layers and between middle
and deep layers of the Arctic Ocean.

b. Future research
For surfaces where sea ice is decreasing, it is essential
to monitor inter-annual variability of sea ice thickness andheat exchange with the atmosphere and middle layer. For
the middle layer, long-term monitoring of the movementand diffusion of Pacific and Atlantic water is important, asalso of mixing that extends to deeper layers. In particular,
in order to see changes in middle and deep water velocity

Q4: Is it possible to quantify the role of clouds and aerosols?
a. Importance and current status of research
Aerosols and clouds play an extremely important rolein the Arctic climate. There is as yet inadequately
advanced understanding of complex interactions, since, inprevious studies, observation was found to be insufficientand only a qualitative understanding of individual
processes could be obtained. It is necessary to examineinteractions between various fields, such as therelationship with mid and low latitudes, differences
between both polar regions, and problems within polar
regions. Clouds play a role in climate formation throughthe radiative effect (Curry et al., 1996). Cloud cover acts
to cool the ground surface by reducing solar radiation andalso acts to heat the ground surface by increasing
longwave radiation from the atmosphere. The actions ofboth are opposed but since the season without sunlight islonger at the poles, and since polar regions are covered
with snow, the latter is dominant over the former. Cloud
cover has a feedback effect that causes warming
amplification by downward longwave radiation. As forthe direct effect of aerosols through radiation, the cooling
effect by scattering of aerosols does not contribute greatly
in the atmosphere over the snow surface; however, theheating effect produced by absorption of aerosols such as
black carbon (black carbon aerosol) appears to be
amplified. Aerosols have a variety of effects. These
include climate impacts due to an indirect effect on clouds
by acting as cloud nuclei, through effects on cloudformation and ice nuclei, and by contributing to changes
in snow and ice surface albedo. A quantitative
understanding of these impacts is therefore required.
In the Arctic, because of the uncertainty of cloud
occurrence, the impact of the latter is immeasurable.
There have been no precise observations of the verticalstructure of clouds. In the Arctic, clouds are also importantin terms of their relationship with sea ice. The presence ofcloud cover affects the growth and melting of sea ice.
Similarly, the presence or absence of sea ice affects thestate and occurrence of cloud cover, reflecting theinteraction of clouds and sea ice. Cloud feedback is one of
the most uncertain processes in the polar climate model.
With regard to aerosols that act as cloud nuclei, there is aneed for integrated understanding that takes into accountdifferent scales of polar change; examples include
generation and transport processes due to naturalanthropogenic origins, light absorption processes, andcloud condensation processes. For example, it is importantto evaluate distribution forms, transport processes, andwet deposition processes of black carbon, and to evaluate
the contribution of black carbon to climate change, notonly directly to the atmosphere, but also due tointeractions with the ocean, snow, and ice. Observational

studies on the role of clouds and aerosols are therefore
urgently required. In order to define the radiative effect ofclouds, the cloud phase must be made clear. This refers to,for example, the kinds of particles clouds are made of, theamount of ice particles and water droplets, the size
distribution, vertical profile, generation, growth, andscavenging processes of aerosols, and moisture absorption
characteristics. In the Arctic, mixed phase clouds, where
ice particles and water droplets coexist, are often said tobe seen. Together with the discussion of cloud phase, it isimportant to explain the presence of these clouds andcloud cover. From what is known so far on the basis ofsatellite observations, spring and summer cloud coverappears to have increased.
b. Future research
Conventionally, ground-based observations of clouds
have been conducted visually, and it would be better toreplace this observation method with remote sensing
devices. It is also desirable to understand the macroscopic
distribution and microphysical properties of clouds
through long-term quantified measurements. The cloudradar installed at the Ny-Alesund Station, Svalbard is an
important means of cloud observation in the Arctic, andthis is expected to be utilized through international
cooperation. In addition, even with satellite observations,application of conventional passive observations ofvisible and infrared spectra to the polar cryosphereinvolves difficulties. It is necessary to establish newobservation techniques to be used in combination withactive and passive observation; these include active
observation through new lidar and cloud radar
technologies, and validation of direct observations byaircraft and tethered balloons. One example is the
expected use of the EarthCARE satellite12, to be launchedin 2016 by the Japan Aerospace Exploration Agency(JAXA) in cooperation with the European Space Agency(ESA). It is important to reflect these results in theaccuracy of repeatability of clouds in climate models.
Changes in cloud cover due to the recent decline in sea
ice have been noted. Satellite observations have in fact
shown that the quantity of clouds is increasing along withthis reduction in sea ice (Liu et al., 2012), indicating
positive feedback such that cloud cover is increased byevaporation from open water, with further reduction in sea
ice then occurring as a result of downward longwave
radiation from the cloud, which will enhance cloudformation through further evaporation from open water. It
is therefore important to understand interactions of cloudradiation and sea ice (sea surface) to predict climatechange in the Arctic. A climate model is absolutely
essential for integrated understanding of climate change

12

EarthCARE satellite: Earth Cloud, Aerosol and Radiation Experiment. See Research infrastructure (satellite). Satellite equipped with cloud radar,lidar, radiometer, and image sensors for measuring the vertical distribution and radiative effects of clouds and aerosols.

14

obtained observation data. As a prerequisite, it isnecessary to quantitatively reproduce the distribution ofdust and black carbon (having the potential to become ice
nuclei) in polar regions. From this point of view, rather
than the Gaussian lattice grid model, the size of which isvery different in polar regions as compared to low andmiddle latitudes, would also be advisable to use the global
homogeneous grid model (see theme B).

resulting from changes in these aerosols and clouds.
Although progress to date has allowed the development ofclimate models that explicitly13 represent the interactionof aerosols and water clouds, ice clouds are abundant inpolar regions, and in the case of all current major climate
models in the world, the representation of aerosolinteractions with ice nuclei is still insufficient. In future,
we should strive to better address aerosol ice crystal
interactions in climate models when drawing on newly-

Q5: Why is Arctic warming amplification occurring, and how uncertain are predictions?
How are radiative forcing and feedback processes changing in the Arctic?
to have strong seasonality; solar radiation energy that isabsorbed by the ocean surface through the albedo
feedback resulting from the decline in sea ice in summer
is released from autumn to winter. Arctic warming is also
amplified by the greenhouse effect of low clouds. Thus,
factors that have been indicated as being important are theocean heat absorption process, the inversion layer andstability of the lower troposphere which determines the
air-sea heat exchange, and response characteristics of lowlevel clouds. However, such research is based on modelexperimental results under ideal scenarios, and directcomparisons with observational data have not been made.
It is possible to reduce the uncertainty of warming
predictions using a method to identify the relationshipbetween positive and negative aspects of the
reproducibility of current climates in the multi-model andvariations in future predictions. It is also possible toconstrain the future prediction range based on
observational data. Well-known examples include the useof current seasonal changes, based on the magnitude of theobserved spring albedo feedback, to estimate the size ofthe albedo feedback of the Arctic land in future (Hall andQu, 2006). Similarly, to evaluate the reliability and future
predictions of climate models, there is a method utilizing
Arctic warming amplification that actually occurred in thefar past. This is discussed in Q2 and 3 of theme 6.

a. The importance of research
To understand and predict climate change in the Arctic,
it will be key to understand how radiative forcing willchange through anthropogenic emissions of carbon
dioxide and release of aerosols, and how feedback effects
amplifying or suppressing warming by the climate system
responding to it will function and / or change. As can beseen in Q1–Q4, with regard to the mechanism of Arctic
warming amplification, the contributions of various
processes have been noted. For a thorough understanding,
it is important to systematically and quantitatively
examine individual contributions and interactions
between these processes.
b. Current status of research
There are radiative forcing and feedback processes thathave not been considered or fully quantified in previous
research. For example, light-absorbing aerosols can becited as a typical example of radiative forcing having large
uncertainty. When light absorbing aerosols, such as black
carbon, are deposited on snow and ice surfaces, albedo
reduction occurs, and positive feedback effects produce anincrease in snow surface temperature, accelerating snow
and ice melting. The amount of albedo reduction depends
first on the concentration of light absorbing aerosols, butwith the same aerosol concentration, albedo reduction
increases with larger snow particle size. From theGreenland ice core analysis, black carbon concentrations
after the industrial revolution have been restored, it is
known that the peak was recorded during the first half ofthe 20th century, then dropping to the level of the 1800s.
Growth of snow grain size and expansion of the ablation
area due to warming produce albedo reductions that are
due to light-absorbing aerosols and snow and ice
microorganisms, with this accelerating positive feedback.
The effects of changes in vegetation distribution and of
atmospheric variability higher than the stratosphere have
not yet been sufficiently taken into account in climate
models, particularly with respect to future prediction (seeQ1–Q2). Cloud feedback mechanisms of the Arctic arealso subject to very large uncertainty (see Q4). These
interactions are evidently not well understood.
In climate model experiments, the contribution to
Arctic warming amplification of individual physicalprocesses has been systematically examined. Relatively
simple analysis has been performed, based on the energybalance of the multi-model, and on detailed analysis of asmall number of models (Yoshimori et al., 2014). As aresult, the feedback process of the Arctic has been shown

c. Future research
Climate predictions and sensitivity experiments havealready been initiated, with an Earth system model thatincorporates the "snow albedo physical model"; thealbedo varies as a function of light-absorbing aerosol
concentrations and snow grain size. An example can beprovided from numerical experiments of the spring
subarctic using the Earth system model, incorporating aphysical model of the transport and deposition process oflight-absorbing aerosols and snow albedo. With regard to
the lowering effect of ground surface solar radiation due
to carbon aerosols in the atmosphere, darkening(dimming) has been estimated to be smaller than the snow
albedo reduction effect by aerosol deposition. It will benecessary to promote such model development in future.
In addition, it is also necessary to model albedo reduction
effects of snow and ice microorganisms through fieldobservation, estimating feedback; these aspects are notcurrently being taken into account.
There are still challenges in terms of basic
improvements in reproducibility of numerical models, forexample relating to seasonal changes in sea ice and clouds

13

In the field of modeling, "explicitly" is often used to refer to writing down a process (time change of variables) directly and explicitly in the model
equation.

15

in polar regions. Energy balance estimation andquantification of cloud effects at the ground surface
remain challenging, and it is essential to conduct
evaluation through cooperative observation and modeling.
In addition, and as mentioned in Q3, other importantfactors include sea ice reduction and synoptic-scaledisturbances of the atmosphere, understanding of cloudformation processes, and quantification of theircontribution. Including the effect of decrease in sea ice
and the effects of heat and water transport changes fromlow latitudes, it is important to investigate the cause ofcloud changes.
To understand actual Arctic warming amplification, it
is considered effective to identify the contributions ofindividual processes not only through climate modelexperiments, but also by assimilating observational data.
In addition, the long-term development of sophisticatedcoupled models that are data assimilated is important, asis their application to Arctic warming amplification
research. In addition, it is important to conjoin day-to-day
phenomena and their quantified relative contributions (forexample, the role of cloud formation by synoptic-scaledisturbances and cloud radiation effects in Arctic warming
amplification), and to understand the series of physicalprocesses involved in system response. To understandunderlying individual elements, the role of continued
long-term observation data remains critical.
Changes in vegetation patterns, mineral dust release
related with vegetation change, and other factors such as
the effect of light absorbing aerosols are not uncommon,and change will continue to be significant in future. In
order to introduce elements or processes that have neverbeen significantly taken into account, and to reduce theuncertainty of response characteristics by using observed
data, it is essential to develop, refine, and use the Earthsystem model.
Although Earth system models are mainly referred to intheme B, these models will fulfill a central role in future
prediction. As mentioned in theme 6, to constrain the
climate system response using past Arctic warming
amplification, a valid Earth system model contains allelements that can be considered. Also, as described in Q1,
to consider the effect of the upper layer of the stratosphere,
it is also necessary to consider sufficient resolution andhigher top for models in the stratosphere. It is
indispensable to comprehensively verify air-sea coupledenergy balance processes, from the upper and lower layer
atmosphere to cloud radiation, and from sea ice to ocean
stratification, without relying on data assimilation. The
establishment of an independent Earth system model that
overcomes the current permanent bias is likewise critical.

16

Theme 2: Mechanisms and Influence of Sea Ice Decline
Abstract

using field observations, which is too challenging to beadequately conducted by only one country. The Japanese
research group has obtained many achievements fromship-based field campaigns in the Pacific side of Arctic
Ocean. To continue our international contribution in the
Pacific Arctic region, comprehensive year-long (including
freezing period) measurements are big challenges to fill inblank data. Over recent years, several non-Westerncountries have already built their own icebreakers. Now
we need further efforts to maintain and strengthen thescientific contribution of Japan. Satellite remote sensing
represented by the microwave radiometer can play aleading role in Arctic environmental research by Japan in
the distance from the Arctic. The improvement of
numerical models is expected to provide more quantitative
information on air-sea ice-ocean interactions and watermass transport across the multiple basins. The findings
obtained by such efforts will result in the understanding of
not only physical oceanographic properties but also polar
marine ecosystems.
Over the next decades, we aim to clarify and quantify
the processes on ocean heat transport covering oceaninterior from bottom of sea ice to intermediate waterlayers and on air-sea ice-ocean interactions related tocloud and cyclones. With regard to the characteristics of
sea ice itself, the detailed processes of melt pond
formation and collision among sea ice floes should beanalyzed. For these analyses, operations of an icebreaker
and all weather-type satellite microwave sensors are
essential. We should also develop next-generation sea iceocean models explicitly resolving individual ice floe anddense water plumes so that reliable information can beprovided for vessels sailing through the Arctic Sea Route.

Recent rapid sea ice decline in the Arctic Ocean has
increased social concerns on the possibility of the entire
disappearance of Arctic sea ice in summer. This change isclosely related to the development of a new commercial
sea route and cold winters in Japan. It has therefore
become an important issue, not only for research scientists,
but also for social and economic communities. Theme 2
contains four questions listed below. First, mechanicalfactors on sea ice motion (Q1) and thermal factors on sea
ice growth /melting (Q2) are described to explore
mechanisms of sea ice reduction. Then, influences of sea
ice retreat on atmospheric (Q3) and ocean (Q4) systems
are discussed.
Q1: Do changes in wind pattern and sea ice fluidity
promote sea ice reduction?
Q2: How does sea ice thermal reduction proceed?
Q3: How does sea ice reduction influence cloud andcyclones?
Q4: How does sea ice reduction influence the ocean
fields?
Since the variation in Arctic sea ice is closely related tochanges in wind pattern and sea ice fluidity, we should
persistently examine the atmospheric pressure patterns
most likely to exist under the future climate and efficiency
of momentum transfer among air, sea ice and underlying
ocean. It is problematic to attribute the sea ice decline
mechanisms only to either motion/melting of sea ice or
atmosphere/ocean warming. We should quantitatively
examine various interactions such as the impact of ocean
currents and weather conditions on heat balance at theocean surface.
International cooperation is essential for academic
research on the Arctic Ocean environment, especially

Introduction“Sea ice” is generated by freezing of seawater and isessentially different from “icebergs”, whose source issnowfall over land. Until several decades ago, most areasof the Arctic Ocean were covered with sea ice throughout

the year. Recent observations revealed that the “seasonalice zone” (i.e., the area where sea ice disappears entirely
in summer) was expanding (Figure 5). In 2012, forexample, the minimum sea ice extent in summer was justFigure 5: (left) Arctic sea ice distribution provided by
IARC-JAXA Information System. In 2012, the extent
of summer sea ice (purple) was just 20% of the wintervalue (white).
(top) Schematic image of sea ice variations. Sea ice
forms from sea water cooled to its freezing point andmelts due to solar and ocean heat. Due to wind, mostsea ice is exported toward the North Atlantic.

17

days) and medium-term (several months) predictions, andto provide available information for vessels. It is
important to clarify mechanisms of sea ice reduction
rapidly occurring in the Arctic Ocean and to construct a
sea ice prediction system based on obtained findings.
Based on the prolongation of the open water period, theinfluence of cyclone and wave activities may become aconcern. Accurate forecasts of weather and sea conditions
are thus required. The unusually cold winter weather thathas recently appeared in the mid-latitude zone (including
in Japan) is considered to be a consequence of Arctic sea
ice reduction. It has been suggested that sea ice conditionsin the Barents Sea influence the winter climate in Japan.
Arctic sea ice changes are thus becoming a hot topic, notonly for the natural sciences, but also for social andeconomic communities.

20% of the preceding winter value. This summer value
corresponded to about half of the average in the 1990s.
There is thus certainly a temporal transition from multiyear ice zones to seasonal ice zones underway. The
forthcoming ice-free period will attract social
communities and has been predicted using various
methods. Previous studies indicated that Arctic sea ice
would disappear entirely in summers of the 2020–2040s(Overland and Wang, 2013). CMIP5 produced a wide
range of simulated results. It should be noted that theassumed social and economic scenarios are also subject tosubstantial uncertainties (see also Theme B).
For safe sailing through the Arctic Sea Route (Russian
Northeast Passage and Canadian Northwest Passage), it isnecessary to accurately predict sea ice conditions withinthese passages using a combination of short-term (several

Q1: Do changes in wind pattern and sea ice fluidity promote sea ice reduction?
thinning allows sea ice to flow easily. The “residence time”
of sea ice from its thermal production in the Arctic Ocean
to export toward the subarctic seas will eventually be
shortened. This change results in reduction of multi-year
ice (i.e., positive feedback). In situ data for sea levelpressure and sea ice drift velocity widely obtained by the
IABP enabled monitoring of the relationship between
wind and sea ice motion. However, the setting of such sea
ice buoys has become difficult due to the increase invulnerable sea ice packs. Alternative methods should beconceived of to maintain the same amount of dataacquisition as in the past. The Japanese researchcommunity should also participate in in situ sea ice
measurements and should clarify dynamic processes withsatellite remote sensing and numerical modeling. We
already have the ground work in place. A sea ice model isa powerful tool for analyzing spatial and quantitative
variability. When the horizontal resolution increases to thesame scale of the individual sea ice floe, the formulationof sea ice dynamics should be revaluated. An additional
possible approach is to estimate drag coefficients between
air, sea ice, and ocean using data assimilation methods.
Over the next decades, we aim to 1) estimate dominantpatterns of sea level pressure under future climate
scenarios, 2) perform real-time extensive monitoring of
momentum transfer among air, sea ice, and ocean, and 3)
predict sea ice, taking temporal changes in sea ice motion
into account, on timescales ranging from several days todecades.

Sea ice motion is controlled by wind forcing andinternal stress (collision among sea ice floes). Export ofsea ice from the Arctic Ocean toward the North Atlantic
increased in the early 1990s, following wind patternchanges associated with the Arctic Oscillation (Theme 5).
In the late 2000s, the dipole pattern of sea level pressure(SLP) (high SLP in the Canadian Arctic and low SLP in
the Siberian Arctic) enhanced sea ice export. It isinteresting that cyclonic (anti-cyclonic) wind anomalies in
the central Arctic promote sea ice export toward the North
Atlantic in winter (summer). Under non-uniform windfields and in coastal regions, the collision of sea ice floes
prevents sea ice motion. Recent weakening of sea ice due
to its thinning has increased sea ice fluidity in the wide
area of the Arctic Ocean (Rampal et al., 2011).
Correspondingly, ocean current and ocean heat transport
under sea ice cover have also been intensified (see Q2 forthe relationship between ocean heat and sea ice decline).
The sensitivity of sea ice motion to wind forcing has been
quantified using an index such as wind factor (i.e., ratio of
sea ice velocity to wind speed). To understand dynamic
factors of sea ice reduction, for example, it is important toevaluate how the momentum transfer between air, sea ice,and ocean depends on sea ice thickness and shape.
Sea ice accumulation toward the northern coasts of theCanadian Arctic Archipelago occurs due to the Transpolar
Drift stream and generates multi-year ice regions. In thissituation, sea ice persists even in summer, and sea ice
response to wind forcing is slow. However, sea ice

Q2: How does sea ice thermal reduction proceed?
transfer among air, sea ice, and ocean has been studied fora long time, quantification is difficult due to its complexity(see Theme 1 for efforts using climate model).
Arctic warming is accompanied by enhanced moistureand heat transport from mid-latitudes. We should predict
and verify future changes in Arctic snowfall, which isconsidered to have increased (see Theme 4 for freshwater
cycles). The inflow of warm water masses is listed as an
ocean heat source for Arctic sea ice reduction (Figure 6).
The Pacific-origin water entering from the Bering Strait
becomes warmer due to solar heat absorption over the
Chukchi shelf and intrudes into the subsurface layers of
the Canada Basin. A significant part of the transported
ocean heat probably affects sea ice freezing/melting in

A significant part of the long-term declining trend in
Arctic sea ice is owed to thermal factors, such as increased
summer melting and decreased winter freezing of sea ice.
Recent reports indicate that snowfall decreased in theEurasian continent and increased over the Arctic sea ice,
because of the northward shift of winter storm tracks in
the high-latitude region of the Northern Hemisphere.
Accumulation of snow, which has low thermal
conductivity and high surface albedo, restricts both winterfreezing and summer melting of sea ice. The sensitivity ofsea ice growth to changes in the start period of snowfall
and snow depth is very topical. Melt ponds, with their low
albedo, promote sea ice melting. Even if the relationshipbetween sea ice characteristics and heat/momentum
18

Figure 6: Major Arctic Ocean current.

activates cyclone generation and the inflow of warm air
masses into the sea ice area. Cyclonic wind causes
divergence of sea ice drift and corresponding expansion ofopen water fractions. Such a cyclone-sea ice feedback
process is important. Open water expansion promotes thedevelopment of inertial motion and internal waves.
Strenuous sea ice motion generates turbulent mixing andvertical heat transport in the underlying ocean layers. In
the Pacific Arctic region, there are two warm subsurface
layers whose heat source is solar heat input and Pacificsummer water, respectively. We can therefore propose
another feedback system where ocean heat released due toturbulent mixing contributes to sea ice decrease withenhancement of net sea ice melting. In addition, theupwelling of Atlantic-origin warm water is considered to
be a heat source in the coastal region of the Beaufort Sea.
These thermodynamic processes include multiple
interactions. The spatial distribution of ocean heat content

subsequent years. The Atlantic-origin water flowing into
the Fram Strait and the Barents Sea is closely related toocean heat content and sea ice distribution in the Eurasian
Basin. Atlantic water flows in the wide area of the Arctic
basins on the decadal timescale. In the Canada Basin, theAtlantic water layer is centered at a depth ofapproximately 400 m, so that it plays a minor role inwestern Arctic sea ice.
Thermal sea ice variations are attributed not only tocharacteristics of sea ice floes and global-scaleatmospheric/ocean warming but also to local feedback
systems. Sea ice-ocean albedo feedback provides anexample of important thermodynamic processes (Figure7). Solar heat absorption into the open water fraction
exposed in sea ice zones for some reason promotes lateraland bottom melting of sea ice or reduces freezing,
eventually causing further sea ice decrease.
Ocean surface warming in the marginal ice zone

Figure 7: Examples of Arctic feedback processes between air, sea ice, and ocean. There are threetemperature maximum layers with different heat sources in the Canada Basin. These ocean heat sources
influence sea ice via various processes. The figure on the right shows the vertical temperature profile
observed in the Canada Basin (Jackson et al., 2010).

19

the heat balance between air, sea ice, and ocean. Satellite
data analysis is also useful to widely explore sea ice area,
where ship-based measurements are localized.

derived from solar heat input and warm water intrusion
varies inter-annually (Jackson et al., 2010). To understandthe complicated system of sea ice decline, it is necessary
to simultaneously and quantitatively capture variations in

Q3: How does sea ice reduction influence cloud and cyclones?
gradient across sea ice and ocean surfaces is large. This
extra-tropical cyclone-type structure transports thesouthern warm air mass to the north, and cold air masses
from the sea ice zone to the south. The weather front
passage remains characteristic, with a cloud-precipitation
system as well as winter cloud bands observed in theJapan Sea. This hence indicates that the ocean heataccumulated in summer is efficiently released to theatmosphere during autumn and winter. This type of ocean
heat release is a contributor to polar amplification in
winter.
The increase in cloud fraction from autumn to winterwas shown by radiosonde data of the Soviet Union. At
present, vertical cloud structure data is obtained bysatellite remote sensing, such as CALIPSO and CloudSat.
However, wintertime cloud measurements are still
difficult and a lot of uncertainties remain. The northward
shift of storm tracks enhance precipitation and snowfall
over Arctic sea ice and eventually influence sea ice growth.
Since atmospheric-ocean reanalysis data (such as NCEPCFSR) has recently been made available, analyses ofcoupled systems could take place in future. The impact ofArctic sea ice decline on the climate around Japan is
described in Theme 5.

Exposed open water is a heat source for the atmosphere
over the sea ice area. It was recently reported that wellknown stratus clouds were changing to a stratocumulus
structure due to upward heat input from the ocean surface
during the Arctic summer. Intensified air convection is a
key process. Whereas increase in cloud bottom altitude
reduces downward longwave radiation, poleward
moisture transport accompanied by Arctic warming has an
opposite effect. The cloud effect on heat budgets at the airocean boundary is thus subject to substantial uncertainty.
On the other hand, the reduction in cloud fraction, whichis caused by a structural shift from stratus to stratocumulus,
potentially increases solar heat input into the ocean
surface. However, an original factor for cloud structurechange is upward turbulent heat fluxes with ocean surface
cooling. The variation in net heat budget should be
evaluated using cloud-resolving models, for example. It
has been noted that the trend in cloud fraction differs
among in situ and satellite and reanalysis datasets, anddepends on spatial/temporal scales.
A recent study revealed that such change in cloud
structure was related to cyclone activities (Inoue and Hori,2011). For example, cyclones rapidly develop in themarginal ice zone, where the horizontal temperature

Q4: How does sea ice reduction influence the ocean fields?
between the basin-side westward current and the shelfside eastward current. Such eddy activities induce shelfbasin water exchange. Local monitoring and highresolution numerical modeling are required to estimate
eddy-induced water transport.
Ocean vertical mixing is categorized into convective
mixing due to dense water sinking and turbulent mixing
due to internal waves. The early-winter turbulent mixing
can change the start period of sea ice freezing via ocean
heat release. The frequency and strength of internal waves
are controlled by the vertical profile of water density (i.e.,
stratification). The investigation of seasonal and interannual variability provides useful information forevaluation of sea ice reduction. Constituting a mysterious
phenomenon, several-meter thin layers with uniform
temperature and salinity extending over 1000 km scales
have been observed at depths of 200-300 m. Double
diffusion is considered to be a possible formation
mechanism. Their spreading process, detailed distribution,
and appearance frequency include many uncertainties.
The detection of relationships between microphysics andsea ice reduction would contribute to progress in physicaloceanography.
Under present climate conditions, Arctic Ocean
circulation is controlled by density gradients between lowsalinity Pacific-origin water, high-salinity Atlantic water,
and fresh riverine water. If increases in Pacific watersalinity and decreases in Atlantic water salinity occur ineach upstream region, the mixed water mass would beformed by enhanced vertical convection. To explicitly
reproduce such vertical mixing, horizontal model

Sea ice works as a buffer of motion, heat, andfreshwater between atmosphere and ocean. The responseof sea ice to wind is larger than the ocean surface, so sea
ice motion can intensify ocean currents. On the other hand,ocean currents are weakened in areas where sea ice packs
collide with each other. Wind-driven sea ice motion andocean surface currents depend on shape and drift directionof each ice floe. The momentum transfer from atmosphereto ocean causes vertical mixing in the ocean surface layer
and upward ocean heat transport to the sea ice bottom.
Detailed investigation of such mechanical processes is an
important sea ice-related analysis.
The quantification of heat and freshwater exchanges
due to sea ice growth/melting becomes more important in
the Arctic Ocean, where seasonal ice zones are expanding.
The inputs of freshwater and solar heat after sea ice
melting intensify ocean surface stratification and restrictvertical mixing. On the other hand, open water expansion
accompanied by summer ice reduction favors winter sea
ice freezing and formation of dense water, which is
eventually located at 100–500 m depths within Arctic
basins. As a result, intermediate layers would be occupied
by colder and higher-oxygen water masses. Dissolved
oxygen is closely related to biogeochemical cycles andmarine ecosystems (see also Themes 3 and 9).
The intensified anti-cyclonic Beaufort Gyre is an
example of the combined effect of motion, heat, andfreshwater inputs associated with recent sea ice decline(McPhee, 2013). In the southern boundary of the Beaufort
Gyre, mesoscale eddies with diameters of dozens ofkilometers are generated from horizontal velocity shear
20freezing have also been reported. It is still unknown
whether the Arctic Ocean shifts toward the region of beinga CO2 source or sink. In Japan, there have beeninterdisciplinary collaborations in studies of the Okhotsk
Sea through marine physics, chemistry, and biology. Byutilizing ship-based measurements, satellite remotesensing, and numerical modeling, we should detect key
processes of biogeochemical cycles both from physicalaspects (e.g., shelf-basin exchange, eddy, and upwelling)
and from biogeochemical aspects (e.g., organic matter
supply from river, coastal erosion, and sea bottom
permafrost melting). Readers can refer to details ofbiogeochemical processes in Themes 3 and 9.

resolution has to be less than 1 km. Because of limited
computational resources, we should now verify
convection schemes and focus on individual processes.
From the viewpoint of future prediction, it is meaningful
to explore the possibility of thermally-driven ocean
circulation under global warming.
These physical oceanographic changes are closely
related to biogeochemical cycles and marine ecosystems
in the Arctic Ocean. The extension of river water, sea ice
meltwater, and shelf-origin water pathways accelerates
biogeochemical cycles via enhanced biologicalproductivity. After sea ice melting, air-sea gas exchange is
promoted by vertical mixing, but is restricted by
freshwater input. Gas emissions accompanying sea ice

Decadal strategy in Japanb. Satellite remote sensing
Satellite measurement is very useful for monitoring theArctic sea ice area, where ship-based expedition isdifficult. Among a variety of satellite sensors, all-weather
type microwave sensors enable daily global mapping andhave played a central role in sea ice research for several
decades. The main sensor is AMSR2, developed in Japan.
The AMSR2 has four times higher spatial resolution thanthe U.S. SSM/I and enhanced data utility. The AMSR
series is indispensable for monitoring and research of sea
ice and its continuous operation is an international
responsibility. Considering the period of AMSR2’s
durability, the succeeding sensor should be launched by
2020/21. The development of higher-resolution sensors is
also important for ice-edge monitoring and for analyses offine-scale sea ice variations.
The estimation of sea ice thickness is necessary toevaluate sea ice volume and growth/melting rate. There
are some satellite algorithms for estimating sea ice
thickness from sea ice surface conditions; however, theiraccuracy is still insufficient, especially in the multi-year
ice zone. To obtain data that is independent of sea ice type,direct measurement of sea ice surface height is practical.
NASA and ESA are operating ICESat with a laser sensor
and CyroSat with a radar sensor, respectively. These
altitude sensors provide information on the surface heightof the ocean, in addition to sea ice. The spatial distribution
and strength of ocean circulation calculated from sea
surface height are closely related to ocean heat transport.
Altitude data is therefore important to clarify mechanismsof sea ice variations and to predict corresponding futureclimate. Since the accuracy, resolution, and frequency of
current sensors are unsatisfactory, further sensor
development and operation of multiple small satellites
should be discussed.
Visible/infrared sensors (e.g., MODIS and LANDSAT)
and synthetic aperture radars (e.g., PALSAR andRadarSat) are also valuable. In spite of the state-of-the-art
development, operation, and analysis of satellite products,
these data have not been popularized in the Japanese
Arctic research community. Well-established dataarchiving for easy access is an effective way to extend therange of satellite users. Satellite remote sensing and its
application to Arctic environmental research can be one ofJapan’s leading roles, given the country’s geographicallocation away from the Arctic region. More extensive
utilization of present sensors, development of new sensors,a. International programs and collaboration
IASC recognized that international collaboration isindispensable for Arctic Ocean research, in particular forfield observation. Non-Western countries such as China,
Korea, and South Africa have already established theirown icebreakers for Arctic research. We should devise
strategies to maintain and ensure the Japanese scientificcontribution. The main target regions of Arctic coastal
countries with their own icebreakers are territorial waters
and exclusive economic zones. It is hence important thatJapan leads scientific research from its neutral position asa non-coastal country. Japan’s sophisticated skills insatellite remote sensing and modeling are now being
recognized worldwide. We have active field, satellite, andmodeling researchers. The trinity framework and thecenter of excellence would produce pioneeringachievements.
Major international Arctic Ocean projects are
summarized in Figure 8. The first year-long observationof heat budgets between air, sea ice, and ocean was
SHEBA in the late 1990s. Since there is no other example
of such long-term measurement specializing in heatbudgets, the SHEBA products are frequently cited, evenafter more than 15 years. During the 2000s, CASES,
BGEP, and DBO were conducted in the Pacific Arctic
region, and NPEO, ASOF focused on the Atlantic side.
JAMSTEC, Hokkaido University, TUMSAT, and NIPR
participated in these various projects. As IASC programs,
MOSAiC and AODS are scheduled to take place within
the next decade. Japanese research communities are also
expected to plan and implement field activities. Japan
presently plays a leading role in simultaneous radiosonde
observations referred to as ARCROSE. In satellite remotesensing frameworks, many polar researchers are engaged
in the GCOM-W mission operated by JAXA. The
obtained sea ice data are utilized worldwide so that thecontinuous operation of microwave sensors is aninternational responsibility. Modeling studies themselves
do not always require international cooperation. However,the AOMIP started in the 2000s and has provided valuable
resources to detect common biases and improvement
points for Arctic Ocean models. Recently, a few Japanese
researchers attended the successor FAMOS annual
meetings. As a forum for human interactions, ART iscommitted to interdisciplinary collaboration among
young scientists. We should take advantage of theseinternational frameworks, which produce many
opportunities for new cooperation.
21

Figure 8: Major international projects on Arctic Oceanography. Right arrows mean that the end period
has yet to be determined.

NCEP-CFSR reanalysis products. We should proceedwith data validation. In addition to meteorological radarobservations, SHEBA-like intensive field campaigns arealso ideal for capturing temporal variations in snow depth
and sea ice thickness. During the NSIDC Operation
IceBridge mission connecting the ICESat and ICESat-2
periods, electromagnetic instruments loaded on helicopter
were sometimes used to measure springtime snow depth
and sea ice thickness in the Pacific Arctic region.
In Japan, the JAMSTEC R/V Mirai has worked on
atmosphere and ocean observation in the sea ice reduction
zone for more than 10 years. The radiosonde, in particular,
is a unique item. The automatic release equipment enables
very frequent operation even with a small group. In 2013,
two weeks of fixed-point observations were conducted by
the Mirai cruise for the first time. Pan-Arctic simultaneousradiosonde measurements were achieved in cooperation
with land operational stations in Ny-Alesund, Alert, andEureka. Since the importance of this mission and foresightwere expressed beforehand during the IASC atmosphere
working group meeting, international cooperation from
Germany and Canada could be ensured. The U.S. andRussia are also developing an interest in these activities.
This mission, named ARCROSE, is now being developedin terms of novel studies covering Arctic weather
forecasts and the assessment of Arctic impacts on midlatitudes. The aim of ARCROSE is consistent with PPP. It
is noteworthy that this project started in Japan and isrecognized as a MOSAiC pilot study scheduled for 2018and 2019.

expansion of human resources, and organization ofresearch institutes should be promoted.
c. Field observation
Japanese research communities have adequate
achievements in terms of ship-based observations in the
Pacific Arctic region. Unfortunately, the field campaign
operated by Japan has been confined to outside themarginal ice zone. To ensure a continuous international
contribution, our biggest challenge is to fill data blanks
through year-long observation in Arctic sea ice zones.
From the viewpoint of heat budget analysis, it is importantto propose a new standard, following SHEBA. To advance
Arctic oceanographic research in Japan, additional
facilities for in situ measurements in sea ice zones (e.g.,through icebreakers and unmanned stations) should beinstalled (see icebreaker conception in Chapter 9).
IPS mooring sensors play an active role in time series
observation of sea ice. Data accumulation in the spatial
direction is enabled by AUV and ice-class profiling floats.
If the estimation of sea ice thickness from ADCP becomespractical, a dramatic increase in amounts of data is
expected. In situ measurements at the spatial scale ofindividual ice floes contributes to refinement of sea ice
models. On the other hand, an important task forcontinuous implementation systems is to foster humanresources with know-how through international
cooperation. Having a grasp of cloud and precipitation
systems and snow processes over sea ice is also important
to clarify sea ice variation mechanisms. An ice massbalance buoy is a robust tool for capturing seasonaltransitions in snow depth on sea ice but the number ofbuoys is insufficient to allow for discussion of spatial
patterns. Other snow depth data is available from thed. Numerical modeling
Skills in predicting recent rapid decline and thickness
distribution changes in sea ice in climate model
22the Arctic Ocean, eddy-scale phenomena (which are
generally finer than those in mid-latitude regions) andcomplex sea bottom topography control not only shelfbreak currents but also basin-scale ocean circulation.
Horizontal model resolution should therefore be of anorder of 1 km for accurate simulation of pan-Arctichydrographic fields. Hardware restrictions will probably
be overcome through next-generation high-performancecomputers. In the coming stage, model configuration andexperimental design should be rechecked. Mesoscaleeddies, internal waves, and deep convection are important
processes for inclusive solution of Arctic Ocean
environments. Convective mixing, with its horizontal
scale of 100 m, cannot be explicitly resolved even using
high-end supercomputers. Following achievement ofhigh-resolution experiments, additional approaches would
be necessary for better modeling performance of densewater plumes and mixing processes. The reformation of
convection schemes based on idealized modelexperiments should be factored into the choices.
In atmospheric modeling efforts, regional weather
forecast models such as WRF should be established to
examine meteorological variations reflecting air-iceocean interactions in marginal ice zones. These model
improvements require data accumulation not only fromfield campaigns but also through satellite remote sensing.
Japanese management and analysis of satellite products ishighly valued. In addition to the above-mentioned process
studies, reanalysis data used as atmospheric boundary
conditions for sea ice-ocean models and validation
methods for model performance should also be refined(see also Themes B and C).

experiments under global warming scenarios are not yet
adequate. Model biases are attributed to various factors,
as referred to in Theme B. In this section, we describe
points for model improvement to study Arctic
oceanographic processes.
Most sea ice models have been developed following
Semtner-type thermodynamics and Hibler-type dynamics.
In the thermodynamic part, accurate expression of sea ice
albedo, considering snow depth and melt ponds, is key. It
is preferable to reproduce temporal changes in albedo
differing between multi-year and seasonal ice zones.
Although some models explicitly formulate the melt pond
property itself, the choice of direct calculation of melt
pond or indirect representation as an albedo change (i.e.,
parameterization) would depend on availability ofvalidation data and computational costs. In the dynamics
part, present schemes do not sufficiently include local
mechanics with ice floe scales lower than 10 km. Sea ice
rheology on internal stress was originally developed for
medium-resolution models with their horizontal grid sizeof dozens of kilometers. The applicability of similar
formulations to higher-resolution (grid of several
kilometers) models should be verified. Further sea ice
reduction in the Arctic Ocean is considered to enhancewave-ice interaction, where wind-driven ocean wave
breaks pack ice into small floes. The variable coefficientsof air-ice and ice-ocean drag (e.g., depending on sea ice
thickness and melt pond conditions) would improve
momentum transfer between air, sea ice, and ocean.
The ocean model component should also be improved.
For example, medium-resolution models barely reproduce
the intrusion of dense shelf water into basin interiors. In

Summary
could therefore produce international contributions
through a combination of short-term spot sampling in
winter and year-long mooring (i.e., focusing on warm
water intrusion under sea ice).
Numerical modeling is a useful tool for pan-Arctic
mapping of oceanographic structures, but still has various
weaknesses, such as model bias and high computationalcost. We should now try to quantify ocean heat impact on
sea ice, intrusion of dense shelf water into basin interiors,and cloud/cyclone formation. The global thermohaline
circulation originating from the bipolar regions involves
multiple phenomena scales (e.g., turbulent mixing, deep
convection, eddy transport, and basin-scale oceanic
currents). The interaction between individual multi-scale
processes should also be addressed using high-resolution
Arctic Ocean models for a unified understanding.
There have been many process studies, focusing on
individual contributions of atmosphere and ocean to
Arctic sea ice variation. The interaction between the threesystems is also an important theme for clarification. For
example, it has been suggested that the frequency of eddy
generation and corresponding ocean heat transport depend
on surface wind patterns in the western Arctic. On theother hand, ocean heat may alter atmospheric circulation
fields via sea ice retreat. Such feedback processes will
become important issues to be examined in future studies.
For seasonal forecast of sea ice distribution, assumptionsof characteristic wind patterns or of ensemble ice-ocean
experiments using varied wind-forcing data aresometimes necessary. Quantifying how sea ice and oceanchanges affect atmospheric condition would increase the

The Japanese research community has had numerous
achievements through field investigations in the PacificArctic region, where sea ice declined rapidly in the 2000s
and where most sea ice disappears in summer. The R/V
Mirai Arctic cruise led both atmospheric and ocean
observation in the Chukchi continental shelf and theCanada Basin area for about 15 years. In particular, there
has been the deployment of mooring buoys to estimate
horizontal heat transport of Pacific-origin water, as well as
turbulence measurements to address vertical ocean heattransfer. In addition, processes in the atmosphericboundary layer, such as ocean surface cooling, cyclone
generation, and changes in cloud bottom altitude, havebeen clarified. In recent years, the T/S Oshoro-maru of
Hokkaido University sometimes entered the northern
Bering Sea and the Chukchi shelf to obtain high-latitude
oceanographic data. We thus have an international
reputation for ship-based observation in the Pacific Arctic
region.
The Pacific Arctic region is a good example of aseasonal ice zone. We therefore plan for this region to bea priority area of comprehensive study. Whereas the
Canadian, Chinese, and Korean icebreakers regularlytransect the central Arctic basins, the U.S. has started tofocus on marginal ice zones in the Beaufort Sea.
Additionally, ICESCAPE is a breakthrough project,through which massive under-ice blooms ofphytoplankton were discovered. These campaigns also
provide a reference point for our future activities. Even
though we could own an original icebreaker, wintertime
cruises are severely restricted by weather conditions. We
23

accuracy of seasonal forecasts. Development of regional
Arctic climate models is another approach to address theabove-mentioned analyses (see also Theme B). This effort
has already started in the Naval Postgraduate School, U.S.,
and further improvements to reproduce various
phenomena scales are expected. We now have advanced
model development techniques, powerful supercomputing
systems, and individual model components foratmosphere, ocean, land, and ice sheets. The time to
discuss better coupling methods is now approaching.
Close collaboration in field and modeling studies isstrategically important to advance polar research. Benefits
would result, not only from direct comparison of results,
but also through approaches using data assimilation. In thetropical and mid-latitude ocean, data assimilation is
widely recognized as a general research tool, taking fulladvantage of Argo buoy data. Unfortunately, the target
variables assimilated in the Arctic Ocean are confined tosatellite-based sea ice concentrations and mooring-based
ocean velocity over a part of the continental shelf, because
both available data amounts under sea ice cover and model
performance are still insufficient.
However, over the next decades, we should look ahead
to an innovative style of Arctic research with data
assimilation, because we expect to have an enhanced
observational network using automatic equipment andimproved model performance. The data assimilation
system itself has a common specification across the world
ocean. In the polar ocean, a strategy for obtaining underice in situ data is important. For example, if we develop
next-generation profilers that automatically move under
sea ice in winter and lift up to the ocean surface in summer,
the assimilated product would be practical research
infrastructure for a variety of space-time scales as well asa high-accuracy one in the mid-latitude ocean. In addition,
data assimilation is regarded as a useful tool to estimate
optimal values of model parameters and to construct more
realistic initial conditions for forecast experiments. It is
desirable to develop short-term prediction systems,
similar to JCOPE and JADE, and to inform commercial
vessels sailing the Arctic Sea Route of weather, sea ice,and ocean conditions. These efforts would further
contribute to social and economic communities. A
detailed discussion of data assimilation is provided in
Theme C.

24

Theme 3: Biogeochemical cycle and ecosystem changes
Abstract

study sites that allow centennial-scale continuous dataacquisition of vegetation change such as species
composition and structure change is important. Also,
satellite observations that record signals of vegetation
change, development of vegetation dynamics models that
perform reliable predictions on long-term ecosystemchanges, and understanding the geographical distribution
and its accumulation and decomposition mechanisms ofsoil organic carbon (SOC) are crucial for the scientificprogress. For the geochemical transport from land toocean, we need to develop an extensive observation
network around rivers and coastal areas in the Arctic tomonitor fluxes of pollutants, carbon, nutrients, and trace
metals etc. that are released by coastal/soil erosion andthawing of ice sheet and permafrost. For marine
ecosystems, obtaining the observation data with no spatialand seasonal gap is important. For example, it is necessary
to obtain the data by ice camps and year-roundobservation by sediment trap and mooring system tounderstand the seasonal variation of biogeochemistry andecosystems. Furthermore, by comparing and integratingthese data with the numerical models andincubating/feeding experiments, it is possible to evaluate
quantitatively the relationship between biogeochemical
cycle and ecosystem along with the effects of ocean
acidification.

Biogeochemical cycle across the atmosphere, land, andocean is closely related to greenhouse gas dynamics suchas CO2 and methane, aerosols that affect cloud formationand solar radiation, and nutrients that sustain marine
ecosystems. In the Arctic regions, sea ice, ice sheets, snow
cover, and permafrost play a major role inbiogeochemistry and complicate the processes further.
Here, we highlight the following four questions that
describe important aspects of changing biogeochemistry,
which is the other side of the same coin with theperspective of environmental changes.
Q1: How are concentrations of greenhouse gases andaerosols in the atmosphere changing?
Q2: How are biogeochemical cycles that relate toterrestrial ecosystems changing?
Q3: What is needed for quantitative elucidation of thegeochemical material transport from land to sea?
Q4: How are biogeochemical cycles that relate tomarine ecosystems changing?
As for the atmosphere, since observational data are
currently very poor in Siberia, deployment of new
observation sites to implement year-round observations ofatmospheric trace gases is important in Siberia. The use ofsatellite data and aerosol observation over the ocean using
marine vessels on a regular basis are also necessary. For
terrestrial ecosystems, the implementation of long-term

Introduction
It is almost certain that the increase of CO2 in theatmosphere is the main cause of the global warming
experienced in recent years, and this problem has attracted
worldwide interest. While CO2 has continued to bereleased into the atmosphere by human activities, it is alsoa fact that the concentration of CO2 in the atmosphere has
been moderated in some part by land and ocean absorption.
In reference to the AR5 of IPCC (IPCC 2013a), about 40%of the CO2 released into the atmosphere by burning offossil fuels etc. has been absorbed by the land, and another
20% by the oceans, each year. From this, it is clear that, inorder to understand the dynamics of CO2 in theatmosphere, it is necessary to study the carbon cycle in theatmosphere, on land, and in the ocean. Figure 9 is aschematic diagram of the biogeochemical cycle in the
Arctic region. In this region, a unique feature notextensively seen in other regions plays a significant role:snow, land ice, and sea ice. In addition, climate change isanticipated to be particularly strong in subarctic andArctic terrestrial areas (Figure10; IPCC 2013b). Grasping
accurately the impact of climate change on subarctic andArctic terrestrial ecosystems (hereinafter, referred to as
Arctic terrestrial ecosystems: ATEs) is crucial forunderstanding the feedback affecting climate throughbiogeochemistry.
In the Arctic regions, the primary production (i.e.,
photosynthesis) of boreal forests and marine
phytoplankton is one of the major factors governing CO2
concentration in the atmosphere, and it also has a largerole in the global carbon cycle. Understanding carbon

dynamics quantitatively, and its impact on ecosystems in
the Arctic region, is very important for predicting thefuture global climate. The Arctic is unusually significant
in this, because the warming there is particularly
remarkable.
CO2 is not the only factor related to the climate change.
Methane emissions that may be increased by thawing of
permafrost due to global warming, and the release of
methane from the subsea permafrost of the Arctic Ocean
could also have a significant impact on the climate.
Furthermore, aerosols such as black carbon 14 (BC,Figure 9: Schematics of the biogeochemical cyclein the Arctic.

14Black carbon (BC): Black carbon (BC) is the strongly light-absorbing component of fine particulate matter present in the atmosphere, containing
graphite-like micro-crystalline structures.

25

Figure 10: Prediction of global warming summarized by IPCC(scenario RCP8.5). It expresses how manydegrees Celsius the average temperature of 2081 to 2100 is expected to rises from the averagetemperature of 1986 to 2005. Warming in the vicinity of the North Pole has been particularly intense. The
cause is regarded as albedo feedback caused by reduction in the extent of snow and sea ice withwarming. (IPCC, 2013b, Figure SPM.8. Maps of CMIP5 multi-model mean results for the scenarios
RCP2.6 and RCP8.5 in 2081–2100; (a) annual mean surface temperature change)

atmosphere-ocean system is a strong determinant for the
climate and the environment, it will be important in thelong-term to clarify the dynamics of climate change andecosystem roles. This could be achieved using modelingstudies, in addition to field studies and satellite
observation.

emitted by frequent burning of biomass in the subarcticzone) produces cloud condensation nuclei that change theradiation process of the atmosphere and of snow surfaces,
thereby changing the climate. Substances of terrestrial
origin that enter the ocean from rivers and coasts, andsubstances transported by air that fall on the sea surface,
are major factors in the function of marine ecosystems.
Since the behavior of individual parts of the land-

Q1: How are the concentrations of greenhouse gases and aerosols in the atmospherechanging?
a. The importance of this topic and current conditions
Trace components in the atmosphere (greenhouse gases,
short-lived gases 15 , and aerosols) have a significant
influence on climate change through atmospheric budgets,as indicated in the schematic diagram of Figure 11. The
Arctic region is composed of the sea-ice area, which
accounts for most of the Arctic Ocean, the marine area,
which has a large amount of biological production, and theland area, where very large permafrost areas and forest
regions occur. These three areas play roles of both sourceand sink for atmospheric trace components. To clarify thecirculation process and trends of atmospheric tracecomponents, a number of countries, including Japan, havecontinued long-term observations, for instance, in NyÅlesund (Svalbard Islands), Barrow (Alaska), and Alert(Canada). In recent years in the Arctic, changes that areconsidered as effects of climate change, for example, asudden reduction in the area of summer sea ice, have been

observed. It is certain that such sudden environmental
changes have a significant impact on the distribution andconcentration of atmospheric trace components. To
understand changes in the distribution of thesecomponents, and the influence of environmental changes,
progress in observational studies is needed. This isessential if we are to prepare responses to environmental
changes that may occur, and to accumulate knowledge ofchanges in biogeochemical processes in the atmosphere.
Expansion of the regions in which seasonal sea-ice andopen water occur, relative to past conditions, is believedto enhance CO2, exchange processes, to release shortlived (less than one day to several weeks) gases such as
aerosol precursors16 (e.g., DMS: dimethyl sulfide) to theatmosphere, and to increase the number of airborne
particles of sea-salt. Knowing the distribution of CO2
exchange in the ocean, and its seasonal change, is very
important in understanding atmospheric carbon cycling.

15
Short-lived gas: Is a gas with high reactivity and short chemical life, less than one day to several weeks, in the atmosphere (e.g., O3, NOy, SO2,
volatile organic matter).
16
Aerosol precursor: It exists as gas in the atmosphere and can become an aerosol particle after conversion into a low vapor-pressure ingredientthrough an oxidation reaction in vapor phase, and condensation onto an existing particle, and can be converted into an aerosol-particle ingredient after
condensation onto an existing particle and chemical reaction there.

26

Figure 11: Schematic of biogeochemical cycling with focus on the atmosphere

wet areas, in emission of short-lived gases (volatileorganic compounds: VOC) from forests, and in wildfire
patterns. Thus far, observations of greenhouse gases andassociated gaseous compounds in the Arctic region,
suggest that inter-annual and seasonal changes are related
to emissions from fossil fuel consumption, deforestation,
biomass burning, and wetlands (Morimoto et al., 2010).
Biomass burning, in particular, does not only causes
release of greenhouse gases but is also an important sourceof light-absorbing aerosols (e.g., BC and BrC - browncarbon20). These greatly affect the albedo of snow and ice
surfaces when deposited on them. Furthermore, we should
include impacts from the expansion of human activities
expected during extended periods of Arctic warming (e.g.,use of Arctic shipping routes and exploitation of resourcesin the region). This could be addressed by future studies
on the concentrations of atmospheric trace components(e.g., CO, CO2, NOx, and BC), their spatial distributions,and their impact on climate change. The contribution of
long-range transport of anthropogenic substances fromoutside the Arctic Circle has also been pointed out, basedon long-term observations of greenhouse gases andaerosols (Quinn et al., 2007; Morimoto et al., 2010). Basicscientific knowledge of the circulation of tracecomponents in the Arctic atmosphere, and their influence,has been obtained from past energetic studies, but there
remains significant uncertainty and many unexplained

In addition, expansion of open water is a factor inincreasing aerosol concentrations because the release ofaerosol precursors and sea-salt particles is promoted by
the greater water surface accessible to the wind. The
increase in the aerosol concentration increases the numberof cloud condensation nuclei17 and can influence radiative
forcing indirectly by its effects on cloud processes 18(Lubin and Vogelmann, 2010). Increased sea-salt particles
in the atmosphere promote effective removal of acidic
gases of artificial origin (such as SOx and NOy) byheterogeneous reactions on aerosol particles anddeposition processes.
This is closely related to the atmospheric cycling ofsome short-lived gases. In addition, frost flowers 19 thatform on seasonal sea ice (winter-spring) become a sourceof sea-salt particles. There is a possibility that sea-salt
particle emission from seasonal sea ice changes theaerosol distribution in the Arctic from winter to spring.
The heterogeneous reactions on frost flowers, and therelease of highly reactive halogen species into theatmosphere by sea-salt particles, are closely related toatmospheric chemical processes (e.g., oxidation of shortlived gases, O3 depletion, Hg removal) that occur in thepresence of solar radiation (particularly during polar
sunrise).
In terrestrial areas, changes in soil and vegetation could
cause changes in emission of the greenhouse gases from17

Cloud condensation nuclei (CCN): Particles that provide targets for condensation of atmospheric water vapor, for formation of cloud particles.
Aerosol and cloud formation and their influence on climate: Vapor condenses on aerosol particles in the atmosphere and they become cloudparticles, and a cloud is formed. The increase (decrease) in density of aerosols brings increase (decrease) in cloud particle density and decrease(increase) in cloud particle diameter. This greatly changes the lifetime and optical characteristics of a cloud. These conditions are closely related toemissions, and may greatly affect climate change
19
Frost flower: At low temperature, ice crystals form on the surface of sea ice as it freezes. The salinity of frost flowers is very high since brine(concentrated seawater) on the sea ice coats them. By the chemical reactions that occur on the frost flowers, and due to fragmentation caused bystrong winds, highly reactive components and sea-salt particles are released into the atmosphere.
20
Brown carbon (BrC): This is a particulate organic compound with light absorption characteristics. It is released to the atmosphere by combustion.
18

27

Figure 12: Conceptual picture of platforms from which to observe the biogeochemical cycle with focus on
the atmospherein the Arctic Ocean has often been carried out on open
water during the summer, observations in sea-ice areas, inwinter using icebreakers, and year-round at unmanned
weather and aerosol observation bases on the sea ice arealso necessary. Furthermore, in order to understand the
distributions of atmospheric trace components (inparticular, short-lived gases and aerosols), it is importantto regularly conduct intensive observation that makes fulluse of aircraft, and other flying objects, to capture their
vertical distribution from the ground to the upper
troposphere, and their horizontal distribution over areas ofland, open water, and sea ice. Moreover, because there aremany constraints on spatial observation by research
vessels and airplanes, an overall grasp of the spatial
structure of greenhouse gases, short-lived gases, aerosols,and clouds by satellite observations should also be
performed. From these observations, (1) the
spatiotemporal distribution of atmospheric tracecomponents, (2) distributions of the emission, absorption,and deposition amounts, (3) their seasonal changes, and(4) the inter-annual changes of gases and aerosols from thesea and land surfaces may be clarified with high resolution
and high accuracy. Based on the results obtained bymaking full use of atmospheric composition and transportmodels, we should be able to elucidate the mechanisms ofinteraction among the oceanic, terrestrial, andatmospheric cycles of atmospheric trace components(greenhouse gases, short-lived gases, and aerosols) in the
Arctic. As a result, we should aim to predict climatechange with greater accuracy.

points about interactions of atmospheric trace components,
and the overall mechanism.
b. Future studies
In order to understand the dynamics of greenhousegases, short-lived gases, aerosols, and their influence on
climate change in the Arctic atmosphere, long-term andprecise observation of spatiotemporal patterns isimportant. See Figure 12 for an outline of mainly
atmospheric observations about biogeochemistry. Since
the target regions cover a wide area, within which are seaice, open ocean, land, and atmosphere, it is important thatthe research community of Japan become the center fromwhich we expand the observation of atmospheric tracecomponents, aerosols, their isotopic ratios, and clouds,
using ground-based observations, ships, aircraft, otherflying objects, and satellites suitable for the subjects andregions to be observed.
For ground-based observations, in order to have newdata be comparable with past data, current observations
should be continued in cooperation with research
institutes both domestic and abroad. In Siberia, whereobserved data are significantly poor, the observatories
should be new, and year-round observation of atmospheric
trace components should be implemented. In oceanic
areas, because understanding the distribution of
atmospheric trace components in open water and sea-ice
areas is essential, observations of aerosols and short-lived
gases should be executed regularly utilizing research
vessels and icebreakers. Since the use of research vessels

28

Q2: How are biogeochemical cycles relate to terrestrial ecosystems changing?
a. Importance of this topic and current conditions
Changes in temperature and precipitation have strong
impacts on ATEs. For vegetation, changes inphotosynthesis, respiration, biomass, and vegetation typeoccur. In addition, the fertilization effect 21 fromincreasing CO2 concentration in the atmosphere has large
impacts on ecosystems, and it is believed that the global
average of photosynthesis will increase by 10–30% froma 2-fold increase in the CO2 concentration by the latter halfof the 20th century. In conjunction with this, it is estimatedthat land, acting as a carbon sink, might absorb
approximately 40% of annual carbon released to theatmosphere artificially by combustion of fossil fuels etc.
(IPCC, 2013a). For these reasons, it is important toestimate as accurately as possible the contribution of the
Arctic ecosystem to these carbon budgets. Since ATEs arelikely to be significant sources of CO2 and methane,
precise understanding of these dynamics is an urgent issue.
The interaction of climate and ATEs is not always in
only one direction (i.e., climate to ATE). There is also
influence from ATEs to climate, and this is the basis of acomplex interaction22 (Figure 13). Therefore, in order tounderstand the variation of terrestrial ecosystems andbiogeochemistry, the impact on climate exerted by ATEs
through biogeochemical cycling and physical processes atthe land surface, must be considered. However, current
understanding of Arctic terrestrial ecosystems is
incomplete. By promoting scientific understanding fromthe perspective of system science, quantitative

understanding of feedback with high uncertainty, such as
impacts on vegetation dynamics due to global warming,and impacts on climate via albedo and carbon dynamics
due to vegetation changes, should be studied further. Mostof the carbon stored in ATEs is present near the groundsurface in the form of SOC. For this reason, dramaticchanges in SOC due to variation in soil temperature andmoisture caused by global warming is expected. Becauseof reports that the amount of carbon stored in peat lands
may be reduced by up to 80% due to a relatively mild
temperature rise of 4 ºC by the end of the century (Ise etal., 2008), exact understanding of SOC dynamics is an
important issue. In particular, considering permafrost
melting, there is a possibility that dramatic changes may
occur. Of particular concern is the possibility that current
zones of permafrost will become wetlands due to global
warming, and that the melted areas will become major
sources of methane. Moreover, since the burning of
biomass emits a large quantity of CO2 in a short time, it isestimated that its influence on climate is significant.
However, because it also causes related changes in
evapotranspiration, surface albedo, and vegetation, as
well as generating aerosols that become cloud
condensation nuclei, quantitative prediction of its effects
is unsatisfactory at present.
Field observation is important to understand thebiogeochemical cycling of ATEs, but field data are limited
because access is difficult in large parts of this area. Thus,
it will be necessary to carry out local observations

Figure 13: Terrestrial ecosystem and climate influence each other with strong interaction.
The development, validation, and application of a simulation model that is able to bundle
elements and processes and connect them in complicated ways, is urgently needed toproject how these actions change in a scenario of climate change.

21
Fertilization effect: The phenomenon that the photosynthetic efficiency of plants (which use CO2 as a carbon source) rises as the concentration of
atmospheric CO2 rises. Because absorption of atmospheric CO2 is increased by the fertilization effect, it has a function as a negative feedback tosuppress a climate change. However, quantitative evaluation of the fertilization effect has not advanced much, and its range (5–30% of the artificial
CO2 discharge) is so wide that uncertainty is great. The results of future studies are much needed and awaited.
22
Various feedback mechanisms to hide behind in terrestrial carbon cycling: CO2 and methane are greenhouse-effect gases causing climate change,
and both include carbon. They circulate through terrestrial ecosystems and the atmosphere via the physiological functions of organisms. The
physiological activity of living organisms reflects the shifting environmental conditions caused by climate change, and in this way, change in carbon
cycling causes feedback to climate change. This feedback is various: some acts as positive feedback to accelerate warming, and others as negative
feedback to suppress warming. Regarding positive feedback, increased microbial activity due to rising soil temperature promotes more rapid
decomposition of soil organic carbon, and can lead to greater rates of release of additional CO2 into the atmosphere. Regarding negative feedback,climate warming increases the amount of photosynthesis and plant biomass, thus increasing the amount of atmospheric CO2 fixed in the plants andsoil of the land surface. In order to make accurate projections into the future, it is necessary to be clear about each of these conflicting feedback
elements, and to model them.

29

dynamics of methane generation.
By
constructing
a
model
that
integrates
biogeochemistry and soil physics, it would become
possible to explicitly predict changes in the depth of thepermafrost (more specifically, the thickness of the active
layer) due to climate change, and to show how the
microbial activity of each layer of soil, affects the
dynamics of methane and CO2. In addition, we could thencontribute to the elucidation of water cycling and the flowof elements that accompany it from land to ocean.
Quantitative understanding of the biogeochemical
processes of terrestrial ecosystems, and projections into
the future, might be accomplished with the construction ofa unified model for land areas (see Q3 for the details).
Remote sensing by satellite, as well as simulation, will
be a powerful tool for understanding ATEs and making
predictions. Recently, there has been progress in theestimation of plant biomass and photosynthesis due toadvances in remote sensing technology (Suzuki et al.,2013). In this way, studies to grasp carbon cycling overwide areas, based on field observation should be
developed. Remote sensing can also be utilized forobservation of large and critical events, such as biomassburning.
It may be said that the application of data assimilation
technology is a key to the next ten years for connecting
field observations to predictive models. We need todevelop objective and integrative statistical technology
able to utilize the accumulated field and remote sensing
data, and to improve simulation models. In particular, by
the application of the 4-D data assimilation technique,using such as the ensemble Kalman filter, there is great
potential to revolutionize the objective model
improvement by field observation and remote sensing
observation. These data assimilation techniques are
already used in atmospheric and ocean science, but theirapplication to terrestrial ecosystem research hardly exists.
Thus, it is also important to train proficient researchers instatistics theory and computer science.
Gathering Japanese study communities, and focusing
on collaboration with international projects and networks,
is indispensable for achieving these future aims. For
example, consider ILTER23 (long-term observation plan)and FLUXNET or GEO GFOI24 (observation of the CO2
exchange between the earth surface and the atmosphere).
It is necessary to unify researchers, and promote the useof the data which study groups have individually acquired
and managed in a traditional manner, and to fix the system
by developing an All Japan Model. The change inbiogeochemistry being reported for ATEs is of greatinterest for the IPCC reports and we should positively
carry out the model inter-comparison with a group ofoverseas research institutions (such as NASA, GISS, andthe Hadley Centre) to perform Earth-system modeling.

continuously to acquire valuable data for the future, andalso to utilize better techniques, such as remote sensing,for spatial observation and capture ecosystem changes
over this wide area. The development of simulation
models able to reproduce current ecological conditions
and processes is indispensable. These are essential tounderstand interactions between environmental changes(e.g., climate change), and the biogeochemistry ofterrestrial ecosystems, and to contribute rational
predictions of future climate. However, development of an
integrated model advances only slowly because there aremany elements that should be included, and the feedback
between them is extremely complicated.
b. Future studies
The research topics needed for ATEs are too numerous
to mention. For this reason, here we list a few that
contribute directly to understanding biogeochemistry at
global scale, and which should be clarified from a longterm perspective.
From the fact that plant biomass functions as a carbon
pool in global carbon cycling, it follows that we must
understand its variation and dynamics. We should set up
long-term plots of land to acquire continuous data on a
century scale, about plant species and community
structure. Included should be clarification of signals ofchanges in vegetation that are observable by satellite.
Furthermore, it will be necessary to perform a reliableprediction about long-term changes in vegetation using avegetation dynamics model. This will lead to quantitative
understanding of the role of terrestrial ecosystems in the
global carbon cycle. As a specific method of fieldobservation, proactive use of non-contact observation
technology (e.g., leaf area index measurement using
fisheye lenses, basal area measurement using the prism
method) in order to efficiently and strategically cover thevast Arctic terrestrial area, is also important.
Specifically, SOC functions as the largest carbon poolin ATEs, and the importance of grasping its distribution,and understanding the mechanisms by which it isaccumulated and decomposed, is noteworthy. Since thethickness of organic soil, in which SOC is mainly
accumulated, changes due to the increase and decrease of
SOC, the physical condition of the soil changes as well.
This means that carbon cycling, as well as energy andmoisture dynamics, must be modeled at the same time.
Therefore, we should promote the fusion of models ofbiogeochemistry and physical qualities of soils from a
medium- to long-term perspective. Integration of
ecological studies and land surface physics research isimportant, but it has not seen much cooperation currently
due to differences in these academic disciplines. Moreover,physical understanding of the soil, based on observationand prediction by models is important for grasping the

Q3: What is needed to quantify material transport from land to sea?
a. Importance of this topic and current conditions
Terrestrial materials are supplied to the ocean mainly
by river or coastal erosion. Arctic rivers transport a large
amount of freshwater and carbon, equivalent to 10% of the
global river flux, into the Arctic Ocean. Therefore, theArctic Ocean is the key for understanding material
2324transport from land to the global ocean. Since deepeningof active layers, melting of ice sheets, increase in riverflow, and acceleration of coastal erosion, all increase with
global warming, the input of terrestrial materials to the
Arctic Ocean is expected to increase. Furthermore, it isexpected that the spatiotemporal extent of the impact of

ILTER: International Long Term Ecological Research
GEO GFOI: Group on Earth Observation - Global Forest Observations Initiative30

Data concerning the flux of carbon, nutrients, and othermaterials of the rivers of North America, and the mainrivers of Siberia, as well as data about their seasonal/interannual changes, are provided by USGS and the ArcticGRO project (e.g., Holms et al., 2012). However, thequantitative understanding of coastal erosion, soil erosion,
ice sheet melting, and materials derived from medium andsmall rivers and groundwater in Siberia, is very
incomplete. With global warming, it is certain that inputsof particles and organic matter to the ocean will increase
due to coastal erosion and ice-sheet melting. For rivers,
the contribution of groundwater will increase with
thawing of the permafrost, and concentrations of majorions, phosphate, and silicic acid would be expected toincrease. On the other hand, it is unknown whether theflux of dissolved inorganic nitrogen and organic matter
will increase or decrease as a whole, because of large
spatial variability (Frey and McClelland, 2009). Thechanges in the quality and quantity of terrestrial materials
that might be caused by changes in vegetation, and byhuman activities such as agriculture, are also unknown. In
addition, inflows of heavy metals and other pollutants tothe ocean from the land are likely to increase.
The distribution of river water in the Arctic Ocean has
been studied using chemical tracers or satellite
observation of colored dissolved organic carbon.
However, for most terrestrial materials, processes such as
removal and redistribution in river mouths and coastal
regions are not well quantified. Therefore, their fate in theocean, and impacts to ocean ecosystem andbiogeochemical cycles, are not well known.

terrestrial materials will expand when the area of theseasonal ice zone increases. The release of organic carbon
stored in permafrost attracts attention in particular, but its
feedback to the climate largely depends on whether the
carbon settles in coastal sediment or is re-mineralized andreleased to the atmosphere as greenhouse gases (i.e., CO2
and methane). In addition, ocean acidification caused byincreased absorption of anthropogenic CO2 is particularly
serious in the Arctic Ocean. Since the addition ofterrestrial carbon is expected to promote ocean
acidification, this may have a serious impact on Arctic
Ocean ecosystems (Theme 9).
Generally, inputs of nutrients, trace metals, anddissolved organic matter from land are factors that candirectly affect the productivity of marine ecosystems. In
addition, dissolved and/or suspended terrestrial materials
can limit primary production by decreasing light
penetration of the water column. However, thecontribution of terrestrial materials to the biologicalproductivity of the Arctic Ocean has been consideredsmall. In recent years, new observations revealed seasonaland spatial variations in concentrations of terrestrial
materials in the major Arctic rivers. The quantity andquality (e.g., inorganic / organic, biodegradable /recalcitrant) of these materials are expected to changewith global warming. The fate of terrestrial materials
should also be affected by environment changes in coastal
areas, such as decreased summer sea-ice cover andincreased water temperature. Therefore, the importance ofterrestrial materials in Arctic marine ecosystems is now
getting more attention.

Figure 14: Schematic diagram of observations about transportation of matters of terrestrial origin fromland to sea

31understanding or prediction of the influence of terrestrial
materials on the ocean, their quantitative understanding is
still poor. Therefore, it is recommended that some coastal
regions be chosen for focused monitoring of changes inbiogeochemical cycling of terrestrial materials. In order tounderstand seasonal and inter-annual variations in the
distribution of terrestrial materials, photochemical
processes, biological uptake, and the effects of physicalenvironment on these, it is necessary to carry out
comprehensive observations using small vessels andmooring systems, or seafloor observation platforms withsensors and automated water samplers.
For mooring observation in shallow waters, there canbe problems of biofouling and damage by sea ice.
Overcoming these challenges will enable detailed andquantitative understanding of the influence of terrestrial
materials on biological production, ocean acidification,and the removal and mineralization of terrestrial carbon.
Terrestrial materials may eventually flow out from the
Arctic Ocean into the North Atlantic Ocean and thereby
affect biogeochemistry and biological production more
extensively. Therefore, there is need for large-scale,spatial coverage in observations of oceans and seasadjacent to the Arctic Ocean. In addition to shipboard
observation, remote sensing of colored organic matter
distribution, under-ice observations from moorings, anduse of autonomous underwater gliders equipped withsensors and water samplers, will enable 3-D mapping ofterrestrial materials in the ocean. The use of newly
developed tracers for terrestrial matter is expected to
expand our knowledge about their fate in the ocean.
Furthermore, it is also very important to develop andimprove
numerical
modelsforland-ocean
biogeochemistry based on these observations andexperiments, in order to predict future changes in the fluxof terrestrial materials and their impacts on marine
ecosystems in the Arctic and other global oceans.

b. Future studies
In order to monitor changes in the flux of terrestrial
materials such as nutrients, carbon, and trace metals, andtheir influences on ocean ecosystems, it is necessary to set
up and maintain an integrated observation network thatcovers river, estuary, and coastal areas (Figure 14). Since
the inflow of these materials and the cycling processes in
the ocean are being changed by global warming, it isdesirable to start long-term (more than 10 years)
monitoring immediately. For this, international
collaboration is essential and Japan has a history ofcollaborative observations on land in Siberia and North
America, as well in the Arctic Ocean. Integration anddevelopment of these observations with new stations andequipment, within an observation network, will fill thescience gap and develop studies in the frontier that links
the land to the ocean.
On land, it is important to monitor material
concentrations and their seasonal and long-term
variability in rivers, including small ones, using sensors or
periodical water sampling. Combining these data withhydrological observations on land (Theme 4), will enable
quantitative understanding of processes that determinematerial flux from land to the ocean. In addition,
incubation experiments on soil and water are necessary forthe interpretation of observations, and for development ofpredictive models to project future changes in material
flux, with changes in temperature or soil moisture.
Furthermore, detailed chemical analysis of soil and water
samples may provide new tracers of terrestrial materials
useful for understanding their distribution in the ocean.
For materials coming from coastal erosion and ice-sheet
melting, it is necessary to grasp the distribution, scale, andfrequency of the supply to the ocean, using observations
from land and vessel.
Although modification, removal, and redistribution
processes in estuaries and other coastal areas are keys for

Q4: How are biogeochemical cycles that relate to marine ecosystems changing?
a. Importance of this topic and current conditions
Recently, due to warming and the rapid decrease of sea
ice in the Arctic Ocean, the quantitative evaluation of how
biogeochemistry and ecosystems change, and how muchinfluence greenhouse gases such as CO2 and methane
have on the exchange between atmosphere and ocean,
have become important issues for understanding theclimate system, not only of the Arctic, but also globally.
In Figure 15, we show a schematic of changes in thebiogeochemical cycles and ecosystems of the Arctic
Ocean in a scenario of global warming and decrease of sea
ice. It is estimated that currently, the Arctic Ocean absorbs
66–199 × 1012 gC from CO2 each year, the equivalent of
5–14% of the global CO2 budget (Bates and Mathis, 2009).
From this, it can be said that the Arctic Ocean has asignificant influence on global carbon cycling. However,since this estimate is based on data that are biased tosummer conditions and cover a limited area of the sea,
providing reliable estimates requires that we clarify
variation by season, and by differences in regions(marginal seas and central basins), of CO2 exchange
between atmosphere and ocean. In addition, it is importantto understand comprehensively the physical, chemical,
25

and biological processes that affect absorption and releaseof CO2. These include such as increasing sea surface
temperature, freshening (dilution) of seawater, and ocean
acidification, as well as changing primary productivity(CO2 uptake) and phytoplankton assembladges. Also, see
Section 2 regarding exchange of other greenhouse gases
and aerosols between atmosphere and ocean, and theirimpacts on climate change. Note that the methane released
from the Siberian shelf seas alone (8×1012 gC a year;
Shakhova et al., 2010) was equal to that of all other world
oceans combined, and this amount would be expected toincrease with the ongoing thawing of subsea permafrost.
Primary production that affects atmosphere-ocean CO2
exchange is an important factor in the function of marine
ecosystems. Due to recent decreases in sea ice coverage in
the Arctic Ocean, insolation into the water column
increased, and this may increase primary productivity.
However, melting of sea ice enhances ocean stratificationand the growing surface layer of freshwater deepens thenutricline25, resulting in decreased nutrient supply fromdeeper water. This could actually reduce primary
productivity. In regions where upward movement of
nutrients are inhibited, eddies may play an important role

Nutricline: The layer in which the nutrient concentration sharply increases with depth in the water column.

32

Figure 15: Biogeochemical cycles and ecosystem changes in the Arctic Ocean with warming anddecease in sea ice. The figure at the top right corner was compiled based on F. Fetterer and C. Fowler.
2006, updated 2009. National Ice Center Arctic Sea Ice Charts and Climatologies in Gridded Format(http://dx.doi.org/10.7265/N5X34VDB).

organic matter is supplied. In addition, many questions
remain unanswered regarding the influence of increasingwater temperature on the dynamics of bacteria and othermicrobes in the Arctic Ocean.
For marine ecosystems, another important issue isocean acidification. In the Arctic Ocean, when the sea-ice
cover that previously prevented absorption of CO2
decreased, acidification proceeded rapidly (YamamotoKawai et al., 2009). As acidification has progressed, somemarine areas are already able to dissolve calcium
carbonate, and the areas in which this condition exists will
inevitably expand in the future. There is concern thatplankton and benthic organisms that have shells of
calcium carbonate may be damaged, and that higher
trophic levels may be affected via food chains. In anothercase, on the bottom of the shelf under the Chukchi andEast Siberian Seas, the seawater is acidified by CO2
produced from the decomposition of organic matter.
Because the supply of terrestrial organic matter is
expected to increase, acidification of the bottom layer
could increase even more, and would be expected toinfluence benthic organisms.
Bottoms of continental shelves, such as in the Chukchi
and East Siberian seas, are important sites for study of thecycling of nitrogen and trace elements. Denitrification29
occurs at the bottom of the shelf, and nitrogen is lessabundant in water of Pacific origin flowing into the Arctic
Ocean, than is incoming water of Atlantic origin.
Therefore, the primary production of the sector of thein lateral nutrient supplies and primary production.
Furthermore, the loss of sea ice and a general increase in
the frequency and intensity of cyclones in the Arctic may
cause episodic nutrient supplies, resulting in periodic
increases in primary productivity (bloom)26. On the other
hand, the decrease in sea ice and brighter seawater column
may restrain the increase of microalgae27 that are adapted
to darker places, for example, algae in the brine28 of sea
ice and phytoplankton under the sea ice. Moreover, therapid melting of sea ice may release ice algae to deeper
layers, thereby impacting benthic communities.
It is presumed that 20–50% of carbon fixed by primary
production in the Arctic Ocean flows into the food chain
called the microbial loop as dissolved organic matter, as it
does in other seas (Kirchman et al. 2009). In addition, theArctic Ocean requires attention to the following
combination of mechanisms supplying organic matter:
1) Inflow of a large amount of dissolved organic matterfrom rivers,
2) Addition of organic matter from melting ice, and
3) Infusion of organic matter inflow from marginal seaswith high productivity.
About the latter in particular, water of Pacific origin thathas passed over the Chukchi Sea shelf, a region of highprimary productivity, supplies organic matter to the
Canada Basin, thereby maintaining a layer of highbacterial productivity on the Alaskan side of the Arctic(Uchimiya et al., 2013). However, little is known about
the Siberian side, where a large amount of terrestrial
26

Bloom: A phenomenon of explosive growth of phytoplankton caused by the combination of excessive nutrients, plentiful sunlight and suitabletemperature.
27
Ice Algae: The alga that thrives and spreads on the bottom or inside of sea ice.
28
Brine: Water of very high salinity and high density. In the ocean, it is formed by the rejection of salt from water freezing to form sea ice. The
accumulation of rejected salt creates brine that is increasingly resistant to freezing. When released into the water column, its high density causes it tosink to the bottom, unless mixed.
29
Denitrification: In oceans, the phenomenon in which mainly nitrate nitrogen NO3- is reduced to form nitrogen gas (N2) or nitrogen oxide (N2O) by
the function of bacteria in sea-bottom sediment, and then released to the atmosphere in gaseous form.

33

international collaboration. At the same time, it isimportant to show Japanese originality by analysis ofmany items that Japan is able to provide high-quality data,
and that Japan leads by cooperation with satellite
observation and study with models.
It is expected that new findings on biogeochemistry andecosystems will be obtained by adopting new techniques,by pushing forward the development of chemical andbiological sensors and observation platforms, and byadvancement of satellite observation (refer to Theme 9 on
the maintenance of the study base). Regarding thechemical and biological sensors, we will determine
seasonal variation by attaching them to mooring systems,
and by measuring the microstructure of chemical andbiological properties (not able to be measured before) byattaching them to a CTD and turbulence meter. Then weshould be able to discuss the origin and formation of new
water masses. In addition, quantitative analysis of thecycles of nutrients (carbon, nitrogen, and trace elements)
will be enabled by estimating their flux in conjunction
with measurement by physical sensors. Chemical andbiological observations, in open ocean and also on orunder sea ice, may be enabled by sensors on profiling
floats, on underwater gliders, on autonomous diving
machines, and by mounting water sampling devices onthem. A system that can observe the flux of nutrients,
methane, and trace elements between the bottom sedimentand the water just above the bottom, is also necessary forunderstanding the biogeochemistry of the continental
shelf area, and for understanding shelf-basin interaction.
Data from satellites, particularly about the distribution ofchlorophyll-a (Chl-a), is indispensable to understanding
the Arctic Ocean ecosystem. However, there are problems
to be overcome, such as the loss of data due to cloud cover,overestimates of Chl-a caused by colored dissolved
organic matter (CDOM) from rivers, and poor estimatesof subsurface Chl-a maxima. If we are able to obtain timeseries data over more extensive regions in the future, thiswill become a strong tool by which to answer the questionof how biogeochemistry involved in ocean ecosystems in
the pan-Arctic seas, changes.

Arctic Ocean most influenced by the Pacific Ocean islimited mainly by nitrogen. On the other hand, when sea
ice forms over the continental shelf in winter, iron that isessential to primary production is packed andconcentrated in the sea ice, and is transferred with the sea
ice. In addition, iron derived from sediment on thecontinental shelf becomes abundant in the dense shelfwater (DSW) 30 made by brine rejection during theformation of sea ice, and is transferred to the continental
shelf slope with DSW. Trace elements may also be carried
to the Arctic Ocean by aerosols. It is thought that thecycling of nitrogen and trace elements changes withenvironmental variation, and that this is a key factor
controlling future primary production in the Pacificinfluenced sector of the Arctic Ocean.
b. Future studies
It is necessary to acquire observation data that have noregional or seasonal biases in order to clarify the cyclingof carbon, nitrogen, and trace elements, as well as thechanges related to them, in the Arctic Ocean. This will
also contribute to understanding of the roles of the panArctic region in the global climate system. For this, thereis need for observations carried out by multiple vessels,with international collaboration, to acquire the desired
data over broad areas. It is expected that mesoscaleobservation will be able to resolve ocean eddies, but,because time is limited, it is necessary to focus on thetarget areas now using satellite observation and numericalmodels. Until now, Japan, the United States, Canada,
Russia, China, and Korea have contributed to theDistributed Biological Observatory 31 and carried out
repeated observations in the Chukchi Sea using multiple
ships. Japan and Canada jointly observed a wide area of
the Canada Basin, and have also contributed to theresearch results described previously.
There are still data blanks, particularly on the Siberianside of the Arctic Ocean, within the Russian EEZ, where
the most dramatic biogeochemical changes in the world
occur. In addition, data are insufficient in the region of theCanadian Archipelago where thick ice prevents in-vessel
observation. Furthermore, it is necessary to acquire datathat are not provided by summer ship observations, byobservation from winter ice camps, and by long-term
observation using sediment traps32 and mooring systems33.
It is also necessary to evaluate quantitatively the
relationship between ecosystems and ocean acidification,by performing culture and breeding experiments, bynumerical modeling, from comparison of data from shipobservations, and by use of sediment trap and mooring
systems. These research activities are expected to be incooperation with projects such as RUSALCA 34 or
AODS 35 in the future, and to be carried out with

30
Dense Shelf Water (DSW): Water of high salinity and high density (see Brine) formed at the time of sea ice formation during winter cooling on thecontinental shelf.
31
Distributed Biological Observatory (DBO): US-led international project using multiple research vessels to understand marine environmental
changes in the Chukchi Sea, Arctic Ocean < http://www.arctic.noaa.gov/dbo/index.html >.
32
Sediment trap: A funnel-shaped sampling device used to gather settling particles in seawater.
33
Mooring system: For research, an observation system anchored by heavy weights on the seabed, which floats in seawater, from which sensors areable to measure currents, water temperature, salinity, and other physical, chemical and biological characteristics.
34
RUSALCA (Russian-American Long-term Census of the Arctic): US-Russian collaborative hydrographic experiments in the Chukchi and East
Siberian seas <http://www.arctic.noaa.gov/aro/russian-american/>35
AODS (Arctic Ocean Drift Study): International project to scale-up observations and modeling studies to include the Arctic Ocean and sub-polarseas. This is an integrated effort involving a) ship-based cross hemisphere transit sampling; b) three in situ ice camps: one in the Eurasian Basin, one
at the ice exit of the Fram Strait, and one in the Southern Beaufort sea ice gyre; and c) a Lagrangian autonomous ice-drift program designed toconnect process studies from ‘a’ and ‘b’, and to extend observations to cover a full annual cycle.

34

Theme 4: Ice sheet / glaciers, permafrost, snowfall / snow cover and hydrological cycle
Abstract

situ observation and satellite observation need to be
developed. Specific objectives should include
improvement of the accuracy of observations of winterprecipitation, snow quality and impurities/biologicalcomponents, as well as improvement of the snow-covermodel.
Study of the hydrological cycle in the Arctic region,
including land, atmosphere and ocean, is proceeding ineach research field, but the current understanding of theinterrelationship between the fields is inadequate.
Continuation of land and satellite observations, andsynthetic study done under collaboration of terrestrial,
climate, hydrological, and ocean modeling is necessary.
With more data and insights, may come chances to clarify
the influences of frozen ground, snow cover, vegetation,
rivers, and meteorological conditions on the hydrologicalprocesses in the pan-Arctic terrestrial region, and on thesea-ice formation and material cycle in the Arctic Ocean.
Q1: Will the change in ice sheet and glaciers accelerate?
Q2: How will the permafrost change interlink withclimate change?
Q3: How is the snowfall and snow cover of the Arctic
Region changing?
Q4: How will the hydrological processes in the Arctic
change?

Change to glaciers and ice sheets in the Arctic region
affects the regional climate and hydrological cycle, andfurthermore, has effects on the global-scale environment
including sea level and albedo. Strong collaboration
between in situ/ satellite observation and modeling isimportant in order to clarify the variation mechanism andto improve projections into the future. Moreover,understanding of phenomena such as interaction between
calving glaciers and the oceans, and the influence ofcryosphere biology and ice quakes also need to beadvanced.
Change in the surface layer of permafrost (active layer)
is strongly related to snow cover and soil moisture, in
addition to warming in the area. When the active layer
reaches the level of permafrost ice and melting proceeds,
irreversible thermokarst occurs, and resulting in feedback
to the climate system through ecological and hydrologicalprocesses. In order to clarify these changes, research
schemes based on integration of existing permafrostobservation networks, observation of land-surface
processes, and support of satellite data and modeling, will
all be needed.
Snow cover in the northern hemisphere is decreasing,
especially in spring. However, existing information onquantitative and qualitative conditions is insufficient.
Integrated research schemes, consisting of combined in

Q1: Will the change in ice sheet and glaciers accelerate?
the terminus comes in the form of calving. Since a numberof calving glaciers exist in the Arctic, and they show
relatively larger changes compared with non-calving
glaciers, calving there contributes significantly to ice loss.

a. Background of the research(1) Mass change of the Greenland ice sheet and its
mechanisms
Greenland holds 10% of the ice on Earth. The ice mass
showed clear decrease after year 2000, and the loss ofmass has been accelerating (through 2010). The rate ofmass loss was 200 Gt a−1 from year 2000 to 2010, and thisis equivalent to a sea-level rise of 6 mm annually(Shepherd et al., 2012). The change in mass occurs mainly
due to the following processes.
(1) Accumulation due to snowfall(2) Loss due to melting(3) Ice loss at the terminus of the calving glacier (loss due
to iceberg runoff and melting by the ocean)
From recent observation, the contribution of (2) seems
to be predominant, but (3) seems to be increasing. On theother hand, (1) also seems to be increasing, but not enoughto compensate the losses from (2) and (3).

(3) Reconstruction of present ice sheet/glacier change
by numerical model
Numerical models to simulate ice sheet/glacier are
generally composed of various sub-models. The models
are usually simplified depending on the objective of the(2) Mass change of glaciers/ice caps (GICs) and its
mechanisms
The GICs in the Arctic are distributed widely in Canada,
Greenland, Alaska, and the Russian and Svalbard
Archipelagos. Their total mass is estimated to be 200 to
300 mm sea-level equivalent. This amount is smaller thanthe Greenland ice sheet, but due to the rapid change inthese GICs, they are considered important for sea-levelrise. In particular, changes from 2003 through 2009 inthree regions (Arctic Canada, Greenland area, and Alaska)
were especially large, and accounted for more than half of
the world glacier mass loss during that period (Gardner etal., 2013). Changes in mass are determined mainly by thebalance between snowfall and melting, and mass loss at

Photo 1: Calving glacier flowing from the Greenland Ice
Sheet to the ocean (Photo: Shin Sugiyama)

35

Under the present warming conditions in the Arctic, themass of the GICs there is expected to decrease. Because
the GICs respond more quickly to climate change thandoes the ice sheet, it is important to estimate its future rateof mass loss. It is not clear whether the previous rapid lossof mass continues at the calving glaciers, which arepresently showing large changes. This is partly because
the interaction of calving glaciers with the ocean is poorly
integrated with knowledge of the ice sheet.

study, the glaciers of interest, and the predominant
processes involved. Although a high-resolution glacierflow model using full Stokes equations became applicabledue to the effort of Japanese scientists in recent years,
numerical experiments covering extended periods, such as
glacial-interglacial cycles, is still difficult. At the present
stage, computationally less expensive models are madeusable by assuming relatively simple approximations of
ice dynamics. The most important uncertainties in thecalculation of glacier flow, involve basal sliding andcalving. Presently, empirical methods are used for theseprocesses since observations are difficult.

(2) Uncertainty of influence on sea-level change andeffort for estimation
It was pointed out that GICs have a larger influence on
sea-level change than do large ice sheets. Accurate
estimation of the extent of GICs all over the world isdifficult, but more and more reliable numbers are being
reported, based on gravity measurements and elevation
measurement by ICESat (Gardner et al., 2013). These
results showed that the recent mass loss of GICs in the
Arctic has had a relatively large influence on sea-levelchange. Ice mass loss is large particularly great in Arctic
Canada, Alaska, and the Greenland coastal area, which
accounts for a significant portion of global mass loss from
GICs. Therefore, it is necessary to observe these changes
at high resolution, and to be able to predict future changes.
In recent years, glacier mass change has been calculated
globally based on regional mass balance andparameterization of glacier area and volume.
The contribution of the Greenland ice sheet to sea-level
rise is also increasing, as shown by satellite observations.
There are projections of ice-sheet-mass loss using
numerical models, such as those based on surface-massbalance calculation (generally assuming fixed ice-sheet
dimensions), and those coupled with ice-flow models. For
example, the contribution of the Greenland ice sheet to
SLR was estimated to be 2–13 cm from 1980 to 2099, by
Yoshimori and Abe-Ouchi (2012). It is projected to be 16
cm by year 2100, by those of the Ice Sheet Intercomparison Project (SeaRISE), using a warming scenario
equivalent to RCP8.5.

(4) Influence of the growth of glacier microbes on ice
sheets and glaciers
The albedo of snow and ice surfaces has decreased in
the Arctic due to the activities of microbes, resulting inincreased melting on ice sheets and glaciers.
Photosynthetic microbes such as cyano-bacteria and green
algae live on the glacier surface even in cold environments.
The organic matter made by these microbes changes todark humus, which along with mineral particles, soot, andmicrobial remains, may form cryoconite, a dark material
that may concentrate on the surface of glaciers. When thisdark cryoconite is plentiful, it lowers the albedo of theglacier surface (Takeuchi et al., 2001). Albedo lowering
was studied in Asian mountains mainly by Japanese
researchers, but it has been found, in the recent years, tobe affecting the bare ice area of the Greenland ice sheet(Yallop et al., 2012).
(5) Increase of glacial earthquakes
Glacial earthquakes are seismic events accompanying
glacial sliding, ice fractures, and calving from theGreenland ice sheet, especially at its periphery (Ekstrom
et al., 2006). Since the frequency of glacial earthquakes
has increased recently, and their occurrence shows
seasonal variation, it is assumed to be associated with melt
water flowing onto the bases of glaciers. This appears tolubricate and thus increase the speed of a sliding glacier,and consequently increase the rate of calving at its
terminus. The frequency of glacial earthquakes peaked in2005 and decreased afterwards, but is now increasing.
This increase is more significant in the northwesternregion of the ice sheet, according to measurements inwhich Japanese researchers are taking part.

(3) Interaction between the ice sheet and ocean/solid
earth and influence on the acceleration of calving fromglaciers
There is a need to understand the interaction between
the ice sheet and the ocean, due to the strong acceleration
and recession of the calving glaciers in Greenland. Recent
observations on the Greenland coast suggested that a risein ocean temperature is driving the change of calving
glaciers. Furthermore, melt-water discharge from the icesheet changes ocean currents, and sediment and chemical
inclusions in the melt-water affect the marine ecosystem.
Key processes controlling change of calving glaciers
include forcing from the ocean to the ice-sheet (e.g.,
melting of a glacier in the ocean at the calving front), andin turn, forcing from the ice-sheet to the ocean. Theseshould become more significant if the ice-sheet masscontinues to decrease.
Glacial earthquakes in Greenland were identified in the
21st century, but remain poorly understood. By better
understanding this mechanism, the frequency and mode ofglacier earthquakes might be used to study glacier
dynamics. Further studies will enable us to findrelationships between on-going climate change andtemporal variation of glacier-earthquake frequency, and toprovide new information related to other glaciological,

b. Key Question: Will change in the ice sheet andglacier accelerate?
(1) Uncertainty in the mass loss of the ice sheet,glaciers and ice caps in the future
The future variation of the Greenland ice sheet isdetermined by the amount of snowfall, the amount of
melting (snow and ice), and the amount of calving from
calving glaciers. Melting is considered to be increasing
due to the temperature rise in the Arctic and albedo
lowering of snow and ice surfaces. On the other hand, theestimation of future snowfall, and the frontal ablation ofcalving glaciers, is not clearly understood. Snowfall might
increase in response to the warming climate, and might
exceed the mass loss from surface melting and calving.
There is also a possibility that the on-going acceleration
and recession of calving glaciers will end at some time in
the future. Uncertainties related to ocean temperature andcirculation also complicate evaluation of future changes in
the mass of the ice sheet.
36

observations are indispensable for validation andimprovement of numerical models. Bed geometry, surface
mass balance, and flow velocity data are particularly
important for further development of numerical models.
Numerical modeling is important for studies on the ice
sheet as well. Adequate development and improvement ofmodels is needed, that relates to the temporal and spatial
scales under consideration. Key issues in the field of icesheet modeling include(1) Calibration of models by comparison of modeled
and observed, present-day ice-sheet geometry,(2) Improvement of processes related to surface-massbalance,(3) Improvement of basal hydrological processes andice flow, and(4) Coupling with Earth-system models, including
ocean and solid land.
Observational data should be used effectively for thecalibration of the models. It is also important to include
adequate interaction between climate and the ice sheet, inorder to reproduce global-scale climate and ice-sheet
variations (Abe-Ouchi et al., 2013). Effort is needed toreproduce accurately changes in surface-mass balance,
and interactions between calving glaciers and the ocean(e.g., melting of ice fronts in the ocean). For example,
estimates of surface-mass balance could be improved bydeveloping a regional meteorological model of Greenland,
using observational data.

meteorological and geophysical processes. By
comparison and coordination of glacial earthquake datawith climate modeling and paleo ice-sheet studies, theeffect of climate change on the Greenland ice sheet may
be assessed more accurately.
(4) Ecological change of ice sheets and glaciers and its
influence on albedo and ice flow
Albedo decreases under the influence of red snow
phenomena, caused by the occurrence of green algae. Thisenhances snow surface melting, not only in the ablation
area of glaciers, but also in areas of accumulation andseasonal snow cover. Such albedo decrease due to snow
microbes is not as well understood as for black carbon(soot) and mineral dusts, but microbes may also acceleratechange of the Arctic ice sheet and glaciers. Therefore,
there is a need to advance our quantitative understandingof the influence of environmental change, such as global
warming, on the ecological conditions on glaciers, andspecifically, their influence on the albedo of the snow
surface.
c. Future ice sheet and glacier studies (direction,
content and method)(1) Quantification of the ice sheet and glacier changes,
and understanding of the driving mechanisms, using
in situ and satellite observations
Satellite measurements are the most effective method
for monitoring both the Greenland ice sheet and the GICs
there. Detailed measurements of surface elevation
changes are possible using DEMs generated fromstereographic visible-image pairs and SAR data, as well
as satellite altimetry. Changes in the position and areal
extent of each glacier terminus can be detected in satellite
images. Furthermore, the speed of ice flow can bemeasured using the image correlation method orinterferometry of SAR images (InSAR), and change in ice
mass can be measured using satellite gravimetry.
Technical development of satellite sensors in Japan has
contributed to these satellite observations, and it isimportant to continuously develop sensors and improvedata processing tools for future observations.
Field measurements remain important because of thehigh temporal and spatial resolution of in situ data. In fact,many measurements are possible only in the field (e.g.,
englacial and subglacial measurements and sampling).
Furthermore, in situ data is important for calibration ofsatellite data and as input data for numerical models. Moreefficient and higher quality measurements are required forthe northwestern part of Greenland, the Russian Arctic,
and Alaska, where Japanese researchers worked actively
and achieved progress, in the past.

(3) Ecological change on the glacier and its influenceon climatological components
Studies on the quantitative evaluation of the growth of
microbes, and its effect on decreased albedo, are necessary
to explain the accelerated melting of glaciers and snow
cover by the activities of snow microbes. First, a microbial
growth-process model should be developed based on thephysical and chemical conditions of snow and ice surfaces.
Next, the optical characteristics of microbial products
should be measured and then included in a snow/ice
albedo physical model, together with black carbon anddust. Such an albedo model could be used to computeaccurately the heat balance at the surface of a glacier, andits mass budget. Along with such studies, long-term
satellite observations on spectral reflectance, and in situ
monitoring of microbe communities, are also needed tomonitor temporal variations of surface albedo andmicrobial growth.
(4) Status and projections of the interaction between
ocean and ice sheet
The importance of the interaction between theGreenland ice sheet and the ocean is recognized. However,more observations are needed on the Greenland coast to
develop a system including both in situ and satellite
observations. The physical properties of ocean water,
ocean circulation, and sea-ice conditions in the fjords ofthe calving glaciers are especially important; because they
are suspected of being the drivers of recent rapid variationof glaciers. Cooperation with polar oceanographers is
crucial for installing mooring buoys, and for measurement
and sampling by research vessels. Furthermore, moresatellite observations and better numerical modeling ofcoastal ocean processes are needed as well.
The Greenland Ice Sheet monitoring Network;(GLISN), a long-term seismic monitoring program on theice sheet, was organized by an international research(2) Improvement of the numerical modeling of the ice
sheet and glaciers
Numerical modeling of glaciers requires adequate
development and improvement of models according to theobjectives of the study. Simplification andparameterization are essential to manage the number ofglaciers needed to estimate the influence of the masschange of Arctic glaciers on sea level. On the other hand,refinement of process models and higher-orderassumptions are needed, in order to estimate glaciervariations more accurately, and to understand themechanisms causing abrupt changes of calving glaciers.
Coordination between satellite-data analyses and field
37

the ice sheet, and to describe related fault parameters, by
the determination of accurate hypocenters and earthquake
mechanisms. Herein is a unique opportunity to study the
influence on global warming of glacier earthquakes andtheir mechanisms. New data sets and interdisciplinary
viewpoints will be provided to study the response of theGreenland ice sheet to climate change.

group as a program for the post-IPY period. Japanese
researchers had already established a seismologicalobservation site (ICE-S) on the ice sheet in 2011, incooperation with the earthquake observation network of
the USA (IRIS) (Toyokuni et al., 2014). We will enhanceglacier-earthquake-monitoring activity by integrating ourdata with those of the GLISN observation network. These
data are used to position the origins of earthquakes within

Q2: How will the permafrost change interlink with climate change?
reason is possibly due to intensified freezing caused bydecreasing snow depth in winter, and drying of the soil insummer, which suppresses thawing (Park et al., 2013). On
the other hand, the ALT is getting deeper due to warming
and increased snow depth in Siberia (Park et al., 2013).
The variation in ALT depends much on hydrologicalconditions, such as snow depth and soil moisture, as wellas temperature variation.

a. Background(1) Permafrost change due to global warming
Permafrost is defined as soil or ground that remains
below the freezing point for at least two consecutive years,
and this condition exists on 20% of global land. In contrast,
soil that freezes in winter and thaws completely in summer
is called seasonal frozen ground, and this condition exists
on 60% of global land. Temperature observations during
recent decades indicate a general trend of warming
permafrost. This warming (increased temperature) has
been greater in severely cold regions with continuous
permafrost zones at high latitudes. There are sites in the
Russian and Canadian Arctic, where the increase has been
more than 1 °C per decade. Strong temperature rise, andthawing of permafrost, is occurring at discontinuous andsporadic permafrost zones at their southern limits, and theboundary between continuous and discontinuous
permafrost is tending to shift northward (Romanovsky etal., 2010).

(3) Active layer variation and hydrological / ecological change
Variation in the active layer induces change inecological and hydrological processes. When ice-richpermafrost melts, and the melt-water is discharged, a formof land subsidence called thermokarst occurs.
Subsequently, lowlands expand and extensive regions ofthermokarst lakes are formed. The formation ofthermokarst lakes is presently active in the continuous
permafrost zone, while lowering of the groundwater level,with drying due to disappearance of the permafrost, istaking place in the discontinuous zone. Increased collapseof landforms facing rivers and coastal areas has beenreported in the continuous permafrost zone of North
America. This is caused by increased soil instability due
to melting of ground ice (Jorgenson et al., 2006).
In Eastern Siberia, the ALT has deepened in the first
decade of the 21st century (Iijima et al., 2010). This ismainly due to high winter snowfall and summer rain
occurring continuously for several years. This hasenhanced thawing of the surface layer, and kept a highlevel of soil moisture within the active layer. Subsequently,
the ALT became deeper, and extensive death of larch trees
occurred because of the greatly increased water content
within the active layer (Ohta et al., 2014).
In the 2000s, the soil moisture level in East Siberia
increased by ca. 10 mm per year, based on GRACE
satellite data (terrestrial water storage estimated by gravity
change measured by twin satellites, Ogawa et al., 2010).
Thus, this inter-annual trend is likely due to increase in thenumber of thermokarst lakes, and of soil moisture within
the active layer, in regions of boreal forest.

(2) Deepening of the active layer
In permafrost zones, the surface soil layer that freezes
in winter and thaws in summer is called the active layer.
The active layer thickness (ALT) is approximately 0.5 and1.5–3.0 m in the continuous and discontinuous permafrost
zones, respectively, in Alaska, and 0.4 and 1.0–3.0 m in
the tundra and taiga areas of the permafrost zone in
Eastern Siberia. The ALT depends greatly on the summer
air temperature (accumulated warmness), and snow depth
in the winter. The long-term tendency of ALT differs
among regions. For instance, it is getting shallower,
despite rising air temperature, in North America. This

(4) Observation system for the active layer
The measurements of permafrost temperature and ALT
are presently conducted in the pan-Arctic by the GTN-P(Global Terrestrial Network for Permafrost) and CALM
(Circumpolar Active Layer Monitoring Network).
However, the present pan-Arctic network is insufficient interms of integrated observation sites that could supply
data adequate for understanding comprehensive
interactions between conditions affecting permafrost,climate, soil and vegetation.

Photo 2: Thawing of permafrost around the alas(thermokarst lake) near Yakutsk, Eastern Siberia (Photo:
Yoshihiro Iijima)

38

permafrost zones. Recent climate change also induces
different patterns of precipitation and evapotranspiration.
This affects the terrestrial water balance through change
in the thermal regime within the active layer. Since
permafrost and the active layer, act as a buffer layer
affecting soil moisture and ground water transfer,variation of the water balance at the land surface shows acertain time lag, in relation to the atmospheric water cycle.
For example, gravity change data from the GRACE
satellite showed an inter-annual anomaly of terrestrial
water storage in the surface layer, with one-month
temporal resolution and several hundred km spatial
resolution. However, understanding the permafrosthydrological process is hindered by a lack of the in situ
observations needed to resolve the heterogeneity of thepermafrost structure at river-basin scale.

b. Key question: How will permafrost change inconjunction with climate variation?
(1) What and how does active layer thickness change?
Earlier spring thaw, and later autumn freezing,
effectively manifest variation in ALT under conditions ofwarming air temperature. The ALT is also affected by thetiming of the disappearance of snow cover in spring, andby changes in soil moisture due to summer precipitation.
An ice-enriched layer, ranging from several tens of cm to
1 m, is formed at the boundary between the active layer
and the lower permafrost layer, because this zone provides
physical conditions favorable for ice growth. This layer iscalled the transient layer, and may alternate from thawing
to freezing over sub-decadal to centennial time-scales(Shur et al., 2005).
This transition layer exists between the active andpermafrost (Yedoma) layers, and is typified by thepresence of a large ice body (ice wedge). The thermokarst
process involves melting of soil ice and subsequentsubsidence, but tends to be delayed in places with atransient layer, since more latent heat energy is needed tothaw the ice wedge. However, after the entire transientlayer is thawed, an irreversible process of melting
permafrost will be manifested. Thus increasing heat
conduction, due to changes in climate and environment,
leads to abrupt deepening of the active layer. However, we
do not have enough observational data yet to illustratethese degradation processes.

c. Future study on surface variation of permafrost:
Direction, content and method(1) Understanding the evolution of the active layer andthe thermokarst development process
Identification of the spatial distribution of soil moisturedynamics in the active layer, and ice content in thepermafrost layer, is indispensable for discussion of thestability of change in the active layer, and thawing of thepermafrost under conditions of Arctic warming.
Measurement of soil temperature is basic practice formonitoring permafrost, but we should refine it to include
measurement of the active layer, transient layer, and upper
part of permafrost; and then add sites over an expanded
area, to better depict the extent of thawing. Obviously, themoisture conditions in the active layer and ice content in
the permafrost layer need to be measured as extensively
as the soil temperature. Sample cores from the nearsurface layer of the permafrost are also important formaking clear the range and frequency of ALT variation in
the past by glaciological analysis, stable isotope ratio andchronological analysis. Prompt implementation of in situ
survey measurement of ground subsidence andmorphological change are also needed.

(2) Influence of the melting and deepening of the active layer
We should pay attention primarily to clarification of
feedback processes induced by “warming of thepermafrost” and “deepening of the active layer” as thepermafrost portion of the environment changes. These
appear to have occurred during the past one or two
centuries, and see likely to continue through several tensof years into the future. Most environmental change(increased runoff, decline of boreal forest, and emission of
methane gas from expanding lakes) that occurs inconjunction with the occurrence of thermokarst in the panArctic region, will all be caused by “deepening of theactive layer”, and a great deal of observational knowledge
has been accumulated. For example, near-surface
permafrost has become ‘talik’ (a non-freezing layer
throughout the year) due to deepening active layers invarious areas of Siberia (Hiyama et al., 2013). Key
research to clarify the influence of changes in permafrost
on climate change should therefore, aim to understand thesuccessive processes of permafrost in the larger ecohydrological system. These would be expected to inducechange in the distribution of water (areal and depth) andwetlands. Such a case was recently reported in Eastern
Siberia; that is, extensive boreal forest mortality induced
by deepening and wetting of the active layer, due toincreased precipitation.

(2) Understanding of the influence of active layer deepening
on the surface environment, hydrological cycle, and climatechangeContinuous observation at an integrated observationsite (super-site), and refinement of land surface models
based on those data, are needed in order to understand howchanges in near-surface permafrost, and the active layer,
affect the surface environment and how these changes
feed back to the climate system via changes in the heat,water, and carbon balance. Satellite remote sensing andapplication of regional land surface models, are effective
for understanding the related phenomena of extensive
active layer deepening induced by forest fire, and climatechange (wet and dry anomaly). Temporal and spatial
variation of permafrost thawing, may be indirectly
detected using satellite data obtained from microwave andoptical sensors, to quantify devastation of vegetation from
active layer deepening and thermokarst development. The
latter affects variation in the area and number ofthermokarst lakes. However, satellite sensors that could
directly measure ALT do not presently exist. In the future,development of new satellite sensors and algorithms that
could estimate the sub-surface temperature profile isneeded, in conjunction with hydro-climatological study
through the development of synthetic analysis methods to(3) Relation between change in the active layer andlarge-scale hydrological cycles
Variation in ALT changes the vertical profile of soil
moisture, and thus changes the hydrologicalcharacteristics of the land surface. For example, regionalhydrological cycles and ecological systems would be
expected to be influenced by the drying of the surface
layer due to deepening of the active layer. In fact, a
substantial decrease in the area and number of lakes wasapparent at the discontinuous and southern limit of39

Simultaneous observation of meteorological, ecological,
and hydrological elements intimately related to active
layer variation needs to be established. Japan has taken aleading role in cooperative collaboration in Eastern
Eurasia, as well as international collaboration in Alaska
and the Canadian Arctic. These regions are possible areas
for intensive research where Japanese research groups
should contribute. Support of research by bilateral (orinternational) science agreements should be pushedforward for implementation of the above steps, to ease
efforts to access and set up infrastructure in each country.

detect variation in ALT by applying numerical models, insitu measurements, and satellite observations.
(3) Establishment of an integrated system forobservation of active layer variation
Measurement of permafrost temperature should follow
the guidance of GTN-P instruction. In addition, we shouldmake efforts to develop suitable instruments withdurability and accuracy appropriate for cold, remote sites.
There is need for a new network to cover key regions
where thermokarst processes are active and urgent needfor a standardized scheme for international observation.

Q3. How is the snowfall and snow cover of the Arctic Region changing?
and National Institute of Polar Research (NIPR) arecooperating in this project, and have set up observationsites at Jyoestu City, Niigata Prefect, and at Rikubetsu City,
Hokkaido.
On the Greenland Ice Sheet, surface elevation and ice
mass is measurable using satellite, but snowfall is only
measured by automatic equipment as a change of snow
depth. Deductions of spatial and temporal variation ofsnowfall is done using a model.

a. Background(1) Snow cover of the pan-Arctic region
The area under spring snow cover in the northernhemisphere, has decreased substantially in the latter halfof 21st century, especially after 1980. The extent of snow
cover exhibits differences in inter-annual variation,
depending on the month. Moreover, the degree ofcontraction (relative to previous coverage) is largest in
spring and summer, and differs regionally (Brown andMote, 2009). On the other hand, the extent of snow coveris generally decreasing, or showing no change, in the last
40 years in the southern hemisphere. The main cause of
the decrease in snow cover is the rise in temperature. Thisis both decreasing the snowfall and shortening the periodof snow cover, while increased precipitation is generally
the cause for areas showing increased snow cover (Lemke
et al., 2007).

b. Key question: How is the snowfall and snow cover changing?
(1) Temporal and spatial variation of the period ofsnow cover, snow depth and water equivalent
It is very clear that the duration of snow cover isshortening on the scale of the northern hemisphere.
However, more, and more representative, stations areneeded, since the variation of snow depth and snow-waterequivalent differs regionally. Setting up ground-based
observation sites, large-scale derivation from satellite
observation data, and their integration with predictions ofprecipitation by models, are all needed. It is thought thatthe reliability of observations of snow-cover distribution
and areas of ablation is high, but the reliability of snowwater equivalent is still low, in spite of the developmentof microwave satellite-observation methods. The
derivation of the amounts of snow in forested areas
remains an unresolved issue.

(2) Observation accuracy of high latitude precipitation
The precipitation data lack reliability in the Arctic
region due to low number of stations and low accuracy ofobservations. Clearly, improvements need to be made(Goodison et al., 1998). The satellite for the GPM Project
was launched in February 2014, and estimation of
precipitation is expected to improve for regions up to 65
degrees north. In particular, the data for southern Siberia
and southern Alaska should be improved. A project called
SPICE (Solid Precipitation InterComparison Experiment),of the WMO, was implemented to operate from 2013 to2015, to clarify the present condition and to improveobservation accuracy of snowfall and snow cover. The
Japan Meteorological Agency (JMA), National ResearchInstitute for Earth Science, Disaster Prevention (NIED),(2) Quantitative evaluation of snow impurity, snow
texture, and microbes
Quantitative evaluation of snow impurity, snow texture,and microbes have only been undertaken at several sites,
and only as case studies. There is a need to understandobservations of these factors at an Arctic scale. Based onsuch necessity, research directed to derive snow impurity
and grain size from satellite observations is being done,
but more land-based calibration data need to beaccumulated.
(3) Interaction between snow cover and changes in thealbedo of soil, ecological systems, and the atmosphere
Winter precipitation is not decreasing, although adecrease of snow cover in spring is occurring. This meansthat snowmelt is intense in springtime. Furthermore, anincrease in atmospheric water vapor due to sublimationfrom snow-covered areas is indicated (Sugiura and Ohata,2008). As for the study on the interaction between snow
cover and changes in the albedo of soil, ecologicalsystems, and atmosphere, integrated in situ observation of
precipitation, snow cover and land-surface processes is

Photo 3: Snow cover over which depth hoar layer developed
at a forest site in Siberia (Photo: Yoshihiro Iijima)

40

with the ecosystem through ground-based observation of
the heterogeneity of snow distribution around vegetation,using interval cameras that have recently come into use.
Also needed is clarification of the interactions between
vegetation, soil, snow cover, snowfall and atmosphere,
using high-precision, multi-element data, and using thesedata for calibration of numerical models. As for numericalmodels, the most pressing need is to improve the snowcover models, and combine them with meteorological,
ocean, and soil models. There is a need to clarify thefactors determining snow texture, and these need to bereflected in the snow cover model. Satellite use needs tobe advanced, and standard products from snow parameters(i.e., water equivalent, canopy intercepted snow, snow
texture, and impurities) should be prepared. As forground-calibration data, improvement of the precision of
estimates of snow-water equivalent, particularly inforested regions, is needed.

needed, along with integration of this new data withmodels.
c. Future study of snowfall and snow cover: Direction,
content and method(1) Observation and modeling of snowfall and snow cover
There is need to initiate high-accuracy measurement ofprecipitation (especially snowfall), along with thephysical parameters of snow cover for the Arctic Ocean,tundra, boreal forest, glaciers, ice sheets, and ice caps.
Then, this data should be combined with satellite data todevelop a long-term data archive. There is also a need todevelop calibration methods by which past data might also
be included in the new data archive. Through these
activities, it is possible to understand better past changes
in precipitation and snow amount, to prepare boundary
conditions, to calibrate climate models, to develop
analysis algorithms for satellite data, and to create newsatellite sensors suitable for snowfall and snow-coverobservation. There is a need to combine the data from new
precipitation satellites, such as GPM/DPR, and to improvemethods for assimilating atmospheric data, in order toestimate global precipitation by satellite.
Hydrological components involving strong wind andforested areas could be measured by technicaldevelopment of new observation instruments, andhydrological conditions of the winter cryosphere could beclarified through these efforts. As for snowfall, data overshorter intervals (intensity over hours and minutes) andautomatic observation of snow particles are needed. Thereis need for increased number of automatic observationsites that use lasers for the measurement of snow depth.
There is also need to proceed with study of interactions(2) Snow on sea ice
Snow on sea ice is a factor deeply related to the growthand melting of rapidly changing sea ice. There is need tounderstand the role of snow cover and the metamorphismof snow and ice, and to develop observation methods todetermine large-scale snow cover. The snow on sea ice isimportant from the standpoint of apparent thickness,albedo, and thermal conductivity. The satellite
observation method for snow on sea ice has not advanced
much, and new methods are needed. The snow on sea ice
influences the accuracy of observations of apparent seaice thickness, so there is need to establish methods forboth in situ and satellite observations.

Q4 How will the hydrological processes in the Arctic change?
atmosphere. In this case, the contrast in meridionaltemperature, between the Arctic Ocean and thesurrounding land area and also associated atmosphericcirculation will be changed.

a. BackgroundIn the Arctic terrestrial region, permafrost, snow andboreal forest play key roles in the hydrological cycle.
Rivers in the Arctic are sources of freshwater, nutrients,and organic matter for the Arctic Ocean. An abrupt
increase in river discharge harms local residents due to ice
jams and summer floods, whereas it is a boon, due tonutrient transport, for people who live by farming or
fishing aquatic or marine stocks. In addition, changes in
the condition of river ice and permafrost, affecttransportation and living conditions in this region.
Therefore, changes in Arctic rivers have a large influenceon the lives of residents.
Change in the river discharge induces changes inmaterials of freshwater and terrestrial origin, and also
affects sea-ice formation, ocean circulation and material
cycles in the Arctic Ocean. The change in discharge iseffected by variations in precipitation associated withatmospheric circulation and various terrestrialhydrological processes within the river basin. The Arctic
terrestrial region located between mid- and high-latitudes
cannot be ignored in the climate system due to theatmospheric linkage between these latitudes. There isconcern that changes in terrestrial hydrological processes
will affect atmospheric circulation and weather over theregion. This is because there is a possibility that changes
in water and heat fluxes, and albedo, associated withterrestrial processes might affect temperature in the lower

Photo 4: Lena River in Eastern Siberia: Freshwater
gathering from major discharges into the Arctic Ocean(Photo: Yoshihiro Iijima)

41

al., 2010).
Under the condition of global warming, a large rise intemperature and increase in precipitation over the panArctic terrestrial region, will induce shortening of snow
duration, deepening of the active layer, and changes in thehydrological process that are expected to affect soil
moisture, evapotranspiration and vegetation activity. The
temperature rise will shorten the snow duration, and water
vapor increase due to the warming has the potential tochange evaporation, transpiration and sublimation in thedry continental inland of eastern Siberia. In fact, longterm increase of evapotranspiration was indicated byobservation and model studies (Zhang et al., 2009). It is
indicated that, in addition to snowmelt, sublimation is also
important in the process diminishing snow in eastern
Siberia (Suzuki et al., 2006). The precipitation increase
will promote deepening of the active layer and increase ofsoil moisture. The above terrestrial processes indicate thatsnow ice is a key factor in this region, and not only thehydrological processes, but also various processes
associated with heat balance, are important in the Arctic
terrestrial region.

b. Key Question: How will hydrological processeschange in the pan-Arctic terrestrial region?
(1) Change in river discharge flowing into the Arctic
Ocean and its cause
River discharge into the Arctic Ocean has increased inrecent years. This is because river discharge from Siberia
was large for several years in the latter half of 2000s,
although the change in Northern America was small. The
influence of dams, thawing permafrost and wildfire havebeen discussed as causes of the long-term change in riverdischarge, but the impact of all of these factors are
considered to be small compared with the recent changes
observed. River discharge is mainly governed by net
precipitation, which is the difference between
precipitation and evapotranspiration (Zhang et al., 2013).
The variation of net precipitation is affected by moisturetransport associated with synoptic-scale atmosphericcirculation and cyclone activity over the region. In
addition, terrestrial hydrological processes (e.g.,transpiration from vegetation, change in soil moisture dueto thawing permafrost) also affect river discharge. A
recent study indicated a relationship between summer
base flow and deepening of the active layer (Brusaert andHiyama, 2012), and a review of the terrestrialhydrological process is important for future work.
Climate models project precipitation increases overhigh latitudes under conditions of global warming, andriver discharge in the pan-Arctic region is also expected toincrease over the long term. Therefore, if freshwater input
into the Arctic Ocean increases in the future, so also will
heat, nutrient and organic matter. A change in theterrestrial hydrological process has the potential to change
the source of land-derived materials from the river itself(refer to Theme 3). However, there is large uncertainty inthe projections of precipitation increase and regional
distribution, and the survey of terrestrial processes at large
spatial scales is still not sufficient. There is need to discuss
future change, while clarifying the interrelations between
terrestrial processes.

(3) Freshwater budget in the Arctic Ocean andhydrological cycle in the Arctic
Increase of freshwater from the surrounding land area
strengthens salinity stratification at the ocean surface, andpromotes sea-ice formation due to the low-salinity waterlayer at the ocean surface. The increase of freshwatersupply will weaken deep-sea water formation on longterm timescales, since the freshwater into the Arctic
Ocean flows out through the northern Atlantic. To reveal
these processes, it is important to understand simultaneouschanges in sea-ice formation and ocean circulation in the
Arctic Ocean.
The amount of snow on the sea ice will increase underglobal warming, and this will strongly control theformation and melting of the sea ice. More direct input offreshwater as precipitation, due to rising temperature andexpansion of the area of seasonal sea ice, results in low
salinity at the surface of the ocean. However, there are few
studies about snow on sea ice, and there is need to observe
cloud, precipitation and snow-cover processes above theocean and sea ice (Theme 2). Considering the above
points, it is greatly needed to understand better thehydrological cycle, and to evaluate quantitatively thewater budget of the entire Arctic region. This should
specifically include the Arctic Ocean, pan-Arctic landarea, Pacific Ocean, Atlantic Ocean and the atmosphere
over these regions.

(2) Changes in hydrological processes in the panArctic terrestrial region
In the 21st century, snow depth (increased only in East
Siberia) has decreased over wide areas of the pan-Arctic
region, and some effect on soil moisture and river runoff
is expected. In fact, trends of increasing soil moisture over
North America and Siberia were observed by the GRACE
satellite (Landerer et al., 2010). In addition to the snow
amount, variation in the duration of snow cover is also
important. The snow duration tends to be shorter in recent
years, due to the delay of snow accumulation in autumn,
and the start of spring melting tends to start earlier, likely
mediated by the recent rise in temperature. The ability ofsnow to provide insulation that impedes heat transfer
between the atmosphere and soil affects soil temperatureand soil freezing. This effect results in changes in soil
moisture, phenology (seasonal changes in vegetation
activity), radiation, and surface-heat flux. There areregional differences in the effects from disappearance ofsnow. The difference in early summer albedo associatedwith snow, affects the radiation balance in western Siberia,
meanwhile summer snowmelt water affects the ratio ofsensible and latent heat in eastern Siberia (Matsumura etc. Future change in the hydrological cycle(1) Enhancement of terrestrial observation sites forbetter understanding of hydrological processes
For integrated utilization of the observation results, it isneeded to promote cooperation with those modeling. To
do this, there is need to prepare input datasets(meteorological elements), parameters (information onvegetation and soil), and validation data (groundtemperature, soil moisture, photosynthesis). In situ
observations in eastern Siberia have mainly been
conducted by researchers in Japan and Russia, and they
have produced substantial results. However, the winter42

provides an index appropriate for understanding thehydrological processes on various time and spatial scales,
and its use is an effective method by which to reconstructpast hydrological cycles. Although the discharge data in
the Arctic is limited in both period and sites, it is important
to continue these observations, and to elucidate thevariation of factors by means of water budget analysis,model research, and paleoclimate proxy-data analysis.
Ocean observation and ocean circulation models are
effective for evaluating the influence of river discharge on
the ocean. There is need to observe spatial and temporalchanges in freshwater input and output using mooringsand small vessels in coastal areas, and to examine therelationship between heat and materials of terrestrial
origin, and sea-ice formation. To evaluate the influence ofchanges in terrestrial hydrological processes on the
freshwater supply into the Arctic and Atlantic Oceans, theocean circulation, material cycle and ocean ecosystem; itis needed to take account of not only the main rivers, butalso freshwater and materials from small rivers, melted
water from ice sheets and glaciers, and groundwater.
There is also need to develop a sophisticated model thatcan reproduce realistic ocean circulation.

season has been an observational blank. To achieve yearround observation, there is need to set up and sustain asupersite at which variations of meteorological elements,
heat/water/carbon flux, frozen ground and soil moisture,
can all be measured. For that purpose, it is requested toestablish a bi-lateral or multi-national cooperative
structure, with a Japanese research institute responsible
for the observations. In Siberia, the candidate sites are
Sapasskaya Pad near Yakutsk, Elgeeii near Ust-Maya, andOl’okminsk along the Volyui River. A domesticcooperative research structure is needed to develop a longterm dataset of combined in situ observation, objective
analysis, and downscaling by regional models andsatellites, for validation of the hydrological cycle and of
extreme events.
(2) Observation of freshwater, organic matter, andheat transports from Arctic rivers, and development of
the ocean model
In order to elucidate the relationship between terrestrialhydrological processes via Arctic rivers, and oceanic
processes, there is need to set up observation sites in river
basins with different hydrological characteristics for themeasurement of the amount and timing of river discharge,
and of materials of terrestrial origin (refer to Theme A).
For projection into the future, there is need to reveal
factors determining the timing, quality and the place of
inputs of freshwater and materials from land into the
Arctic Ocean. This might be accomplished by combining
observations of precipitation, evapotranspiration, and soil
moisture with modeling. The stable isotope of water(3) Integrated understanding of ice sheets, glaciers,
permafrost, snow, and the hydrological cycle
For understanding large-scale hydrological variationthat cannot be covered by in situ observation, the use ofsatellite observation, terrestrial models, and objective
analysis of data is effective.
Since evaluations of water and heat budgets in the

Figure 16: Schematic diagram of the research on ice sheet/glacier, permafrost and snowfall/snow covervariation and hydrological cycle. [Theme 4]

43

Arctic on spatial scales such as continents and river basins
are insufficient, they are important research targets forlearning about the Arctic terrestrial hydrological cycle.
Recent satellite observations, such as terrestrial water
storage from GRACE, snow water equivalent fromAMSR2, the high frequency observation of precipitationfrom GPM/DPR, and high-resolution land-use
classification (e.g., water body) from ALOS and ALOS2
are useful for understanding and elucidating large-scalehydrological processes, and for validating models. It isnecessary to validate satellite products with in situ,
ground-based observations, and this demands continuousin situ observation, especially in the Arctic terrestrial
region, for which there is little ground data.
To understand realistic hydrological processes in theterrestrial model, adequate modeling of water infiltrationand heat conductivity in terms of permafrost,
improvement of snow cover, and snow-storm processes,
are required. Moreover, on long-term timescales (decades
or longer), a dynamic vegetation model is required, sincechanges in vegetation affect transpiration and soil
conditions. Integrated in situ observation covering thesecomponents are needed for validation of the model (refer
to Theme A).
Objective reanalysis data is important in climatechange research. Technical development of objective
reanalysis has been important for Arctic climate research,
for which in situ observation and expression by numericalmodels are restricted. While the present objective
reanalysis includes atmosphere and ocean, there is need todevelop techniques of data assimilation for a coupledatmosphere, ocean, and terrestrial climate system inconsideration of terrestrial processes. This would be
expected to provide a breakthrough for the study of thehydrological cycle in the Arctic.

44

Theme 5: Interactions between the Arctic and the entire earth

Abstract

large areas, and also the effects of variability inbiogeochemical cycles of soil, vegetation and permafrost,in the form of carbon flux and so on. The most active
research until now was conducted by field observations
and process modeling. However, further basic research isnecessary to provide quantitative estimates of the effects
of terrestrial processes on climate variability at large
scales, including the establishment of an assessment
method for the terrestrial processes. With regard to theupper atmosphere, the most important issues would be its
variability in the mid- and low-latitudes caused by anenergy injection into the polar region from the Sun
through the near Earth space, the cooling associated withincreasing greenhouse gases, and also the effects of thepolar upper atmosphere on the lower atmosphere. A
deeper understanding of the roles of the upper atmosphereon the climate system is expected by using ground-based
observation networks, satellite observations with multiple
sensors on a global scale, and numerical modeling with
the inclusion of photochemistry.
Following these approaches, we describe theinteractions among the systems introduced above, such as
the atmosphere, being remained challenging issues
continuously. The troposphere plays an important role in
the interactions, due to its location among the others. It
can interact with the upper side, the stratosphere and theupper atmosphere, as well as the lower side, the ocean andland. One of the examples referred to at the beginning of
this theme was the effect of the sea ice decrease on the
East Asian monsoon in winter, which could be led to the
feedback from the atmosphere to sea ice.
The effects of the Arctic variability appear in the midlatitude area, such as the Far East, where climate
variability is significant. The research community inJapan is supposed to play a major role in this subject. In
fact, the researchers in Japan have made a pronounced
contribution to understanding the effects of Arctic sea ice
on atmospheric circulation. We are expected toadvance our knowledge of the Arctic climate
system within the global climate system, on thebasis of this research achievement. As a result,more sophisticated and accurate prediction will
not be limited to the Arctic climate, but also
possible for the global climate.
This theme is formed with the five key
academic questions as follows:
Q1: Roles of the atmosphere: Is its variability
intensified or weakened for example, theArctic Oscillation?
Q2: Roles of the ocean: Is the water exchange
between the Atlantic and the Pacificintensified? Is the deep water formation
reduced? Is general circulation modified in
the mid-latitudes?
Q3: Roles of land: How does the variability invegetation and permafrost have effects on
carbon flux and the geochemical cycle?
How does the variability in snow cover andvegetation have effects on energy and
Figure 17: The interactions among the spheres: i.e., thewater balances at large scales?
atmosphere, the ocean, land and the upper atmosphere. The
Q4:
Roles
of the polar upper atmosphere: What
mesosphere is the layer defined to be part of the upper
effects does the upper atmosphere in theatmosphere and immediately above the stratosphere.

In this theme, we discuss the interactions between the
Arctic region and global-scale processes recognized byclimate system research. In comparison with previous
interests, greater attention is now given to Arctic-global
interactions, exploring the potential significant effect of
atmospheric and ocean circulations in the Arctic on theother regions. One of the examples actively discussed
considers the impact of the sea ice decrease on the East
Asian monsoon in winter, which may contribute to theimprovement of seasonal prediction of abnormal weather.
There are many suggestions from various points of viewthat the Arctic-global interactions may need to be
explored well to facilitate our understanding of climatechange over the time scale of several years to several tensof years, including global warming.
The elements composing the climate system aredescribed first: i.e., the Arctic-global interactions in eachof the tropospheric and stratospheric atmosphere, theocean, land and the upper atmosphere. The central
research of the troposphere and stratosphere covers
dynamical processes of various teleconnection patterns
related to the westerlies and polar vortex surrounding theArctic, and also in the climate variability mode such as
Pacific Decadal Oscillation. The results of these studies
will give a basic understanding on the interactions
between the atmosphere and the other systems (ocean,land and upper atmosphere), and also on the climatechange expected to occur in this century.
The important research topics in the oceanographic
field include water exchange between the Atlantic and thePacific, deep water formation and the general circulationin the mid-latitudes, all of which require the arrangementof observational infrastructures such as a research vessel
and high-resolution numerical models with model
verification. In the terrestrial field, considerable attention
has been paid to quantitative estimates of the effects ofsnow cover variability on energy and water balances over45

polar region have on the lower atmosphere and thewhole region of the upper atmosphere?

Q5: Interactions among multiple spheres: Which one is
the most influential on Arctic-global interactions,among the upper atmosphere, the atmosphere,
snow and vegetation on land, or the ocean?

Introduction
In this theme, we discuss the interactions between the
Arctic and other areas of the planet. In the field of climate
variability and earth system science, significant attention
has been paid to the effects of this topical area on the entire
earth, for example through phenomena such as the El Niño
Southern Oscillation (ENSO) and La Niña. However, as
sea ice declines and as the Arctic environment has beenchanging rapidly in recent years, growing attention has
been paid to the role of a cold source in the Arctic, and toits effects on mid- and low-latitude areas. In fact, several
new research results have been published, mostly byresearch groups in Japan, on the interactions occurring
between the Arctic and other areas in the atmosphere andother spheres; for example, sea ice reduction in the Arctic

produces effects on the winter East Asian monsoon
through atmospheric circulation. This type of research
provides insights into extreme weather and climate
variability, not only creating academic interest but also
addressing social concerns; hence, there is expected to befurther progress in this regard. In the following, theinteractions between the Arctic and the entire earth are
discussed with reference to the atmosphere (including theupper atmosphere), ocean, and land, through scientificquestions, Q1–4, and their answers. Finally, in Q5,
interactions, including between multiple spheres, arediscussed. We hope the discussion here can help guideresearch by providing an overview of Arctic-global
interactions.

Q1: <Roles of the atmosphere> Is its variability intensified or weakened for example, theArctic Oscillation?
The dynamic effects of Arctic sea ice decline in the
Barents Sea and in other seas on the winter East Asianmonsoon and other atmospheric circulation patterns haveattracted attention but are not yet well understood. The
following are important topics. Sea ice decline has
resulted in thermal condition changes near the sea surface,with horizontal scales relatively narrower thanatmospheric circulation. Westerly winds are very weak in
the lower troposphere of the polar and cold regions. Even
though these conditions are not favorable for Rossby wave
responses, why does sea ice decline produce large-scaleatmospheric circulation? We still do not have an answer tothis point. In addition, some basic aspects, such as
potential vorticity distribution in the lower troposphere,
have not been examined sufficiently, implying thepossibility that our understanding does not account for the
dynamic effects of sea ice on the atmosphere. Anothercrucial research topic is the change in effects of sea ice
decline on atmospheric circulation variability (such as
severe winters around Japan); we also need to understandhow a change will proceed, if it does occur. A further
attractive topic focuses on the extent to which atmosphericcirculation in the Arctic affects extremely cold events innorthern Eurasia, as well as its influence on severe 2014
winter in North America.
In addition to the effects of sea ice described above, weshould pay more attention to, and can expect progress inresearch on, the effects of land surface change on
atmospheric circulation. Topics include the effects ofsnow cover decrease in recent years and the future ofclimate in the Arctic and in low- and mid-latitude areas,
as well as frequencies of heat waves and blocking highpressure.
We need to extend research on dynamic interactions
between the troposphere and stratosphere. In research on
the effects of the troposphere on the latter (not limited to
the vertical propagation of Rossby waves), it is becoming
clear that atmospheric circulation variability withequivalent barotropic structures also affects verticalpropagation, even if this research is still in its infancy. One

a. Importance and the present status of the research
A teleconnection pattern (or “teleconnections”) denotes
particular patterns in atmospheric circulation variability at
global scale and could be interpreted as variable modes inwesterly and polar vortices around the Arctic. Various
teleconnections have been reported, as described here,with these having close relationships with the occurrenceof extreme weather. It has also been pointed out by someresearchers that teleconnections play an important role ingenerating climate change over longer time scales ofseveral years to several decades, given their close
relationship with climate variability modes according tosome researchers. For the past 15 years or so, greatest
attention has been paid to the Arctic Oscillation (AO) or
Northern Annular Mode (NAM). In addition, the North
Atlantic Oscillation (NAO), the Pacific-North American
pattern (PNA), and the Western Pacific pattern (WP) areoften explored in connection with extreme weather andclimate variability. Along the same lines, an emerging
state-of-the-art research topic is dynamic connection (orcoupling) between the troposphere and the stratosphere. It
is quite revolutionary to state that the stratosphere isaffected by the troposphere, while the reverse process isalso considered to be important. In addition, research
efforts are exploring how sea ice decline and snow coverchanges produce atmospheric variability, such as in the
East Asian monsoon in winter.
b. Future research
Patterns or climate variability modes (such as AO and
WP), most of which have not yet been understood, haveto be explained for more advanced understanding of
atmospheric circulation characteristics and improved
predictability. For example, we have no answer to thefundamental problem of the relationship with ocean
temperature variability in tropical regions. In addition tothese teleconnections, process studies are also important,such as those relating to the “Arctic cyclone”, Beaufort
high pressure in summer, storm tracks over the Arctic
Ocean, and sudden stratospheric warming frequency.
46

mesosphere and above it. Gravity waves play a central
role in consideration of the mesosphere, and we need toresearch their activities and feedback between waves andmean states.
Researchers in Japan have made significant
contributions to research on the effects of sea ice covervariability in the Arctic Ocean on atmospheric circulation
variability. As in this case regarding the role of thetroposphere-stratosphere in interactions between the
Arctic and the entire earth, research results prepared bygroups in Japan are the focus of attention from others. The
research community in Japan is therefore expected to playa major role in Arctic research.

of the key aspects for dynamic interactions is “modulationof planetary Rossby waves”, which may become
important not only in Arctic research but also in
considering the effects of ENSO on mid- and high-latitude
areas, and intra-seasonal shifts in these effects (Fereday etal., 2008; Ineson and Scaife, 2009). On the other hand, it
is important to also clarify the effects of the stratosphereon the troposphere. As the basis for this objective,
clarification of Lagrangian flows in atmosphericcirculation seems to be crucial, requiring theoreticaladvancement and model development so that flows may
be described. In addition, we should extend researchtargets upwards beyond the stratosphere to theQ2: <Roles of the ocean> Is the water exchange between the Atlantic and the Pacificintensified? Is the deep water formation reduced? Is general circulation modified in the midlatitudes?
the Arctic Ocean flows out to the Atlantic, the NADW
decreases in salinity, and its formation rate decreases in
the Greenland Sea. This change occurs over a long timescale, as it has been detected in the Atlantic (Dickson etal., 2002) and is expected to spread gradually to the global
ocean.
Let us consider the lower layer. The Norwegian Sea
Deep Water, with its origin in the NADW, flows throughthe Fram Strait to the lower layer of the Nansen Basin andthen to the Amundsen Basin, and controls water properties
in the Arctic Ocean lower layer. However, based ongeochemical tracer data, it has been suggested that thislower layer water receives the effects of the Pacific Water
along with the Atlantic Water in the Arctic Ocean middle
layer. The water mass flowing out from the Arctic Ocean
lower layer is called the Upper Arctic Deep Water andreplaces the Norwegian Sea Deep Water.
As global warming continues, sea ice and less saline
water flow out of the Arctic Ocean, and the Greenland ice
sheet melts faster; hence, the NADW becomes less saline,with less penetration to the deep layer. The NADW has
been less saline for half a century, and if this trend
continues, the overflow in the lower layer from thea. Importance and the present status of the research
In interactions via the ocean between the Arctic and theentire earth, main components are the formation andcirculation of North Atlantic Deep Water (NADW), and
the Pacific-to-Atlantic route under mixing with various
water masses in the Arctic Ocean. Furthermore, the ocean
is not only influenced significantly by the atmosphere but
must also provide feedback to the atmosphere through thesea surface. We discuss these factors, including a future
hypothesis and a proposed research strategy.
(1) NADW formation in the Greenland Sea
Figure 18 schematically shows Arctic Ocean
circulation. The circulation is described in the surface (0–200 m depth) and middle (200–700 m depth) layers as
follows: low-salinity Pacific-origin water, including riverwater, stays near the sea surface in the Arctic surface
mixed layer and beneath it. Circulation is driven mainlyby the density distribution composed of surface water andhigh-salinity water in the middle layer, which flows infrom the North Atlantic Ocean. This ocean circulation andwind-driven advection are the main elements determining
sea ice distribution. Once the larger water mass formed in

Figure 18: Ocean circulation in the Arctic Ocean on the vertical cross-section from the Bering
Strait to the Fram Strait. The total ocean depth is about 4000m, and the Atlantic Water flow in
red occupies the depth of 300~700m. The solid lines denote clear currents, and the dottedlines denote mixture of weak currents and mixing. The dotted lines have not been clarified
well yet.

47

atmospheric variations (AO, PDO, PNA, etc.) overperiods of several years to several decades as global
warming proceeds. For example, some model predictions
show that the AO will shift to positive, with a more intensepolar vortex over the Arctic Ocean, and with a mild winterin the mid-latitudes, whereas analysis of observation data
often indicates more frequent negative cases of the AO in
the 21st century. In the case of phenomena with large
natural fluctuations like the AO, we need to consider thesecarefully, combining modeling and observation data. We
should keep in mind the possibility that ocean circulation
varies in response to atmospheric circulation variations
and carries seawater from the mid-latitude and subarctic
areas to the Arctic Ocean.
Common features shown in global warming modelinter-comparison are an atmospheric pressure fall over the
Bering Sea and a rise in the Atlantic subpolar region
during the second half of the 21st century (Chapman andWalsh, 2007). The fall over the Bering Sea leads to item
(2) here. In the Atlantic, sea surface temperature lags
behind the land surface, pushing air pressure up over theocean. As a result, it is predicted that transport will
increase in the Gulf Stream, and high temperature sea
water will extend northward. However, if the atmospherewarms up significantly over the Arctic Ocean, an increasein Atlantic Water may not make a significant difference inthe thermal effects of flow into the Arctic. High salinity
Atlantic Water will approach the Fram Strait, maintaining
the hypothesis that the salinity contrast will control waterexchange between the Atlantic and the Arctic Ocean. Thishypothesis provides insights into the research strategy.

Greenland Sea to the Arctic Ocean will reduce in salinity
and weaken (blue flow in Figure 18). It is then presumed
that the flow from the Canada Basin to the Makarov Basinwill become weaker (yellow line in Figure 18), with adirect effect, through an additional component toward theArctic, on the middle and surface layers above it. Atlantic
Water flowing into the middle layer (red line in Figure 18)
and Pacific Water flowing into the upper layer (green line
in Figure 18) tend to persist longer in the Arctic Ocean andcould modify its density distribution and circulation. Oneof the hypotheses at decadal scale would be a more intense
density contrast in upper and middle layers, intensifying
Arctic-Atlantic water exchanges in upper and middle
layers, and reducing the role of the lower layer in waterexchange. Consequently, heat storage in the Arctic Oceancaused by Atlantic Water increases, mixing partly with thelower layer but also with the upper layer. As a result, theextent of sea ice might reduce; this encourages us toquantify its effects. As for global results, the NADW
becomes less saline in the global ocean conveyor belt,
intensifying mixing with water masses of southward flowin the Atlantic lying above it. It will hence be moredifficult to identify characteristic water properties of theconveyor belt.
(2) Sea water passage from the Pacific to the Atlantic
The Bering Strait has a width of only 85 km, andpermits the inflow of Pacific Water into the Arctic Ocean
at an average flux rate of 0.8 Sv (1 Sv = 106 m3 s−1),
about 3% of the Kuroshio transport, although it plays animportant role in the climate system of the Arctic and theAtlantic. For example, it has been suggested that theDansgaard-Oeschger cycle, representing rapid climatechange during the last glacial period, occurred inassociation with the closure of a freshwater flux from the
Pacific to the Arctic (Hu et al., 2012). Another reportargues that the heat content in Pacific Water may be a main
mechanism for the extreme decline in sea ice in the Pacificsector of the Arctic Ocean.
Pacific Water inflow has long-period variations caused
by a dynamic sea surface height difference between the
Pacific Ocean-Bering Sea and the Arctic Ocean-Atlantic
Ocean (Steele and Ermold, 2007); this also results fromshort-period variations caused by a geostrophic
adjustment to wind stress along the coastline in the Bering
Strait. With regard to mechanisms of dynamic heightvariations, we list freshwater inflow to the North Atlantic
due to the Greenland ice sheet melting and sea ice fluxes,
freshwater storage variations in the individual oceans due
to precipitation minus evaporation, heat storage variationsin the oceans, and atmospheric circulation variations.
Global warming retains both mechanisms, to increase anddecrease inflow from the Pacific, and we hence need topursue research projects of multi-disciplinary observationand modeling to comprehensively cover the atmosphere,sea ice, ocean, and land surface.

b. Future research
In contrast to the hypotheses based on principles andprediction models discussed above, some different
hypotheses may also be proposed; for example, Arctic
Ocean circulation will change to temperature-driven
circulation, under rapid water temperature rise.
Considering that modeling research may advance not only
by elaboration but also by verification of a hypothesis, weshould boldly advance a new topic by keeping an
objective view. When examining differences in responses
to global warming between ocean and land, we need to use
earth system models that appropriately represent theatmosphere and ocean, as well as vegetation and snow
cover on land.
A research vessel is essential for monitoring circulation
and water mass through field observations, even though
we have never yet operated a research icebreaker in Japan.
This barrier should be overcome. In addition, our pressing
need is development of automatic lifting current meters
and automatic driving water samplers. Furthermore, weneed to use geochemical tracers for monitoring long-term
variability.
With reference to circulation between the Arctic andAtlantic Oceans, with their middle and deep layers
strongly affected by bottom topography, we require a
research plan to develop and verify a high-resolution
model. For model verification, we need analyses with abasis in the theory of underlying physical oceanography(for example, relating to vertical mode expansion ofvelocity profiles in a stratified ocean). The key element isverification using data.

(3) Feedback to the Arctic through the atmosphericand ocean general circulations in the mid-latitudes
We note atmospheric circulation changes in thenorthern hemisphere and also feedback produced by theireffects on ocean general circulation in the mid-latitudes.
Several different views have been presented on changes in48

Q3: <Roles of the land> How does the variability in vegetation and permafrost have effects
on carbon flux and the geochemical cycle? How does the variability in snow cover andvegetation have effects on energy and water balances at large scales?
yet sufficient. In addition, it has been reported that
infrared radiation from plants modifies the radiation
balance in the vicinity and that spatial variability in snow
depth is produced by snow drift formation and melting byplants (e.g., Liston (2004)). As vegetation varies, the dragcoefficient varies, with effects on atmospheric circulation.
There has not been significant study of these effects ofboreal forests on atmospheric variability modes in midand high-latitudes. With regard to latent and sensible heat
fluxes within a stable boundary layer on the ground in cold
regions, international research efforts have just started
exploring relevant mechanisms, using field observations
and numerical modeling; i.e., these efforts are expected to
produce new results. The interactions between vegetationand the atmosphere should be explored from both
perspectives, i.e., the effects of vegetation on atmosphericcirculation, and the effects of cloud and precipitation
changes on vegetation.

The effects of terrestrial processes, which apply tointeractions between the Arctic and the entire earth,appear as changes in the carbon balance and in biogeochemical cycles due to vegetation and soil (including
permafrost); and they also relate to changes in energy andwater balances due to snow cover and vegetation. It isnoted that a bio-geochemical cycle is appropriate to
replace a more general term, a material cycle, in the caseof land processes. These changes produce variations inatmospheric circulation and in energy balances and thewater cycle at large scales (Figure 19), in turn producing
effects on other areas and on mid- and low-latitude regions.
Quantitative explanation of these effects therefore
requires assessment of land surface conditions at large
scales, as well as identification of important processes forlarge-scale variations. However, the high level ofheterogeneity of the land surface creates a bottleneck inapplying the findings of physical parameter variability andinteraction processes from field observations to large
scales. This scale-up procedure should be challenged
using a combination of approaches (Figure 20), suchas (i) a process study at a plot scale (100 m or so)using intensified field observation data with vertical
one-dimensional experiments using precise land
surface process models, (ii) analyses of variations atregional scale using observation networks andsatellite data, along with verification using multiple
models at multi-locations, and (iii) examination ofeffects (including interactions) through sensitivity
experiments using regional and global models.

a. Vegetation(1) Importance and present status of research
Terrestrial vegetation has been attracting attention
as a sink for anthropogenic carbon dioxide, throughits influence on the global carbon balance and biogeochemical cycles via absorption and emission ofcarbon dioxide. In the northern boreal regions, theannual cycle of vegetation activity is so large that it
significantly contributes to seasonal variability ofcarbon dioxide concentrations in the global
atmosphere. Through collection of satellite data tomonitor the distribution of vegetation and variations
in vegetation dynamics at large scale, a trend ofincreasing biomass over several recent decades has
been noted in the Arctic Ocean coastal region of
Alaska (Tape et al., 2000). Some global warming
projections indicate that boreal forests will extend
northward and increase biomass, while carbon
storage, including the soil component, will reach amaximum around 2050, maintaining this amountthereafter. There is thus still large uncertainty withregard to quantitative estimation of this trend and its
spatial distribution. We have not yet even clearly
identified where such sinks exist.
It is well known that changes in vegetation affectenergy and water balances through albedo changes.
In particular, albedo reduction resulting from plantparts being exposed above snow cover can
substantially affect the large-scale energy balance,even if quantitative evaluation of these effects is not

Figure 19: Interactions of the land-surface processes withthe atmosphere

Figure 20: Scale-up of the land-surface processes

492005). Process studies have been carried out for frozen
ground with field observation and process models, as an
ordinary approach. More attention is now being paid tolarge-scale effects on carbon balances and on interactions
with ecosystems (e.g., deeper melting tends to enhanceemission rates of greenhouse gases (GHG), such as carbon
dioxide and methane, and to reduce soil moisture available
for vegetation, depending on topography). If permafrost
melts under global warming and turns into wetland, moremethane could be emitted, with worrying potential for
positive feedback to the global climate. However, changes
in the hydrological environment and in the carbon balance(i.e., emission of carbon dioxide and methane) due topermafrost changes depend on various conditions, such as
physical and chemical properties and soil microbial
environments. There hence remains large uncertainty inquantitative estimates of these effects at large scales.

(2) Future research
Following process studies of vegetation dynamics
through field observation and precise process modeling, it
is now desirable to create observation networks over wide
areas of the Arctic, cooperating with those present in Asia,
Europe, and North America. Since the carbon balance andbio-geochemical cycles have a long response time becauseof long time-scale variability in structures and vegetation
species, we need to construct long-term observation
systems and networks to understand the roles of Arctic
vegetation on global climate change (e.g., LTER - Long
Term Ecological Research). By using the outcome of theseprocess studies to clarify the effects of vegetation on the
carbon balance and on bio-geochemical cycles over awide area, we can extract and standardize processes forwide area assessment, validating them over this area withsatellite data, and evaluating the effects of interactions
using earth system models.
With regard to albedo effects on vegetation, it would be
useful to quantify the dependence of albedo oninteractions between vegetation and snow cover, using
satellite data of global distribution of vegetation and land
surface albedo accumulated over the last few decades. To
explore the dynamic effects of vegetation on friction near
the land surface and turbulence structures, we need to
conduct fundamental research on the mechanisms of astable boundary layer and of latent and sensible heat
fluxes on the land surface. One useful method is Large
Eddy Simulation, in which turbulence-induced transport
is calculated directly (Beare et al., 2006).

(2) Future research
To quantify the climate effects of snow cover andfrozen ground at large scales, a core activity involves
extending our understanding of processes at plot scale tobehaviors at large scales. Satellite data are useful for
capturing snow cover area, along with some estimates ofgrain sizes and wetness from microwave data. However,quantitative verification is necessary to reliably estimate
snow properties, such as snow type, depth, and waterequivalent amounts, which are important to quantify theprocesses of snow variations. Soil moisture near the
ground surface is key for terrestrial hydrology processes,
and it would be useful to capture its large-scale
distribution and variability. There have been many efforts
to estimate soil moisture from microwave data, eventhough quantitative reliability still has to be improved (forexample, by removing vegetation effects). A usefulapproach would be to carry out field observation over awide area so that we may verify satellite data for physicalsnow properties (such as grain size and depth), and soil
moisture. We will then be able to improve the reliabilityof satellite data and to elucidate large-scale characteristics
and mechanisms of snow cover and surface soil moisture.
Variations in frozen ground and in the associatedhydrological environment and GHG emission rate aresensitive to local ground surface conditions (such as
vegetation and micro-topography, as well soil properties,
moisture, ice wedge, and micro-organisms). Since soil
conditions have high heterogeneity and are affected byvegetation, it is difficult to capture a large-scale overview
of frozen soil with satellite data, except to estimate thefrozen portion at the ground surface. Soil is also one of the
major sources of uncertainty in the carbon balance, and it
is challenging to compare bottom-up estimates derived
through field observations with top-down estimates fromatmospheric GHG variations. Various approaches arenecessary to understand the effects of soil and frozen
ground on the carbon balance and the hydrologicalenvironment; these include process studies, understandingof large-scale variations (including establishment ofevaluation methods), and quantitative evaluation of
uncertainty through sensitivity experiments, using models.

b. Snow cover and permafrost(1) Importance and present status of research
It has been shown by many studies that snow coverplays a central role in Arctic amplification of global
warming through snow-albedo feedback, in addition tohaving effects on energy and water cycles in mid- andhigh-latitude areas, such as on monsoon systems (e.g.,
Groisman and Davies (2001)). Elucidation of snow coverprocesses has been achieved by field observation andprocess modeling, as in the case of vegetation. In addition,
it is possible to capture long-term variations (including
annual cycles) at large scales using accumulated satellite
data (Brown et al., 2010); where the latter are also usedfor verification of global climate models. It is well known
that snow albedo, which is the key parameter for climate
impacts of snow cover, is affected by snow characteristics(such as snow grain size); and additional effects are also
now attracting attention (for example, concentrations of
impurities in snow cover, namely black carbon (BC), soil
particles, and snow-ice microbes). These effects are now
being explored by process studies based oncomprehensive field observation of snow, radiation,energy, and water balances, along with quantitative
estimates of land surface albedo at large scales using
satellite data.
It is well known that snow cover has a large thermal
insulation effect and reduces vertical heat fluxes. In recent
studies, it has been suggested that the effect of snow
insulation is such so as to lead to a slower increase inpermafrost in winter under deeper snow cover, withdeeper melting within the active layer in summer (Zhang,50

Q4: <Roles of the polar upper atmosphere> What effects does the upper atmosphere in thepolar region have on the lower atmosphere and the whole region of the upper atmosphere?
analysis of cooling in the upper atmosphere will lead us tounderstand warming in the lower atmosphere. It is
desirable to examine upper atmospheric variability overmedium and long ranges, on the basis of its role as a mirrorof the lower atmospheric environment, even though notenough data have been accumulated for accurate estimatesof medium and long-term variability. We have also noted
another issue, namely discrepancies in estimates ofsecular variations in upper atmospheric density between
satellite orbit data and GCM simulations.

a. The upper atmosphere variations in the mid- andlow-latitudes due to energy injection into the polar
region(1) Importance and the present status of the research
Energy enters into the polar upper atmosphere due toparticle precipitation and electromagnetic processes fromnear Earth space, or from the magnetosphere inassociation with aurora phenomena. In particular, it is wellknown that global thermospheric circulation andatmospheric waves are intensified or generated by strong
Joule heating, which is caused by enhancements of theelectric field and conductivity during periods of magnetic
storms. Thus, energy input into the polar region is one of
the causes generating upper atmospheric variations in
mid- and low-latitudes. We are not yet able toquantitatively understand and forecast ionosphericvariations.

(2) Future research
We need to re-examine historical data, such asreanalysis of satellite orbit data, and to perform calibrationof the data set. It would be useful to capture faint signalsof upper atmosphere cooling by improving the accuraciesof observations and model simulations. It will be
indispensable to maintain and further expand
uninterrupted observations over a long period. Please refer
to Q5 in Theme 10.

(2) Future research
It is necessary to quantitatively evaluate the effects ofthe polar upper atmosphere on changes in the global upper
atmosphere, by setting up a wide-area observation
network and performing GCM simulations. As the world
research community is making progress in multiplesatellite observations of the upper atmosphere, we should
also adopt the same strategy in Japan. Please refer to Q4
in Theme 10.

c. The effects of the upper atmosphere on the lower
atmosphere(1) Importance and present status of research
It is well known that nitric oxide (NO) is produced in
the polar lower thermosphere and mesosphere inassociation with auroral phenomena and solar proton
events. NO is transported downward and also towards theequator by eddy diffusion and thermospheric circulation.
The transported NO causes ozone depletion in the upper
stratosphere, although we do not yet have quantitative
understanding of this (e.g., at which altitude it occurs andthe extent to which it causes ozone depletion). The
location of ozone decrease has not yet been properly
estimated.

b. Cooling in the upper atmosphere due to greenhousegas increases(1) Importance and present status of research
The mysterious noctilucent cloud has been noted in thepolar mesosphere in summer since the Industrial
Revolution. This cloud is considered to be a typicalexample of anthropogenic influences that appear in theupper atmosphere in the polar region.
We can recognize ongoing cooling in the upper
atmosphere in response to global lower atmospherewarming due to an increase in carbon dioxide; thisrecognition comes from estimates of secular variations inupper thermosphere density using satellite orbit data, from
more frequent noctilucent cloud observations in high andeven in mid-latitudes, and also from some numericalsimulations. It is not so simple to separate the global
warming trend from other air temperature increases in thelower atmosphere, within which various fluctuation
phenomena exist. Since atmospheric variations generated
in the lower atmosphere propagate to the upper
atmosphere with increasing amplitude, quantitative(2) Future research
It would be useful to quantitatively estimate the effects
of NO, which is produced in association with auroral
phenomena and solar proton events in the lower
atmosphere, through simultaneous observations from thestratosphere to the thermosphere, and GCM simulations.
To support this approach, we need to construct a groundbased global observation network and to observe minor
constituents and dynamics in the upper atmosphere fromsatellites. An additional plan is to develop a precise
photochemical model, which can be included in the upper
atmosphere GCM, or which can be used in collaboration
with numerical simulations. Please refer to Q3 of Theme 10.

Q5: <Interactions among multiple spheres> Which one is the most influential on Arcticglobal interactions, among the upper atmosphere, the atmosphere, snow and vegetation onland, or the ocean?
processes.

In this section, we attempt to propose research
directions for interactions across multiple spheres, namely
the upper atmosphere, the mesosphere, the lower
atmosphere (stratosphere and troposphere), the terrestrial
area, and ocean-sea ice. In addition, we also pay attention
to feedback mechanisms between the Arctic and otherareas of the globe, the energy balance, and water transporta. Introduction: research topics to be proposed
Interactions between the troposphere and other spheres
are important for understanding multiple sphereinteractions, because the troposphere strongly interacts
with the ocean, sea ice, and land on the lower boundary,51

c. Interactions between the atmosphere and land on
the lower boundary
Vegetation, snow cover, and permafrost interact witheach other and vary on land, affecting climate variability
over a wide area, through energy, water, and material
exchanges between the ground surface and the atmosphere.
Process elucidation of vegetation, snow cover, andpermafrost has been carried out steadily on the basis offield observations and detailed process-oriented models.
Quantitative estimates of variability over a wide area
represent a step forward in efforts to assess impacts ofglobal climate variability. Satellite data have been
accumulated relating to certain physical quantities, suchas vegetation distribution and snow-covered portions, andthese have been used for quantitative estimates of widearea variability. On the other hand, there is need for basic
research into some physical parameters, such as soil
moisture and ground conditions; there is also a related
need for development of methods suitable for wide-area
estimates. In principle, scaling up the roles of individual
processes is necessary to acquire quantitative estimatesover a wide area.

and its circulation is also closely linked with thestratosphere and mesosphere through the upper boundary(Figure 17). The troposphere thus has more partners thanother components. It is also true that some spheres interact
with each other without the troposphere and havesignificant influence on the earth system (e.g., ocean
circulation and terrestrial hydrological cycles). These
questions have posed challenges in recent years andindicate various potential research topics, such as the ones
introduced in Questions 1–4. Elucidation of those topics
will deepen the understanding of variations in the climate
system over time scales ranging from intra-seasonal toseveral years and decades, also contributing to improved
accuracy of seasonal forecasts. These topics are
considered to constitute important research challenges.
In recent studies, the effects of the lower boundary on
the troposphere have attracted attention as a potential new
research direction, as represented by atmosphericcirculation variations induced by sea ice decline (refer to
Q1 in Theme 5). This direction needs to be tackled fromnow on. In addition, by combining the opposite direction
from the troposphere to the ocean and sea ice on the lower
boundary (refer to Q2), we should come closer todescribing interaction systems, such as between ocean-sea
ice-atmosphere, and between land surface-atmosphere.

d. The interactions among the troposphere, thestratosphere, the mesosphere and the thermosphere
Research has just commenced on the dynamic couplingof the troposphere-stratosphere, and also on interactions
between the mesosphere-thermosphere and the lower
atmosphere. Important research topics to be pursued
include coupling between the troposphere and thestratosphere, the activities of both Rossby waves andgravity waves along with their impacts on the basic state(refer to Q1), and also accurate estimates of the transportof atmospheric trace components (refer to Q4). As more
results have emerged through observation data and GCM
simulations of variability in the mesosphere-thermosphere
due to stratospheric sudden warming, future advancement
is expected regarding the physical mechanisms thatgenerate vertically coupled variability through thestratosphere-mesosphere-thermosphere.

b. Interactions between the atmosphere and the oceansea ice on the lower boundary
An interesting research topic is elucidation of theprocess in the atmosphere that interacts with lower
boundary components over an intra-seasonal time scale,
contributing to improved accuracy of seasonal forecasts.
In recent studies, much attention has been paid to therelationship between sea ice decline in the Barents Sea andthe East Asian monsoon in winter (refer to Q1 of Theme5). However, there are open questions about which is the
key process of importance, whether a storm track (Inoueet al., 2012) or a stationary Rossby wave response,
generating wavy westerlies (Honda et al., 2009). Studiesof the effects of sea ice on the atmosphere in other regions
have just commenced. It is desirable to also advanceresearch about the effects on the atmosphere resulting
from sea surface temperature anomalies in the ocean, andfrom snow cover distribution in terrestrial areas.
We consider climate variations over time scales ofseveral years to decades to be an important research topic,
because these have to be clarified for future projection of
global warming. Interactions between the atmosphere andlower components (the ocean and land) play key roles inmost of these climate variability modes, such as AO, NAO,
PNA, PDO, and Atlantic Multi-decadal Oscillation(AMO), and constitute interesting research targets. Thesevariations need to be understood in terms of interactions
with ocean and land to elucidate whether these constitutenatural variability or anthropogenic consequences. In
particular, oscillatory variations should be reasonably
reproduced in climate models, with verification against
observation data; then, we could comfortably provide
projections of future trends.
We should also study climate changes over longer timescales, including several decades and more, as relevant toglobal warming. More attention will be paid to ocean
circulation variability induced by atmospheric variability,
and also the reverse relationship (e.g., Chapman andWalsh (2007) cited for Q2)).

e. The role of water and material circulation associatedwith ocean outflows of land-origin substances
In addition to interactions between the atmosphere andother components, land-ocean interactions are also
important foci of study, without the atmosphere. A
concrete topic is explanation of the role of water andmaterial circulation (mostly bio-geochemical cycles)
caused by outflows to the ocean having their origin in land
substances. These substances included in river flows havesignificant impacts on marine biological production, as
described in Themes 3 and 9. Nutrients, as well as metalelements, are significant. In an ocean having enoughnutrients but insufficient iron (such as the subpolar area of
the North Pacific), even a small amount of iron moving
through a river or the atmosphere serves to activate themarine ecosystem. Dissolved iron stays on land, with its
form dependent on the hydrologic cycle and vegetation.
Since a substantial quantity of dissolved organic matterforms complexes with iron in forests and surrounding
rivers, a large amount of dissolved iron flows in rivers andis used by phytoplankton in the ocean. On the other hand,
as a result of either the natural environment or humandevelopment, the iron which remains in a region without
forests settles immediately as granular iron in the oceanand hence, is not utilized in the ecosystem. If precipitation52

decreases in mid-latitude areas due to climate change, ironcompounds may change their forms, affecting the marine
ecosystem.
f. Freshwater balance in the area affecting the Arctic
In Theme 4, the hydrological cycle is described withreference to the freshwater balance in the Arctic Ocean. In
Theme 2, the coupled ice-ocean system in the surface
layer of the Arctic Ocean is explained in detail. In Theme1, along with the main focus on energy transport in the
Arctic area, the associated hydrological cycle is also
shown. In this theme, in conjunction with these efforts, weconcentrate our efforts on exploring vapor transport in thehigh-latitude atmosphere so that we may estimate net
precipitation (equal to gross precipitation minus
evaporation) in the basin of the Arctic rivers. Thus, we
also aim to elucidate freshwater fluxes between the Arctic
Ocean and two other oceans, the Pacific and the Atlantic.
Looking at areas connected to the Arctic, we examine net
precipitation over the North Pacific and North Atlantic, incomparison with vapor transport in the atmosphere. In
approaching these topics, we pay attention to inter-annual
variations in atmospheric circulation patterns, with a basis
in the outcomes for Q1. In association with examining andelucidating salt transport, including in subpolarsubtropical areas in the Pacific and Atlantic, we focus onmechanisms of the global ocean conveyor belt.
g. Research direction for this theme
Based on the above-mentioned discussion, we propose
the following research strategy. A main framework is to
explore fundamental behaviors of multi-sphereinteractions, such as the coupled atmosphere-oceansystem and the coupled atmosphere-terrestrial system. It
would be difficult, without such exploration, to pursue
quantification of meridional heat-water transport. Some
projects, such as AOMIP, are capable of playing a majorrole in elucidation of these topics. Earth system models
also play an important part, with individual element
models verified against data, and with errors appropriately
estimated using data assimilation methods. An important
plan is to examine the effects of material circulation,
which is influenced by atmospheric variability patterns,
the hydrologic cycle as affected by the atmosphere, andeven vegetation distribution, by including thesecomponents in earth system models.

53

Theme 6: Predicting future
Paleoenvironmental records

environmental

Abstract

conditions

of

the

ArcticbasedonArctic Ocean, especially in terms of sea-ice andbiological productivity?
Q4: How different were the terrestrial Arctic
paleoenvironmental conditions from that of today,and how were they related with atmosphericcomposition and climate?
Q5: Were the natural variability on timescales fromyears to centuries in the Arctic different from today?
Research methods include collection and analyses of
ice cores and marine sediment cores as well asgeomorphological and geological surveys of land and seafloor. Regarding the modeling, the approach is to develop
a coupled Earth system model including climate, ice
sheets, vegetation and solid Earth, and to conduct
numerous, long numerical simulations. While it isparticularly important to reconstruct and understandenvironmental conditions during previous warm periods,
it is also important to investigate instability and variabilityof the climate system by studying abrupt climate changes
which occurred repeatedly during glacial periods anddeglaciations, and natural climate variations on timescales
from years to centuries.

The effects and feedbacks resulting from warming of
the Arctic region on ice sheet, sea-ice, permafrost, land
vegetation and aerosols continue to receive attention (seeFigure 21). However, by studying only the modern andrecent past records, it is not possible to understand theentirety of the Arctic climate system which has time scalesof variability over ten thousand years. During the past tensof millions of years, there have been periods when there
were no continental ice sheets and atmospheric CO2
concentrations were much higher than today, and when
there were glacial-interglacial cycles in which Arctic
temperature and ice sheets underwent large variations due
to Earth’s orbital cycles. By examining such records, it ispossible to understand the Arctic climate system and test
numerical models. Here, we list five questions forreconstructing Arctic paleoenvironment and forunderstanding its mechanisms by linking data andnumerical modeling.
Q1: How different are the past Arctic amplifications
from that of today, and what are their causes?
Q2: How did the Greenland and continental ice sheetschange, and what caused them?
Q3: What were the environmental conditions of theIntroduction
The concentration of atmospheric CO2 has varied
significantly through time; for example, it was more than
800 ppm around 55 Ma (Table 1). The Earth’s surface atthe time was warmer than at present due to a stronger
greenhouse effect, a higher sea-surface temperature in the
Arctic Ocean (> 18 ºC) resulting in the growth ofsubtropical ferns. More recently, the CO2 concentration in
the Pliocene was greater than 330 ppm, during a time
when extensive forests of huge trees occupied theCanadian Arctic Archipelago. During the penultimate
interglacial (~125 ka) and the early Holocene (~10 ka),tundra in the Arctic region disappeared and taiga boreal
forests spread around the coasts of the Arctic Ocean coasts
because of the high summer insolation. On the other hand,during the repeated glacial periods, continental ice sheets
grew over vast areas of the Arctic, and the Arctic Ocean
was covered by ice shelf and sea ice. While the changes in
CO2 concentration and insolation are thought to haveaffected the climate globally, the magnitudes of thechanges have been the greatest in the Arctic region.
Today, the Arctic is warming. Sea-ice, permafrost, andtundra vegetation, which are sensitive to temperaturechange, are extensive in the Arctic, and their roles inamplification of climate change have been receiving
attention. In order to clarify these roles, it is important toreconstruct past Arctic environments and understand therelationships between environmental conditions andforcings, such as CO2 concentration and insolation.
The objectives of paleoenvironmental studies are toreconstruct past climates and environments, and to clarify
the mechanisms for changes in them. Researchers haveanalyzed samples from the sea floor, land, and ice sheetswith various methods, assigned their ages, reconstructedenvironmental changes indirectly, and interpreted thegeological records (see Box 1). Furthermore, numericalmodeling (computer simulation) has a growing role inclarificationofclimatechangemechanisms.
Paleoenvironmental studies provide not only knowledge
about past phenomena, but also the means for improving
future predictions through assessment and advancementof climate models. In particular, it is not possible toreconstruct and understand the variations and mechanismsof environmental factors as ice sheets, vegetation, andcarbon cycles, which involve long-term climate changeover tens to thousands of years, only by study of the recent
climate(recent~100
years).
Therefore,
paleoenvironmental studies are important for climaticscience to serve societal needs. Progress in such
paleoenvironmental studies in the Arctic region has
benefitted from Past Global Changes （ PAGES） under theframework of the International Geosphere-Biosphere
Program (IGBP), which was initiated in the 1990’s. In
Japan, large efforts have been made by the PAGES
subcommittee under the Science Council of Japan, since
the establishment of PAGES. Furthermore, Japanesecommunities and individuals have been participating in
numerous international programs involving ice coredrillings, Arctic Ocean drillings, and intercomparison of
paleoclimate models.
Concerning the characteristics of climate change andclimate sensitivity in the Arctic, investigations involving
both paleoclimate data and modeling have beenproceeding, and significant space is used for paleoclimate
studies in the assessment reports of the Intergovernmental
Panel on Climate Change (IPCC). In the past of ten
million years, we can certainly locate many intervals thatare clearly warmer than today, as well as events that canbe utilized to verify climate models. In particular, it isimportant to extend our understanding of the past warm
intervals for advancement of our understanding of Arctic
54

Figure 21: Climate feedbacks and resulting global temperature changes under doubling CO2.
The timescales of each climate component, as well as the relationship between the questions in
the text and climate components, are also shown. [Theme 6]

years. Reconstructions of climate, greenhouse gases, solar
and volcanic activities, as well as paleoclimate modelingon timescales from years to decades, have been conductedon this interval.
However, many tasks remain to be done to achieve
quantitative, spatially dense reconstructions of
paleoenvironments; and to achieve successful
collaborations
betweenpaleoenvironmental
reconstruction and modeling. Five questions of prime
importance for Arctic paleoenvironmental studies follow;
the present status and future tasks related to each one aresummarized.

warming, which may accelerate in the future, and its
effects on the global climate (Table 1). For example, there
have been periods when the concentration of atmospheric
CO2 was higher than today, and no continental ice sheets
existed. There have also been interglacial periods, warmerparts of the glacial-interglacial cycles in which the Arctic
temperature and ice sheets significantly fluctuated.
Furthermore, ice sheet variations and abrupt climatechanges during glacial and deglacial periods are also
important because they may shed light on the future
occurrence of instability in our climate system. There havealso been unusually warm intervals during the past 1,000

Table 1. Targets of the warm intervals in Arctic environmental reconstructions

IntervalAge

CO2concentration(ppm)

Insolation(with respect to today)

Northern Hemispherehigh latitude air temperature(℃ higher than today)

Late Paleocene

55 Ma

800-2000

Equal to or higher

8-35

Pliocene warm period

3.5 Ma330-380

Equal to or higher

11-16

Interglacial

400 ka, 125 ka

270-280

Higher5

Early Holocene

10 ka

270

Higher2

Medieval Warm
Period

1 ka

280

Nearly equal

0-5

55

Q1: How different are the past Arctic amplifications from that of today, and what are thecauses of these differences?
a. Importance of research and present status
When we examine the long-term evolution of climate
during the past several tens of millions years, thefollowing becomes clear. When CO2 concentrations werehigh, air temperature and sea-surface temperatures werealso high, and continental ice sheets emerged andexpanded as CO2 concentration decreased. As theNorthern Hemisphere ice sheets expanded, glacialinterglacial cycles emerged in association with variations
in summer insolation, and their amplitudes have increased.
From available data, it is known that polar amplification
occurred in all cases (Figure 22).

The Integrated Ocean Drilling Program (IODP) Arctic
Coring Expedition (ACEX)36, in which Japan participatedin 2004, obtained paleoclimatic records of the past 55 Ma
from Lomonosov Ridge in the vicinity of the North Pole
(Moran et al., 2006). The analyses of sediments andorganic compounds showed that the average sea-surface
temperature of the Arctic Ocean was 18 ºC at 55 Ma,
around the Paleocene-Eocene boundary, and reached 24ºC when greenhouse gases were released over a shortperiod during the maximum warm interval. At least fiveresearch groups, including a Japanese team, conductedcomparisons between model results and data for the

Figure 22: Data-model comparisons of surface air temperatures (SAT) and sea-surface temperatures (SST) for the Eocene,
Pliocene, and the last glacial maximum (LGM) (Box 5.1, IPCC AR5), Figure: 1 Comparison of data and multi-model mean
(MMM) simulations, for four periods, showing (a) Sea-surface temperature (SST) anomalies, (b) Zonally averaged SST
anomalies, (c) Zonally averaged global (green) and land (grey) surface air temperature (SAT) anomalies, and (d) Land SAT
anomalies. The time periods are 2081–2100 for the Representative Concentration Pathway (RCP) 8.5 (top row), Last Glacial
Maximum (LGM, second row), mid-Pliocene Warm Period (MPWP, third row) and Early Eocene Climatic Optimum (EECO,
bottom row).

36
Climate sensitivity: The temperature changes that only take into account fast feedbacks, such as the changes in clouds and water vapor over the sea
surface, which can be completed within several decades. Normally, the term is used for the changes in global terrestrial mean surface temperature forCO2 doubling.

56

today, which affected the cryosphere, including sea ice.
The climate changes in the Northern Hemisphere during
the past 2,000 years are characterized by the Medieval
Warm Period of ca. 950–1250 AD and the Little Ice Ageof ca. 1450–1850 AD. The changes in the Arctic region
were significantly greater than those of the average
Northern Hemisphere. Major radiative forcings such as
greenhouse gases, solar radiation, and volcanism havebeen reconstructed with high temporal resolution for thelast 2,000 years. It is possible to use those parameters as
input data for transient experiments with generalcirculation models, and an international comparison
project for paleoclimate models, in which Japan
participated, was conducted. While the results of theclimate models fall within the uncertainty range ofreconstructions for Northern Hemisphere mean
temperatures, the agreement between models, or between
climate data and models, is poor when considering theArctic region. In addition, because the uncertainties inradiative forcing and reconstructed data are large in the
Arctic, it is at present difficult to constrain the climate
sensitivity of the region firmly; hence, this remains asignificant task for the future.

following two periods: ca. 50 Ma in the middle Eocene
warm interval, and ca. 3.5 Ma in the middle Pliocene
warm period. The results indicated that models
overestimated air temperatures at low latitudes andunderestimated at high latitudes, compared to the data. In
particular, the discrepancy in the Polar Regions was due
to problems in both data and models. Regarding the data,it has been pointed out that different regression curves
from proxies to sea-surface temperatures must be
employed according to the seasons. On the other hand, it
is necessary to assess the validity of the radiation
processes of clouds in Polar Regions, and of the heattransport processes by the oceans. It is also necessary toassess consistency between the data and models ofterrestrial vegetation.
During the interglacial periods of the glacialinterglacial cycles of the last one million years, Northern
Hemisphere continental ice sheets disappeared (orsignificantly shrunk), except for the Greenland ice sheet.
While the Earth experienced 10–20 m higher sea levels
than today during some of the last five interglacials, CO2concentrations were roughly the same during all theinterglacials (280±10 ppm) and the only difference inradiative forcing was from variation in the distribution of
insolation, due to changes in orbital parameters. For
example, the summer solstice insolation reached amaximum, which was approximately 10% greater thanthat of the maximum of the Holocene, at 126 ka during thethe penultimate interglacial. Recent investigations showed
evidence for high air temperatures, northward forest
expansions, and sea levels 5–10 m higher than today(indicating smaller ice sheets in the Northern Hemisphere).
In addition, evidence exists that the central Arctic Ocean
was only seasonally covered by sea ice, suggesting higher
summer air temperature than today. According to theestimations by the North Greenland Eemian Ice Drilling(NEEM) project, the state of the art international ice sheet
drilling project in which Japan has participated in the icecore drilling and analyses, the mean annual air
temperature in the northwestern Greenland interior was 8ºC higher than today (NEEM project members, 2013).
Concerning the penultimate interglacial, an internationalmodel-data comparison project (Paleoclimate Model
Intercomparison Project, PMIP) was conducted withparticipation of 16 climate models including Japanese
ones (Figure 10.9, IPCC AR5). Transient modelexperiments with time-varying insolation andatmospheric composition were also conducted using
seven models. The results indicated that, while nostatistically significant difference was seen between thedata and models in sea-surface temperatures, statisticallysignificant differences were found in the terrestrial air
temperatures of December-February. This resulted insignificantly lower values of the modeled mean annual air
temperatures of terrestrial high latitudes, compared withreconstructions. The reasons for such discrepancies
between the data and models may be due to insufficient
expression of processes concerning clouds, sea ice, andland vegetation in the models. Another reason may be theneglect of effects from changes in the source-regions ofwater vapor with decreasing sea-ice cover, on thereconstructed air temperatures based on the isotopes of ice cores.
The Arctic region experienced a warm interval early in
the Holocene (current interglacial), except for a part ofNorth America, where continental ice sheets still existed.
This can be attributed to greater summer insolation thanb. Future research
Progress has been made in reconstruction of past air
temperatures and water temperatures by analyses ofsediments and ice cores, as well as on simulations of pastenvironments by climate models. However, these are stillin various stages of development, for example, because oferrors in the processes used to convert proxy data into
temperatures, as well as neglect of the interactions
between ice sheets and climate in the models. Furthermore,while studies about estimating climate sensitivity from
paleoclimate information exist, few studies focused on the
Arctic. In order to quantitatively reconstruct and analyze
the causes of polar amplification and ice-sheet-driven sealevel change, it is necessary to provide collaborativeinteraction between proxy-data collections (e.g.,greenhouse gases, aerosols, ice sheets, sea ice) and theEarth system modeling to simulate paleoenvironments.
Many tasks have been identified through the datamodel comparisons. Data-related tasks involve obtaining
and extensively analyzing samples (Arctic-sea sedimentcores and Greenland ice cores) for intervals that currently
have little data, while considering seasonal and climatic
dependences of the regression curves for converting proxy
data into temperatures. On the other hand, modelingrelated tasks involve investigating elementary processes,
such as radiative processes of polar clouds and aerosols,
heat transport and stratification processes of ocean and sea
ice, as well as the processes involving land vegetation andterrestrial/ice-sheet interfaces. Then, these updated
processes will need to be incorporated in the climate
models. It is necessary to continue improving both data
and models, as well as comparing them for different ages.
For interpreting paleoclimatic data on the relationships
between radiative forcings and climate, it is essential toconsider feedbacks from the cryosphere (e.g., ice sheets)and land vegetation to air temperature. The responses of
ice sheets and land vegetation to warming extend for
centuries to millennia; thus, their influences on Arctic
amplification and global temperature are similarly
prolonged. This type of climate sensitivity (magnitude oftemperature increase for a given increase in CO2
concentration), including long-timescale feedback, is57

well as in boundary conditions). Therefore, it is essential
to reconstruct accurately the boundary conditions, toconduct model experiments involving many different
periods, and to secure resources for the extensive
computations needed. It is necessary, for example, toobtain samples (e.g., ice cores, borehole temperatures,marine sediments, permafrost) representative of extensive
geographic areas and long time-scales, to develop proxies
and analytical methods, to acquire large paleoclimatic
data sets of high resolution, and to interpret the data by
proxy-data assimilation. In order to link the past and thepresent, it is also necessary to accumulate pan-Arctic
paleoenvironmental sample archives covering the years
after 2000 A.D.

called “Earth System Climate Sensitivity (ESCS)” and it
is greater than ordinary “climate sensitivity (86)” which
only considers short-timescale feedback (Figure 21).
According to investigations based on comparison ofclimate models with paleoclimate data, the ESCS can be
up to twice as high as the ordinary climate sensitivity, andcan vary depending on climatic conditions(PALEOSENSE
Project Members, 2012).
To
quantitatively utilize long-term paleoclimate informationin future studies, it is necessary to integrate climate
modeling with whole-Earth-system and paleoclimate
proxies. In particular, assessment of the performance ofthe models requires considerations of all uncertainties(e.g., in parameterizations and structures of models, as

Q2: How did the Greenland and continental ice sheets change, and what caused them?
What are their relationships with, and contributions to, sea level?
inverse modeling using a glacial isostatic adjustment(GIA) model, with relative sea-level data as input (seeTheme 11).
In the Arctic Ocean, there have been times in glacial
periods when continental shelves were exposed due todrops in sea level and then covered by ice sheets. In suchcases, evidence for past ice sheets exist as erosional
furrows caused by icebergs, lined structures caused byglaciers, and depositional topography caused by ice-raftedmatter dropped onto the sea floor of up to 1000-m water
depth. While studies on the Lomonosov Ridge andChukchi Sea have indicated the possibility of ice sheet
expansion from continents to the central Arctic Ocean, as
well as the presence of an ice sheet over the continental
shelf of the East Siberian Sea, the evidence is still
fragmentary. Progress is being made on simulation of the
distribution of past ice sheets by climate-ice sheet models,and on linking them to understanding of the processes
driving ice-sheet fluctuations.

a. Importance of the research and state of the art(1) Mechanisms and prediction of ice-sheet variations
The fluctuation of ice sheets significantly affect the
Earth’s environment by changes in sea level and inatmospheric/oceanic circulation (see Theme 4). The
response of ice sheets to climate change exhibits
hysteresis behavior with different “threshold” values forincreases and decreases in temperature. When such
threshold values are crossed, an ice sheet drasticallychanges its shape or volume. Numerical simulations ofglacial-interglacial cycles have revealed that it isextremely important to elucidate different hysteresis
structures for different ice sheets, in order to estimate theirabrupt decay in response to warming (Abe-Ouchi et al.,2013). Furthermore, because the time scale of ice-sheet
response is very long, there is concern that past climatechanges may influence ice sheets for more than several
hundred years into the future. In fact, members of
SeaRISE, an international project for comparing ice-sheet
models, have pointed out the possibility that considerationof ice-sheet histories over the last 130 ka can generate
differences in the predicted change in ice volume in thenext 100 years, by as much as 40% (Bindschadler et al.,2013).
In order to constrain future changes in ice sheets
accurately, it is important to reduce the uncertainty of icesheet responses to external forcing. One way to achieve
this is to clarify actual ice-sheet changes in the past, andtheir driving factors, thereby advancing their simulation
by ice-sheet models. In particular, it is indispensable toestimate accurately the threshold values of climate andCO2 concentration that cause ice sheets to collapse. To
accomplish this, it is necessary to conduct numericalexperiments, and to acquire data that can lead to better
understanding of the hysteresis structures.

(3) Past Greenland ice sheets
Investigations have been in progress concerning therelationships between the growth of the Greenland Ice
Sheet, which began ca. 3 Ma, and CO2 concentrations; aswell as between the responses of the Northern Hemisphere
ice sheets (North America, western Eurasia, andGreenland) to orbital parameters and CO2 during theglacial-interglacial cycles. In particular, relatively
abundant data are available for reconstructing ice-sheet
volume and distributions, as well as climate conditions,
during the penultimate interglacial at ~125 ka, with 5–10
m higher sea level than today, and the deglacial period
from the last glacial maximum (LGM, 20 ka) to thepresent. Simulations by integrated climate-ice-sheet
models have also been initiated.
According to ice-coring and analytical projects inwhich Japan participated, as well as the analyses of marine
sediment cores collected from the south of Greenland, theair temperature in the LGM at the NEEM site (NE in
Figure 23) was 8±4 ºC higher than today, with frequentsurface melting. However, the estimated reduction of icesheet volume was only equivalent to less than ca. 2 m ofsea level (NEEM community members, 2013). Simulated
Greenland ice sheets show large differences amongmodels (Figure 23), and sufficient data for evaluating
model performance are lacking. On the other hand,
analyses of ice cores suggested that, during the interglacial(2) Reconstruction of the past ice sheet distribution
It is possible to reconstruct the areal bounds of past icesheet expansions by identifying marginal positions andages of the ice sheets from geomorphological andgeological evidence (e.g., glacial erosional morphology),
as well as from traces of past glaciers and ice sheets, lefton land and the sea floor. For interglacials, when ice sheets
were reduced, ice-sheet distribution can be reconstructedbased on relationships between marine sediment cores andterrestrial geological distribution. For reconstructing thevolume of ice sheets, a commonly employed method is58

Figure 23: Distribution of Greenland Ice Sheet during the LGM, computed by state-of-the-art
ice sheet models: IPCC AR5, Figure 5.16, Simulated GIS elevation at the Last Interglacial(LIG) in transient (Q, R, S), and constant-forcing experiments, (B)icesheet models, and by evaluating the results bycomparisons with field data. The important aspects foradvancing the models are (1) interaction between ice
sheets and oceans; (2) basal processes; (3)atmosphere/surface mass balance processes; (4)advancement of interactions between ice sheets and solid
Earth; and (5) increase in the resolution of models.
Furthermore, it is necessary to directly or indirectly
integrates ice sheet models with other models, such as
those pertaining to atmosphere, ocean, GIA, and land
vegetation. A massive amount of computer resources andadequate infrastructure would be required to proceed withmodel experiments fully utilizing paleoclimate data.

of ca. 400 ka, sea level was 10–20 m higher that today.
The Greenland ice sheet had retreated extensively andland vegetation was present despite weak summer
insolation. The model simulations for this period have notbeen successful, and the factors driving the retreat of theice sheet are unclear.
While the Greenland ice sheet extended to cover thecontinental shelves during the LGM, the evidence fromsea floor surveys is limited to a part of southern Greenland,
and the evidence from land is also fragmentary. It issuggested that existing data regarding the paleoshorelineheight during the deglaciation period contain large errors,
and consistent results involving data and models have notyet been obtained.

(2) Reconstruction of ice sheet distribution based onterrestrial geomorphological investigations
Detailed investigations on the correspondence between
marine sediments and land geology during the pastinterglacials are needed at many sites on continental
shelves where ice sheets are thought to have existed(particularly Greenland). It is necessary to reconstruct,both extensively and in detail, the locations of ice sheet
margins, ice-sheet basal environments, and uplifted beachmorphologies by studying the traces of ice-sheet reduction
on land. Recently, discussions have been made about past
ice-sheet fluctuations based on satellite-observed
temporal changes in the gravity field and on GIA
modeling. For such studies, it is important to remove thesignal from modern ice sheet fluctuations. To establish a
GIA model with detailed seawater loading, it isindispensable to incorporate the effects of changes in the
Earth’s rotation on sea level changes, on the viscosity
structure of the interior Earth, and on the close link
between geodetic data and ice-sheet models.
Furthermore, to reconstruct long-term changes in icesheet margins and their retreat processes, it is important tosurvey the sea floor and analyze multi-beam topographic
data obtained by icebreakers over the Siberian continental
shelf and continental slope. In addition, in order to obtain
the age of formation for glacial landforms, it is desirable
to collect marine sediment cores and correlatestratigraphic horizons. These will bring new knowledge ofb. Future research
Following are the leading issues that need to beresolved by linking models and data:
・ Understanding the mechanisms for the growth anddecay of past Greenland ice sheet and thedetermination of their thresholds,
・ Elucidation of the change to dominant 100 ka cyclesof the Northern Hemisphere ice sheets at ca. 1 Ma,
・ Finding out when, and due to what processes, did theice sheets surrounding the Arctic Ocean exist,
・ Finding out why the sea level during the interglacialof 400 ka was very high, and why the Greenland ice
sheet retreated extensively,
・ Achieving detailed model-reproduction of theNorthern Hemisphere and Greenland ice sheets
during glacial cycles and deglacial periods, andestimation of threshold values for the ice sheetchanges, and・ Understanding and reproduction of the determining
mechanisms for the occurrence, cycles andmagnitudes of large-scale, iceberg-releasing events.
(1) Ice sheet-climate model
In order to solve the mystery of past ice sheets, it isnecessary to reproduce their non-stationary responses toexternal forcing (e.g., insolation and greenhouse gases),by numerical simulations with integrated climate and59participation into the future as well.
For precise temperature estimations of ice sheet andatmosphere, it is essential to interpret water-isotope
signals accurately, which in turn requires consideration ofvariations of ice sheets and ice flows. At the same time,
accurate reconstruction of the past ice sheet variations
requires high-quality paleoenvironmental reconstruction,
thus they depend on each other. An important target here
is to find the most consistent reconstructions of both, byemploying a data assimilation technique. For this reason,
it is also desirable to conduct shallow and intermediatedepth drillings at many sites on the Greenland ice sheet,and on circum-Arctic ice caps and glaciers.

the history of Northern Hemisphere ice sheets, which are
currently unknown, and provide valuable data for testing
paleoclimate models.
(3) Ice cores
To clarify the history of the Greenland ice sheet, deep
drillings at selected sites and many shallow drillings overextensive areas, are both necessary. Particularly importantresearch targets include the fast-flowing ice in northeast
Greenland, continuous climate records from thepenultimate interglacial to the present, and the onset ageof ice sheet cover, as determined by analyses of the basal
ice. Because Japan has been participating in international
drilling projects, it is important to continue active

Q3: What were the environmental conditions of the Arctic Ocean, especially in terms of seaice and biological productivity?
IP25), calcite oxygen isotopic ratios, inert gases, andmercury isotopic ratios. Information concerning sea-ice
distribution in the Arctic Ocean, can also be provided byother proxies: coastal marine sediments, fossil driftwood,fossil whalebones, fossil shells, and wave-eroded
topography. Moreover, indirect estimates of the extent of
sea ice have also been conducted based on ice-core andland-vegetation records. As ice cores can be analyzed athigh temporal resolution, various ice-core-based sea-ice
proxies have been proposed (e.g., oxygen isotopic ratios
of ice, sodium ion concentrations, methane sulphonic acidconcentrations, and halogen concentrations).
The Integrated Ocean Drilling Program (IODP) Arctic
Coring Expedition (ACEX) drilled the Arctic sea floor on
the Lomonosov Ridge in 2004 and reported theevolutionary history of the sea-ice record for the past 55
Myr (Figure 24: Moran et al., 2006). Based on theappearance of the IRD, it became evident that theformation of sea-ice began around 47 Ma. Perennial sea-a. State of the art of the research
In order to understand Arctic climate it is important toevaluate sea-ice albedo feedback, and thus, it is necessary
to understand accurately, past sea-ice distributions. Whilescientists have evaluated the effects of past ice-sheet
distributions on the past air circulation of the Northern
Hemisphere using climate models, the effects of sea-ice
have not been well addressed. This stems from the lack ofdetailed understanding of the past distribution of sea ice.
It is therefore necessary to elucidate the sea-surface
conditions that govern both winter and summer
atmospheric circulations, by further refining sea-ice
proxies, and by reconstructing sea-ice margins during
both winter and summer, at many locations.
Reconstructions of past sea-ice distributions have been
tried by employing proxies in marine sediments, such as
ice rafted debris (IRD), grain size distribution, iron oxide
particles, microfossils (diatoms, dinoflagellates, benthic
foraminifers, silicoflagellates), biomarkers (in particular

Figure 24: Changes in benthic foraminiferal oxygen isotopic composition, ice sheet formationin both the Southern and Northern Hemispheres, and sea-ice formation in the Arctic Ocean(Oxygen isotopic data are from Zachos et al., 2001.).

60

for the Norwegian Sea and Canadian Arctic Archipelagopassages, but not for other regions; hence, a sea-ice
distribution map cannot yet be drawn. We need to expand
the records spatially. It is a good idea to select topographic
low areas of marginal seas where sedimentation rates werehigh, to obtain sediment cores, and employ sea-ice proxies
for the reconstruction of past sea-ice distribution.
The early Holocene is the most advanced interval of thefour target-research time-periods. Sea-ice reconstructions
employing dinoflagellate remains have been made insignificantly extensive areas of the Arctic Ocean for that
period (de Vernal et al., 2013). It is desirable to refine seaice reconstructions by employing proxies other thandinoflagellates. While sea-ice reconstructions have been
made in the Norwegian Sea and Atlantic sector of Arctic
Ocean for the LGM; today, it is not possible to compare
different sites because of the lack of systematicinvestigations using common proxies. It would bedesirable to obtain data employing common proxies more
systematically. Furthermore, the number of existing coresis insufficient for fully understanding past distributions.
Thus, we need to target continental-slope regions withhigh sedimentation rates, obtain marine sediment cores,
determine ages, and obtain proxy records. For age
determination, while core-to-core correlation is useful, it
is important to systematically obtain many cores andanalyze them in order to establish stratigraphy for each of
the regions. Regarding the Pliocene, we only haveinformation from the ACEX record, and other Pliocene
records for which sections were coincidentally obtained.
It is important to drill several hundred meters deep andobtain Pliocene sections where such Pliocene records
likely exist: on the Lomonosov and Mendeleev Ridges. It
is desirable to proceed with the drilling as part of the IODP,
but before this can occur, it will be necessary to acquire
topographic and seafloor structural data for the candidate
drill sites, and to obtain preliminary results by analyzing
piston cores.
While a number of sea-ice proxies are already used forpast sea-ice distributions, developing new proxies, as well
as refinement of the current proxies, remains important. It
is warranted to clarify the sea surface conditions thatgovern winter and summer air circulation, byreconstructing winter and summer distributions of sea-ice
margins at many stations.
Ice cores are natural archives recording sea-ice changes
with high temporal resolution, and hence making theeffective use of them in the future, highly desirable. We
need to reinterpret existing proxy records, develop new
proxies and apply them for sea-ice reconstructions. A
possibility of reconstructing biological production using
ice core records has also been pointed out, and progress inresearch on this approach is expected in the future.
The Arctic Ocean of the Pacific sector (e.g., Chuckchi
Sea, East Siberian Sea, Laptev Sea) are regions whereparticle flux increased, due especially to sea-ice decline,
during the 1900s to 2000s. For this reason, the Arctic
Ocean of the Pacific sector constitutes a hotspot where
biological production will likely increase as sea-ice
declines drastically in the future. Studies in this region are
expected to clarify the relationships between past climatesand biological productivity, as well as material balance.
Furthermore, it is extremely indispensable to conduct
numerical simulations for various intervals by employing
the integrated global circlation models (atmosphereocean-sea ice, Theme B). It is also essential to establish

ice was formed 16-13 Ma. The extent of sea-ice increased
with global cooling after 3 Ma in the North Pacific, North
Atlantic, and Norwegian Sea. During the penultimate
interglacial of 125 ka, planktonic foraminifers, whichdwell in seasonal sea-ice areas, appeared in the central
Arctic Ocean. The perennial sea-ice during the early
Holocene is thought to be less than what we see today,
based on the driftwood record of Greenland beaches,fossil bowhead wales on the coasts of the CanadianArchipelago, and IP25 in marine sediments of theNorthwest Passage. On the other hand, sea-ice was shown
to be abundant during the early Holocene in the Chukchi
Sea, based on assemblage components of dinoflagellate
cysts. Hence, it was suggested that expansions and retreatsof sea-ice cover were not uniform within the Arctic Ocean.
The continental shelves of the Okhotsk and Bering Seas,
which represent typical seasonal sea-ice regions, areamong the regions with the world’s greatest biologicalproductivity. During the early to middle Holocene, in the
Okhotsk and Bering Seas, coccolithophores wererelatively abundant, and diatoms became dominant during
the late Holocene. As such changes occurred, theefficiency of biological pump must also have changed
dynamically. However, the factors controlling thesechanges have not yet been clarified.
The IODP ACEX 302 has played a major role inreconstructing sea-ice in the Arctic Ocean. The ACEX
materialized as part of the IODP, which was primarily coled by the US and Japan, and operated by the European
consortium. In 2009, parts of the Bering Sea floor were
drilled by Professor Kozo Takahashi of Kyushu University,and others, as part of the IODP. On the other hand,scientists of the US, Europe, and Japan have submitted
new drilling proposals for the Arctic Ocean. None of thesehas yet been scheduled because of insufficient site
information, the existence of which is a prerequisite fordrilling. While paleoceanographic studies in the Arctic
Ocean have primarily been advanced by the scientists ofEuropean and North American countries thus far, in recent
years the Peoples Republic of China and South Korea
have become active, employing ice breakers to pursue
investigations of sea-floor topography, structural survey,
and piston-coring of sediments. As for our own
investigations in Japan, the R/V Mirai has been employed
for sea-floor topography and sediment surveys during thedecade since the year 2000. Since 2010, surveys
employing the vessel I/B Araon have been carried out asa joint project between the scientists at the Korean Polar
Research Institute and Hokkaido University. In order topursue continuous paleoceanographic studies in the Arctic
Ocean hereafter, it is indispensable for Japan to constructan icebreaker research vessel and make good use of it.
b. Future research
It is an urgent task to reconstruct sea-ice distributions
during intervals warmer than today, in order to predict
future sea-ice distributions in the Arctic Ocean.
Specifically, we need to target the following intervals: theMedieval Warm Period (1 ka), the early Holocene (10 ka),
the penultimate interglacial (125 kya), and the Pliocene(3.5 Ma) (Table 1).
In order to reconstruct past sea-ice distribution, we needto reconstruct the conditions favoring sea-ice formation byobtaining marine sediment cores, and by analyzing themin relation to sea-ice proxies. Regarding the Medieval
Warm Period, the sea-ice conditions are understood only61

and ocean simultaneously, and the achievements thus far
are fragmentary. In order to make good predictive use of
paleoclimate records, vigorous advances in paleoclimate
simulation are required. This can only be achieved bygreatly improving computational resources and related
infrastructure.

agreement
betweenthemodel
resultsandpaleoceanographic data (sea-ice and marine ecologicalsystem), thereby advancing our understanding of theirdetermining processes. Conducting the necessary
experiments for sea-ice and ecological systems requires
vast computing resources. This is due to the need for
detailed calculation of conditions in the both atmosphere

Q4: How different were the terrestrial Arctic paleoenvironmental conditions from those of
today, and how were they related to atmospheric composition and climate?
also been measured in conventional ways, at very highresolution, by continuous melting methods. Japan has
been a leading country in the analyses of aerosols andgases.
In recent years, numerical simulation of terrestrial
paleoenvironments has been carried out with global
climate models involving physical and chemical
feedbacks from changes in the distribution of vegetation.
The results have been compiled by the Palaeoclimate
Modelling Inter-comparison Project (PMIP). An exampleof the model simulation for the LGM is shown in Figure
25. Because the results of modeling cannot be directlycompared with observational results, there are many
regions where the distributions of past vegetation cannot
be well established. In addition, there are other remaining
problems such as “Green Sahara”, which cannot be
reproduced by current climate models (PMIP, Joussaume
et al., 1999). However, the importance of changes in land
vegetation in determining climate has been demonstrated
quantitatively, for example by improving agreement
between model and data averaged over large areas, byintroducing land-vegetation feedback in a model (O’ishi
and Abe-Ouchi, 2011). The terrestrial environments in the
Arctic region must have drastically changed along withthe global paleoclimatic changes such as the glacialinterglacial cycles, due to polar amplification. In order toinvestigate the Earth’s climate, it is extremely importantto accurately reconstruct the terrestrial paleoenvironment
and understand its underlying mechanisms.

a. Importance of the research and state of the art
Past status and changes of land surface conditions, suchas vegetation, may provide essential clues forreconstructing past climatic conditions and for improving
the accuracy of climate models by providing boundary
conditions and validation data. However, the terrestrial
paleoenvironmental records available from the Arctic
region are comparatively few, with respect to those fromtemperate and tropical regions. Except for analytical datafrom some lacustrine sediments, they have been confinedto sporadic pollen records, remains of macro plants,
lacustrine sediments, and fragmentary and qualitative
information from glacial geomorphology. In recent years,
however, possibilities have emerged in paleoenvironmental
reconstructions employing temperature profiles ofpermafrost, isotopic analyses of Yedoma containing ice
and organic matter (see Theme 12), and analyses ofmultiple proxies. While variations of permafrost areconsidered to provide positive feedback for climaticchange, the extent of permafrost, the quantities of its
constituting substances, and their rate of change are notwell understood. This results in substantial uncertainty inclimate-change predictions. Nevertheless, efforts havejust begun in recognizing permafrost layers as archives ofterrestrial environments, and in understanding therelationships between environmental changes related tofrozen ground dynamics and climate change.
Because ice cores contain information on both the
Arctic and global environments, they provide outstanding
records for reconstructing the changes of substancesoriginating from land (e.g., aerosols and greenhousegases), which are important constraints for paleoclimate
reconstruction of the Arctic region. In recent years, it has
become increasingly possible to measure trace species
such as metal isotopes of aerosols, black carbon, andorganic aerosols. Furthermore, it has become possible toanalyze methane and water-soluble aerosols, which haveb. Future research
Regarding the research on reconstructing past land
vegetation by modeling, it is necessary to make progressin verification of not only the equilibrium states of land
vegetation, but also their changes over time. In order toachieve this, it is necessary to conduct long-integration
experiments with variable orbital and volcanic forcings,

Figure 25: Examples of model simulations of the LGM and the present by dynamic land vegetation models (Harrisonand Prentice, 2003). Three panels, starting from the left, show the ground cover types during the LGM, from aJapanese model, a French model and from paleoenvironmental data, respectively. The illustration on the far rightshows the ground cover types of the present climate.

62

(Pollack et al., 2003) are important in regions such as
Siberia where paleoenvironmental data are sparse. It could
also be possible to put constraints on the reconstructionsof past surface temperature based on the depth ofpermafrost. Because most areas in permafrost regions
cannot be accessed without employing helicopters andsnowmachines, extensive logistical support is required forpermafrost drillings and outcrop investigations.
Because the processes for methane formation anddestruction are rather limited, they could be utilized as
constraints on carbon cycles in a model. Improvements insimulations could be expected particularly in the
distributions of swamps and vegetation in high latitudes,
as well as for soil organic carbon, by employing methane
concentrations (measured in ice cores) as constraining
factors. On the other hand, the isotopic ratios of aerosols
can be used as clues to understand provenance andtransport processes. Sulfur isotopic ratios of sulfuric acidaerosols are valuable for provenance estimation becauseof the fact that the isotopic ratios vary depending on, forexample, gypsum, volcanos, and marine biotas, and thatthe isotopic ratios of strontium and neodymium on dust
(silica minerals) vary depending on the provenancecontinents and regions. In recent years, better isotopic data
can be obtained with higher temporal resolution andaccuracy than ever, attributable to improved analyticalmethods. Furthermore, it may be possible in the future toisolate and reconstruct aerosol histories of forest fires, soil
aerosols, biogenic, and anthropogenic activities because
many compounds in organic aerosols have limited
provenances. It is also necessary to make progress in thearea of multiple-proxy analyses, for example, by
combining sulfur ion concentrations and sulfur isotopic
ratios in ice cores, by acquiring the composition andcarbon isotopic ratios of organic matter, and by estimating
emission provenance of gases by isotopic analyses.

using Earth-system models involving not only coupledatmosphere and ocean, but also the cycles and feedback
among elements such as carbon, nitrogen, phosphate andsulphate, which may limit the growth of vegetation.
Among various terrestrial environmental factors, thedistribution of vegetation, soil-water content, and surface
wind speed most affect dust-source strength. It is thus
expected that using dust data from ice cores, marine cores,
and other archives, as constraints on the models should
improve the reproducibility of these factors in climate
modeling (Lambert et al., 2013). While the main
provenance of dust is the dry regions of the low to middle
latitudes, it is also important to investigate the strength ofhigh latitude dust sources of the past and future, becauseof the high amplitude of their climate changes due to polar
amplification. In addition, it is also necessary to integrate
the processes concerning permafrost into Earth-systemmodels.
It is particularly necessary to advance paleoenvironmental
reconstruction of the permafrost in northeastern Siberia
and Alaska, where little information is available fromglaciers and ice sheets. For the studies of depositional
layers of permafrost, glaciological methods are applied to
Yedoma, and biomarkers are utilized for sediments. For
example, environments from the late Pleistocene to the
Holocene have been reconstructed based on age
determination, and stable isotopic ratios, of water fromunderground ice (Meyer et al., 2010). This work has to beextended temporally and spatially. While paleoenvironmental
reconstruction based on geomorphology (glacier-margin
topography) for investigating permafrost has problems(e.g., coarse temporal resolution and low accuracy), it
remains useful for adding constraints regarding geographicaldistributions of permafrost, and thus should be reevaluated. The reconstructions of surface temperature
history based on temperature profiles of permafrost

Q5: Were the natural variability on timescales from years to centuries in the Arctic different
from today? What are the mechanisms?
While the AO is primarily an internal variability (mode)of atmospheric circulation with a time scale of ca. 10 days,
long-term variability of years to several decades is also
known. For example, a winter trend lasting several
decades was seen near the end of the 20th century and apositive AO trend is seen in predictions for the 21st
century. In order to investigate long-term characteristics
of variability, several studies attempted reconstructions ofsuch variability by employing proxy records from the past
several centuries. While relatively many time-series data
have been reconstructed for the North Atlantic Oscillation(NAO), which is specific to the North Atlantic Ocean, alimited number of reconstructions have beenaccomplished for the AO of the entire Arctic region.
Only coverage of the past 1000 years has been
attempted in studies employing climate models. While
this mainly stems from limited computer resources, there
are other limitations. For example, there is great
uncertainty regarding external forcings, such as solar
activity and volcanic eruptions, which drive climate
models. Earth-system models of intermediate complexity(EMIC, relatively simple climate models) were primarily
employed for simulations at the time when the Fourth
Assessment Report of Intergovernmental Panel on
Climate Change (IPCC, AR4) was published in 2007.

a. State of the art of research
Today, Arctic Oscillation (AO) dominates the interannual variations of atmospheric circulation in the Arctic
region (see Theme 5). The importance of other modes has
also been pointed out for sea-ice transport, and for theentry of warm water masses into the Arctic Ocean fromthe Pacific (see Theme 1, Theme 2). While it is highly
important to understand natural climate variability on
timescales from years to centuries for predicting futureclimate, their statistical characteristics, and themechanisms for their variability on long time-scales, are
not well understood. One of the reasons for thisshortcoming is the short interval over which instrumental
data has been collected. Furthermore, it is complicated tocharacterize the cause of natural variability because therecent climate has been influenced by anthropogenic
activities such as increase in greenhouse gases.
Reconstructions and modeling of paleoclimate covering
the past several thousand years, provide the means to
overcome these problems and may lead to understanding
natural variability, including climatic responses to solar
activity and volcanic eruptions. The characterization ofanthropogenic effects will be useful for prediction of
future conditions, once natural variability can be taken
into account.
63

rapid climate change that has taken place in the 21st
century, and considerable potential has been provided by
new proxies, the analysis of which have recently become
possible due to the advancement of analytical techniques(e.g., black carbon, trace metals, organic matter, and 17O).
All this makes it highly desirable to drill new samples on
glaciers and ice caps in the circum-Arctic region. Several
countries including Japan have sporadically conductedindependent research on ice cores from high mountains(Kamchatka, Yukon and British Columbia in North
America, Caucasus, Mongolia, and Altai). In the future,effective research strategies will require international
cooperation aimed at integrated understanding of paleoclimatic
data.
Oxygen isotopic ratios of ice cores, which have been
widely used as a temperature proxy, are affected not only
by regional temperature, but also by the transport routesof water vapor, and the temperatures of their specificsource regions. As an alternative method for temperaturereconstruction, physical methods based on isotopic ratiosof argon and nitrogen have been developed (Kobashi et al.,2013 and references therein). It is important to apply thismethod to many cores, and therefore reconstruct patternsof regional climate variation. Similarly, it is necessary toreconstruct the variability of Arctic air temperatures andatmospheric circulation, and to advance interpretation, by
employing oxygen-isotope-ratio data as constraints fordata-assimilation techniques used with isotopic models(Yoshimura et al., 2014).
Significant factors limiting interpretation of modelresults are large uncertainties in external forcings such as
solar radiation and volcanic aerosols, which are input data
for models. While multiple data sets are used in recent
climate simulations, the model experiments are notnecessarily carried out comprehensively due to limitations
in computing resources. Improvements in the accuracy of
external forcings are essential for reliable comparisons
between simulated climatic responses and paleoclimaticreconstructions. Concerning volcanic forcing, data setswith significantly improved accuracy have been reported
based on combined analyses of many Antarctic ice coresand Greenland NEEM cores (Sigl et al., 2014). Augmentationof the Greenland data is anticipated to provide better
quantitative estimation of volcanic forcing. It has also
been suggested that solar activity and volcanic eruptions
affect climate in the troposphere through stratospheric
responses, thus simulations using models with sufficient
resolution in the stratosphere are needed. Furthermore,
due to weak external forcing, many numericalexperiments are needed for the past millennia, to extract
statistically significant signals from the simulated climatic
responses. It is also necessary to establish model
infrastructures that will support parallel usage of high- andmedium-resolution models with the same physicalprocesses, for effective use of computational resources (seeTheme B). Furthermore, the Atlantic meridional
overturning circulation (AMOC) is considered to playmajor roles in decadal to century-scale climatic variations,which has attracted international research. Collaborative
studies involving many AOGCM experiments andpaleoclimatic data are needed, and it is essential toestablish sufficient computing infrastructure.
Through the above-mentioned research, thepaleoclimate research community is expected to clarify
how and why the intensity and spatial patterns of pastnatural fluctuations are different from those of today.

Later, many results from the Atmosphere-Ocean General
Circulation Model (AOGCM) were published in the Fifth
Assessment Report (AR5) of the IPCC, and analyses of
temporal and spatial variation patterns became possible byemploying multiple models. Part of the background ofsuch advancement, was that the Paleoclimate Modelling
Intercomparison Project Phase III (PMIP3), an international
project, had established common forcing data andproposed experimental settings, and the PMIP3 was
supported by the Coupled Model Intercomparison Project
Phase 5 (CMIP5). Japanese AOGCMs also participated inexperiments covering the past 1,000 years, thencontributed and published the results to CMIP5/PMIP3(Sueyoshi et al., 2013). In those studies employing asingle model, the relationships between solar activity andthe AO, and between volcanic eruptions and the AO or
Pacific Decadal Oscillation (PDO), have been pointed out.
As a result of these advances and activities, analyses ofsimulated climates using multiple models are being
initiated.
It is well known that the changes in the Greenland airtemperature are affected by the NAO. Moreover, in
paleoclimatic studies, it has been reported that oxygenisotopic ratios of Greenland ice cores correspond wellwith the proxies of NAO. In addition, it was found by aresearch team led by Japanese scientists, that variations inGreenland air temperatures on decadal to century scales
deviated from the average trend of the Northern Hemisphere.
The proposed cause for this is modulations of NAO-likepatterns driven by variations in solar activity (Kobashi etal., 2013).
b. Future research
Climatic parameters such as air temperature areaffected by both global and regional climate changes;
therefore, it is desirable to obtain proxies from many
locations, with consideration of spatial patterns, in orderto reconstruct regional climates (e.g., changes inatmospheric circulation). Thus far, collection of proxy
data have mainly been limited to middle latitudes of theNorthern Hemisphere, and insufficient data have beenobtained from the Arctic region. It is thus important toparticipate actively in projects such as the Past Global
Changes (PAGES) 2k consortium, which is focused on thepast 2,000 years, and to construct data sets integrating
multiple stations to cover the Arctic region.
The paleoclimatic and paleoenvironmental informationthat can be obtained from ice cores is extremely importantin the Arctic region, where long-term instrumental data
are lacking. In Greenland, in addition to deep ice-corestudies for long-term climate reconstructions (such as for
glacial-interglacial cycles), shallow ice-core studies arealso conducted for environmental reconstructions over the
past several hundred years. These have been led byresearchers in the USA and Germany. Concerning the
NAO and its effect, it is important to clarify regional
patterns, and the causes of the decadal-scale NAO, byconducting new drillings and analyses of ice cores fromsites in places such as Greenland, Canada, and the SvalardIslands.
On glaciers and ice caps in the circum-Arctic region(except in Greenland), several countries including Japan
have conducted ice-core research in Arctic Canada, Arctic
Russia, and the Svalard Islands during the 1990s andthrough the early 2000s. At present, there is a wellrecognized and pressing need for reconstruction of the64Box 1Development and interpretations of paleoenvironmental proxies and dating methods

Paleoclimatologists employ proxies (proxy indicators) to reconstruct past climates. Paleoclimate archives
include ice cores, marine sediment cores, lacustrine sediment cores, stalagmites, loess deposits, coralannual rings, and tree annual rings. For example, the oxygen isotopic ratio of benthic foraminifers, theremains of which are found in marine sediments, is a proxy for terrestrial ice volume. Dating (agedetermination) methods of paleoclimate archives are also important, and they include counting of theannual varves of sediment cores, analyses of radionuclides (using half-life), and correlation with pastvariation in insolation (determined by astronomic calculations).
Although proxies play central roles in paleoclimate research, all proxy records entail calibration errors,
and there are many proxies for which it is difficult to quantify the error. In the future, it is important that
there be more cooperation among proxy and modeling studies, in order to improve the interpretation ofproxies. Important tasks include (1) modern observation of proxy formation and preservation (e.g.,
isotopes of water vapor and rain, atmospheric composition, and aerosols), (2) method development ofprovenance estimation by aerosol isotopic ratios (e.g., sulfur and lead), (3) development of analyticalmethods for new chemical and gas composition and isotopic ratios, (4) high temporal resolution analysesof samples, and (5) development of dating methods. Some of the most important proxies are described
below.
a. Paleoclimate proxies in ice cores
Stable isotopic ratios of oxygen in water (18 O) are widely used. However, because 18 O values are also
affected by factors other than air temperatures (e.g., seasonal variation in snowfall), the isotopic records
must be calibrated using other temperature reconstructions (e.g., borehole temperatures and gas isotopic
records). In other words, accurate air temperature estimation by 18 O requires consideration of the entire
hydrological circulation system. In recent years, efforts have been made to estimate simultaneously thepast temperatures of ice coring site, and water-vapor source using oxygen and hydrogen isotopic ratios(Uemura et al., 2012). In addition, the data assimilation technique is also promising. With this technique,temporal and spatial distributions of circulation fields in a GCM are corrected to match the computed
isotopic ratios of precipitation with observational data (Yoshimura et al., 2014).
The aerosols in ice cores are present in various chemical phases (e.g., solid micro particles, liquid
droplets). The chemical forms of water-soluble aerosols, which are proxies for the chemical environmentof the atmosphere, are lost when subjected to the usual methods of ice core analyses, in which thesamples are melted and the ion concentrations in the meltwater are measured. A new method, which
directly analyzes aerosol particles by sublimating ice, has been developed in recent years (Iizuka et al.,2012), and it has begun to be applied to the Greenland NEEM ice core. Other new methods include
measurements of the concentrations of heavy metals, organic carbon, and black carbon, and thereconstruction of aerosol provenance and transport pathways by isotopic analyses. Reconstructions of CH4
and N2O concentrations have been done directly via gas analyses of ice cores (NEEM community
members, 2013) and their isotopes are also analyzed. Surface-temperature reconstructions and detectionof surface melt are now possible based on nitrogen and noble gas concentrations and isotopes (Kobashi
et al., 2013; NEEM community members, 2013).
Advances in these proxy studies will require multiphase research developments. These include
development of isotope and transport models, observations of water vapor, rain, snow, and aerosols, aswell as better understanding of preservation processes of various substances in ice, and better
understanding of ice-core drilling and analyses at many sites. While ultra-high-resolution analyses of ice
and gases with continuous ice-core melting systems are becoming practical in Japan, further
developments are important in order to advance multiple-component analyses involving many ice cores.
b. Sea-ice proxies in marine sediments
There are well-utilized sea-ice proxies found in marine sediments: ice-rafted debris (IRD), iron oxide
particles, microfossils (diatoms, dinoflagellates, benthic foraminifers, and silicoflagellates), biomarkers (inparticular, IP25). IRD is deposit transported by sea-ice and icebergs. IRD can be fractionated using a 63
μm sieve because it contains particles > 63μm. The weight of the IRD fraction can be measured toestimate the IRD mass. Iron oxide particles are widely distributed on the continental shelves of the Arctic
Ocean and the chemical constituents found in them are characteristic of certain regions. Iron oxide
particles can be extracted with a magnet, and the constituent elements of the particles are analyzed toestimate the provenance of sea-ice formation. Because sea-ice related phytoplankton and benthos, suchas some diatoms (ice algae), dinoflagellates, and silicoflagellates, grows in the water and on the bottom
surface of sea-ice and can be preserved in sediments in the regions of seasonal sea-ice and sea-ice
margins, their microfossils can be used as indicators of seasonal sea-ice and/or sea-ice margins. Because
benthic foraminifers also grow in the regions where sufficient organic matter is available, their fossils can
indicate the disappearance of seasonal sea-ice. IP25 is a characteristic lipid specific to algae that dwellon the bottom surface of sea-ice; thus, regions with active sea-ice melt can be determined by its presence.
---------------------------------------------------------------------------65

Theme 7: Effects of the Arctic environment on human society
Abstract

expands in the Arctic Ocean. Since the Arctic Ocean is asemi-enclosed basin influenced by river water, the deep
basin and bottom sediments, the variability in nutrient
distribution is complicated. In addition, it is the first placein the world to suffer marine acidification. As for fisheryresources suitable for the Arctic Ocean, we should beconcerned with resource management, keeping in mind
the serious impact on the residents who rely on fishing andhunting sea creatures. In order to safely operate the Arctic
sea routes, effective prediction of sea ice conditions isessential. In addition to pollution associated withaccidents such as groundings, livelihoods may be
modified by shipping, therefore development should be
conducted with consideration of the impact on residents.
By using examples from the alarm system in Japan forearthquakes and tsunami, we propose a method to copewith environmental problems that will be acceptable toresidents with a livelihood in the Arctic. The important
point is cooperation with indigenous peoples, who
account for the majority of the population in the region,and not forcing them to accept the methods in thedeveloped nations. We will present research on the impact
on human societies and the countermeasures taken,
including information on humanities and social sciences,and propose measures to be taken at each level ofinternational relations, and the national and local
governments. The basis of the long-term plan is to develop
cooperation between the natural sciences and thehumanities and social sciences across the Arctic area,
which will extend beyond the existing environmental
research community.

The five academic questions in this theme are as
follows:
Q1: How do the impacts of climate change, including
global warming, appear?
Q2: What apparent effects in the terrestrial environmentchange due to global warming?
Q3: What apparent effects in the marine environmentchange due to global warming?
Q4: How do the impact of solar activity and the Arctic
upper atmosphere appear on the human societies?
Q5: How do the human societies in the Arctic respondto these impacts?
In the Arctic area, the natural environment is rapidlychanging, for example, sea ice reduction, permafrost
thawing, and changes in terrestrial vegetation and wild
animals, caused by proceeding global warming along with
development from the last century. As implied by theincreasing interannual variability, unusual weather
episodes that we have never experienced are likely tooccur more probably. Fluctuations in climate and weather
differ according to the region; therefore, the priorselection of suitable varieties is necessary for effective
agricultural production. Vegetation and wild animals areseriously impacted by environmental change, including
forest fires, which causes significant problems forresidents with a livelihood in hunting. Disturbances
caused by solar activities create communication failures in
the polar region. As such, it is necessary to intend topreserve the environment and living conditions by taking
measures and advantage to reduce the emission ofgreenhouse gases; for example, carbon credit.
As the sea ice retreats, seasonal ice cover basically

Introduction
effective transfer of information on ongoing and possible
In this long-term plan, our basis for discussing
effects. In addition, we propose measures that can be taken
environmental changes that have occurred to date and thatat levels of international relations, and also national, andare predicted to occur this century is the natural science;
local governments.
i.e., the focus is on mechanisms and effects of global
Let us list predicted problems, with a focus on societal
warming, and on the effects of other anthropogenic
concerns. As climate changes, air temperature fluctuateschanges (including development) on ecosystems. The
and precipitation varies, with different tendencies inoriginality of Theme 7 is in describing research directions
different regions. Agricultural production is sensitive towith regard to effects on human society and potential
countermeasures, including throughknowledge derived from the humanities
and social sciences. While considering
effects on livelihoods of local residents,
we describe methods to reduce negative
impacts and disasters occurring due tounusual weather, forest fires, permafrost
thawing, changes in wild flora and fauna,and solar activities. As for the effects ofArctic environmental change on industrial
activities, we list possible problems andsolutions for operation of the Arctic sea
route, and for future agriculture andfisheries under predicted climate change(Figure 26).Here, it is noted that both
Arctic sea route and Arctic shipping routeare used in this report with the common
meaning. It is shown that cooperation with
Figure 26: The impacts of the Arctic environmental changes on thelocal residents is indispensable forhuman society
66research, it appears that human activities not only induce
environmental disturbances but also possibly contribute tomaintenance of biodiversity. Some have pointed out thatbiodiversity and cultural diversity depend on each other.
Following the decline in sea ice, the Northern Sea
Route between Asia and Europe is rapidly looking likely
to become operational. For safe operation, effective
predictions of sea ice conditions are essential. Should
there be accidents resulting from, for example collision
with icebergs and grounding, pollution will persist forlong periods. The effects of the Arctic Sea Route(including the Northwest Passage on the Canadian side)
are not limited to pollution, since livelihoods may also be
modified by shipping. Development should therefore be
conducted taking into account the various effects on
residents. We propose a method for coping withenvironmental problems similar to the alarm system
adopted in Japan for earthquakes and tsunamis, providing
the indigenous peoples to accept resolutions proposed.
Cooperation with indigenous peoples is important, but
without forcing them to accept the methods in use indeveloped nations.

air temperature and water resources, and it is hence
necessary to select varieties suitable for cultivation inadvance. As inter-annual climate variability increases, inaddition to specific trend changes, terrestrial vegetation
will be seriously impacted, so as wild animals of theregion; causing significant problems for residents withhunting-based livelihoods.
In the Arctic Ocean (including the Siberian Shelves andthe Barents Sea) and its adjacent seas (the Bering Sea,
Greenland Sea, etc.), there will be changes in the marine
environment (such as in levels of nutrients in seawater) in
response to sea ice decline. At present, seasonal ice coveris expanding in the Arctic Ocean, but given that the Arctic
is a semi-enclosed basin, with a relatively large inflow ofriver water and that it is also subject to the effects of deep
basin and bottom sediments, we need to keep in mind
more complex changes. In addition, ocean acidification isgoing to be the most significant first in the cold seas. The
fact that some fishery resources may be more suitable fora warming Arctic Ocean raises resource management
concerns. There may be serious impacts on residents who
rely on fisheries and marine mammal hunting. Withreference to recent viewpoints in ecological conservation

Q1: How do the impacts of climate change, including global warming, appear?
environment to which they have tried to be adapted.
Taking the example of wheat, a main staple food globally,
damage to winter wheat production is dependent on snow
depth in North America, i.e., winter wheat in the groundwithers with frost damage under conditions of lower snow
cover, because snow acts as a good-quality insulationmaterial. Under average conditions, benefits increase(decrease) by 300 million US dollars with a 1 cm deeper(shallower) snow cover (Steppuhn, 1981). In many cities,
residents’ daily lives and industries are supported by awater supply that is dependent on melting mountain snow
and glaciers. Most glaciers have been reported to haveshrunk under global warming conditions, creating serious
concerns of water resource depletion in the near future,
particularly for inland cities.
We have used the example of snowfall levels as an
example here, but many other unusual weather conditions
createhumandisasters,
directdamagetoagricultural/industrial production, and also damage tosocial infrastructure. Such weather conditions include, forexample, heavy rain, drought, tornadoes, typhoonhurricanes, and high tides.

a. Unusual weather(1) Present status of unusual weather
Global warming results in air temperature rise near theland surface, while it has also been shown to induce
significant changes in seasonal weather cycles (See
Theme 1). Maximum summer air temperatures haverecorded large increases in many parts of the world,
leading to human disasters such as heat stroke and damage
to agriculture due to drought and high temperature failures.
On the other hand, never-yet-observed cold waves areaffecting some locations worldwide, resulting in majordisasters in urban societies. Associated with amplificationof seasonal cycles, various natural disasters occurring due
to unusual weather have also increased around the world
including large-scale torrential showers, floods, heavy
snowfall, and frequent tornados.
(2) Impacts on society
An example of impacts on society arises from the heavy
snow cover (30–80 cm) that occurred in February, 2014
over the Kanto region, where snowfall is usually minor. A
heavy snow warning was issued and people experienced
major disruption to their lives, for example with thecollapse of housing and interruptions to the transportation
system. This case constitutes a natural disaster due tosnowfall variability exceeding the location-dependentthreshold. In the same year, similar disasters caused bysnow and ice occurred in the North American continent,
resulting in devastating airline damage, even for airlines
with advanced modernization. In the East Siberian interior,an increase in snowfall amount occurred due to wetting,and central Asia and Europe also suffered many disasters
due to cold waves and heavy snow. With the recent
warming trend, these disasters due to cooling and heavy
snow have occurred more frequently in many parts of theworld than they used to previously.
In most areas, global warming is occurring and isreducing snow and ice. Even in such cases, communities
are still susceptible to disasters, given changes to the(3) Future research direction
We need to scientifically predict global warming
tendencies and climate variability, and to estimate theprobability of disaster occurrences. In addition, we needto build a robust living foundation for coping withdisasters. For this purpose, we should keep analyzing thehistory of mankind using reconstructions of thepaleoenvironment as one method. During periods ofrepeated warming and cooling, historical turning points
occurred mostly as a result of the impacts of unusual
weather. The Ur kingdom of Ancient Mesopotamia, whichprospered with control of water resources, declined due towarming and drying, becoming a ruin in the desert. The
Vikings constructed settlements and camps in Greenland
and northwest of Canada during the warm period of themedieval ages; however, they abandoned these territories
67

Figure 27: The areas burnt by forest fires caused by lightning since 1956 in Alaska indescending orderrelationship with organic matter in the permafrost and on
the forest floor. We can identify recent features of forest
fires in Alaska from Figure 27, which lists forest fires
caused by lightning in descending order of burnout areas.
Large-scale fires, which exceed the burnout area of 6500
km2, were observed eleven times in the past 58 years,
about once a decade over the 1950s, 1960s, 1970s, and1980s. Such fires then occurred three times in the 1990s
and four times in the 2000s. The total burnout area of
46000 km2 in 2004 and 2005 is close to 10% of the forest
area in Alaska. In Siberia, human-made forest fires haveincreased following development and have also beenenhanced by unusual weather events.
Through research on forest fires and vegetation in midAlaska, fire behaviors and vegetation variability wereanalyzed over the past ten thousand years. It has beensuggested, from analysis associated with climate change,that recent intense fires exceeded the limit of burning,although fires may fit vegetation change well similar to
the warm period of the medieval ages (MWP) (Kelly at al.,2013). However, we do not yet have an explanation for
why the limit of burning was exceeded in both cases.

since they could not maintain trade due to the closure of
trade routes by sea ice at the beginning of the Little Ice
Age. These events tell us that civilizations have had theability to respond to frequent minor climate variations, but
could not deal with large changes that exceeded certain
thresholds and resultant unusual weather, otherwisechoosing to migrate to a different location. Although we
do not subscribe to the hypothesis that the environment
determines everything, we should take serious
consideration of the fact that large environmental changes
have been key players in history.
We expect detailed comparisons between historicalevents and analysis results of climate variability records
developed in recent years, derived from ice cores andpollen. It is necessary to carry out quantitative studies byadvancing research collaborations across academic
disciplines, looking at how human activities were affectedby, dealt with, or declined due to unusual weather (such as
heavy rain or drought, high or low temperatures, heavy or
light snowfall, etc.). Based on these studies, we will havea basis for examining social response capabilities withrespect to future climate changes in the Arctic and its
adjacent areas. The indigenous population living in thepolar environment has, until now, conventional
knowledge related to weather, with this having value interms of intangible cultural heritage for humanity. We will
document and record this knowledge and evaluate it fromthe viewpoint of the natural sciences, with the expectationthat it may help identify possibilities for dealing withunusual weather in future.

(2) Impacts on society
Large-scale forest fires, which have occurred frequently
as a result of rapid climate variability in recent years, haveeffects not only on vegetation renewal, the carbon cycle,
and permafrost areas, but also on the acceleration of
global warming through emissions of carbon dioxide andmethane. Furthermore, pyrocumulus formed from smoke
has parasol effects, containing carbon particles similar to
those emitted during a volcanic eruption, and these reduce
the albedo of snow and ice surfaces. Thus, fires cause
environmental problems on a global scale. For
communities in the regions, research activities with a wide
perspective are required to enable preparation for fires,
mitigation of air pollution, assessment of fire impacts,
information transmission to residents, and other suchaspects.

b. Forest fire(1) The present status and research of forest fire
The boreal forests (Taiga) are distributed over thenorthern parts of North America and Eurasia, accounting
for about one third of the global forest area (about 10% of
global land area) and 30–40% of the carbon stock on land.
Forest fires act as a natural regeneration process and as themost significant factor of disturbance, having a close
68Figure 28: The averaged winter 500hPa geopotential height anomalies in the top five years of the frequent cold
Arctic Outflow Events (left), and the third EOF associated with the same ECMWF geopotential height data (right)

large-scale fires by prescribed fires, which are deliberately
started in areas with growing vegetation mass. These canbe predicted with satellite images and using hot spot data.
Although it is difficult to forecast an extreme event relatedwith a blocking high pressure, we can identify theoccurrence of the extreme event from wind directions.
This type of information can be transmitted through the
Alaska Interagency Coordination Center. We can obtain
the results of the latest research, as collected by the Alaska
Fire Science Consortium.

(3) Future research direction
Recent studies suggest that strong easterly dry air winds
from Canada are one of the causes of large-scale forest
fires in Alaska. This weather pattern is related tovariations in atmospheric circulation, i.e., the rapid
decline in sea ice cover in the Arctic Ocean tends to reduce
the temperature difference between the high and low
latitudes and also to weaken the high latitude jet stream,by which the atmospheric pressure ridge develops over
Alaska along with the Beaufort high pressure (see Theme
5). We should carry out more detailed analyses tounderstand forest fire mechanisms that are different fromthe response to vegetation change in the MWP. It is
important to quantify accelerating effects on global
warming by monitoring emissions of carbon dioxide andmethane associated with forest fires.
If we can predict a large-scale fire at the same level ofthe sort that occurred in 2004 and 2005 (with a burnout
area of about 20000 km2), and manage the damage it
induces, it will be possible to reduce emissions of carbon
dioxide to one tenth, because fires other than the top
eleven shown in Figure 27 have burnout areas of about
2000 km2. We can mitigate air pollution emitted fromc. Agricultural production(1) Atmospheric circulation variability
We expect that regions with potential for agricultural
production will expand in the Arctic due to environmental
changes, even though there are some concerns withrespect to the effects of weather conditions. Weather
conditions are highly dependent on atmospheric pressure
distribution, analyzed through principal components as
widely used in atmospheric science. The first mode of theempirical orthogonal function (EOF-1) with the largest
amplitude is derived from pressure at 500 hPa (heightabout 5000m) over the northern hemisphere, representing

Figure 29: The actual and predicted yields of spring wheat in the prairie region of Canada (red area in bottom left)taken from Canadian Prairie Crop yield data (2012), Agricultural Division of Statistical Canada

69

increasing global safety awareness of and resistance togenetically modified (GM) foods; for this reason, there is
growing demand for grains that are not geneticallymodified (non-GM). However, it has been pointed out that
non-GM crops have reduced productivity and are also
weaker under unusual weather conditions. The type ofsoybean used for fodder has been genetically modified tobe resistant to weed killers, and it is hence difficult toselect a non-GM kind.

the Arctic Oscillation (see Themes 1 and 5). This mode
has been found to be related to unusual weather in various
regions of the northern hemisphere (Tanaka, 2008). The
two following modes are also derived in the order of larger
amplitudes: EOF-2 as Dipole Mode (see Theme 5) andEOF-3.
If we look at the prairie region in Canada, we can
examine the spring wheat yield in a unit of plant area, andthe temperature and accumulated precipitation over theperiod from planting to harvest. Under the Arctic Outflow
Event (AOE), cold and dry conditions are expected toappear in winter (Dec–Feb) along the west coast of
Canada, resulting in a yield reduction during the following
spring. The pressure anomaly at 500 hPa is averaged forthe top five years, with many AOEs over 30 years (Figure28), showing a pattern similar to EOF-3 and providing
supporting evidence for the relationship between weather
and spring wheat yield.

(3) Future research direction
It is necessary to apply methods that have been
established for the prairie region in Canada to otherregions in the northern hemisphere, constructing a system
to predict yield in advance of harvest by a few months.
Cold region farming used in Hokkaido has been tested in
the Amur district of the Russian Far East. We could
contribute to the stability of agricultural production in the
Arctic Area by experimentally supplying yield prediction
information in the Amur district. According to the hearingof the 39th International Food and Beverage Exhibition(FOODEX Japan 2014) in March, 2014, higher yields ofalmonds were predicted between the autumn of 2013 andthe spring of 2014 in Australia; however, yields in
California were predicted to be lower. By referring tosignificant differences in agricultural production between
northern and southern hemispheres, we can widen thescope and coverage of research.

(2) Impacts on agricultural production
The predicted yield variability approaches actual yield
if we include EOF-3 as an explanatory variable, in
addition to air temperature, precipitation, and the previous
year’s yield (Figure 29). Since EOF-3 persists for a period,
we could use it to select types of crops a few months prior
to harvest.
In the Trans-Pacific Strategic Economic Partnership
Agreement (TPP) currently under negotiation, there is

Q2: What apparent effects in the terrestrial environment change due to global warming?
this reason, impacts may not necessarily be positive.
In cases when methane and carbon dioxide are emitted
from the ground under the effects of thawing permafrost,
reduction in emissions through a number of measuresprovides carbon credits; thus, this is one example ofReducing Emissions from Deforestation and Forest
Degradation (REDD+). In Indonesia, integrated
management of peatland (through the SATREPS Project)
has been proposed, and doing something similar in the
Arctic is therefore not necessarily unachievable. However,a quantitative estimate is required by monitoring emission
rates in both cases, considering scenarios with and without
reduction measures.

a. Permafrost thawing and carbon emission(1) What happens due to permafrost thawing?
Permafrost thawing has been reported with confidence(see Theme 4 and 12), and emissions of methane andcarbon dioxide have been confirmed (see Theme 3).
However, it is not yet well known which greenhouse gases
are emitted and to what extent. The running water fromthawing permafrost tends to extend lakes, and we havemeasured methane fluxes to the atmosphere at spots on thesoil surface of tundra and taiga. In some regions, thawing
permafrost leads to an extreme increase in soil moisture,
damaging forests and reducing the absorption of carbon
dioxide. In cases when thawing permafrost induces
desiccation, carbon dioxide must be emitted from theground. Forest fires are remarkable sources of carbon
dioxide. Continuous measurement of methane
concentrations in the atmosphere has indicated an increase,and carbon dioxide emissions are estimated to cancel out
half the absorption increase caused by activation ofvegetation.
Methane may vaporize and be emitted not only frompermafrost on the ground but also from methane hydrates
in the frozen soil layer under the continental shelf seabed.
There is still large uncertainty regarding the amount ofmethane in methane hydrates and the rate at which thiswill be released.

(3) Future research direction
The main research actions in relation to REDD+ are
quantitative measurements of methane and carbon dioxide
emissions, and proposed means to reduce these. We willpropose technical development to suppress greenhousegas emissions, by cancelling changes in the water
environment caused by permafrost thawing. With regard
to forest changes due to fires, if we can prevent forest fires
that exceed the usual level, it would be possible to convert
measures to the reduction of carbon emissions.
It may be possible to propose measures to reducegreenhouse gas emissions to society. However, eventhough we can propose one-way communication ofscientific and engineering knowledge to residents, thiswould not be an adequate approach. Residents who are
deprived of their livelihood might have to change theirlifestyles. We should avoid forcing them to agree withproposals for carbon reduction by putting them in asituation where they have no other choice. If they have thechoice to maintain their conventional livelihood by using(2) Impacts on society
There is a physical impact of permafrost thawing on
collapse of houses and damage to gas and oil pipelines.
There are seemingly positive-sounding impacts in termsof farmable area expanding and the extension of the
farming period. However, the ground might be submergedby melt water, and sometimes desiccation occurs; and for70

wolves), and also food competition with and kidnappingby wild reindeer. The social structures of northern
indigenous residents, whose livelihoods have relied on
nomadic reindeer herding, hunting, and fishing, are beingtransformed at an accelerated rate, from conventional life
to urban life, under the double load of cost increases for
hunting of wildlife and pasture of domesticated animals.
Social responses to these problems tend to be
symptomatic treatments, such as mitigation of hunting
regulations, acceleration of pest culling, implementationof high technology equipment, and providing economic
aid for traditional lifestyles. As a result, problems of
biodiversity conservation and sustainable use of resource
animals will become more serious.

carbon credits as a support, this would likely help toensure residents’ agreement. Even in this case, we should
avoid forcing a proposal onto them, but rather, we need totake advantage of the knowledge of indigenous peoples,
recognizing differences in value systems. There would
thus be increased mutual support between indigenous
residents and recent migrants. In terms of research
activities in the humanities and social sciences, therequired approach involves recording economic impacts
and analyzing means of support through social policy
theory.
b. Wild flora, wild fauna, and domestic animals(1) Changes in wild flora, wild fauna and domestic
animals
Global warming and associated changes in thehydrologic cycle (drying, wetting, and changes insnowfall and precipitation) lead to a reduction in the areaof distribution of species adapted to cold conditions,conversely encouraging the northward and upward
expansions of southern species. When considering direct
and indirect interactions between various species (such aspredation and competition), as well as a variety of
feedback loops, complicated changes may be produced at
the level of communities, ecosystems, and landscapes (seeQ1 and Q2, in Theme 8). At present, vegetation changes
that are thought to be caused by global warming, wild fires,and land use changes are occurring, and the direct andindirect effects of these changes are reflected in the
behavior and ecology of individual species, as well as
through changes in structures and functions (Post et al.,2013; see Q3, Box 4 and Box 5 in Theme 8).

(3) Future research direction
Changes in the Arctic due to global warming are also
influencing Japan, even though this has no territory in the
Arctic; although Japan is also partly responsible for thesechanges. There are still few Japanese researchers
participating in biological research in the Arctic, although
there are many cases when we could act on our
responsibility to the international community throughtechnical cooperation and educational support for areas inwhich Japan excels. We need to carry out research in both
ecology and management policy, on the basis ofcooperation between Arctic countries and non-Arctic
countries, as well as collaboration with researchers andpolicy makers in Arctic countries. In terms of concrete
actions, we can propose monitoring of biodiversity using
advanced technology, such as satellite transmitters, habitat
evaluation using model simulations (see Q3 in Theme 8),
and integrated management for the protection andutilization of wild flora and fauna (e.g., protected andhunting areas) by introducing the concept of adaptive
management.
In addition, migratory birds and large mammals, suchas reindeer, take on roles of connecting different regional
ecosystems (biotopes) through materials and functions.
Hence, fluctuations in the number of individuals and in thecomposition of species in the polar region influence
ecosystems and society at resting and wintering sites far
away, including in Japan. Collaborative research is hence
particularly important to explore habitat states andfunctions of migratory animals, based on the constructionof cooperative management systems across multiple
nations.

(2) Impacts on society
Changes in behaviors, individual numbers, anddistribution areas of wild animals and plants in the Arctic
area increase the cost of indigenous residents’ traditional
hunting, fishing and gathering activities; and then, in somecases, their activities may become impossible. It is widely
known that, due to separation of fast ice from the coast in
the Arctic area, indigenous peoples have difficulty incontinuing traditional marine mammal hunting andfishing practices. There are also remarkable effects ofclimate change on the hunting of wild animals on land.
Specifically in the case of wild animals and domestic
animals (cattle, horses, and livestock reindeer) that supply
protein to inland regions, various problems are occurring,such as mass death due to ice storms and ice plate
formation, predation due to predator increases (e.g.,

Q3: What apparent effects in the marine environment change due to global warming?
diversity) of phytoplankton. On the other hand, researchfrom a top-down perspective has not sufficiently analyzed
effects of biomass increases of whales and of fish such as
salmon.

a. Sea ice decline, marine product industry advanceand ecosystem deterioration(1) Effects of sea ice decline on marine ecosystem
There have been observations of changes in the
biological pump, which plays an important role inbiogeochemical cycles between the surface layer and theseabed zone in the open ocean, as well as of changes inthe biomass and distribution of large fish (such as salmon)and of Arctic imports of warm species, including whales(see Theme 9). Research conducted from a bottom-up
perspective is not sufficient for understanding the effects
of a declining ice-covered area in summer on primary
production and on community composition (i.e.,(2) Impacts on society
The impacts on marine production industries vary
between the Pacific and Atlantic sectors, depending on
fishery characteristics. For example, Arctic cod is treatedas a marine product and production variability in the
Arctic has direct effects on the marine product industry in
the Atlantic. It also has an indirect effect in the Pacific,
even if here it is not treated as a marine product. However,71

(2) Aspects to be resolved and impacts on society
In addition to navigable conditions, there are someother aspects to be resolved. Once sea ice retreats, waves
become higher, and seawater spray freezes immediately,
fixing to ships in a cold, rough sea. Under conditions ofincreased icing, even large vessels suffer from adverse
impacts on navigation support equipment, such as radar.
There are also a reduction in deck workability andhindrance to cargo handling systems. Small vessels suchas fishing boats risk capsizing due to raised gravity centers.
If prediction of sea ice movement fails, hulls may bedamaged by extremely thick, ridged ice. In addition,
drifting bergy bits and sea ice pieces increase due to global
warming, presenting a greater risk of collision,
particularly since such fragments are difficult to detectfrom a distance. Even if rescue operations are successful,ecosystems would be damaged by environmental
pollution due to fuel spills, with resultant serious impacts
on residents who rely on seafood.
Even though sea route operation is progressing steadily,associated problems could arise. Ports of call arenecessary along the route. There may not be large numbersof vessels, but there will be impacts on the lifestyle ofresidents due to economic effects. Problems that haveoften been observed are likely to occur.

for species other than Arctic cod to be key species, theeffects of production and distribution of cod (such as
pollock and Pacific cod) should be considered in terms of
the supply of marine products to the import destination.
We need to explore not only biological aspects but also
complicated relationships, such as fishermen’s behavior
when considering economics aspects, and trends in themarine product industry under the influences ofinternational relations.
(3) Future research direction
It is predicted that, as global warming proceeds, thedistribution area of fish of the salmon genus will extend to
the Arctic Ocean (see Theme 9). It is widely known thatthese fish carry a large quantity of marine-derived
nutrients (MDN) to the terrestrial ecosystem (e.g.,
Kaeriyama et al., 2013; Koshino et al., 2013). Also, the
MDN transport mechanism operated by these same fish is
expected to occur in surrounding seas and in the terrestrial
ecosystem affected by environmental change in the Arctic
Ocean. Following the northward shift of marine
production resources, their use is growing in the Arctic
Ocean and in surrounding regions. We will analyze theglobalization of the Arctic Ocean with respect to marine
production resources, and evaluate comprehensively theeffects of Arctic coastal communities on ecosystems andon social economy. We will collaborate with otherdisciplinary experts so that we may provide proposals forindustries that affect marine production, such as theshipping and energy industries.

(3) Future research direction
We will build reliable predictions of various sea ice
elements, to ensure safe navigation for economical
purposes. Useful tools include short-term forecasts on a
weekly basis for safety, as well as mid-term predictions at
a monthly term, and long-term projections over annual todecadal time-frames for economic stability. We will carryout research on the mechanical impacts of contact with sea
ice, and also on the effects of hull icing, accompanied byresearch into prevention technology. On the basis of theresearch outcomes, a navigation support system will be
developed for judgment of capability and efficient use of
the Arctic Sea Route. In addition to predicting icing
amounts on new types of vessels, such as tankers andicebreakers, an integrated prediction model of hull icing
will be constructed to ensure the safety of medium andsmall vessels, such as fishing boats. Actually, the latter are
expected to increase given the search for rich marine
resources in the Arctic Ocean. The model would also aim
to eliminate dangers during dock work.
When selecting ports of call, it is important to explain
the likelihood and environmental impacts of accidents toresidents. However, consent would not be likely to beachieved with unilateral explanations based on scientificand engineering knowledge. Research based onhumanities and social sciences is required in order to build
a relationship of mutual understanding between residentgroups having varying livelihoods, languages, andtraditions. The result would enable mutual understanding
between residents and developers. With regard to usage ofroutes, we need to proceed with a full economic
geography assessment of global distribution systems. At
the same time, an approach is required to explore thenature of governance in the Arctic Ocean on the basis ofanalyses of international laws and legal systems in
relevant nations.

b. Sea ice decline, Arctic Sea Route, and marine
pollution risk
(1) Sea ice decline and feasibility of the Arctic Sea Route
Through this century, seasonal ice coverage has been
consistent on the Siberian side, even though the open
water area varies each year (see Theme 2), which
determines the operational period of the Northern Sea
Route for cargo ship sailing. Thick multi-year sea ice still
covers the Canadian side, and hence innovative methods
are required to render the Northwest Passage operational.
Although use of the Arctic Ocean as a route for cargoships may seem realistic, more practical approaches areneeded for operation, including through monitoring andpredictions of the state of sea ice, understanding theoperational impacts on hulls, and planning of effective
operations. For these, interdisciplinary cooperation
between the sciences, engineering, and economics isessential (Kitagawa et al., 2000; Yamaguchi, 2013).
Once the Arctic Sea Route is operational, the length oftime and cost of transportation will be reduced, also
allowing for reductions in greenhouse gas emissions. The
first condition for operation is establishment of a sea ice
prediction method. Some plans are making progress inunderstanding sea ice distribution, ice thicknesses,
melting states in July and August, and initiation offormation in September and October. This achievement
allows for building of a support system for navigation
through ice floes, which includes safety indicators.

72

Q4: How do the impact of solar activity and the Arctic upper atmosphere appear on thehuman societies?
areas, creates geomagnetically induced currents (GIC) in
power lines and pipelines. These currents result in failureof control systems and accelerate metal corrosion, thus
having an impact on the key infrastructure of modern
society. It is known that sudden changes in the magnetic
field during March, 1989 induced electric currents on the
ground; and the resultant electric currents exceeded theallowable limit in the substation transformer of thetransmission line in Quebec, Canada, causing a blackout
affecting six million people.
In recent years, we have been utilizing space via
satellites and manned spacecraft; satellite positioning
systems, such as GPS, are also widely distributed. We
hence need to mitigate the impacts of the upper
atmosphere on these applications. Use of satellite
positioning by the aviation industry is currently promoted
as international policy. Particularly in this case, where
safety is a key priority, technical development is necessary
to ensure safety when considering the properties ofionospheric disturbances. In systems for Long-Range
Identification and Tracking of Ships (LRIT), used todetermine
vessellocationsthroughsatellite
communications, the use of optical fiber networks is being
studied in order to reduce the effects of variations in thesun and upper atmosphere.

a. The effects of solar activities
Many physical phenomena in the upper atmosphere of
the Earth are caused by variations in the solar wind,including the interplanetary magnetic field (IMF) andradiation, constituting energy flows from the sun. In
particular, the solar wind and IMF originating from thesun interact with the Earth’s magnetosphere, generating an
influx of plasma and electromagnetic energy into polar
areas. In the upper atmosphere, this causes large electric
currents associated with the auroras, expansion anddisturbance of the atmosphere, and environmental change
in radio wave propagation. The galactic cosmic rays fromoutside the solar system, which vary depending on solar
activities, have potential effects on Earth’s climate byionizing the atmosphere and increasing cloud formation.
The disturbances triggered by the sun thus havesignificant impacts on the Earth’s atmosphere, although
we have not yet acquired an understanding of these
physical processes and have difficulty in predicting theoccurrence of these phenomena at this stage. Please see
Theme 10 for reference.
b. Impacts on societyHigh energy particles accelerated by, for example, solar
flares cause an air shower in the lower part of thestratosphere and the troposphere, generating a large
amount of radiation (Figure 30). There may come a time
when top level radiation exposure may reach the dose set
as the annual management target for aircraft crew.
Measures should therefore be considered to minimize
health impacts on aircraft crew and passengers.
Geomagnetic variability, which is caused byinteractions between the solar wind and the Earth’s
magnetic field, and also by aurora activities in the polarc. Future research direction
As an element of important knowledge infrastructure
projects supporting human society, we plan to continue
with research that monitors the polar upper atmosphere,
and research targeted at effective and reliable detection ofionospheric disturbances, in cooperation with theengineering field. In particular, it is necessary to aim forobservation of the upper atmosphere by satellites, radars,

Figure 30: Examples of impacts on society due to solar activities partly modified
from the figure in ‘Present and Future of Society of Geomagnetism and Earth,Planetary and Space Sciences’ (SGEPSS, January 2013)73

time simulations of coupled magnetosphere-ionospherethermosphere systems. Please see Chapter 3 of ‘Present
and Future of Society of Geomagnetism and Earth,Planetary and Space Sciences’ (SGEPSS, January 2013).

spectroscopic equipment, and electromagnetic fieldmeasurement from the ground. In addition, we need model
development to accurately predict the reach of solar
energetic particles to Earth, as well as high-accuracy real-

Q5: How do the human societies in the Arctic respond to these impacts?
evacuation is completed in a reasonable time. We need to
conduct actual drills regularly so that residents areconstantly aware of tsunami disasters. For this purpose,disaster researchers in Japan could utilize their own
experiences.

a. Emergency communications for earthquakes andtsunamis(1) The present status of, and research regarding,earthquakes and tsunamis
Large earthquakes have occurred repeatedly in thesouthern part of the State of Alaska, where the Pacific
Ocean plate is subducting. Tsunamis have followed thequakes, for example, following the Alaska earthquake that
occurred on March 28, 1964, with a magnitude of 9.2. In
2002, the Denali earthquake (magnitude 7.9) occurred,having its epicenter within the active faults of interior
Alaska (Tsuboi et al., 2003). There is no record of a hugetsunami along the coastline of the Arctic Ocean, although
it is well known that an earthquake and associated tsunami
could occur even in areas where this is not expected, as in
the case of the East Japan earthquake in 2011. In recent
years, the Greenland ice sheet has been melting, creating
uplift in the mantle under Greenland, with distortion
accumulated in the crust. There is hence the possibility
that large earthquakes could occur within several centuries,
along with tsunamis.

b. Construction of sustainable systems in indigenous
and urban societies(1) Human societies in the Arctic
The foundation for understanding human history, Arctic
nations, and human societies in the Arctic lies in therelationship between various indigenous peoples and thenations surrounding the Arctic Ocean (referred to as
Arctic waters in the social sciences, i.e., Canada, Denmark(including Greenland and the Faroe Islands), Finland,
Iceland, Norway, Russia, Sweden, and the United States).
The concept of borders between modern states became
applicable in Arctic societies only after the early 20th
century. Indigenous peoples, whose ancestors lived before
nations dominated, are populations with a variety oflanguages, cultures, and races. Based on ethnographic
studies of the early 20th century, we know that theireconomy was supported by hunting and gathering, fishing,reindeer herding, and hunting of marine mammals, while
trade was actively carried out between regions.
From the perspective of nations, the Arctic was the landof buried resources. Russia and Canada advanced to the
Arctic area to acquire fur resources, and the United States
extended its activities into the Bering Sea for the whaling
industry. The relationship with indigenous peoples
evolved through wars, trade, and dependence, while theterritorial domination of modern states was establishedthrough the adoption of a similar process in any region.

(2) Measures for mitigating earthquakes and tsunamis
in JapanA tsunami forecast system has been developed in Japanso that a tsunami warning may be emitted immediately
after an earthquake, based on size and location for
purposes of minimizing possible disasters in coastal
regions. It is necessary to have high-precision seismic
networks and to determine epicenters in order to issue aquick and accurate tsunami warning. It is also possible toapply the technology of this system to tsunami forecasts
via existing seismic networks. Since it usually takes ten
minutes or longer from an earthquake to arrival of atsunami, depending on the location of the quake, it ispossible to minimize impact by evacuation, once thewarming is sent correctly using existing seismic
observation systems.

The Cold War and resource issues
Immigrants established resource development bases foranimal and mineral resources, linked via networks. For
indigenous communities, nations’ settlement and national
education policies began in earnest from 1950 (or so)
onwards.
Since the middle of the 20th century, the Arctic has
been a highly militarized space, as symbolized by US
military bases in places such as Greenland and by theSoviet nuclear test site Novaya Zemlya. At the same time,
the Arctic area has also been a space for scientific research.
In contrast to the philosophy of the Antarctic Treaty
reflecting the outcome of the International GeophysicalYear (IGY) of 1957–58, the Arctic was affected by theCold War, also in scientific fields. In this sense, during the20th century, Arctic human society was subdivided into
categories of indigenous peoples, immigrants, soldiers,
and scientists.

(3) Proposal for residents in the Arctic area
For residents to begin evacuation following the issue ofa tsunami warning, it is necessary to routinely ensure that
residents are alert, building on evaluation of tsunami
disasters. It is clear from the history of tsunami disasters
in Japan that education is necessary to ensure that
residents with little scientific background understandearthquakes and tsunamis. It is important to educate
residents about the possibility of a tsunami following anearthquake, based on correct scientific knowledge, and toremind them routinely to flee immediately to high-altitude
places should they feel tremors, or should a tsunami
warning be issued, even without shaking.
Furthermore, it is also necessary to have methods oftransmitting disaster information that are well accepted byresidents. We should start by estimating tsunami height,
selecting refuges, and establishing evacuation routes, incooperation with local governments. The next step is toconduct evacuation drills with residents, making sure thatIndigenous peoples and environmental issues
The states described above changed after the collapseof the Cold War. Mikhail Gorbachev, supreme leader of
the Soviet Union, called for peaceful use of the Arctic in
1987. Finland then played a leading role in 1989 in
74

impacts on local communities that depend on natural
resources? Through the results of research projects basedon the fusion of humanities and sciences, promoted inrecent years, the conventional wisdom (indigenous
knowledge) of communities and its social role have been
better understood. Analyses of resilience, i.e., capacity toabsorb environmental change, have also been conducted.
On the other hand, it has been noted that both urban andrural areas are subject to inundation and erosion damage
because of sea level rise due to melting of the ice sheet
and glaciers, and more flooding due to melting of snow
and permafrost as well as wetter weather conditions.
(Symon et al., 2005).

gathering the eight Arctic nations to ensure environmental
protection of the Arctic, leading to the formation of the
Arctic Council (AC) in 1996. Within this space that had
traditionally been governed exclusively on the basis ofnational sovereignty, an inter-governmental organization
was thus formed to ensure the welfare of Arctic residents(including indigenous peoples), sustainable development,
and environmental protection.
Although the Arctic Council’s decisions are made by
the eight member countries, it is important to guarantee
participation of indigenous organizations as permanent
participants. Indigenous peoples can be involved inconsultation, not just as nationals of the member countries,
but in positions similar to being nationals of indigenousorganizations. This system follows the decision-making
systems adopted by international organizations, such as
the United Nations, in recent years.
In recent years, western Europe, east Asia, and India,
among others, have developed significant economic
interest in the Arctic area. These countries are
participating in the Arctic Council as associate members
or observers, together with NGOs. Arctic human societyof the 21st century has thus started to be constituted ofboth conventionally-configured population members andnew participants.

(3) Future research direction
Direction
We need to apply perspectives of traditional indigenous
research to immigrants, to then establish Arctic
humanities and social sciences via integration of
conventional political and economic analyses performed
for each nation. In addition, it is necessary to analyze
Arctic human society from the perspective of east Asia,
including Japan.
Contents① Indigenous movement in Arctic Ocean governance
We analyze how indigenous movements are organizedwithin regional governance mechanisms, such as the
Arctic Council, and how they operate with respect topolitical claims, inter-organizational cooperation, andcounter-national policy.
② Arctic multiculturalism and identity
The lives of immigrants and indigenous peoples
engaged in resource development and tourism, among
other sectors, have been intertwined via social, economic,
and cultural aspects. For a better understanding of thispoint, we analyze cultural mixing phenomena and theprocess of restructuring identity.
③ Conventional knowledge as cultural heritage, andits development
Indigenous knowledge related to weather and ecology
of indigenous peoples who have lived in the northern
environment has developed through history over several
thousand years; it is therefore of great worth as intangible
cultural heritage of humankind. In addition to collecting
and recording this knowledge, we provide applications todevelop its value further for future generations, based onnatural scientific evaluation.
④ Environmental changes due to global warming andArctic natural disasters
Global warming is producing impacts, not only throughsea ice decline, but also on forest areas, including
permafrost. We therefore characterize disasters occurringin the Arctic and evaluate how local communities andcities could respond.
⑤ Environmental assessment analysis of coastal
communities linked to Northern Sea Routedevelopment and fisheries resources development
The use of seas connecting the Arctic and low-latitude
areas will tend to increase due to warming. We carry out
overall evaluation of the impacts on ecosystems andsocio-economics of Arctic coastal communities.
⑥ Social dynamics analysis of east Asia, Siberia andthe Arctic Ocean
East Asian countries are committed to Arctic problems
from the perspective of resource development and(2) Current status of research
Development and health problems
The humanities and social sciences have explored
Arctic human society, with the main research challenge
being the history and culture of indigenous peoples. Oneof the contemporary challenges is the impact of resource
development. Analysis of the impact of oil and gas
development in west Siberia on indigenous communities
after the collapse of the Soviet Union reported negative
impacts on indigenous communities. For example,
regional priorities were ignored, grazing land was bisectedby pipelines, the environment was degraded due to waste,
and forced migration was induced. On the other hand, it
has been reported that reindeer herding by indigenous
peoples contributes to the food supply of the newdeveloped area. It has been suggested that development
and traditional occupation could possibly coexist. On theother hand, research is underway regarding damage to thehealth of indigenous communities that are dependent on
mammals and fish in coastal regions, due toenvironmental pollutants from mid- and low latitudes
entering and persisting in the Arctic Ocean.
Identity and indigenous movement
It was considered that cultural identity would suffer inthe face of modernization, with increasing nationalization.
However, as can be seen from the organization ofindigenous movements, subjective ethnic and culturalsymbolism is emphasized in the globalized world andfacilitates to sense the idea of belonging as a response ofpolitical and economical dynamism. Particularly in recent
years, indigenous concepts have become cross-regionaland cross-ethnic, constituting an international political‘actor’. As seen in the formation of Kamuchadal in the
Kamchatka Peninsula, the descendants of immigrants also
conduct their own self-identification. Thus, the ethnicity
of Arctic human society is dynamically evolving.
Effects of climate change
Does global warming have any positive or negative75

scientific observation, while China and Korea have also
introduced immigrants and capital into east Siberia,
territory that is contiguous with these countries. By
considering these aspects in a comprehensive manner, we
perform geopolitical and social-economic analyses of theconnection between Arctic human societies and east Asia.
Methods
Construction of research network for Arctic humanities
and social sciences
We will build media to promote mutual exchange andunderstanding across the humanities (with a focus on
indigenous peoples), social sciences (with a focus onnational issues), and natural sciences (with a focus on thehuman environment). In particular, based on knowledge
related to indigenous concepts and related social reality,
as studied in anthropology and law, we build models of
Arctic human societies that can be shared with theresearch community, synthesizing individual analyses.

76

Chapter 6: Elucidation of Environmental changes concerning biodiversity
Ecosystems are affected by global warming and othervarious environmental changes caused by both natural andhuman factors. Here we describe the mechanisms inecosystems and effects on that, and note current status andchanges in biodiversity.

Theme 8: Effects on terrestrial ecosystems and biodiversity
Abstract

and predict future ecosystem conditions in large scale.
Studies and observations on biodiversity of the Arctic
terrestrial regions are not progressed sufficiently due tothe vastness of the region, but further expansion of theinvestigation, networking of the field studies, and studies
on ecosystem and biodiversity under the environmental
changes are required. Changes in the ecosystem will havestrong impacts on animals such as mammals and birds. In
addition, since the effect of the Arctic terrestrial
ecosystems that accumulate large amounts of soil organiccarbon in the vast wetlands on the global carbon cycle islarge, it is essential to enhance both field and simulation
studies that are essential to make appropriate predictions
using explicit reproduction of ecosystem processes.
Here we have three study questions:
Q1: What environmental changes will occur in the
Arctic terrestrial ecosystems due to anthropogenic
factors?
Q2: How is the biodiversity affected?
Q3: What are the impacts on climate and animals dueto the changes in the Arctic terrestrial ecosystems?

Arctic terrestrial ecosystems and its biodiversity are
now exposed to significant changes due to strong impact
of human activities such as global warming. Comparedwith other ecosystems of the world such as temperate andtropical, the expected environmental changes in the Arctic
terrestrial regions are particularly strong (IPCC AR5), andwe have to predict the future conditions by promoting
research and organizing the knowledge about the effectsof the environmental changes. Nevertheless, research on
Arctic terrestrial ecosystems is significantly delayed,when compared with other ecosystems, and a strongemphasis on this topic is urgently needed. In Topic 8,
Arctic terrestrial ecosystems, biodiversity that is an
important component of the ecosystem, and impacts fromchanges in ecosystems and biodiversity on the climatechange and regional communities are considered. Because
Arctic terrestrial ecosystems are now facing serious
changes that caused by human activities, such as
agriculture and forestry and exotic species other thanclimate change, we have to highlight the importance offield observations and experiments, remote sensing, andsimulation studies that integrate spot field observations

Introduction
compiled on the basis of Questions. In Q1, we give an
Terrestrial ecosystems and their biological diversity are
outline of impacts on Arctic terrestrial ecosystems
important elements of the earth system, and these areaffected by artificially-induced environmental changes. In
closely related to the productivity of agriculture andQ2, we focus on biodiversity and discuss requirements forforestry at local scale, with significant impact on the
future studies and measurement. In Q3, we describe theglobal climate through carbon cycling. Terrestrial
impact of changes in terrestrial vegetation on animals, theecosystems are therefore very important and it isimportant to accurately understand theirpresent conditions and prepare for the
future, particularly because of the
pronounced recent direct and indirect
impacts of human activities. Humans
affect many aspects of ecosystems andbiodiversity in the Arctic terrestrial area
(Figure 31). Direct influence involves
impacts of human activities (such as land
use change due to agriculture, forestry,hunting, and mining) in the Arctic area.
Indirect
impacts
constituteenvironmental changes caused byclimate change (such as temperature
increase,
precipitation
change,snow/ice/permafrost
melting,andwildfire). In this theme, in addition to thedirect effects on Arctic human societies(cf. theme 7), we examine indirect
influences on global human society
throughglobalclimateandbiogeochemistry (cf. theme 3). This is a
Figure 31: ATEs and biological diversity are closely related to human life
very important and urgent concern for all,and activity. This aspect is not only of relevance to people living in polar
including us Japanese.
areas, but interacts with global human societies through climate change.
The description of this theme has been77

higher consumers in ecosystems, and feedback to climate
from vegetation changes. This constitutes the output fromthis theme to the whole report.

Q1: What environmental changes will occur in Arctic terrestrial ecosystems due toanthropogenic factors?
climate change; an example is the entry of woody plants
into tundra through northward movement of the tree line.
It is conceivable that an increase in harmful ultraviolet
insolation caused by the depletion of the ozone layer (theinfluence of which is especially significant in polar
regions) will impact ecosystems, although there areprospects of mitigation in sight.
There are also problems arising from both direct
influences of human activities and indirect influences
through climate change. Wildfires have a serious impact
on ATEs, but our overall understanding of theirmechanisms has not advanced, due to the complexities ofignition and other aspects. Wildfire is often caused byhuman activities, as well as by natural ignition (such as
lightning). It has become important to understandmechanisms of wildfire occurrence, including theinfluence of climate change and future prediction, because
the severity of wildfires greatly depends on physicalconditions (such as temperature, wind velocity, and soil
moisture). Furthermore, impacts of wildfire on climatechange are wide-ranging, and with current scientificknowledge, it is not even known whether there is positive
feedback amplifying climate change or negative feedback
to deter it (Figure 32).
Forest plants perform primary production inecosystems, and changes in vegetation influence fauna
and microflora. Vegetation changes result from bothclimate change and direct human activities (such as
deforestation). These in turn influence various ecosystemservices, such as carbon sequestration, as well as affecting
biodiversity. In Q3, we discuss the indirect influence on
animals through climate change. In terms of direct
influence, we must not ignore habitat fragmentation by
deforestation and by construction of roads and railroads.
Habitat fragmentation is a particularly serious problem in
ATEs because there are many migratory animals, such asa. Importance of this topic and current conditions
The terrestrial ecosystems of the Arctic and subarctic
zones (hereafter referred to as Arctic terrestrial
ecosystems: ATEs) have unique characteristics. Species in
ATEs are unique due to severe environmental constraints(such as low temperatures, snow accumulation, and shortgrowing seasons). Since seasonal changes inenvironmental conditions such as temperature areparticularly intense, there are many animals that moveseasonally and that use ATEs temporarily. The necessary
information to scientifically understand ATEs varies,
because these are comprised of two very different
ecosystems: boreal forests (taiga) and tundra (with no talltrees). Because, given their specific nature, ATEs are
sensitive to even slight environmental changes, andbecause climate change is expected to become particularly
intense in this area, we should expect the promotion of
intense research. Knowledge of ATEs should be used forenvironmental conservation.
Artificial environmental change, including global
warming, has strong impacts on ATEs that are expected to
be exacerbated in future. There are various factors ofartificial environmental change; here, we discuss a
representative selection, considering the severity of
impact and present state of scientific knowledge. First,
climate changes resulting from greenhouse gas emissions
are changing the environmental conditions (such astemperature and precipitation) within which ATEs are
established. Second, pollution of the atmosphere, water,and soil becomes a serious concern with the advent ofindustrial activities, including mining, oil fielddevelopment, and hydroelectric power generation.
Whether intentional or not, human activities also result ininvasion of many exotic species, with effects on
ecosystems comprised of native species. It is anticipatedthat southern species will invade northern regions due to

Figure 32: Climate change and wildfire form a complex feedback. +: positive feedback. -:negative feedback. We need to understand the dynamics between climate change andwildfire and whether wildfire accelerate or decelerate climate change.

78

Figure 33: Leaf area index distribution in the circumpolar terrestrial area. (a) Estimate from observation by MODIS. (b)Simulation by the terrestrial ecosystem model (Ise and Sato 2008). Simulations promote understanding of mechanisms
in ATEs and biological diversity, through appropriate estimation of the types and size distribution of vegetation.

understanding and prediction capabilities via simulation.
These should simultaneously be accompanied bycontinuous field observation.
Over the medium- to long-term, observation systems
should be more stable, spatially broader, inexpensive, andreal time. We should therefore emphasize utilization of
automatic observation equipment, including fixed-point
observation cameras and observation networks. It has
become possible to estimate an ecological variable withhigher accuracy by optimizing analysis of remote sensing
data through field observation. In addition, and as Figure
33 shows, it is vital to enhance accuracy of simulation
models for the entire circumpolar terrestrial area,
performing data assimilation through observation, andencouraging the establishment of appropriate future
prediction studies. Based on simulation studies of Alaskan
and European ATEs conducted to date, we should promote
model development and improvements in process models,for example in relation to plant physiology, population
changes, community changes, and biogeochemical
cycling in ecosystems of the circumpolar terrestrial area;
these developments would allow us to improve predictive
capabilities.
In order to conserve biodiversity, we should establish
conservation priorities based on objective evaluations ofvarious species and ecosystems. In this way, it would bepossible to more effectively protect ATEs where
significant changes are expected. We should also define
keystone species and key ecosystems (hotspots) toperform focused conservation. In addition, as Japanese
researchers, there will be a greater demand for us tomaintain close communication with local researchers andresearch organizations in future, and to promote studies
through a mutually beneficial relationship. Given thisinternational framework, it is important to cooperate
constructively with IPBES37, CAFF38, and GEO BON39.

large mammals. In addition, we must consider the effectof human immigration in terms of epidemics and insect
damage in relation to the expansion of infected zones, aswell as considering the effects of climate change.
We also need to pay attention to urban development andagriculture. Historically, human activities such as
agriculture have not been widespread in this area
(particularly inland) and the population density of the area
was low. However, it is possible that human activities
increase in future if the environment becomes suitable forhuman activities through climate warming. It is necessary
to be cautious about future development (for example,
agricultural development through artificial draining ofpeat bogs in Scandinavia). Changes in ATEs diverge into
many branches and their influence may be serious;
however, there have been delays in developing anobservation system to understand present conditions.
Moreover, because biological processes in ecosystems are
subject to theoretical generalization difficulties,
development of models that are applicable to a wide area
in a comprehensive manner has not advanced
significantly; the need for such models has started to be
discussed (Purves, 2013). Since data acquisition to
support validation of such models is often more difficultin the Arctic terrestrial area than in other areas, due to theharshness of the environment, there is expected to beintensive promotion of research for both modeling andobservation.
b. Future studies
First, to understand changes in ATEs and conservationof biodiversity, basic ecological studies (such as studies ofplant and animal physiology and their responses toenvironmental change) are important. It has become more
and more important to monitor wide areas, utilizing
satellite remote sensing, and to develop mechanical37

IPBES: Intergovernmental Platform on Biodiversity and Ecosystem Services
CAFF: Conservation of Arctic Flora and Fauna
39
GEO BON: Group on Earth Observations Biodiversity Observation Network
38

79

experiments will also be an important study topic, inaddition to observation. Furthermore, it will be necessary
to estimate carbon budgets accurately over a wide area
using a combination of satellite remote sensing and fieldobservation.

In the northern forests of Alaska, forest recovery
processes following the large 2004 wildfire are underinvestigation. Recovery processes after tundra fires arealso under investigation (Tsuyuzaki et al., 2009). In future,
based on these results, a plan to clarify short- to long-term
influences of fire disturbance will be developed. Fire

Q2: How is biodiversity affected?
ecosystems is high. However, even though boreal forests
occupy about 1/3 of the global forest area, there has not
yet been detailed investigation and research about their
biological diversity, with some exceptions in places thathave been intensively studied (e.g., super sites around
Yakutsk in Siberia or the Canadian BOREAS site).

a. Importance of this topic and current conditions
In order to understand change in ATEs and to makefuture predictions, it is fundamentally important to
conduct research and gather information aboutbiodiversity (Box 2). However, when compared to lowand mid-latitude regions, interest in the biodiversity of
ATEs is low and studies of biodiversity are scarce. In
particular, there are few studies by Japanese researchers atpresent, but we should highlight the intensification of
future research efforts. Here we describe the current stateof biodiversity research and discuss directions for future
work.
There are two threats to plant species diversity in ATEs:
threatened species and exotic species. Although Red Lists(exhaustive lists of regionally-threatened species) havebeen established for each country and area, it is necessary
to also compile lists that consider other aspects. For
example, there may be a need to consider larger scales
over multiple countries, or smaller scales to develop
specific conservation plans. Given that there have been
delays in compiling a list of exotic species (blacklist), data
integration should be performed as soon as possible.

(2) About peat bogs
The peat bogs that are distributed over circumpolarzones play an important role in global carbon cycling due
to their significant accumulation of organic carbon(Clymo, 1983). Moreover, peat bogs have a unique floraand fauna and are an important ecosystem in terms of theirbiodiversity. Peat ecosystems, which are established on
the border of terrestrial and aquatic ecosystems, haveenvironmental characteristics of both. Biodiversity is highbecause there are varying environmental conditions withfluctuating water levels (Mäkilä et al., 2001). Althoughstudies to analyze the relationship between environmentand biodiversity in peat ecosystems have been conductedin many wetlands, studies analyzing the heterogeneity(variations in space and time) of peat bogs or that analyze
the long-term change have, to date, been scarce. It will benecessary to intensify such research efforts in future.

(1) About biodiversity
Species diversity of the northern forest ecosystems islower than that of tropical or temperate forest ecosystems,
but it is thought that ecosystem variation is so high as toequal that of tropical or temperate forests. The
environment of the northern forests is characterized by
low temperatures and drought, and under suchenvironmental conditions, light stress (i.e., when the lightenergy that plants absorb for photosynthesis becomes
excessive, active oxygen species are produced, damaging
plant tissues) is amplified. This thus constitutes a very
challenging environment for plants to survive in. Plants
use a variety of strategies to live and reproduce here (e.g.,
seed propagation vs. clonal propagation, broadleaf forests
vs. needleleaf forests, and evergreen trees vs. deciduoustrees). In this sense, the diversity of boreal forest(3) About environmental responses
It is also necessary to appropriately examine thediversity of responses of life forms, in order to evaluate
impacts of prospective environmental changes in ATEs.
When considering the stability of ecosystems underclimate change, the importance of diverse ecologicalresponses has been pointed out (Elmqvist et al., 2003;
Mori et al., 2013). Since responses vary with different
places and species, if the diversity of ecological responses
to climate change and disturbance is high, it is thought thatthe ecosystem can tolerate environmental change to alarger degree, i.e., it has more resilience. It is therefore
necessary to evaluate species- and ecosystem-specificresponses to climate change.

Box 2 What is biodiversity?
Biological diversity refers to biological variation (terrestrial ecosystems, marine and other aquatic
ecosystems, the ecosystems compounded these), and is a concept that includes variety at threedifferent levels: (1) genetic diversity, (2) species diversity, and (3) ecosystem diversity (definition
established in the "Convention on Biological Diversity" during the 1992 Rio de Janeiro United
Nations Conference on Environment and Development (Earth Summit)). Genetic diversity isvariation within a species. Ecosystem diversity is the variation in functions and interactions of eachspecies in an ecosystem. The word “biodiversity” conjures up the image of species diversity tomany; however, we should consider not only species diversity but also genetic diversity andvariations in life history and adaptation.

80

properties will be significant. In addition, future
monitoring studies are important because it is possible thatclimate changes in the Arctic terrestrial area (e.g.,
extension of a growth period due to warming) enable newinvasions of species that have to date been limited by thesevere environmental conditions.
It will also be necessary to examine ecologicalresponses to movements of exotic species due to climatechange, given that serious effects on ATEs are anticipated.
This includes those phenomena that may bring about
dramatic changes, such as advance of species from thetemperate zone to boreal forests, and tree invasion into thetundra. In order to understand these phenomena, it isnecessary to clarify ecosystem function changes byidentifying species with the potential to invade ATEs andthrough experiments. Furthermore, while the importanceof ecosystems with high biodiversity is recognized, it will
also be necessary to indicate specific ecosystem functions
in low-biodiversity ecosystems.
Japanese researchers should highlight, in particular,
studies of subarctic ecosystems that are also present inJapan (including Hokkaido as a case study). Given that
there is a strong relationship between the alpine belt of
Hokkaido and the Kuril Islands, Kamchatka, and Sakhalin,
we should use domestic research results to understand theecosystems of the circumpolar Arctic terrestrial area.
Since terrestrial ecosystems feature high local specificity,
it may be possible to make use of studies accumulated inJapan, for example, concerning exotic species and their
management, even if we must be wary of extreme
generalization.

b. Future studies
There are two fundamental needs to address thebiodiversity issues noted above: (1) compiling research
results and knowledge into a database, and disclosing it to
the public; (2) extending the geographical scope of
research. In addition, active promotion of nature
conservation both within and outside Japan will also benecessary. Moreover, it will be necessary to taxonomicallyreclassify scientific names (Box 3).
Research into geographical shifts in biologicalboundaries due to climate change is worthy of special
mention. For example, since the northward advance ofnorthern forest species into the tundra due to warming willbring with it significant changes to biogeochemistry andsurface physical processes, the relevant contributions toclimate change studies will be large. It is important toquantitatively predict these dynamic and transient changes.
Further studies are needed to understand biodiversity
changes and responses of ecosystem functions to climatechange. There is concern that rapid global climate change
not only changes ecological community structures, butalso influences ecosystem functions (Loreau et al., 2001).
Recently, there has been significant progress in studies of
the relationship between biodiversity and ecosystem
functions, and it is thought that a rapid decrease inbiodiversity degrades ecosystem functions (Cardinale,2012). The characteristics of ecosystems with highvulnerability to climate change include low resource
availability and low species diversity. In this kind of
ecosystem, it is expected that the impact of even a slightincrease or decrease in species diversity and functional

Q3: What are the impacts of changes in ATEs on climate and animals?
vegetation changes, wildfire, and land use changes in
ATEs. It is thought that these factors have a significant
influence on the variety of animals inhabiting ATEs
directly and indirectly through vegetation changes.
For example, there have been reports of changes in the
behavior and reduced distribution area of animals such as
musk ox, reindeer, and polar bears (Box4). Several otherchanges are also known; northward movement of forest
herbivores (e.g., squirrels and deer, Box4) and carnivores(e.g., wolves and brown bears), population increases andan expansion of the distribution area of geese, ducks, andswans breeding in the polar area (cf. Box 5), and large

a. Importance of this topic and current conditions
Various kinds of species adapted to severe
environmental conditions in ATEs form a unique biota.
For example, polar bears and blue foxes, which have been
flagship species of conservation in ATEs, are species
whose morphology and life history has evolved to besuited to this specific environment, and they can inhabit
polar regions throughout the year. In addition, migratory
species such as reindeer and waterfowl use rich foodresources to breed during the ATE’s short summer, andwinter at lower latitude; that is also a strategy to avoid
competition with other species. Q1 and Q2 consider

Box 3 Disagreement over scientific names
There has been progress in field studies based on international collaboration, but there are still
problems related to international disagreements on taxonomic names. The distribution of plant
species does not have a national border, but there is often a border in terms of taxonomic name.
Different taxonomic names are frequently used for an identical species in different countries. The
reason for this is that there is no accord on species recognition by countries/researchers (clumperand splitter) and there has been insufficient work in terms of the compilation of databases anddata publication of type specimens/descriptions of new taxa. A universal approach to taxonomic
names that is understandable to ecologists and other researchers is needed. Taxonomic names
should be established for such a purpose from the start, but this is often not the case in practice.
We therefore need international exchanges of specimens and information, including old documents
and types. This demands that we promote use of academic specimens held by each country
through networks such as the GBIF.

81

warming in the Arctic but there are large uncertainties as
to how warming influences plant species and vegetation
distribution related to biological diversity; there is also
uncertainty related to the influence of climate feedback
through carbon cycling and water/energy budgets in theterrestrial area.
Within the permafrost zone of the Arctic terrestrial area,
physical characteristics of water (e.g., fluidity and heat
capacity) largely change with the threshold (i.e., zero
degrees Celsius). Although it is feared that local
vegetation that is intrinsically linked to the climate, frozen
ground, and snow cover may suddenly collapse andtransition to an irreversible state with climate change,
there are still insufficient predictions using mechanistic
studies and numerical computation. In addition, there has
not been much progress in field-based studies ofvegetation in ATEs with respect to understanding biota
responses and life history, particularly in comparison withbiogeochemical studies. There are many unexplained
points regarding responses to climate change.
Furthermore, there are many unexplained aspects relating
to positive-negative feedback to climate change by biota.

outbreaks of pests in the taiga (Post et al., 2013). Future
concerns include further vegetation changes, increases incompetition and predatory pressure, mismatches in thetiming of migration, snow thaw, food production, and the
spread of epidemics and exotic species because ofwarming. Though ATEs are exposed to such serious
changes, there are many uninvestigated responses. Sincechanges in animal populations have a significant impact
on human society (cf. Theme 7), the relationship between
ATEs and animals has to be clarified.
Vegetation changes in ATEs affect not only animals but
also global climate, through processes such as carbon
cycling (related to theme 3: feedback to the atmosphere).
In order to clarify such feedback, earth system models thatincorporate terrestrial ecosystem models into climate
models have been developed so far;which include not only
the carbon cycling models handling carbon dynamics inthe ecosystem, but also the vegetation dynamics models
that able to predict spatiotemporal changes in plant
functional types. However, as compared to land surface
process models that are explained mainly by physicalfactors, the uncertainty of carbon cycling models andvegetation dynamics models based on biological factors is
likely to be high. Models have predicted remarkable

Box 4 Changes in reindeer habits
Tundra reindeer are characterized by seasonal migrations of several thousand kilometers, withwide distribution over the circumpolar region. However, population decreases and a reduction in
distribution range have been reported for many populations. This decrease has also been noted tobe remarkable in east Siberia (e.g., from approximately 1 million individuals in the Taymyr peninsula
to tens of thousands). After tracking approximately 20 individuals using satellite telemetry, it
became possible to reveal influences in terms of behavioral inhibitions caused by warming; relevant
aspects include ice board formation by icy rain and ROS (rain on snow) in early winter, and earlier
river thaw in spring. These individuals gathered in the upstream portion of the Olenek river (theeast end of the Siberian Highlands) where the progress of warming is slowest in summer; however,their migration route and wintering places were not fixed and the ratio of newborns dropped by halfor less compared to 30 years prior. This collaborative Japanese and Russian investigation, carriedout also in cooperation with indigenous hunters (including the Even and Evenki peoples), ledreviews of protected and hunting areas by the Government of the Sakha Republic, and newmonitoring procedures have been adopted by the municipalities of several parts of eastern Siberia.

Box 5

Monitoring of waterfowl

Since most waterfowl distributes over ATEs and overwinters in low latitudinal zones, there should
be global monitoring and the actual state of population change should be clarified. The Japanese
Ministry of the Environment carries out long-term monitoring with NGOs; as a result, it has become
clear that the population of many shorebird species has decreased, but that fluctuations differ byspecies of wild geese, ducks, and swans. Some populations that have spread into ATEs have been
increasing. As a result of warming, the breeding environment temporarily improves in some cases,
but it has been noted that breeding habitats may be greatly affected by vegetation changes in thelong-term, as well as by mismatches in the timing of migration, food availability, and snow melt.
The northward movement of predators, diseases, parasites, and competing species (Ganter andGaston, 2013) may also be a concern. It is therefore necessary to monitor future population
changes.

82

b. Future studies
It is necessary to construct database and monitoring
systems in ATEs so as to understand actual habitat
conditions of animals on a wider scale (related to Q1, Q2,
and theme 7, Q2b). In order to perform effective
monitoring in ATEs that pose challenges for field
investigation, we should mainly identify the species(indicator species, key species), ecosystems, and regionsthat should be investigated (related to Q1), and integrate
existing monitoring data (e.g., CAFF sites and waterfowl
monitoring sites), identifying areas where future researchis needed. In addition to field surveys, large-scale studies
using satellite tracking and airplane investigations are also
necessary, as well as the establishment of researcher
networks (related to theme 7Q 2b), and analysis of longterm population trends of migratory animals. Furthermore,using databases, it is necessary to analyze the relationshipbetween the distribution of animals and the environmental
conditions of their habitat. For example, through animal
observation data and environment data (e.g., climate andvegetation), it is possible to construct statistical models toestimate potential habitats at large scales. Habitat
suitability maps developed in this manner make it possible
to determine new study areas. In addition, it may also be
possible to estimate habitat change under warming
scenarios if a simulation is performed using the vegetation
model (related to Q1 and theme 3). However, because
there are many unexplained aspects of ecosystem change
in response to warming, it is necessary to perform overall
reviews based on literature, identifying unexplained
processes in the relationships between climate andvegetation (Figure 34-①), climate and animals (Figure34- ② ), vegetation and animals (Figure 34- ③ ), andanimals and animals (Figure 34-④). Several field-based
studies will also be necessary to clarify these relationships.
To better understand feedback to the atmosphere(Figure 34– ① ), we need to improve the precision ofcarbon dynamics and vegetation models. For example, itis necessary to acquire vegetation observation data (fieldand satellite data) and to develop related data assimilation
techniques, in order to estimate model parameters (related
to Q1). In addition, through field-based studies, it isnecessary to encourage the elucidation of unexplained
processes and model improvement. It is also necessary to
clarify the actual state of positive-negative feedback to
climate changes from biota (e.g., albedo changes by strong
foraging pressure of reindeer and snow, Figure 34 -③①,
influence on vegetation by large insect outbreaks, Figure34 -③).

Figure 34: A conceptual diagram of interactions among
climate, vegetation, and animal.

83

Theme 9: Influence on marine ecosystem and biodiversity
Abstract

as well as additional influences on material transport,
biodiversity via food chain and competitive relationships.
The change in species diversity significantly affects
productivity and decomposition of the ecosystem.
Therefore, quantitative interpretation of the environments
surrounding the sea-ice ecosystem of the Arctic Oceanand each of the processes and mechanisms in theecosystem is important for assessing the influence on
future sea-ice ecosystem and biodiversity of the Arctic
Ocean.
However, most of the knowledge that has been obtained
thus far is tempo-spatially fragmentary because that it isbased on the limited data from open waters during summer
season when research vessels can safely cruise around in
the Arctic Ocean. Furthermore, the sea-ice ecosystem has
aspects where almost no information is available due tothe complex relationships among physical, chemical, andbiological processes. Therefore, our long-term goal is toclarify the influence of the Arctic Ocean on the ecosystemand biodiversity, not only by conducting multidirectional
observations in extensive areas with the use of ice
breakers and mooring systems, but also by conducting
interdisciplinary research that links process experiments
and numerical modeling.

Because the surface of the Arctic Ocean is extensively
covered by sea-ice, inhabiting marine biota thrive by
adjusting to the unique environment formed according to
the characteristics of the ecosystem. However, the Arctic
sea-ice ecosystem has been disappearing due to the rapid
decrease of sea-ice cover caused by the recent warming.
We now list the following four questions and describe ourlong term view for future research by focusing on thechanges occurring from perennial to seasonal sea-ice
formation, which affect the marine ecosystem andbiological diversity in the Arctic Ocean.
Q1: Are the ecosystem and biodiversity of the Arctic
Ocean significantly affected by the substance inthe atmosphere and from the terrestrial areas?
Q2: How do the biota of the Arctic Ocean transport andchange in quality of substance?
Q3: How the food chain and changes in ecosystem andbiodiversity are related in the Arctic Ocean?
Q4: How does ocean acidification and denitrification in
the Arctic Ocean influence the ecosystem andbiodiversity?
The dramatic environmental changes in the Arctic
Ocean are of concern because, not only is biologicalproduction in the Arctic Ocean altered, but also thedisappearance of biota and entry of new biota may occur,

Introduction
The ArcOD has listed more than 7,000 species andreported that invertebrates and fishes have been extending
their habitats to the north and that the percentages ofwarm-water taxa relative to cold-water taxa haveincreased. Furthermore, the CoML predicted that thebiological diversity would increase in the region of 5070˙N (CoML, 2010). However, it is uncertain how the
Arctic ecosystem and biological diversity as well as therates would change, responding to the anticipatedcontinuous decline in sea-ice cover and marine
environmental change in the future (Conservation of
Arctic Flora and Fauna (CAFF), 2013).
Here, the needed research contents for the future will be
described in order to evaluate the effects of theenvironmental changes occurring on the marine
ecosystem and biological diversity in the Arctic Ocean.
Note that biological diversity is defined in three different
ways in the CBD as “ecosystem diversity”, “species
diversity”, and “genetic diversity” (see Box 2, Theme 8).
We describe mainly “species diversity” herein.

The marine biotas that live in the Arctic Ocean formcharacteristic ecosystem called sea-ice ecosystem byadapting the ambient environmental conditions of sea-ice
and ice margin. However, they are currently facing with
rapid environmental changes, which have not been
experienced thus far, such as the decline in sea-ice cover,that is a basis for the unique ecosystem, and ocean
acidification. Such changes cause disappearance of thebiotas constituting the Arctic sea-ice ecosystem andintroduction of new biotas and therefore the marine
ecosystem will drastically change in the Arctic Ocean.
Furthermore, the changes at the same time mean the loss
and/or increase of biological diversity in the Arctic Ocean.
The Convention on Biological Diversity (CBD) hadconcluded in 1992 that in order to conserve the ecosystemand support the human survival it is important for us toconserve the biological diversity. In the Arctic Ocean,much knowledge has been accumulated concerning
biological diversity by the Arctic Ocean Diversity(ArcOD) project, which was pursued during the 2,0002,010 Phase One of the Census of Marine Life (CoML).

Q1: Are the ecosystem and biodiversity of the Arctic Ocean significantly affected by thesubstance in the atmosphere and from the terrestrial areas?
few years (e.g., McClelland et al., 2012). The results ofresearch include, for example, the delivery of substantial
amount of labile dissolved organic carbon, which canreadily be decomposed by bacteria and photooxidation.
While the direct river discharge of dissolved inorganic
nutrients required for photosynthesis such as nitrogen andphosphorus is small, the effect by the nutrients derived
from terrigenous material on marine primary production
cannot be ignored. Furthermore, the importance of thea. Importance of research and state of the art
Greater than 10% of total dissolved organic carbon, thatis discharged by rivers of the world to the oceans, isdelivered to the Arctic Ocean, but it has been consideredthat most of it was refractory and hence the effects on the
Arctic ecosystem was small. However, the importance ofthe delivery of terrigenous substance to the Arctic Ocean
and the effects on the ecosystem and biodiversity has beenrecognized recently by the research conducted in the last84

Figure 35: Schematic illustration showing material transport from land andatmosphere to the oceans and influences impacting on biotas in the interior of
the oceans. The supply of nutrients and pollutants to the ocean would increase
due to rivers, atmosphere and the processes such as coastal erosion and glaciermelting driven by the global warming. On the other hand in the interior of theoceans, direct and indirect impacts on marine biotas such as accelerated ocean
acidification, stratification, and removal of nitrogen nutrients (denitrification: see
Q4) are also predicted. Red arrows indicate the supplies and removals ofnutrients and pollutants.

terrigenous and atmospheric origin and that can contributein prediction of the changes caused by the global warming.
It is possible in the future that the supply of carbon andnutrients originated from land for marine low trophic levelecosystem would increase by the processes such as theincrease in organic matter supply due to the melting of
permafrost and continental ice sheets, the increase insupply of the material from atmospheric origin, theincrease in activity of microbials due to water temperaturerise, and the increase in light penetration due to thedecrease in sea-ice cover. However, the increased
remineralization of the terrestrial organic matter would
accelerate ocean acidification and negatively impact onbenthos at the same time (see Theme 3, Theme 9, Q4).
Furthermore, the increased supply of freshwater discharge
from land (see Theme 4) could possibly strengthen
stratified marine surface layer, and lower biomass, andcause species change by the limited nutrient supply to thephytoplankton in the surface layer. Moreover, pelagic
biological production can also be affected because that thelowered density of coastal waters can alter transport
pathways of materials from continental shelves to pelagic
realm. The increased supply of the terrestrial materials canlower light transmission rate in seawater and possibly
impede photosynthesis. Because that the materials fromterrestrial and atmospheric origin can multifacetedly andsignificantly impact on marine ecosystem and diversity,
integrated research must be pursued for elucidation suchas intensive observation in coastal regions, observation inextensive areas including pelagic realm, and laboratory
culture and numerical modeling.
It is important to grasp the overall trend of the influenceby clarifying the taxa present and populations in the areas
such as river mouths and coastal erosions and studying
their relationships with quantity and quality of terrigenous

delivery of trace metals such as iron due to continental ice
sheet melting has recently been pointed out. Therefore, thematerials transported from land impact on particularly
bacteria and phytoplankton with high bio-diversity andbio-volume in the coastal regions. Moreover, zooplankton,
which consumes the biotas described above, and those at
higher trophic levels can also possibly be affected. Whileit has been pointed out that terrigenous materials once
deposited on the sea floors in the coastal regions havebeen transported from the continental shelves to pelagic
realm and utilized for biological production, quantitative
estimates have not been elucidated due to the complexity
in the concerning biophysicochemical processes.
The influence by the material transport throughatmosphere on ecosystem along with global warming will
also likely be changed. While anthropogenic pollutants
that are emitted in the mid-low latitudes, for example, canbe transported to the Arctic Circle throughatmosphere（ AMAP, 2009） , the presence or absence of
sea-ice can possibly alter processes such as the supply
process of these pollutants to marine biota and thealteration process by photoreaction in seawater. It is
possible that the contribution by nutrients throughatmosphere will increase. In general iron that is a
micronutrients tends to be deficient in marine regions
away from terrestrial regions, but they are supplied via
atmosphere to the sea surface layer of the regions awayfrom lands. It is possible to have an increased supply ofiron attributing to the increases in exposed land area andstorm activity that are caused by loss of snow and ice dueto the global warming.
b. Future research (see Figure 35)
It is urgent to pursue the researches that can elucidate
the influence on marine ecosystem by the materials from85

experimental additions of the substance from atmosphereand land and thereby lead into future predictions.
Furthermore, because that the alterations in supply rates
and quality of the substances from atmospheric andterrestrial origin depend on the changes in remote areas,
integrated interdisciplinary research such as oceanography,
meteorology, glaciology, and ecology is needed to assess
the impact on ecosystem.

matter. Furthermore, in order to elucidate the impact on
ecosystem via remineralization of nutrients bydecomposition of terrigenous matter and via acidification,
it is important to determine the areas of significant impact,
conduct time-series biophysicochemical measurements,
and understand material cycles and seasonality of
biological species and populations.
Furthermore, it is also important to study the responses
by microbials and phytoplankton by conducting

Q2: How do the biotas of the Arctic Ocean transport substances and alter their quality?
and thus significantly participates in the material cycling
through denitrification in the anaerobic environments. In
the regions of deep basins, the following differences areobserved for vertical material transport via biotas. In theregions of the Amundsen and Nansen basins, where
diatom production is relatively high due to nutrients
supplied together with Siberian river waters, diatom
fluxes towards sea floor have been increasing due to the
reduction in sea-ice cover and becoming an important dietfor benthos (Boetius et al., 2013).
The primary production of the phytoplankton mainly
consisting of picoplankton size in the Canada basin, whichis under the influence of the anticyclonic Beaufort Gyre,is recognized, On the other hand, most of the particulateorganic matter produced in the surface layer isdecomposed in the subsurface layer and little would reachthe deep layers. This is because that particulate organic
matter, such as diatoms and coccolithophores, which playa role as sinking ballast, and zooplankton which consumes
the phytoplankton, is scarce （ Honjo et al., 2010） .
However, it is not well understood how the future
reduction in sea-ice cover would impact on materialtransport via ecosystem in the Canada basin. Because thatmany of the works on material cycles emphasized on theroles of primary producers such as phytoplankton and ice
algae (e.g., primary production and nutrient uptake rates),
the knowledge concerning the role of zooplankton, which
control material cycles, is significantly lacking(Wassmann 1998).

a. Importance of this research and state of the art
Ecosystem plays a role in altering and transporting
marine substances. It is considered that the substances
produced by low trophic levels are transported downward
towards deep layers and also transported horizontally by
own advection and by assimilation by higher trophic
levels. Today, our understanding of the relationships
between biotas and material transport throughout seasonsin each region of the Arctic Ocean is still inadequate. Thisis because that research has been pursued mainly on
biological production and vertical transport of low trophic
levels within limited seasons. Furthermore, ourknowledge concerning the material transport fromzooplankton to fishes and then to birds is limited to earlysummer. The transport roles of high trophic level
predators such as marine mammals and sea birds, which
migrate extensively, are also not well understood.
Predictions and opinions have not yet been formed
because of the fragmentary knowledge regarding therelationships between species and ecosystem diversity andmaterial transport in the Arctic Ocean. This is because that
we do not know how the ecosystem, which has beendeveloped through geologic time thus far, would respondto future various progressive environmental changes andhow the interactions between the biotas and marine
material cycles would be altered.
(1) Material transport via low trophic level ecosystem
The relationships between water mass environments
and species diversity of low trophic levels and material
cycles have been understood primarily in the continental
shelf regions such as coastal areas of the Chukchi Sea,
Beaufort Sea, Amundsen Gulf, and Laptev Sea where seaice cover is insignificant during summers (e.g., Bluhm etal., 2011; Wassmann, 2011). Carbon dioxide and nutrients,
which dissolve in seawater, are transformed into organic
matter mostly by photosynthesis. In the region ofcontinental shelf, a large amount of particulate organic
matter, which is produced by phytoplankton and ice algae,
supports the production activities of low level consumers
such as zooplankton and benthos as well as high level
consumers ranging from fishes to birds to marine
mammals. Because that most of the nitrate supplied to thephotic layer is taken up by biotas, this region tends to be
primarily under nitrogen control during summers(Tremblay and Gagnon, 2009). The part of phytozooplankton, which is not consumed by higher trophic
level consumers, is transported by zooplankton’s own
migration and gravitational sinking of body remains, fecalpellets, and aggregates and a part of which will be buried
in sediments. The microbial assemblage in the Arctic
Ocean demineralizes organic matter, which is supplied
from the water column and land, and recycles nutrients(2) Material transport by fishes and fowls
It is known that seafowls transport substantial amouontof various materials from the sea to breeding grounds withfeathers, feces, eggs, and dead bodies of chicks in the
Arctic Ocean （Michelutti et al., 2009）. However, thecontribution by fishes and fowls to material transport has
not yet been adequately elucidated for the detailed
processes and quantitative understanding. Furthermore, it
is known that various seafowls utilize the Arctic Ocean
during summers and many seafowls and ducks flock
together in polynyas during winters（Cooper et al., 2013）.
However, it is not well understood what roles does the
migration of seabirds and sea ducks play in the transportof materials in these periods.
b. Future research(1) Roles of low trophic level ecosystem in material cycles
It is important to consider process studies which areconcerned with the understanding of primary producers
dynamics, feeding of zooplankton, excretion andremineralization, and furthermore three-dimensional
relationships such as the pelagic-benthic coupling (Box 6),
which will be described in Q3 later. In order to accomplish
86

marine enviroenmental changes in the Arctic Ocean
would sensitively affect material cycles via microbial
assemblages. With all these matters in mind, thefollowings are the issues to work on in the future: (1) midlong term evaluation of the effects on microbial ecosystem
by climate change, and elucidation of the differencesamong different geographic areas; (2) the processes thatwill be further manifested in the future (e.g., elucidationof the effects on microbial ecosystem cuaused by weather
disturbance due to sea-ice disappearance); and (3)analytical diversification of tempospatial changes byintroduction of molecular biological methods whose
technological innovation is rapidly progressing in recent
years.

this, it is necessary to conduct diversified field research bycombining the following items during the periods
including springs when phytoplankton productivity
increases and winters which serve as preparatory periods
for production: (1) sampling from icebreaker research
vessels; (2) on board culture experiments of zooplankton;and (3) mooring experiments with observational
instrumentation such as sediment traps. Furthermore, it isalso necessary to conduct joint research with satellite
observation and ecosystem modeling, both of which cancover wide geographic areas at once. Japan has been
contributing in the field observations primarily in the
Pacific side of the Arctic Ocean employing R/V Mirai,
Japan Agency for Marine-Earth Science and Technology,
and T/V Oshoro-maru, Hokkaido University, thus far.
However, these vessels are not icebreakers and thus theirfield works are limited only to open waters and summer
seasons. While field works in sea-ice areas employing
icebrakers have been conducted by collaborating withinternational institutions such as the Institute of Ocean
Sciences （IOS）, it is also necessary in the future toactively pursue cooperative observations withinternational institutions such as the IOS and Arctic Net.

(3) Material transport to ocean-land ecosystem by highlevel predators including salmonoid fishes and seafowls
Movements of seafowls and marine mammals can betracked by biologging method and the areas for feather
molting and frequent visit can be characterized. Likewise,
the amounts for molting and excretion are estimated andtheir supply rates of organic matter can be estimated.
Furthermore, by estimating tempospatial changes of
predation amounts the roles for material cycles played byseafowls and marine mammals can be evaluated. The
distributional areas of salmonoid fishes are expected toextend into the Arctic Ocean due to the acceleration of the
global warming （e.g. Kaeriyama, 2008; Kaeriyama et al.,2014; Abdul-Aziz et al., 2011）. While it is well known
that salmonoid fishes transport significant amount ofmarine-derived nutrients （MDN） into land ecosystem(Kaeriyama et al., 2012; Koshino et al., 2013), theelucidation of the MDN transport mechanisms bysalmonoid fishes to the surrounding marine areas and land
ecosystem, due to the environmental changes of the Arctic
Ocean, is warranted (Figure 35).

(2) Material cycle mechanisms driven by microbials
For mechanism elucidation of material cycles that are
driven by microbial assemblages, it is important toquantitatively describe spatiotemporal changes of various
parameters of microbials and to characterize their factors.
Recent vigorous research development by many countries
has led the understanding that various parameters of
microbials in the Arctic Ocean are tempospatiallyextensively changing in response to diversified organiccarbon sources (primary production, fresh water,
sediments) and physical environments (distribution ofwatermass, temperature) （Uchimiya et al., 2011）. These
facts suggest that the impact by the rapidly progressing

Q3: How are the food chain and changes in ecosystem and biodiversity related in the Arctic
Ocean?
microbials is further less. While a lot of knowledge on
zooplankton has been accumulated in the Atlantic side of
the Arctic Ocean, such reports in the Pacific side arelimited. There are reports documenting that temperate
zooplankton extended distribution (Matsuno et al., 2011)and began reproduction (Buchholz et al., 2012) within the
Arctic Circles. However, it is not known how theseoccurrences affect the whole zooplankton community.

a. The importance of this research and state of the art
There are several species that extended theirdistributions to the north due to the global warming andsea-ice reduction. Primary production tends to increase
due to the improvement of light environment （ Pabi et al.,2008） . One prediction states that when sea-ice is reduced
the main food chain would change from surface(production)-benthos (consumption) ecosystem to surface(production)-surface (consumption) ecosystem, which iscalled “pelagic-pelagic coupling” (Box 6). As a result of
this, there is a concern over the influence on biological
species diversity. The consequence of the influence would
impact land ecosystem via the material transport to landby seafowls and via the influence on polar bears.

(2) The formation of biological hotspots including low
to high trophic level biotas
There are places, which are called “biological hotspots”(Box 7), where biological production is high and energy
flow to higher trophic level predators is significantly high.
Clear understanding is lacking in the Arctic Ocean
concerning their loci and dynamics including their
spatiotemporal scales. It is not known how the followingchanges would alter species diversity via the changes infood chain in the biological hotspots. The changes
include: (1) migration of temperate species including
whales; (2) biological pump (the process which transports
the organic matter produced by phytoplankton in thesurface layer to benthos and biotas in deep layers)
essential for surface (production)-benthos (consumption)(1) Distribution, species composition, and productionof microbials and planktons
The changes in seasonal and spatial distribution andspecies composition of phytoplankton and microbials
would affect not only their own species diversities but also
the species diversity of consumers as well. Biologicalproduction under sea-ice cannot be ignored during winterand spring in the Arctic Ocean, but studies in theseseasons are meager and the information concerning
87

well as by mooring systems in reference to the pastoccupied stations.

ecosystem; and (3) biomass and distribution of large
fishes. There are concerns about pollutions due toatmosphere and river transportations and oil fielddevelopment （ Mallory & Braune 2012） and impacts due
to introduced species carried by transport boats.

(2) Biological hotspots and the elucidation offormation factors
The relationships among supply rates of nutrients,
biological production, consumption, food chain length,
and species composition (species diversity) will be studied
by grasping biological hotspots through distribution andpopulation density of each of the trophic levels ofplankton to higher trophic biotas (fishes, fowls, mammals)
and benthos. The formation factors for biological hotspots
must be elucidated by pursuing habitat modeling
employing physical oceanographic conditions as
independent parameters and ecosystem modeling
employing food web data. Regarding the salmonoid fishes,
which can become important fisheries resources,
distribution and their changes will be studied based on
environmental carrying capacity, growth, population
dynamics, and feeding nutrition ecosystem. Based onthese it is necessary to comprehensively understand theformation mechanisms of the biological hotspots.
Therefore, predictions for distribution change of eachof the species based on future marine environmental
predictions will be made employing habitat models.
Moreover, predictions will be further made by considering
migrations of temperate taxa by the global warming andtransportation, bottom up and top down effects due to
distribution expansions of prey biotas and large-sizedwhales, artificial hatching and stocking for salmonoid
fishes, and inter-species relationships such as potential
influence of pollutants. Distributions of benthos, seafowls,
and marine mammals will be studied by conducting
sampling from vessels and visual observations. Tracking
methods with mounting type small sized apparatus will
also be employed for seafowls and marine mammals.
Food web will be studied based on the distribution ofpreys (e.g., viewing of specimens, stable isotopic ratios,
fatty acid composition). Pollutant measurements of
sediments and biotas will be conducted as one of themonitoring items for the anthropogenic effects.

b. Future research
It is necessary to focus on the biological hotspots
concerning how the global warming and sea-ice reduction
would impact on biological species diversity via low levelproduction and food chain. It is also necessary to carry out
studies concerning distribution change of biotas including
the seasons when sea-ice is present (winter, spring), which
will lead into more accurate grasp of state of the art andfuture predictions.
(1) Changes in water mass structure and microbial
and zooplankton assemblages and elucidation of
production processes
It is necessary to elucidate the mechanisms how the
global warming and sea-ice reduction would affect low
trophic level production scheme and diversity including
microbials. The elucidation can be achieved by pursuing
the process researches concerning: (1) timing of sea-ice
melt, (2) phytoplankton bloom (the state at whichassemblages would at once reproduce and increase) under
sea-ice and ice margin and grazing by zooplankton, and(3) reproduction by zooplankton and growth timing.
In order to accomplish this, we ought to elucidate therelationships between sea-ice change and phytoplankton
assemblages by studying changes in distribution,
composition, size, and dominant taxa of phytoplankton
including ice algae, and by utilizing the output by Theme
3. The changes in zooplankton diversity, grazing,
reproduction and growth timing can be explained byseasonal and spatial changes in production, size, andcomposition of phytoplankton as well as by transport of
the Pacific taxa. The relationships are elucidated between
seasonal and spatial changes of the plankton assemblages
and composition, mode, sinking flux of biogenic sinking
particles. Samplings throughout the year including
underneath sea-ice should be conducted on icebreakers as

Q4: What are the impacts on the ecosystem and biodiversity in the Arctic Ocean by ocean
acidification and denitrification?
significantly affect ecosystem and diversity in the Arctic
Ocean.
On the other hand, due to the CO2 emmission by theanthropogenic activity the following processes have been
globally progresssing: (1) increase in CO2 concentrations
in seawater; (2) increase in hydrogen ion concentrations(acidification in the narrow sence); and (3) decrease in thesaturation degree of calcium carbonate（Orr et al., 2005）.
These are collectively called as “problems in ocean
acidification” and they have been discussed. There is apossibility that ocean acidification would give some kindof effect on almost all the marine biotas, regeneration, andgrowth. However, adequate research has not yet been
conducted about the effects by ocean acidification on thebiotas in the Arctic Ocean and thus this has beenrecognized as an urgent task (AMAP, 2013).

a. Importance of this research and state of the art (seeFigure 35)
It is no exaggeration to say that all the production ofmarine biotas is supported by phytoplankton in the surface
layer with exceptions in specific areas. In addition to lightand temperature, the deficiency of nitrogen nutrients is alimiting factor for production in the Arctic Ocean. The
supply of nitrogen nutrients will become a further
important factor for the future biological production of the
Arctic Ocean since it is considered that light andtemperature conditions will be improved due to the global
warming and sea-ice melting. The following two
processes determine nitrogen supply rates: (1)denitrification process which removes nitrogen nutrientson the continental shelves; and (2) nutrient supply processfrom subsurface layers due to vertical mixing. It is
possible that the changes in these processes would

88

Box 6 The pelagic-benthic coupling
Large-sized diatoms begin blooming as soon as light environment becomes prefereble in theearly spring of the specific years with late sea-ice retreatment in the sea-ice margin areas, whenadequate solar radiaton is available, of the southeastern and northern Bering Sea. Large
zooplankton feed on the daitoms but grow weakly since seawater temperature has not yet risen
adequately and thus the large-sized daitoms, which were not consumed, sink. This process
supports abundant lives of bethos and further contributes in the increased energy flow towards
benthic food chain represented by large predatory fishes such as flounders and sculpins. On theother hand, large-sized diatoms do not bloom in the warm years when sea-ice retreats early whensolar radiation is still weak and the surface layer is mixed by winter seasonal winds. Small-sized
diatoms bloom when stratification begins as season goes further when seawater temperature rises.
Small zooplankton, which feed on these diatoms, actively grows at this time since the seawatertemperature has already risen. Therefore, most of the diatoms are grazed more or less completely.
The increased small zooplankton is directly consumed by surface dwelling fishes. Likewise, there
is a hypothesis explaining that the surface production would flow into the benthic food chain when
sea-ice is abundant during the cold interval and the surface production would flow into the foodchain in the surface layer when sea-ice is reduced during the warm interval (e.g., Grebmeier et al.,2006, Figure 36).

Figure 36: The change from the pelagic-benthic coupled ecosystem to thepelagic-pelagic ecosystem,pelagic ecosystem.

Box 7 Biological hotspots
Biological hotspots represent the loci where low trophic level biological production is highcompared to the adjacent areas, benthos is also abundant, and plentiful seabirds and marine
mammals dwell and/or are spotted with their high flocking concentrations. The low trophic level
organisms stated above are represented by zooplankton which plays an important role since ittransfers substances to higher trophic organisms by feeding on phytoplankton and ice algae which
are primary producers in the polar oceans. Furthermore, because that the productivity of these low
trophic level organisms is high in the water column, generally benthos is also abundant in theregions compared to the surrounding areas. The results of research thus far suggest the following
areas can be designated as biological hotspots: North Water polynya of the northern Baffin Bay andCape Bathurst polynya of the Amundsen Gulf.

89performed in the low-mid latitudes. However, the Arctic
Ocean tends to be readily affected because that the Arctic
Ocean by nature has low ability to alleviate acidification.
Furthermore, it is anticipated to witness other stresses
simultaneously due to water temperature rise and theimmigration of mid-low latitude biotas caused by watertemperature rise.

(1) Effects by stratification
The biological assemblage that supports high biologicalproduction is phytoplankton which receives adequately
supplied nutrients from deep layers due to upwelling andwinter vertical mixing. It is said that phytoplankton has
been maintaining characteristic ecosystem for a long timethus far by being composed of large sized taxa (diatoms)
and adapting fertile marine environments. The global
warming and desalination processes due to fresh watersupply from land and sea-ice melting playphysicochemical roles and they would cause marine
stratification and prevent nutrient supply by upwellingfrom deep layers to surface layer. The stratification, which
reduces nutrient supply from deep layers, would decrease
photosynthesis (primary production) of phytoplankton
distributed in the surface layer and thus would
biologically impact on instability of the ecosystem. This
would, at the same time, cause species replacement fromlarge-sized phytoplankton (diatoms) to small-sized algae(coccolithophores and parmales), which enable toreproduce in oligotrophic environments.
Furthermore, it is inferred that the stratification of thesurface layer due to the global warming would lead into ahighly stressed situation by high light intensity to thephytoplankton community distributed in the mixed layer
due to the reduction in surface mixed layer thickness.
While the knowledge is meager concerning thephotoprotection mechanisms of the phytoplankton
distributed in the polar regions, the biological effects bystratification would appear more significantly in the ploar
and sub-ploar regions.

b. Future research
The understanding of the current status ofphytoplankton and zooplankton biomass and species
composition in the surface layer of the oceans has been
usual practice for ecosystem research and many scientists
published their contributions thus far. However, most of
the works are concerned with large-sized diatoms andcopepods and thus little knowledge has been accumulatedon coccolithophores, planktic foraminifers and pteropods
that are concerned about being affected by theacidification. For elucidation of the diversity
characteristics of the polar biotas it is significant tosufficiently understand the distribution dynamics of
coccolithophores and planktic foraminiferes andpteropods, which are zooplankton feeding on particulatematter. Such an understanding will be achieved by longterm monitoring in the areas of serious influence under the
expectation that phytoplankton size will be reduced due tothe reduction in nutrient supply from the subsurface to thesurface layer caused by the future stratification.
Furthermore, it is considered that phytoplankton
distributed in the surface mixed layer will be exposed tohigh light intensity for a long time due to the reduction in
the thickness of the surface mixed layer caused bystratification. It can be anticipated that the plankton
adapted to low light thus far in the Polar Regions would
be faced with an increased stress due to high light intensity.
Therefore, research on light protection mechanisms is alsoneeded together with direct acidification experiments for
phytoplankton production.
While the current denitrification rates have been
estimated in the Chukchi Sea and Bering Sea, thedenitrification rates are not understood in the vast areas of
the continental shelf on the Siberian side. Furthermore,
there has been no quantitative estimate of how do themicrobials, which perform denitrification, respond to the
future warming and the increase in organic matter flux
originated from terrigenous and marine biotas in the
Arctic Ocean. For example, it has been known that thechanges in denitrification rate along with seawatertemperature rise are different depending on the microbial
taxa. Integrated works of the following items withelucidation of seasonal and inter-annual changes would
benefit the predictions of future changes in primary
production in the Arctic Ocean: installation of sea floor
monitoring platforms in each of the areas, changes inorganic matter flux and temperature, redox state,
denitrification rate, and sampling of microbials. It is also
necessary to assess the influence on marine ecosystem anddiversity by adding the changes of denitrification rate innumerical model simulations.
Furthermore, the experimental studies for the effects on
marine biotas by future acidification have been progressedin the mid-low latitudes, but the experimental studies forthe effects on phytoplankton, zooplankton and higher
trophic level ecosystem are extremely rare in the Arctic
Ocean. Prediction experiments in the laboratory have noteven been performed concerning most of the biological(2) Effects due to denitrification
Nitrogen deficiency is especially apparent in theregions of the Pacific Ocean side. This stems from socalled denitrification process, which removes nitrogenfrom the oceans. The process is a microbial metabolic
activity that actively alters nitrate and nitrite into the inert
gas. The denitrification in these regions plays a significant
role in the nitrogen cycle of the world oceans. It is possiblethat marine primary production would be limited by theincreased removal of nitrogen due to the denitrificationthat is attributed to the increases in water temperature andorganic matter flux to benthos. However, quantitativeknowledge and elucidation of the effects by denitrification
are meager.
(3) Effects due to ocean acidification
There is a concern that the decrease in saturation degreeof calcium carbonate due to the ocean acidification would
negatively impact on, for example, coccolithophores
which represent phytoplankton, planktic foraminifers
which represent zooplankton, pteropods, and shelledmolluscas by reducing their ability for calcium carbonate
shell and/or skeleton formation. They are important biotas
also in the ecosystems of the Arctic Ocean and thesubarctic region. The concern is also the effects on higher
trophic level biotas, which predate the above listed biota,
such as fowls and mammals. It has been known bylaboratory cultures and in situ experiments that the ocean
acidification works on the biotas that do not form calcium
carbonateshellseitheradvantageouslyordisadvantageously depending on species. However, theeffects by the ocean acidification is not understood in theecosystem of the Arctic Ocean because that ourknowledge has mostly been derived from the works
90

taxa, while only limited studies are going on regarding
limited areas, biological taxa, and assemblages. Vast
continental shelf areas exist in the Arctic Ocean andbenthos plays important roles in ecosystem. Thus, it isnecessary to study the effects by the ocean acidification
on phytoplankton, zooplankton, shelled molluscas, anddiversified benthos.
In order to accomplish these tasks it is warranted toproceed with the studies concerning biotas dwelling in thediversified areas and the reality of acidification of the
Arctic Circle, with and the experiments for acidification
shift by laboratory experiments and in situ ventilation of
CO2 flow employing key species. It is essential to pursue
international cooperative projects together with thenations facing the Arctic Ocean. Because that theacidification in the Arctic Ocean has been reaching theserious state first ahead of other oceans, the studies in the
Arctic will be able to offer important information for
future predictions of the impact by the acidification inother oceanic areas by elucidating the responses of
ecosystem and diversity to be understood with long termmonitoring. It is considered that the knowledge obtainedin Japan regarding ecosystem prediction models, plankton,
and ecosystem can contribute significantly to theassessment research on the changes in the Arctic
ecosystem and diversity in response to the ocean
acidification.

91

Chapter 7: Broad and important subjects on the Arctic environment
Important environmental research that is not includedin the focus of the previous two areas are also underway
for the Arctic. We selected activities which werehighlighted as research themes by the JCAR community.

Following advances in research, this work will potentiallyprovide further information relating to the former two
focal points. In addition, it includes the research areas that
describe the basic information on the focal points.

Theme 10: Geospace environment
Abstract

may contribute to driving the global scale atmosphericcirculation. However, the full extent of such changes on a
global scale is still unknown. As one of the important
information infrastructure businesses that support thehuman society, it is necessary to monitor the polar upper
atmosphere in order to provide effective, reliable
detection and prediction of ionospheric disturbancephenomenon. It is expected that in the next few years,
geospace exploration, including the middle/upper
atmosphere, will be achieved using new satellite/rocket
observations and large atmospheric radar observations. In
conjunction with these enhanced observations, there is aneed to develop a research framework to evaluate andpredict the influence of geospace on the upper atmosphereand lower atmosphere. Questions about the impact of thegeospace environment on the Arctic environment and theconnection between the geospace and Arctic
environments are summarized as follows:
Q1: What are the effects of geospace on the upper
atmosphere and lower atmosphere?
Q2: What are the effects of the upper atmosphere on thelower/middle atmosphere?
Q3: What are the effects of the lower/middle
atmosphere change on the upper atmosphere?
Q4: How important is the energy flow from the polar
region into the middle/low latitudes through theupper atmosphere?

Due to the precipitation of charged particles and the
propagation of electromagnetic waves from geospace(space around the Earth that is part of the active region forhumans), it has been noted that in recent years the upperand lower atmosphere of the Arctic region is subject tochange. In particular, minor constituent variations in the
middle/upper atmosphere and its impact on the ozone
concentration and stratosphere-troposphere coupling suchas the downward propagation of the Arctic Oscillation —effect of the upper atmosphere on the lower atmosphereattracted the interest in the recent. It has also become clearthat the atmospheric waves excited in the lower
atmosphere have a great influence on the thermal anddynamical structure of the middle/upper atmosphere. In
addition, the results also suggest a significant increase in
the cooling of the middle/upper atmosphere withincreasing greenhouse gases. It is believed that
understanding the various coupling process between thelower atmosphere and the upper atmosphere is importantin order to appreciate the full extent of the Arctic
environment. However, little progress has been made witha quantitative impact assessment.
Electromagnetic and particle energies entering from theSolar wind and magnetosphere to the polar upper
atmosphere cause fluctuations in the upper atmosphere at
the low/middle latitudes (including large-scale
fluctuations such as magnetic storms). In addition,
atmospheric waves generated from the lower atmosphere

Introduction
experiences short-term and long-term variations due tovarious factors, such as energy and momentum transport
by atmospheric waves41 excited in the lower atmosphereand an increase in greenhouse gases. Research on"coupling processes between the lower and upper
atmosphere" to understand these effects from above andbelow has become a priority in the Arctic; this also applies
to research that examines interactions across the wholeatmosphere. Various modulations in solar activity, such as
the absence of sunspots for more than one year, haverecently been reported. There is concern that this might
affect the Arctic environment through coupling processes
between the upper and lower atmosphere. In order toaddress these issues, cross-cutting interdisciplinary
research is required.
In addition to space utilization by human society (asGeospace is a term used to describe the space aroundthe Earth that falls within the zone of human activity; thisincludes the area within which we find many satellites, theInternational Space Station, and the flight paths ofplanetary exploration spacecraft. The geospace has been
distinguished from the distant universe that lies beyond
the reach of humans, and its researches and observations
have been made to better understand its environment.
Recent studies have revealed that changes in solar
activity and in the space around the Earth affect the global
environment. In particular, since the polar region issusceptible to solar winds and to interplanetary magnetic
fields40, and is affected by various types of energy input
from above, detailed understanding of physical andchemical processes is required. It is also becoming
apparent that the upper atmosphere particularly
40Interplanetary magnetic field: The solar magnetic field carried by the solar wind to interplanetary space (i.e., space where planetary orbits in thesolar system exist). Because of the rotation of the sun, the magnetic field lines of the interplanetary magnetic field are spread in a spiral form from thesun.
41
Atmospheric waves: Waves in the atmosphere generated by a variety of atmospheric disturbances. There are more localized atmospheric gravity
waves and global-scale atmospheric tides and planetary waves, whose restoring force is generated by atmospheric density stratification with gravity
and by the conservation of angular momentum due to the rotation of the Earth, respectively. Atmospheric waves generated in the lower atmosphere
propagate upward and release energy and momentum in the mesosphere and thermosphere due to their breaking caused by amplification with altitude;
this drives the meridional circulation and zonal wind change in the upper part of the middle atmosphere.

92

Figure 37: Relationship between four key questions of theme 10.

In this section, the influence of the geospaceenvironment on the Arctic environment and theconnections between these (in other words, coupling
processes) is described separately through four key
questions. First, in "Q1: What are the effects of geospaceon the upper and lower atmosphere?" with the keyword"space weather research", the impact of solar activity andchanges in the space around the Earth on the global
environment are mainly described. Next, in "Q2: What are
the effects of the upper atmosphere on the lower/middle
atmosphere?", we specifically describe research into
"lower and upper atmospheric coupling processes",
including the downward propagation of atmosphericminor constituents. In "Q3: What are the effects oflower/middle atmosphere change on the upper
atmosphere?", we summarize impacts from the lower tothe upper atmosphere, including the cooling of the
middle/upper atmosphere coincident with global warming.
Finally, in "Q4: How important is energy flow from thepolar region into the middle/low latitudes through theupper atmosphere?", the importance of the study oflatitudinal coupling is discussed.

represented by positioning satellites), study of thegeospace environment has also been utilized to improve
the accuracy of space weather42 forecasts required for theoperation of satellites. Thus, in the Arctic, study of thegeospace environment is becoming important also as apractical science to reduce the risk to social infrastructure(communications, power supply, and positioning). In
particular, in Arctic countries (e.g., Norway), various
space weather phenomena resulting from changes in thegeospace environment have been recognized as a social
concern. Specific social impacts are described in Q4 of
Theme 7, "Effects of the Arctic environment on humansociety."
Many of these solar-terrestrial studies have been led by
Japan as international collaborative research projects.
Enhancement of geospace exploration can be expected
within the next few years, such as through newsatellite/rocket and large radar observations, including the
exploration in the middle/upper atmosphere; this is
expected to occur within the framework of international
cooperation initiated by Japan. In order not to miss thisopportunity, there is a need to develop a research system
to assess and predict the influence of the geospace on theupper and lower atmosphere and their interaction.

Q1: What are the effects of the geospace on the upper and lower atmospheres?
decrease in ozone in the polar mesosphere and upper
stratosphere has been noted (e.g., Jackman et al., 2001). In
recent years, it has also been suggested that mesosphericozone is depleted by electron precipitation from theradiation belt (Rozanov et al., 2005). However,quantitative evaluation of the impact of these processes on
the middle atmosphere has not been sufficient. Since air
shower of these energetic particles causes radiation

a. Importance and current status of research
It is known that energetic particles emitted from the sun
and galaxies and found in the radiation belt that aretrapped by the geomagnetic field precipitate into the upper
atmosphere; these can cause such effects as ionization in
the altitude region below the mesosphere (Rishbeth andGarriott, 1969). For example, in the event of a large-scale
magnetic storm 43 and solar energetic particles (SEP), a
42

Space weather: Since the human activity area has extended into space, the space environment and its fluctuation phenomena have come to bereferred to as space weather, in a similar fashion to the terrestrial weather that affects human life. Electromagnetic fields, radiation belt particles, andcosmic rays are major elements of space weather. Energy associated with space weather disturbances enters the polar ionosphere along the Earth’s
magnetic field lines and affects the thermal structure and chemical composition of the upper atmosphere.
43
Geomagnetic storm: The largest disturbance phenomenon in the geospace caused by large-scale disturbances in the sun. It has also, as of recently,
been referred to as a geospace storm. During this phenomenon, a large current flows through the space around the Earth and the amount of cosmic
radiation increases. In addition, it has a significant impact on the Earth’s atmosphere, such as the ionosphere, thermosphere, etc., and energy input
from space to Earth increases rapidly.

93(the use of which has increased very notably in recent
years) and of aircraft navigation systems that rely on it. In
particular, “extreme space weather phenomena”, which
are less frequent but which occur on a large scale, areexpected to have very large impacts, even though there has
been limited observation of these so far and quantitativeevaluation is difficult.
Furthermore, various modulations of solar activity havebeen reported in recent years (e.g., Shiota et al., 2012). In
particular, the current situation is similar to the Maunder
Minimum 44 , with a longer-than-usual minimum period
and limited sunspot number increases even during the
maximum period. There is therefore speculation thatcooling of the Earth’s atmosphere, similar to that which
occurred during the Maunder Minimum, will take place.
On the other hand, because global cooling during theMaunder Minimum cannot be explained only by

exposure at flight altitudes, especially around the polar
region, prediction and impact assessment of this change isimportant for space weather research.
Although the energy input from the geospace into
Earth's atmosphere causes a variety of variations in thepolar upper atmosphere, understanding of these processes
is still insufficient (e.g., Gray et al., 2010). In highlatitudes, large currents flowing through the ionosphere,
along with auroral activity, generate an induced current on
the ground, causing failures in transmission line networks
and pipelines, etc. It has also been reported that
thermospheric air expansion due to rapid increase in solar
ultraviolet radiation caused attitude disturbances ofsatellites, with these ceasing operation. In addition,
disturbance phenomena in the ionosphere (e.g.,
ionospheric storms, plasma bubbles, etc.) significantly
affect the accuracy and reliability of satellite positioning

Figure 38: Solar-terrestrial region: (top)phenomena that occur in the region and(bottom)influenceof
geospace
disturbances on society. Both figures arecited from “Present and Future of theSociety of Geomagnetism and Earth,Planetary and Space Sciences” (SGEPSS,
January 2013).
----- Courtesy of K.Seki

44
Maunder Minimum: The period during which hardly any sun spots appeared over several decades in the second half of the 17th century. During thisperiod, while solar activity was distinctly weak, the Earth's atmosphere was believed to be colder. It has therefore been suggested that solar activity
affected the global climate.

94

the polar region, we need to build a model to evaluate
impacts on each altitude layer in response to inputs ofultraviolet radiation and energetic particles from thegeospace. Also, with regard to less frequent but largeamplitude phenomena called extreme space phenomena,
it is important to assess impact on the basis of past casestudies, and to reproduce and predict such phenomena
through physical modeling. Thus, as one of the important
information infrastructure businesses supporting humansociety, we consider it necessary to advance monitoring of
the polar upper atmosphere and research into ionosphericdisturbance phenomena, allowing for their effective andreliable detection and prediction in conjunction with theengineering community (such as communication andaeronautical engineering).
Japan is playing a leading role in international joint
research projects such as CAWSES-II (Climate And
Weather of the Sun Earth System, 2009 ~ 2013) and
VarSITI 45 (Variability of the Sun and Its Terrestrial
Impact, 2014 ~ 2018), promoted by researchers of sunearth system science, for example by producing project
leaders. In addition, Japan has international research
centers focused on sun earth system science, and is
deploying observation bases overseas, including in the
Arctic. Taking advantage of such Japanese superiority andin order to clarify the response of the Earth's atmosphereto changes in future solar activity, aggressive approaches
are expected from the solar-terrestrial science community.

fluctuations in the solar constant, several mechanisms inthe middle/upper atmosphere have been proposed as its
cause. However, quantitative verification of theseprocesses is still insufficient, both in terms of observationand modeling.
b. Future research
In order to evaluate the impact on the atmosphere(especially in the polar region) of energetic particles fromthe geospace, it is important to have precise observationsof the upper atmosphere and comparative observations of
the ionosphere and magnetosphere by radars,
spectrometers, and electromagnetic field measurement
equipment on board satellites and from the ground. In
particular, it will be essential to effectively utilize thegeospace exploration satellite (ERG) scheduled to belaunched in the next few years, as well as new large
network observations and large observation bases (such as
the next generation incoherent scatter radar program(EISCAT_3D) scheduled to be installed in North Europe
by the international joint framework). In addition, there isalso a need to build a system to advance research throughclose collaboration between the sun-heliosphere,
geospace science community and the upper/middle
atmospheric science community.
In order to quantitatively evaluate and predict changes
in the impact of electromagnetic waves and energetic
particles from the sun on the middle/upper atmosphere in

Q2: What are the effects of the upper atmosphere on the lower/middle atmosphere?
upper atmosphere influence atmospheric circulation in thestratosphere and further in the troposphere. Energetic
particle precipitation and variations in solar ultraviolet
radiation are closely related to solar activity. Quantitativeevaluation of the degree of influence the solar activity has
on atmospheric general circulation46 in the stratosphereand troposphere through changes in atmospheric minor
constituents is thus also a future challenge.
On the other hand, it is also becoming clear thatplanetary waves excited in the troposphere propagate to
the stratosphere, changing stratospheric circulation, whichfurther affects tropospheric general circulation (Plumband Semeniuk, 2003). However, it is not well understood
what influence variations in the mesosphere andthermosphere, due to various waves of tropospheric origin,
have on the troposphere through vertical coupling
processes. In addition, there is a need for future research
into the types of effects that stratospheric ozone variations
due to energetic particle precipitation have on the
troposphere, through changes in stratospheric generalcirculation.
In addition, there is also a possibility that a decrease instratospheric ozone will affect the lives of Arctic residents
through an increase in the surface ultraviolet dose. Sinceozone depletion is closely related to planetary wave
activity in the stratosphere, it is an issue that must be
considered within the framework of tropospherestratosphere coupling processes. For example, althougha. Importance and current status of research
The basic nature of the Earth's atmosphere, in which thelower atmosphere affects the upper atmosphere, originatesfrom the stratified structure of the Earth's atmosphere, i.e.,decreasing density with altitude. On the other hand, inrecent years there has been more attention focused on
influence from the upper to the lower atmosphere, such as
through stratosphere-troposphere coupling represented by
downward propagation of the Arctic Oscillation (e.g.,
Baldwin and Dunkerton, 1999). The polar region, in
which there is energy input into the ionosphere andthermosphere associated with solar activity, is considered
to be subject to effects from the upper atmosphere on thelower/middle atmosphere. In order to understand andpredict medium- and long-term fluctuations of the polar
lower atmosphere, it is therefore particularly important tounderstand mechanisms of vertical coupling processes
through cumulative observations of influences from theupper to the lower atmosphere, combining these withstudies using numerical models.
It is becoming clearer that variations in atmosphericminor constituents (e.g., nitric oxide (NO)) due toprecipitation of energetic particles and to changes in solar
ultraviolet radiation propagate downward and affectozone concentrations in the stratosphere (e.g., Randall etal., 2007). However, there has as yet been no quantitative
assessment of the extent to which changes in stratosphericozone concentrations originating from variations in the
45

VarSITI: Variability of the Sun and Its Terrestrial Impact (VarSITI) is an international collaborative research program in solar-terrestrial science
spanning the five-year period 2014-2018; it is organized by the international organization SCOSTEP (Scientific Committee on Solar-Terrestrial
Physics) under the umbrella of ICSU (International Council for Science). Related website: http://www.stelab.nagoya-u.ac.jp/varsiti/.
46
Atmospheric general circulation: Atmospheric general circulation is global-scale atmospheric flow. This circulation occurs in order to eliminate thetemperature difference between equatorial and polar regions created by differences in incident solar radiation energy. In addition, global-scale
circulation is generated also due to the influence of vertically-propagating atmospheric waves in the middle/upper atmosphere.

95

Figure 39. Impact of the sun on the Earth’s ionosphere and atmosphere. The figure is cited and partly
modified from “Present and Future of the Society of Geomagnetism and Earth, Planetary and Space
Sciences” (SGEPSS, January 2013).

atmosphere on the lower/middle atmosphere, it isimportant to have a quantitative understanding using
numerical models. In addition, to understand to what
altitude and to what extent the upper atmosphere affects
the lower/middle atmosphere, we need overall verification
by various models covering different altitude regions,
including models that do not include the thermosphere andionosphere, models that do not include the mesosphereand above, or on the contrary, models that do contain thethermosphere and ionosphere. Globally, there has been
upward extension of model top height and models that
include the altitude region from the troposphere up to thethermosphere/ionosphere have been developed in Japan(GAIA model; Jin et al., 2011). In future, further
improvement of model accuracy will be important. Also,in order to consider photochemical processes (including
ozone depletion), it will be necessary to develop a model
including photochemical reaction processes in the altitude
region from the troposphere up to the mesosphere andthermosphere, and to improve its accuracy. The solarterrestrial science research community in Japan has a greatinterest in coupling processes between the lower andupper atmospheres, and is actively developing theobservational and modeling studies described above.

the ozone hole formed in the Arctic during the spring of
2011, whether similar ozone depletion will occur in future
cannot be predicted well at present (e.g., Manney et al., 2011).
b. Future research
To examine variations in minor atmosphericconstituents associated with energetic particle
precipitation in high latitudes, it is important to makeobservations using large atmospheric radar and groundbased network observations of atmospheric composition,
temperature, and wind in the middle/upper atmosphere,
using various measuring instruments at high latitudes. In
particular, precise observations using large observationequipment (such as the EISCAT_3D radar) and expansionof ground-based observation networks for examining
global atmospheric fluctuations are essential to enable
quantitative understanding. Furthermore, we need to
combine these ground-based observations with satellite
observations of the neutral and ionized atmosphere ataltitudes from the middle atmosphere to the thermosphereand ionosphere, in order to reduce assumptions behind
individual observation instruments and to reach anunderstanding of their nature.
In order to investigate the effect of the upper

Q3: What are the effects of lower/middle atmosphere change on the upper atmosphere?
a. Importance and current status of research
While global warming due to an increase in greenhousegases has occurred in the troposphere, ground-based andsatellite observations and modeling studies have indicatedprogressive cooling in the middle/upper atmosphere (e.g.,
Roble and Dickinson, 1989). Cooling of the middle/upper
atmosphere coincident with global warming in the lower
atmosphere appears more pronounced in this altitude96

Figure 40: Relationship of the upper atmosphere with global warming and climate change (left: cited from “Present and Futureof the Society of Geomagnetism and Earth, Planetary and Space Sciences” (SGEPSS, January 2013)) and mesospheric clouds
photographed in Paris sky (right: http: //www.spaceweather.com/nlcs/gallery2009_page12.htm).

et al., 2012). Although these variations are thought to be
induced by global-scale variations of atmospheric waves,such as planetary waves and gravity waves, overall
understanding of these processes is still lacking. It has
therefore become necessary to utilize a new viewpoint,considering Earth's atmosphere holistically andconnecting all atmospheric regions, from the lower
atmosphere, which is the realm of meteorology, to theupper atmosphere. Such studies are expected to be able toallow, among other aspects, prediction of the occurrenceof stratospheric sudden warming, which may becomefrequent in the Arctic in future.
Furthermore, recent development of GPS networks has
made it clear that atmospheric waves excited by tsunamis
occurring after earthquakes, typhoons, and hurricanes, aretransmitted to the ionosphere and modulate plasma
density in the ionosphere (Tsugawa et al., 2011). This
result indicates that ground and sea-level changes canaffect the upper atmosphere, reflecting an image of a
dynamically-varying Earth and suggesting a new
possibility, i.e., that ionospheric research could develop asa disaster prevention science, for example, for predicting
tsunami arrival.

region because of low atmospheric density. For example,
an increase in water vapor in the vicinity of the mesopause,
associated with increasing methane, and cooling in the
middle/upper atmosphere due to an increase of carbon
dioxide have resulted in increase of the occurrence ofpolar mesospheric clouds in the Arctic and theirassociated specific radar echoes in the mesosphere (PMSE,
MSE), and in the equatorward expansion of the generation
region of mesospheric clouds (see Figure 40); the latterare thought to be an indicator of global warming in thelower atmosphere. It is thus possible to examine to what
extent changes in the middle/upper atmosphere due toglobal warming are occurring. However, since long-term
data for the middle/upper atmosphere is very limited, thestudy of inter-decadal variations has only just begun. In
particular, it is very important to carry out bipolar
comparative studies between the Arctic, which is an active
region of human activity, and the Antarctic, which differs,in order to understand and identify the process of coolingin the middle/upper atmosphere associated with global
warming.
Since 2000, sea level rise and surface warming haveincreased in the Arctic due to the amplification of Arctic
warming. If the AO index47 becomes negative, there is apossibility of enhancement of its spatial pattern, and in
winter, it is likely to lead to an increase in disturbances, as
represented by stratospheric sudden warming 48 (e.g.,Turner et al., 2007). It becomes clear from recent
observations and numerical simulations that a distinct
indicator of stratospheric sudden warming may be
emerging in the atmospheric circulation in the mesosphereand the lower thermosphere, prior to variations in thestratosphere. It has been observed that variations in the
middle atmosphere due to stratospheric sudden warming
modulate the atmospheric waves propagating from thelower atmosphere and cause fluctuations in thethermosphere and ionosphere at low latitudes (e.g., Chaub. Future research
The middle/upper atmosphere changes associated with
global warming have a global impact through changes inthe vertical profile of atmospheric temperature,
disturbances in the Arctic, and modulation of atmosphericwave propagation from the lower atmosphere. In this area
where long-term data acquisition has just begun, it is mostimportant to continue ground-based and satellite
observations and model calculations. In the Arctic, it isdesirable to enhance network observations longitudinally,
and it is essential to continue to operate observation sites
in Alaska, Canada, and northern Europe (whereobservation instruments are already installed), and to47
AO index: The AO index is obtained by projecting geopotential height anomalies in the Northern Hemisphere troposphere on specific days ormonths onto the first principal component vector obtained from principal component analysis of the geopotential height field in the troposphere (i.e.,
1000hPa and 500hPa) of the Northern Hemisphere (i.e., poleward of 20 °N). Positive and negative indices represent the strengthening and weakeningof Arctic low pressure regions, respectively. For more information, refer to URL:
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index.html.
48
Stratospheric sudden warming: The phenomenon in which temperature rises rapidly over a short period in the winter polar stratosphere. While itoccurs frequently in the Arctic, it rarely occurs in the Antarctic. The definition given by the World Meteorological Organization (WMO) refers to aphenomenon in which temperature rises more than 25 K within a week and zonal mean temperature at or above 10 hPa increases towards the poles
from 60 ° latitude.

97

significant to understand the characteristics of ionosphericdisturbances and to predict their occurrence, also becauseof implications for infrastructure, such as satellite
positioning and communication methods using radio
waves that propagate through the ionosphere.
In order to capture the variation in atmospheric generalcirculation and global-scale change, it is necessary to also
strengthen cooperation with observations in middle andlow latitudes and in the Antarctic. It is especially
important to continue ongoing cooperation with Syowa
Station in Antarctica, which has many observation
instruments such as the PANSY radar, lidar, and MF radar,
and with each Japanese observation site in the Arctic.
Research focusing on bipolar comparisons will be
important for understanding and identifying middle/upper
atmosphere cooling processes coincident with global
warming and its prediction.
Japan is planning and maintaining infrastructure (i.e.,observation bases and network observations) in order toadvance such studies, and is expected by the international
community to contribute to the development of research.

strengthen further cooperation with large observation
bases (such as the EISCAT_3D radar, the SuperDARN
radar, and AMISR). In particular, we should consider
cooperation with Russia where few observation points
presently exist. In addition, it is also important to further
enhance model calculations in middle/upper atmosphereresearch with limited observation methods.
With regard to future research directions, it is more
important than ever to understand various atmosphericwaves as an important process for linking atmosphericregions. We need to understand, on a global scale, howatmospheric waves excited in the lower atmosphere
propagate, where they dissipate to, and the characteristics
of turbulence considered to be generated by thedissipation of atmospheric waves and secondarygenerated atmospheric waves. In particular, turbulence inthe middle atmosphere is an important research issue,
since it can greatly affect the structure of the thermosphereabove it. Additional future issues to be resolved include
how atmospheric waves present in the whole atmospheremodulate the structure of ionospheric plasma and how
ionospheric disturbances are induced. It would be very

Q4: How important is the energy flow from the polar region into the middle/low latitudes
through the upper atmosphere?
a. Importance and current status of research
Energy inputs of plasma and electromagnetic field
fluctuations from the solar wind into the upper atmospherethrough the Earth's magnetosphere mainly occur in thepolar region, where Earth's magnetic field lines converge.
Inputs of plasma and electromagnetic energy heat andvary the upper atmosphere through the Joule heating andthe Lorentz force. Such dynamic variations propagate to
the middle/low latitudes as atmospheric waves. Changes

in atmospheric composition due to heating also spread
into the middle/low latitudes through material transport.
In addition, electromagnetic field fluctuations that haveentered the polar region are transferred to the low latitudes,
as geomagnetic pulsation trapped in the ionosphere and aselectric field fluctuations trapped between the ionosphereand the ground. Through these various processes,
electromagnetic energy that has entered the polar region
from the solar wind and the magnetosphere causes

Figure 41: Schematic diagram of energy input from the polar region to the middle/low latitudes through theupper atmosphere, and related phenomena.

98

along the three main meridians in Asia, Africa, andAmerica. Base observations from a large radar (such as
the EISCAT_3D), enabling observation of threedimensional structures with high time resolution, areespecially needed in the polar region, in order to observe
the complex spatial and temporal variations of the plasma
atmosphere. In addition, at ground-based multipoint
network observations along a meridian, simultaneous andmultipoint observations of electromagnetic field
fluctuations and neutral atmospheric variability at
multiple altitudes are needed; these can be obtained by
combining data from high sensitivity airglow cameras,
GNSS receivers, Fabry-Perot interferometers, meteor
radars, large HF radars, magnetometers, etc. Also,
because atmospheric tides and planetary waves have alongitudinal structure, it is important to expand
observation points longitudinally around the polar region.
It is essential to measure global-scale atmosphericcoupling in conjunction with these ground-based remotesensing observations, with direct satellite observations ofneutral atmosphere and plasma in the ionosphere, and withimaging observations from satellites with wide-areacoverage. The research community in Japan has much
experience of ground-based multipoint network
observations, base observations, and satellite observations,and should play a central role in promoting latitudinal
coupling research within a framework of international
cooperation, through maintenance and expansion of future
observations.
In terms of model development, under Japan’s initiative,
a whole atmosphere model that can be solved in aconsistent
way
from
the
groundtothethermosphere/ionosphere has been developed (e.g., Jin etal., 2011). However, it does not have a spatial resolutionthat can explicitly49 generate atmospheric gravity waves,which are an important driver of atmospheric generalcirculation. Furthermore, electrical coupling processes
with electromagnetic energy entering from the solar wind
and the magnetosphere are not yet sufficiently represented.
In future, it will be necessary to incorporate these physicalprocesses into the whole atmosphere model. In addition,
we must also consider developing a technique for data
assimilation in order to include the data of ground-based
and satellite observations into the model. Moreover, inorder to take advantage of the dense network of long-term
ground-based magnetic field observation data, it will benecessary to carry out a comparative study between
ground-based magnetic field observations and magnetic
field fluctuations simulated by a thermosphere-ionospheremodel.

fluctuations in the upper atmosphere in middle/low
latitudes. Typical examples are positive/negative-phase
ionospheric storms with unusual increase/decrease ofelectron density in the ionosphere, respectively, and theequatorial ionospheric instability induced by the intrusionof the electric field. These phenomena are importantbecause they have a significant impact on communication
between a satellite and the ground and on positioning
using GNSS satellites. However, it is difficult at present
to understand, through observations, the overall
propagation process of these energies and materials to
middle/low latitudes. In the model, it is also difficult tosolve electromagnetic field fluctuations and dynamic
fluctuations of the neutral atmosphere under the boundary
conditions at the model top and bottom (e.g., Schunk andNagy, 2000).
It has been noted that atmospheric waves generated in
the lower atmosphere drive global-scale meridional
circulation by dissipating and releasing momentum near
the mesopause. However, exact quantification of theireffects (i.e., parameterization) presents a challenge interms of improving the accuracy of future predictions. In
addition, it has become apparent from recent studies that
secondary waves generated by the momentum deposit andwaves that are not dissipated in the mesosphere propagate
into the thermosphere, causing global-scale variations in
the ionosphere (e.g., Vadas and Crowley, 2010). These
processes have been found to occur widely for various
waves, from gravity waves with a period of several hours,
to planetary waves with a period of several days.
Moreover, it is known that the effect of these processes,
having a driving source in the polar region, is graduallytransmitted to the middle/low latitudes. As also mentionedin Q3, recent observations have made it clear that theeffect of sudden warming which occurs in winter in the
Arctic stratosphere appears in the distant equatorial
ionosphere and in the Southern Hemisphere mesosphere,
as well as over the Arctic. Propagation of atmosphericwaves and associated momentum transport are considered
to be leading possible causes of these phenomena, and anumber of researchers are working on developing a morecomprehensive understanding of these mechanisms. In
addition, propagating ionospheric disturbances frequently
observed in the ionosphere are believed to be caused byatmospheric waves coming from the lower atmosphereand the auroral zone, and also by ionospheric plasma
instability dependent on electromagnetic field fluctuations.
There is also a need for research to isolate the two (e.g.,
Makela and Otsuka, 2012).
b. Future research
In order to understand latitudinal coupling in the upper
atmosphere, where neutral atmosphere changes andelectromagnetic field fluctuations are complexlyintertwined, it is first important to utilize various groundbased observations. These include those obtained from alarge atmospheric radar that measures coupling of theupper and lower atmosphere in the polar and equatorial
region - such coupling is key to driving variations in theupper atmosphere - and from ground-based multipoint
network observations deployed in the latitudinal direction

49
In the field of modeling, "explicitly" is often used with reference to directly writing down a specific process (e.g., temporal change of a variable) inmodel equations.

99

Theme 11: Interaction of the surface environment changes with solid earth
Abstract

ocean change?
Q4: How did the development process of the Arctic
Ocean and surrounding continents affect the surface
environment change on the time scales from tens of
millions of years to several billions of years?
Question 1 focuses on the hydrothermal system of the
Gakkel ridge, which is one of the currently active midocean ridges under multi-year sea ice and has not been
well researched. The aim of the research regarding Q1 is
to clarify the causes, the local ecosystem, and the effect ofoceanic circulation on the hydrothermal system of the
Gakkel ridge.
Question 2 applies to the observational study on thecurrent crustal deformation with the load change of ice
sheet, which is a unique phenomenon of polar regionswith a spatial scale of several thousand kilo-meters and atime scale of tens of thousands years. This study, in theareas of Greenland ice sheet, northern Canada and their
marginal ocean, aims to clarify the mechanisms of ice
sheet changes and viscosity structure of earth’s interior bygeomorphological, geological and geodetic investigations
together with modeling study.
Question 3 applies to establishing the formation historyof the Arctic Ocean on a scale with hundreds of millionsof years and the changes of atmosphere - ice sheet - oceaninteraction. Most of the Arctic Ocean floor remains
uninvestigated due to sea ice cover. The objectives of thisstudy are to (i) determine the history of the Arctic Ocean
seafloor via geophysical and geological investigations, (ii)clarify the changes in the atmosphere - ice sheet - oceaninteraction by investigating the reconstruction of thepaleoclimate and paleoenvironment by the sedimentcollection, and (iii) estimate the time for ice sheet
expansion in Arctic Ocean formation and the expansion
associated with the tectonic history of the Arctic Ocean.
The last question Q4 is on a change of the solid earthon the several billions of years scale, and aims principally

Large-scale surface activity of the earth occurs due tothe spreading and subduction of the ocean floor by thermal
convection of the Earth’s interior. This causes phenomena,such as the formation of new marine floor and thecollision of continents. The change in configuration of theocean and the continents at the earth’s surface due tothermal convection of the Earth’s interior is an importantfactor that causes a shift in the Earth’s surface
environmental changes, such as atmospheric and oceanic
circulation, and the development of ice sheets. On theother hand, changes in the volume and geographicallocation of the ice sheets and seawater on the surface ofthe earth due to climate change lead not only to changes
in sea level, but also to the deformation of the Earth, suchas crustal movement and mantle flow of the earth’s interior.
As just described, it has been thought that the climate andEarth interact with each other over a range of time andspace scales. However, the mechanisms are not clear yet
and to understand the whole Earth systemcomprehensively is an essential issue. In particular, theArctic region where interactions on various scales appear,such as the current crustal movement phenomenon due tochanges in load from ice sheets and the formation andfragmentation of the continents, which happens on a scaleof several billions of years, is key to understanding the
problem. With this theme, we have set the following fourquestions to be researched on the Earth changes withdifferent time and space scales in the Arctic region inorder to understand the interaction between the Earth andsurface environmental change under such conditions.
Q1: What is the interaction between the currently activehydrothermal system of Arctic mid-ocean ridges
and the marine environment?
Q2: How is the solid earth deformed by an ice sheetchange?
Q3: In the process of the Arctic Ocean formation, how
did the interaction of the atmosphere - ice sheet -Figure 42: Important research topics regarding interaction between solid earth and the surface
environment changes

100geological time scale from the early days of the earth
formation to now by a geological investigation in the
Canadian Arctic and west coast of Greenland, where
exists a stratum of approximately 3-4 billion years old, issuggested.

to analyze the earth’s surface environment change on thescale of 3-4 billion by the earth crust study with mainly
the geological investigations in the continent around theArctic region. The promotion of the research on thehistory of global environment change on the long

Introduction
which are plate boundaries, crustal movement
phenomenon due to the load changes of ice sheets overtens of thousands of years, which is a unique phenomenonin polar regions, and the formation and fragmentation of
the continent over several billions of years.
In this theme, we will describe the goals ofobservational research for the four questions aboutchanges to the Earth on different time and space scales,
which are necessary to understand the interaction between
the Earth and surface environment changes, and should be
developed intensively in the Arctic region in the future.
By promoting research based on these four questions andintegrating the results, we will clarify the relation betweenchanges to the Earth and the surface environment as asummation of various time and space scales, and aim toelucidate the interaction between the solid geospheresubsystem as well as atmospheric and oceanic subsystemin the Earth system.

In the Earth, changes on various time and space scales
are complex, such as movement caused by changes in theloads on the surface of the Earth along with changes of thesphere of fluid, including the atmosphere and the ocean,
as well as changes like formation and fragmentation of asupercontinent. Changes in the configuration of thecontinents and the ocean on the surface of the earth overhundreds of millions of years through to several billionsof years due to formation of the ocean and supercontinentbycontinental
fragmentation
broughtaroundtransformations to oceanic circulation and atmosphericcirculation, and greatly changed the surface environment.
On the other hand, like the change of the Earth with thechange in ice sheet load, the Earth’s responsive
phenomenon for the changes to the surface environment
exists as well. The Arctic region is a perfect field tounderstand the interaction between the Earth and surface
environment changes over various time and space scales,
including the current activity in the mid-ocean ridges,

Q1: What is the interaction between currently active hydrothermal systems of the Arctic
mid-ocean ridges and the marine environment?
ridges. In the Southwest Indian Ridge, which has a similar
axis of ultraslow-spreading ridge, high-density
hydrothermal activity, like that found in the Gakkel Ridge,
has not been found. Even in the slow-spreading Mid-

a. Importance and current status of research
The mid-ocean ridges and back-arc spreading system
are a series of active volcanoes, and many seafloorhydrothermal systems have been found along with themso far. A seafloor hydrothermal system is a place to emit
the earth’s internal energy and reducing gases, such ashydrogen sulfide, methane, and hydrogen. It is also
important for the concept of circulating the Earth’s heatand substances, such as forming hydrothermal deposit. It
is known that the chemical composition of the hot water
which erupts there varies depending on the kind of rocks
or heat source of the seafloor and each fountain supports
different type of ecosystems respectively.
The Gakkel Ridge is one of currently active mid-ocean
ridges located almost at the center of the Arctic Ocean andis a boundary between the North America Plate and theEurasian Plate. Since it exists under sea ice of the Arctic
Ocean, it is a difficult region to investigate (Figure 43).
The Gakkel Ridge is classified as ultraslow spreading(<12 mm/year) and it is a unique end member among the
mid-oceanic ridge systems in the world because of its
spreading speed, geographical location, and structure.
Several investigations by observation vessels, aircraft,and submarines have been conducted at the Gakkel Ridge
so far. As a result of such an investigation between the
United States and Germany conducted in 2001 as
AMORE 50 , it is estimated that many hydrothermal
activities are distributed with high density on the ridge
axis of the ultraslow-spreading Gakkel Ridge (Edmonds
et al., 2003 (Figure 44)). Generally, it is thought thatmagma activity is less active and the amount of thermal
release is small along the axis of ultraslow-spreading
50

Figure 43: Bathymetric chart of the Arctic Ocean,
information added to Jakobsson et al., (2008)

AMORE: Arctic Mid Ocean Ridge Expedition

101

Atlantic Ridge, such high-density hydrothermal
activity has not been confirmed. For the Southwest
Indian Ridge and Mid-Atlantic Ridge, it has beenthought that the fault is largely associated withhydrothermal activity but this does not explain
everything for the hydrothermal activity of the
Gakkel Ridge. It is suggested that such hydrothermal
activity may be related to the kinds of rocks aroundthe hydrothermal system as well (Michael et al.,2003). In addition, biologically, it is expected to finda new chemosynthetic community in the uniquehydrothermal system of the Gakkel Ridge where
high-density hydrothermal activity exists. In 2007,
the AGAVE 51 expedition investigated thehydrothermal system in the Gakkel Ridge under the
initiative of the United States by using a joint AUV
including Sweden, Germany, and Japan.
Unfortunately, they could not find hydrothermal
vents. However, with the investigation around theextremely deep ridge axis at approximately 4,000 m
at 85° E, the data collected suggested explosive
volcanic activity (Sohn et al., 2008) and yellow
fluffy mats of bacteria which grow in lowtemperature region (Shank et al., 2007). After that, ahydrothermal system with black smokers was foundin the Mohns Ridge, south of the Gakkel Ridge, forthe first time and it is confirmed that biota with thehydrothermal system is different from the one in the
Mid-Atlantic Ridge, south of the Mohns Ridge(Pedersen et al., 2010). From the AMORE
expedition, it is only estimated that there is highdensity distribution of hydrothermal activity in the
Gakkel Ridge so further detailed exploration on theaxisof the ridge is required in order to search for the
distribution of hydrothermal vents, the cause ofhydrothermal activity, and a biological community
existing off such activity, which are unique among theridges in the world but have yet to be confirmed. In
addition, an influence on oceanic circulation of heat flux
by hydrothermal activity of the Gakkel Ridge is estimatedto be low because it is a spot contribution even though thedensity of the hydrothermal activity is estimated to be high.
However, this also needs to be verified by actual
observation data.

Figure 44: Areas where hydrothermal activities are suggested
in the Gakkel Ridge (Edmonds, et al., 2003)

consider specifications and operational forms.
For identifying hydrothermal vents, we narrow therange of investigation by acoustic probing of seafloor
topography by observation vessels, understand thecomposition of hot water by detailed physical andchemical measurements, and estimate existence andlocation of areas of hot water. Then, we conduct anobservation and investigation of seafloor. For explorationof the cause of hydrothermal activity and a biologicalcommunity existing with such activity, after identifying
the hydrothermal vents, we observe the hydrothermal
vents and their periphery by ROV as well as the rocks andorganisms. Furthermore, in order to search for the causeof hydrothermal activity, it is necessary to clarify the
structure below the seafloor by conducting seismic
exploration
aroundthehydrothermal
vents,
electromagnetic
exploration,
andgeomagnetic
exploration. For estimating the temperature of the hotwater area and fluctuations in the material flux, it is also
necessary to carry out long-term fluctuation
measurements of the marine physical and chemicalcomposition in the hot water area.

b. Future research
For identifying hydrothermal vents of the Gakkel Ridge,
investigations using subsea robots, such as ROV or AUV,
are necessary. Since the Gakkel Ridge exists under sea ice,
icebreakers are required to deliver the subsea robots. For
explorations with subsea robots, it is essential to conduct
seafloor topography and ocean observation on a ship by
icebreakers in advance. In addition, since there are notmany actual exploration examples yet for explorations
under sea ice by subsea robots, it is also necessary to

Q2: How is the Earth deformed by changes in ice sheets?
The changes in ice sheets are associated with the mass of
the ice sheet and the mass change of seawater, for example
when ice sheets melt and flow into the sea, it brings achange of sea level. This generates changes in the surface
load which in turn produces a deformation of the Earth.
This phenomenon is called glacial isostatic adjustment

a. Importance and current status of researchThis question applies to deformation phenomena of the
Earth caused by changes in ice sheets over a time scale ofseveral years to several tens of thousands of years. The
load from the ice sheet is one of the surface forces (surface
loads) which works as pressure on the surface of the Earth.
51

AGAVE: Arctic Gakkel Vents Expedition102

Sweden, change in height and gravity in a long-distanceleveling route is measured (Figure 45) and estimation of
mantle viscosity is made as well (for example, Ekman and
Mäkinen, 1996).
When ground-based observation by space geodesy
technology, such as Global Navigation Satellite System(GNSS), became widely used in the late 1990’s,
continuous observation of crustal movement using thistechnology began in many spots of the polar region.
Currently, monitoring observation of crustal movement by
GNSS is being conducted in considerably high density inNorth America and Greenland (for example, Sella et al.,2007, Figure 46). In addition, in the beginning of the
2000s, observation of changes in ice sheet volume using
satellite gravity mission and satellite altimeters started
making it possible to estimate variation by PGR as well
(Barletta and Bordoni, 2009). Recent satellite geodetic
observation allows for high spatial and temporal
resolution, however, a phenomenon reflecting the viscose
structure of the mantle is characterized by its slow
fluctuation velocity and small amount of displacement so
approximately ten years’ worth of observation data mustbe accumulated in order to detect accurate crustal
movement velocity with GIA even with the current stateof-the-art observation technologies. Also, as describedabove, these observation data include crustal movementwith the past changes in ice sheets (viscous movement)
and crustal movement with the current changes in ice
sheets (elastic movement), and since the former is mainly
necessary for reconstruction of the history of ice sheet
melting and estimation of mantle viscosity rate, separatingthese is also a big issue.
The viscosity rate of mantle is an important parameterto determine movement of the earth’s interior related toplate tectonics, but there are only a few methods toestimate the viscoelastic structure of mantle based on
known phenomenon. If it becomes possible to estimate(GIA) and it differs according to the time and space scalesof the change of load. It is known that the Earth responds
elastically to load changes on a short time scale andresponds viscously to load changes over several thousand
years. Since the change in ice sheets covered in thisquestion is a phenomenon which is on a time scale ofseveral tens of thousands of years at the longest and on a
space scale of several thousand kilometers, it brings both
viscous and elastic deformation to the Earth on a global
scale.
The GIA research in the Arctic region is being advanced
mainly with three approaches of geomorphic andgeological investigations, geodetic observation, andnumerical modelling. These are for crustal uplift after theend of the last glacial period, or post glacial rebound(PGR) (for example, Peltier, 2004). PGR is a viscous
deformation phenomenon in which most of the continental
ice sheets covering North America and Northern Europe
in the last glacial maximum 52 melted and disappeared
approximately 6,000 years ago but the crust still continues
to rise slowly by buoyancy. In recent years, as an impact
of ongoing global warming, a rapid decrease in theGreenland ice sheets and glaciers of the Canadian Arctic
Archipelago have been reported and it is becoming clearthat the changes in these ice sheets create elastic
deformation of the Earth as well.
The most important issue for research on deformationof the earth with the changes in ice sheets is to clarify thehistory of expansion, shrinkage, and increase and decreaseof distribution of ice sheets after LGM (the history of ice
sheet melting). If we can determine this history of ice
sheet melting with high accuracy, we can accurately
calculate the impact that the deformation of the Earth withice sheet melting has on sea-level changes. This will be an
important contribution to improve a degree of accuracy
when predicting sea level rises with ongoing global
warming. If we can understand details of the size anddistribution of deformation of the Earth from past topresent, we can reconstruct the history of ice sheet melting
after LGM. Therefore, we hope that this shows theimportance of this question, which is an investigation of
the deformation of the Earth with the changes in ice sheets.
As physiographic and geological approach, byclarifying a relative altitude of sea level in the past throughdistribution of fossil shells and coral reef, the geologicalinvestigation on beach topography and glacial topography,
and investigation on seafloor sediments, the changes ofvolume of seawater (volume of ice sheet) over the past
several tens of thousands of years and the history of upliftand sedimentation of crust are estimated. Based on this,the change in the past distribution of ice sheets of polar
opposites can be reconstructed by comparison withcalculated values of GIA model taking into account elastic
deformation of the Earth (for example, Peltier, 2004).
However, with regard to the distribution of ice sheets byregion, there is a large difference between the suggested
models. For example, for a contribution of each ice sheet
for an ice sheet melting event with rapid climate change,
which occurred approximately 14,000 years ago, adecisive conclusion has yet to be made.
As for geodetic observation, crustal uplifts in the region,
where PGR is progressing, is observed as a decline inaverage tide level according to tide level observations
over the past 100 years (for example, Barnett, 1984). In
52

Figure 45: Postglacial uplift in Scandinavian region which
was observed from 1892 through 1991 (unit is mm) andgravity measurement line (after Ekman and Mäkinen,
1996)

Last Glacial Maximum (LGM) approximately 20,000 years ago

103and drilling of sediment in regions including Northern
Greenland and the Canadian Arctic Archipelago, whichhave been observed very little. Especially in the past, sealevel altimeter data of the coastal area of Greenland islacking in both quantity and quality, and this is a factor ofindeterminate reconstruction of the history of ice sheet
melting in Greenland. In order to enable observations like
this, it is essential to improve the convenience of field
investigation by making it possible to move to targeted
local coastal observation point using icebreaker-basedhelicopters and to introduce new geomorphic
investigation technologies, such as ground-based laser
scanner.
On the other hand, regarding the seafloor andcontinental shelves, it is necessary to conduct seafloor
topography and geological investigations using ROV53 or
AUV 54 as well as material sampling and to advancedevelopment of seafloor sediment core collection
technologies.
Next, regarding geodetic observation, ground-based
observation has already been conducted in considerable
high density and we should move towards observations at
the bottom of the sea for the next ten to twenty years. To
do so, we should develop and introduce a system forobserving submarine crustal movement, which combines
marine GPS operable in the Arctic region and equipment
for echo ranging and seafloor observation. Also, theestablishment of an observation network which can detectcrustal movement with an accuracy of 1 cm at the bottomof the sea should be promoted. In addition, in order tocalculate wide-area ice sheet changes and crustal
movement, it is clear that we should use satellite geodetic
data, such as satellite gravity mission, satellite altimeters,
and synthetic aperture radar, more than ever.
For improving accuracy of future forecasts of global
warming, it is essential to reduce the indeterminacy in themodel. To do so, it is necessary to develop a model whichtakes into account various complexity and processes aswell. For example, we can incorporate the influence ofhorizontal heterogeneity of viscosity of the earth’s interiorand combine this with ice sheet flow models into theviscosity rates or distribution of mantle more accurately
by comparative research of ground-based and satellite
observation at high spatial and temporal resolution as wellas numerical model calculations taking into accountvarious viscoelastic structures of mantle, it will be asignificant contribution to research fields in physics
dealing with the Earth’s interior.
As the Japanese contribution to the GIA research in the
Antarctic region, the Japanese Antarctic Research
Expedition conducts organized observation of crustal
movement, gravity measurement, and geomorphic andgeological investigations at Syowa Station and thesurrounding bare rock area. As a result, it became clearthat the crust currently up-thrusts at a rate of 2-3 mm per
year at Syowa Station and its surrounding area, and thisproduces corresponding changes to gravity.
Also, it clarified that the neighborhood of Syowa
Station has not been covered by ice sheets since 45,000
years ago, including LGM, and it necessarily did notsynchronize with expansion of ice sheets in the Northern
Hemisphere. However, in the Arctic region, observationof crustal movement and gravity measurements are
conducted in Alaska and Ny-Ålesund in Norway.
Annually 5-7 mm of uplift is observed in Ny-Ålesund.
b. Future research
In order to advance the understanding of this question
further, there is an urgent need to develop observational
research in areas with little observation data. For example,
so far the investigation area is limited mainly to land andthe seafloor largely remains unobserved. Not surprisingly,
changes are occurring on the seafloor, such as tocontinental shelves, and it is expected that detailed terrain
observation of continental shelves will contribute tocontrol the area where ice sheets are expanding. In
addition, observation of crustal movement at the bottomof the sea, away from ice sheet loads, is important tocontrol the ice sheet model and viscosity structure as well.
First, with geomorphic and geological investigations, itis necessary to conduct traditional investigation, such as
the current geomorphic investigation, material sampling,

Figure 46: Crustal movement observed by GPS (Left) vertical component (Right)
horizontal component (after Sella et al. 2007)

53
54

ROV: Remotely Operated Vehicle
AUV: Autonomous Underwater Vehicle

104organizational research and observation activities.
Furthermore, model development research is in a similar
situation and we should advance cooperation with otherfields, such as the field of paleoclimate modelling, and weshould urgently establish a further framework, including
development of researchers who will be engaged withsuch observations.

current model. Also, to establish these models, it will benecessary to develop computational skills and highresolution data analysis methods.
With regard to observation and research structures,
observation in the Arctic region in this field is still
conducted by individuals and observation by a small
number of researchers so we need to work on

Q3: In the process of forming the Arctic Ocean, how did interactions between theatmosphere, ice sheets, and the ocean change?
including the Eurasian Basin.
a. Importance and current status of research
The ACEX (Arctic Corning Expedition-IODP Leg 302)
The configuration of the continents and the ocean on(Backmanet et al., 2006), which was conducted in 2004 in
the surface of the earth changes by thermal convection in
the Lomonosov Ridge, was able to obtain a record thatthe earth’s interior, such as expansion and subduction ofdates back to 55 million years ago and it became clear thatthe ocean floor as well as formation of concomitants andcooling of high latitude of the Northern Hemispherefragmentation of the continents, and it largely affects theunusually began with the Antarctic region in the middle
earth’s surface environment, including oceanic circulation
Eocene epoch (Moran et al., 2006). This suggests that a
and atmospheric circulation. Especially the formation of
decrease in atmospheric CO2 concentration for seafloor
the ocean floor becomes a factor to largely change oceanic
circulation, so research combining a history of
sediments through fixed organic matter by establishment
development Arctic Ocean floor, which is a starting pointof the Arctic Ocean is a major cause of global cooling inof the current deep circulation, and reconstruction of thethe Cenozoic Era rather than regional climate change by
paleoclimate and paleoenvironment will clarify thetectonic events, such as establishment of the Drakehistory of change in oceanic circulation change in the
Passage.
process of formation of the Arctic Ocean and a history ofHowever, in order to understand the relationshipcontinental ice sheet development, and it will largely
between the development process of the Arctic Ocean andcontribute to elucidate temporal change in the interaction
the surface environmental changes, especially the
between the atmosphere, ice sheets, and the ocean. Since
relationship to absorption of greenhouse gases, fixation as
the seafloor of the Arctic Ocean is covered with sea ice, it
organic matter or hydrates, transition of oceanic
is difficult to conduct investigations so there are still many
circulation, and history of the development of continental
matters to solve regarding geological structure, etc. under
ice sheets, it is necessary to reconstruct and analyze thethe seafloor. The Eurasian Basin was created in the
paleoenvironment in detail by using sediments together
Cenozoic Era by activity of the Gakkel Ridge in the Arctic
with tectonic research of the Arctic Ocean.
Ocean, which still continues today.
The Arctic Ocean is a basin divided into two largeb. Future researchbasins; the Eurasian Basin and the Amerasian Basin, by
The Alpha Ridge and the Mendeleev Ridge will be a
the Lomonosov Ridge, and its history of development is
key to understand the history of the Arctic Ocean
relatively well understood from geomagnetic anomaly
development, especially the tectonics of the Amerasian
lineation, which is used for identifying the age of theBasin. To clarify the causes of these, it is important toseafloor. On the other hand, it is consideredthat the Amerasian Basin was created after the
Mesozoic Era, however, its geomagnetic
anomaly lineation is only identified in part of
the Canada Basin (Vogt et al., 1982) and mostof its development history remains unclear.
Especially for the causes of the Alpha Ridgeand the Mendeleev Ridge in the Amerasian
Basin, there are still various theories,
including; 1) by continental origin 2) by the
expanded axis of the seafloor in the past, 3) byplume origin, or 4) by subduction, making thisa controversial issue. So far little research,such as seismic experiment, has been carriedout and it is suggested that the Alpha Ridge isocean crust (Jokat, 2003). On the other hand,
the research shows that continental crust may
be included in the Mendeleev Ridge(Lebedeva- Ivanova et al., 2006). Research
estimating the structure under the Amerasian
Basin using gravitational data is being
conducted as well (Alvey et al., 2008).
However, there are still not enoughFigure 47: Color image of geomagnetic anomaly data of the Arctic
investigations and we hope to elucidate the
Ocean (Verhoef et al., 1996 and Glebovsky et al., 1998)
history of development of the Arctic Ocean,105

Figure 48: Seismic velocity structure near the Mendeleev Ridge (Lebedeva-Ivanova, et al., 2006)

ocean with the formation process of the Arctic Ocean by
combining tectonic information of the whole Arctic Ocean
and analysis of the paleoenvironment and paleoclimate,such as transition of oceanic circulation and the history ofcontinental ice sheet development.
Observations described above will lead to futureinternational deep sea drilling projects in the Arctic Oceanarea, such as IODP. For deep sea drilling in the Arctic
Ocean area, Japanese researchers participated in, andmade significant contributions to ACEX, which was
conducted in the Lomonosov Ridge in 2004. However, theJapanese research community has not participated in the
deep sea drilling project in the Arctic Ocean area by IODP,
which is currently being discussed. We hope Japan will
participate in, and contribute to, such international drilling
projects in the Arctic Ocean area and it is necessary todevelop the Japanese research community by activating
research and observation activities regarding the Earthscience in the Arctic Ocean area.

conduct an Earth geophysical exploration, including
seismic experiments, and geological explorations, such as
rock collecting, at the widest area possible for these ridges
and their surrounding ocean area. For verification ofreconstruction and consistency of geological structure
before the ocean floor was formed, understanding thegeological structure of the continent around this oceanarea will be necessary as well. Based on these, we aim toclarify the development history and the origin of the Alpha
Ridge and the Mendeleev Ridge as well as theirsurrounding ocean area, and to elucidate the tectonics of
the whole Arctic Ocean.
Also, in order to clarify the surface environmental
changes along with these developing processes, we willconduct reconstruction of paleoenvironment andpaleoclimate from sediment samples. In addition, tounderstand transition of oceanic circulation after the
Cenozoic Era and history of ice sheet development, we
will conduct sediment collection in the Eurasian Basin as
well. Ultimately, we will clarify the transition of theinteraction between the atmosphere, ice sheets, and the

Q4: On time scales of tens of millions, to billions of years, how did the development
process of the Arctic Ocean and the surrounding continents affect changes in the surface
environment?
a. Importance and current status of research
To understand changes to the Earth’s environment ontime scales of tens of millions to billions of years, which
is a relatively long geological time, is a major research
theme in the geosciences. The formation and developmentof the Arctic Ocean goes back approximately one to two
hundred million years ago and, so far, information on sucha time scale was obtained from exploration of the Arctic
Ocean floor (Figure 49).
In addition, complex geological information on crustdevelopment is recorded that dates back to thePrecambrian (> five hundred million years ago) in thecontinental region around the Arctic Ocean. By analysis,
combining continent’s geological information andgeophysical exploration of crust in the oceanic area,
research on the formation process of the Arctic Ocean andthe configuration of the continents and the ocean in the
Arctic area (paleogeography) has advanced until now(Figure 50).
As described above, only with analysis by combining
both continental and oceanic information, reconstructionof the past oceanic and continental developing processes
in the Arctic region can become possible. Also, we canobtain information which will be a basis to examine the106Figure 49: Geophysical and geological information of the seafloor in the Arctic region (Seton et al., 2012)

comparison with the past geological conditions of thecontinent and process of formation and development,
various models have been suggested (Figure 51).
As described above, research up until now has clearlyshown that stratum of various eras are distributed in the
Arctic region. Especially the existence of the oldest rockon the earth (the Acasta Gneiss), which is approximately
4 billion years old, in the Canadian Arctic andapproximately 3.8 billion-years-old rock, which is foundin the Isua region in the west coast of Greenland, provesthat the Arctic region is an appropriate field for researchon environmental change of the earth on an extremely
long geological time scales from the formation of the
Earth until today.
Also, in continental regions distributed in the Arctic
region, there are rocks which have undergone high-grade
metamorphism equivalent to exposure to the deep crust,and low-grade metamorphism which originate in shallow
regions of the crust where the extent of metamorphism isconsiderably less. Especially the latter can be an
appropriate research object for reconstruction of theenvironmental changes on time scales of tens of millions
to billions of years.
Furthermore, one important point of the Arctic regionis the existence of a 3.8-to-4-billion-years-old stratum
dating from the time the earth was created, which can beseen in the Canadian Arctic and the west coast ofGreenland (for example, Bowring et al., 1989; Nutman etal., 2007). Geographical restrictions like the “Arctic
region” does not carry any special significance on such atime scale. The research theme we discuss in this Q4 does
not aim specifically for Arctic environmental research likethat described in Q1 through Q3 above, it rather aims forenvironmental change research on a time scale of thehistory of the Earth by using geological information,
which is distributed throughout the Arctic region.
Due to the importance of that stratum distributed
throughout the Arctic region, a lot of geological researchhas been conducted so far. However, compared with otherareas that are more easily accessible, geological dataobtained from the Arctic region cannot be said to bequalitatively or quantitatively sufficient. Regarding the

Figure 50: Transition of past configuration of continents in the Arctic region (750-250Ma) (Vernikovsky et al., 2013)107

Figure 51: Reconstruction figure of past configuration of continents in the North Atlantic
Ocean area (Lorenz et al., 2012)

methods for dating and analysis with a combination of
isotope analysis focused on isotope (geochemical tracer),which will be an indicator of previous environmental
changes. The two secondary ion mass spectrometers
installed at the National Institute of Polar Research, will
be extremely important for such material scientificunderstanding.
Furthermore, based on research on component
materials of the crust, it is possible to conduct analysis ofcontinental crust heat flow under ice sheets, which isdifficult to measure directly (for example, Carson et al.,2014). For information of crust under ice sheets, analyzing
data from geophysical explorations (gravity andgeomagnetism) is essential. By combining such physicalinformation and information from rocks exposed on themargin of ice sheets, we can attempt to estimate geologicalconditions under the ice sheets. Also, by precisely
estimating geochemical information of rocks andradioelement content, which will be a heat source, we
think we can estimate heat flow in the crust under ice
sheets. As described above, it becomes possible to clarify
characteristics of the solid geosphere in the Arctic region
on time scales of tens of millions to billions of years
through closely linking estimation data of crustal structurewith analysis of data from geophysical exploration.
Geological investigations to obtain basic data forresearch does not require special devices or preparationand it is possible to conduct field investigation promptly.
Due to the remoteness of the Arctic Circle, as well as the
Antarctic, data from field investigations is severely
lacking. For geological investigations in Greenland andgeological research in Scotland and the Canadian Arctic
geological conditions there are considered to be an
extension of Greenland’s, the Japanese research

Earth’s surface environment on a time scale such as theage of the Earth. This means that analysis of changes tothe Earth’s surface environment on a time scales of 3 to 4
billion years will become possible through crustal
research in the Arctic region. In addition, by comparative
research with exposed deep crust (high-grade
metamorphic rock) from the same period, it is possible topromote research from the perspective of the interaction
between the Earth’s surface environmental changes andphenomenon occurring deep in the continental crust.
b. Future research
For a method to understand the question mentioned
here, it is necessary to comprehensively combine datafrom ground-based geological investigation andgeophysical exploration in the oceanic area. Specifically,
we will clarify the development history of the ocean floor
that dates back 100 to 200 million years ago through ocean
floor geophysical exploration. Due to a recent decrease of
sea ice in summer in the Arctic region, more regions havebecome accessible to research vessels, and it is also
possible to obtain new information by undersea
geophysical exploration using unmanned exploration
ships. Also, field geological investigations in continental
area will allow for the analysis of material circulation on
geological time scales for deep crust and surface crustfrom petrological, geochemical, and chronologicalresearch on matter constituting crust in the Arctic region.
In addition, we can conduct more accurate reconstructionsof past configurations of the continents by comparing
geological conditions of the continental areas to thedevelopment history of the ocean floor obtained from theoceanic areas. In order to clarify processes on suchgeological time scales, we need highly accurate analytical108

community has contributed more than a little so far. In the
future, we also need to efficiently organize field
investigative teams within five to ten years and should
actively work on research, including on-site geologicalinvestigations in the Arctic region. Through conducting
efficient on-site geological investigations in the Arctic
region based on accumulated know-how frominvestigations of the Antarctic, we will obtain thenecessary base geology data to begin answering thequestion.

109

Theme 12 Basic understanding on formation and transition process of permafrost
Abstract

the change of ground temperature, the amount and thestate of ice and organic carbon storage. Permafrost study
should focus on modeling and quantifying the process ofchanging permafrost based on distributional information.
We need to integrate our scientific knowledge andtechniques with the modeling in order to understand the
behavior of the permafrost land system and the variationof arctic environment system.
In this theme, the following four questions will be
discussed.
Q1: Permafrost distribution: how is the permafrost in
the arctic distributed, both horizontally (in terms ofspace) and vertically (in terms of depth)?
Q2: Permafrost composition: what material does thepermafrost consist of, and how heterogeneous is it?
Q3: Warming and thawing of the permafrost: what isthe process, and on what scale does it happen?
Q4: Permafrost-Atmosphere-Snow-Vegetation system:
what is its structure and behavior?

Permafrost regions occupy approximately 25% of theland area. It is one of the major factors affecting the Arctic
environment through the complicated feedback of heatand materials with atmosphere and vegetation, etc. It is apotential GHG source due to the surface thawing.
However, there is a lack of detailed scientificunderstanding on the present state and dynamics ofchanging permafrost distribution. Therefore, there isconsiderable uncertainty regarding the future projection of
permafrost variation. The main reason for this situation isthat the spatial heterogeneity of the permafrost is large, theobservational sites are limited in terms of representing thewhole region, and observation from satellites ischallenging. It is therefore necessary to develop new
observation techniques and to improve the existing
methodology, as well as to expand the observation sites
and to carry out multi-point measurements. It is becoming
increasingly important to improve the knowledge ofdetailed permafrost distribution and the heterogeneity of
its composition, and to increase the information regarding

Introduction
quantitatively predict the effects of melting permafrost on
water circulation, vegetation, climate, and human society
over a wide area, there is an insufficient amount of
currently available basic information relating topermafrost (e.g., physical properties, amount of stored
carbon, spatial distribution of underground ice, etc.) and alack of understanding of feedback processes (e.g., changes
in vegetation due to the fluctuation of permafrost, impacts
on climate due to such changes, etc.). Since permafrost
fundamentally does not exist on the ground’s surface,remote and non-contact observation methods (remotesensing) have not yet been established for use, and direct
observations require efforts such as excavation. Therefore,
limited observational and monitoring examples exist for
use in gaining an understanding of the current condition
and fluctuation of permafrost over a wide area. Comparedto other snow and ice elements (sea ice, snow cover, andglaciers), there is a significant delay in gaining an
understanding of the spatial distribution and fluctuating
patterns of permafrost, and predictions of responses toglobal warming have a wide range of uncertainties.
This report shows that permafrost is closely related tochanges in ecosystems (Theme 3), effects on water
circulation due to changes in snow and ice elements(Theme 4), and that it is important as an information
source for use in paleoenvironment reconstruction(Theme 6). Discussions herein also mention the effects ofmelting permafrost on regional communities in the Arctic
region (Theme 7). Using a number of various research
topics, this study aims to gain an understanding of how theeffect of permafrost changes needs to be quantitatively
reflected in predictions of future global environmental
changes. In this respect, data accumulation is being
initiated internationally, and some projects are now
connecting observational data with models. In relation tothis Theme, we present areas in which there is aninsufficient understanding of permafrost over a wide area
(Arctic regions), and we then propose certain research
topics that need to be tackled in order to clarify future

Permafrost (please refer to explanations in “Box 8” forterms underlined throughout this document) exists
throughout most of the circumpolar region (Figure 52a),and is believed to occupy approximately 24% of the total
land area in the Northern Hemisphere (Brown, 1997). Not
only does it represent the largest snow and ice
phenomenon on Earth in terms of area, but it also enables
a complex exchange of both heat and substances between
the atmosphere and vegetation. It is therefore of
considerable importance in relation to fluctuations within
the Arctic environment. In this respect, there are concerns
relating to its impact on the future global climate from therelease of greenhouse gases accompanying the melting ofunderground ice, and the release of methane hydrate due
to destabilization of seabed permafrost. There is a strong
possibility of the irreversibility of potential changes inpermafrost in relation to global warming. For example,
thermokarst causes a chain of changes in the circulation of
local water, materials, and ecosystems due to the meltingof permafrost. In Eastern Siberia, permafrost with a highice content melted under a coniferous forest, causing
wetlands and lakes to form in depressions where the land
had subsided. Although these changes take several tens tohundreds of years to occur, organic carbon that has been
fixed over tens of thousands of years becomes fluidized
through these processes. Impacts on ecosystems andhydrological processes are major issues for regional
communities; however, damage to social infrastructuresuch as buildings, pipelines, roads, and train tracks due tothe subsidence of land is already becoming apparent. On
the coast and islands of the Arctic Ocean, shore erosion
due to waves has intensified with the melting of frozen
ground, and some regional communities have been forced
to relocate.
Until now, many studies have been conducted on thevarious phenomena and issues arising from the presenceof permafrost, using a number of typical and characteristic
locations as targets to gather information (e.g., Harris etal., 2009; Matsuoka and Ikeda, 2012). However, to110changes and impacts on the climate and environment.

Figure 52:(a) Permafrost distribution map based on groundtemperatures (from USGS Professional Paper
1386-A). Prepared by Dmitri Sergeev (UAF) basedon the IPA Circum-Arctic Map (Brown et al., 1997).
http://pubs.usgs.gov/pp/p1386a/gallery5fig03.html(b) Distribution of ice content. Revised IPA
Circum-Arctic Map. Ishikawa and Saito, Journal of
the Japanese Society of Snow and Ice (2006).
(c) Distribution of amount of organic carbon inpermafrost. Tarnocai et al. (2009).

111

temperature is short at shallow depths, and becomes
longer with depth.
Thick permafrost in Siberia, reaching down to several
hundreds of meters underground, contains a record ofclimate change on a scale of several tens of thousands ofyears. This is because temperature changes at the ground’s
surface influence the temperature of the soil at depths of
hundreds of meters underground, over periods of several
thousands and tens of thousands of years. However, since
the current climatic environment is reflected in thepermafrost temperature at shallow depths, the planar
distribution boundary of the surface layer of permafrost is
mostly determined by the current climatic conditions.

b. Characteristic properties of permafrost
The characteristic properties of permafrost are often
due to the dynamic behavior of water contained within it.
For example, since permeability of wet ground decreases
significantly due to freezing, the permafrost layer
functions as an aquiclude, and determines the growthenvironment of the vegetation above. In addition, due tothe effects of latent heat being released/absorbed duringfreezing/melting of soil pore water, the soil temperaturechange of permafrost tends to be suppressed, particularly
at around 0°C. As mentioned earlier, the damage toinfrastructure due to ground subsidence and risingaccompanying thermokarst and frost heave, depends onthe growth and disappearance of underground ice. To
understand fluctuations of permafrost and various
phenomena arising from such fluctuations, it is important
to conduct any evaluations with respect to the dynamic
behavior (amount and phase) of groundwater. Zhang et al.
(1999) estimated that the total amount of underground ice,down to 20 m underground, over the entire Northern
Hemisphere measures between 3 and 10 cm, withadjustments made for sea-level fluctuations. However,heterogeneity in the distribution is significant, and thereliability of the estimated values is low (Figure 52(b)).
The dynamic behavior of the organic carbon content inpermafrost is also of interest in relation to climate change.
From a global-scale soil database, the total amount oforganic carbon stored in permafrost has been estimated by
Zimov et al. (2006) as measuring approximately 1,000 Gt,
and by Tarnocai et al. (2009) as 1,700 Gt (Figure 52(c)).
These values are equivalent to approximately half of theorganic carbon on land, and twice the amount of carbon in
the atmosphere. If all the permafrost containing organiccarbon melts, the carbon will be released into theatmosphere as greenhouse gases in the form of carbon
dioxide or methane (permafrost carbon feedback),
potentially further accelerating global warming (Schuur etal., 2011). However, these processes require several
thousands to tens of thousands of years to occur, and suchpredictions are calculated based on limited field survey
results with many assumptions; thus, significant
estimation errors exist.

d. Key Questions in this Theme
To improve our basic understanding of the formationand transition processes of permafrost, it is necessary to
examine the following four topics, and any gaps in our
knowledge will be filled within the next five to ten years:
Q1:What is the distribution and depth of Arctic
permafrost?
Q2: What substances constitute permafrost, and what is
the level of heterogeneity?
Q3: In what manner and on what scale does permafrost
warm up and melt?
Q4:What are the structural and behavioral
characteristics of the permafrost–atmosphere–snowcover–vegetation subsystem?
The above topics are closely related to one another; forexample, the issues in Q1 and Q2 are related to an
estimation of the temperature of permafrost and the active
layer above (Q1), and the horizontal and verticaldifferences in the constituent (Q2), at a higher resolution
than presented in previous estimates. Therefore, thisrelates to an improvement in the accuracy of estimates forareas that cannot be directly observed.
The answers to Q1 and Q2 determine criteria such as anevaluation of the spatial scale of changes and the speed ofchanges, which are then considered in Q3. While focusing
on changes in the conditions that can occur over a
relatively short time frame, such as changes in the active
layer (Q3(1)) and the thermokarst (Q3(2)), it offers
information on the history of changes and the predictionof future changes on a time scale of one hundred years or
more. It also touches on ground temperature changes in a
deep part of permafrost that is climatologically important(Q3 (3)). Q4 focuses on the interaction between
permafrost and vegetation, snow cover, and atmosphere.
In addition, the importance of gaining an understanding of
the climate and ecosystem of this frozen ground isemphasized, in addition to clarifying behavior.

c. Distribution of permafrost and the time scale offluctuations
Fluctuations in the ground temperature of permafrost
can be considered to be approximately controlled by heat
conduction from the ground’s surface. This can be mostly
explained as the result of propagated fluctuations of theground surface’s temperature through attenuation anddelay (Lachenbruch and Marshall, 1986). Thus, theresponse time of changes in the permafrost ground

Q1: Permafrost distribution: how is the permafrost in the arctic distributed, bothhorizontally (in terms of space) and vertically (in terms of depth)?
being accumulated. However, since permafrost is definedby its temperature, an accurate distribution cannot be
observed in the current condition due to the following: 1)
boreholes are required to enable direct observations ofgroundtemperature
measurements,
andsuchmeasurements are limited in terms of the spatial
representation of individual data; 2) as permafrost is
distributed over differing depths, there are only a small
number of boreholes that are sufficiently deep to accessa. The importance of research and its current state
Gaining an understanding of the distribution of
permafrost gives us fundamental information, and basedon previous research the International Permafrost
Association (IPA) is compiling a permafrost distributionmap (Figure 52(a)). In addition, at the international
observation network known as GTN-P, which is promotedby the IPA, the results of soil temperature change
observations and changes in active layer thicknesses are112Box 8 Fundamental understanding of the formation and transition processesof permafrost
Permafrost is defined as ground(sediments and bedrock containing ice
and organic matter) that remains at atemperature of 0 °C or lower for aperiod of at least two years. However,permafrost may melt with climatechange and anthropogenic activities,
and therefore is not “permanently”
frozen ground, as the name suggests.
To express the temperature change,
growth,anddisappearanceofpermafrost, the use of a term such as“multi-year frozen soil” has been
proposed. The permafrost zone is anarea that contains permafrost, and isfound in areas of high latitudes and athigh elevations; the latter has acomplex distribution depending on theterrain. Figure 53 shows a schematic
diagram of the 3D distribution of
permafrost and its classification basedon horizontal distribution in areas ofhigh latitudes. The percentage ofpermafrost for an area of groundsurface is determined in relation tocontinuous,
discontinuous,andsporadic permafrost.
Active layer: This is the surface layerof permafrost that undergoes arepeated cycle of melting (summer)and freezing (winter), and is an
important place for the movement ofsoil moisture, plant activity, andmicrobial activity.
Thermokarst: A process that forms
uneven terrain through the melting of
ice-rich permafrost. In addition to land
subsidence from melting, it leads toerosion along ice ridges and large-scaleslope failure along coasts and areas ofincline. Lakes that form in depressions

Figure 53: Schematic diagram of three-dimensional
distribution of permafrost and the classification of continuous,
discontinuous, and sporadic permafrost (Encyclopedia ofSnow, Ice and Glaciers).

due to thermokarst are called thermokarst lakes(melting lakes). Depressions known as Alas, which arecommonly found around Yakutsk in Siberia, are also atype of terrain related to thermokarst.
Talik: An unfrozen part of permafrost; although it issurrounded by permafrost, talik remains unfrozen
throughout the year.
Yedoma layer: A permafrost layer with a high icevolume of 65–90% and a large storage of organiccarbon. The name is derived from the native languageof northeastern Siberia, and is occasionally referred toas complex ice. It is found in the northeastern andcentral parts of eastern Siberia, north-central Alaska,
and northwestern Canada, and measures several
meters to several tens of meters thick.

Figure 54: (a) Distribution of the Yedoma layer in Siberia. (b) An outcrop of the yedoma layer in the processof being eroded at the Duvannyi Yar site on the Kolyma river (the body of ice is outlined by the dotted line);from Vonk et al. (2013).

113

breakthrough is required in this respect. Granted,
exploring possibility is always necessary.

such depths, and therefore the accuracy of vertical
distribution estimates remains low; and 3) definite
identification cannot be made using remote observations
such as those of satellites. Due to these limitations, ourcurrent knowledge of the distribution of permafrost relies
on estimations made from a limited number of observation
points, both geographically and in terms of vertical
distribution.
In addition, the distribution of permafrost is
characterized by significant heterogeneity. For example,
Figure 53 (Box 8) presents a schematic diagram of
permafrost distribution, where it can be seen that taliks
form downstream of lakes and large rivers, and that theboundary areas of distributions reflect various conditions,
resulting in a spatially complex structure. However,classifications of continuous, discontinuous, and sporadic
permafrost, that are used in the current distribution map,
have succeeded to a certain degree in representing theenvironment of frozen ground as it changes from acontinuous distribution to a mottled and island-like
distribution. Although the division boundaries are marked
with lines in the Figure, the position of these lines changes
depending on the areas chosen to calculate the distribution
ratio of permafrost. In addition, although the continuity ofthe permafrost distribution decreases, the thickness of theactive layer may be extremely thick depending on thelocation, and contain fossil permafrost at depths (formed
during the past cold periods–which may be in the process
of melting), and thus the spatial patterns of permafrost
boundaries become complex, as shown in the Figure.
Similarly, the ground surface conditions of permafrost in
steep mountain regions vary greatly depending on theslope direction and snow cover distribution, and thus
heterogeneity of the distribution increases in relation tothese conditions. These large variations are currently notincluded in the distribution map of wide areas.
Under such conditions, it is difficult to identify any
changes in the distribution in response to climate change.
Furthermore, as observation points are limited, it isdifficult to separately identify changes in permafrost
distribution that progress in response to factors associatedwith climate change other than temperature. As a starting
point in various discussions relating to changes in frozen
ground over a wide area, it is important to advance beyond
the rough understanding presented in the distribution map
and to determine the heterogeneity, as such knowledge
will give us an understanding of the distribution of frozen
ground.

(2) Improving and combining existing technologies
To enable identification of changes in distribution, theimprovement of existing observation methods is also
necessary. In addition to the continual expansion of direct
observations of ground temperature through boreholes
collected by GTN-P, developments in the following
directions are also required:(3) Utilizing satellite data, and data analyses incombination with climate models
To handle planar information, utilization of satellite
data is necessary. For example, information of groundsurface classification, brightness temperature of theground’s surface, and snow cover are gathered fromsatellites, and the condition of frozen ground can be
estimated using a combination of such information. By
inputting this information into a land surface model, it
would thus be possible to obtain the ground temperature
distribution as a model output.
(4) Development of an estimation method thatcombines multiple observation methods
In addition to the above-mentioned satellite data,
multiple index data (such as physical survey data andground surface temperature observations) can be
combined, and a comprehensive method that estimates
permafrost distribution can be developed.
(5) Improvements in presenting the permafrost
distribution
In addition to previous monovalent expressions of
distribution, information related to the distribution on ascale which is the same as, or below, the estimated gridsize can be treated as a probability distribution function.
Furthermore, a distribution boundary with a sufficiently
large width could be defined to improve the expression of
distribution. When matching the permafrost distribution
with the model output, or when matching it with thephysical values obtained from satellite observations, thenecessary data expression format could then be prepared
to enable various expressions.
(6) Evaluation of heterogeneity
There are various levels of heterogeneity in groundsurface conditions such as ground temperature, thicknessof the active layer, thermophysical properties, and snow
cover. If only one measurement point is used, it is notpossible to evaluate heterogeneity. Although the CALM
site sets a 100 m x 100 m grid to determine the thicknessof the active layer in which to conduct multi-point
observations, most other observation areas have only avery small number of observation points. If a simple
observation method is employed, multi-point observations
can be carried out in which the spatial spread is taken into
consideration for each site, and the heterogeneity(variability in values) can then be evaluated.

b. Future studies
To gain a better understanding of permafrost
distribution, it is considered that studies should be
conducted in the following areas:(1) Development of observation and identification
methods
We intend to develop new observation methods basedon novel principles, and develop and improve analgorithm that can extract information highly correlatedwith the distribution of permafrost determined using
satellite data. There is currently a difficulty in determining
the bedrock structure from satellite data, and therefore a114

Q2: Permafrost composition: what material does the permafrost consist of, and how
heterogeneous is it?
limited and vague at this point. Previous studies haveestimated the amount of ice and organic carbon by making
full use of limited information, but it is necessary toremember that this information is currently insufficient.
Therefore, it is necessary to quantitatively discuss thelevels of errors inherent in each method.
In future studies, it is considered essential to steadily
improve the estimation accuracies by expanding
observations and by gradually integrating alreadyavailable information. Ingenious ideas are required toenable efficient observations, such as selecting
observation points using ground surface classifications
obtained from satellite data. There is also room for further
improvement in presenting distribution information.
Generally, as discussed in Q1, the temperature ofpermafrost and the content ratio of its constituents have ahigh spatial heterogeneity, and are dependent on the scale;thus, a method of presentation is required that would
retain the obtained observational information. The content
of underground ice at a given point reflects the current
conditions such as weathering of base materials, climate,terrain, and vegetation as well as its history. If the
predominant factor for each area could be determinedusing such information, the size of the uncertainty could
be reduced.
One possible direction for future study would be thegeneration of data that includes a sub-grid (on a grid sizeor less) of geographical information. With typical data
presentation, the status values in each grid (terrain,
vegetation, snow cover, temperature, thermal properties ofsoil, and grain size characteristics) have been implicitly
assumed as uniform, even though it is difficult to handle
data from areas where heterogeneity in the grid becomessignificant, such as in mountain ranges and areas of
discontinuous permafrost. However, it is not realistic to
use a differential approach that makes the grid evensmaller to deal with this issue. Thus, a framework could
be designed to present the constituent ratio of permafrost
as a statistical representation that includes heterogeneity(probability distribution, variance, maximum, minimum,etc.), by retaining the current grid size and combining thevalue of each status inside the grid. This idea has not been
sufficiently implemented internationally yet; thus, there isa high possibility that Japan will lead its development, as
discussed below.
The mid-latitude alpine regions and discontinuous
permafrost zones (near Fairbanks, Alaska; western
Siberia; alpine regions of Mongolia and Japan) are areas
currently studied, and are suitable for testing the abovementioned various approaches to present permafrost
compositions. In these areas, distribution and compositionof permafrost are not uniquely determined by climate, butthey are strongly controlled by local terrain, hydrology,
and ecological conditions and have large variations (e.g.,
Ishikawa et al., 2012). Therefore, explanatory variables(status values) and objective variables (permafrost
composition) can be easily compared and examined.
It is also considered that observational design isnecessary, with a refinement and generalization of models
that allows a systematic and seamless increase in scalea. The importance of research and its current state
Permafrost is defined by its soil temperature, but it isalso a mixture of substances in various proportions, suchas base materials (soil particles and bedrock), water (iceand unfreezable water), and organic carbon. The content
ratios of these substances determine the soil mechanicalcharacteristics and thermal properties, and control
changes in permafrost conditions (which are discussed in
Q3 along with external factors such as temperature andprecipitation). The melting of permafrost fluidizes thesesubstances, and sends a feedback to the climate via theland and atmospheric composition in the form of atransformation of the terrain, wetting of the soil and therelease of greenhouse gases. Gaining an understanding of
the substance group that constitutes permafrost, inparticular the content ratio of carbon and ice, is essential
for understanding the effect of the dynamic behavior ofcarbon and water circulation processes on the Arctic land
surface, and the future of these processes. It also
contributes to predictions of global climate change.
Although these issues have been considered byscientists from various fields for a long time, there is alack of understanding over a wide area, and estimates oforganic matter and underground ice discussed earlier(Figure 52(b), (c)) contain significant uncertainties(Zhang et al., 1999；Zimov et al., 2006； Tarnocai et al.,2009) because there is a definitive lack of quantitative data.
In addition, it should be noted that such estimates are total
values, which although useful when evaluating thepotential effects of the total loss of permafrost, they do notconsider the actual fluctuations of permafrost and how thisvaries greatly over both time and space. To understand thecirculation processes of these interacting dynamic
behaviors (Q 3), the content ratio of the substance groupthat constitutes frozen ground, and its heterogeneous
spatial distribution must be considered in the analysis.
Among studies using numerical models, few have used
the underground distribution of permafrost ice and thecarbon cycle, and models that do exist are simplified.
Earth system models that include the carbon cycle model
already exist; however, to simulate the environment of
permafrost for the above-mentioned purposes,
calculations need to begin in the last interglacial period,and changes should be tracked. It is extremely difficult to
conduct such a long-term experiment in combination withadvanced climate models, given the ability of current
computers and the reproduction capability of models, andalso because of the lack of data available to determine
boundary conditions. Currently, heterogeneities ingeological and topographical constraints have not beentaken into consideration in such analyses of material
circulations.
b. Future studies
There are limitations for any future studies that focus
solely on carbon and ice because of the insufficient
information relating to distribution, and it is therefore
necessary to begin by understanding the range of
uncertainties in the estimated amount. However,information pertaining to base materials is also quite
115

models. We consider that certain indications can beobtained from quantitative discussions. However, it isnecessary to develop a model that appropriately expresses
the carbon cycle of permafrost, and provides an ingenuous
way of defining valid boundary conditions. With
improved computing power, in the future we hope that an
approach using an Earth system model that combines a
climate model and a material circulation model will bepossible. In addition, we hope that with the accumulationof observational data, adequate information will havebeen gathered by that time, so that the full capacity of acomplex model can be exploited.

(from previous point-observations conducted at sites
using various methods) to multi-point observations, or towide-area evaluations using aircraft and satellite
observations. Furthermore, an understanding of thedevelopment process of permafrost over a time scale ofseveral tens of thousands of years accompanying glacial
cycles should be performed simultaneously with obtaining
the past history (Theme 3 Q2, Theme 6, and Theme 12 Q4).
To roughly define the maximum amount of carbon
stored in permafrost, an approach using a carbon cycle
model to estimate stored carbon amount in permafrost iseffective. However, since calculations are made over along time scale, studies are currently limited to simple

Q3: Warming and thawing of the permafrost: what is the process, and on what scale does it
happen?
(2) Thermokarst
As mentioned in the introduction, thermokarst forms
from the melting of permafrost and is accompanied bychanges in terrain. As it significantly changes theecosystem and hydrological environment of the ground’s
surface, we need to urgently gain an understanding of itsconditions and changes. In particular, it is important toevaluate the stability, spatial distribution, and melting
speed of the yedoma layer, as discussed below(Schirrmeister et al., 2013, and others). The yedoma layer
is found in the northeastern and northwestern parts ofEastern Siberia, and is a permafrost layer with extremely
high content of ice (volumetric ice content of 65–90%).
Furthermore, it has an extensive distribution, is asedimentary layer with a large organic carbon content, andhalf of its volume, or more, is occupied by ice. The
melting of the yedoma layer will therefore create a largescale thermokarst, and due to the warm climate of thecurrent interglacial period and the disturbance of theground’s surface caused by human activities and global
warming, a large amount of carbon accumulated mainly
during the ice age and fixed in the frozen ground willagain begin to circulate. It is thus important toquantitatively evaluate the impact of such an event.
However, as these permafrost layers are in remotelocations, the current conditions and changes in thegeographical and vertical distributions are not clearly
understood. Any changes in areas of permafrost with athermokarst add an element of large uncertainty to theprediction of climate change and changes in the polar
region.
Thermokarst is formed not only due to a deepening of
the active layer and a temperature increase in thepermafrost, but also in relation to erosion by waves andrivers. In other words, as the protocol of the abovementioned CALM and GTN-P alone cannot sufficiently
decipher the dynamic behavior of this phenomenon, it isnecessary to design a new observation system ( Theme
A: Monitoring).

a. The importance of research and its current state
The possible status changes of permafrost are discussed inthis section, and the topics are divided into those occurringin the active layer (Q3(1)) and the thermokarst (Q3(2)),
which are also related to the deep soil temperature ofpermafrost (Q3(3). To consider recent changes inpermafrost, in Q3(2) and Q3(3) it is necessary tounderstand the history of permafrost development over along time scale. Permafrost formed in the most recent
warm period (interglacial period) of over 10,000 years,
which exists in between several tens of thousands of yearsof repeated glacial periods in the paleoenvironment.
(1) Changes in the active layer
Changes in the spatiotemporal distribution of melting
parts of the active layer affect ecosystems andhydrological processes on the ground’s surface over a
relatively short time period. This is because spaces for theroot systems of vegetation and the biological activities of
microorganisms lie within the melting area in the active
layer of permafrost, and such areas regulate hydrologicalmovement. Changes in the active layer are not limited tochanges in the maximum melting depth (the thickness of
the active layer), but also present as changes in the timingof melting or freezing at the ground’s surface. Temporalchanges in the active layer due to global warming arecharacterized by an earlier melting and a delay in freezing.
Furthermore, along with changes in the ground’s surface
heat and water balance, there is an increase in the amountof heat entering the ground, and an increase in the
thickness of the active layer. Such seasonal changes in the
distribution of the active layer can also occur without any
long-term average changes in global warming, as they arealso related to changes in the amount and timing of
precipitation, and changes in time periods of snow melting.
The dynamic behavior of the active layer has a significant
spatial heterogeneity, and thus to understand the trend andthe cause of changes it is necessary to measure thechanges in temperature and soil moisture at the ground’s
surface (which includes the upper permafrost) on a highspatiotemporal density. However, excluding theobservation points that are specialized for a particular
distribution (such as CALM), such factors are currently
only monitored at one observation point, as in a supersite.

116

Figure 55: Predicted permafrost areas
until the end of this century (Slater andLawrence, 2013; IPCC AR5). Using the
published results of future climate
prediction by CMIP5, the monthly
average temperature and snow coveramount are bias-corrected and input toobtaindiagnostic
results.
Representative concentration paths(RCP scenarios) are color-coded. Thicklines represent the model means, andthe bands represent the variations
between the models.

The observational activities of TSP and CALM are
implemented by various research groups and projects(depending on the site), but long-term observations arestill rare due to limitations such as research funding andmanpower. In addition, monitoring activities are notstandardized over networks, and the methods ofmeasurement implemented are different depending on the
research organization: for example, important influential
factors related to changes in permafrost, such astemperature and snow cover depth, are not monitored at
all observation sites. Other discrepancies exist in thatobservation sites are usually concentrated in areas where
access and infrastructure are good. Research organizations
engaged in GTN-P have thus far conducted permafrost
monitoring many times, but due to various
implementation conditions at each observation site, andthe biased distribution of observation points as mentioned
above, it is difficult to make wide-area evaluations basedon measurement values related to the speed of changes in(3) Ground temperature changes in permafrost layers
The above-mentioned international observation
network, GTN-P, has been accumulating observational
measurements of ground temperature changes (TSP) andchanges in the active layer thickness (CALM). In the
Arctic region, the recent global warming trend is reflectedin an increase in the ground temperature of permafrost andthe formation of For example, according to Romanovsky
et al. (2010), the temperature of the depth at which theannual soil temperature amplitude disappears in Russianpermafrost has increased by between 0.5 and 2°C in thelast 20–30 years. In addition, melting of permafrost fromthe last ice age has been observed in areas of
discontinuous permafrost. It has been concluded that thesouthern edge of continuous permafrost has migrated
northwards, and that there have been changes in the
thickness of the active layer; it is increasing at someobservation sites although many sites that do not exhibit aclear trend.

Table 2: Prediction of rate of diminution of permafrost distribution area near the ground’s surface, and rateof increase in the thickness of the active layer until the year 2100 (Schaefer et al., 2012).

117permafrost (Schaefer et al., 2012).
Predictions of future changes of permafrost based on
numerical calculations have been reported by several
research groups. Figure 55 shows changes in the area of
permafrost based on the results of future climate
prediction (Slater and Lawrence, 2013; IPCC AR5). Thicklines represent the model means, and bands represent thevariations. Although the trends agree, if the variations in
scenarios of greenhouse gases concentrations (RCP) are
included, the range of uncertainties in the predictions
become wide, and the predicted values for the areas ofpermafrost at the end of this century show variations from
a 20% decrease to complete disappearance. Similarly,
Table 2 summarizes the rate of diminution of permafrost
distribution areas, and the rate of increase in the thicknessof the active layer near the ground’s surface until the year
2100, calculated based on the socioeconomic scenario
A1B (Schaefer et al., 2012). In each model, the expressionof land surface physical processes is different, and thepredicted temperature rise due to increased carbon dioxide
also varies; thus, these results also indicate that there is alarge variation in the predicted results (Koven et al., 2013;
IPCC AR5, 2013).

permafrost. In addition to monitoring the temperaturechanges of permafrost, research is to be progressed while
promoting the policy of the GTN-P. In addition, it isnecessary to fully determine international standards forthe observation methods employed. To avoid the influenceof limited access and infrastructure, the observation
support system needs to be strengthened and measurement
equipment requires development. Observation sites are to
be expanded to cover areas of permafrost where a largescale thermokarst is expected. There are extremely limited
examples of site observation measurements of land
subsidence areas and changes in the terrain due tothermokarst; thus, immediate implementation is required.
(2) Establishing a permafrost monitoring method
using satellite remote sensing
Changes in permafrost occur mainly underground, andthe spatial scale of the target area is in the order of meters;
thus, wide-area monitoring research based on satellites isdifficult. However, research on changes in the groundsurface conditions accompanying thermokarst can be
progressed significantly through the use of high spatial
resolution satellite products that will be provided in the
future. For example, some reports of observations of land
subsidence due to melting of permafrost by satellite radar,and products that give information on freezing andmelting of the ground’s surface are becoming moreavailable, and their future use is anticipated. To employ
these satellite data efficiently, the site observation design
and implementation period needs to be decided inagreement with the operation period and with themeasurement content of the satellite that corresponds to
the research objective.

b. Future studies
Changes in the condition of permafrost are not fully
understood yet, and neither can it be said that fluctuation
trends over wide areas are firmly understood. To
determine the rates of change, it is necessary to obtain thefollowing: the ground temperature profile as the initialcondition, the distribution of the amount of ice,
temperature changes as an external boundary condition,changes in snow cover, and any ground surface
disturbance. Simple observations are insufficient for all ofthese other than for temperature change. However, theimmediate challenge is to gain an understanding of current
conditions. Based on the following policy, monitoring
research will continue, although it is also necessary torealize future predictions through the development ofprediction models.

(3) Use of permafrost layer in the reconstruction of
paleoenvironment
The history of changes in permafrost is recorded in thepermafrost itself to a certain degree (see Theme 6). By
investigating past fluctuations, useful information canthus be obtained relating to future changes in permafrost.
If we move away from the conventional idea thatconsiders the upper layer of the ground’s surface in thepermafrost zone as a 2 layer-structure composed of anactive layer and permafrost layer, we can instead view thisas a 3-layer structure composed of the active layer,transition layer, and the permafrost layer (Theme 4, see
Q2), and identify the range of past changes inherent in theactive layer. Furthermore, when excavating deep layers ofpermafrost, undisturbed core samples can be collected andcomposition analyses conducted, in addition to making
measurements of ground temperature, for use inreconstructing the paleoenvironment.

(1) Strengthening site monitoring
The monitoring of ground temperature changes in theactive layer is to be conducted in detail to a depth which
includes both the transition layer (Theme 4: cryosphere,
see Q2) and the upper part of the deep permafrost layerthat will not melt within the next 100 years or so. Theseobservations will not only be limited to changes in the
thickness of the active layer, but observations of theseasonal distribution of the melting period will also be
increased. An observation design that takes measurements
willbeestablished,includingelementsofmicrometeorology that determine the changes of

Q4: Permafrost-Atmosphere-Snow-Vegetation system: what is its structure and behavior?
snow cover, hydrology, vegetation, and terrain (Figure 56,
Saito et al., 2013). For example, the atmospherictemperature needs to be below a certain point in order forfrozen soil to be formed. However, once frozen soil isformed it can withstand the warming of the atmosphere toa certain degree through the adiabatic effect of snow
cover, vegetation, and top soil organic layer (Shur anda. The importance of research and its current state
As already discussed in Theme 3 (Q2, Q3), Theme 4(Q2), and Q1–Q3 of this Theme, the dynamic behavior of
permafrost and seasonal frozen ground (i.e., theirformation, aggradation, maintenance, and degradation) is
influenced not only by the atmosphere at the time, but also
by the surrounding environmental conditions such as
118

such projects, and they both focus on quantifying thevulnerability of the permafrost environment. In Japan, as
part of the GRENE Arctic Climate Change Research
Project, quantification of the impact of terrestrial changes
on climate has been targeted through the coordination ofobservations and model research, and research exchanges
are currently being carried out between different projects.

Jorgenson, 2007). On the other hand, the existence of
permafrost limits biological activities and hydrologicalprocesses in the active layer (seasonal melting layer), andit affects vegetation on the ground. When the groundtemperature near the surface is kept low, thedecomposition of organic carbon is slow, and past organiccarbon is accumulatied in the soil as peat.
However, if an increase in the atmospheric temperaturesurpasses a certain level and is then maintained,diminution of frozen ground occurs in both vertical andhorizontal directions (for example, an increase in the
thickness of the active layer and a melting of undergroundice). This affects the surrounding environment bychanging the terrain and vegetation while potentiallyaffecting the areas outside of the Arctic by delivering a
release of greenhouse gases, an enhanced decompositionof soil organic matter, changes in albedo and the storageof groundwater, and changes in the transportation ofnutrient salts (inorganic carbon, nitrogen, phosphorus,
potassium, etc.) to rivers (Theme 3: material circulation,
Theme 4: hydrology).
It has already been long recognized that frozen groundis a component of a system consisted by interactions
between environmental factors as mentioned above(Francis et al., 2009). A number of interactions andfeedbacks (fb) between individual elements in thepermafrost–atmosphere–snow-cover–vegetation
subsystem have been studies previously (for example, thesnow-cover–radiation fb, snow-cover–vegetation (shrubs)
fb, greenhouse gases–temperature fb, and interactions
between changes in the ground surface layer due todisturbance such as fire–snow- cover/hydrology/frozen
ground, precipitation amount–forest fb; see Figure 56).
However, the understanding of the fundamental
behavioral characteristics od the entire system, such as thestrength and direction of the interaction between eachelement in the entire system, and the stability and its
conditions (i.e., which elements interact with which, whatis the strength and direction of the associated feedback andwhen it is stable, and whether a threshold and branchingexist for that stability) remain insufficient.
In particular, processes related to permafrost have awide spectrum in temporal scales. Some of them havelarge time constants, e.g., a glacial-interglacial timescale,
which are closely associated with material circulationsuch as deposition, storage, the decomposition of organiccarbon layers (such as the peat layer), and, consequently,
greenhouse gases. Therefore, those studies are limited that
explicitly deal with the processes and interactions of thepermafrost system at work from formation to degradation.
This all suggests that, for better understanding of thecurrent states and more realistic future projection of thepermafrost dynamics, it is inevitable to take thepermafrost system into account as a whole, not taking thepermafrost element out alone.
It appears that research communities in various
countries have simultaneously recognized this situation,and multilateral research projects on permafrost have thus
begun at almost the same time. PAGE2155 in Europe, and
RCN Permafrost56 in the United States are examples of55

b. Future studies
The dynamic behavior characteristics (size offluctuations, range of impacts, and their causes) of thewhole Arctic system, which is connected throughinteractions and feedback (atmosphere-snow cover-frozen
ground-soil-vegetation) on different time scales, cannot
simply be understood by examining each element
separately, or by looking at the interactions between eachindividual element. For a comprehensive understanding it
is necessary to use an approach based on dynamic systemanalysis. However, since we are dealing with an open andhypothetical system in the sense that the load and range ofmajor elements (and interaction of elements) change on
different spatio-temporal scales, we have to movestepwise according to the size, complexity, andspatiotemporal scale of the target phenomena at the time,
and take trial-and-error approaches at each step to broaden
our understanding. We should start from enhancementof observations, more appropriate presentation methods,
and the development of numerical models as proposed in
Q1 to Q3 avobe. Then, those observations and model
designs (numerical models, process models, ormathematical models for conceptual understanding) need
to be linked. As specific research subjects, the following
phenomena and time scales can be considered as
examples:1. The transition processes due to “disturbances” suchas forest fire (on a scale of 10–100 years). In
addition, the changes and recovery of near-surface
conditions (such as snow cover and temperature),
and vegetation on the surface and below ground on alandscape scale (of about 10 km or less).
2. The transition process during the Medieval Warm
Period, the Little Ice Age, and the “anthropogenic
warming period” (on a scale of approximately 1000
years), along with the covariability of “frozen
ground-hydrology-vegetation” on a regional scalethat accompanies climate change.
3. The retreat of coastlines and other changes during
the Holocene (scale of 20,000 years) associated withice sheet and sea-level changes since the last glacial
maximum, together with fluctuations in the cycles of
the “retreating ice sheet, exposure of ground surface
layer, growth of the frozen ground, formation of theground surface layer, and the deposition of peat”,
and “the marine transgression, submergence of
permafrost, formation and preservation of seabedpermafrost” in the Northern Hemisphere underlarge-scale climate change (global warming).
Although not included when referring to a scale of 10–
100 years (#1 above), the impacts of and on human andsocial activities (economy, design, and maintenance of

PAGE21： Changing permafrost in the Arctic and its Global Effects in the 21st Century

119

Figure 56: Linkages, flow, and feedback between components of the dynamic terrestrial Arctic system and the adjacentsubsystems (after Saito et al. 2013). [1] The land component consists of ‘‘land surface’’ and ‘‘ground’’ (subsurface) portions,and the internal exchange of energy, water and material. Interactions between [2] snow-permafrost, [3] snow-hydrology,
and [4] permafrost-hydrology. [3] Micro-topographical influences on those three components, and relationship between
physical and biogeochemical components are shown. The terrestrial system interacts with the overlying atmosphere ([AL]), oceans ([L-O]), and anthroposphere ([H-L]). [O-A] denotes the ocean-atmosphere interactions.

social infrastructure, and agriculture) should also be
considered in a similar manner, together with allinteractions with the biosphere (flora and fauna). Whenconsidering the system as a whole, various factors become
involved that have conventionally been handled indifferent academic disciplines; thus, a multidisciplinary
research system (for example the science of frozen
ground, climatology, soil science, geomorphology,
ecology, biology, mathematics, information science)
becomes necessary to identify the system at target, toextract central processes, to develop appropriate
observations and modeling strategies, and to implement
them. Currently, research projects on permafrost
fluctuations are in progress in Europe and the UnitedStates, and they focus mainly on the “frozen soil-carbon”
parts. However, progress is likely to be made in the
direction of grasping the system as a whole in the future.
The further promotion of international cooperation will
also become important in relation to information gatheringand joint studies, and will involve the sharing ofobservation sites and data, intercomparison of models, andmutual participation in collaborative projects.

120Chapter 8: Development of methods enabling breakthroughs in environmental researchefficiently conducting research and leading to the need forresearch infrastructure. We will overcome the handicap by
the complexity and difficulty of the data acquisition of the
Arctic, and contribute to the global scale study.

The pioneering breakthrough research is triggered byinnovative deployment of observation and modelingtechnique. Process research and monitoring of mutual
enlightenment, system modeling and data assimilation areimportant. We identify the current gap, as well as

Theme A: Sustainable seamless monitoring
Abstract

Greenland ice sheet and the mountain glaciers of the
Arctic Circle, coastal erosion and thermokarst associatedwith thawing and borehole management of permafrost is
essential. In the atmosphere, precise long-term
observation and understanding of the spatial variation of
atmospheric minor constituents involved in the climate,cloud and precipitation are essential. For the terrestrial
monitoring, maintenance and development of observing
stations (super site) overall to perform monitoring ofvegetation change, terrestrial ecosystems andmeteorological and hydrological observations, including
heat, water and carbon fluxes in the terrestrial sphere areneeded. With respect to these issues, monitoring
conducted by both in situ observations and remote sensing
is required. Here, we describe the monitoring initiative byclassifying areas into oceanic, cryospheric, atmosphericand terrestrial.
Q1: Oceanic monitoring
Q2: Cryospheric monitoring
Q3: Atmospheric monitoring
Q4: Terrestrial monitoring

Research monitoring of the Arctic environment has
been carried out as two elements, remote sensing,including the satellite and in situ observation.
Environmental change in the Arctic is important withregard to global scale influences; however, because of theseverity of the Arctic environment, in situ fieldobservations are hampered by the sparseness of observing
stations and subsequent large areas with no data. Although,due to recent progress, satellite monitoring has generated
new information, there are still many factors that need tobe observed in situ. The most important point ofmonitoring is to collect continuous, representative data.
International cooperation is essential to enable this;
therefore, Japan is also required to play a role.
As a matter of convenience, if the subject of monitoringis classified into the oceanic, cryospheric, atmosphericand terrestrial area, then the long-term priority issues thatJapan should tackle are as follows. For the ocean area, themonitorings of sea ice change, marine ecosystem andmaterial cycle through the year, with our own icebreakerand satellites are needed. In the cryosphere, determining
the mass balance and related various quantities of theIntroduction
The longer the time scale of change of the phenomenon,
the longer the time for which a continued period ofmonitoring is necessary. Continuous observation for morethan tens of years is necessary to understand changes inthe boreal forest, such as changes in the coniferous forest
zone and in the coverage of frozen ground.
Aspects that require long-term monitoring in the Arctic
vary widely. First, we outline the status and problems ofinternational networks for each monitoring case,subdivided into ocean, cryosphere, atmosphere, andterrestrial categories. Subsequently, future required
monitoring is described in detail. The Integrated Global
Observing Strategy on Cryosphere (IGOS-P Cryosphere)
has described the current status of monitoring in the Arctic,
particularly of snow and ice, and has provided
recommendations (Key et al., 2007). Based on these andother factors, we present a monitoring research initiativefor Japan to tackle.

It is important to continue long-term high-precisionobservation and monitoring. There is, however, a viewthat carrying out monitoring without defining a specificphenomenon of interest lacks conviction as motivation forresearch; however, there are many cases where one does
not know the universality of the phenomenon and where
the situation has only been observed in the short-term. By
observing over longer time frames (10 or 20 years), thephenomenon and related positioning of the situation may
become clear for the first time. A well-known example isthe increase in atmospheric carbon dioxide concentrations
recorded through precise observation data gathered by
Keeling in Hawaii; data gathering commenced in 1958,
with data accumulated over a long period of time,allowing the possibility of scientific evaluation (Keeling
et al., 1976). The sharp decrease in Arctic sea ice that has
occurred in recent years has been quantitatively clarified
based on satellite observations over more than 30 years.

Oceanic monitoringa. Monitoring of sea ice by satellite remote sensing
The most basic physical aspect of sea ice that isobserved from a satellite is the horizontal distribution ofice volume (concentration). Prior to satellite observations,sea ice distribution was estimated by collecting
information in the field. Satellite observation, notably
observation by microwave radiometers, began in the
1970s, and has allowed continuous monitoring of the

global sea ice area. As a result, we have been able to notechanges such as the reduction in sea ice area in the Arctic(Comiso and Nishio, 2008) (Figure 57). The current
mainstay of the microwave radiometer is the Japanese
AMSR series, and this is widely used for monitoring sea
ice. This is a sensor having the world's best performance,with about twice the resolution of the SSM/I, which was
the mainstay before the AMSR series.
121

understanding of the violent change state of the sea ice
surface (such as melt ponds); it would also allow
observation of all weather phenomena involved in sea ice
variations, such as a vortex at a scale of tens of kilometers.
With regard to the use of altimeters for measuring sea
ice thickness, for example, by also observing the ice
surface height in the direction perpendicular to the trackof current measurements, it would be possible tosignificantly increase observation frequency. To
understand the response of sea ice to climate change, itwould then be necessary to sustain such observations.
Furthermore, maximizing on the potential of existing data,such as high resolution images is the meaningfulequivalent of performing new observations. By
encouraging operational agencies and institutions tointegrate satellite data in different formats and to manage
and develop datasets, and by increasing the number of
researchers and engineers who use satellite data, the studyof the Arctic using such data can progress rapidly.

On the other hand, what is currently most urgently
needed is monitoring of sea ice thickness. The changing
characteristics of sea ice in terms of changing thickness
are not well understood, and even now, the representationof sea ice variability in climate models remains inadequate.
In order to estimate heat balance of the sea ice area andamounts of sea ice generation and melting (the basic
amount of sea ice change), and to understand the impact
of mechanical deformation of sea ice on thickness
variations, observation of the spatial distribution of sea ice
thickness is essential, as is monitoring of temporal change.
Spatial resolution is therefore expected to be less than orequal to several tens of kilometers, and ideal temporalintervals would be of a few days, or if possible, thethickness variation per day. Currently, in the United States(NASA) and Europe (ESA), surface height and ice
thickness are estimated by laser altimeter and radar,
respectively. These observations are expected to be usefulin future, but in terms of accuracy and frequency, they arestill not sufficient. There are also uncertainties relating to
aspects such as snow depth and it is necessary to estimate
the density of snow cover and sea ice. There is therefore
significant scope for future improvement.
In addition, observation is currently underway throughmany Earth observation satellites, such as synthetic
aperture radar and high-resolution visible observation
satellites. These high-resolution data are very useful todetermine the size distribution of ice floes and themechanical deformation of sea ice at a fine scale that
could not be captured through a microwave radiometer.
Furthermore, given the potential wide-area impacts of sea
ice change, the utility of this data could become moreevident in future.
The biggest priority for future microwave radiometermonitoring is to continue observation and to establish along-term stable monitoring system. Of high priority inthe maintenance of observation is the provision of highresolution data, which would make it possible tosignificantly improve its utility. Observation resolutionsof about 1–2 km would make possible detailed monitoringof the coastal thin ice area (coastal polynya) and of sea ice
distribution at the ice edge, as well as improving

b. Ocean monitoring under sea ice
In understanding the climate system, we urgently needto understand the mechanism of sea ice variability in the
Arctic Ocean that changes the heat balance between airand sea. So far, sea ice reduction has been mainly
observed in the vicinity of the Northwind Ridge of the
Pacific side of the Arctic Ocean, where warming issignificant due to Pacific water. However, changes in theseasonal sea ice area are now also occurring not only near
the Northwind Ridge, but also in waters where Pacificwater does not extend. Progression of the ocean seasonalsea ice area means an increase in area and expansion of
the period where there is contact with the atmosphere. As
a result, shortwave radiation and atmosphericdisturbances of the flow and vertical mixing of the ocean
surface, together with heat fluxes, can lead to a change in
the atmospheric field. Current and future heat balances
between the atmosphere, oceans, and sea ice are therefore
expected to differ significantly from those of the late
1990s, when sea ice was not as thin as at present and also
did not have such a small extent in summer. In other words,
in order to accurately predict future sea ice variability and

Figure 57: Changes in deviations in the northern hemisphere sea ice area, as observed by
microwave radiometer (from Comiso and Nishio, 2008).

122most of the insights gained in Arctic Ocean ecosystems
and material cycle research so far were based on
observation data gathered in open water areas in summer.
Because winter influences on ecosystems and material
cycles have not yet been well understood, we do not havea comprehensive understanding of related processes andvariations. Moreover, observations are biased in favor ofwater areas, with a focus on coastal zones to which accessis relatively easy; studies covering the entire area are veryfew.
In order to develop an overview of Arctic ecosystems
and material cycles, and to reveal changes and processes,
regional and seasonal differences must be taken into
account. It is physically and economically impossible fora single country to monitor in multiple regions and during
different seasons. Japan has performed a number ofobservations in summer in the Chukchi Sea and Canada
Basin region, using the "Mirai" and "Oshoro Maru",
linking ecosystems to material cycle changes. However,to understand the ecosystems and material cycle processof the wider Arctic Ocean, it is necessary to observe overa wider area; for this, international cooperation is essential.
We are currently noting the achievements of aninternational joint observation initiative, DBO, for which
Japan is also responsible (Grebmeier et al., 2010). In
future, it will also be important to strengthen therelationship with Russia and Canada, and to strategicallyobserve the Beaufort Sea, Canada Basin, Chukchi Sea,and East Siberian Sea (Figure 58). Through international
cooperation in the Arctic Ocean, it will be possible toensure highly accurate and multiple marine monitoring
observations, examples of which are provided by WOCE,
performed over a single ten-year scale. In addition, toensure efficient data operation, it is essential to cooperatewith international data organizations such as the World
Data System (WDS), and to aggregate and release active
metadata.
Japan’s Arctic Ocean observations have so far been
limited to open water areas in summer. This alone is not
sufficient to understand the material cycle and ecosystemchange. It is important that, as part of international
cooperation at appropriate locations (for example, a blankarea of observation such as the Canada Basin and ChukchiSea), Japan also establishes a research icebreaker that canallow for winter observations in future, thus being able tocarry out observations of material cycles and ecosystems
that include seasonal variations. In addition, fulladvantage should be taken of recent advances intechnology, such as in mooring systems and remoteobservation technologies (for example, in audio
equipment and underwater gliders), particularly in the
Arctic Ocean where access is not easy. Above all, because
mooring systems are a powerful tool for year-roundobservation of organisms, it is essential to install multiple
mooring systems in appropriate waters throughinternational cooperation. Satellite data is also an
important tool for understanding spatio-temporalecosystem and material variations. It may be necessary to
conduct high-resolution long-term monitoring of sea ice,snow and ice, and ocean color. The planned launch of the
AMSR2 successor machines and Sentinel-3A • PACE
stems from the very fact that these provide an important
foundation for observations aimed at understanding
space-time variability of ecosystem-related parameters;
we strongly hope that such a regime is established andmade available with ease to many researchers.

impacts on the climate system, it is essential toquantitatively clarify each physical elementary process ofthe ocean surface mixed layer from the atmosphericboundary layer, not simply during the melting period but
rather during the ice season (winter), and the contributionof these to sea ice variability. However, Japan's past Arctic
Ocean observations, carried out using its own ice classvessels or other countries’ icebreakers, took place during
specific observation periods, with related constraints ofobservation time, waters, personnel, budget, etc. On theother hand, sea ice-mounted drifting buoys are deployed
and gather observations throughout the year. However,there is a bias in the spatial distribution of data frequency
because of the fact these are installed only in thick sea ice
areas and because the observation area is dependent on sea
ice movement; it is therefore not possible to observe thesame area over a period of time. Moreover, because
mooring system observations are designed to avoid
multiyear ice, instruments cannot be installed from thesurface to about 50 m depth, and measurements are
difficult (with the exception of measurement of flow rate).
Here we propose carrying out "ice season - winter air –sea ice heat balance observations" using our own national
icebreaker; such observations would be difficult using ice
class ships or icebreakers belonging to other states. We
would specifically deploy field observation (including
over ice) by the icebreaker and manned observation
stations in the Northwind Ridge ~ Makarov Basin of the
Pacific side of the Arctic Ocean, where seasonal sea icechanges are already recorded, considering the heatbalance of air - sea - ice during the ice season over a wide
area of ocean. In addition, the fixed point will beestablished within the sea ice reduction area, with heatbalance observation of air - sea - ice through icebreaker
winter observations. Such data can quantitatively reveal
sea ice movement in relation to the heat budget process of
air - sea ice - ocean, ocean tides (internal waves), and thecontribution to heat transport of atmospheric disturbancesand freezing and thawing processes. In addition, throughwide area observation using existing ice class vessels andthe deployment of unmanned observation stations(mooring systems, drifting buoys, etc.) during the melting
season, thus revealing the heat content of the ocean
surface in open water, we can determine time variations in
the ocean mixed layer and preconditions before freezing.
In this way, based on the time difference between
icebreaker and ice class vessel observations, theelementary heat balance processes between air - sea - icecan be revealed year-round.
c. Monitoring of marine ecosystems and material cycles
Marine ecosystems in the Arctic Ocean are unique,composed of species adapted to low temperatures and to
the sea ice environment. Drastic reductions in sea ice
and a summer increase in water temperature that havebeen observed from the 1990s suggest the potential
likelihood of significant change in Arctic Ocean
ecosystems and in the related material cycle. In addition,
since global warming over the 100-year scale causes
melting, not only of sea ice but also of permafrost and ice
sheets on land, it increases the amount of freshwaterflowing into the Arctic Ocean and greatly changes
material cycles and coastal ecosystems. It is therefore very
important to efficiently monitor the ecosystems andmaterial cycle surrounding the Arctic Ocean, and toquickly understand the changes taking place. However,123

In addition, freshwater and material supply from land is
deeply involved in changes in the marine ecosystem andmaterial cycle. The coastal areas where many organisms(ranging from large mammals to benthic organisms) live
are hot spots of the Arctic Ocean ecosystem. In order tounderstand environmental changes in coastal areas, it isnecessary to strengthen interdisciplinary cooperation andto construct a system to deploy seamless monitoring
observations from rivers to the ocean.
d. Monitoring of radiation fluxes of the sea ice area
In the heat balance of the Arctic, shortwave andlongwave radiation fluxes play a very significant role. The
heat balance of the entire atmosphere of the Arctic northof 70 ° latitude is estimated as the sum of net shortwavelongwave radiation fluxes at top of the atmosphere, heat
fluxes transported from the mid-latitudes to polar regions,and the influx of the heat flux from surface processes,
including sea ice freezing/melting. It is a net longwave
radiation flux that contributes most to the heat budget inabsolute terms throughout the year. In particular, thisbecomes a dominant factor in winter when shortwave
radiation is lost. In summer, shortwave and longwave
radiation contribute to the same degree, and it can be said
that both play an important role in the heat balance of the
Arctic.
On the other hand, when we focus on the heat balanceover the surface that is directly related to growth andmelting of sea ice, excesses or deficiencies that occurredin the net radiation flux on the surface are basicallycompensated for by the turbulent flux (sensible heat flux
+ latent heat flux) and conductive flux through snow andsea ice, or by the latent heat of fusion of snow and sea iceon the surface. This indicates the importance of accurate
measurement of shortwave-longwave radiation fluxes for
estimating growth and melting of sea ice (Serreze et al.,2007). However, because of logistical difficulties in polar
regions, the data obtained from long-term monitoring
observation has been very limited. Since 1992,
observation of the radiation flux in the Arctic has takenplace at three locations, covering a relatively wide area:
Barrow (71 °N latitude), Ny-Alesund (79 °N) and Tiksi(72 °N); this has been done through BSRN, affiliated to

Figure 58: Elements necessary for future monitoring ofmarine ecology (conceptual diagram).

WCRP. We strongly expect to maintain and reinforce
these observation systems in future.
Cloud is another important factor affecting the surface
radiation balance in the Arctic Ocean. Observations
derived from SHEBA (see footnote 11) show that the net
longwave radiation flux at the surface has a negative value(upward), ranging from -20 to -40 W m-2 throughout theyear, and that the downward longwave radiation flux
contributes most to variation, with the presence or absenceof clouds making a particular difference by more than 70
W m-2. The cloud fraction (particularly of stratus clouds
appearing in the lower layer) is therefore considered to be
an important component, requiring continued long-termmonitoring in the Arctic region, in conjunction with
monitoring of shortwave and longwave radiation fluxes.

Cryospheric monitoringice sheet are very important (e.g., Steffen and Box, 2001).
In order to increase the accuracy of mass balancemonitoring over the entire ice sheet, there is a need formore intensive satellite and field observations, greaternumbers of automatic weather stations, data to fill in blankareas, and long-term maintenance of facilities.
On the other hand, snow and ice surface albedo is oneof the most important factors for surface melting. Ice sheet
surface albedo in the accumulation area depends on snow
grain size and light-absorbing aerosols included in snow
(black carbon and dust), while it is also greatly dependent
on the concentration of snow and ice microorganisms in
the ablation area (Wientjes et al, 2007). For this reason,
there is a need to carry out, in sync with albedo monitoring,measurement of light-absorbing impurities in snow coverin the accumulation area, pit measurement of snow
particle size, snow and ice microbial sampling, andcryoconite observation in the ablation area. In addition,
there is a need to perform shallow ice core drilling in

a. Meteorological and glaciological observations andmonitoring of light absorbing aerosols and cryosphericmicroorganisms on the Greenland ice sheet
The total mass balance of the Greenland ice sheet isdetermined by the accumulation rate, surface ablation rate,and ice discharges from calving glaciers. Ice sheet surface
elevation is determined based on these mass balance
processes and ice flows. Recently, ice sheet surface
elevation has been accurately measured by satellite laser
altimetry. Moreover, mass changes in the ice sheet havebeen measured by monitoring the gravitational field using
satellites, and reduction in ice mass in recent years has
become apparent. Glacier flow and ice discharges from
calving glaciers can be observed by satellite, but local
observations are still required for understanding theinternal structure of the glacier (ice thickness, bed
elevation), and also for detection of changes inaccumulation and ablation rates. For this reason,
observation by automatic weather stations installed on the124to-year depending on meteorological conditions.
Available information derived from short-term orintermittent observations is therefore limited, and it isimportant to perform continuous measurement over a long
period of time. Currently, continuous mass balancemeasurements in Greenland are limited, but organizedobservational networks are growing through PROMICE,
led by Denmark.
In future, in order to increase mass balance data for theGreenland ice sheet, mountain glaciers, and ice caps
distributed over the Arctic, worldwide cooperation will benecessary. It will be important to contribute to the global
Arctic research community by establishing areas that arestudied by the Japanese and by providing the data acquired.
Specific monitoring target areas include northwest
Greenland, where observation started through the GRENE
project. Data will be gathered for various locations, from
calving glaciers on the coast to the inland ice sheet, as well
as for independent ice caps. Research activities in thisregion hold promise for future development andcontinuation. To measure mass balance over an extended
period of time, it will be necessary to continuously ensurethat there are the personnel and budget to perform fieldmeasurements in remote areas. For long-term
observations, we should also consider training local
collaborators.

various places to reconstruct, with high temporal
resolution, light-absorbing impurities and microbialconcentrations of the past, including seasonal variations.
b. Long-term observation of the mass balance andmeteorology of pan-Arctic mountain glaciers
In the study of glaciers in the Arctic, understanding ofmass balance change is important. Despite the fact that the
Arctic is strongly influenced by the recent warming trend,
there is less glacier mass balance data than in other regionsof the world (Vaughan et al., 2013). In future, it will benecessary to collect long-term data through methods suchas in situ observation and satellite imagery; there is also aneed to cooperate with other countries (refer to Theme 4
and the next section, "Continuous observation of the massbalance of the Greenland ice sheet and of glaciers and ice
caps on the peripheral edge").
The following can be considered key elements of afuture research strategy for Japan: ① initializing new
observations in areas where there is no glacier observation
to date, ② resuming glacier monitoring where data wasgathered in the past, and ③ cooperating in the monitoring
conducted by other countries. Below, we describe thecurrent status and potential for future study in Arctic
countries and regions where glaciers are present andwhere observations are required (Canada, Alaska, andRussia). In Alaska and Canada, the contribution of glaciermass loss to sea-level change is large. In this region, there
is missing observational data for glaciers that are
logistically difficult to approach, e.g., Brooks Range. In
the islands of the Canadian Arctic (such as Ellesmere
Island, Baffin Island, etc.), observations were initiated a
relatively long time ago, but long-term mass balance data
is insufficient. In Russia, there is no glacier mass balancedata for recent times, even in the case of glaciers that werestudied in the past. In addition, although meteorological
data are relatively abundant for the period of the former
Soviet Union, in recent years there has been a rapid
decline in such data.
Together with mass balance observations, it isnecessary to observe meteorological components that
determine mass balance. In the case of suchmeteorological observations, there are maintained
databases, such as that of NOAA. For re-analysis data,
differences between observed values in the Arctic arelarge, and it will be important to ensure further
improvement in future. Since instruments are difficult to
operate in low temperature environments, it is important
to develop more robust ones. More frequent and detailed
maintenance of instruments is as important as having awell-organized research plan. To improve the efficiencyof observations, it will be necessary to hold workshop
discussions on meteorological observations in the Arctic,
as well as to cooperate with other countries.

d. Long-term observations of glacier and ice sheet
fluctuations by satellite
Given recent developments in satellite observation
technology, in addition to basic information such as theglacier terminus position and its area distribution, it is now
possible to observe many different aspects of glacierfluctuations. Important observations specifically include:① measurement of the glacier terminus position and area
through visible and microwave images, ② measurementof ice volume change by stereographic photogrammetryof visible images and by altimeter data (e.g., Bolch et al.,2013), ③ measurement of ice flow speed through image
correlation and interferometric synthetic aperture radar(InSAR) (e.g., Moon et al., 2012), and ④ measurement of
ice mass changes by gravity measurement. For future
monitoring of Arctic glaciers and ice sheets, it will be
important to utilize and develop these data andtechnologies.
For ① , higher resolution imagery is now available at ahigher temporal resolution. In future, using techniquessuch as automatic extraction of the glacial periphery, we
will need to process a large number of images over agreater area.
Method ② is a conventional technology. Accuracy has
been improving thanks to recently-available highresolution images, and the importance of this method has
increased. In stereographic photogrammetry using visible
images, further results can be obtained by improving
automatic DEM generation computer algorithms. In
addition, we need to continue accurate monitoring throughaltimeter measurements, as represented by ICESat ofNASA, over a wide area of the Arctic.
For ③ , there has been excellent progress in studying
calving glaciers on the Greenland cost, where ice motion
plays a major role in glacier fluctuations. Higher temporaland spatial resolutions can be achieved in future bydeveloping next-generation satellites and improving data
analysis techniques.
④ is a new technology that emerged over the pastc. Continuous observation of the mass balance of theGreenland ice sheet and of peripheral glaciers and ice caps
When measuring mass change of glaciers and ice sheets,
surface mass balance is one of the most importantparameters (see Theme 4). In recent years, althoughsatellite observations are underway, it has been difficult tomeasure accumulation and ablation rates from satellite
data. Field mass balance measurements are also importantfor validating satellite data and better understanding
mechanisms of elevation change. Snowfall and melt are
responsible for mass balance, and they vary greatly year125

formed by ground surface depression due to the thawingof permafrost (see Theme 12 with respect to theprogression of thermokarst). As well as being due toclimate change, thawing of such frozen ground is also
caused by a disturbance to ground surface conditions, suchas loss of vegetation due to locally-occurring forest fires
causing a rapid increase in the active layer thickness ofpermafrost (Viereck et al., 2008), resulting in rapid
formation and development of thermokarst. Because
formation of thermokarst can lead to changes in thesurrounding water environment, long-term monitoring of
distribution and variation is needed.
In continuous-discontinuous permafrost zones around
Alaska and Siberia, it is therefore necessary to understandthe distribution of current thermokarst using local
observations and satellite data. Thawing of permafrost
appears as an observable phenomenon, and this data
provides a basis for understanding future fluctuations.
Understanding the cause of frozen ground thawing in eachregion and understanding variations in local conditions
will contribute to long-term environmental change
prediction.

decade through GRACE satellites, providing new
possibilities, particularly in the measurement of ice sheet
mass variation. We expect development of a data analysis
method to allow for accurate monitoring of, not only theGreenland ice sheet, but also mountain glaciers and ice
caps over an extensive area. In any of the cases describedabove, there has been significant innovation both insatellite sensors and in data analysis techniques. In
addition to using available new technologies, those who
study glaciers and ice sheets are expected to provide ideas
for future satellite observations and technicalimprovements. This will ensure the development ofsatellite observations and technical improvements fornecessary Arctic glacier and ice sheet research. With
regard to maintenance and sensor development of satellite
observations, refer also to the description given in Chapter 9.
e. Monitoring of quantitative changes in snow and ice
distribution, cloud distribution, and snow and ice
microbial distribution and quality changes (such as
snow grain diameter and albedo) by satellite
In addition to collecting observations using an artificial
satellite as described in d., it is important to monitor darkareas covered with snow and ice microorganisms within
the ablation area of the Greenland ice sheet, particularly
since these have expanded in recent years (Wientjes et al.,2007). In addition, even for surfaces covered with snow, it
is important to monitor qualitative changes, such as
aspects of snow physical quantity and temperature related
to albedo (e.g., snow particle size and light-absorbing
impurity concentrations), as well as changes in albedo
itself using satellites; this is crucial from the viewpoint ofunderstanding albedo feedback mechanisms, and formodel development and future prediction. Technicaldevelopment is therefore important for extracting, withhigh accuracy, those snow physical quantities from themulti-wavelength imager satellite having a channel in thevisible and near-infrared regions (Hori et al., 2007).
Because the presence of clouds in the Arctic is an
important factor for radiation balance, it is also necessary
to monitor, in the long-term, information such as cloud
distribution, cloud particle size, altitude, and thickness,using satellites.

g. Monitoring changes in coastal erosion andunderground ice of the Arctic Ocean
A large amount of underground ice exists near the
ground surface of the coastal Arctic Ocean (yedoma; seeBox 8 in Theme 12). The process still underway involves
topsoil flowing out by coastal erosion, initiating thawing,with subsurface ice exposure then proceeding; risingtemperatures and sea level rise are expected to accelerate
this process. This yedoma ice has been shown to containa large amount of methane (e.g., Fukuda, 1993). Because
thawing results in the release of carbon fixed in permafrost,
there is also the potential to contribute to an increase ingreenhouse gases. On the other hand, the thawing ofunderground ice causes the collapse of the ground surface,with direct impacts on human life arising from, forexample, the collapse of buildings and coastline retreat. In
some areas, such cases have led to movement of a wholecommunity (Shishmaref, Alaska). However, there are no
examples of temperature measurement of yedoma itself.
Against this backdrop, the importance of monitoring
the progress of coastal erosion, variations in the coastline,
and underground ice variability is high. Together withfield surveys (that include temperature measurements ofyedoma not carried out so far), it is therefore necessary toperiodically monitor coastline variations using aerial

f. Understanding and long-term monitoring of the
distribution of thermokarst due to the thawing of
permafrost
In the permafrost zone, thermokarst topography isBox 9 Observations of glacier mass balance
Glacier mass balance can be measured through field observations (surface mass balance, front
position, etc.), satellite imagery analysis (mass change, area change), and so on. Direct fieldobservations are preferred for accurate measurement but remote sensing techniques using avariety of satellite data are effective to cover broader and remote areas. With regard to the latter,more extensive use of GRACE satellite data is expected. For small glaciers and regions where
greater error is expected in GRACE data, mass change can be more accurately estimated from areaand elevation changes measured by satellites such as ICESat and ASTER. In addition to direct
observations in the field, records of glacier terminus position can also be utilized for the study.
Observations of terminal position have been carried out at about 500 world glaciers (Vaughan etal., 2013).

126

evaluate human impacts on climate change. Against thisbackground, it is necessary to install long-term sustainableboreholes in the Arctic, centered on Alaska, Canada, andSiberia. In recent years, this has taken place through the
GTN-P 57, led by the International Permafrost Association(see also the description of Q3 in Theme 12 with respect
to variations across the network and in measured values).
In this project, a blank area of the existing network ispreferentially selected as an observation point. The target
is to have 100 additional observation points.
For the installation and maintenance of drilling holes insuch areas, cooperation with local research institutions isessential, making it necessary to maintain and and develop
existing and new cooperation, respectively. As an example,
the International Arctic Research Center (IARC) at the
University of Alaska Fairbanks, has established acooperative relationship with Japan over a long period oftime. In addition, there are many researchers in the IARC,
including Japanese, Canadian, and Russian, who occupy
important positions, even through joint research withthese countries. It would be effective to prepare, install,and maintain borehole observations using the IARC as abase, enabling long-term soil temperature observation.

photos obtained by airplanes and satellites. In particular,
in regions with wider distribution of underground ice, it isnecessary to evaluate the rate of progress. It should be
noted that there is a possibility that yedoma ice can betaken full advantage of for environmental restoration
purposes (see Theme 6).
h. Monitoring of permafrost temperature state byborehole observation
Soil temperature provides very basic information
concerning the permafrost environment. Although there
have been soil temperature observations by borehole tovarious depths and for various purposes in countries of the
Arctic, the maintenance environment varies, even having
unknown abandoned sites. Maintenance by installing
drilled holes for long-term temperature measurement
allows for long-term monitoring of the temperature stateof frozen soil in the Arctic, and is important in order toconsider the response of frozen soil to climate change.
With regard to soil temperature variations, since themeasuring depth is deeper, there appear to be longer timescale variations (with time difference) and it is important
to maintain deep borehole observations even in order toAtmospheric monitoringa. Importance and status
With regard to greenhouse gases and aerosols, longterm continuous monitoring has been conducted that is
broadly representative of the Arctic, with monitoring at
Barrow (Alaska), Alert (Canada), and Ny-Alesund(Svalbard) contributing to estimation of transportmechanisms and of sources and sinks, as part of a global
observation network. However, there are no observation
points along the vast Siberian coast facing the Arctic
Ocean, with placement of observations thus being biased.
Furthermore, most of the observations have been made at
ground bases. Although flight-based observations, such as
through aircraft, have been conducted in Alaska andaround Svalbard, there is still very limited observed datafrom the middle-upper troposphere. Monitoring ofgreenhouse gases is required to continue in the long-term,in particular through high-precision observation, and it isnecessary for support to be provided through international
cooperation.
Meteorological phenomena and atmospheric minor
constituent (greenhouse gases, short life gas, aerosol)changes not only respond to changes in the surrounding
environment, but via a radiation process, influence theclimate (for short-lived gas, see footnote 15). The Arctic
is divided into a sea ice area (which accounts for most of
the Arctic Ocean), an ocean area (with vast biologicalproduction volume), and a land area (including the vast
permafrost zone, the forest zone, and the industrial area,
also extending into the Arctic Circle); these incorporate
processes, sources, and sinks of atmospheric minor
constituents. Although secular temperature changes fromthe early 20th century have been observed, we havefocused mainly on studying variable factors, as comparedwith factors such as sea ice distribution and ice core data
(e.g., Yamanocuhi, 2011).
Secular changes in precipitation have different trends
depending on region and cannot therefore be explained in57

terms of a simple increase or decrease. Current
precipitation data for the Arctic is based on sparse rain
gauge data. In recent years, discharge of large rivers
flowing into the Arctic Ocean is said to be on the increase,and a change in discharge is likely due to changes inprecipitation. However, due to the problem of low
observation point density for precipitation data and to thecatch ratio of precipitation gauges for snowfall, we cannot
quantitatively describe the discharge increase. Use of
artificial satellites is expected to contribute mostly tounderstanding the spatial distribution of precipitation.
Previously, valuable data were acquired by TRMM in low
latitudes. On the other hand, for middle and high latitudes,
we have no continuous rainfall observation system to date.
The main satellite of the global precipitation observation
program (GPM) was launched in 2014, following muchanticipation. However, high precision observation isdifficult for snow.
For greenhouse gases (CO2, CH4, N2O, etc.), the yearto-year increasing trend and secular variations in growthrate have been confirmed. In addition to the effects ofglobal-scale human activities, the impacts of CH4
emissions from wetland areas have also been noted (e.g.,
Morimoto et al., 2006). In the case of ss-SO42- and black
carbon (BC) in aerosols, year-to-year decline has been
observed, resulting from reduced emissions since the1980s. However, since for a part of the aerosol component(NO3-) and scattering coefficient, such a decline has notbeen observed (or more recently, an increase has been
noted) (Quinn et al., 2007), the possibility of long-distancetransportation from the low and mid-latitudes has also
been discussed (for BC, see footnote 14). Satellite data haspointed to an increase in the distribution and secularchange of clouds, which may significantly affect theradiation balance; however, there is still a large degree of
uncertainty (e.g., Wang and Key, 2005) (for the
relationship of aerosols and clouds, see footnote 18).

GTN-P: Global Terrestrial Network for Permafrost

127

Figure 59: Elements necessary for future monitoring of atmospheric minor constituents(conceptual diagram).

are experiencing; this would allow us to not only discuss
long-term variations but also changes at minute, date, orseasonal scales.
In areas where observation bases are very limited (suchas the Arctic sea and Siberia), we are going to establish
meteorological observation sites, with the aim of longterm operation through an observation network. In
particular, we would like to see the establishment andmaintenance of an aerological observation network inorder to understand long-term fluctuations in basic
meteorological parameters in the atmosphere (temperature,
water vapor amount, and so on). Precipitation is a basic
water balance quantity and we need to understand its longterm spatial and temporal variations. We should not onlyuse ground-based observations, acquire and use global
satellite precipitation radar data, and make full use of data
assimilation techniques, but we should also acquire highsophistication precipitation data. To do this, it is necessary
to build a cooperative relationship with experts in fields
such as remote sensing, radar, and data assimilation. For
ground-based observations, as well as to improve wintersnowfall observation technologies, we aim to maintainand increase observation points.
For greenhouse gases, we aim to maintain the current
monitoring observation system, while adding a newobservation point and capturing long-term concentration
changes. In addition, there is also a need to continue tomaintain and develop high-precision observations ofisotopic ratios, with information about the source and sinkof greenhouse gases. In addition to understanding
emission increases due to the abrupt expansion of humanactivities in the Arctic Circle (based on the fact thatchanges in fluxes due to Arctic environmental change are
expected), knowing the flux of greenhouse gases interrestrial and marine areas is important. In addition todata near the ground, we can utilize aircraft observations
and satellite data to understand three-dimensional space-

These secular changes are related to other complex
elements, for example, the relationship between various
northern hemisphere processes and global-scale, humanactivities, and terrestrial and marine environmental
change in the Arctic. In order to detect long-term
environmental changes in the Arctic, long-term
observation and observation system maintenance formeteorology and key atmospheric minor constituents are
essential. However, at present, due to observation
limitations and difficulties, there are still frequent blankperiods and regions of observation data. Scientific dataobtained in the past does not extend far enough to allow
for understanding of environmental change in the Arctic.
b. Future research
Much long-term observation and research in the past
were based on observations conducted near the groundand on routine meteorological observations fromobservation sites. In order to detect long-term variations
in Arctic environments and to validate processes, inaddition to long-term observation of basic parameters, it
is important to understand space-time change and theactual situation. Basic parameters are temperature,amount of water vapor, precipitation, greenhouse gases,
short-lived gases, clouds, and aerosols. Because the lifetime of these parameters in the atmosphere varies widelyin scale, from seconds to years, it is necessary to change
the observation frequency and measurement resolution,
depending on the phenomenon and process of interest. In
order to examine the relationship between Arctic
environmental change, climate change, and changes inmaterial dynamics of the atmosphere, it is necessary tounderstand variations on scales of several years to several
decades. It is also important to capture elementary
processes at any short time scale (such as sources, sinks,etc.) of atmospheric components associated withenvironmental change, as well as long-term changes they128

variation, it is also important to periodically deploy
observations using ships, aircraft, and other flight craft,
and to verify the physical and chemical properties ofclouds and aerosols in each area (optical properties,
number concentrations, size distribution, composition,etc.) and spatio-temporal variations and trends in shortlived gases. Furthermore, we can also use satellite data to
track spatial variation in distribution of clouds andaerosols.

time variation in greenhouse gases.
For observation of short-lived gases, clouds, andaerosols at bases where long-term monitoring is
performed, it is desirable to maintain continued
observations; it would also be useful to provide amonitoring center by establishing an observation base inareas for which long-term observation data has not beenobtained (Arctic Ocean, Siberia). Since short-lived gases,
clouds, and aerosols have intense spatio-temporal

Terrestrial monitoringb. Long-term continuous observation of meteorology,
flux and vegetation phenology
In the past, various meteorological stations have been
deployed, and development of wide-area grid data has
been advanced by using these in several institutions (e.g.,
CRU data and APHRODITE precipitation datasets).
However, the area where meteorological data etc. can be
widely used is limited; in Siberia, for example, thenetwork of observation stations is sparse compared toother regions. Development of meteorologicalobservation networks and observation data in these areas
is important.
Ground tower observations of heat, water, and carbon
fluxes are the most directly relevant monitoring aspects
for understanding spatio-temporal variations in heat,water, and carbon balances. To measure global water, heat,and carbon fluxes, a ground observation network called
FLUXNET has been in use since the 1990s. Althoughmore than 500 sites in the world are currently registeredin FLUXNET, there are 10 sites (each) in Alaska and in
the Nordic area, and only about 5 sites in Siberia,
notwithstanding the latter’s vast area. Even though the
Arctic is an important area for the Earth’s carbon cycle
and heat balance, given the severity of its natural
conditions and low population, observation point density
is sparse at present. An observation site in east Siberia(Yakutsk suburbs) was established through the GAME
project in 1997 and is one of few sites jointly maintainedby Japan, Russia, and the Netherlands. Flux data isnecessary and essential for validating land-surface
models; from this perspective, so-called super site specificground-based observations, where observations ofmeteorology, snow and ice, hydrology, vegetation, andsoil are carried out at the same point, are important.
Moreover, it is critical to have river basin discharge
observations (including at the observation site); these areimportant for verification of water balance. Long-term
variations in the land surface and vegetation environment
have been considered to be strongly influenced by soil
temperature and soil moisture, and continual observationof these parameters is also important. There are presently
only few super sites, such as Yakutsk and Fairbanks in the
Arctic, and there are challenges in terms of development
and maintenance of long-term comprehensive observationsites (see also Theme 4).
For observation of fluxes, previous studies havefocused on relatively short-term fluctuations, such as
seasonal variation. In recent years, there has been moreemphasis on detecting inter-annual variability, and sites
with an observation period of more than ten years haveincreased. We are now attempting detection of trends often or more years duration. These long-term observations
allow for detection of, for example, the carbon balancea. Long-term and continuous observation of theterrestrial environment using the same satellite formore than a few decades
Data from AVHRR sensors onboard the NOAA
satellites is the most widely used long-term data (morethan 30 years) for vegetation change analysis atcontinental and global scales. These data sets enable us toanalyze and detect extension of vegetation growing
seasons and changes in vegetation photosynthetic
activities responding to climate changes (e.g. Suzuki,2013). The NOAA AVHRR data contains large
uncertainties in terrestrial signals due to effects such as
replacement of sensors and satellites, orbital drift, anddifficulties in atmospheric correction. On the other hand,
the improved atmospheric correction and observation
wavelength bands of recent satellite observations such as
SPOT / VEGETATION (observation period: 1998 topresent) and Terra / MODIS (observation period: 2000 topresent) provide better quality data compared with NOAAAVHRR. This observation data covers a 10–15 year
period, and through continuous future observation, it isexpected to be possible to detect changes and trends invegetation amount and activity.
In recent years, there has also been frequent vegetation
monitoring using a spaceborne L-band microwave
synthetic aperture radar such as ALOS PALSAR (SAR).
SAR data are quite useful for estimating abovegroundbiomass in the boreal forest and have been widely applied.
This is because aboveground biomass in the boreal forest
is much smaller than in tropical forests and the backscatter
intensity from SAR is not saturated in the boreal forests.
Long-term observations by the L-band microwave SAR
are expected in future.
In terms of the importance of change detection overlonger time scales, it is important to construct satellite
observation networks aiming at long-term observation of
more than ten years at a minimum. For example, theobservation satellites planned in Japan need to be
developed from the perspective of needing long-term
observation, including by planning successors.
In recent years, we have not only seen the development
of data products of surface biogeophysical parameters as
satellite projects, but it has also become possible toprovide various biogeophysical parameter products ateach individual study group level. In addition, integrationof multiple satellite data provide the possibility of
producing better products, by maximizing the advantagesof data from each individual satellite. It is important toconstruct a base for building these biogeophysicalparameters in individual groups, even without
participating in satellite product development projects.

129and using satellites, also focusing on isotopes.

change due to climate (Ueyama et al., 2014). In future, it
is expected that the number of observation sites wherelong-term observation is possible also increases bycontinuing current observations, allowing for continued
improvement of the reliability of trend detection.
Furthermore, in areas where large variations in the carbon
balance are expected, such as where variation tendencies
are accelerated by future climate change, it will benecessary to develop a monitoring network for early
detection of these variations.
For vegetation phenology, observation networks arebeing deployed, such as those of PEN 58, performing fixed
point photography of forest landscapes by fisheye lenscameras. However, there are only very few observationsites at present, and more sites across a wider range areneeded. Further, by carrying out trend analysis on thetiming of variation, such as by using leaf indicators, it will
be possible to detect variation signals at more sites.
Moreover, through fusion with satellite data, we expect tobe able to scale up results to discuss the phenology
information of a wider area.

e. Accumulation amount of carbon (biomass, soilorganic matter)
Monitoring of carbon stocks is also important, together
with flux measurement. In particular, carbon content insoil is likely to be released with future climate change,
making it important to estimate the size of such potential
carbon emissions through a more reliable estimate ofbiomass. As pointed out in the section on cryosphericmonitoring, thawing of permafrost has been strongly
involved in processes such as methane release. Sincechanges in frozen ground vary greatly by region, detailed
monitoring is required. In addition, the release of methaneis also affected by differences in soil moisture withmicrotopography. Spatial differences in this narrow area
must be monitored continuously, not only throughautomatic observation, but also through long-term on-site
observations.

c. Increase in ecosystem forest plots and tree census
and long-term maintenance over 100 years
With climatic changes, signs of changes in vegetation
have been reported. In North Slope, Alaska, by comparing
recent photos with photos from 1950, it was noted thatshrubs have increased in the tundra (Tape et al., 2006). In
addition, the dynamic global vegetation model has
predicted that deciduous forests that currently exist in
Eastern Siberia will disappear by 2300, with northward
expansion of the distribution area of evergreen forests intheir stead (Kawamiya et al., 2012). To capture changes invegetation over a 10-year, and furthermore, a 100-year
scale, it is expected that data measurement at vegetation
survey plots in various places continues over a 100-year
period at intervals of several years; relevant data includes,for example, species composition, number of trees,
diameter at breast height, and tree height. It will beessential to establish a strong human mechanism for
maintaining vegetation survey plots over this time scale.
In addition, it would be ideal for such plots to form part of
networks of long-term ecosystem research, such as thedomestic network JaLTER and the international network
iLTER, allowing for survey data to be a global asset. It
would also be very useful for such plots to play a role as
ground validation sites for satellite observations.
d. Long-term monitoring of vegetation ecosystems,
especially around ecotones
Due to large differences in the state of taiga and tundra
vegetation, there are differences in the albedo of theground surface, roughness, soil conditions, state of snow,
and snow accretion. There are also differences, in that theleading greenhouse gas is carbon dioxide in the taiga, but
methane in the tundra. For this reason, the respective heat,water, and carbon balances are different, and the
distribution of taiga and tundra greatly affect the climate.
To elucidate the state of vegetation, water cycle
information concerning stable isotope ratios (such as ofwater, carbon, and nitrogen) is very useful. Despite theimportance of the shift in the taiga-tundra ecotone, present
information is largely insufficient. For understanding
ecotone shifts, we need accurate monitoring in the field
58

PEN: Phenological Eyes Network

130Theme B: Earth system-modeling for inter-disciplinary research
Abstract

accurately. Of primary importance for both cases is thecorrect selection of parameters, and also the evaluation of
the effect caused by an error generated in one of the otherelements.
Each field, which forms the earth system model, has its
own subject. The central subject for the atmosphericmodels is verification of a non-hydrostatic, highresolution model which explicitly describes the behaviorsof clouds, and also a hydrostatic normal-resolution modelwith the cloud parameterization by using cloud data. The
subjects for the ocean models are improvement of watermass formation modified by the inflows to the Arctic
Ocean and vertical mixing, and also parameterization of
the ecosystem processes. The sea ice models have thesubject to improve dynamic and thermodynamic
processes at the pack ice scale and also mixed-layer
processes under sea ice cover. The subjects for the land
surface models include verification by use of
paleoenvironmental indices, application of data
assimilation techniques, improvement of duplication ofinteractions with the other elements, and then,development of the framework within the system model
for long-term integration or off-line experiments. Ourpreference would be to use the earth system model as abasis for linking various fields of the Arctic area, throughthe initiatives described for the individual fields.

If we try to understand the Arctic area, in which various
complex processes interact with each other, we need anearth system model to deal with the entire system. Here,the current state and challenges of modeling are discussed,from the aspect of individual fields, such as theatmosphere, ocean and land, and also system modeling ofintegrated fields. The key questions are as follows:
Q1: What are the development challenges for earthsystem modeling?
Q2: What are the development challenges foratmospheric modeling?
Q3: What are the development challenges for ocean-sea
ice modeling?
Q4: What are the development challenges for landcryosphere modeling?
For research using the earth system model, we can be
more efficient by selecting the one suitable for the timescale of the subject concerned. If the models are used to
predict outcomes for several years or less, they must be
precise and reliable. Hence, we need to achieve a higher
resolution in regional models. The models for studying thelonger time scales need to provide a secure representationof paleoenvironmental experiments and future projection.
For this purpose, it is desirable to develop models that
replicate the heat and water balances and represent thegeochemical cycles, ecosystems, snow and ice processes

Structure of this theme
challenges, and verification methods of earth systemmodeling from the perspective of Arctic research.
Numerical models are widely used as research devices
in the field of earth science, also beyond climate studies.
In this theme, we describe numerical models for the
primary purpose of understanding climate variability inthe earth surface layer. Elementary processes that are
objects of climate studies are distributed over atmospheric(physics, chemistry, and material cycles in the troposphereand stratosphere), ocean-sea ice (physics, chemistry,material cycles, and ecosystems) and land-cryosphere(ground ice, snow cover, soil, rivers, vegetation, andecosystems) components. Here, the material cycle usuallydenotes the biogeochemical cycle for the ocean and landbut is also used as more general terminology. First, we
describe the current state and challenges of earth systemmodeling, with these fields integrated in Q1, and thenfocus individually on atmospheric modeling (Q2), oceansea ice modeling (Q3), and land-cryosphere modeling (Q4).

The global climate system is a complex one, withinteractions between elementary processes occurring in
the atmosphere, ocean, and land surface. The Arctic ismuch more complex than other areas, because, in addition
to these processes that are present also in areas other thanthe polar region, the Arctic has cryosphere and ice sheet
processes also. To understand the various phenomena
occurring in the complex Arctic and also to accurately
project the future state of the Arctic (including
uncertainty), experimental equipment needs to be
developed and used, so that the sophisticated climate
system may be dealt with as is. However, it is actually very
difficult to prepare such a device in the real world. The
substitute is a computer numerical model, developed on
the basis of scientific principles and insights into natural
phenomena. The earth system model, which is expected toreproduce the climate-environment system, plays animportant role in climate and environmental research. In
this theme, we describe the present state, development

Q1: What are the development challenges for earth system modeling?
a. Introduction
We describe development challenges for earth systemmodeling through numerical models from the viewpointof Arctic research. In general, earth system modeling isused to denote a coupled model which includes the carbon
cycle and related elementary processes (IPCC/AR5); here
it is defined as a model to integrate multiple elementary
processes, taking the entire earth or a specific region into
account; if the latter, principles are extended to the entire
earth. Purely physical models are also dealt with. Pleaserefer to other sections of this theme or to other themes formodels dealing with only individual elementary processes.
Earth system models are developed on computers
having finite capacities or computational resources. It is
impossible to perform simulations for periods of several
thousands of years with models handling precise
processes or spatially fine phenomena. If we need to
explain climate variability spanning several thousands toseveral tens of thousands of years, we have to compromise,with coarse spatial expression or low resolution models. It
is therefore necessary to choose models appropriate forthe phenomena and targets being addressed. In Figure 60,131Figure 60: The time scales of the representative models (upper part) and the time scales of individual processes
related to the Arctic. If both time scales agree with each other between the models and processes, the models are
suitable for dealing with the processes.

using data assimilation methods (see Theme C). It isfurther desirable to advance collaboration withengineering techniques for social application of theseprediction results to marine state forecasts. The results ofhigh resolution models can be more easily compared withobservation data because topography and spatial
structures are precisely described, providing for spatial
correspondence with data. For this reason, such models
are useful as a basis for various research aspects related to
specialized field observations.
High
resolution
modelsrequiresignificant
computational resources for experiments and for analysesof results. We should consider wise use of computational
resources for problems that require high resolution in the
Arctic. In practical terms, effective methods are regionalmodels focusing on the Arctic area, using nesting
techniques to embed high resolution Arctic models withinglobal models having relatively lower resolutions. In the
United States, several research centers have collaborated
to develop and improve a regional model (RASM13) thatreflects elementary processes in the atmosphere, the ocean,sea ice, and terrestrial hydrology. However, no suchinitiative has yet taken place in Japan. Nesting of earthsystem models has just started, while atmospheric andocean models are independently nested withincorresponding global models. The research community inJapan should focus more on developing earth systemmodels using nesting techniques.
Below, we list individual issues related to highresolution earth system modeling. In connection with
Northern Sea Route predictions, we should promote thedevelopment of a sea ice model that precisely describes

we show the time scales of targets handled in typicalmodels and also time scales of the main elementary
processes involved in the Arctic area. Here, time scales
denote the time lengths for which targets and phenomena
may range. We describe the current state and future
development issues for each of the models suited todifferent time scales, and then outline issues with thesemodels, focusing on the evaluation of uncertainty.
b. Earth system model issues with time scales shorter
than several years
Models suited to this time scale are those with thehighest resolution; these are currently possible using
available computational resources. By increasing
resolution, it is possible for models to express flow fields
on steep topography, eddies, vortices, and convection.
Repeating the same type of experiments is effective for asensitivity study, as well as to separate random errors andstatistically robust results, allowing for more reliablepredictions. Examples of problems to be solved with thistype of model include predictions for the Arctic for
periods ranging from a season to a few years, as well as
quantitative estimates of anthropogenic impacts on
extreme weather events. A particularly relevant problem
in the Arctic is prediction of navigation through the Arctic
Sea Route, which is expected to become possible moreregularly as a result of the rapid decline in sea ice in recent
years. If we try to predict navigation over one year, weneed to improve atmospheric prediction by predicting
amplitudes and phases of natural variations. It is important
for this purpose to start predictions from initial conditions
consistent with model physics and observation data by132

but difficult to express due to insufficient resolution. For
heat and water balances, examples include clouds in theatmosphere and eddies and vertical mixing in the ocean.
For improved reproducibility, it would be indispensable toincorporate these effects with expressible forms in low
resolution models (parameterization). We need to promote
the development of parameterization in close cooperation
with elementary process models and b-models.
Another important point to be considered for c-models
is related to variations in material cycles and ecosystems
and their effects on climate variability. Earth systemmodels should express responses of vegetation andecosystems to climate variability. Forest fires andpermafrost melting are remarkable phenomena in the
Arctic. As a result, ground organic carbon decomposes,
emitting carbon dioxide and methane, which accelerate
global warming. It is necessary to express the feedback
mechanisms related to the carbon cycle to improveterrestrial ecosystem models, so that we may accurately
estimate carbon fluxes from photosynthesis andrespiration, and also carbon stocks from plant biomass andsoil organic carbon under conditions of climate variability.
Vegetation variability is also important because of theeffect on albedo. Modeling of material cycles andecosystems is insufficient in Japan relative to someforeign countries; this is not ideal for Arctic research. We
expect further development of these element processmodels, which can be directly linked to earth systemmodels.

mechanical processes in the ice edge zone. We need tointegrate material cycle and ecosystem models with highresolution physical models, so that we may understandboth localized phenomena and effects on large-scale
climate fields. However, in order to efficiently use limited
computational resources, we need to develop model
structures within which elementary processes can beeasily added or removed, in accordance with thesimulation aim.
c. Earth system model issues with time scales ofbetween ten and hundred years
The models used for problems with this time scale(referred to as c-models) provide options for studying
recent and future climate variability in the Arctic areafrom various perspectives. “c-models” usually have lower
resolution than models for problems with time scales
shorter than several years (referred to as b-models), andoften deal equally with the entire earth, not limited to the
Arctic area. As experimental devices, c-models can beused with less computational resources than b-models andare hence used more easily for discussing interactions
between many systems, including material cycles andecosystems. Global c-models can be used to discussinteractions between the Arctic and other areas, forexample, with respect to the effects of variations in sea ice
and land surface on weather statistics in Japan.
Let us look at the future predictions of the IPCC
assessment reports as a specific example. Japan
contributed significantly to the IPCC assessment reports
through “the Human-Nature-Earth Symbiosis Project”,
which commenced in 2002 for AR4, and through the“Innovative Program of Climate Change Projection for the
21st Century”, which commenced in 2007 for AR5. “cmodels” played a significant role in these IPCC reports. A
global model that includes the Arctic area is currently also
being developed through the “Program for Risk
Information on Climate Change”, which commenced in2012. However, in terms of models dealing with the Arctic,
where climate is changing more rapidly and extensively
than in other areas, it is not sufficient to reproduce thepresent state. We should continue model development aspresented below, so that various states that could occur
may be reproduced with statistical stability. The
evaluation of model reproduction is discussed in Section e.
Heat and water budgets are important elements forrepresenting climate variability in earth system models.
Cryosphere processes in the ocean and on the land surface,such as sea ice, land ice, permafrost, and snow cover, areparticularly important in the Arctic. These processes
significantly affect heat and water balances throughalbedo variations, possibly inducing climate variations at
the decadal time scale. The reliability of climate
variability projections could be improved byincorporating components that are not yet sufficiently
represented in earth system models, e.g., reductions in thealbedo of snow and ice due to dust and micro-organisms,
and the thermodynamic effects of melt ponds on the uppersurface of sea ice. In addition, it is important for earthsystem models to ensure consistency across these element
models, which are often developed individually. We needto deepen understanding through collaboration between
researchers working in various fields, such as the ocean,land surface, etc.
In the case of c-models with relatively low resolution,
there are many elementary processes that are importantd. Earth system model issues with time scales beyond
hundred years
When problems with this time scale are dealt with, we
use earth system models (referred to as d-models) withsimilar structures but that can be operated with fewer
computational resources than c-models. The concrete
strategy is to lower resolution and to express elementary
processes more simply, including through moreparameterization, allowing us to carry out experiments
spanning longer periods of time. Examples of problems
include simulation of paleoclimates and experiments forunderstanding ice sheets and the deep ocean over longtime scales. “d-models” can be operated for individual
experiments with smaller computer resources and cantherefore be useful for a large number of experiments;
examples are sensitivity studies to examine results byvarying model settings from one case to another. To beused for these various purposes, d-models are thus
expected to contain a number of elementary processes andparameterization, which can be easily added or removed
in accordance with the simulation aim.
The other purpose of d-models is to develop “All-in
models” by adding ice sheets, vegetation dynamics, andcrust isostasy to those composed of physical, material
cycle, and ecosystem components. Models with more
processes lend significance to Arctic research, since there
are more processes here than in other areas. Most newlyimplemented processes have a wider variety of time scales
and spatial sizes than processes that are already included.
Examples of additional components are ice sheets, which
are located at limited locations but that have time scales
longer than one thousand years, and also vegetation
dynamics, which act on interactions of vegetation types
and sizes with climate variations over time scales ofseveral decades to several centuries. The combination ofthese new elementary process models is a major scientific133characteristics, it is of course necessary to improve lowperformance components by understanding individual
processes and developing more reliable models.
Simultaneously, it is extremely important to evaluate error
amplitudes relative to others by verification of earthsystem models as a whole.
With regard to methods of evaluation and verificationof model uncertainty, we may refer to existing intercomparison projects of numerical models. Examples
include CMIP5, one of the groups promoting prediction
research in IPCC-AR5, and AOMIP, the Arctic Ocean
Model Inter-comparison Project. It is important for the
research community in Japan to actively participate inthese projects, so that researchers understand theuncertainty of their own models by transmitting theirinformation and making comparisons with other earthsystem models. Three additional proposals are given
below.
The first point is the necessity of monitoring andstandard metrics for evaluation specific to the Arctic area.
For earth system models covering the Arctic area or theentire earth, observation information covering a wide area
is very important. Observation data are not sufficientwhen compared with other areas, due to the difficulty ofobservation. For this reason, monitoring is expected to beenhanced in future (refer to Theme A). In addition,
standard metrics for evaluation should also be establishedto evaluate the uncertainty of certain processes in themodels. One example is ocean current intensity along theshelf edge in the Arctic Ocean, as defined in AOMIP.
Another example is sea ice cover: i.e., although the icecovered area has been widely used, net metrics would be
required to comprehensively evaluate the analysis outputsof dynamic fields.
The second proposal is for mutual enlightenment ofmodeling and monitoring from the viewpoint of systemmodeling. It is difficult for monitoring to directly measurespecific elementary processes. It is also difficult to
directly observe parameters that specify the intensity ofprocesses expressed by parameterization in the models.
We hence propose comparison in the following way. Fromthe modeling side, we examine the effects of parameters
on variables, such as temperature, salinity, and velocity,using sensitivity studies and data assimilation (see Theme
C). From the monitoring side, observation accuracies arepresented for these variables. If model errors are larger
than observation errors, we assume that models are notsufficiently comprehensive, or that they have large
uncertainties. This method is useful for verification ofearth system models, and also indicates observation
parameters and monitoring methods as significant
outcomes.
The third proposal is for a method to evaluate theresponses of the earth system model to main factors ofclimate variability. For example, if we consider air
temperature, we compare the contributions of individual
processes, taking the energy balance as a medium (see Q5
in Theme 1). Using this type of method, we can evaluate
the relative importance of individual processes in earthsystem models. We can also compare evaluations acrossdifferent models, and investigate dependence on various
parameterization methods so that we may reduce
uncertainty ranges. Once this method is combined withdata assimilation, the responses of the actual earth may beevaluated.
In Q1 here, we have described issues related to thechallenge by itself. We should actively contribute toprojects to implement new elementary process models inearth system models.
The earth system model, once built as described above,
could express large-scale transitions specific to terrestrial
ecosystems, such as advances of the taiga forest into thetundra region due to global warming, and regime shifts ofthe vast amounts of organic carbon accumulated in Arctic
peat lands (Ise et al., 2008). Here, we focus on interactions
between the ecosystem and climate variability through thematerial cycle. Since such interactions often occur with along time lag from impact, we need to develop the modelthat reproduces long time scale processes.
It is difficult to verify experimental results of d-models
against observation data, because observation data havenot been continuously obtained for more than 100 years.
The results of paleoenvironmental experiments are
therefore often verified in comparison with proxy indices,which are considered to reflect certain aspects of the pastenvironment recorded in core samples taken from seabedsediments and ice sheets, or temperature and precipitation
recovered from the proxy indices. Attempts to reproduce
the paleoenvironment in earth system models areimportant for improving model reproducibility.
Furthermore, if proxy values can be produced in themodels and compared with data, the reliability of earthsystem models, including the Arctic area, would be
improved. It will be indispensable to improve various
model aspects, such as sea ice distribution, changes invegetation distribution, the production processes of dust
and micro-organisms, transport of various aerosols in theatmosphere, isotope ratio changes in the atmosphere,
isotope ratios and acidity of seawater, and ocean
circulation in and around the Arctic Ocean, including deep
water formation. It would be ideal for researchers invarious fields to collaborate with each other, including
with researchers specialized in observations.
e. Issues relating to earth system models: evaluation of
uncertainty and collaboration with monitoring
The current states and development issues of earthsystem models have been described in previous sections
by separating these into several time scales. The otherimportant issue relates to verification and evaluation of
uncertainty included in model results by comparing model
results with observation data, with uncertainty often
related to model errors and also to shortage of scientificunderstanding. Here, we outline issues and related
proposals concerning verification of uncertainty in Arctic
earth system models.
During discussions, we need to take note of theimportance of uncertainty in earth system models, i.e., wecannot understand uncertainty by simply superimposing
uncertainties of the individual elementary process modelsof which the earth system models are composed. In mostcases, individual elementary process models are verified
with experiments under the “right” boundary conditions.
However, the elementary process models built into earthsystem models are driven by information comprisingerrors from the models, thus conveying additional errors
to other models. These errors are sometimes amplified due
to interactions between elementary process models, while
in some cases, errors do not significantly affect othercomponents. Research on elementary processes cannot
solely explain what interactions will occur. To reduce
uncertainties in earth system models with such
134

system models, with a focus on the Arctic, we will
improve reproducibility and reliability of the models, notonly for the Arctic but also for the entire earth. Further, we
can contribute to connections between various academic
fields and also with society. Fortunately, Japan has
researchers working on both modeling and observation in
many fields. It is therefore desirable for researchersfamiliar with various methods in various fields tocontinuously and cooperatively pursue development andverification of earth system models.

uncertainty of earth system models, along with proposals
to address the challenges involved. The issues andproposals are common to all areas, even if they areparticularly important for the Arctic. The reason for thelatter is that so many processes interact in sophisticatedways and that Arctic models have larger error than models
for other areas. Furthermore, there can be significant
demand for information given recent rapid changes in the
Arctic. From the reversal point of view, by posing
challenges to develop and reduce uncertainty of earth

Q2: What are the development challenges for atmospheric modeling?
and wind data.

a. The present status of research and related issues
First, we review the history of atmospheric model
development with respect to problems specific to the
Arctic. During the early stages of model development,
gridding and process parameterization were common to
the entire earth, rather than paying specific attention to thepolar region. Representative parameterization is cloudformation, which has a very small horizontal scale. A
numerical model usually has variables specified at grid
points that are uniformly distributed along each coordinate
axis. However, atmospheric models have been formalized
to a spectral model, in which variables are expanded into
horizontal Fourier modes, so that numerical errors may beremoved in model calculations. The grid model on theconventional latitude-longitude system suffers from the
problem of a very small time step with high longitudinal
resolution (referred to as the polar problem). On the other
hand, the spectral model has a problem of significant
computation time for communication between many
modes. To solve these problems, the numerical model
based on icosahedrons, NICAM, has been proposed,
together with non-hydrostatic dynamics and highresolution (Satoh et al., 2008).
A widely used method for focusing on a certain regionis to connect a regional model with a larger-scale modelthrough boundary conditions for both, referred to as“nesting”. This method has been used for detailed weather
forecasts of a certain region, and has also been applied to
Arctic regional models, which are connected with global
models along boundaries in certain latitudes. Suchprojects have been promoted by international
collaborations, such as MM5, and its successor, WRF. The
models developed in Japan, JMA-NHM and CReSS,
could also be applied to polar regional models. A regionalmodel facilitates parameterization specific to a certain
region. Some projects using Arctic regional models are
currently underway, in which storm tracks are being
predicted and verified in comparison with the actual
phenomenon through a focus on increased low-pressure
disturbances in recent years.
The Arctic area is usually covered by more clouds insummer and by fewer in winter. In spring and autumn,
cloud amounts increase (decrease) responding to larger(smaller) open water areas, significantly affecting energybalances through the sea surface (see Theme 2). A studyof note was carried out, verifying cloud distributions in a
global atmospheric model; and reanalysis fields were also
produced by assimilating observation data within the samemodel (deBore et al., 2014). Even though the study was
based on substantial summer data, it is more difficult toreproduce cloud distribution and sea surface energybalances, compared with highly reproducible temperatureb. Future research
We should improve the reproducibility of climate in thepolar region by effective use of various hierarchicalmodels, from global to regional, and from conventionalcoarse grid models to high resolution LES (large eddy
simulation) models. To achieve this, model improvement
is necessary based on verification against observation data
for appropriate expression of polar clouds in numericalmodels. The processes involved are aerosol-cloud
microphysical processes, boundary layer mixing, andradiation processes; and these could be expressed in themodel, once it is verified against accurate observation data,
and also equipped with improved numerical schemes(techniques used for numerical calculations).
The fundamental solution for exploring physicalprocesses is to express phenomena explicitly with highaccuracy, rather than through parameterization. Using thehigh resolution LES model, we should attempt to
explicitly resolve turbulent flow in the land surface
boundary layer, and also to precisely reproduce clouds,
including cloud microphysical processes, by use of the bin
method, in which cloud particle sizes evolve, shiftingfrom one bin to the next. In particular, it is a challenge toreproduce cloud physics, including ice crystals andmultiphase states. To correctly express the height of theboundary layer, cloud bottom height, and cloud thickness,
we have to improve the boundary layer and cloud
microphysics processes, and also consider reproducibilityof large-scale fields. To understand the relationshipbetween large-scale synoptic fields at high and low
pressure scales and clouds and weather in the polar region,
we expect usefulness not only of conventional global
models with hydrostatic dynamics but also of regionalmodels (WRF, JMA-NIM, etc.) and global nonhydrostatic models (NICAM, etc.). NICAM has features
to explicitly express cloud physical processes and has
been applied to research relatively small scale phenomena,such as typhoons, for which we expect to reproduce cloudformation through non-hydrostatic processes. In terms ofapplications to the Arctic, we have started analyzing
Arctic low pressures and verifying storm tracks, while
verification of cloud formation may also be significant.
By reference to objective verification, in which theresults of several global models are compared withreanalysis fields, we propose a study to compare acommon variable between observation data and the resultsof several different types of models. This comparison
project should be performed with a focus on cloud
distribution, which is important but difficult to reproduce.
Model members include the global non-hydrostatic model,
135and also regional models nested within global models.
With respect to dynamics in comparison with nonhydrostatic models, members need to include hydrostatic

models with cloud formation parameterization. In the caseof several models being used, several researchers or
institutes would need to form a collaborative team.

Q3: What are the development challenges for ocean-sea ice modeling?
with parameterizations for mixing processes, in which
temperature and salinity fluxes are included in terms asfunctions of the isopycnic layer thicknesses for eddyinduced mixing. Mixed-layer development is controlled
by turbulent mixing.
CCSM4 has reproduced representative water structuresin the Arctic Ocean, even if there are a few problems to beresolved, including the location and strength of theBeaufort Gyre, the depth of the temperature maximum in
the Atlantic Water layer, volume and heat transport
through the Fram Strait, and temperature in the deep
Arctic Ocean. These problems are partly related to the low
horizontal resolution and poor reproducibility of deep
water supply caused by vertical mixing. For horizontal
resolution, it is therefore necessary to partly increase theresolution in the main straits and bottom topography, orinstead to adjust topography so that fluxes may be fittedwith observations. As for vertical mixing, we need toreconsider whether the parameterizations of breaking
internal waves and deep dense water flow are appropriate
for the Arctic Ocean.
Although uncertainty still remains, due to a lack ofobservation data and quantitative discussion, we need tonote the following important processes. For variability of
the heat flux, which starts in the Atlantic Water layer,
crosses the halocline, and reaches the sea ice cover,a. The present status of research and related ocean
model issues
The Atlantic Water flows into the Arctic Ocean throughthe Fram Strait and the Barents Sea, forming the Fram
Strait branch water and the Barents Sea branch water. The
Barents Sea branch water increases its density due to sea
surface cooling in the Barents Sea and penetrates
underneath the Fram Strait branch water (Figure 61).
These water masses flow as a cyclonic boundary current
along the Siberian shelf slope and affect stratification in
the basins due to shelf-basin interactions. On the other
hand, the Pacific Water, which flows through the Bering
Strait, interacts with Siberian shelf water, the Atlantic
Water, and saline water rejected from sea ice formation,
contributing to sophisticated stratification in the Canada
Basin. The stratification produced from the surface mixed
layer, eddy motion, and water mass transport from theshelf edge to the basin area are crucial processes for ocean
models to reproduce ocean circulation in the upper layer
and the basins.
With regard to modeling status, we first describe thecurrent state of reproducibility of the Arctic Ocean using
earth system models, by referring to CCSM4 used for a
climate study as a typical example (Jahn et al., 2012). The
ocean model, POP2, implemented in CCSM4, hashorizontal resolution of 1 deg and 60 vertical levels, along

Figure 61: Schematic of near-surface circulation of the Arctic Ocean (solid arrows known flows; dashed arrows,
presumed flows). Vertical section from Bering Strait to Fram Strait indicated by a black dotted line connecting isshown in Figure 62. Bathymetry is from IBCAO.

136

background physical fields. In Japan, although the target
area was not the Arctic, comparison of model results was
performed by coupling a common ecosystem model withvarious physical models. We need to establish an effective
evaluation method.
As sea ice cover declines in the Arctic Ocean,biological productivity may become more active in thebasin area, and it will then be necessary to express
appropriately iron-limitation processes and transport
processes of shelf waters rich in iron. At the stage of
discussing differences between ocean areas, we mightneed to incorporate denitrification and nitrogen fixation
processes. These issues are central, even for ocean-onlymodels; and we should hence consider, on the basis of
obtained knowledge, the extent to which these should be
dealt with in earth system models. The verification ofmarine ecosystem variables is usually carried out bycomparing chlorophyll concentrations estimated fromsatellite measurements and nutrient concentrations basedon in situ measurements. However, significant errors
associated with subsurface chlorophyll maxima are
included in the satellite data algorithm, by which a
vertically integrated amount of primary production isestimated from information collected at the sea surface.
As for nutrients, it is only the World Ocean Atlas thatcovers a large area. This data set retains only climatic
information and hence is not usable for discussion of interannual variability. The problem is thus that observation
data for the marine ecosystem are too limited comparedwith physical data.

important processes include vertical mixing caused bywinds and tides, upwelling Atlantic Water along the basinrim, and vertical circulation due to eddies (Figure 62).
Further observation data and process studies areindispensable for understanding the spatio-temporalvariability in these processes (refer to Theme 2 fordetailed process studies). The steady state in the middle
and deep layers of the Arctic Ocean is maintained by deep
water, which is supplied by an overflow from theGreenland Sea, rises slowly and mixes with even a small
amount of water penetrating from the middle layer. In
cases when there is no realistic supply of deep water, an
extremely small vertical mixing coefficient could help
vertical stratification, whereas the steady state is different
from the real field. Both intrusion of deep water andmixing with the middle layer are therefore necessary forhaving a realistic vertical profile in middle and lower
layers. These deep water formation and transport
processes are particularly crucial for long-term integrationof the century scale (refer to Q2 in Theme 5 for middle
and deep layer circulation).
When incorporating marine ecosystem processes into
earth system models, we should consider the number ofnutrients and biological species. As long as the governing
equations are not extremely complicated, the related
computational load is not high. However, advection anddiffusion calculations increase in proportion to the numberof variables, with the computational load then becoming
higher for schemes with high accuracy. We should
therefore select only nutrients and plankton species thatare definitely necessary. Another option is compromise,by using a scheme with lower accuracy for biological andchemical variables. It is not easy to determine what is
responsible for a mismatch with observation data, whether
uncertainty of ecosystem processes, or reproducibility ofb. The present status of the sea ice model and related issues
We need to focus on sea ice variability at time scales
from several days to several decades, with considerationof variability in the earth system at time scales shorter thanFigure 62: Schematic of vertical structures and sea ice-ocean processes in the Arctic Ocean(see Figure 18 of Theme 5).

137

results have suggested the need for parameterization of
fast ice formation and growth, so that the
reproducibility of sea ice cover may be improved along
coastlines with fast ice. In addition, the seaward
extension of fast ice provides crucial information forthe safety of vessel navigation along the Northern Sea
Route and hence should be noted as a future issue forroute prediction.
The three problems described above have been noted to
be important, even if quantitative discussion based on
observation data is not yet sufficient, requiring further
refinement. First of all, we need to understand physicalprocesses and quantitative estimates using observation
data and process models. Using the technologies and dataof satellite observations, where Japan’s achievements arehighly valued, we expect to develop new schemes andparameterization to be used in earth system models. The
concentration and area of sea ice are widely used forverification of sea ice models, although ice thickness dataremain insufficient (e.g., Jahn et al., 2012). Given the factthat sea ice is changing from multi-year to seasonal in the
Arctic Ocean, we should enrich ice thickness data throughcontinuous observations in time and space, as animportant element of this long-term plan. The scaledependence of ice deformation rates is expected to be
useful for examining the reproducibility of the sea ice field,
through comparisons between observations and models.

several years, and also from a decade to a century. At
present, coupled sea ice-ocean models with atmosphericforcing reproduce well seasonal and inter-annual
variations larger than several tens of kilometers in the sea
ice area: e.g., AOMIP. However, coupled atmosphere-sea
ice-ocean models (such as CCSM4) underestimate therapid decline trend of sea ice cover. Even though thisdiscrepancy is not attributable only to sea ice models, we
discuss the dynamic and thermodynamic processes of sea
ice, to be considered for future earth system models. Sincesome points have already been discussed in Theme 2, we
focus here on three problems.
(1) Two fundamental processes for dynamic growth ofice thickness are ridging and rafting in ice covercomposed of ice floes. Ridging means a thickness
increase by deformation due to collision of ice floes,
and rafting describes one ice floe running above
another. Both processes are crucial to changes in thespatial distribution of sea ice thickness. Since there are
inadequate observations to understand the extent towhich sea ice experiences ridging and rafting, it is still
difficult to express ridging and rafting of relatively
thin ice in gaps between thick ice floes, even if thismay be an important deformation process for ice floes
smaller than 10 km.
(2) In mixed layer processes underneath sea ice, brine(high salinity water) rejected due to sea ice formation
tends to mix with surrounding sea water andcontributes to deepening of the surface mixed layer,
resulting in a heat flux from the subsurface layer to thesea surface. In addition, heat release also occurs due
to turbulent mixing driven by winds and breaking
internal waves. It is thus crucial, in terms of thethermodynamic processes of sea ice, to understand theextent to which the mixed layer depth changes below
sea ice and how much heat is transported to the sea
surface or to the bottom surface of sea ice.
(3) With respect to the effects of fast ice, AOMIP modelc. Contribution and roles of the research community
in Japan and relationship with main projects
Two climate models are well recognized in Japan as abasis for earth system models; MIROC was developed by
UT-AORI, NIES, and JAMSTEC for MIROCESM, and
MRI-CGCM was developed by JMA-MRI for MPI-ESM1.
These two climate models participated in CMIP organized
by WCRP, and contributed to the future projections ofglobal warming included in IPCC-AR5. From now on, we
should develop earth system models based on the latest

Figure 63: Schematic figure of approaches by AOMIP/FAMOS, taken from Proshutinsky et al. (2011).

138

see Theme 2); our roles will be increasingly important also
for FAMOS, the successor of AOMIP. Sea Ice Outlook is
an international project forming part of SEARCH, aiming
to provide predictions of the summer sea ice areas in early
spring; Japan supplies these predictions, using satellite
data. Since observation data are indispensable for
improvement of earth system models and climate models,
our contribution to this type of project will be morevaluable through use of satellite data, Japan’s specialty.

climate models (e.g., MIROC5, Watanabe et al., 2010),
and contribute to research for CMIP6 and IPCC-AR6, in
which we will attempt to understand the processes listed
as issues for ocean and sea ice modeling (see also Theme
2) and to reduce uncertainty in projections by implementing
ocean and sea ice models in earth system models.
Research using the sea ice-ocean component of MIROC
has contributed to AOMIP specifically through coupled
sea ice-ocean models of the Arctic Ocean (Figure 63, and

Q4: What are the development challenges for land-cryosphere modeling?
detailed process models are required to understandvariation mechanisms and to make predictions. The
problems of ice sheet modeling have a wide temporal
range, from a century to 100 thousand years. When we
consider shorter time scale problems, such as variability
in the Greenland ice sheet’s response to global warming
over 100 years or so, reproducing the present state isimportant. For this, we need to express the basal sliding
process, using data assimilation techniques for ice sheet
models. For model verification of these processes having
time scales too long for monitoring, as in the case of land
surface models, we need to attempt verification throughcomparisons with paleoclimatic information. Althoughconventional ice sheet models cannot express localized
fast motion, which is dynamically important, we should
improve models to reproduce ice sheet variability at longtime scales, on the basis of understanding localized
motion variations and their impacts on large scale motion.
From the perspective of long-term research anddevelopment, earth system models may have to be run
asynchronously, with ice-sheet models integrated
continuously for long periods and climate models
integrated intermittently for short periods. Technologicalinventions are critical for managing very large
computational resources. To understand ice sheet
variability, in the past, present, and future on a common
basis, asynchronous coupled ice sheet-climate models areindispensable, requiring careful selection of processes.
The additional requirement is to appropriately introduce
interactions between the atmosphere, the ocean, and thesolid earth. As for coupling with the atmosphere, both ice
sheets and glaciers require high horizontal resolutions to
calculate melting. Typical coupled models now fill
resolution gaps by introducing empirical mass balance
models between the two models, although we also expect
improvement of coupled models using physical models to
explicitly include ice sheet topography and other small
scale features. As for coupling with the ocean, ice sheets
may receive impacts from basal melting of ice shelves andseparation of icebergs (calving). Modeling of theseprocesses is still immature, with large uncertainties, andrequires high-priority development.
Researchers in Japan have participated in intercomparison projects of ice sheet models and climate
models related to ice sheet variability (Bindschadler,
2013; Sueyoshi, 2013, etc.). In particular, it is noteworthy
that ice sheet and paleoclimate modeling researchers inJapan played a central role in determining boundary
conditions during the last glacier maximum experimentsof PMIP3. An important challenge for us is to stay at theforefront of model development, with a clear presence in
the ice sheet-climate modeling community.

In some cases, it is possible to reduce uncertainty ofphenomena for the land surface element in earth systemmodels at decadal to century time scales, by improving thephenomena at time scales from 1000 years to 10000 years.
This element model could thus be verified and thenimproved by using dust aerosols and atmospheric methane
concentrations, which have been reconstructed from
paleoclimatic indices and shown to be different indifferent eras. Dust aerosols are dependent on vegetation
cover, soil moisture, and wind speeds, and methane
emissions are dependent on wetland distribution andorganic carbon stocks. These parameters can therefore beused for verification of land surface models, even if
present-day data samples are too limited and cannot be
used for quantitative comparison with models. As a result,
we expect a reduction in the uncertainty of global
warming predictions focusing on the century scale. In
addition, dust accumulation is influenced by atmosphericcirculation transport and dust data could thus contribute toverification of global atmospheric circulation. Since dust
and methane affect climate through radiative forcing,
reducing their uncertainty is important for future
predictions.
It is important in the land-surface and cryospheremodels to accurately reproduce variability in permafrost
on a decadal scale and longer. In contrast to snow cover,which usually melts away in a year, permafrost isdependent on small heat fluxes, then acting as a memory
and influencing heat fluxes, soil moisture, and vegetation
for a long time. In addition to improving elementary
process models such as water permeability to thepermafrost, an important issue is how to reasonably
determine the hydraulic and thermal parameters of soil at
the global scale. Since vegetation cover on the land
surface and the thickness of the withered material layer
also significantly affect permafrost behavior (Yi et al.,2007), vegetation variability is crucial for permafrost
variability predictions. Please refer to Q4 in Theme 12 forissues relating to individual elements, such as thepermafrost, the atmosphere, snow cover, and vegetation.
Here, we focus on model development of ice sheets andglaciers, the processes for which have been described in
Theme 4. Ice sheet processes are unique in the sense that
topography is usually fixed in atmospheric and ocean
models but changes in the ice sheet models. Ice sheet andglacier models are ultimately common, although theyoften have different configurations, depending on
application to typical problems and for different purposes.
Individual glaciers are small, but so many of them have asignificant impact on sea level over a shorter time scale.
Simplification and parameterization need to be developed
so that several glaciers can be treated in the expression of
integrated impacts. At the level of individual glaciers,
139

Theme C: Data assimilation to connect monitoring and modeling
Abstract

numerical modeling techniques. For practical reasons,data assimilation research for the Arctic has to be selectedaccording to the handicaps of the area: i.e., atmosphericmeasurements have limited coverage, sea ice thickness is
not measured in situ, and remote sensing data are notavailable for the sea water. The long-term future direction
is likely to be challenging for data assimilation to themulti-disciplinary system and aiming at the operational
objective to implement forecast of the Arctic Ocean state
for the safe sea routes. Considering the limited resources
for Arctic research in Japan, an appropriate path ispresented here, with regard to data assimilation research
proposal. This report has touched on the necessary
terminology for data assimilation literature andinformation on the discussed technology.

Here, we describe the techniques of data assimilationand the application to the Arctic environmental research,
along with a survey of the present status. It has been
confirmed that advanced techniques are in place for theoperational forecast and the reanalysis system to be
applied to the atmosphere-sea ice-ocean system. In thefields where data assimilation techniques have not been
applied extensively, such as state estimation of the ice
sheet, some applied examples are introduced. The current
situation, as described above, has been built on theknowledge that long-term monitoring is important, thereinforcement by the improvement of observation
techniques and the recognition of rapid climate change.
On this basis, the future direction is proposed to combine
observational techniques, and networks as well as

Introduction
rest of the world, and we hence need to consider work inthis field with a top priority.
Here, we propose applying data assimilation techniques
to explore individual processes related to environmental
variability in the Arctic region. The international Arctic
research community has projects to carry out observationsin the Arctic Ocean (e.g., WWRP-PPP*, * is explainedlater), aiming at improvement of numerical models andforecast capability along with state estimates through data
assimilation techniques. Following this trend, this longterm plan also proposes a research direction to bridge
observational and modeling communities. In addition, wesurvey the current status of this work and propose
applying data assimilation techniques to research fields towhich these have not yet been applied, such as to ice
sheets and the carbon cycle.
This theme has the following structure, with manytechnical terms. The representative techniques, variational
method*, and Kalman filter method* are explained in Box
10. Table 3 lists data assimilation techniques, along withproject names. The terms explained in Box 10 and Table
3 are identified with *. In the first part of the text,
examples of data assimilation used for Arctic
environmental issues are analyzed, followed by proposed
future research directions. The second part presents
practical proposals for data assimilation research. In thelast part, we list problems for the Japanese researchcommunity of the Arctic environment to address, by
carrying out the data assimilation research, andcountermeasures are also proposed.

Data assimilation is a general term for a technique to
produce useful information by combining a model
solution with data collected from a common system. Dataassimilation has two objectives: state estimate and timeseries control. The state estimation technique combines
observed data with model variables and estimates areasonable state of a system that contains large uncertainty
due to no direct observations or highly uncertain data. The
time series control technique guides progression in model
variables through sequential matching with data. These
two kinds of techniques are usually used in optimal
combination for individual data assimilation systems: forexample, in the weather forecast system, the state estimate
technique provides an initial condition of an atmosphericcirculation model, with the time series control techniquethen putting forecast error growth under control.
In global environmental research, data assimilation is a
powerful tool for understanding various phenomena
occurring in the climate system composed of theatmosphere, sea ice, and ocean, by combining
observations, data analysis, modeling, and theoreticalstudies. Data assimilation is a basic technology for
integration of these research methods, with potential for
its outcomes to feed back into methods, throughoptimization of observation networks, production ofreanalysis data, and estimation of model parameters. Oncea physical model is coupled with chemical and biologicalcomponents, the data assimilation technique is capable ofintegrating different research fields. Data assimilation
studies in Japan for the Arctic lag significantly behind the

The present state of data assimilation research in the Arctic area
Data assimilation techniques have been implemented to
produce estimates and forecasts of the troposphere and sea
ice cover in the Arctic, for which data are collected
regularly with satellites and instruments deployed on sea
ice. These techniques are not extensively applied to theocean interior because of the difficulties of continuous
monitoring due to sea ice cover. However, observations oftemperature and salinity under sea ice cover have come tobe more representative of reality, following development
and improvement of under-ice instruments such as ITP*
(see Theme A for details). Hence, data assimilation for the

ice-ocean component is progressing, along with
development of observation networks. A main focus of
this section is the review of research and operational
activities for the atmosphere, sea ice, and ocean in the
Arctic area. We then also provide an additional report onstate estimates of atmospheric chemical compositions andof the Greenland ice sheet, for which satellite observation
systems have been greatly improved.

140

mismatches in temperature and humidity than winddirection and speed. Our urgent task is to identify thecause of these mismatches and to improve physicalprocesses.
One of the reasons for these mismatches in Arctic
reanalysis data is thought to be the fact that many
parameterization schemes have been determined on thebasis of mid- and low-latitude data. One solution toaddress this problem is to construct reanalysis data usinga regional model suitable for the Arctic region. The
pioneering work in this respect was carried out by aresearch group at the University of Ohio, producing Arctic
atmosphere reanalysis data, ASR*, from Polar-WRF*
optimized for the Arctic atmosphere, where the data
assimilation technique used was the three-dimensional

a. Reanalysis of atmospheric data
In various countries, operational divisions produce
atmospheric reanalysis data using data assimilation
techniques from observed data and numerical modeling.
However, it is widely known that reanalysis data containsome problems. For example, all global reanalysis data
sets show significant deviations from fields observed withradiosondes in the Arctic atmosphere (Jakobson et al.,2012). In particular, significant mismatches were found in
the inversion layer of air temperature and moistureprofiles near the land/ice surface, suggesting problems inthe boundary layer scheme on the land surface or theboundary condition at the sea ice surface. As presented byother studies, the boundary layer at the sea ice surface ofthe representative reanalysis fields commonly has larger

Box 10 Explanation of data assimilation techniques
There are now two main groups of data assimilation techniques used in the fields of atmosphericscience and oceanography: i.e., the variational method and the Kalman filter method, which arebriefly explained here. The detailed techniques and applications, including other technicalinformation, are described in the textbook edited by the Japanese data assimilation researchcommunity (Awaji et al., 2009).
a. Variational method (Adjoint method): 4DVar/3DVar
By correcting the variables that determine model behaviors (control variables), the functions tomeasure distances between observation data and model outputs (cost functions) are minimized.
The model variables that are determined from optimized control variables are defined as theanalysis values. The control variables are usually selected from initial conditions, boundary
conditions, and model parameters. The analysis values strictly satisfy the governing equations of
the model (Figure 64a). The method is called the four-dimensional variational method (4DVar) incases where time is included in the governing law, while it is called the three-dimensionalvariational method (3DVar) in cases where time is not included.
b. Kalman Filter method
The Kalman Filter method has the characteristic that the model governing equations retain thetemporal evolution and explicitly produce the error covariance matrix of forecast values from initialand boundary values, including errors. The optimal solution (analysis values) is obtained by linearlyadding forecast values and observation data. The optimal solution therefore does not satisfy thegoverning equations at the times of analysis or assimilation, although it is easier than in the caseof the 4DVar to obtain analysis time sequences that follow the observation data (Figure 64b).141

Figure 64: 4 ‐ dimensional variational(4DVar) method and Kalman filter
method. Red circles denote observed
data, black circles and lines denoteanalysis values, and blue circles
denote model prediction values. Statevariables can be temperature, velocity
and others.

141sea ice concentrations in the Sea of Okhotsk using thenudging method* (Usui et al., 2010). In addition,
reanalysis fields of sea ice concentration have been
estimated using the three-dimensional variational method
and assimilated with global atmosphere-sea ice-ocean
models using IAU* (Toyoda et al., 2011). We areinterested in this trend of assimilation of sea ice data to
improve forecast accuracy of the atmosphere (and theocean in the case of Environment Canada).
Let us look at operational data assimilation, with afocus on analysis of sea ice fields. As a typical example,
Environment Canada has developed RIPS*, the system forregional sea ice analysis and forecast. This system is built
on a model of sea ice movement, with the aim of
automatically estimating sea ice states, the latter preparedmanually by forecast operators. Sea ice concentration
fields are produced four times a day, matching withweather forecasts, and provide information for sea ice
charts and bottom boundary conditions in numerical
weather forecasts. With regard to ocean circulation data
assimilation, there has been very limited application todate due to the lack of observation data for the oceaninterior. Research results by the University of Alaska havereported that the four-dimensional variational method*
was applied to estimation of climatic ocean circulation in
the Bering-Chukchi sea area.

variational method. Another attempt involved preparationof reanalysis data, CBHAR*, specified for the atmosphere
over the Beaufort Sea and the Chukchi Sea, using theregional data assimilation system WRFDA* on the basisof Polar WRF.
In the field of the atmospheric sciences, it is possible
for an individual research group to construct a regional
reanalysis product from global observation data sets;hence, data assimilation experiments are now carried out
to examine the influences of additional data on reanalysis
results over the Arctic Ocean. The results of the data
assimilation system, ALERA2* developed by JAMSTEC,
indicate that stratospheric data over the low pressure
center are useful for reconstruction of low pressure in the
Arctic, and also that the data may have impacts onreconstructions in the upper portion of the mid-latitude
troposphere (Inoue et al., 2013). The international
research community has recognized the leading role ofthese results and the impacts of barometers deployed onsea ice, as well as of radiosonde observations over theArctic Ocean. Research groups in Japan can pursue
observations and manage data assimilation systems
independently of operational weather centers, which isnoted by the IASC atmospheric working group as a rarecase with respect to global standards.
b. Ocean-sea ice data assimilation systems
Operational reanalysis of ocean-sea ice states using data
assimilation techniques is now carried out at a few
institutes. One typical example is the Nansen
Environmental and Remote Sensing Center, at which a
regional ocean-sea ice data assimilation system, TOPAZ*,
produces reanalysis fields in the North Atlantic and Arctic
Ocean using the ensemble Kalman filter method. The
other example is FOAM*, a global ocean-sea ice data
assimilation system based on the optimal interpolation
method*, developed by the United Kingdom
meteorological station, the UK Met Office. Both of thesehave been developed on coupled ocean-sea ice models andhave the common objective of providing medium- to longterm forecast and reanalysis data, even though they opted
for different data assimilation methods. Their products,
reanalysis fields, and forecasts are publicized every day
through the portal site, MyOcean.
More research-oriented attempts at ocean-sea ice data
assimilation are NAOSIMDAS* of the project,
DAMOCLES*, and the Arctic Ocean analysis system of
the project, ECCO2*. Both of these adopt the 4dimensional variational method*, and are only two
successful attempts of the adjoint codes* for the coupled
ocean-sea ice model at this stage. At the University ofWashington, the Arctic Ocean sea ice-ocean reanalysis
system, PIOMAS*, has been developed using the optimal
interpolation method, and is considered a semioperational tool. These ocean-sea ice data assimilation
systems have strength in simultaneous assimilation ofobservation data from the ocean and sea ice. Aninteresting outcome of these analyses is the possibility thatsea ice data significantly affect state estimates of the oceaninterior.
Sea ice data assimilation systems have been
implemented in coupled atmosphere-sea ice-ocean
forecast systems. At Environment Canada, the sea ice data
assimilation system was implemented experimentallyusing the optimal interpolation method. The
Meteorological Research Institute in Japan has estimatedc. Sea ice seasonal forecast
We focus on seasonal prediction of sea ice states during
the melting season, in which initial and final denote latespring and late summer, respectively. The correction of
initial sea ice thickness, which is reconstructed fromassimilation of thickness data, improves final ice
thickness distribution (Lindsay et al., 2012). A similar but
more detailed suggestion was provided through thecoupled atmosphere-sea ice-ocean model, CNRMCM3.3*; here, the initial sea ice thickness distribution at
a sub-grid scale contributes most significantly to the final
ice covered area. The reason for this sensitivity lies in thetendency for common volume but different thickness
distributions, with thicker ice over a smaller area
persisting longer than thinner ice over a larger area during
the melting season. If this mechanism to extend sea ice
presence is really effective, initial state correction by
thickness data is expected to play an important role for
improving seasonal forecasts of sea ice.
d. Estimates of atmospheric chemistry components
Ozone in the Arctic stratosphere has been observed forhalf a century, with accumulation of sonde data for 45
years, and of satellite data for 35 years. Analyses of thesedata sets show active inter-annual variability in winter-tospring and also a long-term trend, indicating a relationshipwith atmospheric circulation variability, such as theBrewer-Dobson circulation. As we understand that an
atmospheric chemistry composition varies dynamically in
conjunction with atmospheric circulation, research isadvancing on the basis of coupled physical-chemicalsystems. Chemistry-climate models, composed of
atmospheric circulation models of the troposphere andstratosphere, along with chemical transport models,therefore play an important role in understanding thiscoupled system (Dameris and Jöckel, 2013). Sincechemical data sometimes provide useful constraints forcirculation and mixing, ongoing research anddevelopment are focused on simultaneous data142

attempt estimates of forcing terms and model parametersfrom observation data, using the variational method or the
Kalman filter method.
The data assimilation experiments with altitude data
show that corrections of both surface mass balance (SMB)
at the top boundary and friction coefficient at the bottom
boundary are effective for reproducing variability ofsurface elevation changes over the last ten years or so.
Sensitivity experiments indicate that ice velocity issensitive to the basal friction coefficient and topography,
and hence, we expect that bottom boundary conditions
may be accurately determined from simultaneous
assimilation of surface elevation and velocity data. Froma different perspective, because SMB is usually specified
through outputs of an atmospheric model or reanalysis
fields, an attempt to estimate SMB has been made using
data assimilation in a regional atmospheric model.

assimilation systems combining both physical andchemical models, and on production of reanalysis fields
from the system.
e. State estimates of ice sheets
Since the measurements of surface elevation and ice
flow velocities of the Greenland ice sheet have advanced,
mainly through the use of satellites over the last ten years,
monitoring conditions have improved dramatically. A
quantitative estimate of ice sheet variability is crucial toclimate change research, although an important task is
how to estimate parameters that cannot be observed
directly, such as bottom boundary conditions of the ice
sheet. Data assimilation research was initiated through atwin experiment* using a standard dynamical ice sheet
model (e.g., SICOPOLIS*) and its adjoint equation model(Heimbach and Bugnion, 2009). It is now possible to

Direction of data assimilation research for the Arctic environment
resolution. Since (3) and (4) are related to external forcing
errors, correction of external forcing with data
assimilation techniques is effective, along withimprovement of the accuracy of atmospheric reanalysis
data.
In the process of improving ocean models andobservation systems of the Arctic Ocean, the ocean data
assimilation groups will examine detailed techniques for
production of ocean reanalysis data. In addition to sea ice
cover, bottom topography is specific to the Arctic Ocean,with circulation dominated by flows trapped on the
topography and filled with eddies. To reproduce thiscirculation, high horizontal resolution of numericalmodels is necessary, although there is no hope ofincreasing observation networks in the near future. It istherefore obviously impossible to reproduce oceanicstates to the eddy-resolving scale from observation data,
even if we use data assimilation techniques as an inversion
problem. In this situation, the data assimilation approach,with a basis in regional models, may be useful byimplementing an eddy-resolving observation networkwith a focus on eddy-rich regions such as the Barrow
Canyon. Once we attempt state estimates over the entire
Arctic Ocean, a probably useful method will beparameterization of eddy-driven transport of momentum,
salinity, and temperature, with another being reduction in
the order of model state using EOF mode expansion.
Following significant achievements in the physicalenvironment, we are going to implement material
circulation (i.e., biogeochemical) models and marine
ecosystem models. We will then sequentially tackle
production of reanalysis data and initial conditions forforecast, suggestion of optimal observation networks, andstate estimates of material circulation and marine
ecosystems. Collaboration with specialists in material
circulation and marine ecosystems seems promising for
producing significant scientific outcomes in multi-fielddata assimilation; this is because, these specialists in Japanare considered to be world-class. The four-dimensionalvariational method is suitable for material circulation,
which is expected to satisfy tracer conservation (whereas
nonlinear behaviors often create problems in parameter
estimates). It has been suggested that the genetics
algorithm* and the Green function method* are useful as
auxiliary techniques for parameter estimation in the case

The Arctic is one of the most difficult areas formonitoring of the climate system, due to its special
climate and geography. The applications of data
assimilation technology and successful cases introducedin Section 2 indicate the possibility of overcoming thisdifficulty, through integration of observation data sets andgoverning laws for targeted systems. In this section, we
propose the further development of data assimilation
techniques presented in Section 2 for monitoring theatmosphere-sea ice-ocean system. We then propose theextension of data assimilation techniques to the multisphere climate system including the marine ecosystem, ice
sheets, and terrestrial vegetation. The other item to discuss
here is establishing operational weather and oceanic
forecast systems, which are required for safe and secure
economic activities in the Arctic under conditions of rapid
climate change, and the implications of the latter (such asa decrease in the sea ice area).
a. Data assimilation for the ocean
As explored in AOMIP* and other research, the Arctic
ocean circulation and sea ice state produced in coupled
ice-ocean models suffers from large deviations fromobservations; and there are also wide variations between
models as compared with mid-latitude models. Coupled
ice-ocean models therefore need to be improved toprovide accurate reanalysis fields for the Arctic Ocean.
Although it is impossible to list here all causes of model
error due to combinations of complex factors, some ofthese have been well identified, along with theirtreatments, as follows: (1) low model resolutions, (2)representativeness of temperature and salinity data under
sea ice, (3) errors and biases in ice-ocean heat fluxes, and(4) errors and biases in external forcing data.
Item (1) will be resolved through continuous
improvement in the ability of computers. A necessarycomponent to resolve (2) is implementation of Argo*-type
floating buoys with mobility and data transmission
capabilities even under sea ice cover. In addition todeveloping observation systems, as proposed in Theme A,
data assimilation research should also take place for theoceans and sea ice. The data assimilation community
should play its role to establish an optimal observation
network, through sensitivity analyses of observation
systems using a coupled ice-ocean model with high143most suitable data assimilation procedure for forecasts isachieved through the regional coupled atmosphere-sea
ice-ocean model, by examining what data are suitable forthe forecast.
Large errors exist in estimated heat and freshwater
fluxes between the atmosphere, sea ice, and ocean in the
Arctic (Bourassa et al., 2013). These fluxes determine theboundary conditions in coupled ice-ocean andatmospheric models, and hence, biases and errors in fluxes
directly limit the simulation and forecast abilities of themodels. The lack of observation data is one error source,
but cannot be immediately resolved by better observation
techniques, because the gap is related to climate
conditions and the geographic environment. The
necessary approach to solve this problem is production ofreanalysis flux data that maintains physical consistency,
which is guaranteed by the atmosphere-sea ice-ocean data
assimilation system. We hope to initiate a research project,taking advantage of the dominant position of Japan, basedon an atmospheric model and a coupled ice-ocean model,
as well as corresponding data assimilation systems.
When the time scale of analysis exceeds a decade, theprediction of mass loss from the Greenland ice sheet
becomes important. To estimate surface mass balance of
the ice sheet as a result of snowfall, refreezing, andmelting on the surface, we propose using surface elevation
data of the ice sheet and also assimilating the data to an
ice sheet model, along with improving the baseatmospheric model. We should design a data assimilation
procedure with extreme caution with regard to thecharacteristics of the basal friction coefficient, which
reduces under a melting bed condition and has a nonlinear
relationship with basal sliding speed. In addition to fast
ice flow over a melting bed, we should also look at
significantly large ice sheet mass loss near the boundarywith the ocean. Data assimilation is hence supposed totake into account the coupled ice sheet-ocean model,
which is just starting to be developed. We expect many
obstacles to data assimilation for these coupled models,caused by the variety of model accuracies and dataamounts; however, undertaking this challenge constitutes
a worthy long-term plan.

of strong nonlinearity.
b. Data assimilation for sea ice
The purposes of sea ice data assimilation are
categorized as follows: (i) providing lower boundary
conditions to atmospheric models, (ii) providing upperboundary conditions to ocean models, and (iii) short- andmedium-term predictions and long-term reanalysis data of
sea ice itself. To improve predictions and reanalysis dataof sea ice, the optimization of initial conditions andboundary conditions plus external forcing is required,along with higher quality of basic numerical models. Dataassimilation techniques can play a major role in thesetasks.
Most sea ice models have internal dynamics orrheology in the form of viscous-plastic or elastic-viscousplastic, the latter more appropriate in the case of high sea
ice concentration. For the marginal ice zone withconcentration less than 90%, more appropriate laws havebeen suggested. One of these is a pack ice model, theinternal dynamics of which are represented by loose
collisions between ice floes, with a model variable being
the distribution function of an ice floe size. A newly
developed model often has parameters to be determinedfrom observation data, and data assimilation cancontribute to optimization of parameter values. This
combination of observations and data assimilation
techniques is expected to work on optimization ofparameters included in momentum and heat fluxes within
the air-ice and ice-ocean systems, and then, leads toimproving sea ice models and resultant prediction skills.
Observation data that will contribute most significantly
to the sea ice data assimilation system are sea ice thickness
and concentration, which are estimated from datacollected with spaceborne sensors. The algorithms for sea
ice state estimates will be improved using ground truthingwith field data, as introduced in Theme A. The polar
research community in Japan has a reputation fordeveloping algorithms for translating satellite data to sea
ice states in the Arctic Ocean and in marginal seas withseasonal sea ice zones (Okhotsk Sea and Bering Sea).
Taking advantage of this, the data assimilation researchers
should actively collaborate with satellite observation
researchers, making significant contributions to thetechnology of sea ice state estimates. As the outcome ofthis technological advancement, more accurate initialconditions will contribute to short-term and seasonal
forecasts of sea ice cover.

d. State estimate for marine primary ecosystem
It is expected that marine ecosystems will be underhigher stress due to a sharp decline in summer sea ice
cover, urging us to establish a monitoring system and to
explain the variability mechanisms (see Theme 9 fordetails). Coupled ocean-sea ice-ecosystem modeling has
to be used to supplement sparse monitoring of the marine
primary ecosystem over a wide area. For the state estimateof Arctic ecosystem responses, which are controlled by
the seasonality of sea ice, model ice cover is required toagree with retreat timing of the observed ice edge.
Improvement of physical models is necessary, while oneof the approaches is to use assimilation of sea ice data.
However, in cases when oceanic stratification is crucial, afreshwater flux from ice melting has to be correctly
represented in addition to shortwave radiation. We have toremember that the freshwater flux tends to include a
substantial bias caused by the nudging method for data
assimilation. Even if the physical field is absolutely
correct, model results of biological variables are
dependent on the reliability of ecosystem models. Moreaccurate states are achieved by improvement of both
physical and ecosystem models and also by optimizationc. Data assimilation for the coupled atmosphere-sea
ice-ocean-ice sheet system
For forecast of the Arctic atmosphere-sea ice-oceanstates, an important research theme is developing
operational data assimilation and short-term forecast
systems with a focus on the Arctic area, by establishing abasis in numerical models with initial and boundary
conditions consistent with observation data. The basicmodel is selected from regional coupled atmosphere-sea
ice-ocean models, the configurations of which have been
optimized for the Arctic, as shown by Polar-WRF. Here,the parameterization schemes should be suitable forphysical processes in the polar region; it is then also
crucial to adjust parameters consistent with observation
data, using data assimilation techniques. Since accuracyof initial conditions is a key to a precise short-term
forecasts, the Kalman filter method may be useful. The
144

dimensional variational method based on a time-varying
equation for dissolved inorganic carbon (DIC) in theeuphotic layer, and estimated spatio-temporal
distributions of the air-sea CO2 flux by assimilating
carbon dioxide partial pressure (pCO2) data in the ocean
surface layer. In this experiment, they used reanalysis
fields of temperature and salinity, which are needed forocean circulation and parameterization of the air-sea DIC
flux formulae, and the control variable was an initialcondition. For application to the Arctic Ocean, we have tocarefully examine the assumption of unifying governing
equations for a DIC model. The other issue is related to
pCO2 data, which is limited to summer ice-free areas in
the Chukchi and Barents seas. To solve this problem, we
expect year-round monitoring of pCO2 under sea ice cover,which has now been experimentally attempted using ITP.
Large-scale monitoring of the air-land carbon flux in
the Arctic has been carried out, relying on spaceborne data
along with a land carbon flux model (Kimbell et al., 2009).
The carbon flux model is composed of the production
efficiency model (PEM), which is a diagnostic model, andestimates carbon dioxide uptake by vegetation fromspaceborne data. The resultant air-land carbon flux isverified against in situ data collected at flux towers, so thatmodel parameters may be optimized. This procedurerequires that weather elements are supplied fromatmospheric reanalysis data, along with spaceborne data.
Even over land, reanalysis data contains non-negligible
uncertainty, affecting uncertainty in the carbon flux. Since
atmospheric reanalysis data can be corrected sequentiallywith flux tower data using data assimilation techniques(such as the Kalman filter method), these techniques could
improve the accuracy of carbon flux estimates.

of model parameters using data assimilation techniques.
As an example, in Japan, the optimal parameters of the
primary ecosystem model, NEMURO*, are estimatedglobally by taking chlorophyll data of SeaWiFS* andnutrient data in World Ocean Atlas (WOA) (Toyoda et al.,2013). The tasks to be carried out for applying data
assimilation technology to marine ecosystem models arelisted below.
First, we list tasks for improving reproducibility of basemodels. AOMIP for Arctic ecosystem models pointed outthat the variety in mixed-layer depths is responsible fordifferences in primary productivity among the models(Popova et al., 2012). Main plankton species and nutrient
components are expressed in most Arctic ecosystemmodels, including ice algae unique to the polar ocean;
however, important elements such as denitrification,
nitrogen fixation, and iron-restriction, which constitutecrucial differences between regions, have not been
properly included in ecosystem models. Since this issue is
not relevant only to the Arctic Ocean, the necessary
elements should be developed by referring to theknowledge provided by mid- and low-latitude modelstudies. Please see Theme B for various elements to
produce this bias.
The next issue is validity of the data set to be used fordata assimilation. Observation data sets usually havevarious acquisition periods: e.g., chlorophyll data by
SeaWiFS are prepared over the time series 1997–2010,
while WOA retains only climatic values; cost functions
hence have to be carefully designed to utilize different
types of information. Spaceborne chlorophyll data havelarge biases in the polar ocean, and need to be dealt withusing caution for data assimilation. Enhancement andaccuracy of observation data directly contribute to theutility of data assimilation products; we hence require
collaboration with field research scientists.
Since ecosystem models have much more variables andparameters than physical models, an important work is toselect and prioritize parameters to be optimized so thatcomputer resources may be spent efficiently. Optimized
parameters include not only a maximum photosynthesis
rate and a half-saturation constant of nutrients, but also a
re-suspended nutrient flux from bottom sediments. A
meaningful data assimilation product requires evaluationof whether estimated parameters are within realistic
ranges.

f. Data assimilation for Arctic terrestrial vegetation
In the Arctic area, as air temperature rises due to global
warming, vegetation becomes more active in some cases,
while it declines in other cases because soil moisture is
reduced by permafrost melting (see Theme 8). As a result,
there are impacts on wildlife and then on the lives ofresidents (see Theme 7). To assess the regional effects ofvegetation variability under climate change, we need to
predict the distribution variability of individual plant
species, which are dependent on terrain and soil
conditions. Growth and mortality of terrestrial vegetation
are dependent on atmospheric conditions, solar radiation,and soil moisture, and the dependency is described as adifferent function for each species. The functions areconstructed by empirical laws induced from observation
data and include many uncertain parameters. The
uncertainty should be minimized for future prediction.
In cases when many parameters are simultaneously
estimated using data assimilation techniques, insufficient
observation data may lead to some parameters being illposed: i.e., optimization falls into a local minimum, andhence some parameters are not determined. Given thecurrent state of data assimilation studies for terrestrial
vegetation, seasonal variability in vegetation isreproduced as a spatial average, by assimilating net carbon
dioxide exchange, gross primary production, daily mean
total respiration, and carbon stocks to an ecosystem Box
model, with a reduced number of parameters. For cases
when spatial distribution of vegetation is predicted underclimate change conditions, we need to reproduce decline
and growth of multiple species in an ecosystem model,
and hence the way should be paved to simultaneouse. State estimate for carbon cycle in the Arctic
As the ice-free area expands, observation results show
an increase in carbon absorption in the Arctic Ocean. A
temperature rise over the land surface enhances vegetation
products in high-latitude areas, and the vegetation area isreported to expand northward in some regions. The carbon
cycle is hence predicted to strengthen over the coming
several decades in the Arctic area. To understand thebackground principle of climate change, a carbon cycle
monitoring system is expected to be established as soon as
possible. We need optimal integration of a limited numberof observations with numerical models using data
assimilation techniques, so that the carbon cycle may be
estimated quantitatively, in the same way as state
estimates of the coupled atmosphere-sea ice-ocean system.
State estimates of the air-sea carbon dioxide flux havebeen carried out successfully using data assimilation
techniques. For example, Valsala and Maksyutov (2010)
constructed a data assimilation system with a four145

contribute significantly to optimization of surface
parameters and hence improvement of atmosphericcirculation models.

optimization of many parameters.
A database on responses of various plant species to theenvironment has been built, based on field investigationsin Hokkaido, Alaska, and Siberia (see Theme 8),
providing conditions for applying data assimilation
techniques to vegetation models. Next, we will start toconfirm that the techniques are useful for optimization ofmodel parameters associated with a particular species.
Then, once this utility is confirmed, we will challenge data
assimilation with a coupled ecosystem-soil-atmospheremodel, which is specific to optimization of fluctuation
processes of various plant species and the atmosphericboundary layer. This plan requires a complete observation
network, dataset arrangement, adjustment of appropriate
complexity in an ecosystem model, and selection ofparameter estimate techniques, and hence an
indispensable condition is collaboration between
specialists in data assimilation techniques and specialists
in field investigation and ecosystem modeling.

h. Short-term forecast of sea ice and surface layer
currents along the Arctic Sea Route
The Arctic Shipping Route, composed of the Northeast
route on the Russian side and the Northwest route on the
Canadian side, is now partly operational. To secure safetyof ships through the Arctic Shipping Route, it is necessary
to accurately predict cyclone paths, wind waves, and sea
ice states for up to a week, and also to deliver the
information to ships. A coupled sea ice-surface ocean
model with high spatial resolution is needed for accurate
prediction of the Arctic Shipping Route. The model thatcan provide a basis for data assimilation and short-term
prediction is a coupled atmosphere-sea ice-ocean regionalmodel with high resolution, which is specific to the Arctic
Shipping Route, using a dynamic downscaling method forboundary conditions constructed from reanalysis data of
the Arctic atmosphere-sea ice-ocean model. If reanalysis
fields do not exist or are not usable, we have to start with
development of a large-area analysis system. Considering
the need for an operational forecast system to deliver
forecast results within a certain time limit (e.g., six hours),
the analysis system has to use a data assimilation methodwith light computational load, such as the nudging method
and the optimal interpolation method. In addition, along
the Arctic Shipping Route, we need to be aware of fast ice
typical of coastal regions and the effects of wind waves
generated by cyclones. It is hence important for a longterm plan to prepare to introduce these aspects into data
assimilation systems, along with investigation of dataacquisition.

g. Data assimilation for the atmosphere
Numerical weather forecast demands over the Arctic
Ocean will increase in response to sea ice decline, because
the forecasts of cyclone paths and sea ice motion play amajor role in keeping safety of ship navigation forgrowing traffic along the Arctic Shipping Route. In
addition, extreme weather events in mid-latitude areas
have large socio-economic impacts, increasing associatedwith polar amplification of the global warming. A
necessary element for more accurate predictions lies in
research on the location and frequency of data collection
contributing to improvement of initial conditions based ondata assimilation. A research group in Germany is keen to
carry out observing system experiments by combining
radiosonde data collected from a German ice breaker and
the Japanese data assimilation system, ALERA2 to the
Arctic cyclone that contributed to sea ice reduction in
2012. The group in Japan has thus started to be at theforefront of atmospheric data assimilation in the Arctic.
This activity is considered a pilot study for MOSAiC*,
which is planned for 2018–19 and will definitely form abasis for Arctic research in the near future.
The development of a data assimilation system whichties with the Arctic regional atmosphere model will
become important, in response to arrangement ofobservation networks in polar regions. In this approach,the regional model has boundary conditions taken from a
global atmospheric reanalysis system, while it is desirable
to include sea ice as a part of a coupled atmosphere-ice
model. In addition, by following the suggestion given by
Inoue et al. (2013), it is important to examine an optimal
observation system for estimates of atmospheric states,
through inclusion of sea ice.
Triggered by data accumulation due to intensive
observation campaigns, we need to reconsider aparameterization scheme for air-ice fluxes, with crucial
effects on the lower boundary layer of the Arctic
atmosphere. An example is found in the roughness of theatmosphere being dependent on sea ice concentrations, as
the ice surface state is influenced by ridges and freeboard.
Considering that melt ponds spread due to global warming
and modify radiation fluxes, the albedo scheme is also
being re-examined. Since data are widely collected withspaceborne sensors for physical conditions from the ice
surface, data assimilation systems are expected toi. Wind wave forecast in the Arctic coastal area
As ice cover declines and cyclones become stronger,
more active wind waves are observed along the coastal
region in the Arctic Ocean. Accurate wave informationmust be provided for safe navigation along the Northern
Sea Route, which is expected to be used for commercial
voyages. Wind waves are important factors controlling iceedge distribution, and hence, an ice cover forecast needs awave forecast. The Norwegian Mohn-Sverdrup Center isactually carrying out WIFAR*, a project of wave
forecasting for improving ice edge detection skill. An
operational wave forecast system is indispensable also forproviding forecast information of coastal erosion caused
by wind waves to residents who suffer from this problem.
Wave forecast systems have been operated for a long timein low- and mid-latitude areas. It is therefore considered
to be useful and reasonable to extend these systems to the
Arctic Ocean.
The wind wave research group is relatively small inJapan and is not fully experienced in data assimilation.
Given this situation, we will start modeling research andverification of model results for the Chukchi Sea and thecoastal region in the Canada Basin, where we have been
performing intense observations. We will concentrate on
examination of the necessary items for wave forecast: i.e.,model accuracy, observation datasets to be used for initialcondition estimates, etc. After this step, we need toproceed toward development of a forecast system basedon data assimilation technology, step-by-step.

146

Arrangement of basic conditions for Arctic data assimilation researchtypes of data to be stored, the file formats, and theimplementation methods of interfaces for application,
calling for active participation from the observation
community. On the other hand, field observation data areoften managed by institutes and researchers as their own
research assets, and it is hence critical to build individual
relationships for application to data assimilation. By
keeping this point in mind, we need to develop aframework of mutual cooperation between data
assimilation and observation communities.
We discuss errors in observation data as a problem
common to data assimilation research. Although the errors
strongly affect assimilation system behaviors, error
estimates have not yet been sufficiently performed. Thissituation may be related to the fact that uncertainty
estimates of data have to be examined for respective data
sets separately, because of no merits of multi-disciplinary
collaboration. However, we should actively challenge
uncertainty estimates, which constitute an important
technical problem forming a core element of data
assimilation. In particular, in the case of assimilating
multiple kinds of observed values, we need the relative
uncertainty estimate of each value. Here, errors are
categorized into measurement errors caused byinstruments, and representative errors due to sparse
observations and numerical model capabilities. In practice,since representative errors are harder to estimate than
measurement errors, it is necessary to propose anobservation plan to provide statistical information on
representative errors, through verification of model
outputs against observation data.

To carry out the data assimilation research described in
the previous section, it is also important to arrange basic
conditions within Japan. We focus on three points: how tomake active use of limited human resources, how toprovide observation data as a basis of data assimilation
research, and how to respond to expected technical issues.
The Arctic research community in Japan, having
limited experience in data assimilation research, needs todevelop close cooperation with and receive timely advice
from agencies that are developing assimilation technology.
It then needs to implement models for the Arctic area toassimilation systems. Having a view of various futureapplications, it is desirable to concurrently implement
multiple assimilation techniques, although this is adifficult task when considering domestic human resource
constraints. It is therefore necessary to select anappropriate technique for each application so that we may
concentrate available human resources. It is also
important for the atmospheric and oceanographic
assimilation research communities, who have madeadequate progress in assimilation research, to support thedissemination of this technology to other disciplines
through workshops and summer schools.
Since a wide variety of observation data are available
for data assimilation in the Arctic, it is not realistic toaccumulate and archive data only for data assimilation
purpose. We therefore adopt the strategy of using existingdata archiving systems for data accumulation andproactively make recommendations with respect toobservation data storage among the data assimilation
research community. In practice, we will clearly convey
the requests of the assimilation community regarding theTable 3 Explanation of terms

Term
ALERA2: AFES–LETKF
ensemble reanalysis

experimental

AOMIP:
Arctic
Ocean
Intercomparison Project

Model

Explanation
The data set from experimental ensemble reanalysis of atmosphere
during the period of January 1, 2008 to January 5, 2013, made publicby Earth Simulator Center
The model intercomparison project of the Arctic Ocean models carriedout in the period from 1999 to 2011, aiming at exploration of problems
and improvement of reproducibility by making model setting ascommon as possible
Automated floating buoys to monitor oceanic fields, measuring
temperature, salinity and others along trajectories of sea water andcommunicating at near real time

Argo
ASR: Arctic System Reanalysis

Atmosphere reanalysis data produced from the high resolution version
of Polar-WRF using data assimilation system optimized for the Arctic

CBHAR: Chukchi-Beaufort Seas HighResolution Atmosphere Reanalysis

Atmospheric reanalysis data with high resolution specified for the
Chukchi Sea and the Beaufort Sea in the period of 1979 to 2009, using
the data assimilation system WRFDA on the basis of Polar WRF

CNRM-CM:
Recherches
Model

CentreNationaldeMe´te´orologiques-Climate

Climate system model developed for CMIP mainly by National Centre
for Meteorological Research, Meteo-France

147

Term
DAMOCLES: Developing Arctic Modelingand Observing Capabilities for Long-term
Environmental Studies

Explanation
Project led by Europe for understanding Arctic climate variability,
including SEARCH which manages Sea Ice Outlook, project forseasonal sea ice forecast

ECCO2 : Estimating the Circulation andClimate of the Ocean Phase 2

Ocean research project established in 1998 as part of WOCE, with apurpose of coupling modeling and observation, participated by JPL,NOAA, MIT and Scripps Institution of Oceanography

FOAM: Forecasting Ocean Assimilation
Model

IAU: incremental analysis updating

Ocean-sea ice data assimilation system developed by the United
Kingdom meteorological station, the UK Met Office, with operational
components for global, North Atlantic, Mediterranean and Indian
Ocean
The technique to incorporate increments into model integration in a
gradual manner, using analysis increments as constant forcing in a
prognostic equations of the model, along with estimation of initialconditions

ITP : Ice Tethered Profiler

Automated censors deployed on sea ice with wire hanging down tomeasure water temperature, salinity and others, communicating at nearreal time

MITGCM: MIT General Circulation Model

Numerical model of atmosphere, ocean and climate, developed by MIT

MOSAiC:
Multidisciplinary
drifting
Observatory for the Study of Arctic Climate

Research plan prepared by IASC, the atmosphere working group to
operate drifting observatory in the middle of the Arctic Ocean, aiming
to start in 2018-2019

NAOSIMDAS: North Atlantic/Arctic
Ocean Sea Ice Model Data Assimilation
System4-dimensional variational data assimilation system as part of
DAMOCLES, on the basis of coupled ice-ocean model developed by
Alfred Wegener Institute

NEMURO: North Pacific Ecosystem
Model Used for Regional Oceanography

Low-level ecosystem model developed by the North Pacific Marine
Science Organization (PICES), originally for the North Pacific but
now also for the global and Arctic Ocean

PIOMAS: Pan-arctic Ice-Ocean Modelingand Assimilation System

Coupled ice-ocean model developed by University of Washington,with optional data assimilation system of nudging sea ice
concentration toward satellite data

Polar-WRF: Polar Weather Forecast Model

Version of WRF specified to the polar region developed by Byrd Polar
Research Center, Ohio State University

RIPS: Regional Ice Prediction System

System developed by Environment Canada for regional sea ice
analysis and forecast, used for operational analysis of sea ice
concentration with 3-dimensional variational data assimilation method

SeaWiFS: Sea-Viewing Wide Field-ofView Sensor
SICOPOLIS: Simulation COde for
POLythermal Ice Sheets

Satellite sensor for ocean color to estimate amount of chlorophyll

TOPAZ: Towards an Operational Prediction
system for the north Atlantic european
coastal Zones

Operational prediction system of regional ice-ocean in the North
Atlantic and Arctic Ocean developed by Nansen Environmental andRemote Sensing Center using ensemble Kalman filter method

WIFAR: Waves-in-Ice Forecasting for
Arctic Operators

Project to assess the effects of waves on ice-ocean fields near the iceedge conducted by Mohn-Sverdrup Center

WRF: Weather Research and Forecastingmodel

Next generation mesoscale weather forecast system for atmosphericresearch and weather forecast

WRFDA: WRF Data Assimilation system

Data assimilation system for atmosphere based on WRF

WWRP-PPP: World Weather Research
Programme-Polar Prediction Projects

Project led by WMO for assessment of prediction capability of the
Arctic area

Three-dimensional dynamic-thermodynamic model for simulation oflarge-scale progression of ice sheet

148

Term
Adjoint code

Explanation
Model code formulating the gradients of the cost function necessary ina variational data assimilation method, being derived as the adjoint
operator associated with the model operator in a linearized governing
equation

Ensemble Kalman filter (smoother)

Method to replace time dependent equation of error covariance matrix
with ensemble average of model variables in Kalman Filter (Smoother)

Genetics algorithm

One of the optimal search techniques, using the process similar toevolution for a search process, being capable of search with strongly
nonlinear phenomena

Kalman Filter (KF)

One of the data assimilation techniques, proceeding with prediction ofboth numerical model variables and their error covariance matrix, used
for initialization of a numerical prediction system

Kalman Smoother (KS)One of the data assimilation techniques, with the principle common to
KF which includes previous data, but including both previous and later
data for analysis, used mainly for production of reanalysis fields

Green function method

One of the optimal search techniques for a cost function, using finite
difference approximation instead of adjoint code to formulate thegradients of the cost function

Optimal interpolation method

One of the data assimilation techniques, adding model prediction andobservation data, with the relative weights determined fromobservation operators and error covariance matrix

Nudging

One of the data assimilation techniques, nudging model variables
toward observation data and producing analysis fields

Twin experiment

One of the evaluation methods for data assimilation system, taking
data from the output of the same model as the evaluated model

149

Chapter 9: Improvement of Research foundation
There are various frameworks and equipment required
to follow through with the research themes we havedescribed above, and we provide a description of theserequirements for each theme in prior to this chapter. We

have re-organized the following to represent the research
infrastructure which has the greatest cross-cutting utility,
and which we believe is appropriate for our domestic
community of researchers to be ready for our use.

Ice-Breaking Observation Vessel
water, invigorated biological activity throughphytoplankton, the effects of inflow on rivers etc. Without
understanding the mechanisms behind these phenomena,
it will not be possible to predict the effects on
atmospheric/oceanic cycles and climate change that
accompanies a reduction in sea ice, nor the responses ofmaterial cycles and marine ecosystems. To understandthese phenomena at their locations, process research is
required that takes a perspective on atmospheric/sea
ice/oceanic heat budgets, as well as ecosystems andmaterial cycles; thus, it is indispensable to having data
gathering on location that spans all seasons. Additionally,in predicting the state of the Arctic Ocean and the ice sheet
as warming continues, it is important to reconstruct the
distribution of sea ice and the terminal position of the ice
sheet in the Arctic Ocean as it is currently versus
conditions of radically different climate conditions and tounderstand the various mechanisms behind these changes.
To carry out the above, it is absolutely essential toassess the status of erosion and sedimentation on theseafloor through topographical analysis of the Arctic
Ocean bottom and to extract sediment samples from awide area. Additionally, to further understand long-term

There are a plethora of anticipated uses for an ice
breaker: from shipping materials to undersea resource
exploration. In this section, we will outline the necessityof the observation infrastructure rightly referred to as a
'Research-Specialized Ice-Breaking Vessel', which is
deeply-rooted in polar atmospheric and oceanic research,
including seafloor exploration (As a matter ofconvenience, we will refer to these vessels simply as
icebreakers in this document.).
Explaining the mechanism behind sea ice fluctuation in
the Arctic Ocean is an urgent issue to understanding the
global climate system, and is indispensable to improving
the accuracy of forecasting the future of Arctic sea ice. A
dramatic reduction of sea ice up to this point has been
observed primarily on the Pacific Ocean-side of the Arctic
Ocean, which has shown marked ocean warming;
however, the phenomenon of seasonally-variant sea ice
continues to advance throughout the Arctic Ocean.
Generally, the regions with seasonally-variant sea ice,including the marginal ice zone, contain numerous
fascinating physical and biogeochemical phenomena,such as atmospheric-oceanic heat exchange, thetransportation of substances via sea ice and high-density

Table 4: The concrete objectives of having its own icebreaker for various observational activities

Atmosphere

Ocean and ice

Ecosystem

Solid earth
Paleoenvironment
Paleoclimate

Improvement of weather forecast accuracy in the mid and high latitude area by aerologicalobservations over the sea ice coverSupply of meteorological information for shipping on Arctic sea routes
Flagship to build big international projects such as MOSAiC
Drastic improvement of the degree of freedom (flexibility) for selection of observation periods
and regions
Implementation of sea ice observations all year-round (importance of observations over the icecovered area during winter)
Realization of field observations of physical and geochemical processes in the sea ice growing
and decaying periods (including wintering observations on sea ice)
Realization of observations synchronizing with no-ice area observations (in cooperation withexisting ice-class vessels)
Improvement of reproducibility of coupled ice-ocean models (essential for shipping route
prediction)
Realization of biological observations from the sea surface to bottom without effects of sea ice
presence
Establishment of all year-round observation systems of marine ecosystem (impossible undercarpool systems of icebreakers between countries)
Establishment of observation sites of marine ecosystem
Improvement of reconstruction accuracy of the distributions of sea ice and ice sheets in past
Improvement of accuracy of bathymetric maps
Exploration of hydrothermal systems along seafloor spreading centers under sea ice cover
Estimation of internal structures below the seafloor of the Arctic Ocean
Preliminary survey for progress in paleoenvironmental and paleoclimate research and largescale excavation in future
Estimation of the formation process of the Arctic Ocean
150

Japan will dramatically expand the potential of Japanese
Arctic research. The specific implications of possessing
our own icebreaker for various observational research
activities have been summarized in table 4.
Should Japan build our own icebreaker the Arctic
Ocean, the Antarctic Ocean, and the Sea of Okhotsk will
all become available to serve as potential operating
regions. However, to actually sail through ice zones formany years, the icebreaker must be outfitted with theappropriate specifications. To carry out Japan's own
Arctic research, an icebreaker must ultimately be
specialized for academic research purposes; however, an
operational regime must be built that also allows it toflexibly respond to various societal demands. Other
factors to continuously operate an icebreaker must also be
kept in mind, such as a crew, equipment and assembly ofan operating system. Sea ice has been predicted todisappear completely during the summer season in the
Arctic Ocean by the 2030s at the earliest; however, there
is an extremely low possibility that there will be no sea ice
in the Arctic Ocean throughout the year, including during
the winter, and we do not anticipate future conditions
where an icebreaker would not be required. To go beyond
being simply an icebreaker and actually function as a
Research-Specialized Ice-Breaking Vessel, the following
equipment will be required: a moon pool, a satellite data
receiver system for the Sailing Plan, CTD observation
system and storage racks, A-frames, winch withmultipurpose cable, automatic radio sonde launcher,laboratory for chemical, biological and geologicalanalysis (including refrigerator), a low/wide/long
vertically-opening observation gunwale on the same level
as the laboratory, a workshop to handle maintenance of all
shipboard equipment, an AUV with multiple sensors andthe ability to operate for extended periods underneath sea
ice, an ROV with the ability to take samples, a long, largediameter piston corer, a large crane to lower the corer fromthe gunwale, a multi-beam depth sounder to be used insurveys of seafloor topography, sub bottom profiler for
stratum exploration, equipment to estimate tectonics andthe inner structure of the Earth, such as a gravimeter anda magnetometer. Additionally, the icebreaker would be
ideally equipped with seafloor-based drilling equipmentthat can take longer deposit samples from the moon pooland either reflection or refraction seismic survey
equipment, should the need arise for such.
By possessing our own icebreaker, Japan will be able toconduct original mission-oriented research. For example,
observational research will be enabled that aims at
understanding specific processes in important marine
regions. Additionally, by basing projects on a platform,
there will be further involvement and advancement
expected from Japanese researchers in numerous polar
research fields (atmospheric sciences / sea ice /oceanography / paleooceanography / paleoclimatology /paleoenvironmental sciences / solid Earth physics;
biology/physics/chemistry). Proposals for international
research projects will also be possible without sufferingfrom the constraints of national borders. If a system is put
in place that accepts foreign crew members, such as withexisting research vessels, then this not only promotes
transnational collaborative research, but also allows forthe development of research on a par with the rest of thechanges, it will be necessary to investigate the tectonics ofthe Gakkel Ridge, which is currently expanding the ocean
bottom, as well as the formation process of the Arctic
Ocean and the inner structure of the Earth; and, there will
also be a need to understand the interaction of solid Earthdynamics with the uppermost stratum environment inconjunction with the paleoenvironmental / paleoclimatic
research on deposits. In sum, the procurement ofobservational infrastructure - specifically, an icebreaker to obtain data and samples on location is of the utmost
importance to advance Arctic research.
Japanese research expeditions to the Arctic Ocean have,up to this point, been carried out using Japanese iceresistance ships or icebreakers from other countries, andthese operations have been constrained by expedition
timing, operating area, the number of participants andbudget. There are problems associated with the use of
icebreakers from other countries in particular that cannot
be overlooked; for example, not only is there the constantrisk of interference with the Japanese research agenda via
the political tendencies of other countries, but there is also
the issue of transporting (exporting/importing) samples,
research equipment and materials. This has become aparticularly large hindrance in limiting the types ofresearch materials and data amounts for chemical andbiological research needed in on-site analyses andexperimentation. In contrast, countries that possess
icebreakers already have research regimes in place, andhave been vigorously carrying out their research programs.
If nothing is done, Japan will fall behind in promoting
research of the critical area where we need to understandchanges of the Earth's systems in recent years. For Japanto further develop its own Arctic research, we must have
our own icebreaker which can be flexibly adjusted tomatch the research expedition timing and region; and,Japan must have in place our own trans-seasonal(including overwintering) regime that utilizes anicebreaker as a platform to engage in on-site research(including on ice), as a manned-observation station, andas a base to carry out unmanned observation (including
with AUVs).
There has been little accomplished by other countries
with serious observation in the seasonal sea ice areas,
including along the marginal ice zone. Japan, which has
already carried out much research, in not only the Arctic
and Antarctic Oceans, but also in the seasonally-variant
sea ice regions of the Sea of Okhotsk and the Bering Sea,
possesses significant potential for further process
investigation by deploying our own icebreaker to carry out
our own original observational research. Moreover, thecombined use of our existing ice-strengthened vessel with
an icebreaker would allow for observations to have asurface-based understanding of the ice-forming
preconditions in the sea-ice zones, the marginal ice zones
and the open water zones, along with year-roundobservation of atmospheric/sea ice/oceanic heat balance.
There is also great significance to Japan possessing its
own icebreaker since we will be expected to take a largerole in the preliminary survey and drilling research for theinternational research drilling in the Arctic Ocean
currently under discussion towards being carried out by
the IODP (Integrated Ocean Drilling Program), among
others. It is clear that the acquisition of an icebreaker by151

world. Major expectations can also be placed in thewidespread training of new talent, which not only involves

researchers and technicians, but also includes improved
sea-ice navigational skills by mariners.

Satellite Observationbasis.
To monitor mass fluctuations in the ice, Japan will
require our own laser radar altimeter. In addition to the
CryoSat-2 currently carrying out observations, the US isplanning to launch its own ICESat-2; however, the largest
drawback with their altimeter is relatively low spatial
resolution and this disallows analysis of small-scale
fluctuations in ice mass. The acquisition of seamless andhigh-resolution composite altitude data throughcollaborative altimeter readings from a Japanese altimeterand the altimeters of other countries will contribute
greatly to research on global-level fluctuations in thewater cycle through the monitoring of mass fluctuationsin glaciers, ice sheets, sea ice and snow. Additionally, theoutfitting of optical/synthetic-aperture radar (SAR) is
indispensable to monitoring fluctuations in glaciers andice sheets. For example, with high-resolution visual stereo
pair images we can expect significant results in measuring
ice volume changes based on detailed digital elevation
model (DEM). Therefore, the development and launch ofa successor to the ALOS/PRISM is an urgent task.
Moreover, measurement of ice flow velocity throughoptical sensors/SAR is necessary for the monitoring ofchanges in glaciers/ice sheets.
The PALSAR-2 (L-band SAR), which was to be carried
aboard the ALOS-2 due for launch in 2014, is uniquely
different from the SAR satellites of other countries insofar
as it is extremely useful for monitoring glaciers and ice
sheets. ALOS/PALSAR plays the primary role inobtaining data on the ice flow velocity distribution on the
Antarctic ice sheet, and glaciologists around the world
anticipate the same of the data from ALOS-2. Obtaining
high-resolution spatiotemporal data using a Japanesesatellite would be desirable going into the future. Also,
measurement of the physical quantity and albedo of snow
by using optical sensors (wavelength: 19 channels fromvisible to infrared) able to observe the entire Earth at ahigh frequency and resolution scale of 250 m would be
incredibly important to elucidating the processes of snow
accumulation/reduction in both polar regions and theHimalayas as they rapidly change accompanying global
warming. The GCOM-C1/SGLI, due to be launched by
Japan in 2016, will monitor the fluctuating surface andquality of snowy regions around the world and is expected
to contribute to the improvement of land surface processes
for numerical climate models. Furthermore, we should
advance our efforts to evaluate the potential of thedomestic development of satellite gravity measurement
capacity, which has already produced significant results inrecent years with the GRACE satellites.
The high-precision observation of clouds and aerosols
which are largely involved in the Earth's radiation budget
and the water cycle are crucial to explicate climate systemformation in the Arctic region. Certain results in verifying
and improving climate models have been produced
through global observations, carried out both by ISCCP,
which primarily uses geostationary satellites, and thepassive satellites of AQUA with MODIS sensors.

Satellite observations have been made with various
purposes other than environmental monitoring, and also
many kinds of satellite missions have been carried out forenvironmental research, as well as are scheduled in near
future. In this section, the satellite missions only for the
lower portion of the stratosphere are described.
Environmental change at the polar regions, which arekeenly vulnerable to the effects of climate change, isoccurring on various spatiotemporal scales -from thereduction of sea ice, snow and glaciers to changes toecosystems; and, those changes are having an effect on
global climate systems. It goes without saying that asatellite observational network is invaluable if it canconduct concurrent and continuous surface observation in
the remote and inaccessible Arctic region, where thespatiotemporal scales of phenomena are immense. The
scaled-up site observational capacity and thecompatibility with back-up and modelling research will
make a satellite observational network the required
infrastructure for the evolutionary development of polar
environmental research into the future. A satellite
observational network will be a tremendous resource tocreating long-term data, which may be rightly called a'Climate Record', to elucidate the changes of the Earth's
environment -a duty that Japan has taken on through ourleading research on global warming and its effects on
climate change. In the following, we will describe the rolethat a satellite observational network infrastructure
provided by Japan will play in not only research on global
climate systems in the Arctic, but also in helping toresolve the societal problems outlined in the Future Earthplan.
Japan has contributed greatly in the realm of satellite
observational networks up to this point, with therepresentative contribution being the AMSR series.
Japan's microwave scanning radiometer boasts the world's
most advanced performance (AMSR, AMSR-E, AMSR2)
and has taken the place of the United States' SMMR and
SSMI series in currently monitoring the sea ice, snow,
glaciers and ice sheet of the Arctic region. The monitoringof ice on the surface of the Earth not only involves
research on the characteristics of the ice (surface area,
volume, velocity), but also indispensably involves
research on the changes to the heat balance/water balance
between the surface of the Earth and atmosphere as well
as changes to the ecosystem. Currently, no other countries
are involved in the development of microwave scanningradiometer technology, and Japan's role in continuing thisobservation is exceptionally large. Additionally, incomparison with the SSMI series, the AMSR series has
dramatically improved spatial resolution, and has made asignificant impact on polar research. To accurately
analyze changes to the polar region, higher spatial
resolution is still needed; and, the continuous
improvement of resolution and sensors throughtechnological innovation, such as with the doubling (3 to
5km at 89GHz) of the current resolution of the AMSR2 isdesirable to carry out monitoring of polar routes on a daily152

observation network at the National Institute of Polar
Research's Ny-Alesund Base is anticipated to play animportant role as the crucial ground-based verification site
for the EarthCARE satellite.
Concomitantly, the monitoring of the carbon cycle andecosystem changes accompanying global warming are
critical. This monitoring is being undertaken most notably
by the US visible-range (near-infrared/thermal infrared)
sensors MODIS, SPOT Vegetation and VIIRS. Thesesensors observe the properties of the atmosphere (clouds,
aerosols etc.), and are used not only for research into
radiation flux and radiative forcing, but are also important
products for determining the sensitivity of visible-range
sensors. These sensors also permit estimates thegeographic distribution and changes of the leaf area index(the one-sided leaf area per unit ground surface area) andthe length of the growing season from the spring to theautumn, and can assess the annual output, which isimportant for understanding the carbon cycle. Moreover,from the estimated plant seasonality, the formation ofvegetation and distribution of vegetation functional types
in each region can also be estimated. Additionally,
AVNIR-2 and PALSAR aboard the above-mentioned
ALOS have advanced research on changes to land cover,beginning with deforested areas, and estimation researchin forest biomass, one of the carbon stocks in the carbon
cycle. Similarly, in the ocean, while restrictions to depth
observations do exist, visible-range (ocean color) sensors
are the only satellite sensors that allow gathering of thebiological information required for ecosystem monitoring,and contribute greatly to research not only on fluctuations
in chlorophyll a biomass and net primary production
output, but also fluctuations in oceanic phytoplankton
group composition. Further, the development of seawater
optical models has promoted research on the estimation ofcolored dissolved organic matter (CDOM), an important
carbon pool that exists in high concentrations in the Arctic
Ocean. However, as it now stands, we are reliant on US
sensors, and we have fallen behind in immediacy andoriginality. To construct and strengthen a crossdisciplinary cooperative regime in Japanese Arctic
research, we must make use of the skills we gained in thepast ADEOS series, develop Japan's own visiblerange/thermal infrared sensors and continue ourmonitoring. Japan is planning to launch theaforementioned GCOM-C1/SGLI, and this is anticipated
to contribute to research on the ecosystem changes on land
and in the oceans (particularly along coastlines and themarginal ice zone).
The groundwork has already been built in Japanese
Arctic research for the variegated use of satellite
observation; it would be ideal, going into the future, toupgrade sensor functionality, in short, heightened
sensitivity, finer spatial resolution, hyperspectral sensor isneeded. However, to allow for a discussion accompanying
statistical significances, we must continue satellite
observation over the long term based on the same designideals. Additionally, aside from the above-mentioned
global observation satellites, communication satellites,such as tracking/monitoring satellites (most notably the
ARGOS) and the Iridium satellite constellation, areinfrastructural necessities to Arctic expeditions, remoteobservation by buoys, as well as information collection

However, there are limits to the precision of cloud
observation with objects of macroscopic physical quantity,
such as cloud cover, owing to the issues inherent topassive sensors, such as ground surface albedo problems
in the polar regions. To overcome these limitations,observations began in 2006 with CloudSat, a primarily
US-operated cloud-observing satellite equipped withradar, and the lidar-equipped CALIPSO. These satellites,
along with the Aqua satellite, form the so-called 'A-Train'
and follow the same orbital path mere minutes away fromeach other carrying out observations; this kind of satellite
observation makes it easier to carry out analysis using a
combination of multiple satellites. The CloudSat satellite
is equipped with 94GHz cloud radar and allows radarreflectivity factor observation; and, it provides data on
vertically-distributed cloud and precipitation every 1.1km
in the horizontal direction and every 240m in the verticaldirection. The lidar-equipped CALIPSO, can observe in
two wavelengths –visible and near-infrared light—and
can acquire polarized light in the visible spectrum; thehorizontal and vertical differ by upper layers and lower
layers, however, at its finest setting, it provides data every
330m in the horizontal direction and every 30m in thevertical direction. Cloud observation is possible with both
sensors, and analysis of the data they have provided has
allowed for the acquisition of comprehensive information
on multiple layers of clouds not previously available, as
well as information on the relative conditions of ice andwater for each vertical layer. Additionally, through the
combined use of CloudSat and CALIPSO, it has become
possible to investigate cloud microphysical properties,
knowledge of which is indispensable to having aquantitative understanding in the evaluation of influenceson the radiation budget and water budget of clouds.
The dual wavelength backscatter profile anddepolarization rate of the lidar on the CALIPSO has
allowed the calculation of the extinction coefficient foreach type of aerosol, and the lidar's non-albedo-reliant
observational characteristics have been utilized to enable
the extraction of aerosol properties at a high precision on
both land and in the ocean. These satellites are on a polar
orbit and their observation times are fixed. To acquire daychanges and more detailed information, it is important toobserve clouds and aerosols with ground-based active
instruments. The National Institute of Polar Research has
conducted lidar observations at Ny-Alesund, and beganobservations there last year after adding cloud radar witha 95GHz band Doppler function. The GRENE Project isalso planning to carry out intensive observations in thesummer of 2014 involving ground-based observation.
The EarthCARE satellite, scheduled to be launched ina joint Japanese-European mission in 2016, will have a
total of four sensors aboard: the very first Doppler cloudprofiling radar (CPR), high-spectral resolution
atmospheric lidar (ATLID), a multi-spectral imager (MSI),
and a broadband radiometer (BBR). The EarthCARE
cloud profiling radar, through its radar reflectivity factor,
has heightened sensitivity of 7dB greater than CloudSat aswell as a Doppler function, and working with the highspectral resolution lidar function of ATLID, is expected toopen up a path to retrieving new physical quantities, suchas cloud microphysical features, vertical dynamics andcloud particle vertical velocity. The ground-based153

future to reduce economic and time-consuming burdens.
In addition, reducing these burdens would be the same aspurchasing data from commercial satellites, such as
RADARSAT, for Earth observation purposes.

and transmission in real-time. Yet, researchers and others
who actually use these must endure the various costs
associated with their use, such as going through thecontracting procedures and paying high use fees. It would
be desirable to consolidate this into a single process in the

Aircraft Observation
In addition, observations related to solid Earth science,such as airborne magnetic and gravity measurements aswell as laser topographic surveying in the Arctic region,are currently being carried out by countries like Germany,
Canada and Denmark. These observations can be carriedout by using instruments boarded on both rotary-wing andfixed-wing aircraft, but future high spatial resolution dataacquisition would be required using rotary-wing aircraft.
Further, there are few field data in the Arctic region owing
to the accessing difficulty as is the case with Antarctica. It
is expected to enable us on-site geomorphological,
geological investigations and geodetic measurements byintroducing rotary-wing aircraft.
European and US institutions, such as universities andpublicly-funded research institutes, generally own andoperate their own dedicated observation aircraft; however,Japan has yet to reach that status. The National Institute ofPolar Research previously owned a single-engine aircraft
which they used for atmospheric observation in
Antarctica; however, the use of that aircraft finished longtime ago. The atmospheric observations have been carriedout by Japanese research institutes always with rented
civilian aircrafts. This is likely a factor for the lack ofprogress in Japanese aerial observation, and thesignificant delay in the domestic development of airborne
observation instruments in comparison to Europe and the
US. Therefore, the establishment of a system for Japan toown and operate our own observation-dedicated aircraft isstrongly desirable heading into the future. In addition,
since the aircraft is used for various applications at
different altitude, speed and range, deployment will be
required of multiple aircraft with differing flight
performances. To construct a system such as this,transnational cooperation, with multiple countries in
Europe and North America that possess abundant
experience in airborne observation, will be essential. An
aircraft network will play an important role in covering awide area of the polar region. Additionally, since theArctic region is a remote area from Japan, the use of
aircraft will require operating bases in the Arctic region or
nearby.
The use of unmanned drones in the Arctic region is also
regarded as an effective measure. Unmanned drones are
extremely useful from a safety point of view owing to theincreased danger of the formation of ice from supercooled
water droplets while flying through clouds during aerial
observations targeting mixed cloud formations
characteristic of the polar regions. Unmanned drones havecome to be used widely in atmospheric observations inrecent years, and with Japan's accumulating technicalknow-how, we look forward to further advancement inthis field.

Airborne observation is an extremely effective meansof observation across a wide area of Earth sciences.
Remote sensing observation is an essential means ofobservation for the atmospheric sciences as well as in thefields researching vegetation, ice thickness, gravity fields
and topography, in particular.
In the atmospheric sciences, ground-based observation
is observation from a fixed point, and in contrast tohorizontally-confined ship-bound observation, aircraft
can make observations in the three spatial dimensions,thus advantaging aerial observation for three-dimensional
detailed observations of atmospheric structure. Aerial
observation is primarily performed by fixed-wing aircraft,however, rotary-wing aircraft, namely helicopters, canalso carry out aerial observation. But, helicopters pose theproblem of interfering with the atmospheric region thatthey are tasked to observe, so they are often limited toremote observation. Broadly considering aircraft,
observation can also be effectively carried out using
airships, free balloons and tethered balloons -each being
deployed according to purpose. The use of gliders(unpowered aircraft) has also been promoted in recent
years.
The latest in equipment is also required for researchusing aircraft-based observation. In terms of atmosphericobservation equipment, the development of direct
measurement equipment and sampling techniques fortrace gases, aerosols and cloud particles, as well as thedevelopment and equipping of remote measurement
instruments centered on radar and lidar are most desirable,
and the outfitting of drop sonde systems capable ofspatially-dense atmospheric observation is also important.
In all of these cases, it is a continually-important task tomake this equipment as compact, light-weight and energyefficient as possible.
As for sea ice observation equipments, measurement
using a towed electromagnetic induction ice thickness
meter (EM-Bird) is expected for ice thickness
measurement surface roughness measurement. These
instruments can be boarded on rotary-wing and fixedwing aircraft. The Alfred Wegener Institute, Helmholtz
Centre for Polar and Marine Research possesses two longdistance Basler Turbo BT-67 aircraft -the Polar 5 andPolar 6-. They operate for wide-range observations using
EM-Bird boarded on the two aircrafts in the Arctic Ocean
during the spring.
The internal three-dimensional structure and bedrock
topography of ice sheets can provide valuable information
to investigating the mechanism of ice sheet dynamics.
Since the radio-echo sounding using ice radar cannot be
carried out by satellite remote sensing, it must be
performed by the instrument boarded on an aircraft.

154

Oversea Bases for Research / Observationa. Introduction
The Arctic region is a complex environment which
comprises elements that react rapidly to the climate (forexample, vegetation, sea ice and glaciers) and elementsthat react slower to the climate (for example, permafrost
and ice sheets). Understanding the Arctic regional
environment requires not only long-term separate
observations of each of these elements, but also process
research to unravel the interacting systems between theseelements along with empirical observation to evaluate
their influences. Additionally, to understand the regionalwide environmental changes, an international cooperative
regime must be built.
These various observational activities are an important
infrastructural component to environmental research in
the Arctic region. To build this infrastructure, the Japanese
research community should be strongly conscientious of
the direction the international community is taking as wellas our role in that, and we must establish, equip andcontinuously maintain them. Additionally, consideringthat Japanese observations almost always take place inother countries, it is crucial to not only respond
appropriately towards international trends, but to have theinterests and intents of these countries in mind whencarrying out our observations.
The Japanese research community has carried out
various kinds of observations in the Arctic region up to
this point, and has, for those purposes, built bases there.
However, the scale of the space and time of the observed
phenomena was various according to the phenomena eachresearchers want to investigate. In the below, we organize
and categorize information on our needed infrastructurefrom the standpoint of the management systems, functions,scales of time and space, and we describe future
developments while we take into consideration the trendsof the internationally-collaborative research of recent
years.

of fields can be carried out at this base, and there isequipment fulfilling certain observational standard.
These sites are effective for satellite or model
calibration and verification. They require long-term
maintenance and management systems that include
the training of personnel.
(b) Reference sites: These are sites that carry out
continuous observation based on set observational
standards for research of a specific field and in
localities (regions) specific for that field of research.
They require long-term maintenance and management
systems.
(2) Research Bases
In addition to the characteristics of the above
Observation Bases, these facilities also have the additional
characteristics which follows.
1 These bases are fora for the training of Japanese and○local personnel, for the mutual sharing of research andfor collaborative analysis.
2 They are located nearby to observation bases and○wide-area observation networks.
(3) Wide-Area Observation
1 Periodic Observation○
This is observation of elements in particular fields ofresearch that is repeatedly carried out in specificregions and at specific times. It primarily refers to
observation over the long term. This not only involves
observation on land, but also involves oceanic
observation along coastlines around the land
observation base.
2 Network Observation○
This is observation that is carried out over the longterm in a given region for a specific field of researchacross multiple bases (generally 10 or more). The
observation takes a variety of forms, with both manual
observation and automatic observation being carriedout successively with instruments. Examples of thisinclude the frozen ground observation network and theglacial seismic observation network.
It is possible that there are many cases where wide-area
observations are carried out from a research or
observation bases. We would also like to point out that
there is an Arctic-wide network such as the International
Arctic Systems for Observing the Atmosphere (IASOA).

b. Categories of Observation / Research Facilities
The bases for research was categorized as either
research bases or observation sites. In addition, we will
also describe the observational functions and observed
phenomena across a wide region.
(1) Observation Sites
These are facilities that carry out collaborative research
regarding observations and they have the following
characteristics.
1 This category of base comprises two (or more)○countries working collaboratively; it is managed basedon an agreement; equipment can be brought in basedon the agreement; samples, observation materials anddata can be secured or brought out.
2 This site has a work space established along with on○site managers and researchers posted; workers stay onsite and cooperate with the research and observations
carried out by Japanese researchers.
Observation sites can be further broken down into thetwo following categories.
(a) Integrated sites: Continuous observations in a varietyc. Management of and Candidates for Observation Bases(1) Candidates for observation sites and research bases
Table 5 indicates the observation site candidates
organized by field of research, categorizes the above sites
and observations, and describes the current observational
status in the remarks section. Moreover, research theme
for each sites and bases is indicated. In figure 65, the area
indicated by a shaded square on the map showing theposition is the candidate area for expansion in the coming
future. Table 6 shows the observed phenomena among
other information organized by field of research. Uponconsidering international trends and the role expected of155

Table 5: Observation sites and Research base (Existing and candidate)

Figure 65: Position of observation sites and research bases.

156

Table 6: Observation items, equipment and infrastructure needed at theobservation sites for variou
s research field.

Nagoya University, among others, have been focusedhere engaged in ground-based observations of vegetation,
frozen soil, greenhouse gases, hydrology, and snow andice since 1990. They have used this base as their starting
point to expand their observations out to the coastline of
the Arctic Ocean and a wider area. They have been
carrying out tower-based observations there since 1997,
with the Netherlands currently being involved. There arealso new researchers participating through the GRENE
Project. This is the initial reference site for the World
Metereological Organization's Global Cryosphere Watch(WMO/GCW), and it has also become a site for
INTERACT. This will also be the base for the multiple
combined-use field stations spreading along the coastlineof the Arctic Ocean, such as at Tiksi.

us on the international stage, we have set out the order ofpriority for outfitting/developing these sites and bases
according to the important projects Japan will pursue.
Among these, the following bases are either locations
that currently come close to fir the condition as researchbases or are locations that we desire to be so.
1 Ny-Ålesund, Svalbard○
This is an international collaborative observation area
hosted by the Norwegian Polar Institute with numerous
participating countries, and the National Institute ofPolar Research has had a station established here since1991. Research in numerous fields has been conducted
here; however, currently there is monitoring ofgreenhouse gases, observation of clouds and aerosols,
snow and ice sampling, long-term observation of thetundra ecosystem, fixed observation of circumpolar
atmospheric cycles, and upper atmospheric observation.
This base functions as a collaborative international base,and to maintain and develop it, we must increase ourpresence to meet Japan's obligations there. There areplans to also strengthen the international collaborative
research there through the Svalbard Integrated Arctic
Earth Observing System (SIOS), and the fullfunctionality of Japan's station will be an importantpresence in this.

3 Fairbanks, Alaska○
JAXA and JAMSTEC have been engaged incollaborative research at this base with the International
Arctic Research Center (IARC) at the University of
Alaska Fairbanks since 1997. Currently, the involvementof both of these Japanese institutions is waning; however,this base can be characterized as an observation site anda research base with numerous achievements in training
personnel, including in periodic wide-area observation,and should continue to be maintained as a research baseinto the future.
Among other bases that can be expected to be used in
the future are the Canadian High Arctic Research Station(CHARS) in Cambridge Bay, Nunavat, and the Baranova
base in Severnaya Zemiya, Russia. These bases are not

2 Yakutsk, Eastern Siberia○
The Japan Agency for Marine-Earth Science andTechnology (JAMSTEC), Hokkaido University, and

157

The following points of caution must be observed inmanaging research and observation bases.
1) With respect to the efficiency of research and theconvenience of the base occupants, it is ideal for asingle organization to be charged with themaintenance and management of a base.
2) Since long-term observations are important, a stable
management funding system covered not bycompetitive funding, but through a grant system froma designated institution is desirable.
3) There must be observation standards put in place foreach field at observation sites, and data must be
refined.
4) A mechanism should be introduced to allow for thesmoother transition of new researchers.

only useful for observations of the atmosphere, tundra,snow and ice, but they are also highly accessible tomarine observation.
(2) Management of Observation Bases
Among the research and observation bases, the basic
areas of the long-term, large-scale bases are handled by
the appropriate domestic core institutions, and it is best foreach project to handle its own share of everything else.
Additionally, should there be land observation sites ofother countries or the host country in close proximity to
the base, there must also be the notion of a 'designatedobservation zone' at the international level for a certain
area centered on the research bases and observation sites
in which Japan is involved.

Archive System for Data and Samplesof the time limit of a research project, and for the archive
to be maintained, as a principle, by a permanent research
institution, and not a short-term project with a specificlife-span.

a. Background
There are various changes occurring in the Arctic
region due to global warming. Research up to now hasrevealed a reduction in the sea ice of the Arctic Ocean, an
increase in ground temperatures in Siberia, melting of thepermafrost, an increase in arctic river discharge, and areduction in the amount of snow cover area, among otherchanges. Additionally, there are concerns about the effectthat such changes may have on ecosystems and humanactivities. Among the environmental changes in the Arctic
region and the mechanisms that drive them there are still
numerous areas that have yet to be explained, and theactual conditions and mechanisms need to be explained.
Research efforts up to now have pursued their own
separate fields for the atmosphere, ocean and land;
however, the Arctic region is a system comprising theatmosphere, the ocean, the land and the snow and ice, andeach system therein includes its own phenomena thatdiffer along scales of time and space. To elucidate thechanges along these different scales of time and space aswell as the complexly-integrated changes in different
fields making up the environmental changes in the Arctic
region, there must be a new understanding of processes
and explanation of mechanisms that use integrated data
sets with accumulated observational data and research
results that span multiple fields. The establishment of anarchive system for data and samples is a importantresearch infrastructural component that is neglected inalmost all research projects, and is of conceivably greatpriority. Retaining all digital data and samples in common,
establishing an archive system and managing the data,
promoting the sharing of data among researchers andhaving a system that links to new research will likely leadto research with increased potential.

(2) Data Archive Accessibility
A data archive system must be as user-friendly as
possible for both the data provider and the data user. A
data archive system exists to not just have data input into
it, but also to be widely used by researchers, and ease ofaccess to browse data by users is essential. Setting up a
search service and a data quick-look tool can likely becalled the lifelines of an archive system. For example,
with the Arctic Data archive System (ADS) that isundergoing trials at the National Institute of Polar
Research, we believe the development of a datasaving/search function and a data-browsing system thatallows minimal analysis is important, and thatdevelopment of these must be continued into the future.
From the data providers perspective, there is a strong
need to reduce the burden of and ease the access to registerdata. Enhancement of metadata to the contrary parts at thispoint, but an environment must be established that allows
for the smooth registration of data through theconstruction of a support structure from the perspective ofthe data archive system.
(3) Data Flexibility
Arctic environmental sciences is a broad academic field,
and data formats naturally have wide-scope. Humanities
and social science data have also grown in importance inthe realm of environmental research in recent years, and asystem that goes beyond the current digital data formats
and can handle a multiplicity of data formats is desirable.
Additionally, there has been increased acquisition of highresolution temporal and spatial data, and data volume forobservation data and model output has grown extremely
large in comparison with the past. Handling this kind ofcomplex, multifarious and voluminous data would require
a considerable amount of effort by a general researcher,
and would not be regarded as useful. A data archive
system should be constructed in the future that can both
handle complex, multifarious and voluminous amounts ofdata, and be convenient.

b. Data Archive
In the following we provide suggestions for a Japanesedata archive that we regard as important based on thecurrent situation.
(1) Data Archive Stability
Data archiving, it is a stable system are conditions
required minimum. Here by 'stability' is not only
redundancy archiving (having back ups), but an archivethat can be maintained for the long term. It is particularly
important for a data archive to have reliability regardless158

is less of a need to collect and accumulate observational
data in international data centers. However, there is noemphasis placed on the data management duties toconstruct and release data sets for field observations madeby Japanese domestic research institutes anduniversities;.They rely on the data centers of othercountries. Yet, the data that has been acquired throughresearch observations carried out by national funding are
precious, and must be released by Japanese institutions
and be made more accessible for Japanese researchers.
There are barriers for the research institutes anduniversities to carry out this for the field observation databy themselves, and there is a need for Japan to have its
own integrated data center and release data in the field ofArctic region environmental research. Additionally, forthe above data to be published and disseminated andinternational
coordinationtoadvance
Arcticenvironmental research, Japan must carry out these efforts
in an integrated manner, and should introduce a data
center function.

(4) Promoting Data Rescue
The Arctic region is behind the rest of the world in data
maintenance, and data that are not disseminated globallymust be collected and managed. Further, data rescue (thedigitizing and saving of data that have been written downin paper form and are in danger of being lost forever if notstored appropriately) must be urgently done in this region.
(5) The Publication and Distribution of Data
The assignment of digital object identifiers (DOI) fordata sets to guarantee permanent data set links has been
advancing in the past several years at data centers. A DOI
is a character string to identify digitized contents and arenecessary components to improving the distribution andutility of data, as well as in guaranteeing the permanencyof links. In Japan, they are currently used only foracademic papers and books. Japan must assign DOIs todata that we have acquired ourselves and we must promote
the distribution of this data.
Many academic journals that aim to list and publish
data are put out by major publishing companies. Some ofthe primary examples include Earth System Science Data
(EGU), Geoscience Data Journal (Wiley) and ScientificData (Nature). These media are not only effective forpromoting the publication of observation data, but also forundertaking data rescue. There should be serious
consideration made in regards to the publication of data
journals domestically or the establishing of similar media
through the expansion of existing journals.

c. Archive System for Samples
Arctic environmental research includes a lot of sample
acquisition and analysis-based research, and a mechanism
for the long-term and stable archiving of samples is
extremely important. In consideration of the fact thatsamples obtained during research have been and willcontinue to be valuable assets, and that there is a need topass these samples down to allow successive and longterm research, we believe it would be advisable toestablish an institution, independent of the institutions towhich researchers belong, that can maintain a sample
storage and distribution system to allow for new analysis.
In the above case, there is a possibility that it would benecessary to devise a system where, if possible, the sample
is divided and part of it is managed by an institution, suchas a science museum, and the other part is managed by the
researcher who obtained the sample. It goes without
saying that this independent institution or science museum
will require stable funding and staffing, and for not merely
10 years, but with a long-term perspective in mind.
What will be simultaneously important is the metadata
for the sample. To inform researchers of samples and topromote analysis and research, sample metadata must be
created, and sufficient information should be released andaccess made easier to samples that have or will be taken.
The archive sample systems required differ largely bysample type and properties; but, there is adequate
flexibility in data format for metadata that the collection
and release by the aforementioned data system is possible.
We believe that serious consideration should also be given
to the role of the data center as a collector and manager ofsample information (and not just numerical observationdata).

(6) International Coordination
There are various regions and countries in the Arctic
region, and international coordination in the usage of data
is a must to understand the Arctic environment. A database on Arctic research is operated by a number ofcountries, primarily focused on the Arctic countries, andvarious data centers and data portals exist (NSIDC,
CADIS, GCMD, GEO-Portal, GCW etc.). It is notrealistic to integrate these into one system. However, it isextremely important to coordinate these systems; afunction should be introduced that enables mutual use of
metadata and searches from other databases and a
distributed database should be built through international
coordination. Data management has currently just begun
to be discussed by the Data Management Working Groupof the International Arctic Science Committee and theSustainable Arctic Observation Network (SAON), andinternational coordination must be actively advanced
going into the future.
(7) The Necessity of an Arctic Data Center
Data sets are managed by the accompanying metadata.
As IT advances and information sharing expands, there isa tendency to integrate the format of metadata, and there

Personnel Training
cannot find indeterminate research positions, and manytake post-doctoral positions, the number of students who
aim to enter PhD programs has decreased dramatically.
We aim to suggest measures to overcome this state ofaffairs. We will train talent to fit a variety of paths, and tie

a. The Current Status of Personnel Training in Japan
for Arctic Environmental Research
Japan has fundamental problems in personnel training
in general, and not just limited to Arctic environmental
research. Owing to the fact that many PhD graduates
159

The entire spectrum of Arctic-oriented research affiliates
in Japan must use JCAR as a mediator with thesecoordinating networks to promote these efforts so that
more effective personnel training is carried out.
(1) The Training of Researchers
The following programs will be carried out throughcoordination among universities in Japan andcoordination between Japanese universities and theuniversities of the Arctic countries.
- An internship program will be established that allows
for the participation of graduate and undergraduate
students in research activities.
- Carry out a summer school, and administer education
as a community for undergraduates and graduates who
have started research.
- Choices for career paths will be increased after earning
Ph.D, by development, introduction and training
offered for post-graduates.
- A job-seeker bank will be created, and PIs and students
will be matched beyond the limits of just universities
and acquaintances.
- Support activities for young GRENE researchers
dispatched to the field, and a dispatch system that aims
for research at foreign research institutes anduniversities shall be established as a follow-up effort.
- Establish a support system to assist fieldwork in the
Arctic region.

this training to industry, which will use it as fuel for
growth. There is also a need to train not just experts in thenatural sciences, but also in the humanities and social
sciences, and to develop education plans that particularly
allow for an integrated approach between the two. It isalso important to cultivate knowledge on Arctic societies
affected by environmental changes. Since Japan does notpossess any territories in the Arctic, we must conduct
observations and field research outside of the country to
carry out on-site observations and field surveys for Arctic
environmental research. As many Japanese undergraduate
and graduate students do not opt to go overseas, the Arctic
seems like a far place; however, we propose measures toreduce the barriers for them.
b. International Efforts to Train Personnel
The following three organizations are engaged ininternational cooperation on Arctic environmental
research.
(1) APECS (Association of Polar Early Career Scientists)
This is an organization run by students and young
researchers carrying out research on both polar regions;
i.e., it is supported by funding from numerousorganizations, such as IASC and SCAR, and it engages invarious activities. Becoming involved in APECS andparticipating in activities is effective to building careers
for youth aspiring to be researchers. JCAR has supported
the start-up of a Japanese domestic offshoot organizationof APECS, and has begun the preparations to do so.
Support in the form of funding activities for APECS andthe domestic offshoot organization should be carried out
in the future.

(2) International Coordination
Exchange activities will be smoothly promoted throughnot only the cooperation of JCAR in the activities of
APECS, but also the strengthening of ties of Japanese
universities with the University of the Arctic, UNIS andother universities in Arctic countries. We also believe thatuse of the IARC is effective. The safety of students who
are dispatched and stay at IARC is paramount, and the
IARC has a system in place to ensure this. Additionally,
English is the common language, so communication iscomparatively easy.
The actions taken by ARCUS to train personnel would
likely be a good reference for future efforts. For example,
TREC is an initiative for school teachers to experience thefield and the research involved there. If this can be carriedout in Japan, it would be an effective means ofdisseminating research activities.
One international effort that Japan should give priority
to promoting is contributing to the training of personnel
by setting up an invitation system targeting young
indigenous researchers. The results of this will also be
fruitful for international coordination to provide overseas
training for young Japanese researchers. Further, byinviting young researchers from non-Arctic countries,
particularly in East Asia, this builds a foundation fortransnational coordination and international collaborative
research over the long term.

(2) University of the Arctic
The University of the Arctic is a university network
comprising over 130 universities with member schools
being primarily from the Arctic countries, along withassociate member schools. The University of the Arctic
offers numerous courses (lectures and seminars). In 2011,
Hokkaido University was registered as an associate
member school, and began activities in partnership withschools like the University of Alaska.
(3) The University Centre in Svalbard (UNIS)The University is located at Longyearbyen on the
Svalbard Archipelago, and the National Institute of Polar
Research has an office there. It is the world's northernmost
university, and it was established in 1993 by a federationof universities in Norway. There are nearly 20 faculty
members, and students there can experience fieldwork.
Almost 300 students from around the world select courses
there each year, while there are only several students fromJapan.
c. Future Issues to Consider for Training Personnel
We propose that instruction and general literacy ofspecialized knowledge be firmly established in addition toa support regime aimed at training researchers. The efforts
we expound on below must not just be carried out by
individual researchers and research institutions alone, butmust be promoted through coordination among domestic
universities along with coordination between Japanese
universities and the universities of the Arctic countries.

(3) The Succession and Development of Specialist
Technical Knowledge
There have been reductions in technicians in research
institutions, including universities, through administrative
orders for the efficient placement of personnel. Yet,technological innovation plays a major role in supporting
the development of cutting-edge research, and there is a160

need in Arctic environmental research for both hightechnological capacity and new developments inmodelling, observation techniques, satellite data analysis,
chemical analysis, and DNA analysis, among others. We
must secure the infrastructure to improve technologies
like the further development and sophistication ofpredictive models, the precise analysis of parameters, thesophistication of ship-bound observation, and thediversification of observation parameters. The most basic
condition for the succession and development of technicalexpertise is the cultivation and employment of technicians.
Additionally, to reduce the barriers between technicians
and researchers, it is likely effective to propose various
axes of evaluation.
The information exchange among different fields ofresearch cannot keep pace with the rapid development oftechnology, and some fields cannot make use of theincredible technology available. Coordination acrossvarious fields of research will be helpful in allowing for
the quick exchange of information. Even withcoordination among specialists who use different researchtechniques, such as with coordination between on-site
observation specialists and modelling specialists, it is thetraining of researchers and technicians who can link up
with each other that we must devote our efforts.

(4) Establishing Literacy and Conducting Outreach
There has always been emphasis placed on theimportance of the Earth's environment in the sciencecurriculum of elementary and junior high schools. The
average citizen's ability of comprehension is thefoundation for the dissemination of knowledge, and there
is reason to require JCAR members who are affiliated withelementary and junior high education. By sharing
knowledge and information with members associated withschool education, the importance and appeal of Arctic
environmental research can be accurately and efficiently
communicated to younger generations. We should also put
our best efforts into activities, such as public lectures andscience cafes, that communicate the appeal of cuttingedge research to elementary, junior high and high school
students. Public outreach activities will be linked to thetraining of personnel to communicate the importance ofArctic environmental research, and will increase thenumber of students interested in the field. The Arctic
region is a far place in the minds of the students, but it hascities and towns where people live, and it is possible todevelop programs for the students to experience the region.
By providing opportunities for this kind of experience,
students will gain an education by experiencing activities
in the field.

Promotional System for Research
as well as international organizations that take a partial
interest in the Arctic region, such as the World Climate
Research Programme (WCRP) and the Global Earth
Observation System of Systems (GEOSS). Since researchin Japan is placed in circumstances where it cannot
possibly survive being unaffiliated with these groups, thismeans that Japan must becoming strongly involved in theactivities of international organizations, by offering the
input of the Japanese perspective into and cooperation
towards the policies of these international organizations.
Further, as part of this, there are numerous requests forbilateral cooperation received, and the opportunities toadapt to these frameworks and evaluate theimplementation of research through them are on the rise.
There are also international frameworks regarding
funding that are beginning to appear, such as the Belmont
Forum, and the climate for promoting research is growing
in complexity.
We must devise a Japanese domestic system to rapidly
and suitably accommodate these international trends as agroup.

a. Background and Objectives for Setting Up thisPromotional System
Arctic environmental research is growing in complexity
and size, and it is important to construct a system thatallows it to be carried out smoothly, efficiently andproductively. To these ends, there must be a systemestablished that can promote research inside Japan.
The complexification process refers to the spread of thesocial fields required of scientific knowledge to not only
the scientific community, but to industry and resources as
well; it also refers to the invigoration of policy by thevarious government organs that relate to this; and, it is also
the rise of indispensable international frameworks. These
are international trends seen in numerous countries, andthe effects of these trends have also been felt in Japan tothe extent that they are altering our system here. This kindof situation regarding the Arctic region differs from thesituation of the Antarctic region, and these complexifying
conditions require research to be promoted efficiently andeffectively. This implies that relations outside of thedomestic community are strongly needed, even in cases of
pursuing scientific truth, and this is a new chance for us.
However, to carry this out in a smooth manner, we need toreview our system of research.

c. Envisioning a Japanese Domestic Promotional
System for Research
In terms of a domestic system, the following basics
must be given due consideration and design must be
implemented based on them.
・ Researchers can implement new research based on
unencumbered and novel ideas on the basis of acommon infrastructure arranged for them as theyrequire it. To these ends, a system must be erected toallow for the common use of as much research
infrastructure as is possible.
・ Japanese researchers and institutions will smoothlyb. International Trends
Research on the Arctic environment must be promoted
through the cooperation of both Arctic and non-Arctic
countries. There are international organizations that exist
to determine or advise on the direction of research andactivities in the polar region, like the International Arctic
Science Committee (IASC) at the center as a union ofscientists, the Arctic Council (AC), comprising mainly thegovernments of Arctic countries, and other related groups,
161

Japanese domestic Arctic research must be madeavailable and maintained in a place where it can beeasily accessed by both the general public andexperts (perhaps on a Web site).
(6) It has been three years since the Japan Consortium
for Arctic Environmental Research (JCAR) wasestablished, and JCAR has fulfilled an important rolein the promotion of Arctic environmental research. It
has been a short period, but considering the status of
the core institution and the primary organs, and thesituation surrounding the promotion of research atboth the domestic and international levels, there must
be an examination of the future roles and existenceof those bodies with a long-term perspective in mind.

carry out their research, and Japan can execute ourinternational duties as a whole, amidst theinternational framework and its constraints.
・ Japan will be able to facilitate an interchange
between disparate societal levels and fields ofresearch domestically, and return results in their
entirety to society at large.
d. System Specifics
Strengthening of the following system specifics isdesired.
(1) We aim to strengthen the core institution which willlead the effort to advance the system of domestic
promotion and implementation of research. It would
be ideal to have a Promotion Committee, comprising
primary organs and related groups, established in thecore institution that serves the function of promoting
general research, cooperation with funding
institutions and the setting up of infrastructure. The
core institution called for the establishment of an'Arctic Environmental System Research Base' in a
“Large Research Project” proposal in 2013 to the
Science Council of Japan; such a proposal would be
welcome.
(2) The arrangement of the research infrastructure(observation platforms, overseas bases, equipment,
models, data) shall be handled by the primary organ,
and infrastructure shall be allotted to institutions tobe provided to researchers and research groups. To
accomplish this, we should envision the setting up of
a new organization. In arranging for observation
platforms, some equipment and models must be
considered in view of the entire condition of global
science research.
(3) Role-sharing must be determined to promote eachfield of research domestically and research mademore efficient based on the requirements forinfrastructure. Considering the current status of
global science research promotion in Japan, it isappropriate to have separate institutions handling thepromotion of marine research that uses ships to
conduct research and land-based snow and ice
research carried out primarily on the land of othercountries. The primary institutions handling otherfields of research must be made clear to an extent forthem to promote their research. Also, while satellite
observation is a crucial means of conducting research,
improvements must be made to the Japanese
domestic data-use system, as there are numerous
problematic issues associated with its use by
researchers.
(4) The environmental changes of the Arctic region are
occurring as a result of interacting factors, and it isimportant to treat them as a system. It is, therefore,
necessary to consider a system that can allow for thearrival at an accurate understanding of these
phenomena through academic research thatcomprises frequently-exchanged knowledge acrossdiffering fields.
(5) Since environmental changes in the Arctic region
will have major societal effects, a system must be
established that promotes the spread and theimprovement of scientific knowledge in society.

e. Preparation / Development / Maintenance of
Research Infrastructure
We have so far described the necessity and developmentof the infrastructure, including equipment; however, theseremain behind schedule for the Arctic region. The Arctic
region is similar to Antarctica in that it is a cold region;
however, it largely differs from Antarctica in that the
Arctic Ocean is surrounded by land on its peripheries, thatland is expansive, and there are various restrictions thatcome with that land because it is the territory of specificcountries.
Numerous suggestions have been put forward so far,but, the need for funding is obvious, and priorities for it
must be assigned, development must occur along thosepriorities and it must be put to practical use. Also, it must
be studied whether it is appropriate to develop thisourselves from the standpoint of efficiency, or if weshould obtain something similar to that being used
overseas and rapidly apply it to observations.
The case of the data archive, one facet of the research
infrastructure, is an international issue; from theperspective of going past Japan and making global
research more efficient, it is a field that we must promptly
act on, and a system is needed now more than ever.
f. The Promotion of International Cooperation
We have described previously how, in the realm ofArctic environmental research, international cooperation,and for that reason, the push for internationalization ofJapanese researchers and the researcher environment has
grown in importance over the past. However, theaforementioned core institution, related organs andgovernment bodies must be aware of the following points.
(1) Secure preparation and distribution of information
regarding international institutions, foreign countries
and projects: Secure suitable information through the
distribution of information in Japanese and theformation of specialist groups.
(2) Establish a consultation function, and specificallyand individually support international researchplanning.
(3) Prepare accords and cooperative methods forJapanese researchers with highly-similar foreigncountries.
(4) Promote cooperative activities at high levels (binational science and technology accords, AC, IASC).
(5) Promote efforts regarding the internationalization ofresearchers and the research environment.
162

Belmont Forum, is effective, and that including
continuous observations of natural phenomena in the
Arctic region, and not only the 'Natural and Social
Themes' presented at the 2014 stage, is an important
forum for promoting international cooperation.

-Support the participation of researchers at theearliest stages in planning conferences and such.
-Dispatch office and research personnel to offices ininternational organizations and projects.
(6) We believe that international funding, such as the

Research Equipment by Fieldof cloud and aerosol particulates, and many of these
instruments have been improved for use in ground-based
observations and are effective for long-term continuous
observations on the ground.
Precise radiation observations will be the foundation forresearch into the climatological effects of atmosphericcontent, such as greenhouse gases, clouds, aerosols andwater vapor. BSRN is being developed as a global
network of radiation observation. The measurement
standards determined by BSRN are positioned as theworld standards of radiation measurement, and making
these the standards for radiation observation in the Arctic
region is desirable. However, owing to the difficult
environmental
conditions,notonlyradiationmeasurement, but also atmospheric observations in the
Arctic region will require significant effort to maintain themeasurement instruments on site to retain their precision.
The observation sites that monitor water, energy andCO2 exchange between the atmosphere and the land
surface must be increased. Construction has been
undertaken on an observation network known as
FLUXNET , and the density of observations in the polar
regions is extremely low (as of April 2013, in contrast to
the 40 sites between Japan and Korea, there are a total of
3 for Siberia) in comparison to Asia (Asiaflux), the US(Ameriflux), and Europe (Euroflux). Observation datafrom flux towers can, apart from monitoring a site, be usedas the lower boundary conditions for climate models.
Further, in recent years, attempts have been made to merge
the data with climate models through data assimilation
techniques. It will likely become increasingly important in
the future to have an increase in the observation spatial
density of flux towers so that the water, energy and carbon
cycles can be understood between the lower atmosphereand the land surface in the polar regions. Observation data
in a plot scale is applicable as a validation data for satellite
observations (known as “ground truth”). The few Arctic
observation sites will serve an important role as groundbased verification sites.
Observation data of the meteorological conditions
necessary to drive many land surface models, such as
surface air temperature, precipitation and wind speed, arecollected and maintained by research institutions both
inside and outside Japan (for example, there is theBaseline Meteorological Data in Siberia through
JAMSTEC). We must continue site observations tomonitor the signals of the polar regions, which will likely
display more serious impacts of warming in the future.
Regular maintenance of instruments is essential for highquality observations. Inspections and maintenance tocheck if there are any contaminants in rain gauges, or if
the surrounding environment is appropriate to theobservations, are necessary once every half year.
There must be technological development to improve
the trap efficiency of rain gauges to observe precipitation.

a. AtmosphereAn atmospheric observation strategy in the Arctic
region will likely take the form of long-term continuous
observation infrastructure that comprises the organizationof a ground-based observation system, wide-area
observation using satellites, ship-based ocean observation,and three-dimensional structurally-detailed observations
by aircraft. Moreover, these observations complement
each other, and would ideally take the form ofcomprehensive observations integrating all methods.
The instruments used in atmospheric observation can be
broken down into the categories of remote sensing and insitu measurement. Remote sensing is generally
measurements that use electromagnetic waves (primarily
in the range of ultraviolet to microwave). There are twocategories of sensors—passive sensors, which receive(detect) one-way electromagnetic waves from the object
being observed; and, active sensors, which transmit
electromagnetic waves and then receive (detect) thereflected energy from the object being observed.
Additionally, in situ measurements are not just limited toon-site measurements using measuring probes oranalyzers, there are times when a sample is taken at thesite and brought back to the laboratory for analysis. The
most appropriate methods can be selected from thesevarious methods according to the object being observed or
the purpose of the observation.
Thinking in terms of a ground-based observation
system that observes meteorological phenomena such as
clouds, aerosols, trace gases, atmospheric components,
such as rainfall or snow, temperature, humidity and wind,then a system is needed that combines active and passive
remote sensing as well as in situ measurements. Radar,which uses radio wave frequencies, and lidar, which uses
visible-range laser light, have been often employed as
active sensors; and, multi-wavelength, Doppler volumescanning instruments are extremely useful for measuringphysical volumes and knowing volumetric changes tohigh precision. Simultaneous measurement using Doppler
cloud radar and multi-wavelength polarized lidar havebeen indispensable tools for research into cloud
microphysical radiating. For passive sensors, instruments(spectroradiometers for microwave, visible light, andinfrared bands) are needed that can measure a highresolution wider spectral band to more accurately quantify
physical volumes through remote sensing.
In the continuous observations of CO2 and othergreenhouse gases of recent years, CRD spectroscopy has
become widely used as a new technology for the accurate
detection of trace gases. This method has also been
applied to direct measurements of the absorption
properties of aerosols, and its use will likely become quite
popular in the field of atmospheric chemistry.
There have been significant advances in thedevelopment of probes for use in direct aerial observations
163

Figure 66: (Top) Current EISCAT radar system and(left) schematic image of EISCAT_3D radar system(http://eiscat.nipr.ac.jp/eiscat3d/)

cooperation in Northern Europe to monitor the geospaceenvironments: e.g., the lower, middle and upper
atmosphere, as well as the ionosphere. The EISCAT radar
has monitored the geospace environments over 30 years
up to now. As the next step, a large-scale overhaul plan
(EISCAT_3D Project) is being advanced. Japan is also
participating in this Project which involves the monitoringand 3D observations of changes in the atmosphere andionosphere (at altitudes of 1-30 km and 60-1000 km). By
building and maintaining a radar network with Japan's
own large atmospheric MU radar (Shigaraki, Japan), theEquatorial Atmosphere Radar (Indonesia), and theIn the polar regions, snow is frequently observed as
precipitation, and a large portion of falling snow does notenter the rain gauge due to wind. The rain gauge ought tobe improved and a statistical method developed forcorrecting the observed value to accurately understand theamount of rainfall and snowfall.
b. Middle and Upper Atmosphere(1) European Incoherent Scatter Radar (EISCAT
Radar)
A large radar system (EISCAT radar) has been
established and is managed through international

Figure 67: (Left) The ERG (Exploration of energization and Radiation in Geospace) satellite(http://www.jaxa.jp/projects/sat/erg/index_j.html) and (right) airglow observation with IMAP/VISI on theinternational space station (http://www.iss-imap.org/)164

system. The integrated observations with them will enable
us to understand effects of energy and momentum
injections from the lower atmosphere and space onchanges in the middle and upper atmosphere.
(5) Data Analysis, Modelling and Simulations
It is crucial to link the aforementioned satellite-based andground-based observations with modeling and simulation
studies. We should continuously develop new techniques
for modeling, simulation, and data analysis: e.g.,modeling of complex chemical and physical processes anddeveloping methods of high performance computing. In
order to handle vast amounts of data, research
environments such as hardware and software systems
should be also updated continuously.

PANSY radar (Syowa Station, Antarctica) and the
ESCAT_3D radar systems, we will have an exceptionally
powerful infrastructure for the Earth’s environmental
research.
(2) Satellite/Rocket/Balloon-based Observations andDevelopment of On-board Instruments
By launching the magnetosphere observation satellite
ERG in 2015, we can monitor details of the geospaceenvironments around the Earth, such as high-energy
particles and the propagation of plasma waves. Somegeospace explorations have been also planned by various
countries: e.g., the Van Allen Probes (US: launched in2012), which explores the inner magnetosphere,
Resonance (Russia: 2016 launch), VSX (US: 2016
launch), Swarm (Europe: 2013 launch), which observes
the ionosphere. Additionally, some imaging observations
from the International Space Station (ISS_KIBO module)
are made to monitor atmospheric changes in the vicinityof the altitudes of 100 km and 250 km. Observations of
the same sort must be continued in the future, and, as thenext step, simultaneous, multiple observations must be
realized by multiple satellites. Through developments ofsatellite-borne instruments in the Japanese science society
with the newest technology, such as photometers,
accelerometers, mass spectrometers, particle counters andplasma measuring instruments, a variety of satellite
missions will be possible. Rocket/balloon observations
are indispensable in areas where satellites cannot go (fromthe stratosphere to the lower thermosphere). Rocket
experiments in conjunction with the ground-based andsatellite-based
observations
withinternational
collaborations must be carried out (for example,
collaborative observations with Norway have provenfruitful for many years).

c. Snow and Ice
It is extremely important to conduct in situ observations
and samples collections in Arctic cryospheric research.
They are not only important for elucidating thefluctuations and mechanisms of changes in thecryospheric environment at the observed sites, but theyalso play a large role in providing input and verification
data for numerical models and calibration of satellite data
for wide-area monitoring. Therefore, their long-term
continuations are essential. There are physical properties
and samples in the interior and bottom of glaciers that can
only be obtained on site.
(1) Observation of Ice Sheets and Glaciers
There must be long-use observation sites in place toobserve ice sheet and glacier mass balances and toevaluate the effects of biological activity on snow and ice.
Specifically required are research facilities to act as thebase for observations, means of transportation required forfield observations, such as snowmobiles and small
watercraft, and observation equipment, such as automaticweather surveying instruments and GPS receivers. Ice
core drilling and ice sheet radar observations must be able
to be flexible enough to be performed in a wide area, andnot limited to a fixed observation site. The instruments
needed for this are ice radar and laser altimeters used on
airplanes and helicopters, hot water drilling system and ice
core drilling equipment for use with observations andsampling the interior of ice sheets, and boreholemeasurement devices. It is crucial to newly develop or
overhaul existing equipment. Seismometers andseismological observation systems are required formonitoring seismological activities in glaciers. The
representative instruments of these are shown in Figure 69.
Additionally, to carry out in situ observations tounderstand the formation process of proxies forenvironmental changes (see Theme 6), a portable analyzer
for water vapor isotopes and aerosol density is essential.
It is also important to construct and maintain a system(personnel and organization) to be able to carry out
continuous development of instrumentation, on-site
observations and sample collections.

(3) Installation and Maintenance of Instruments for
Wide-Area Multipoint Observations
To understand features and roles of the atmosphericgravity waves and planetary waves in the middle andupper atmosphere in the Arctic region, MF/meteor radar,which measures wind speed and temperature at altitudesof 70-100 km, lidar, and airglow observations arenecessary in the wide area in the Arctic region.
Additionally, to understand the fluctuations in theionosphere and the acceleration and heating processes ofhigh-energy particles near the Earth, GNSS/GPS receivers,
airglow/aurora cameras, and VLF/ELF/ULF wave
receivers must be developed and deployed widely in thearea surrounding the Arctic. This observation network
will have contributions to obtaining a general picture of
the longitudinal generation/propagation/dissipation of
atmospheric waves and the longitudinal motion of highenergy plasmas around the Earth. Establishments ofinternational and domestic collaboration regimes arenecessary for building up and maintenance of the above
mentioned observation system.

(2) Ice Core Analysis
To reconstruct the fluctuations of past climate andcryosphere, laboratory analyses of ice core samples areneeded. Targets for the analyses include water isotopes,(4) Installation and Maintenance of Instruments for
Integrated Observations at Specific Sites
It is also important to set up instruments mentioned
above at specific observation sites with large and highperformance instruments such as the EISCAT radar
165

Figure 68: Instruments constituting Arctic Observation Network

drilling must be done in multiple spots, there must also be
development of a highly-mobile permafrost drillingsystem of a size that can be operated by a researcher aswell as a sample collecting system from a ship that does
not disturb the permafrost that exists on the seafloor andthe bed of lakes. To understand the permafrost ice-melting
process and to reconstruct the ancient climate from thepermafrost temperature, the required equipment
development includes a ground temperature sensor with
precision up to two decimal places, to heighten the
precision of temperature measurement near the melting
point, a logging system, and observation technology toperform on-site measurements of the amount of
nonfreezing water. In addition, improvement is needed on
the measuring instrument for thermal parameters applied
to the ice lenses, organic distribution and structure of soilin the active layer.

aerosols, solid particles and gas composition, and it isnecessary to establish and maintain measurement devices,
analytical techniques and analytical systems in order to
conduct high resolution analyses. In addition to theexisting analytical devices (mass spectrometer, liquid
chromatograph, gas chromatograph, particle analyzer,
black carbon analyzer, etc.), new instruments are required
to enable estimation of origin and transport routes of gases(greenhouse gases, noble gases, etc.) and aerosols (sulphur,calcium, strontium, lead, etc.) through high-precisionisotopic analyses, as well as quantitative estimations
through combinations of multiple proxies. A continuous
melting technique has become operational to obtain alarge amount of high-resolution environmental data fromice cores; however, it only has a short history of usage,
and thus its further development is crucial. Innovations
must also continue on analytical techniques that are usedin combination with a continuous melting device, such as
laser absorption or scattering applied for snow and ice
sample analyses and air extraction.

(4) Measuring Precipitation and Snow Accumulation
The most important aspect of measuring precipitationin the Arctic region is the highly-precise measurement of
winter-time precipitation amounts. There must be
advancement of observation precision throughcomparative observations with the development of avariety of winter precipitation (snow fall) sensors, such as
gravimetric systems and optical systems, in addition to the
WMO
standard
measurements—Double
FencedIntercomparison Reference—used in calibrating trap rates
of fixed rainfall. It is important to also improve theprecision of the spatial precipitation observations by using
observations taken by precipitation radar of changes overtime and space of water vapor (clouds) and fallen snow
particles, and by comparing this with precipitation
satellite data (GPM/DPR and successive machine data).

(3) Permafrost
What's required for research into the ice that makes up
permafrost are, similar to research on glaciers and ice
sheet, long-use observation bases, means of transport andmeteorological survey equipment for basic data. Stably
maintaining the observation base for the long term isparticularly necessary for the long-time constants intemperature monitoring at depth; and, the means oftransportation must be available to allow for multipoint
surveying to cover a large expanse in the observations of
the shallow depths, such as the active layers. There isroom for improvement in the current state of permafrost
drilling technology. Also, with the idea in mind that166

Figure 69: Field equipment and facilities for glacier and ice sheet research.

satellite-based observations, aircraft-based observations
with next-generation sensors (lidar and high-precision
hyperspectral cameras) that can precisely observe
terrestrial ecosystems are also desirable. In understanding
the structure of forests trees using lidar observations, theanalysis of spectral reflected image data taken with a highprecision hyperspectral camera enables analysis of thechemical composition of leaves, and such (including
chlorophyll, lignin and cellulose), and research is enabled
into not only material cycles, but also biological diversity
in terms of species composition. We also propose thesetting up of a large-scale device network by placing
interval cameras in numerous locations around the Arctic
circle to gather data by observing changes to vegetationand seasonal characteristics.
Furthermore, to increase the efficiency of observationsin the vast and pristine landscape of the Arctic region, we
propose the following. Hovercraft, which have alreadybeen used to make ocean observations, would prove to bea formidable tool for observations in the tundra, from themarshes and wetlands, unclear in their separation from thesea due to snow, to the continent interior. Since accessing
the regions with both water surfaces and wetlands isdifficult by foot, vehicle or boat, we should envisionobservations around the Siberian coastline using
hovercraft. The development and deployment of datatransmission devices to Japan from observationequipment installed in remote locations is also sorely
needed. Currently, data transmission is done using
satellites, but the transmission of large amounts of Flux
tower observation and image data is not widespread.
Further advancement of large-volume data transmission
systems and transmission satellites would make datacollection, which currently requires massive amounts oflabor and travel costs, drastically easier. Setting up
transmission satellites to be used for data transmission iseffective for developing animal pattern research to track
animal migration and not only land research, but is also
important for atmosphere and ocean observations.

We must develop and improve observation technology forground-based correction and verification of data for snow
accumulation, such as surface snow cover, waterequivalent of snow cover, snow quality, snow impurities,
snow amount on tree canopies in Boreal forests,
sublimation amounts etc. To improve the development ofan algorithm for satellite optical sensors and microwave
sensors.
(5) Land Hydrological Processes
To understand land hydrological processes detailed onsite observations are required of soil moisture,
evapotranspiration amount and runoff, in addition toobservations of precipitation and accumulated snow.
Observations of snow melting in the spring and snow
accumulation in autumn is particularly important inregards to the seasonal advancement predicted with thelarge changes of the future. Observations of vegetationmust occur simultaneously with water/thermal Flux tower
observations of evapotranspiration. Soil moisture isrelated to the depth of permafrost melting and groundtemperature, and the on-site observations of these
phenomena is not easy; however, a spatial understanding
gained through multi-point observation is required. In
being able to carry out observation with Doppler radar in
conjunction with these observations, we can expect tounderstand the local water cycle, including clouds andprecipitation systems. A technique is being developed anddeployed for the laser measurement of stable water
isotopes as a water cycle tracer for soil moisture amounts;
however, field sampling and an analytical technique mustbe established to allow for the whole-scale measurementof precipitation, fallen snow, water moisture, plant
moisture and water vapor.
d. Terrestrial ecosystems/Material Cycles
Since terrestrial ecosystems have a strong effect on
carbon, nitrogen and water, among other materials, there
is a need to focus efforts on future monitoring. As we
described in the section on the atmosphere, enhancing
Flux tower observation and establishing a system that can
carry out stable observations over the long term isimportant. In addition to enhanced remote-sensinge. Ocean
The Arctic region clearly exhibits the effects of global
environmental changes. The changes in the Arctic also, at167construction or recovery of mooring systems in sea ice
areas, and for emergency recoveries of AUVs.
For the use of submersible robots in sea ice areas,
several factors must be given consideration: outfitting it
against cold temperatures, locating it using sonarnavigation system from a ship, and when operating an
AUV, in particular, if it can be securely recovered. The
average depth of the Arctic Ocean is 1,330 meters;
however, since there are deep basins that with a depth of~4,000 meters, having a submersible that can withstandpressures of over 4,000 meters would allow it to venture
throughout almost the entire region of the ocean. Yet,
since a small and easier-to-use submersible robot is ideal,
thought must be given to developing a submersible thatcan withstand the pressures, handle a payload ofobservation instruments and be launchable from a moonpool.

the same time, likely have a major effect on the global
climate system through changes in the atmosphere andocean circulations and in the cryosphere. Explaining
Arctic systems is indispensable to understanding climate
and other global systems, and observational data are thenecessary foundation for this. Central to the Arctic regionis the expansive Arctic Ocean, and thus marine
observation is the cornerstone to this; observation andlong-term monitoring from the sea floor to the atmosphere,
across the expanse of the ocean are required. It is desirable
to have surveys that can assess changes over, at least thesame amount of time and space, as have been observed byresearch vessels in mid and low-latitude oceans. In
particular, we need observations of seasonal and longterm variations in the Arctic Ocean for better
understanding of the earth system as well for adevelopment of exhaustive atmosphere-sea ice-ocean
models.
However, observations in the Arctic Ocean are still
lagging behind due to sea ice, and there are observational
blank spots. To further develop observations in the Arctic
Ocean in the future, we must have an ice breaker that canperform a variety of observations and have high icebreaking capacity. Also, the development of observation
devices that can perform well in areas with sea ice will
also be necessary. In the following, we will describe thetechnical issues involved in operating in sea ice areas andthe observation instruments requiring development.

(3) Moored Ocean Observation Arrays
What is also required is continuous moored observation
at a fixed point in the sea ice zone using ice profiling sonar(IPS), an ultrasonic Doppler flowmeter, a salinity,
temperature and depth sensors to observe the sea ice
dynamics and changes, as well as physical and chemicalchanges in seawater. Additionally, results can be expectedfrom observations by instruments installed on the seafloor
through seafloor seismometers, seafloor pressure gauges
and various chemical sensors to estimate sub-seafloor
structure and the material exchanges between sedimentand sea water. These instruments and systems must be
developed appropriate to observations under sea ice; and,in order to enable them to carry out continuous operations,in particular, it should be kept in mind that the devices
may be installed and recovered by ROVs and other such
submersibles, and certain design factors must be
considered, such as underwater acoustic data transmission,
tidal electricity generation and fuel cells for underwateruse. The question of powering a submersed observation
device, is not a problem particular to the polar region;
however, the difficulties of installing and recovering of
instruments in Arctic Ocean is a problem that ought to beresolved. Moreover, it would also be ideal to develop an
ice-strengthened profiling float, loaded with physical,
biological and chemical sensors that can observe from acertain depth to right under sea ice. In developing a
profiling float, there is difficulty in positioning in the sea
ice zone with GPS and sending and receiving data throughsatellite, therefore, a solution must be devised to build asonar navigation system and a data transmission network
under the sea ice.

(1) Ship-Bound Observation Instruments
Here we refer to ship-bound observation instruments as
the instruments installed on a ship and used to carry out
atmosphere and ocean observations. Since most of theobservation instruments are for observing from aboard a
vessel, we believe there are no major obstacles even in asea ice zone. However, for the observation instrumentsthat use sound, noise from the ship and noise generated by
ice-breaking should be minimal. Some of the observation
instruments that use sound are the strata prober operating
in a low-frequency band, a multi-narrow beamechosounder, and multi-frequency profiling sonar,
operating at a high-frequency in the ultrasonic range. The
frequency range is broad; however, we must consider thefact that surveys can be conducted in the same frequency
ranges as ice-breaking and how we might counter thisphenomenon. Additionally, since the deeper the draft ofan observation vessel, the farther away from the origin ofnoise one can get, we believe that this point should beconsidered when a new observation vessel is constructed.
(2) Submersible Robots
Submersible robot activity, such as with ROVs and
AUVs, is expected in exploration under the sea ice. An
AUV is an autonomous underwater vehicle for unmanned
exploration that is an unmanned robot that can recognize
its surroundings and autonomously determine its course;
it is an exploratory vehicle appropriate for verticaldirection surveys under sea ice and over a wide area. In
contrast, an ROV is a remotely-operated submersible
vehicle for manned exploration that is controlled fromaboard the ship, and can perform detailed observations
under the sea ice or on the seafloor, and can also takesamples. Additionally, ROVs can be used for undersea(4) Coring etc.
Regarding the taking of sediment samples forpaleoenvironmental and paleoclimatic research, in
addition to a normal piston and gravity corer, a giant corer
capable of taking sediment samples of over 60 meters, anda seafloor-stabilized drilling apparatus should be
developed. The seafloor-stabilized drilling apparatus, inparticular, is a rotary-style drilling machine, so it can drill
into the rock bed.
(5) Sea Ice Observation Instruments
To understand the climate system in the Arctic region,168

calculations and large-volume storage to save input/output
data and validation data for models are necessary, and theestablishment of an infrastructural organizing system tohandle them is important.
This organizing system should not be a term-limited
one under specific projects, but must be managed for along term. Currently, GRENE is advancing research
related to numerical modeling in the field of Arctic
climate change; however, all the goals would not be
achieved within the limited project period. The
development of more sophisticated models andcorresponding research should be promoted. There is aninternational program (APPOSITE) regarding thepredictability of Arctic region changes over the seasonal
to interannual timescales; however, the Japanese researchcommunity lacks organizational support for this programand depends on individual efforts. Moreover, whereas the
Arctic regional climate modeling is currently underdevelopment at the Naval Postgraduate School in the US,
no specific activities on it have not started, partly owing
to the lack of an infrastructural organization in Japan as
yet. There exist large-scale, continuous modeling centers(NCAR, ECMWF, UKMO etc.) and data centers (NSIDCetc.) as research infrastructures. Without similar modelingresearch infrastructure in Japan, we may fall behind theworld in cutting-edge research.
Regarding the computational resources, we can utilize
high-performance computers at domestic universities or
research institutions through a public project or paid use;
however, it would be generally difficult to gain enoughresources due to competition with other users. To
guarantee stable resources for model experiments, itwould be ideal for an individual organization to possess
its own supercomputer. The management and operation ofhigh-performance computers and data server system, andthe development of sophisticated models that integrateeach component of atmosphere, ocean, land and ice sheet,and the improvement for the efficient execution require
highly specialized knowledge. Additionally, we certainly
need supporting staffs managing observational andreanalysis data for initial/boundary conditions andvalidation. Coordinators will also be required to lead theunification of the coding rules (programming method) andthe input/output data format, as well as the developmentof analysis techniques and software. In an infrastructuralorganization, not only technicians with a high degree of
specialized knowledge, but also personnel working as anintermediary position between researchers and thetechnicians should be hired for a long period.
As it appears in the above, the infrastructuralorganization is desired to take the lead in participating ininternational research projects, to implement and manage
various sensitivity/ensemble experiments using numericalmodels, and to carry out operational works, such as Arctic
sea ice prediction.

the observation of not only the atmosphere and ocean, butalso sea ice characteristics is required. Of particularimportance is the monitoring of the mass balance andmorphology of sea ice.
The mass balance of sea ice is crucial for having acorrect understanding of the current status of the sea ice in
the Arctic Ocean as it is rapidly decreasing. For thispurpose, the estimation of the thermodynamic growth or
decay amount of sea ice and the outflow amount of sea icefrom the Arctic Ocean is needed. To accurately estimate
the former, on-site meteorological observations and ice
thickness distribution data are required. To do this, if
possible unmanned observation buoys are desirable inaddition to the ship-based observation. For a long time,
meteorological observations in the Arctic Ocean has been
carried out under the auspices of the International Arctic
Buoy Programme with instruments installed on the sea
ice; however, with the significant reduction of sea ice in
the Arctic Ocean this method is facing a difficult problem.
Since ice thickness distribution can be estimated to somedegrees from aerial observation and satellite data, efforts
must be made to preserve the areal density of themeteorological observations by manufacturing strong
buoys that can stand for the measurements in the oceanwith the sufficiently lasting power. For the quantitative
estimation of the latter, it is required to monitor the
thickness distribution and drifting speed of sea ice flowing
out from the Fram Straight with such instruments as ice
profiling sonars.
Regarding the morphology of sea ice, as the fraction ofseasonal sea ice area increases in the Arctic Ocean, there
is a possibility that the deformation processes of sea ice
may be changing. Therefore a reexamination must be doneof the physical processes used in numerical sea ice models.
The characteristics of the spatial distribution of ridges andthe melt ponds on the sea ice surface are particularly
important. Further on-site observations with an aircraftbased 2D laser scanner and video cameras are now
strongly desired to clarify the real situation in the Arctic
Ocean.
(6) Other (Observations on the coastline)
Aside from ship-bound observations, the developmentof observation instruments for the coastal area is necessary.
With moored observations in shallow areas, considerationmust be given towards a structure where the system will
not be dragged by the sea ice in the winter. The
development of a strong platform is necessary, such as theMonbetsu Okhotsk Tower, which allows for samples to betaken under the sea ice even during the winter. Moreover,consideration must be given to aircraft-boundelectromagnetic sea ice thickness measurement andterrestrial magnetism/gravity measurement in the sea
region.
f. Numerical Modeling
Numerical modeling is an indispensable research tool
to have a comprehensive understanding of the swiftlychanging Arctic environment and the Arctic role in global
climate and Japan, and to further predict the future of the
Arctic climate. To these ends, resources for massive

169Chapter 10: Directions and challenges exceeding 10 years
This long-term plan report is not limited to research
projects already undertaken; it goes so far as to suggest a
policy of establishing a challenge on a time scale
exceeding 10 years. We have attempted to establish ahypothetical theory that will be useful in conducting the

research, and to boldly propose a system in which
pioneering achievements can be accomplished. The
following is a brief outline of 15 themes and infrastructure
improvements.

Elucidation of abrupt environmental change in the
Arctic associated with the on-going global warming“Arctic amplification of global warming (Theme 1)”
will focus on energy transport centered around the Arctic
region to clarify the interactions of various elements,
including the upper atmosphere, clouds and aerosol, snow
accumulation, sea ice, and even the mid-level depths ofthe ocean. To develop and use a global system model forthis purpose, it is necessary to systematically obtain not
only the cooperation of modelers in various fields, but also
the data used for model verification. For Japan’scontribution, we will approach responsible bodies tocontinue sensor development and satellite launching inorder to expand satellite observations of various levels
from the upper atmosphere to sea ice. We must also
maintain a system in which field observations of the sea
are performed regularly.
“Mechanisms and influence of sea ice decline (Theme2)” is intended to facilitate the understanding of (andquantify the processes of) oceanic heat transport in therange from directly under the sea ice to the mid-level
depths. In addition, the interaction between theatmosphere—sea ice—and the ocean, through clouds andlow pressure, will be elucidated. With regard to theproperties of the sea ice itself, the formation of melt ponds
and the impact between ice floes will be clarified in detail.
To perform these field observations, it will be necessary
to operate ice-breaker ships. It will also be essential toperform microwave satellite observations, which are notaffected by the weather. Additionally, a sea-ice/ocean
coupled model that can positively handle individual ice
floes or high-density water downwelling will be built.
This model will be used to provide ships with highly
reliable information about Arctic shipping routes.
“Biogeochemical cycles and ecosystem changes(Theme 3)” will focus on continuing observations of theatmosphere, soil, and rivers. To date, these observations
have been conducted mainly in the summer, over long
periods, or throughout the year. The focus of this theme
will also include the expansion of land ecosystemobservation points using satellite data, etc., to obtainrepresentative areal data. At sea, environmental changes
that impact ecosystems will be monitored, including
coastal erosion or permanent melting of permafrost. In
addition, the transport of carbon or nutrients, etc., will belinked to oceanic circulation or vortices. The mostadvanced chemical and biological sensors and sample
collection devices will be installed along with substancesensors at camps on top of the ice and in data gaps toperform year-round observations in order to quantitatively
understand biogeochemical transport and ecosystemchange.
“Ice sheet/glaciers, permafrost, snowfall/snow coverand hydrological cycle (Theme 4)” will substantially
improve satellite observations of ice sheet surfaces andtotal weight, and it will verify the observations using fielddata. At the same time, sufficient information will begathered about the interior of the ice sheets. This theme
will also link experts in physical oceanography to study
interactions with the ocean. Building a permafrost
observation system requires international cooperation,and the aim of this theme as well as Theme 3 will be tooperate a super-site. This effort will contribute toclarifying the effects of the water cycle on the atmosphere,
land surface, and soil over a wide area. Objective analysis
performed regularly by the meteorological agency will be
expanded to include the land water cycle.
“Interactions between the Arctic and the entire earth(Theme 5)” will focus on learning how fluctuations overtime of the atmosphere, sea ice, and the ocean (which are
now apparent as natural fluctuations) change as global
warming progresses. A repeat analysis will be carried out
based on observation and modeling and on data
assimilation over a wide range extending from interaction
with the upper atmosphere above to the formation of theweakening North Atlantic deep water layers below.
Fluctuations of the atmospheric and water cycles based onland and sea distribution even impact the substance cycle
as well as the Arctic Ocean through feedback with theocean circulation. Important information regarding widearea changes in permafrost will be obtained from Theme 4.
“Predicting future environmental conditions of the
Arctic based on paleoenvironmental records (Theme 6)”
will examine past cases of warming or sudden climatechange that could reoccur in the future. The focus will beon their mechanisms with data and models. Efforts will bemade to sample and analyze the polar region’s
characteristic ice cores and the Arctic seabed cores, and to
perform long-term numerical experiments by developing
new indirect indices and using combined climate and ice
sheet models. It will be important also to identify the riseand fall of short-term fluctuations such as Arctic
oscillations. Restoring and clarifying fluctuations in ice
sheets, the ocean or sea ice, land areas, the atmosphere,
etc., including various time scales, will contribute to aquantification of the past amplification of warming and toresearch on climate change.
“Effects of the Arctic environment on human society(Theme 7)” will be an attempt to expand links between thenatural sciences and the humanities and social sciences in
the Arctic. Its aim will be to prepare proposals for nationaland regional governments based on cooperation between
indigenous peoples and immigrants. The proposals will
involve areas such as information about natural disasters
in emergency situations, reducing damage due to global
warming, etc., and introducing carbon credits.
Collaboration with beyond the environmental science
community are essential.

170permafrost appears as ground settlement caused by athermokarst. It is also necessary to observe ground surfacechanges caused by forest fires, and other factors unrelated
to air temperature change. To collect information about
permafrost, it is essential to have a cooperative systemlinked to international observation networks.

Elucidation of environmental change concerning
biodiversity“Effects on terrestrial ecosystems and biodiversity(Theme 8)” will feature observations and monitoring toclarify the impact of global warming and otherenvironmental change on ecosystems. Through thisprocess, as much data as possible will be gathered byinstalling more automatic observation instruments. The
diversity of species in cold regions is relatively low, but
the diversity of the ecological response may be higher.
Therefore, it is vital to perform a close examination ofvulnerability under conditions of environmental change.
Toward that end, spot surveys will be done over wider
areas, and at the same time, the ecosystem of Hokkaido
will be used to study the impact on the ecosystem inside
the Arctic Circle.
“Influence on marine ecosystem and biodiversity(Theme 9)” will clarify the impact on ecosystems ofchanges in the marine environment. The central point of
this long-term concept is the shift northward of the habitat
range accompanying the spread of seasonal sea ice in the
Arctic Ocean. It is easy to imagine the extinction of certain
extant species, and it must be taken seriously that once a
species is extinct, it is not recoverable. To clarify themechanisms of ocean ecosystems, efforts will be made to
fully use ice-breaking observation vessels to monitor
various impacts that occur in conjunction with theprogression of acidification.

Development of methods enabling breakthroughs inenvironmental research
To perform “Sustainable seamless monitoring (ThemeA),” it is important to continuously gather representative
data in order to survey and clarify various changes in theenvironment. Valuable data can be obtained from theinternal structure of ice floes and deep parts of thepermafrost. It is necessary to manage boreholes inpermafrost as well. To gather data in the ocean, it isessential to employ ice-breakers, mooring systems, andremotely operated sensors. On land, it is useful to collectmeteorological, frozen snow, hydrological, vegetation,and soil data at super-sites.
“Earth system-modeling for inter-disciplinary research(Theme B)” focuses on building and testing an earthsystem model that includes constituent elements of the
global environment. Among the elements, there arevariations in the atmosphere, sea ice, the ocean,permafrost, and terrestrial vegetation, as well as theprecision of the key processes and of their impacts onother elements. It is fundamental to explicitly represent a
process in individual element models. For coupled models,
however, it is necessary to use a different parameterization
depending on the purpose of the model. Sensitivity test
results that indicate how an error in the process of a certain
element impacts other elements will be objectively
evaluated.
The aim of “Data assimilation to connect monitoringand modeling (Theme C)” is to challenge the assimilationof data for multi-sphere systems. The difficulty with thislies in differences in time scale, degree of completeness ofthe numerical model, the number of uncertain parameters,
and the amount of data for each element. To overcome thisbarrier, it is necessary to make investments from theobservation and model perspectives. The purposes of thepresent project are to improve the reliability of
meteorological information from inside the Arctic Circle
and to realize practical predictions of the state of the
Arctic Ocean. An international cooperative system is an
essential condition to achieve these goals.

Broad and important subjects on the Arctic
environment“Geospace environment (Theme 10)” will attempt toclarify the atmospheric coupling processes characteristicof polar regions, including the impact of high-energy
particles precipitating from geospace into the middle andupper atmosphere of the Arctic region. At the same time,
it will focus on the latitudinal coupling of the polar upper
atmosphere with mid- and low-latitude regions. To clarify
these processes observationally, and to proceed to
predictive research on space weather, it will be necessary
to organize a system to develop observation bases
centered on large atmospheric radars, terrestrial
multipoint network observations, satellite observations,and comprehensive atmospheric models.
“Interaction of surface environment change with solid
earth (Theme 11)” will clarify the interrelationships of ice
sheet melting, crustal uplift, and mantle viscosity. Field
topography and geological surveys as well as surveying
and observations done for this purpose are difficult andtime-consuming, but they are worth tackling in order topredict future changes in the ocean surface on a global
scale. Applying geological and geophysical methods toclarify the interactions of fluctuations that originate inside
the solid earth (e.g., the formation and division ofsupercontinents) with surface environmental change will
make a great contribution to understanding Earth’s
evolution.
“Basic understanding on formation and transition
process of permafrost (Theme 12)” is intended to establish
basic information about the present state of permafrost
over a wide area. It is particularly necessary to obtainhigher-resolution information about the horizontal
distribution, thickness distribution, and active layer
thickness of the permafrost and the ice, as well as the
carbon content of the permafrost, in order to obtain multipoint data. A conspicuous example of a change in

Building the research infrastructurea. Ships
Ice-breakers for use in research will be newly
constructed with functions far more advanced than thoseof previous ice-breakers. Noteworthy machines andequipment will include moon pools; chemical, biological,
and geological laboratories (including low-temperaturerooms); autonomous underwater vehicles (AUVs) that can
travel under the sea ice for long periods and can beequipped with many types of sensors; remotely operated
vehicles (ROVs) capable of obtaining specimens; long
big-bore piston corers; multi-beam depth sounders to
perform seabed topographic surveys; and sub-bottom
profilers to perform stratigraphic investigations.
b. Satellites
An observation system combining synthetic apertureradar to monitor changes in the mass of glaciers, ice sheet,171sea ice, and frozen snow with laser radar altimeters will
be operated. A satellite to measure gravity will be
developed. A visible light sensor to monitor land andmarine ecosystems will be installed on the GCOMC1/SGLI, which is scheduled to launch in 2016, andrelated organizations will be approached to continue
efforts in this direction.
c. AircraftA system permitting the ownership of airplanes andincorporating the development of instruments for Arctic
observations will be organized. Efforts will also be madeto use drones for atmospheric observations.
d. Network of bases
To continue collecting diverse parameters at the supersite, bases will be maintained through bilateral links on the
Svalbard Islands, in Eastern Siberia, and in Alaska.
Furthermore, the use of observation equipment in
Canada’s high-latitude Arctic region, on the Arctic Ocean
coastline of Russia, and elsewhere will be explored.
e. Data archives
We aim to establish a data center that will facilitate aneven broader use of archives through links between
international databases.
f. Capacity development
To train young Japanese researchers, JCAR will create
links between universities in Japan and universities in
Arctic countries. Besides developing an internshipprogram, summer schools, and a career path, it will
expand the GRENE young researcher dispatch support
program. We will support the development of young
researchers from indigenous peoples.
g. Research organizations (domestic, international)
A top-down type system of national government
agencies and incorporated administrative agencies will beestablished along with an integrated system of bottom-up
type autonomous organizations such as JCAR that will
provide mutual support. Internationally, efforts will bemade so that the status of Japan, which is non-Arctic
country, will be recognized as legitimate.
h. Instruments (atmosphere, upper atmosphere, frozen
snow, land, ocean)
The development of a network of radar that will
monitor the upper atmosphere over a wide area, and of
instruments to analyze aerosol, etc., in frozen snow willcontinue. To observe land vegetation, hyperspectral
cameras capable of clarifying the constituent trees inforests will be operated. Underwater robots will be used
as mobile equipment to deploy instruments in order toefficiently obtain data from under the sea ice.
i. Numerical modeling
In addition to hardware such as large-scale calculation
resources and high-volume storage, it will also beessential to install personnel specializing in model
development and operating hardware. A system will be
put in place to assign research technologists to provide
data, source codes, etc.

172

Chapter 11: Reference
Citation
Theme 1
Baldwin, M. P., and T. J. Dunkerton (1999), Propagation of the Arctic Oscillation from the stratosphere to the troposphere, J.
Geophys. Res., 104, 30937-30946.
Curry, J. A., W. B. Rossow, D. Randall, and J. L. Schramm (1996), Overview of Arctic cloud and radiation characteristics, J. Climate,9, 1731-1764.
Derksen, C., and R. Brown(2012), Spring snow cover extent reductions in the 2008–2012 period exceeding climate model
projections, Geophys. Res. Let., 39, L19504, doi:10.1029/2012GL053387.
Graversen, R. G., T. Mauritsen, M. Tjernström, E. Källén, and G. Svensson (2008), Vertical structure of recent Arctic warming, Nature,451, 53-56.
Hall, A., and X. Qu (2006), Using the current seasonal cycle to constrain snow albedo feedback in future climate change, Geophys.
Res. Lett., 33, doi:10.1029/2005GL025127.
Hwang, Y.-T., D. M. W. Frierson, and J. E. Kay (2011), Coupling between Arctic feedback and changes in poleward energy transport,
Geophys. Res. Lett., 38, L17704, doi: 10.1029/2011GL048546.
Liu, Y., J. R. Key, Z. Liu, X. Wang, and S. J. Vavrus(2012), A cloudier Arctic expected with diminishing sea ice, Geophys. Res. Lett.,
39, L050705, doi: 10.1029/ 2012GL051251.
Manney, G. L., et al. (2011), Unprecedented Arctic ozone loss in 2011, Nature, 478, 469-475.
O’ishi, R. and A. Abe-Ouchi (2011), Polar amplification in the mid‐Holocene derived from dynamical vegetation change with a
GCM, Geophys. Res. Let., 38, L14702.
Oort, A. H. (1971), The Observed Annual Cycle in the Meridional Transport of Atmospheric Energy. J. Atmos. Sci., 28, 325–339.
Perovich, D.K., B. Light, H. Eicken, K.F. Jones, K. Runciman, and S.V. Nghiem (2007), Increasing solar heating of the Arctic Ocean
and adjacent seas, 1979-2005: Attribution and role in the ice-albedo feedback, Geophys. Res. Lett., 34,
doi:10.1029/2007GL031480.
Trenberth, K. E., and D. P. Stepaniak (2003a), Covariability of components of poleward atmospheric energy transports on seasonaland interannual timescales, J. Clim., 16, 3691–3705.
Tucker, C. J., D. A. Slayback, J. E. Pinzon, S. O. Los, R. B. Myneni, and M. G. Taylor (2001), Higher northern latitude normalized difference
vegetation index and growing season trends from 1982 to 1999, Int. J. Biometeorol., 45, 184-190.
Yoshimori, M., A. Abe-Ouchi, M. Watanabe, A. Oka, and T. Ogura (2014), Robust seasonality of Arctic warming processes in two
different versions of MIROC GCM. J. Climate, accepted.

Theme 2Inoue, J., and M. Hori (2011), Arctic cyclogenesis at the marginal ice zone: A contributory mechanism for the temperatureamplification?, Geophys. Res. Lett., 38, doi:10.1029/2011GL047696.
Jackson, J. M., E. C. Carmack, F. A. McLaughlin, S. E. Allen, and R. G. Ingram (2010), Identification, characterization, and changeof the near-surface temperature maximum in the Canada Basin, 1993–2008, J. Geophys. Res., 115, C05021,
doi:10.1029/2009JC005265
McPhee, M. G. (2013), Intensification of geostrophic currents in the Canada Basin, Arctic Ocean, J. Clim., 26, 3130-3138.
Overland, J. E., and M. Wang (2013), When will the summer Arctic be nearly sea ice free?, Geophys. Res. Lett., 40, 2097-2101,
doi:10/1002/grl.50316.
Rampal, P., J. Weiss, C. Dubois, and J.-M Campin (2011), IPCC climate models do not capture Arctic sea ice drift acceleration:
Consequences in terms of projected sea ice thinning and decline, J. Geophys. Res., 116, doi:10.1029/2011JC007110.

Theme 3Bates, N. R., and J. T. Mathis (2009), The Arctic Ocean marine carbon cycle: evaluation of air-sea CO2 exchanges, ocean
acidification impacts and potential feedbacks, Biogeosciences, 6, 2433–2459.
Frey, K. E., and J. W. McClelland (2009), Impacts of permafrost degradation on arctic river biogeochemistry, Hydrol. Process., 23,
169–182, doi: 10.1002/hyp.7196.
Holmes, R. M., J. W. McClelland, B. J. Peterson, S. E. Tank, E. Bulygina, T. I. Eglinton, V. V. Gordeev, T. Y. Gurtovaya, P. A.
Raymond, D. J. Repeta, R. Staples, R. G. Striegl, A. V. Zhulidov, and S. A. Zimov (2012), Seasonal and annual fluxes ofnutrients and organic matter from large rivers to the Arctic Ocean and surrounding seas, Estuaries and Coasts, 35, 369-382,
doi: 10.1007/s12237-011-9386-6.
Intergovernmental Panel on Climate Change (IPCC) (2013a), Climate Change 2013: The Physical Science Basis, Contribution ofWorking Group I to the Fifth Assessment Report of the IPCC, edited by T. F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S. K.
Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P. M. Midgley, Cambridge Univ. Press, Cambridge, U. K. and New York,NY, USA, 1535 pp.

173

Intergovernmental Panel on Climate Change (IPCC) (2013b), Summary for Policymakers. In Climate Change 2013: The PhysicalScience Basis, Contribution of Working Group I to the Fifth Assessment Report of the IPCC, edited by T. F. Stocker, D. Qin,
G.-K. Plattner, M. Tignor, S. K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P. M. Midgley, Cambridge Univ. Press,
Cambridge, U. K. and New York, NY, USA.
Ise, T., A. L. Dunn, S. C. Wofsy, and P. R. Moorcroft (2008), High sensitivity of peat decomposition to climate change through watertable feedback, Nature Geoscience, 1, 763-766.
Kirchman, D. L., X. A. G. Morán, and H. Ducklow (2009), Microbial growth in the polar oceans ― role of temperature and potential
impact of climate change, Nature Reviews in Microbiology, 7, 451- 459.
Lubin and Vogelmann (2010), Observational quantification of a total aerosol indirect effect in the Arctic, Tellus B, 62, 181–189.
Morimoto, S., S. Ishidoya, K.Ishijima, H.Yashiro, T.Umezawa, G. Hashida, S. Sugawara, S. Aoki, T. Nakazawa, and T. Yamanouchi(2010), Temporal variations of atmospheric greenhouse gases and their related gases at Syowa Station, Antarctica and NyÅlesund, Svalbard. Nankyoku Shiryo (Antarctic Records), 54, 374-409. (in Japanese).
Quinn, P. K., G. Shaw, E. Andrew, E. G. Dutton, T. Ruoho-Airola, and S. L. Going (2007), Arctic haze: current trends and knowledge
gaps, Tellus Series B-chemical and Physical Meteorology, 59B, 99–114.
Shakhova, N., I. Semiletov, A. Salyuk, V. Joussupov, D. Kosmach, and Ö. Gustafssonet (2010), Extensive Methane Venting to the
Atmosphere from Sediments of the East Siberian Arctic Shelf, Science, 327, 1246-1250, doi: 10.1126/science.1182221.
Suzuki, R., Y. Kim, R. Ishii (2013), Sensitivity of the backscatter intensity of ALOS/PALSAR to the above-ground biomass and otherbiophysical parameters of boreal forest in Alaska, Polar Science, 7, 100-112.
Yamamoto-Kawai, M., F. McLaughlin, E. Carmack, S. Nishino, and K. Shimada (2009), Aragonite undersaturation in the Arctic
Ocean: Effects of ocean acidification and sea ice melt, Science, 326, 1098-1100.

Theme 4Abe-Ouchi, A., et al. (2013), Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume, Nature, 500, 190-193.
Brown, R.D. and P.W. Mote (2009), The response of northern hemisphere snow cover to a changing climate, Journal of Climate, 22,2124-2145.
Brutsaert, W., and T. Hiyama (2012), The determination of permafrost thawing trends from long-term streamflow measurements with
an application in eastern Siberia, J. Geophys. Res., 117, D22110, doi:10.1029/2012JD018344.
Ekström, G., M. Nettles, and V. C. Tsai (2006), Seasonality and increasing frequency of Greenland glacial earthquakes. Science, 311,
1756–1758.
Gardner, A. S., et al. (2013), A reconciled estimate of glacier contributions to sea level rise: 2003 to 2009, Science, 340(6134), 852–
857, doi: 10.1126/science.1234532
Goodison, B. E., P. Y. T. Louie, and D. Yang (1998), WMO Solid Precipitation Measurement Intercomparison Final Report, Word
Meteorological Organization Instruments and Observing Methods Report No. 67, 212.
Hiyama T., K. Asai, A. B. Kolesnikov, L. A. Gagarin, and V. V. Shepelev (2013), Estimation of the residence time of permafrost
groundwater in the middle of the Lena River basin, eastern Siberia, Environmental Research Letters, 8, 035034.
Iijima, Y., A.N. Fedorov, H. Park, K. Suzuki, H. Yabuki, T.C. Maximov, and T. Ohata (2010), Abrupt increase in soil temperature
under conditions of increased precipitation in a permafrost region, the central Lena River basin. Permafrost and Periglacial
Processes, 21, 30–41.
Iijima, Y., T. Ohta, A. Kotani, A. N. Fedorov, Y. Kodama, and T. C. Maximov (2014), Sap flow changes in relation to permafrost
degradation under increasing precipitation in an eastern Siberian larch forest, Ecohydrology, 7, doi: 10.1002/eco.1366
Jorgenson, M. T., Y. L. Shur, and E. R. Pullman (2006), Abrupt increase in permafrost degradation in Arctic Alaska, GeophysicalResearch Letters, 33, L02503. doi: 1029/2005GL024960
Landerer, F.W., J.O. Dickey, and A Guentner (2010), Terrestrial water budget of the Eurasian pan‐Arctic from GRACE satellite
measurements during 2003–2009. Journal of Geophysical Research: Atmospheres (1984–2012) 115 (D23).
Lemke, P., J. Ren, R.B. Alley, I. Allison, J. Carrasco, G. Flato, Y. Fujii, G. Kaser, P. Mote, R.H. Thomas, and T. Zhang (2007),
Observations: Changes in Snow, Ice and Frozen Ground. In: Climate Change 2007: The Physical Science Basis, Contributionof Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by S.
Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K. B. Averyt, M. Tignor, and H.L. Miller, Cambridge University Press,
Cambridge, United Kingdom and New York, NY, USA.
Matsumura, S., K. Yamazaki, and T. Tokioka (2010), Summertime land-atmosphere interactions in response to anomalous springtime
snow cover in northern Eurasia, J. Geophys. Res., 115, D20107.
Nitu R. (2013), Cold as SPICE, Meteorological Technology International, 148–150.
Ogawa, R., B.F. Chao, and K. Heki (2010), Seasonal and inter-annual gravity changes in the Siberian permafrost region. Chikyu
Monthly, 32, 234-238. (in Japanese).
Ohta, T., A. Kotani, Y. Iijima, T. C. Maximov, S. Ito, M. Hanamura, A. V. Kononov, and A. P. Maximov (2014), Effects ofwaterlogging on water and carbon dioxide fluxes and environmental variables in a Siberian larch forest, 1998 – 2011, Agric.
For. Meteorol., 188, 64-75.
Park H., J. Walsh, A. N. Fedorov, A. B. Sherstiukov, Y. Iijima, and T. Ohata (2013), The influence of climate and hydrologicalvariables on opposite anomaly in active-layer thickness between Eurasian and North American watersheds, Cryosphere, 7,
631-645, doi:10.5194/tc-7-631-2013.

174

Rasmussen, R., and Coauthors (2012), How well are we measuring snow: The NOAA/FAA/NCAR winter precipitation test Bed.
Bull, Amer. Meteor. Soc., 93, 811–829. doi: http://dx.doi.org/10.1175/BAMS-D-11-00052.1
Romanovsky, V. E., D. S. Drozdov, N. G. Oberman, et al. (2010), Thermal state of permafrost in Russia, Permafrost Periglac.
Process., 21(2), 136–155, doi:10.1002/ppp.683.
Shepherd, A., et al. (2012), A reconciled estimate of ice-sheet mass balance. Science, 338 (6111), 1183–1189,
doi:10.1126/science.1228102
Shur, Y., K. M. Hinkel, and F. E. Nelson (2005), The Transient Layer: Implication for Geocryology and Climate-Change Science,
Permafrost and Periglacial Processes, 16, 5-17.
Sugiura, K., and T. Ohata (2008), Large-scale characteristics of the distribution of blowing snow sublimation, Annals of Glaciology,
49, 11-16.
Suzuki, K., J. Kubota, Y. Zhang, T. Kadota, T. Ohata, and V. Vuglinsky (2006), Snow ablation in an open field and larch forest of thesouthern mountainous region of eastern Siberia, Hydrol. Sci. J., 51(3), 465–480, doi:10.1623/hysj.51.3.465.
Takeuchi, N., S. Kohshima, and K. Seko (2001), Structure, formation, and darkening process of albedo-reducing material(cryoconite) on a Himalayan glacier: a granular algal mat growing on the glacier, Arctic, Antarctic, and Alpine Research, 33,
115–122.
Toyokuni, G., M. Kanao, Y. Tono, T. Himeno, S. Tsuboi, D. Childs, K. Anderson, and H. Takenaka (2014), Japanese Contribution to
the Greenland Ice Sheet Monitoring Network (GLISN), Antarctic Report, in press.
Yallop, M. L., A. M. Anesio, R. G. Perkins, J.Cook, J. Telling, D. Fagan, J. MacFarlane, M. Stibal, G. Barker, C. Bellas, A. Hodson,
M. Tranter, J. Whadhan, and N. W. Roberts (2012), Photophysiology and albedo-changing potential of the ice algal
community on the surface of the Greenland ice sheet, The ISME journal, 6(12), 2302–2313.
Yoshimori, M., and A. Abe-Ouchi (2012), Sources of spread in multi-model projections of the Greenland ice-sheet surface massbalance, J. Climate, 25(4), 1157–1175.
Zhang K., J. Kimball, Q. Mu, L. A. Jones, S. J. Goetz, and S. W. Running (2009), Satellite based analysis of northern ET trends andassociated changes in the regional water balance from 1983 to 2005. J. Hydrol., 379, 92–110,
doi:10.1016/j.jhydrol.2009.09.047.
Zhang, X., J. He, J. Zhang, I. Polaykov, R. Gerdes, J. Inoue, and P. Wu (2013), Enhanced poleward moisture transport and amplified
northern high-latitude wetting trend, Nature Climate Change, 3, 47-51, doi:10.1038/NCLIMATE1631.

Theme 5
Beare, R.J., M. K .Macvean, A. A. M. Holtslag, J. Cuxart, I. Esau, J.-C. Golatz, M. A. Jimenez, M. Khairoutidinov, B. Kosovic, D.
Lewellen, T. S. Lund, J. K. Lundquist, A. Mccabe, A. F. Moene, Y. Noh, S. Raasch, and P. Sullivan (2006), An
intercomparison of large-eddy simulations of the stable boundary layer, Boundary-Layer Meteor., 118, 247-272.
Brown, R., C. Derksen, and L. Wang (2010), A multi-data set Analysis of Variability and Change in Arctic Spring snow Cover Extent,
1967-2008, J. Geophys. Res., 115, D16111, doi:10.1029/JD013975.
Chapman, W.L., and J. E. Walsh (2007), Simulations of Arctic temperature and pressure by global coupled models, J. Clim., 20, 609632, doi:10.1175/JCLI4026.1.
Dickson, B., I. Yashayaev, J. Meincke, B. Turrel, S. Dye, and J. Holfort (2002), Rapid freshening of the deep North Atlantic Ocean
over the past four decades. Nature, 416, 832-837.
Fereday, D., J. R. Knight, A. A. Scaife, C. K. Folland, and A. Philipp (2008), Cluster analysis of North Atlantic European weather
types, J. Clim., 21, 3687-3703.
Groisman P. Y., and T. D. Davies (2001), Snow cover and the Climate System, In Snow Ecology: An Interdisciplinary Examination of
Snow-Covered Ecosystems, edited by H. G. Jones, et al., pp. 1-44, Cambridge University Press.
Honda, M., J. Inoue, and S. Yamane (2009), Influence of low Arctic sea-ice minima on anomalously cold Eurasian winters, Geophys.
Res. Lett., 36, L08707, doi:10.1029/2008GL037079.
Hu, A., G. A. Meehl, W. Han, A. Timmermann, B. Otto-Bliesner, Z. Liu, W. M. Washington, W. Large, A. Abe-Ouchi, M. Kimoto, K.
Lambeck, and B. Wu (2012), Role of the Bering Strait on the hysteresis of the ocean conveyor belt circulation and glacial
climate stability, PNAS, 109(17), 6417-6422.
Ineson, S., and A. A. Scaife (2009), The role of the stratosphere in the European climate response to El Niño, Nature Geoscience, 2,32-36.
Inoue, J., M. E. Hori, and K. Takaya (2012), The Role of Barents Sea Ice in the Wintertime Cyclone Track and Emergence of a
Warm-Arctic Cold-Siberian Anomaly, J. Climate, 25, 2561–2568. doi:http://dx.doi.org/10.1175/JCLI-D-11-00449.1.
Liston, G.E. (2004), Representing Subgrid Snow Cover Heterogeneities in Regional and Global Models, J. Clim., 17, 1381-1397.
Steele, M., and W. Ermold (2007), Steric sea level change in the Northern Seas, J. Clim, 20(3), 403–417.
Tape, K., M. Sturm, and C. Racine (2006), The evidence for shrub expansion in Northern Alaska and the Pan-Arctic, Global Change
Biology, 12, 686-702.
Zhang, T. (2005), Influence of the Seasonal Snow Cover on the Ground Thermal Regime: An Overview, Rev. Geophys., 43, RG4002.
doi: 10.1029/2004RG000157.

175

Theme 6
Abe-Ouchi, A., F. Saito, K. Kawamura, M. E. Raymo, J. Okuno, K. Takahashi, and H. Blatter (2013), Insolation-driven 100,000-year
glacial cycles and hysteresis of ice-sheet volume, Nature, 500(7461), 190–193, doi:10.1038/nature12374.
Bindschadler, R. A., S. Nowicki, A. Abe-Ouchi, A. Aschwanden, H. Choi, J. Fastook, G. Granzow, R. Greve, G. Gutowski, U.
Herzfeld, C. Jackson, J. Johnson, C. Khroulev, A. Levermann, W. H. Lipscomb, M. A. Martin, M. Morlighem, B. R. Parizek,
D. Pollard, S. F. Price, D. Ren, F. Saito, T. Sato, H. Seddik, H. Seroussi, K. Takahashi, R. Walker, and W. L. Wang (2013),
Ice-sheet model sensitivities to environmental forcing and their use in projecting future sea level (the SeaRISE project), J.
Glaciol., 59(214), 195–224, doi:10.3189/2013JoG12J125.
de Vernal, A., C. Hillaire-Marcel, A. Rochon, B. Fréchette, M. Henry, S. Solignac, and S. Bonnet (2013), Dinocyst-based
reconstructions of sea ice cover concentration during the Holocene in the Arctic Ocean, the northern North Atlantic Ocean
and its adjacent seas, Quat. Sci. Rev., 79, 111–121, doi:10.1016/j.quascirev.2013.07.006.
Harrison, S. P., and C. I. Prentice (2003), Climate and CO2 controls on global vegetation distribution at the last glacial maximum:
analysis based on palaeovegetation data, biome modelling and palaeoclimate simulations, Global Change Biology, 9(7), 983–
1004, doi:10.1046/j.1365-2486.2003.00640.x.
Iizuka, Y., R. Uemura, H. Motoyama, T. Suzuki, T. Miyake, M. Hirabayashi, and T. Hondoh (2012), Sulphate–climate coupling overthe past 300,000 years in inland Antarctica, Nature, 490(7418), 81–84, doi:10.1038/nature11359.
Intergovernmental Panel on Climate Change (IPCC) (2013), Climate Change 2013: The Physical Science Basis, Contribution ofWorking Group I to the Fifth Assessment Report of the IPCC, edited by T. F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S. K.
Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P. M. Midgley, Cambridge Univ. Press, Cambridge, U. K. and New York,NY, USA, 1535 pp.
Joussaume, S., K. E. Taylor, P. Braconnot, J. F. B. Mitchell, J. E. Kutzbach, S. P. Harrison, I. C. Prentice, A. J. Broccoli, A. AbeOuchi, P. J. Bartlein, C. Bonfils, B. Dong, J. Guiot, K. Herterich, C. D. Hewitt, D. Jolly, J. W. Kim, A. Kislov, A. Kitoh, M. F.
Loutre, V. Masson, B. McAvaney, N. McFarlane, N. de Noblet, W. R. Peltier, J. Y. Peterschmitt, D. Pollard, D. Rind, J. F.
Royer, M. E. Schlesinger, J. Syktus, S. Thompson, P. Valdes, G. Vettoretti, R. S. Webb, and U. Wyputta (1999), Monsoon
changes for 6000 years ago: Results of 18 simulations from the Paleoclimate Modeling Intercomparison Project (PMIP),
Geophys Res Lett, 26(7), 859–862, doi:10.1029/1999GL900126.
Kobashi, T., D. T. Shindell, K. Kodera, J. E. Box, T. Nakaegawa, and K. Kawamura (2013), On the origin of multidecadal tocentennial Greenland temperature anomalies over the past 800 yr, Clim. Past, 9(2), 583–596, doi:10.5194/cp-9-583-2013.
Lambert, F., J.-S. Kug, R. J. Park, N. Mahowald, G. Winckler, A. Abe-Ouchi, R. O’ishi, T. Takemura, and J.-H. Lee (2013), The roleof mineral-dust aerosols in polar temperature amplification, Nature Climate Change, 3(5), 487–491,
doi:10.1038/nclimate1785.
Meyer, H., L. Schirrmeister, A. Andreev, D. Wagner, H.-W. Hubberten, K. Yoshikawa, A. Bobrov, S. Wetterich, T. Opel, E. Kandiano,
and J. Brown (2010), Lateglacial and Holocene isotopic and environmental history of northern coastal Alaska – Results froma buried ice-wedge system at Barrow, Quat. Sci. Rev., 29(27-28), 3720–3735, doi:10.1016/j.quascirev.2010.08.005.
Moran, K., J. Backman, H. Brinkhuis, S. C. Clemens, T. Cronin, G. R. Dickens, F. Eynaud, J. Gattacceca, M. Jakobsson, R. W.
Jordan, M. Kaminski, J. King, N. Koç, A. Krylov, N. Martinez, J. Matthiessen, D. McInroy, T. C. Moore, J. Onodera, M.
O'Regan, H. Palike, B. Rea, D. Rio, T. Sakamoto, D. C. Smith, R. Stein, K. St John, I. Suto, N. Suzuki, K. Takahashi, M.
Watanabe, M. Yamamoto, J. Farrell, M. Frank, P. Kubik, W. Jokat, and Y. Kristoffersen (2006), The Cenozoic
palaeoenvironment of the Arctic Ocean, Nature, 441(7093), 601–605.
NEEM community members (2013), Eemian interglacial reconstructed from a Greenland folded ice core, Nature, 493(7433), 489–
494, doi:10.1038/nature11789.
O’ishi, R. and A. Abe-Ouchi (2011), Polar amplification in the mid-Holocene derived from dynamical vegetation change with a
GCM, Geophys Res Lett, 38, L14702, doi:10.1029/2011GL048001.
PALAEOSENS Project Members (2012), Making sense of palaeoclimate sensitivity, Nature, 491(7426), 683–691,
doi:doi:10.1038/nature11574.
Pollack, H. N. (2003), Surface temperature trends in Russia over the past five centuries reconstructed from borehole temperatures, J.
Geophys. Res., 108(B4), 2180, doi:10.1029/2002JB002154.
Sigl. M., J. R. McConnell, M. Toohey, M. Curran, S.B. Das, R. Edwards, E. Isaksson, K. Kawamura, J. Kipfstuhl, K. Krüger, L.
Layman, O.Maselli, Y. Motizuki, H. Motoyama, D. Pasteris, and M. Severi (2014), New insights from Antarctica on volcanic
forcing during the Common Era, Nature Clim. Change, in press.
Sueyoshi, T., R. Ohgaito, A. Yamamoto, M. O. Chikamoto, T. Hajima, H. Okajima, M. Yoshimori, M. Abe, R. O’ishi, F. Saito, S.
Watanabe, M. Kawamiya, and A. Abe-Ouchi (2013), Set-up of the PMIP3 paleoclimate experiments conducted using an
Earth system model, MIROC-ESM, Geoscientific Model Development, 6(3), 819–836, doi:10.5194/gmd-6-819-2013.
Uemura, R., V. Masson-Delmotte, J. Jouzel, A. Landais, H. Motoyama, and B. Stenni (2012), Ranges of moisture-source temperature
estimated from Antarctic ice cores stable isotope records over glacial–interglacial cycles, Clim. Past, 8(3), 1109–1125,
doi:10.5194/cp-8-1109-2012.
Yoshimura, K., T. Miyoshi, M. Kanamitsu (2014), Observation System Simulation Experiments using Water Vapor Isotope
Information, J. Geophys. Res. Atmos., in press, doi:10.1029/2014JD021662.
Zachos, J., M. Pagani, L. Sloan, E. Thomas, and K. Billups (2001), Trends, Rhythms, and Aberrations in Global Climate 65 Ma to
Present, Science, 292(5), 686–693, doi:10.1126/science.1059412.

176

Theme 7
SGEPSS (2013), Current status and future plan of Geomagnetism and Earth, Planetary and Space Sciences. SGEPSS, p291. (inJapanese).
Kaeriyama, M., H. Seo, H. Kudo, and M. Nagata (2012), Perspectives on wild and hatchery salmon interactions at sea, potential
climate effects on Japanese chum salmon, and the need for sustainable salmon fishery management reform in Japan, Environ.
Biol. Fish., 94, 165-177.
Kelly, R., M. L. Chipman, P. E. Higuera, I. Stefanova, L. B. Brubaker, and F. S. Hu (2013), Recent burning of boreal forests exceeds
fire regime limits of the past 10,000 years, PNAS, 110-32, 13055–13060.
Kitagawa H., N. Ono, H. Yamaguchi, K. Izumiyama, K. Kamesaki (2000), Northern Sea Route. Ship and Ocean Foundation. P242
(in Japanese).
Koshino, Y., H. Kudo, and M. Kaeriyama (2013), Stable isotope evidence indicates the incorporation of marine-derived nutrientstransported by spawning Pacific salmon to Japanese catchments. Freshwater Biology, 58, 1864-1877.
Post, E., U. S. Bhatt, C.M. Bitz, J. F. Brodie, T. L. Fulton, M. Hebblewhite, J. Kerby, S. J. Kutz, I. Stirling, D. A. Walker (2013),
Ecological Consequences of Sea-Ice Decline, Science, 341(6145), 519-524, doi:10.1126/science.1235225.
SATREPS Project. http://www.jst.go.jp/global/kadai/h2004_indonesia.html.
Steppuhn, H. (1981), Snow and Agriculture, Handbook of Snow, 60-125, Pergamon Press.
Symon C., L. Arris, and B. Heal (Eds.) (2005), Arctic climate impact assessment, Cambridge Univ. Press, New York.
Tanaka, H. L. (2008),
Relationship between the abnormal weather in Japan and the Arctic Oscillation. Proceeding of Heavy Snow Disaster
Prevention, 2008. Snow and Ice Research Center, National Research Institute for Earth Science and Disaster Prevention. 1-6,
2008. (in Japanese).
Tsuboi, S., D. Komatitsch, C. Ji, and J. Tromp (2003), Broadband modeling of the 2002 Denali fault earthquake on the Earth
Simulator, Physics of The Earth and Planetary Interiors, doi:10.1016/j.pepi.2003.09.012.
Yamaguchi, H. (2013), Sea ice prediction and construction of an ice navigation support system for the Arctic sea routes, Proc. 22ndIntern. Conf. on Port and Ocean Eng. under Arctic Conditions (POAC’13), Espoo, Finland, June 9-13, 2013.

Theme 8
Cardinale B. (2012), Impacts of Biodiversity Loss, Science, 336, 552-553.
Clymo R.S. (1983), Peat, In Ecosystems of the world, 4A Mires: swamp bog, fen and moor, general studies, edited by A. J. P. Gore,
159-224R, Elsevier, Amsterdam.
Clymo, S., and P. M. Hayward (1982), The ecology of Sphagnum, In Bryophyte Ecology, edited by A. J. E. Smith, 229-289, Chapman
and Hall, London, England.
Elmqvist, T., C. Folke, M. Nyström, G. Peterson, J. Bengtsson, B. Walker, J. Norberg (2003), Response diversity, ecosystem change,
and resilience, Frontiers in Ecology and the Environment, 1, 488-494.
Ganter, B., A. J. Gaston (2013), Birds, In Arctic Biodiversity Assessment, edited by H. Meltofte, 142-181, The Conservation of Arctic
Flora and Fauna (CAFF), Akureyri, Iceland.
Ise, T., H. Sato (2008), Representing subgrid-scale edaphic heterogeneity in a large-scale ecosystem model: A case study in thecircumpolar boreal regions, Geophysical Research Letters, 35, L20407, doi:10.1029/2008GL035701.
Loreau, M., S. Naeem, P. Inchausti, J. Bengtsson, J. P. Grime, A. Hector, D. U. Hooper, M. A. Huston, D. Raffaelli, B. Schmid, D.
Tilman, D. A. Wardle (2001), Biodiversity and Ecosystem Functioning: Current Knowledge and Future Challenges, Science,
294, 804-808.
Mäkilä, M., M. Saarnisto, T. Kankainen (2001), Aapa mires as a carbon sink and source during the Holocene, Journal of Ecology, 89,
589-599.
Mori, A. S., T. Furukawa, T. Sasaki (2013), Response diversity determines the resilience of ecosystems to environmental change,
Biological Reviews, 88, 349-364.
Post, E., U. S. Bhatt, C. M. Bitz, J. F. Brodie, T. L. Fulton, M. Hebblewhite, J. Kerby, S. J. Kutz, I. Stirling, D. A. Walker (2013),
Ecological Consequences of Sea-Ice Decline, Science, 341, 519-524.
Purves, D., J. P. W. Scharlemann, M. Harfoot, T. Newbold, D. P. Tittensor, J. Hutton, S. Emmott (2013), Ecosystems: Time to model
all life on Earth, Nature, 493, 295-297.
Tsuyuzaki, S., K. Kushida, Y. Kodama (2009), Recovery of surface albedo and plant cover after wildfire in a Picea mariana forest ininterior Alaska, Climate Change, 93, 517-525.

Theme 9Abdul-Aziz, O. I., N. J. Mantua, and K. W. Myers (2011), Potential climate change impacts on thermal habitats of Pacific salmon(Oncorhynchus spp.) in the North Pacific Ocean and adjacent seas, Can. J. Fish. Aquat. Sci., 68, 1660-1680.
AMAP(2009), Arctic Pollution 2009, Arctic Monitoring and Assessment Programme, Oslo. xi+83pp.
AMAP (2013), AMAP Assessment 2013, Arctic Ocean Acidification. Arctic Monitoring and Assessment Programme (AMAP), Oslo,
Norway. viii + 99 pp.
Bluhm, B. A., A. V. Gebruk, R. Gradinger, R. R. Hopcroft, F. Huettmann, K. N. Kosobokova,B. I. Sirenko, and J. M. Weslawski

177

(2011), Arctic marine biodiversity: An update of species richness and examples of biodiversity change, Oceanography, 24,
232–248.
Boetius, A., S. Albrecht, K. Bakker, C. Bienhold, J. Felden, and others (2013), Export of algal biomass from the melting Arctic sea
ice, Science, 339, 1430-1432.
Buchholz, et al. (2012), First observation of krill spawning in the high Arctic Kongsfjorden, west Spitsbergen. Polar Biol., 35, 12731279.
CAFF (2013), Life Linked to Ice: A guide to sea-ice-associated biodiversity in this time of rapid change, CAFF Assessment Series
10, p. 115.
CoML (2010), First Census of Marine Life 2010, Highlights of a decade of discovery, edited by J. H. Ausubel, p. 64.
Cooper et al. (2013), Linkages between sea-ice coverage, pelagic–benthic coupling, and the distribution of spectacled eiders:
Observations in March 2008, 2009 and 2010, northern Bering Sea. Deep-Sea Res. II, 94, 31-43.
Grebmeier, J.M. et al. (2006) Ecosystem dynamics of the Pacific-influenced Northern Bering and Chukchi Seas, Prog. Oceanogr.,
71, 331-361.
Honjo, S., R. A. Krishfield, T. I. Eglinton, S. J. Manganini, J. N. Kemp, K. Doherty, J. Hwang, T. K. McKee, T. Takizawa (2010),
Biological pump processes I the cryopelagic and hemipelagic Arctic Ocean: Canada Basin and Chukchi Rise, Progress in
Oceanography, 85, 137-170.
Kaeriyama, M. (2008), Ecosystem-based sustainable conservation and management of Pacific salmon, In Fisheries for Global
Welfare and Environment, edited by K. Tsukamoto, T. Kawamura, T. Takeuchi, T. D. Beard, Jr., and M. J. Kaiser, 371-380,
TERRAPUB, Tokyo.
Kaeriyama, M., H. Seo, H. Kudo, and M. Nagata (2012), Perspectives on wild and hatchery salmon interactions at sea, potential
climate effects on Japanese chum salmon, and the need for sustainable salmon fishery management reform in Japan, Environ.
Biol. Fish., 94, 165-177.
Kaeriyama, M., H. Seo, and Y. Qin (2014), Effect of global warming on the life history and population dynamics of Japanese chumsalmon, Fisheries Sci., 80 (2), 251-260.
Koshino, Y., H. Kudo, and M. Kaeriyama (2013), Stable isotope evidence indicates the incorporation of marine-derived nutrientstransported by spawning Pacific salmon to Japanese catchments, Freshwater Biology, 58, 1864-1877.
McClelland, J. W., R. M. Holmes, K. H. Dunton, and R. W. Macdonald (2012), The Arctic Ocean Estuary, Estuaries and Coasts, 35,353-368.
Mallory, and Braune (2012), Tracking contaminants in seabirds of Arctic Canada: temporal and spatial insights. Mar. Pollut. Bull.,64, 1475-1484.
Matsuno, et al. (2011), Year-to-year changes of the mesozooplankton community in the Chukchi Sea during summers of 1991, 1992
and 2007, 2008. Polar Biol., 34, 1349-1360.
Michelutti et al. (2009), Seabird-driven shifts in Arctic pond ecosystems. Proc. R. Soc. B, 276, 591-596.
Orr, J.C., et al. (2005), Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms.
Nature, 437, 681-686.
Pabi, et al. (2008), Primary production in the Arctic Ocean, 1998–2006. J. Geophys. Res., Doi:10.1029/2007JC004578.
Tremblay, J.-É., and J. Gagnon (2009), The effects of irradiance and nutrient supply on the productivity of Arctic waters: aperspective on climate change, 73-92, In Influence of Climate Change on the Changing Arctic and Sub-Arctic Conditions,edited by J. C. J. Nihoul, and A. G. Kostianoy, Springer, Dordrecht, Netherlands.
Uchimiya, M., H. Fukuda, S. Nishino, T. Kikuchi, H. Ogawa, T. Nagata (2011), Does freshening of surface water enhanceheterotrophic prokaryote production in the western Arctic? Empirical evidence from the Canada Basin during September
2009, Journal of Oceanography, 67, 589–599.
Wassmann, P.(1998), Retention versus export food chains: processes controlling sinking loss from marine pelagic systems,
Hydrobiologia, 36, 29-57.
Wassmann, P. (2011), Arctic marine ecosystems in an era of rapid climate change, Progress in Oceanography, 90, 1-17

Theme 10Baldwin, M. P., and T. J. Dunkerton (1999), Propagation of the Arctic Oscillation from the stratosphere to the troposphere, J.
Geophys. Res., 104, 30937-30946.
Chau, J. L., L. P. Goncharenko, B. G. Fejer, and H.L. Liu (2012), Equatorial and low latitude ionospheric effects during sudden
stratospheric warming events, Space Sci Rev, 168, 385–417, DOI 10.1007/s11214-011-9797-5.
SGEPSS (2013), Current status and future plan of Geomagnetism and Earth, Planetary and Space Sciences. SGEPSS, p291. (inJapanese).
Gray, L. J., J. Beer, M. Geller, J. D. Haigh, M. Lockwood, K. Matthes, U. Cubasch, D. Fleitmann, G. Harrison, L. Hood, J.
Luterbacher, G. A. Meehl, D. Shindell, B. van Geel, and W. White (2010), Solar Influences on Climate, Reviews ofGeophysics, 48, 1209/10/2009RG000282, 2010.
Jackman, C. H., et al. (2001), Northern Hemisphere atmospheric effects due to the July 2000 solar proton event, Geophys. Res. Lett.,
28, 2883-2886.
Jin, H., Y. Miyoshi, H. Fujiwara, H. Shinagawa, K. Terada, N. Terada, M. Ishii, Y. Otsuka, and A. Saito (2011), Vertical connection
from the tropospheric activities to the ionospheric longitudinal structure simulated by a new Earth’s whole atmosphere‐178ionosphere coupled model, J. Geophys. Res., 116, A01316, doi:10.1029/2010JA015925.
Makela J. J., and Y. Otsuka (2012), Overview of Nighttime Ionospheric Instabilities at Low- and Mid-Latitudes: Coupling Aspects
Resulting in Structuring at the Mesoscale, Space Science Reviews, 168, 419-440.
Manney, G. L., et al. (2011), Unprecedented Arctic ozone loss in 2011, Nature, 478, 469-475.
Plumb, R. A., and K. Semeniuk (2003), Downward migration of extratropical zonal wind anomalies, J. Geophys. Res., 108, 4223,
doi:10.1029/2002JD002773.
Randall, C. E., V. L. Harvey, C. S. Singleton, S. M. Bailey, P. F. Bernath, M. Codrescu, H. Nakajima, and J. M. Russell (2007),
Energetic particle precipitation effects on the Southern Hemisphere stratosphere in 1992-2005, J. Geophys. Res., 112,
D08308, doi:10.1029/2006JD007696.
Rishbeth, H., and O. K. Garriott (1969), Introduction to ionospheric physics, International Geophysics Series, 14, Academic Press,
New York.
Roble, R. G., and R. E. Dickinson (1989), How will changes in carbon dioxide and methane modify the mean structure of themesosphere and thermosphere?, Geophys. Res. Lett., 16, 1441-1444.
Rozanov, E., et al. (2005), Atmospheric response to NOy source due to energetic electron precipitation, Geophys. Res. Lett., 32,
L14811, doi:10.1029/2005GL023041.
Shiota, D., S. Tsuneta, M. Shimojo, N. Sako, D. Orozco Suarez, and R. Ishikawa (2012), Polar Field Reversal as observed with
Hinode, The Astrophysical Journal, arXiv:1205.2154 [astro-ph.SR].
Schunk, R. W., and A. F. Nagy (2000), Ionospheres: Physics, plasma physics, and chemistry, Cambridge University Press.
Tsugawa, T., et al. (2011), Ionospheric disturbances detected by GPS total electron content observation after the 2011 off the Pacificcoast of Tohoku Earthquake, Earth, Planets and Space, 63, 875-879.
Turner, J., J. E. Overland, and J. E. Walsh (2007), An Arctic and Antarctic perspective on recent climate change, Int. J. Climatol., 27,277-293.
Vadas, S. L., and G. Crowley (2010), Sources of the traveling ionospheric disturbances observed by the ionospheric TIDDBIT
sounder near Wallops Island on 30 October 2007, J. Geophys. Res., 115, A07324, doi:10.1029/2009JA015053.

Theme 11
Alvey, A., C. Gaina, N. J. Kusznir, T. H. Torsvik (2008), Integrated crustal thickness mapping and plate reconstructions for the highArctic, Earth Planet Sci. Lett., 274, 310–321.
Backman, J., K. Moran, L. A. Mayer, D. B. McInroy, and the Expedition 302 Scientists (2006), Proceedings IODP, 302, College
Station TX (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.302.104.
Barletta, V., and A. Bordoni (2009), Clearing observed PGR in GRACE data aimed at global viscosity inversion: Weighted Mass
Trends technique, Geophys. Res. Lett., 36, L02305, doi:10.1029/2008GL036429.
Barnett, T. P. (1984), The Estimation of "Global" Sea Level Change' A Problem of Uniqueness, J. Geophys. Res., 89, C5, 7980-7988.
Bowring, S. A., I. S. Williams, W. Compston (1989), 3.96 Ga gneisses from the Slave province, Northwest Territories, Canada,
Geology, 17, 971-975.
Carson, C. J., S. McLaren, A. L. Roberts, S. D. Boger, D. D. Blankenship (2014), Hot rocks in a cold place: high sub-glacial heatflow in East Antarctica, Journal of Geological Society of London, 171, doi.org/10.1144/jgs2013-030.
Edmonds, H. N. et al. (2003), Discovery of abundant hydrothermal venting on the ultraslow-spreading Gakkel ridge in the Arctic
Ocean, Nature, 421, 252-256.
Ekman, M., and J. Mäkinen (1996), Recent postglacial rebound, gravity change and mantle flow in Fennoscandia, Geophys. J. Int.,
126, 229–234.
Glebovsky, V. Y. , L. C. Kovacs, S. P. Maschenkov, J. M. Brozena (1998), Joint compilation of Russian and US Navy aeromagnetic
data in the central Arctic seas, Roland, N., F. Tessesnsons (Eds.), ICAM III; Third International Conference on Arctic
Margins, Polarforshungpp, 35–40.
Jakobsson, M., R. Macnab, L. Mayer, R. Anderson, M. Edwards, J. Hatzky, H. W. Schenke, and P. Johnson (2008), An improved
bathymetric portrayal of the Arctic Ocean: Implications for ocean modeling and geological, geophysical and oceanographic
analyses, Geophysical Research Letters, doi:10.1029/2008GL033520.
Jokat, W. (2003), Seismic investigations along the western sector of Alpha Ridge, Central Arctic Ocean, Geophysical JournalInternational, 152 (1), 185-201.
Lebedeva-Ivanova, N. N., Y. Ya. Zamansky, A. E. Langinen, and M. Yu. Sorokin (2006), Seismic profiling across the Mendeleev
Ridge at 82°N: evidence of continental crust, Geophysical Journal International, 165, 527–544. doi: 10.1111/j.1365246X.2006.02859.x
Lorenz, H., D. G. Gee, A. N. Larionov, J. Majka (2012), The Grenville–Sveconorwegian orogen in the high Arctic, Geological
Magazine, 149, 875-891.
Michael, P. J. et al. (2003), Magmatic and amagmatic seafloor generation at the ultraslow-spreading Gakkel ridge, Arctic Ocean,
Nature, 423, 956-961.
Moran, K. et al. (2006), The Cenozoic palaeoenvironment of the Arctic Ocean, Nature, 441(7093), 601–605.
Nutman, A. P., V. C. Bennett, C. R. L. Friend, K. Horie, H. Hidaka (2007), ~3850 Ma tonalites in the Nuuk region, Greenland:geochemistry and their reworking within an Eoarchaean gneiss complex, Contributions to Mineralogy and Petrology, 154,
385-408.

179

Pedersen, R. B. et al. (2010), Discovery of a black smoker vent field and vent fauna at the Arctic mid-ocean ridge, Nature
Communications, 1, http://dx.doi .org/10.1038/ncomms1124.
Peltier, W. R.(2004), Global glacial isostasy and the surface of the ice-age Earth: The ICE-5G (VM2) model and GRACE, Annu. Rev.
Earth Planet. Sci., 32, 111-149.
Sella, G., S. Stein, T. Dixon, M. Craymer, T. James, S. Mazzotti, and R. Dokka (2007), Observation of glacial isostatic adjustment in‘‘stable’’ North America with GPS, Geophys. Res. Lett., 34, L02306, doi:10.1029/2006GL027081.
Seton, M., R. D. Muller, S. Zahirovic, C. Gaina, T. Torsvik, G. Shephard, A. Talsma, M. Gurnis, M. Turner, S. Maus, M. Chandler(2012), Global continental and ocean basin reconstructions since 200 Ma, Earth-Science Reviews, 113, 212-270.
Shank, T., J. Bailey, H. Edmonds, P. Forte, E. Helmke, et al. (2007), Biological and geological characteristics of the Gakkel Ridge,
Eos Trans. AGU Fall Meeting Supplement, OS41C-08, 88.
Sohn, R.A., et al. (2008), Explosive volcanism on the ultraslow-spreading Gakkel ridge, Arctic Ocean, Nature, 453, 1236-1238.
Vernikovsky, V. A., N. L.Dobretsov, D. V. Metelkin, N.Yu. Matushkin, I.Yu. Koukakov (2013), Concerning tectonics and the tectonic
evolution of the Arctic, Russian Geology and Geophysics, 54, 838-858.
Verhoef, J., W. R. Roest, R. Macnab, J. Arkani-Hamed (1996), Magnetic anomalies of the Arctic and North Atlantic oceans andadjacent land areas.
Vogt, P. R., P. T. Taylor, L.C. Kovacs, and G. L. Johnson (1982), The Canada Basin; aeromagnetic constraints on structure andevolution, Tectonophysics, 89, 295–336.

Theme 12
Brown, J., O. J. Ferrians, Jr, J. A. Heginbottom, and E. S. Melnikov (1997), Circum-arctic map of permafrost and ground ice
conditions. United States Geological Survey, published for the International Permafrost Association, Circum-Pacific Map
Series, Map CP-45, scale 1:10,000,000.
Brown, J., O. J. Ferrians, Jr., J. A. Heginbottom, and E. S. Melnikov (2002), Circum-Arctic Map of Permafrost and Ground-Ice
Conditions, Version 2, National Snow and Ice Data Center, Boulder, Colorado USA.
Francis, J. A., D. M. White, J. J. Cassano, W. J. Gutowski, Jr., L. D. Hinzman, M. M. Holland, M. A. Steele, and C. J. Vörösmarty(2009), An Arctic hydrologic system in transition: feedbacks and impacts on terrestrial, marine, and human life. Journal ofGeophysical Research, 114, G04019.
Harris, C. et al. (2009), Permafrost and climate in Europe: Monitoring and modelling thermal, geomorphological and geotechnicalresponses, Earth-Science Reviews, 92 (3-4), 117-171
Ishikawa, M. and K. Saito (2006), Frozen ground sciences influencing climate and water cycle -Reviews and perspectives-. Journalof the Japanese Society of Snow and Ice, 68, 639-656. (in Japanese).
Ishikawa, M., N. Sharkhuu, Y. Jambaljav, G. Davaa, K. Yoshikawa, and T. Ohata (2012), Thermal states of Mongolian permafrost,
173-178, Proc, 10th Int. Conf. Permafrost, Salehard.
Koven, C. D., B. Ringeval, P. Friedlingstein, P. Ciais, P. Cadule, D. Khvorostyanov, G. Krinner, and C. Tarnocai (2011), Permafrost
carbon-climate feedbacks accelerate global warming, Proc. Natl Acad. Sci., 108, 14769–74.
Lachenbruch, A. H., and B. V. Marshall (1986), Changing climate: geothermal evidence from permafrost in the Alaskan Arctic,
Science, 234, 689-696.
Matsuoka, N. and A. Ikeda (2012), Research Frontier in Periglacial Processes. Journal of Geography (Chigaku Zasshi), 121(2), 269–
305. (in Japanese).
Romanovsky, V. E. et al. (2010), Thermal state of permafrost in Russia, Permafrost and Periglacial Processes, 21 (2), 136-155
Saito, K., T. Zhang, D. Yang, S. Marchenko, R. G. Barry, V. Romanovsky, and L. Hinzman (2013), Influence of the physicalterrestrial Arctic in the eco-climate system, Ecological Applications, 23, 1778–1797.
Schaefer, K., H. Lantuit, V. E. Romanovsky, and E. A. G. Schuur (2012), Policy Implications of Warming Permafrost, 31 pp., UNEP.
Schirrmeister, L., D. Froese, V. Tumskoy, G. Grosse, and S. Wetterich (2013), Yedoma: Late Pleistocene Ice-Rich Syngenetic
Permafrost of Beringia, in Encyclopedia of Quaternary Science (Second Edition), edited by S. A. Elias, pp. 542–552,
Elsevier.
Schuur, E.A.G., and B. Abbott (2011), High risk of permafrost thaw, Nature, 480(7375), 32-33.
Shur, Y. L., and M. T. Jorgenson (2007), Patterns of permafrost formation and degradation in relation to climate and ecosystems,
Permafrost and Periglacial Processes 18, 7–19.
Singh, V. P., P. Singh and U. K. Haritashya (Eds.) (2011), Encyclopedia of Snow, Ice and Glaciers, 844, Springer, doi: 10.1007/97890-481-2642-2.
Slater and Lawrence (2013), Diagnosing Present and Future Permafrost from Climate Models, J. Clim., 26(15), 5608-5623, doi:
10.1175/JCLI-D-12-00341.1.
Tarnocai, C., J. G. Canadell, E. A. G. Schuur, P. Kuhry, G. Mazhitova and S. Zimov (2009), Soil organic carbon pools in the northern
circumpolar permafrost region, Global Biogeochemical Cycles, 23, GB2023, doi:10.1029/2008GB003327.
United Nations Environment Programme (2012), Policy implications of warming permafrost.
Vonk, J. E., P. J. Mann, K. L. Dowdy, A. Davydova, S. P. Davydov, N. Zimov, R. G. M. Spencer, E. B. Bulygina, T. I. Eglinton, andR. M. Holmes (2013), Dissolved organic carbon loss from Yedoma permafrost amplified by ice wedge thaw, Environ. Res.
Lett., 8, 035023, doi:10.1088/1748-9326/8/3/035023.
Zhang, T., R. G. Barry, K. Knowles, J. A. Heginbottom, and J. Brown (1999), Statistical and characteristics of permafrost and180ground-ice distribution in the Northern Hemisphere, Polar Geogr., 23, 132-154.
Zimov, S. A., E. A. G. Schuur, and F. S. Chapin III (2006), Permafrost and the global carbon budget, Science, 312, 1612-1613.

Theme A
Bolch, T. et al. (2013), Mass loss of Greenland's glaciers and ice caps 2003–2008 revealed from ICESat data, Geophysical. Research
Letters, 40, 875–881, doi:10.1002/grl.50270.
Comiso, J. C., and F. Nishio (2008), Trends in the sea ice cover using enhanced and compatible AMSR-E, SSM/I, and SMMR data, J.
Geophys. Res., 113, C02S07, doi:10.1029/2007JC004257.
Fukuda, M. (1993), Genesis and occurrence of ice complex (Edoma) in lowland area along Arctic coast of east Siberia near Tiksi, In
Proceedings of the First Symposium on Joint Siberian Permafrost Studies between Japan and Russia in 1992, 101-103.
Grebmeier, J. M., Moore, S. E., Overland, J. E., Frey, K. E., and Gradinger, R. (2010), Biological Response to Recent Pacific Arctic
Sea Ice Retreats, EOS Trans. AGU, 91(18), doi:10.1029/2010EO180001.
Hori, M., T. Aoki, K. Stamnes, and W. Li (2007), ADEOS-II/GLI snow/ice products - part III: Retrieved results, Remote Sens.
Environ., 111, 274−319, doi:10.1016/j.rse.2007.01.025.
Kawamiya, M., T. Hajima, and T. Tokioka (2012), Foreseeing the forests: vegetation dynamics in an Earth system model, In Forest
for people, Tudor Rose, Leicester, England, 291-294.
Keeling, C. D., R. B. Bacastow, A. E. Bainbridge, C. A. Ekdahl, Jr., P. R. Guenther, L. S. Waterman, and J. F. S. Chin (1976),
Atmospheric Carbon Dioxide Variations at Mauna Loa Observatory, Hawaii, Tellus, 28, 538-551.
Key, J., M. Drinkwater, and J. Ukita (2007), Integrated Global Observing Strategy - Partnership (IGOS-P) Cryosphere Theme Report,
World Meteorological Organization, 132 pp, Geneva.
Moon T. et al. (2012), 21st-century evolution of Greenalnd outlet glacier velocities, Science 336(6081), 576–578, doi:
10.1126/science.1219985.
Morimoto, S., S. Aoki, T. Nakazawa and T. Yamanouchi (2006), Temporal variations of the carbon isotopic ratio of atmosphericmethane observed at Ny Ålesund, Svalbard from 1996 to 2004, Geophys. Res. Lett., 33, L01807,
doi:10.1029/2005GL024648.
Quinn, P. et al. (2007), Arctic haze: current trends and knowledge gaps, Tellus Series B-chemical and Physical Meteorology,
doi:10.1111/j.1600-0889.2006.00238.x
Serreze, M. C., A. P. Barrett, A. G. Slater, M. Steele, J. Zhang, and K. E. Trenberth (2007), The large-scale energy budget of the
Arctic, J. Geophys. Res., 112, D11122, doi:10.1029/2006JD008230.
Steffen, K., and J. E. Box (2001), Surface climatology of the Greenland ice sheet: Greenland climate network 1995-1999, J.
Geophys. Res., 106 (D24), 33,951-33,964, doi:10.1029/2001JD900161.
Suzuki, R. (2013), A review of recent studies on vegetation in boreal regions by remote sensing. Journal of The Remote Sensing
Society of Japan33, 48-55. (in Japanese).
Tape, K., M. Sturm, and C. Racine (2006), The evidence for shrub expansion in Northern Alaska and the Pan-Arctic, Global Change
Biology, 12, 686-702.
Ueyama, M., H. Iwata, and Y. Harazono (2014), Autumn warming reduces the CO2 sink of a black spruce forest in interior Alaska
based on a nine-year eddy covariance measurement, Global Change Biology, 20, 1161-1173.
Vaughan, D. G., J. C. Comiso, I. Allison, J. Carrasco, G. Kaser, R. Kwok, P. Mote, T. Murray, F. Paul, J. Ren, E. Rignot, O.
Solomina, K. Steffen, and T. Zhang (2013), Observations: Cryosphere, In Climate Change 2013: The Physical Sci- ence
Basis, Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change,
edited by T. F.Stocker, D. Qin, G.-K. Plattner, M. Tignor, S. K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex, and P. M.
Midgley,. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Viereck, L. A., N. R. Werdin-Pfisterer, P. C. Adams, and K. Yoshikawa (2008), Effect of Wildfire and Fireline Construction on the
Annual Depth of Thaw in a Black Spruce Permafrost Forest in Interior Alaska: A 36-Year Record of Recovery, In
Proceedings of the Ninth International Conference on Permafrost, 1845-1850, Fairbanks, Alaska.
Wang, X., and J. Key (2005), Arctic Surface, Cloud, and Radiation Properties Based on the AVHRR Polar Pathfinder Dataset, Part II:
Recent Trends, Journal of Climate, 18(14), 2575-2593.
Wientjes, I. G. M., R. S. W. Van de Wal, G. J. Reichart, A. Sluijs, and J. Oerlemans (2007), Dust from the dark region in the western
ablation zone of the Greenland ice sheet, The Cryosphere, 5, 589-601, doi:10.5194/tc-5-589-2011.
Yamanouchi, T. (2011), Early 20th century warming in the Arctic: A review, Polar Science, doi:10.1016/j.polar.2010.10.002.

Theme B
Bindschadler, R., S. Nowicki, A. Abe-Ouchi, A. Aschwanden, H. Choi, J. Fastook, G. Granzow, R. Greve, G. Gutowski, U. Herzfeld,
C. Jackson, J. Johnson, C. Khroulev, A. Levermann, W. Lipscomb, M. Martin, M. Morlighem, B. Parizek, D. Pollard, S.
Price, D. Ren, F. Saito, T. Sato, H. Seddik, H. Seroussi, K. Takahashi, R. Walker and W. L. Wang (2013), Ice-sheet model
sensitivities to environmental forcing and their use in projecting future sea level (the {SeaRISE} project), J. Glaciol., 59,
195-224.
De Boer, G., M. D. Shupe, P. M. Caldwell, S. E. Bauer, O. Persson, J. S., Boyle, M. Kelley, S. A. Klein, and M. Tjernstrom (2014),
Near-surface meteorology during the Arctic Summer Cloud Ocean Study (ASCOS): evaluation of reanalysis and global
climate models, Atmos. Chem Phys., 14, 427-445,

181www.atmos-chem-phys.net/14/427/2014/ , doi:10.5194/acp-14-427-2014.
Ise, T., A. L. Dunn, S. C. Wofsy, and P. R. Moorcroft (2008), High sensitivity of peat decomposition to climate change through watertable feedback, Nature Geoscience, 1, 763-766.
Jahn et al. (2012), Late-twentieth-century simulation of Arctic sea ice and ocean properties in the CCSM4, J. Climate, 25, 1431-1452.
Jakobsson, M., L. A. Mayer, B. Coakley, J. A. Dowdeswell, S. Forbes, B. Fridman, H. Hodnesdal, R. Noormets, R. Pedersen, M.
Rebesco, H.-W. Schenke, Y. Zarayskaya A, D. Accettella, A. Armstrong, R. M. Anderson, P. Bienhoff, A. Camerlenghi, I.
Church, M. Edwards, J. V. Gardner, J. K. Hall, B. Hell, O. B. Hestvik, Y. Kristoffersen, C. Marcussen, R. Mohammad, D.
Mosher, S. V. Nghiem, M. T. Pedrosa, P. G. Travaglini, and P. Weatherall,(2012) The International Bathymetric Chart of the
Arctic Ocean (IBCAO) Version 3.0, Geophysical Research Letters, doi: 10.1029/2012GL052219.
O'ishi, R. and A. Abe-Ouchi (2009), Influence of dynamic vegetation on climate change arising from increasing CO2, Climate
Dynamics, 33, 645-663.
Proshutinsky, A., and Coauthors (2011), Recent advances in Arctic ocean studies employing models from the Arctic Ocean Model
Intercomparison Project, Oceanography, 24(3), 102-113.
Proshutinsky, A., and Z. Kowalik (2007), Preface to special section on Arctic Ocean Model Intercomparison Project (AOMIP)
Studies and Results, J. Geophys. Res., 112, C04S01, doi:10.1029/2006JC004017.
Satoh, M., T. Matsuno, H. Tomita, H. Miura, and T. Nasuno (2008), Nonhydrostatic icosahedral atmospheric model (NICAM) for
global cloud resolving simulation. J. Comp. Phys., 227, 3486-3514.
Sueyoshi, T., R. Ohgaito, A. Yamamoto, M. O. Chikamoto, T. Hajima, H. Okajima, M. Yoshimori, M. Abe, R. O'ishi, F. Saito, S.
Watanabe, M. Kawamiya and A. Abe-Ouchi (2013), Set-up of the PMIP3 paleoclimate experiments conducted using an Earthsystem model, MIROC-ESM, Geosci. Model Dev., 6, 819-836.
Taylor, K. E., R. J. Stouffer, and G. a. Meehl (2012), An Overview of CMIP5 and the Experiment Design, Bull. Am. Meteorol. Soc.,
93, 485–498.
Watanabe, M., and Coauthors (2010), Improved climate simulation by MIROC5: Mean states, variability, and climate sensitivity, J.
Climate, 23, 6312-6355.
Yi, S. H., M. K. Woo and M. A. Arain (2007), Impacts of peat and vegetation on permafrost degradation under climate warming.
Geophys. Res. Lett., 34(16), L16504.

Theme C
Awaji, T., M. Kamachi, M. Ikeda and Y. Ishikawa (2009), Ocean data assimilation: innovation to combine observation, experimentand modeling. Kyoto Univ. Press, pp.284. (in Japanese).
Bourassa,et al. (2013), High-latitude ocean and sea-ice surface fluxes: Challenges for climate research, Bull. Amer. Meteor. Soc.,
94(3), 403–423, doi:10.1175/BAMS-D-11-00244.1.
Dameris, M. and P. Jöckel (2013), Numerical modelling of climate-chemistry connections: Recent developments and futurechallenges, Atmosphere, 4, 132-156, doi: 10.3390/atmos4020132.
Goldberg, D. N., and P. Heimbach (2013), Parameter and state estimation with a time-dependent adjoint marine ice sheet model, The
Cryosphere Discuss., 7, 2845-2890, doi:10.5194/tcd-7-2845-2013.
Heimbach, P., and V. Bugnion (2009), Greenland ice-sheet volume sensitivity to basal, surface and initialconditions
derived from an adjoint model, Ann. Glaciol., 50, 67–80, doi:10.3189/172756409789624256.
Inoue, J., T. Enomoto, and M. E. Hori (2013), The impact of radiosonde data over the ice-free Arctic Ocean on the atmospherecirculation in the Northern Hemisphere, Geophys. Res. Let., 40, 864-869.
Jakobson, E., T. Vihma, T. Palo, L. Jakobson, H. Keernik, and J. Jaagus (2012), Validation of atmospheric reanalyses over the central
Arctic Ocean, Geophys. Res. Lett., 39, L10802, doi:10.1029/2012GL051591.
Kimball, J. S., L. A. Jones, K. Zhang, F. A. Heinsch, K. C. McDonald, and W. C. Oechel (2009), A satellite approachtoestimate land-atmosphere CO2 exchange for Boreal and Arctic biomes using MODIS and AMSR-E, IEEE Transactions on
Geoscience and Remote Sensing, 47(2), 569-587, 10.1109/TGRS.2008.2003248.
Lindsay, R., C. Haas, S. Hendricks, P. Hunkeler, N. Kurtz, J. Paden, B. Panzer, J. Sonntag, J. Yungel, and J. Zhang (2012), Seasonal
forecasts of Arctic sea ice initialized with observations of ice thickness, Geophys. Res. Lett., 39, L21502,
doi:10.1029/2012GL053576.
Popova et al. (2012), What controls primary production in the Arctic Ocean? Results from an intercomparison of five generalcirculation models with biogeochemistry, J. Geophys. Res., 117, doi:10.1029/2011JC007112.
Toyoda et al. (2011), Impact of the assimilation of sea ice concentration data on an atmosphere-ocean-sea ice coupled simulation of
the Arctic ocean climate, SOLA, 7, 37-40, doi:10.2151/sola.2011-010.
Toyoda et al. (2013). Improved state estimations of lower trophic ecosystems in the global ocean based on a Green’s function
approach, Prog. Oceanogr., 119, 90-107.
Usui, N, T. Imaizumi, H. Tsujino (2010), Toward introduction of assimilation of ice concentration into MOVE/MRI.COM: A model
validation and a simple assimilation experiment in the Sea of Okhotsk. Weather service bulletin 77, Special issue, S71-S82.
(in Japanese).
Valsala, K. V. and S. Maksyutov (2010), Simulation and assimilation of global ocean pCO2 and air-sea CO2 fluxes using shipobservations of surface ocean pCO2 in a simplified biogeochemical offline model, Tellus, 62B, 821–840, doi:10.1111/j.16000889.2010.00495.x.

182

<Authors, reviewers and JCAR Long-term planning working group members’ Name list in alphabeticalorder by theme.>

JCAR Long-term planning working group members (Since Feb, 2013)
FUJII Yoshiyuki (SOKENDAI / NIPR), IKEDA Motoyoshi (Hokkaido University), ISE Takeshi (Kyoto University), KODAMA
Yuji (NIPR), OHATA Tetsuo (JAMSTEC / NIPR), SUGIYAMA Shin (Hokkaido University), WATANABE Eiji (JAMSTEC), YAMAMOTO-KAWAI Michiyo (Tokyo University of Marine Science and Technology), YAMANOUCHI Takashi (NIPR / The
SOKENDAI), YOSHIDA Ryuhei (Tohoku University), YOSHIMORI Masakazu (Hokkaido University)* JAMSTEC: Japan Agency for Marine-Earth Science and Technology*NIPR: National Institute of Polar Research*SOKENDAI: SOUKENDAI (The Graduate University for Advanced Studies)

Authors and reviewers
Chaptor 1～4, and 10

JCAR Long‐term planning working group members
Chaptor 5～8<Theme 1: Arctic amplification of global warming >lead author: AOKI Teruo
second lead author: ABE-OUCHI Ayako, ENOMOTO Hiroyuki、YOSHIMORI Masakazu
ABE Manabu (Japan Agency for Marine-Earth Science and Technology), ABE-OUCHI Ayako (University of Tokyo), AOKI Kazuma(University of Toyama), AOKI Teruo (Meteorological Research Institute), ENOMOTO Hiroyuki (NIPR / SOKENDAI), FUJIWARA
Hitoshi (Seikei University), HASUMI Hiroyasu (The University of Tokyo), HIROTA Nagio (NIPR / The University of Tokyo),
HONDA Meiji (Niigata University), HORI Masatake (JAMSTEC), IKEDA Motoyoshi (Hokkaido University), INOUE Jun (NIPR /SOKENDAI), ISHII Masayoshi (Meteorological Research Institute), KOMURO Yoshiki (JAMSTEC), MIYOSHI Yasunobu (Kyushu
University), O’ISHI Ryouta (NIPR / The University of Tokyo), OGAWA Yasunobu (NIPR / SOKENDAI), OHATA Tetsuo(University of Bern), OKAMOTO Hajime (Kyushu University), SAKANOI Kazuyo (Komazawa University), SATOH Masaki (The
University of Tokyo), SHIOBARA Masataka (NIPR / SOKENDAI), SUMATA Hiroshi (The Alfred Wegener Institute), SUZUKI
Rikie (JAMSTEC), TAKEMURA Toshihiko (Kyushu University), TOMIKAWA Yoshihiro (NIPR / SOKENDAI), WATANABE
Masahiro (The University of Tokyo), YAMANOUCHI Takashi (NIPR / SOKENDAI), YAMAZAKI Koji (NIPR / Hokkaido
University), YOSHIMORI Masakazu (Hokkaido University), YOSHIMURA Kei (The University of Tokyo)

Reviewer: FUJII Yoshiyuki (SOKENDAI / NIPR)<Theme 2: Mechanisms and Influence of Sea Ice Decline >lead author: WATANABE Eiji
second lead author: OHSHIMA Kay I.
HIRANO Daisuke (NIPR), IKEDA Motoyoshi (Hokkaido University), INOUE Jun (NIPR / SOKENDAI), KAWAGUCHI Yusuke(The University of Washington), KIMURA Noriaki (NIPR / The University of Tokyo), MIZOBATA Kohei (Tokyo University ofMarine Science and Technology), NIHASHI Sohei (Tomakomai National College of Technology), NISHIOKA Jun (Hokkaido
University), NOMURA Daiki (Hokkaido University), OHSHIMA Kay I. (Hokkaido University), ONO Jun (NIPR / The University ofTokyo), TAMURA Takeshi (NIPR / SOKENDAI), TOYODA Takahiro (Meteorological Research Institute), TOYOTA Takenobu(Hokkaido University), WATANABE Eiji (JAMSTEC)

Reviewer: KIKUCHI Takashi (JAMSTEC), HASUMI Hiroyasu (The University of Tokyo)<Theme 3: Biogeochemical cycles and ecosystem changes >lead author: SUZUKI Rikie
second lead author: HARADA Naomi
AOKI Shuji (Tohoku University), CHIKITA Kazuhisa (Hokkaido University), HARA Keiichiro (Fukuoka University), HARA
Toshihiko (Hokkaido University), HARADA Naomi (JAMSTEC), HAYASAKA Hiroshi (Hokkaido University), HIRAWAKE Toru
(Hokkaido University), ISE Takeshi (Kyoto University), ISHIKAWA Mamoru (Hokkaido University), KOJIMA Satoru (Northern
Oikoscape Research Atelier), KUMA Kenshi (Hokkaido University), MATSUOKA Atsushi (Université Laval), MATSUURA Yojiro(Forestry and Forest Products Research Institute), MORISHITA Tomoaki (Forestry and Forest Products Research Institute), NAGATA
Toshi (The University of Tokyo), NISHINO Shigeto (JAMSTEC), NISHIOKA Jun (Hokkaido University), O’ISHI Ryouta (NIPR /The University of Tokyo), OHATA Tetsuo (JAMSTEC / NIPR), PARK Hotaek (JAMSTEC), SAITO Kazuyuki (JAMSTEC), SAMPEI
Makoto (Hiroshima University), SUGIMOTO Atsuko (Hokkaido University), SUZUKI Rikie (JAMSTEC), UCHIDA Masaki (NIPR

183

/ SOKENDAI), WATANABE Yutaka (Hokkaido University), YAMAMOTO-KAWAI Michiyo (Tokyo University of Marine Scienceand Technology), YAMANOUCHI Takashi (NIPR / SOKENDAI)

Reviewer: SAIGUSA Nobuko (NIPR), SASAKI Hiroshi (Ishinomaki Senshu University)<Theme 4: Ice sheet / glaciers, permafrost, snowfall / snow cover and hydrological cycle >lead author: IIJIMA Yoshihiro
second lead author: SUGIYAMA Shin
ABE-OUCHI Ayako (The University of Tokyo), AOKI Teruo (Meteorological Research Institute), ENOMOTO Hiroyuki (NIPR /SOKENDAI), FUJII Yoshiyuki (SOKENDAI / NIPR), GOTO-AZUMA Kumiko (NIPR / SOKENDAI), HIRASAWA Naohiko (NIPR/ SOKENDAI), IIJIMA Yoshihiro (JAMSTEC), ISHIKAWA Mamoru (Hokkaido University), IWAHANA Go (University of Alaska),
KANAO Masaki (NIPR / SOKENDAI), KAWAMURA Kenji (NIPR / SOKENDAI / JAMSTEC), MATOBA Sumito (Hokkaido
University), OHATA Tetsuo (JAMSTEC / NIPR), OHSHIMA Kazuhiro (JAMSTEC), OHTA Takeshi (Nagoya University), PARK
Hotaek (JAMSTEC), SAITO Fuyuki (JAMSTEC), SUEYOSHI Tetsuo (NIPR / JAMSTEC), SUGIURA Konosuke (University of
Toyama), SUGIYAMA Shin (Hokkaido University), SUZUKI Kazuyoshi (JAMSTEC), TAKEUCHI Nozomu (Chiba University),
TSUBOI Seiji (JAMSTEC), YAMAMOTO-KAWAI Michiyo (Tokyo University of Marine Science and Technology), YAMAZAKI
Takeshi (Tohoku University), YOSHIMURA Kei (The University of Tokyo)

Reviewer: TAKAHASHI Shuhei (Kitami Institute of Technology), HIYAMA Tetsuya (Nagoya University)<Theme 5: Interactions between the Arctic and the entire earth >lead author: TAKAYA Koutarou
second lead author: TAKATA Kumiko
FUJIWARA Hitoshi (Seikei University), HASUMI Hiroyasu (The University of Tokyo), HIROTA Nagio (NIPR / The University ofTokyo), HONDA Meiji (Niigata University), HORI Masatake (JAMSTEC), IKEDA Motoyoshi (Hokkaido University), INOUE Jun(NIPR / SOKENDAI), MIYOSHI Yasunobu (Kyushu University), MIZOBATA Kohei (Tokyo University of Marine Science andTechnology), NAKAMURA Hisashi (The University of Tokyo), OGAWA Yasunobu (NIPR / SOKENDAI), SAKANOI Kazuyo(Komazawa University), SUZUKI Rikie (JAMSTEC), TACHIBANA Yoshihiro (Mie University), TAKATA Kumiko (NIPR /National Institute for Environmental Studies), TAKAYA Koutarou (Kyoto Sangyo University), TANAKA L. Hiroshi (University ofTsukuba), TOMIKAWA Yoshihiro (NIPR / SOKENDAI), TOYODA Takahiro (Meteorological Research Institute), UKITA Jinro(Niigata University), WATANABE Masahiro (The University of Tokyo), YAMAZAKI Koji (NIPR / Hokkaido University),
YOSHIDA Ryuhei (Tohoku University)

Reviewer: ICHII Kazuhito (JAMSTEC), EJIRI Mitsumu K. (NIPR / SOKENDAI)KAWAMURA Ryuichi (Kyushu University), KIKUCHI Takashi (JAMSTEC)<Theme 6: Predicting future environmental conditions of the Arctic based on paleoenvironmental records >lead author: KAWAMURA Kenjisecond lead author: YAMAMOTO Masanobu, YOSHIMURA Kei
ABE-OUCHI Ayako (The University of Tokyo), FUJII Yoshiyuki (SOKENDAI / NIPR), GOTO-AZUMA Kumiko (NIPR /SOKENDAI), HARADA Naomi (JAMSTEC), IIZUKA Yoshinori (Hokkaido University), IWAHANA Go (University of Alaska),
KAWAMURA Kenji (NIPR / SOKENDAI / JAMSTEC), KOBASHI Takuro (University of Bern), MATOBA Sumito (Hokkaido
University), MIURA Hideki (NIPR / SOKENDAI), O’ISHI Ryouta (NIPR / The University of Tokyo), OKUNO Jun’ichi (NIPR /JAMSTEC), SAITO Fuyuki (JAMSTEC), SEKI Osamu (Hokkaido University), SUEYOSHI Tetsuo (NIPR / JAMSTEC),SUGANUMA Yusuke (NIPR / SOKENDAI), UEMURA Ryu (University of the Ryukyus), YAMAMOTO Masanobu (Hokkaido
University), YOSHIMORI Masakazu (Hokkaido University), YOSHIMURA Kei (The University of Tokyo)

Reviewer: TAKAHASHI Kozo (Hokusei Gakuen University) ICHII Kazuhito (JAMSTEC),HORIUCHI Kazuho (Hirosaki University)<Theme 7: Effects of the Arctic environment on human society >lead author: IKEDA Motoyoshi
second lead author: TAKAKURA Hiroki
ARAKIDA Hazuki (Institute of Physical and Chemical Research), HAYASAKA Hiroshi (Hokkaido University), IKEDA Motoyoshi(Hokkaido University), MATSUMURA Kanichiro (Tokyo University of Agriculture, Department of Business Science and Regional
Development, Faculty of Bioindustry), MIYOSHI Yoshizumi (Nagoya University), OTSUKA Yuichi (Nagoya University), SAITOH
Sei-Ichi (Hokkaido University), SATO Atsushi (National Research Institute for Earth Science and Disaster Prevention), TAKAKURA
Hiroki (Tohoku University), TATSUZAWA Shirow (Hokkaido University), TSUBOI Seiji (JAMSTEC), YAMAGUCHI Hajime (The
University of Tokyo)

Reviewer: KISHIGAMI Nobuhiro (National Museum of Ethnology)
KITAGAWA Hiromitsu (Ocean Policy Research Foundation)

184

<Theme 8: Effects on terrestrial ecosystems and biodiversity >lead author: HARA Toshihikosecond lead author: ISE Takeshi
ARAKIDA Hazuki (Institute of Physical and Chemical Research), HAJIMA Tomohiro (JAMSTEC), HARA Toshihiko (Hokkaido
University), HARAGUCHI Akira (The University of Kitakyushu), HAYASAKA Hiroshi (Hokkaido University), ISE Takeshi (Kyoto
University), KOJIMA Satoru (Northern Oikoscape Research Atelier), OHATA Tetsuo (JAMSTEC / NIPR), SUZUKI Rikie(JAMSTEC), TAKAHASHI Hideki (Hokkaido University), TATSUZAWA Shirow (Hokkaido University), TSUYUZAKI Shiro(Hokkaido University), YOSHIDA Ryuhei (Tohoku University)

Reviewer: FUJIMAKI Yuzo (Obihiro University of Agriculture and Veterinary Medicine)<Theme 9: Influence on marine ecosystem and biodiversity >lead author: HIRAWAKE Toru
second lead author: WATANUKI Yutaka
HATTORI Hiroshi (Tokai University), HIRAWAKE Toru (Hokkaido University), IIDA Takahiro (NIPR / SOKENDAI), IKEDA
Motoyoshi (Hokkaido University), KAERIYAMA Masahide (Hokkaido University), MATSUNO Kohei (NIPR / Hokkaido University),
ONODERA Jonaotaro (JAMSTEC), SAITOH Sei-Ichi (Hokkaido University), SAMPEI Makoto (Hiroshima University), UCHIMIYA
Mario (NIPR / The University of Tokyo), WATANUKI Yutaka (Hokkaido University), YAMAGUCHI Atsushi (Hokkaido University),
YAMAMOTO-KAWAI Michiyo (Tokyo University of Marine Science and Technology)

Reviewer: HARADA Naomi (JAMSTEC), MITANI Yoko (Hokkaido University)<Theme 10: Geospace Environment >lead author: OGAWA Yasunobu
second lead author: TOMIKAWA Yoshihiro
FUJITA Shigeru (The Meteorological College), FUJIWARA Hitoshi (Seikei University), MIYOSHI Yasunobu (Kyushu University),
MIYOSHI Yoshizumi (Nagoya University), NOZAWA Satonori (Nagoya University), OGAWA Yasunobu (NIPR / SOKENDAI),OTSUKA Yuichi (Nagoya University), SAKANOI Kazuyo (Komazawa University), SHIOKAWA Kazuo (Nagoya University),
TOMIKAWA Yoshihiro (NIPR / SOKENDAI)

Reviewer: NAKAMURA Takuji (NIPR / SOKENDAI)HOSOKAWA Keisuke (The University of Electro-Communications)<Theme 11: Interaction of surface environment change with solid earth >lead author: NOGI Yoshifumi
second lead author: MIURA Hideki
DOI Koichiro (NIPR / SOKENDAI), FUJII Yoshiyuki (SOKENDAI / NIPR), HOKADA Tomokazu (NIPR / SOKENDAI),KAWAMURA Kenji (NIPR / SOKENDAI / JAMSTEC), MIURA Hideki (NIPR / SOKENDAI), NOGI Yoshifumi (NIPR /SOKENDAI), OKUNO Jun’ichi (NIPR / JAMSTEC), SUGANUMA Yusuke (NIPR / SOKENDAI), SUGIYAMA Shin (Hokkaido
University)

Reviewer: OKINO Kyoko (The University of Tokyo), FUKUDA Yoichi (Kyoto University)<Theme 12: Basic understanding on formation and transition process of permafrost >lead author: SUEYOSHI Tetsuo
second lead author: ISHIKAWA Mamoru
FUJII Yoshiyuki (SOKENDAI / NIPR), HARADA Koichiro (Miyagi University), ISHIKAWA Mamoru (Hokkaido University),
IWAHANA Go (University of Alaska), OHATA Tetsuo (JAMSTEC / NIPR), SAITO Kazuyuki (JAMSTEC), SUEYOSHI Tetsuo(NIPR / JAMSTEC)

Reviewer: IKEDA Atsushi (University of Tsukuba), HIYAMA Tetsuya (Nagoya University)< Theme A: Sustainable seamless monitoring >lead author: YAMAZAKI Takeshi
second lead author: TAMURA Takeshi
NIHASHI Sohei (Tomakomai National College of Technology), OHSHIMA Kay I. (Hokkaido University), SUEYOSHI Tetsuo (NIPR/ JAMSTEC), SUGIMOTO Atsuko (Hokkaido University), SUGIYAMA Shin (Hokkaido University), SUZUKI Rikie (JAMSTEC),TAMURA Takeshi (NIPR / SOKENDAI), TOYOTA Takenobu (Hokkaido University), YAMANOUCHI Takashi (NIPR /SOKENDAI), YAMAZAKI Takeshi (Tohoku University)

Reviewer: OHTA Takeshi (Nagoya University)185

< Theme B: Earth system-modeling for inter-disciplinary research >lead author: ABE-OUCHI Ayako
second lead author: KOMURO Yoshiki

ABE-OUCHI Ayako (The University of Tokyo), IKEDA Motoyoshi (Hokkaido University), ISE Takeshi (Kyoto University),
KOMURO Yoshiki (JAMSTEC), O’ISHI Ryouta (NIPR / The University of Tokyo), ONO Jun (NIPR / The University of Tokyo),
SAITO Fuyuki (JAMSTEC), SATO Hisashi (JAMSTEC), SATOH Masaki (The University of Tokyo), WATANABE Eiji (JAMSTEC),YAMAZAKI Takeshi (Tohoku University), YOSHIMORI Masakazu (Hokkaido University)
Reviewer: EMORI Seita (NIPR), TOKIOKA Tatsushi (JAMSTEC)< Theme C: Data assimilation to connect mentoring and modeling >lead author: Wakamatu Tsuyosi
second lead author: IKEDA Motoyoshi
IKEDA Motoyoshi (Hokkaido University), INOUE Jun (NIPR / SOKENDAI), ONO Jun (NIPR / The University of Tokyo), SUMATA
Hiroshi (The Alfred Wegener Institute), TOYODA Takahiro (Meteorological Research Institute), WAKAMATSU Tsuyoshi(JAMSTEC), WATANABE Eiji (JAMSTEC)

Reviewer: ISHII Masayoshi (Meteorological Research Institute)
NAKANO Hideyuki (Meteorological Research Institute)

Chaptor 9: Improvement of Research foundation
ABE-OUCHI Ayako (The University of Tokyo), AOKI Teruo (Meteorological Research Institute), FUJII Yoshiyuki (SOKENDAI /NIPR), FUJIWARA Hitoshi (Seikei University), FURUYA Masato (Hokkaido University), FURUYA Masato (Hokkaido University),
HIRAWAKE Toru (Hokkaido University), HORI Masahiro (Japan Aerospace eXploration Agency), IIJIMA Yoshihiro (JAMSTEC),
IKEDA Motoyoshi (Hokkaido University), ISE Takeshi (Kyoto University), ISHIKAWA Mamoru (Hokkaido University),
KAWAMURA Kenji (NIPR / SOKENDAI / JAMSTEC), KOMURO Yoshiki (JAMSTEC), MIZOBATA Kohei (Tokyo University ofMarine Science and Technology), NISHINO Shigeto (JAMSTEC), NISHIOKA Jun (Hokkaido University), NOGI Yoshifumi (NIPR/ SOKENDAI), NOMURA Daiki (Hokkaido University), OHATA Tetsuo (JAMSTEC / NIPR), OKAMOTO Hajime (Kyushu
University), SAWAGAKI Takanobu, (Hokkaido University), SHIOBARA Masataka (NIPR / SOKENDAI), SUEYOSHI
Tetsuo (NIPR / JAMSTEC), SUGIMOTO Atsuko (Hokkaido University), SUGIYAMA Shin (Hokkaido University),
SUZUKI Rikie (JAMSTEC), TAMURA Takeshi (NIPR / SOKENDAI), TANIKAWA Tomonori (Japan Aerospace
eXploration Agency), TATEYAMA Kazutaka (Kitami Institute of Technology), TOYOTA Takenobu, (Hokkaido
University), WATANABE Eiji (JAMSTEC), YABUKI Hironori (JAMSTEC / NIPR), YAMAMOTO Masanobu(Hokkaido University), YAMAMOTO-KAWAI Michiyo (Tokyo University of Marine Science and Technology),
YAMANOUCHI Takashi (NIPR / SOKENDAI) YOSHIDA Ryuhei (Tohoku University)

186

Steering committee members of Japan Consortium for Arctic Environmental Research・The 1st term (Whereabouts in their term of office thru May 2011 to June 2013)
ABE-OUCHI Ayako (The University of Tokyo), AOKI Teruo (Meteorological Research Institute), ENOMOTO Hiroyuki (NIPR /SOKENDAI), FUKUDA Masami (Fukuyama City University), GOTO-AZUMA Kumiko (NIPR / SOKENDAI), HASUMI Hiroyasu(The University of Tokyo), HIYAMA Tetsuya (Research Institute for Humanity and Nature, Nagoya University), IGARASHI
Tamotsu (Remote Sensing Technology Center of Japan), KANDA Hiroshi (NIPR), KIKUCHI Takashi (JAMSTEC), , MATSUURA
Yojiro (Forestry and Forest Products Research Institute), NAKAMURA Takuji (NIPR / SOKENDAI), NAKATSUBO Takayuki(Hiroshima University), NOZAWA Toru (National Institute for Environmental Studies, Japan), OHATA Tetsuo (JAMSTEC /NIPR), OHSHIMA Kay I. (Hokkaido University)., SAITOH Sei-Ichi (Hokkaido University), SHIMADA Koji (Tokyo University ofMarine Science and Technology), SUGIMOTO Atsuko (Hokkaido University), SUGIYAMA Shin (Hokkaido University),
TANAKA L. Hiroshi (University of Tsukuba) YABUKI Hironori (JAMSTEC / NIPR), YAMAGUCHI Hajime (The University ofTokyo), YAMANOUCHI Takashi (NIPR / SOKENDAI)・The 2nd term (Whereabouts in their term of office Since June, 2013)
ABE-OUCHI Ayako (The University of Tokyo), AOKI Teruo (Meteorological Research Institute), ENOMOTO Hiroyuki (NIPR /SOKENDAI), FUKAMACHI Yasushi (Hokkaido University), FUKUDA Masami (Fukuyama City University), GOTO-AZUMA
Kumiko (NIPR / SOKENDAI), HASUMI Hiroyasu (The University of Tokyo), HIYAMA Tetsuya (Nagoya University), HORI
Masahiro (Japan Aerospace Exploration Agency), MATSUURA Yojiro (Forestry and Forest Products Research Institute),
NAKAMURA Hisashi (The University of Tokyo), NAKAMURA Takuji (NIPR / SOKENDAI), NAKATSUBO Takayuki(Hiroshima University), NOZAWA Toru (Okayama University, National Institute for Environmental Studies, Japan), OHATA
Tetsuo (JAMSTEC / NIPR), SAITOH Sei-Ichi (Hokkaido University), SHIMADA Koji (Tokyo University of Marine Science andTechnology), SUGIMOTO Atsuko (Hokkaido University), SUGIYAMA Shin (Hokkaido University), TANAKA L. Hiroshi(University of Tsukuba), YABUKI Hironori (JAMSTEC / NIPR), YAMAGUCHI Hajime (The University of Tokyo),
YAMANOUCHI Takashi (NIPR / SOKENDAI)*JAMSTEC: Japan Agency for Marine-Earth Science and Technology*NIPR: National Institute of Polar Research*SOKENDAI: SOUKENDAI (The Graduate University for Advanced Studies)

187

Long-term Plan for Arctic Environmental Research
Japan Consortium for Arctic Environmental Research, JCAR
Published in April 2015
Revised in February 2016
Original Japanese version was published in September 2014,
Revised in March 2015

Contact: JCAR Office10-3 Midori-cho, Tachikawa-shi, Tokyo 190-8518 Japan
National Institute of Polar ResearchE-mail: jcar-office@nipr.ac.jp
Website: http://www.jcar.org/

188

北極環境研究の長期構想

北極環境研究の長期構想

二〇一四年九月
北極環境研究コンソーシアム

北 極 環 境研 究コ ン ソ ーシ アム (JCAR)2014 年 9 月