Warming amplification in the Arctic and its global impact

The key to Arctic climate change is Arctic warming amplification (AA). AA leads to the change
in sea ice extent and then to the realization of the Arctic sea routes. It also affects the global climate, such as atmospheric circulation, cryosphere, and the carbon cycle.
Moreover, AA will alter marine chemical components and the living environment for plankton, and hence have impacts on the major fish species and fisheries. AA will also
influence the mid-latitude weather and climate, and bring cold and heavy snow to Japan in winter.

trial biological activity will alter the amount of atmospheric carbon
dioxide absorption by vegetation, and will affect global warming
as feedback. Although it is far away from Japan, we cannot turn ablind eye to Arctic climate change, since we are affected by it, too.
In order to grasp these abrupt changes in the Arctic, to understand the mechanism, and to contribute to future climate change
projection, we conducted the Green Network of Excellence Program(GRENE) Arctic Climate Change Research Project “Rapid Changeof the Arctic Climate System and its Global Influences” for five
years between 2011 and 2016. 39 institutes all over Japan have participated in the project, and more than 360 Japanese scientists tack-1 Mechanism of warming amplification in the Arctic

led all aspects of the Arctic climate system. Comprehensive Arctic
research incorporating multidisciplinary work and collaborations
between observation and modeling have been realized.
Here we will report the scientific results achieved. In the project, four strategic research targets were presented and the outcomesfor each target are described on the following pages. Finally, themutual relationships between each target and a synthesis of “Rapid
Change of the Arctic Climate System and its Global Influences” areshown in the flow diagram on the back page.

Warming amplification in the Arctic

Surface albedo
Heattransport

2 Arctic system for

global climate andfuture changeBlackcarbonCloud

Glaciermicroorganisms

4 Projection of sea ice
Snow

distribution and Arctic
sea routes

Sea ice• Change of sea ice
distribution andrafting effect• Intensification of
atmospheric circulation• Change of heattransport
Increase of extreme events• Change of thermohaline
circulation andheat budget• Reduction ofocean circulation• Influence on mid-latitude• Change of snow area
• Sea level rise by glacierand ice-sheet melting

Stratosphere–Stratosphere
Troposphere interaction• Change of carbon cycle• Cold wave and heavy
snow in Japan• Change of primary
species of fish

• Change of CO2 sink

3 a Impacts on weather

3 b Impacts on marine

in Japan

GRENE Arctic Climate Change Research Project

The Arctic, the fastest-warming place on
What is happening now in the Arctic, under global warming?
In warming due to anthropogenic increases in carbon dioxideconcentration, the surface temperature in the Arctic is increasing
with a speed that is more than double the global average. We callthis “Arctic warming amplification,” and an understanding of its
mechanism is urgently needed.
Reduction of sea ice extent in the Arctic Ocean is continuing,
and an abrupt decrease since the 2000s is especially noticeable.
Owing to this change, potential for regular ship navigation throughthe Arctic Ocean have increased, and they have become broadly
known as “Arctic sea routes.” The reduction of the sea ice extent• Projection of sea ice
extent and Arctic sea
routesecosystem and fisheries

Map of GRENE-Arctic observation activities
Retreating Suntar-Khayata
Mountain Glacier in Siberia
region

15°W

30°W

60°W

75°W

Atmosphere
105°W

Cryosphere
Greenhouse gas
Marine ecosystem

Churchill

Sea Ice and ocean environment
Snow survey lines

Ice-albedo
feedback

30°E

Snow

Cloud-sea ice
interaction

Ice-sheet

Hiiumaa
Helsinki
Hyyti ä l ä
Kaarina
Sodankyla
Kevo
NurmesLSSL

Saaremaa

Fort Smith

QaanaaqNy-Ålesund120°W

Solid-lines (yellow, orange, pink, blue): Ship

Norman Wells
Inuvik

45°E

135°W

Prudhoe Bay

Black carbon

Degrading undergroundice (yedoma) in the permafrost zone of the North
Slope, Alaska(Courtesy of Masao Uchida, National
Institute for Environmental Studies; GoIwahana, International Arctic ResearchCenter)

Ship

Icebreakers’
observation area

Impact onmarine ecosystem

Poker Flat
Barrow
Fairbanks

Anchorage

60°E

150°W

MIRAI MR15-03
Tiksi

MIRAI MR13-06

Yakutsk

MIRAI
Oymyakon
MR12-E03
Glaciers in Suntar-Khayata region

HAKUHO MARU

Arctic Climate Change Research Project:
Rapid Change of the Arctic Climate System
and its Global Influences“Green Network of Excellence” (GRENE)
Program by Ministry of Education, Culture,Sports, Science & Technology, Japan (MEXT)
Core Institute: National Institute of Polar
Research

Period: July 2011—March 2016

S.W.L

Mirny75°E

About the project

Associated Institute: Japan Agency for
Marine-Earth Science and Technology

MIRAI MR14-05

Chokurdakh

Tura

Ocean-sea ice
interaction

Permafrost survey lines
Airliner

Fort Providence

Vario

Sea ice

1.5

Average in the Arctic(north of 60°N)

1.0

Tropospheric circulation
0.5

0.9°C

0.0

2.0°C

Global average

10

Terrestrial ecosystem

15°E

Cloud(from the data of UK Met. Office)185090°W(Photo by Hiroyuki Enomoto, National
Institute of Polar Research)

Warming amplificationin the Arctic

Stratospheric circulation

Surface air temperature change-0.545°W

Sea ice area (106 km2)

Atmospheric heating0°

1900

1950

2050

Simulation(AR5, RCP4.5)

Simulation(AR4, SRES A1B)

90°E

180°

0(Upper) The mean surface
air temperature in theArctic has clearly increased
twice as rapidly as that of
the global mean, both in
the last 100 years and in thelast 40 years.
(Lower) The Arctic sea ice
extent in September has
decreased faster than what
has been simulated by climate models. Moreover,the decrease is projected tocontinue through the 21stcentury.

Snow

105°E

120°E

135°E

150°E

165°E

Front cover: Meltwater stream over a glacier surface
darkened by glacier microorganisms in Greenland(Photo by Shin Sugiyama, Hokkaido Univ.)

CH4GlacierTundraBoreal forest(Permafrost)

Inter-university Research Institute Corporation
Research Organization of Information and Systems
National Institute of Polar Research
10-3 Midori-cho, Tachikawa-shi,
Tokyo 190-8518, Japan
Telephone: +81-42-512-0922
http://www.nipr.ac.jp
August 31, 2016

Ice-albedo
feedback

Change of sea ice area in September (from the IPCC reports)

For further details: Final Report of GRENE
Arctic Climate Change Research Project(Japanese edition only)

IssuedCO22Editing/Publication

Marine ecosystem

Impact of theArctic warmingon the mid latitude4

http://www.nipr.ac.jp/grene/165°W

2100

Observation

86

2000

OSHORO MARU

Ocean circulationand the warming of the ocean are expected to lead to changes not
only in the physical and chemical ocean environment, but also tochanges of marine ecosystems.
Looking at the land area, many glaciers distributed around theArctic are retreating. The Greenland ice sheet, the largest ice massin the northern hemisphere, is also melting markedly, and the flowout or collapse from its terminal glacier is serious. This will be aconcern in terms of the world sea level rise. Moreover, the durationof the snow season is decreasing. In such ways, snow and ice havebeen showing great changes, and thus great impacts on atmosphericcirculation and terrestrial biology are foreseen. Changes in terres-Summary of outcomes, 2011–2016
2.0• Ocean acidification• Change of primaryproduction• Stratosphere-troposphereinteraction• Change of atmos. circulation

Arctic Climate Change
Research Project
Rapid Change of the Arctic Climate
System and its Global Influences

Surface air temperature change
since the beginning of the 20th century (°C)

Earth!

JapanArctic change is advancing withpotential global influence.

Quantification of relative contribution to Arctic
warming amplification factors and their seasonality.

tent may lead to extreme events such as
heavy snowfall in mid-latitude regions
due to changes in the atmospheric circulation pattern. These may also affect theArctic and sub-Arctic ecosystems, resulting in changes in the CO2 budget.

Atmospheric CO2Land

Ocean

CO2CO2

By analyzing future climate change projection datasets simulated by a number of climate models from the Coupled Model
Intercomparison Project Phase 5 (CMIP5), we quantify the roleof various factors contributing to the Arctic warming amplification and clarify their seasonality.
Increases in surface air temperature over the Arctic regions
are smallest in summer but largest in winter. Over the Arctic
Ocean in summer, ice-albedo feedback due to sea ice retreat has
the largest tendency to warm the surface. However, the surface
warming is smallest because of the large heat uptake by the open
ocean. In autumn and winter, the heat stored in the Arctic Oceanin summer is released into the atmosphere. Moreover, there are anumber of other factors that contribute to warming the surface:strong vertical stability in the atmosphere traps warming close tothe surface; increased low-level clouds enhance the greenhouseeffect by trapping more longwave radiation; surface warming
sensitivity is larger in colder regions than in warmer regions dueto the effect of the Stefan-Boltzmann law; and so on. As a consequence, the largest surface warming occurs in winter. Over theArctic land, the ice-albedo feedback has a peak in the early sum-(Period: 1982-2013, excl. 1994, 1995)

Warming at surface

Ocean
Sea ice melt and temperature rise

Warmingin absorbed
JUN-JUL Increase
sunlight due to retreat ofSummer

Relaxation of warmingin ocean heat
AUG-SEP Increasestoragesea ice and exposure ofsea surface

release from theNOV-JAN Heat
ocean to the atmosphere.
Trapping of heat near thesurface, increase in cloud, etc.

15

10

Seasonal cycle of surface warming
Others(trapping of heat, increase in cloud, etc.)

5Ocean heat uptake and release

Heating by ice-albedo feedback due
to sea ice reduction

0-5

JANFEBMARAPR

MayJUN

JUL

AUG

SEP

OCT

NOV

4

Projection of sea ice distribution and Arctic sea routes

The Arctic sea routes:
Feasible for sustainable use.
We have proposed empirical method toestimate timing of disappearance of sea
ice, and proposed a simple model using
just sea ice motion to evaluate volumetransportation of upper ocean circulation,so called “Beaufort Gyre”, that delivers theheat into the central Arctic Ocean and affects fate of sea ice. Analyses using in-situ
and satellite observation data have clarified
that volume transportation of the oceanic
Beaufort Gyre is determined by past sea
ice motion from about four years previously. We have also constructed methods
to derive the timing of the disappearanceof sea ice associated with rafting of sea

ice from satellite-derived high-accuracy
sea ice motion data. We also conducted astudy using a high-resolution numerical
Arctic Ocean model to reveal the structure of the heat transport system from theAtlantic to the Arctic, and the impact of
meso-scale eddies on the advance/retreatof sea ice cover.
Another important theme of ours isseasonal-scale sea ice prediction, which
is necessary for a decision of whether
or not to take the Arctic route. We have
improved the statistical method of theprediction using satellite remote-sensing
data. In 2015, our prediction provided aDEC

good forecast of the timing of summer
ice retreat and the spatial pattern of theminimum ice cover. Our activity regarding the Arctic sea route included manyother themes, such as the optimal routingof ships, engineering studies on ship/iceinteraction, ship icing, economic evaluations, and a proposal of scenarios for theuse of Arctic sea routes. With these multidisciplinary efforts, studies for realizing
the sustainable use of Arctic sea routes
have advanced greatly during the GRENE
Arctic Research Project.

0°2015/09/11

-30°

30°

Arctic–mid-latitude climate linkage refers to possible impactsof Arctic climate change on mid-latitude climate and weather,which have recently been intensively studied. Severe weather in
the northern mid-latitudes is often associated with meandering
jet stream and the negative phase of the Arctic Oscillation (AO).
Both observations and model simulations provide evidence that
reductions in Arctic sea ice, or an increase in the Eurasian snow
cover, tend to cause a negative AO phase, which is often precededby weakening of the stratospheric polar vortex. This evidence hints

Changes in snow cover duration during
the past 30 years. The red area indicates
shortening of the snow-covered period,
while the blue area indicates lengthening. There has been a significant reduction of snow cover duration in Europe.

Polar vortex

3 b Evaluation of the impacts of Arctic change on marine ecosystems and fisheries

The Arctic Ocean has experienced significant warming, freshening, and ocean acidification mainly caused by rapid reductionof sea ice. In the project Ecosystem Studies on the Arctic Ocean
with Declining Sea Ice (ECOARCS), we investigated the impactof sea ice decreases on marine ecosystems. Our results show several forms of scientific evidence for changes in the marine ecosystem: the dominance of larger phytoplankton due to faster sea
ice retreat in spring in the shelf region of the Arctic Ocean andBering Sea; and a northward shift in the geographic distributionof the zooplankton community, benthos, fish, and marine mammals. On the other hand, we found that the North Pacific speciesof zooplankton transported into the Chukchi Sea (Arctic Ocean)is unlikely to establish stable Arctic populations in the near future due to large differences in geographic and life conditions.

Currently, a bloom of phytoplankton at the ice edge in spring tosummer sinks down to the seafloor and becomes food for thebenthos (Pelagic-Benthic scheme, Figure below left). However,warming due to faster sea ice retreat may increase the populationof zooplankton and fish, which feed on phytoplankton at the iceedge (Pelagic-Pelagic scheme, Figure below right).
The Arctic region will warm more rapidly than the global
mean, and the resultant changes in Arctic environments could
serve as an indication of global climate change, and should ring
alarm bells not only for scientists, but also for the public. That
is why we need to continue to monitor Arctic environmental
changes and responses of marine ecosystems to assess how they
can or cannot adapt to these changes.

Pelagic-Benthic scheme

Pelagic-Pelagic scheme

RussiaNegative AO

Stronger Siberian High

AlaskaMechanism of the impacts of Arctic change on weather and climate in Japan

Fallen tree by a snowstorm (Photo by Shuhei Takahashi, Okhotsk Sea Ice Museum of Hokkaido)

-90°
0°

-15-180°
Sea Ice Thickness [m]0Predicted (green line, forecasted at the end of May) and observed (white area) ice area
on September 11, 2015

Zooplankton

Benthos Feeders

150°Plankton & Fish Eaters
Benthos

CanadaEast Siberian Sea

Phytoplankton

Meandering jet stream

0°Laptev Sea-12

Changes and shifts in the Arctic marine
ecosystem have been evident.

Cold in Euro-Atlantic
regionJet stream

Cold in Siberia
and Far Eastat a stratospheric involvement in the Arctic–mid-latitude climate
linkage. By artificially suppressing the stratospheric wave–meanflow interactions in numerical experiments, tropospheric signalsof the Arctic–mid-latitude climate linkage can be significantly
reduced, and thus we confirm that the stratosphere plays a crucial role in the Arctic–mid-latitude linkage. The results also imply that realistic representations of both Arctic surface boundary
conditions and stratospheric processes are critical for improving
predictions of weather and climate in the mid-latitudes.

Strategic Research Targets

0°-58.4 -38.9 -19.5 0.0 19.5 38.9 58.4 77.9 97.3
Trend of Snow Cover Duration [Day/30 years]

Sea iceand snow

Strategic Research Targets

12Production increased
Decreased

Trends of tree productionin the second half of the20th century inferred fromtree ring analyses

Lengthening

Cloud

High sensitivity
to the temperature
increase60

3 a Evaluation of the impacts of Arctic change on weather and climate in Japan

Decelerated
polar vortex

Shortening

Sunlight
Sea iceand snow

Inhibition ofconvention

GreenhouseeffectThe seasonal cycle of warming amplification over the Arctic Ocean and its contributing factors. The black line shows the seasonal cycle of temperature increases from the endof the 20th century to the end of the 21st century averaged over the Arctic Ocean under the moderate warming scenario of RCP4.5. The contributions from the major factors
contributing to the Arctic amplification are shown by the colored lines (red, blue and green).

Climate change in the Arctic brings
cold spells and snowstorms over Japan.

Image of CO2 exchange
in the Arctic(Photo by Yoshimi Tsukagawa, National Institute of Polar Research)Ice-albedo feedback:As the temperature rises over the Arctic, snow and ice with high reflectance retreat, and the land and the ocean surfaces with low reflectance are exposed. The
absorption of sunlight then increases, leading to a further increase in temperature and hence to a further increase in snow and ice retreat.

On-warming°

Strategic Research Targets

Snow sampling site near Denali National Park, Alaska

mer. Its additional heat warms the land surface, though part ofthis enhances surface evaporation and reduces surface warming.
In winter, on the other hand, the land has no heat storage to release into the atmosphere. Therefore, the amplitude of seasonalvariation for surface warming is smaller over the Arctic land thanover the Arctic Ocean.
This study clarifies the seasonality and the relative contributions of various factors that were separately investigated, and also
provides a comprehensive understanding of the mechanism ofArctic warming amplification.

Pre-warming°

Present

End of 21st century

CO2 emission CO2 uptake
from the soil by vegetation

Understanding the mechanism of warming amplification in the Arctic90°

by ecosystem model simulations, whichsuggests that CO2 uptake by the Arctic
may not continue in the future.
The GRENE-Arctic project has also
revealed that snow duration is getting
shorter and that reduction of sea ice ex-1-60The land and ocean in the Arctic have an
important role in the uptake of CO2 fromthe atmosphere, which has been demonstrated by observations of atmospheric
CO2 concentration. An increase in terrestrial uptake for the most recent 10 years
was also suggested by the observed data.
Net uptake (or release) of CO2 by theland is a balance between net primary
production of vegetation and soil respiration. It had been generally believed thatthe productivity of vegetation in cold regions such as the Arctic and sub-Arctic
increased with warming. However, treering analyses for circum-arctic forest ecosystems revealed that not all regions in theArctic and sub-Arctic show increases intree growth. Tree growth is decreasing insome regions such as eastern Siberia, theAlaska Interior, and Canada. Moreover,soil respiration is expected to increase
with temperature, which has been shown

Strategic Research Targets

Temperature change from the end of 20th century to the end of 21st century (°C)

Understanding the Arctic system for global climate and future change

Stratosphere

2Troposphere

Strategic Research Targets

Icebreaker navigating thethin ice area(Photo by Kazutaka Tateyama, Kitami
Institute of Technology)

0.25

0.5

0.75

1An example of optimal routing based on the predicted sea ice thickness on 24 October, 2011 with the prediction system for Arctic searoutes