2010 PAGES Regional Workshop in Japan
Program and Abstracts

Noyori Memorial Conference Hall, Nagoya University, JAPAN
June 5 – 6, 2010

Co-organized by:
Nagoya University Global COE “From earth system science to basic andclinical environmental studies”
Co-supported by:
Japan Drilling Earth Science Consortium
Hosted by:
Graduate School of Environmental Studies, Nagoya University
Hydrospheric Atmospheric Research Center, Nagoya Universityii

Program
2010 PAGES Regional Workshop in Japan<Schedule> June 5 (Sat) - June 6 (Sun), 2010
<Venue>Noyori Memorial Conference Hall (1st Floor, Large MeetingRoom), Nagoya University, JapanDay 1: June 5, Saturday
09:30-09:40 Local Organizing Committee
Opening Remarks
09:40-09:50
Tetsuzo YASUNARI (GCOE Leader)
Introduction of Nagoya University GCOE program
09:50-10:10 Thorsten KIEFER (PAGES IPO Executive Director)
Introduction of PAGES and Aims of this regional workshop<<Session on PAGES Focus 4>>
Chair: Hikaru TAKAHARA (Kyoto Prefectural University)
10:10-10:35

John DEARING (University of Southampton, UK）

Keynote on PAGES Focus 4 (Human-climate-ecosystem interactions)
10:35-11:00

Coffee Break & Poster Session

11:00-11:25
Tetsuzo YASUNARI (Nagoya University)
Changes in the Asian monsoon climate during 1700-1850 induced bypreindustrial cultivation
11:25-11:50 Takakazu YUMOTO (Research Institute of Humanity and Nature)
Human-nature interaction and climate in the Japanese Archipelago
11:50-13:15

Lunch Break & Poster Session1

<<Session on PAGES Focus 2 & CCT 2 (Part 1)>>Chair: Tatsuhiko SAKAMOTO (JAMSTEC)
13:15-13:40

Heinz WANNER (Univeristy of Bern, Switzerland)

Keynote on PAGES Focus 2 (Regional Climate Dynamics)
13:40-14:05
Hodaka KAWAHATA (University of Tokyo)
One result from IMAGES and the relevant studies in Japan – the relationshipbetween environmental change and human activity during the mid-Holocene inJapan 14:05-14:30
Koji FUJITA (Nagoya University)
Recent changes in Himalayan glaciers and ice core studies in the Asian
highland
14:30-15:15

Coffee Break & Poster Session<<Session on PAGES Focus 2 & CCT 2 (Part 2)>>Chair: Yasufumi IRYU (Nagoya University)

15:15-15:40

Fatima ABRANTES (National Laboratory of Energy and Geology,
Portugal)

Keynote on PAGES Cross-Cutting Theme 2 (Proxy Development,
Calibration and Validation)
15:40-16:05
Atsushi SUZUKI (Geological Survey of Japan, AIST)
Climate events in the earliest 20th century detected in coral records from
Ishigaki and Ogasawara Islands, Japan.
16:05-16:30
Takeshi NAKATSUKA (Nagoya University)
Spatial and temporal reconstructions of past Asian summer monsoon activities
using oxygen isotopic ratios of tree-ring cellulose
16:30-16:55
Masumi ZAIKI (Seikei University)
Document-based reconstruction of paleoclimate in Japan2

18:00-20:00

Reception at “Green Salon Higashiyama” in Nagoya University

Day 2: June 6, Sunday<<Session on PAGES Focus 1>>
Chair: Tomohisa IRINO (Hokkaido University)
09:00-09:40

Bette OTTO-BLIESNER (National Center for Atmospheric Research,
USA) and Cathy WHITLOCK (Montana State University, USA)

Keynote on PAGES Focus 1 (Climate forcings)
09:40-10:05 Yusuke YOKOYAMA (University of Tokyo)
Detecting Holocene sea level changes of Antarctic ice sheet
10:05-10:30
Hiroko MIYAHARA (University of Tokyo)
Historical changes in solar activity and its impact on regional-global climate.
10:30-11:00

Coffee Break & Poster Session<<Session on PAGES CCT 3>>
Chair: Akio KITOH (Meteorological Research Institute, Japan)
11:00-11:25

Bette OTTO-BLIESNER (National Center for Atmospheric Research,
USA)

Keynote on PAGES Cross-Cutting Theme 3 (Modeling)
11:25-11:50

Ayako ABE-OUCHI (University of Tokyo)

Forcing and feedbacks for the change of sea level and climate throughout theglacial-interglacial cycle: A modelling perspective in Japan.

11:50-13:00

Lunch Break & Poster Session3

<<Session on PAGES Focus 3 & CCT 1 (Part 1)>>Chair: Hajime KAYANNE (University of Tokyo)
13:00-13:25

Thorsten KIEFER (PAGES IPO Executive Director)

Keynote on PAGES Focus 3 (global earth-system dynamics)
13:25-13:50
Kenji KAWAMURA (National Institute of Polar Research)
Millennial-scale climatic changes during the last seven glacial periods:
perspective from the Dome Fuji ice core records
13:50-14:15
Ryuji TADA (University of Tokyo)
Millennial-scale Asian monsoon dynamics, its tele-connection mechanism, andpossible linkage with solar activity
14:15-14:45

Coffee Break & Poster Session<<Session on PAGES Focus 3 & CCT 1 (Part 2)>>Chair: Kotaro YAMAGATA (Joetsu University of Education)

14:45-15:10

Pierre FRANCUS (Institute of National Scientific Research, Canada),
Steve COLMAN (University of Minnesota, USA) and Chris TURNEY(University of Exeter, UK)

Keynote on PAGES Cross-Cutting Theme 1 (Chronology)
15:10-15:35 Yusuke OKAZAKI (JAMSTEC)
Ocean circulation in the North Pacific during the last glacial termination
15:35-16:00
Naomi HARADA (JAMSTEC)
Large-scale blooms of Emiliania huxleyi in the Bering Sea during the past 100
years and its implication of recent global biogeochemical changes
16:00-17:00

Overall discussion

17:00-17:15
Local Organizing Committee
Closing Remarks

4List of Posters
Ishiwatari R., N. Fujino, D. Brincat, S. Yamamoto, H. Takahara, K. Shichi, S. K.
Krivonogov
A 35 kys record of organic matter composition and δ13C of n-alkanes in bog
sediments close to Lake Baikal: Implications for the paleoenvironmental study
Yamamoto S., J. Kitano, Y. Tomiyama, R. Ishiwatari, H. Uemura
Influence of human activity and natural disaster to lake sediment revealed by recordsof sedimentary organic matter
Ishiwatari R., K. Negishi, H. Yoshikawa, S. Yamamoto
Glalcial-interglacial productivity and environmental changes in Lake Biwa, Japan: A
sediment core study of organic carbon, chlorins and biomarkers
Murakami S.
Atmospheric Energetics in Glacial Climate
Kawano S., T. Irizuki, R. Nomura
Bay environmental changes with relation to the opening of the Manzeki-seto in
Tsushima Island, Southwest Japan
Sagawa Y., C. Saito, Y. Hanafusa, H. Saito
Data sites of sediment core samples collected by JAMSTEC cruises
Tomiyama T., H. Machiyama, W. Soh
JAMSTEC core samples are open to after-moratorium requests
Kitamura A., Yamamoto N., Ishimura T., Irino T., Tsunogai U.
Paleothermometer using the oxygen isotope ratio of cavernicolous micro-bivalve
Carditella iejimensis: Application to paleoceanographic reconstructions of East China
Sea during the last 7,000 years

5Nagashima K. H. Nishido, M. Kayama, S. Toyoda, Y. Igarashi, R. Tada
Provenance study of Asian dust based on cathodoluminescence analysis of single
quartz grain
Onodera J., K. Takahashi
Silicoflagellate flux and oceanographic conditions in the northern Subarctic Pacificand the southern Bering Sea, '90-94
Kamae Y., H. Ueda, A. Kitoh
Weakening of tropical atmospheric circulation in the Middle Pliocene
Yamagata K.
The influence of human-induced hydrological change on the flood plain environmentof the Amur River
Yamagata K., T. Sone
Application of tephrochronology to the glacial and periglacial environment study in
Kamchatka Peninsula, Russia
Okamoto S.
Re-evaluation of past summer temperature reconstruction by melt features in Belukha
ice cores, Siberian Altai
Sano M., B. M. Buckley, T. Sweda
Tree-ring based hydroclimate reconstruction over northern Vietnam from Fokienia
hodginsii
Yasudomi Y., Y. Motoyama, T. Oba
Marine environmental change during the last interglacial in the Northwestern Pacificbased on radiolarian assemblages
Kano A., M. Hori, C.-C. Shen
Reconsideration of climate in Japan during the last deglaciation: a stalagmite record

6Mitsuguchi T., P. X. Dang, H. Kitagawa, T. Uchida, Y. Shibata
Coral Sr/Ca and Mg/Ca records from 1948 through 1999 in Con Dao Island, Vietnam:
Monitoring of ENSO and East Asian monsoon in the South China Sea
Mitsuguchi T., P. X. Dang, H. Kitagawa, Y. Shibata
Seawater 14C time series of AD 1948-1999 in the tropical South China Sea:
Reconstruction from coral annual bands
Mitsuguchi T., E. Matsumoto, T. Uchida, P. J. Isdale, T. Kawana, H. Kan
Early mid-Holocene sea-surface temperature in the Ryukyu Islands: Reconstruction
from coral Mg/Ca and Sr/Ca ratios
Kawakubo Y., Y. Yokoyama, A. Suzuki, Chantal Alibert, Steve Eggins
A 423-year-long paleoceanography recorded in Porites coral in Kikai Island,Southern Japan
Obrochta S., Yokoyama Y., S. Sakai, K. Kimoto, M. Inoue, K. Ohkushi, H.
Amakawa, H. Kawahata
Holocene to last glacial ITF variability
Yamane M., Y. Yokoyama
East Antarctic Ice Sheet fluctuations and global climate changes during the last 5Myr
Kubota K., Y. Yokoyama, S. Sakai, H. Matsuzaki, T. Toyohuku, K. Iijima, T.i
Osada, P. Ajithprasad, S. K. Bhattacharya
Mid Holocene climate reconstruction using oxygen isotopic composition of modern
and fossil catfish otolith (Ariopsis spp.) in North West India and its relation to Indus
civilization.
Nakamura A., Y. Yokoyama, H. Maemoku, H. Yagi, M. Okamura, H. Matsuoka, N.
Miyake, T. Osada, H. Teramura, T.i Yamada, D. . Adhikari, V. Dangol, H.
Matsuzaki
Holocene variability of the Asian monsoon inferred from a sediment core obtained
from Lake Rara, western Nepal

7

Sawada K., T. Sawai, O. Seki
Transport and diagenesis of higher plant terpenoids in soil, peat and lacustrine
sediment from northern Hokkaido
Asami, R., Felis, T., Deschamps, P., Hanawa, K., Iryu, Y., Bard, E., Durand, N. and
Murayama, M.
Evidence for tropical South Pacific climate change during the Younger Dryas and the
Bølling-Allerød from geochemical records of fossil Tahiti corals.
Morimoto M., O. Abe, K. Yamada, N. Yoshida, P. Ghosh
Estimation of allogenic and authigenic carbonates in sediments from Lake Hovsgol,
Mongolia using multi isotopes
Qiang Li, Takeshi Nakatsuka, Kimitaka Kawamura, Yu Liu
Hydroclimatic variation detected by tree-ring cellulose δ18O in North China since
A.D. 1675
Hongo C., H. Kayanne
Spatial and temporal variations of coral species diversity in the Pacific during the past
10,000 years
Nakamura N., H. Kayanne, H. Iijima, T. R. McClanahan, S. K. Behera, T.
Yamagata
Mode shift in the Indian Ocean through 20th century Recorded in Kenyan Coral
Iijima H., H. Kayanne, N. Nakamura
Past 100 years inter-annual sea surface salinity changes in the Western Pacific basedon coral isotope analysis
Ogawa N.O. , N. Ohkouchi, Y. Chikaraishi
Trophic level vs. eutrophication: A case study in Lake Biwa with nitrogen isotopic
compositions of amino acids
Saito K., S. Marchenko, V. Romanovsky, N. Bigelow, K. Yoshikawa, J. Walsh
Thermally-conditioned paleo-permafrost variations from global climate modeling8Hayashi R.
Millennial-scale vegatation response to the East Asian monsoon for the last 40,000
years based on a pollen record of Lake Biwa, the central Japan
Irino T.
Past seasonal variability of the Japan Sea surface water deduced from bivalve shells
Watanabe Y., H. Matsuoka, S. Sakai, M. Yamada, S. Ohsawa, M. Kiguchi, T.
Satomura, S. Nakai, B. Brahmantyo, K. A. Maryunani, T. Tagami, K. Takemura, S.
Yoden
Paleoclimatological study using stalagmites from Java Island, Indonesia
Abe, O.
Clumped isotopes in coral skeletons
Seto K., D. L .Dettman, H. Takata, S. Kishiba, T. Sato
Paleoenvironmental change in a coastal lagoon during the past 2000 years as recordedin the sediment of Lake Nakaumi, Southwest Japan
Sasaki N., Takahara H., and Kishimoto G.
Fire and human impacts on vegetation changes during the Holocene in the Kyoto
basin, Japan
Nomura R.
Decadal changes in response to human activities and sea-level change in the 20th
Japanese lagoons: Foraminiferal evidence
O'hishi, R and Abe-Ouchi, A
Polar amplification in the mid-Holocene derived from dynamical vegetation change
Yoshimori, M and Abe-Ouchi, A.
Application of climate feedback analysis to paleoclimate modelling
Chikamoto, M. O, A. Abe-Ouchi, A. Oka, and R. OhgaitoInteraction between ocean circulation and sea-ice coverage controlling the marine
carbon cycle

9Nakamura T., Hoshino M., Tanaka T., Yoshida H., Saito T., Tsukada K.,
Katsurada Y.
Possibilities of human migration from river flood plain to highland area at around2000 cal BC: 14C ages of remains from archeological sites in the Bishri Region,
Middle Euphrates, Syria
Tsugeki N. K., Urabe J., Hayami Y., Kuwae M., and Nakanishi M.
Phytoplankton dynamics in Lake Biwa during the 20th century: Complex responses
to changes in nutrient status and climate variation

10

Abstracts

12

Session on PAGES Focus 4

Focus 4: Past Human-Climate-Ecosystem
Interactions (PHAROS)
This Focus addresses the long-term interactions among past climate conditions,
ecological processes and human activities during the Holocene. Emphasis lies incomparingregional-scalereconstructionsofenvironmental

andclimatic

processes using natural archives, documentary and instrumental data, withevidence of past human activity obtained from historical, paleoecological andarchaeological records. The Focus promotes regional integration of records anddynamic

modeling

to:(1)

understandbetterthenatureofclimate-human-ecosystem interactions; (2) quantify the roles of different naturaland anthropogenic drivers in forcing environmental change; (3) examine thefeedbacks between anthropogenic activity and the natural system and; (4)provide integrated datasets for model development and data-model comparisons.

Overarching Questions:- What are the historical patterns of human interactions with climate change
and ecological processes?
- How can we learn from these past patterns and interactions in order tobetter understand and manage natural ecosystems at present and in the
future?

Focus Goals•

To understand and quantify the nature of human activities that haveinfluenced the functioning of ecological systems. For example, the historic
links between climate, human activities (such as irrigation practices) and soil
erosion in different world regions.

•

To elucidate feedbacks from human activities to the climate system. For
example, determining the impact (local to global) of deforestation on climate.

•

To describe how human and climate impacts have interacted with internal
system dynamics. For example, the extent to which river channel changes area consequence of external forces, such as land use and climate, or internal
forces, such as hydraulic dynamics and system configuration.

13

Session on PAGES Focus 4•

To explore the sensitivity and resilience of modern ecological systems to new
or increased stresses from human activities and climate change. For example,
to identify those ecological processes that have been the most responsive topast rapid climate change and which may be sensitive to projected climatechange in the future.

•

To synthesize and integrate findings on past human-climate-ecosysteminteractions in order to help develop appropriate sustainable management
strategies. For example, determining the historical range of variability innatural disturbance regimes, the reference conditions that are most relevant
for ecosystem restoration or the land use that appears most appropriate in theface of projected change.

14

Session on PAGES Focus 4

Changes in the Asian monsoon climate during 1700 -1850 induced bypreindustrial cultivation
Tetsuzo Yasunari*,
Kumiko Tanaka, and Kazuyuki. Saito* Hydrospheric Atmospheric Research Center, Nagoya University
Preindustrial changes in the Asian summer monsoon climate from the 1700s to the1850s were estimated with an atmospheric general circulation model (AGCM) using
historical global land cover/use change data reconstructed for the last 300 years.
Extended cultivation resulted in a decrease in monsoon rainfall over the Indian
subcontinent and southeastern China and an associated weakening of the Asian summer
monsoon circulation. The precipitation decrease in India was marked and was consistent
with the observational changes derived from examining the Himalayan ice cores for the
concurrent period. Between the 1700s and the 1850s, the anthropogenic increases ingreenhouse gases and aerosols were still minor; also, no long-term trends in natural
climate variations, such as those caused by the ocean, solar activity, or volcanoes, werereported. Thus, we propose that the land cover / use change was the major source ofdisturbances to the climate during that period. This report will set forward quantitative
examination of the actual impacts of land cover/use changes on Asian monsoons,relative to the impact of greenhouse gases and aerosols, viewed in the context of global
warming on the interannual, decadal, and centennial time scales.

15Session on PAGES Focus 4

Human-nature interaction and climate in the Japanese Archipelago
Takakazu YumotoResearch Institute for Humanity and Nature
The Japanese Archipelago extends over 3000 km from North to South, andincludes subarctic, cool temperate, warm temperate and subtropical climatic zones. It isevident that, even during the global environmental changes that have taken place overthe past 100.000 years, these various climatic zones were present. As a result, thecharacteristics of the natural environment and the human subsistence activities within
the Japanese Archipelago varied greatly, as did the relationships between nature andhuman activity. Under the influence of climatic change and human activities, thedistributions of individual species of plants and animals in the Japanese Archipelago
and its surrounding landmasses have been constantly changing. Populations of plants
and animals have repeatedly divided, expanded and diminished in response to changes
in the availability of suitable habitat. Where suitable habitat was not available, thespecies became extinct.
The knowledge and skills that humans have developed concerning individual
species can be considered to contain both the idea that biological resources should be
used in sustainable way, and the desire to harvest without fear of exhausting theresources. Although ethnological research has highlighted phenomena such as publicmanagement of lands and resources, and environmental preservation through limited
harvest, it is still unclear when, in which region and among whom the philosophy ofpreservation was put into practice, or under which social conditions it became an
influential way of thinking. Throughout the period of human habitation, the JapaneseArchipelago has been blessed with a warm climate and abundant rainfall, andconsequently abundant biological resources. But what is the history of overuse andexhaustion of those resources? And how did individual species fare in this historical
process? This presentation will show our tentative results on these issues, based on the
results of a trans-disciplinary project “A New Cultural and Historical Exploration into
Human-Nature Relationships in the Japanese Archipelago”.

16

Session on PAGES Focus 2 & CCT 2

Focus 2: Regional Climate Dynamics
This Focus seeks to achieve a better understanding of past regional climatic andenvironmental dynamics through comparison of reconstructions and model
simulations. Activities contribute towards a global coverage of high-resolution,
well-dated paleoclimatic data, reconstructions of past climate-state parameters(e.g., temperature, precipitation, atmospheric pressure fields), a better
understanding of past modes of climate variability and their teleconnections, andof rapid and extreme climate events at the regional scale. The Focus hosts
activities that promote data-model comparisons and collaborates closely with
Cross-Cutting Theme 2 on proxy development and calibration. The timescales
covered by this Focus encompass the last 130 ka, in particular the time streams of
the last glacial-interglacial cycle, the Holocene, and the last 2 ka.

Overarching Questions- How have regional climate and the Earth’s natural environment changed in
the past?
- What are the main patterns and modes of climate variability on
sub-decadal to orbital timescales?
- How do climate variability and extreme events relate to the mean state of
the climate system?

Focus Goals- Develop datasets that describe the patterns of past climate change andclimate variability at the regional scale, including the major climate statevariables, such as air pressure, temperature, precipitation or precipitation
minus evaporation (P-E) and atmospheric and oceanic circulation patterns,
for the last 2 ka and wherever possible during the last glacial cycle (last
130 ka).
- Examine the regional response of marine and terrestrial ecosystems tolarge-scale changes in the climate system. Activities towards this goal arecoordinated with Focus 4 and offer links with the DIVERSITAS program.
- Better understand the mechanisms (natural and anthropogenic forcing,internal variability, feedbacks, sensitivity) operating in the climate systemthat determined regional variations, including abrupt and extreme climate

17

Session on PAGES Focus 2 & CCT 2

events, of climate and environment over the past 130 ka.
- Understand the modes of variability, such as ENSO/PDO, NAO/AMO, theteleconnections between them, and their influence on regional climate
history.
- Carry out ensemble simulations of past climate variability with suitableclimate models of different complexity, in close coordination with thereconstruction activities and with Focus 1 and CCT 3.
- Support improvements in model development and data-model comparison
approaches to better constrain the drivers and mechanisms of regional
climate change on different timescales.

18Session on PAGES Focus 2 & CCT 2

One result from IMAGES and the relevant studies in Japan – therelationship between environmental change and human activity during
the mid-Holocene in Japan Hodaka Kawahata
Graduate School of Frontier Sciences, The University of Tokyo
Reconstruction of the long-term response of ocean environments to various
climate changes (e.g., ENSO: El Nino/Southern Oscillation, Asian monsoon,
Glacial-Interglacial change) is an essential step for better understanding of climate
system of the Earth. We took more than ten cores under an umbrella of the IMAGES(International Marine past Global Changes Study) program in the western Pacific fromthe equatorial region to the Okhotsk Sea in 1998 and 2001 and collected relevant andadditional cores for the promotion of PAGES program. On result comes from off thenorthern part of the Japanese Island to understand the relationship between
environmental change and human activity at the Sannai-Maruyama ruin, which is themost famous ones in Japan during the mid-Holocene. We analyzed alkenone
temperature, organic carbon and nitrogen content, pollen abundance and assemblage
and other environmental parameters in the marine core collected near the ruin. The
establishment of the settlement of the people can be attributed mainly to a great increasein the food supply under warm climatic conditions, whereas the decline of thesettlement may have been determined primarily by climatic cooling (2.0 °C), whichcaused both a reduction in the terrestrial food supply and the onset of severe winters.
Synchronization of the decline of civilization between the Sannai-Maruyama and northMesopotamia and along the Yangtze River around 4.0–4.3 cal. kyr B.P. could have been
affected by regional to global scale of climatic change [Kawahata et al., 2008].
References
Kawahata, H., Yamamoto, H., Ohkuchi, K., Yokoyama, Y., Kimoto, K., Ohshima, H. andMatsuzaki, H. (2009) Changes of environments and human activity at the
Sannai-Maruyama ruins in Japan during the mid-Holocene Hypsithermal climaticinterval. Quaternary Science Reviews., 28, 964-974.

19

Session on PAGES Focus 2 & CCT 2

Recent changes in Himalayan glaciers and ice core studies in the Asian
highlandKoji Fujita
Graduate School of Environmental Studies, Nagoya University
Fate of Himalayan glaciers mentioned in the IPCC report is the recent hottest
matter of debate in climate science. The debate seems to be baseless, however, because
few observational facts have been reported so far. We have observed the changes inglaciers by ground survey in the Nepal Himalaya since the 1970s. In this presentation,
we show up-to-date results with respect to changes in Himalayan glaciers whose
wastage is accelerated in the recent decade.
We also show a short review on ice core studies in the Asian highland. In the lasttwo decades, a dozen of ice cores have been drilled from Asian glaciers. Putting timescale on ice core is still challenge to be tackled because many ice cores retrieved at theelevation lower than 6000 m a.s.l. are affected by some sort of melt. Counting dust
and/or pollen peaks is a unique method in this region while counting seasonal cycles ofchemical species is an ordinary method in the Polar Regions. It has been reported
bismuth as a marker of volcanic events and radio active isotope of lead for absolute
dating. Interpretation of water stable isotopes is more complicated the Polar Regions
because the isotopes do not simply depend on temperature in the seasonal basis,
especially under the Indian monsoon. Although some studies have asserted the water
stable isotopes as proxy of precipitation because of an ‘amount-affect’ on the isotopes,
no comparison with accumulation itself has been performed so far.
We briefly show our recents results with respect to summer temperaturereconstruction from Belukha ice cores, the Russian Alta Mts. and a drastic deglaciation
during the Bølling-Allerød period revealed by soil sample at the bottom of Grigoriev ice
core, the Kyrgyz Tienshan Mts.

20

Session on PAGES Focus 2 & CCT 2

Cross-Cutting Theme 2: Proxy Development,
Calibration and Validation
This Theme supports improvement of the precision and accuracy of paleo-proxies
as a basis for high-quality reconstructions of past global change to complement
instrumental data. It includes efforts on proxy interpretation and development,
analytical innovation, inter-laboratory comparisons, and calibration refinement,
which lead to uncertainty reduction in proxy-based reconstructions.

Goals
The overarching goal of this CCT is to support advances in the precision andaccuracy of paleo-proxies in order to generate high-quality records of past globalchange that can complement instrumental data and modeling efforts. To this end,
specific aims include improvement in proxy interpretation and development,
refinement of analysis and calibration, and encouragement/facilitation ofinter-laboratory comparisons.
To improve the quality of proxy records and the resulting reconstructions, thefollowing key objectives have been identified in the steps from site selection toreconstruction:-

Discovering

newproxies:

In

order

to

arriveatacomprehensive

reconstruction of Earth’s environmental history, it is necessary to expand theavailable range of proxies to include environmental parameters, for which wehave basically no (e.g., cloud formation,) or only poor (e.g., ocean salinity,
sea ice cover, ice sheet thickness, dimethyl sulfide (DMS)) proxies at hand.
PAGES prepares the ground for this by facilitating knowledge exchange
among researchers studying past records and those interested in modern
processes(e.g.,

biologists,

geophysicists,geochemists,

glaciologists,

oceanographers and climatologists).
-

Opitimizing site selection: Observational data (e.g., results from IGBP sisterprojects and WCRP) and model runs with simulated proxies can assist site
selection by identifying sites sensitive to environmental change and proxy21

Session on PAGES Focus 2 & CCT 2

response. PAGES provides a platform for communication with these groups
and supports campaigns to study key locations and undersampled regions.
-Improving sample analysis: Progress in the ever-increasing quality of field
and laboratory measurements usually results from innovations, often oftechnical nature, by specialist scientists. PAGES can contribute to analyticalimprovement

byorganizing

group

effortssuchasinter-laboratorycomparison/calibration studies.
-

Providing calibration datasets: The calibration of proxy data requires large
sets of samples or proxy-datasets from the (quasi-modern) calibration period,
as well as optimal datasets of instrumental measurements. Collaboration withother projects in IGBP, WCRP, and the broader ESSP community can help toidentify and provide datasets for calibration.

-

Validating proxy interpretation: A deeper understanding of the biological,
physical and chemical controls on the formation of proxies and proxy-archives,and of their post-depositional history (alteration, transport, etc.) is necessary
to reliably and quantitatively interpret the proxy data with respect to theirrepresentation of environmental and climatic parameters. To this end, PAGES
actively promotes interaction of paleo and modern and of cross-disciplinary
approaches. In addition, combination of multiple independent lines ofevidence, e.g., multi-proxy strategies and data-modeling comparisons, ispromotedasacomplementary

approachtoincreaseconfidence

inreconstructions.
-

Quantifying and expressing proxy-data uncertainties: Beyond efforts to
reduce uncertainties in general, the coherent and quantitative expression of
uncertainties is a major task within CCT2. This is addressed according to therequirements of modeling studies and in close collaboration with statisticians,
and with working groups of the Foci 1-3.

22

Session on PAGES Focus 2 & CCT 2

Climate events in the earliest 20th century detected in coral records
from Ishigaki and Ogasawara Islands, Japan.
Atsushi Suzuki
Geological Survey of Japan, National Institute of Advanced Industrial Science andTechnology (AIST)
Although knowledge of the past environments has been highly expected, there
have been only few studies conducted on ocean environment exceed a century
especially in the subtropical Northwestern Pacific due to a lack of observational data.
Recently, however, two century-long coral records have become available, one is from
Ishigaki Islands, southern Ryukyus (Mishima et al., in press) and the other is from
Ogasawara Islands (Felis et al., 2009). Coral skeletal oxygen isotope data from Ishigaki
showed a consistent profile with available sea surface temperature (SST) information
for the post-1890s. The coral-based SST reconstruction enabled investigations on therelationships with the East Asian winter Monsoon (EAWM) and El Nino Southern
Oscillation (ENSO). The Ishigaki coral record characteristically revealed the abrupt
cooling during 1900-1905. This timing was consistent with exclusively cold winter inwhich Japan’s lowest observational air temperature in 1902. It was suggested thatdevelopment of Siberian High intensified the EAWM at this period. Also, it is probablethat the cooling occurred in relation to the surface ocean freshening detected in the
Ogasawara coral record in the early-twentieth-century [Felis et al., 2009]. Aboveconsistency suggests the mutually coupled phenomenon uniquely found in the earliest
1900s in the northwestern subtropical Pacific.
References
Felis, T., A. Suzuki, H. Kuhnert, M. Dima, G. Lohmann, and H. Kawahata (2009),
Subtropical coral reveals abrupt early-twentieth-century freshening in the western
North Pacific Ocean, Geology, 37, 527-530, doi:10.1130/G25581A.1
Mishima, M., Suzuki, A., Nagao, M., Ishimura, T., Inoue, M., and Kawahata, H. Abrupt
shift toward cooler condition in the Earliest 20th Century detected in a 165-yearcoral record from Ishigaki Island, southwestern Japan. Geophysical Research
Letters, in press.

23

Session on PAGES Focus 2 & CCT 2

Spatial and temporal reconstructions of past Asian summer monsoon
activities using oxygen isotopic ratios of tree-ring cellulose
Takeshi Nakatsuka
Graduate School of Environmental Studies, Nagoya University
Tree ring is one of the most important proxies for past climate changes and has
been applied in many regions on the world and referred frequently in authorizedclimatic publications such as IPCC reports. The excellence of tree ring as paleoclimate
proxy is owing to its exact chronology, long continuity of records, wide coverage onland and endurance even after cutting or burying etc. However, the tree ring has notbeen utilized very well in Asia, especially in temperate and humid regions of South andEast Asia including Japan, until now. It is because climate does not usually control thetree growth in the temperate and humid areas and, in the densely populated Asian
forests, tree rings mainly reflect long term competition with neighboring trees rather
than climate changes.
Recent development of oxygen isotope measurements for organic matter has
provided us with a novel tool to reconstruct past climate change using oxygen isotopic
ratios of tree-ring cellulose. Because the variation in oxygen isotope ratio of tree-ringcellulose only depends on the two climatic parameters, oxygen isotope ratios ofprecipitation and relative humidity in the growing season, it can record past changes inhydroclimate independent from any ecological disturbances. So far, many long timeseries of oxygen isotope ratios have been obtained for tree-ring celluloses in Asian
countries including Japan, and it has been proved that the oxygen isotope ratio oftree-ring cellulose reflects the summer hydroclimate (precipitation amounts and relative
humidity) very well in all of the studied areas, indicating its usefulness for Asiansummer monsoon studies such as teleconnection analyses of climate dynamics andevaluations of human-ecosystem-climate interactions in humid and temperate regions.

24Session on PAGES Focus 2 & CCT 2

Document-based reconstruction of paleoclimate in Japan
Masumi Zaiki
Seikei University, Japan
Numerous studies in many parts of the world have reconstructed past climate
conditions based on instrumental and proxy data. As the official meteorologicalobservation network of the Japan Meteorological Agency was first established in the1870s, historical documents are an important type of proxy data for reconstructing theclimate of Japan before this time.
Japanese historical documents such as old diaries from individuals, clan offices
and shrines often include daily weather descriptions. Many of these weather
descriptions for the Edo Period (the 17th - 19th centuries) have been coded into a
database by Japanese climatologists and have been used to reconstruct seasonaltemperatures, the length of the rainy season (Baiu), global solar radiation, and synoptic
weather patterns. The dates of cherry blossom flowering, the freezing of lakes, and theharvesting of crops extracted from historical documents have also been used for climate
reconstruction studies.
Recently, another type of historical document—instrumental weather records—
has been recovered for several locations in Japan in the 19th century. The recovered data
extend the beginning of the instrumental series back from 1872 to 1819. These data
were converted to modern units, digitized, and homogenized to account for changes inelevation and differing observation schedules. The corrected and homogenized data
were shown to be reasonable based on homogeneity tests and comparison with modern
data. The instrumental temperature data show good agreement with the reconstructed
temperatures from the old diaries. These two types of historical documents are not only
individually useful, but are also useful for crosschecking the results from other proxies.

25

Session on PAGES Focus 1

Focus 1: Climate ForcingsThis Focus fosters activities that aim to produce improved, extended, andconsistent time series of climate forcing parameters, both natural andanthropogenic, including solar insolation and irradiance intensity, volcanic activity,
land cover, sea ice, and greenhouse gas and aerosol concentrations. Furthermore,
Focus 1 aims to quantitatively understand the causes and impacts of variations inclimate forcings, including climate sensitivity and the carbon cycle-climate
feedback.

Overarching Questions- How did the main climate forcing factors vary in the past?
- How sensitive was (and is) the climate system to these forcings?
- What caused the natural greenhouse gas and aerosol variations?
- To what extent can paleodata constrain the climate sensitivity and the carbon
cycle-climate feedback?
- In what precise sequence and over what timescales did changes in forcings,
climate, and ecological systems occur?

Theme Goals- Orbital solar insolation - To tie together the timing of insolation changes and ofclimatic and environmental responses and to unravel how the geometric, spatial,
and seasonal components of orbital insolation changes affected the Earth
System.
- Solar irradiance – To improve the documentation and understanding of solar
irradiance variations. This necessitates progress in our understanding of
irradiance proxies, such as sunspot numbers and cosmogenic signatures in ice
cores and tree rings, and that we disentangle solar from non-solar influences.
The ultimate goals are to extend the low-frequency solar forcing record backthrough the entire Holocene, retrieve more detailed and spatially distributed
records of cosmogenic isotopes, and interpret them in association with modelingof the mechanisms affecting the isotope concentration in ice and marine
sediments.
- Volcanic aerosols – To establish dates, latitude, magnitude and radiative impact

26

Session on PAGES Focus 1of explosive volcanic eruptions through correlation of more ice core records andthe development of new tracers, such as the identification of stratosphericeruptions through studies of isotopes in sulfate. The ultimate goal is to extend
the detailed record of volcanic forcing through the entire Holocene.

27

Session on PAGES Focus 1

Detecting Holocene sea level changes of Antarctic ice sheet
Yusuke Yokoyama*
Masako Yamane, Naohiko Ohkouchi and Hiroyuki Matsuzaki* University of Tokyo
Mid to Late Holocene sea-level change can be used for evaluating long-term
stability of the Antarctic ice sheet since the end of the last major, approximately 8,000
years ago. Ongoing global warming may trigger disintegration of this ice sheet, withcollapse of the West Antarctic Ice Sheet alone potentially producing a more than 3 to 4
m global sea-level rise. Relative sea level records from sites far away from former ice
sheet regions (far-field) provide information on total volume of the ocean mass change,
which can be interpreted as global ice volume change. However, understanding
mechanisms for the ongoing ice sheet fluctuations requires information on the source of
meltwaters, provided by records near the Antarctic ice sheet. To address the paucity of
information from this region, we have employed two new methods to understandmelting history of Antarctic ice sheets, namely cosmogenic radionuclides (CRN) andcompound specific isotopes (CSI) measurements, both of which will provide a more
complete history of ice sheet behavior. Cosmic rays began bombarding the surface ofrocks in Antarctica after deglaciation. Hence, the amount of CRN is proportional tominimum exposure age after ice sheet ablation. CSI is useful for analysis of sediments
proximal to ice sheets due to the differing isotopic signals between ice and seawater, up
to ca. 300 per mil for hydrogen isotopes. Therefore, meltwater signals can be recorded
in CSI produced from surface dwelling algae. Another major obstacle for Antarctic
marine geological study is the difficulty in applying radiocarbon dating for to two basic
reasons; lack of foraminifers and anomalously old TOC ages because of old carbon
contamination from the Antarctic continent. We are using compound specificradiocarbon dating to solve this problem. In this presentation, we introduce these two
measures to reconstruct the melting history of Antarctic ice sheet during the Holocene
using two particular examples from Lutzow Holm bay in East Antarctica and Ross Seaof West Antarctica.

28

Session on PAGES Focus 1

Historical changes in solar activity and its impact on regional-global
climateHiroko Miyahara1, Yusuke Yokoyama2, Yasuhiko T. Yamaguchi2, Kazuho
Horiuchi3, Takeshi Nakatsuka4, Hiroyuki Matsuzaki5, Stewart Fallon6
1 Institute for Cosmic Ray Research, The University of Tokyo, 2 Atmosphere and Ocean
Research Institute, The University of Tokyo, 3 Graduate School of Science andTechnology, Hirosaki Univerisy, 4 Department of Earth and Environmental Sciences,
Nagoya University, 5 Department of Nuclear Engineering and Management, The
University of Tokyo, 6 Australian National University
In this paper, we present the history of 11-year/22-year solar and cosmic-ray cycles in
the past reconstructed from the measurements of carbon-14 content in annually resolved
tree rings. Based on the reconstruction, we discuss the variability of solar activity in thepast as well as the influence of the variable solar and cosmic-ray decadal cycles on
climate change.
The long-term variations of solar activity are often reconstructed based on decadal
data of cosmogenic nuclides, however, it is difficult to eliminate the effect of thechanges in climate change, geomagnetic field intensity, and the anthropogenic effect. So
far, multiple scenarios for the long-term variation of solar activity level have beensuggested based on the records of cosmogenic nuclides; such as the carbon-14 content
in tree rings and the beryllium-10 content in ice cores from polar regions. It prevents us
to determine the unique scenario for the history of solar irradiance as an input parameterof climate modeling. We therefore examined the changes of absolute solar activity levelby detecting the shortening/ lengthening of the 11-year solar cycles.
We have also examined the influence of the shortening/lengthening 11-year/22-year
solar and cosmic-ray cycles on climate change during the Little Ice Age and theMedieval Warm Period. The solar cycles are lengthened to be ~14 years/~28 years at
low solar activity level, and are shortened to be ~9 years/~18 years at high solar activity
level. We have found that climate cycles are also modulated according to the changing
solar cycles. We also find that the 22-year cycles are playing important role in climatechange at decadal to multi-decadal time scales (Figure). The 22-year cycle is associatedwith the reversals of solar magnetic field polarity, and thus is only prominently
recognized in the variation of incident cosmic rays at the earth. The mechanisms how
the climate system responds to the changes in cosmic rays need further investigations.

29Session on PAGES Focus 1

Maunder Minimum mode

＋

‐

＋

‐

＋

‐

＋ ‐ ＋

Temperature
index

Solar polarity ‐Sunspot number

14C anomaly (inversed)

Year AD
Sunspot number: Hoyt and Schatten, 1998
Temperature index: Vinther et al., 2003
Solar cycle and magnetic polarity, Miyahara et al., 2008, 200930

Session on PAGES CCT 3

Cross-Cutting Theme 3: Modeling
Numerical models provide a comprehensive, quantitative, and physically coherent
frameworkfor

exploringcouplings and feedbacks between the various

components of the Earth System, and as such, modeling is a key element of all the
PAGES Foci. Some paleo-specific modeling issues are generally not as relevant tothe communities developing Earth System models for future projections.
Accordingly, this theme supports efforts to improve model components specificfor paleoresearch requirements.

Goals
1. Fostering the development of strategies for proxy modeling.
To maximize the anticipated synergy, focus will be on proxies with wide spatial
coverage and for which large data collections already exist (e.g., stable
isotopes reflecting the physical and biogeochemical processes in the Earth
System). Strategies for including proxies such as aerosols or pollen will also be
developed.
2. Devising methods for the objective comparison of proxy data and modeling
results.
In present-day climatology, data assimilation has become an important toolfor quantifying the state of the climate system based on observations.
However, these methods are not readily available for the sparsely distributed
paleodata. Successful strategies for assimilation of paleodata could also help
scientists working on proxy-based reconstructions to optimize the selection ofsampling locations and will be promoted by this CCT. Another issue arises fromthe fact that proxy-based reconstructions are often widely spaced andassociated with uncertainties that are not well constrained. The lack of suitablestatistical methods for comparing such data with model output will be
addressed by the CCT. This includes strategies for downscaling the output ofglobal models to regional scales (e.g., for lake level, ice sheet, fire, coastal
upwelling, or aerosol transport models) are still immature and will bepromoted by the CCT. In addition, the CCT will stimulate the development of31

Session on PAGES CCT 3

coupling techniques for two-way nesting of coupled regional and global climate
models.
3. Promoting the development of comprehensive ESM families.
The long timescales associated with geological processes often require
integration times that are significantly longer than those used for generating
future climate scenarios. To meet this requirement and also rely on the same
type of models used in the IPCC community, models should be offered with arange of resolutions and system components suitable for long paleoclimate
experiments.

32

Session on PAGES CCT 3

Forcing and feedbacks for the change of climate and sea level
throughout the glacial-interglacial cycle: A modelling perspective inJapan
Ayako Abe-Ouchi1,2
1. University of Tokyo, 2. JAMSTEC
Aiming at the better understanding on the mechanism of climate change and the furthur
validation of climate models used for future projection, paleoclimate modeling using
GCM is conducted by 2 groups in Japan. One is lead by Dr. A. Kitoh at MRI/JMA using
MRI-GCM, amd the other is lead by myself at University of Tokyo and at JAMSTEC
using MIROC-GCM. Both groups have been participated in the PMIP (Paleoclimate
Modelling Intercomparison Project) which was kicked off in 1995; in the first phaseusing only the atmospheric model, in the second phase coupling to the dynamical ocean(Bracconot et al, 2007, Otto-Bliesner et al, 2007, 2009 and others) and now preparing
for the 3rd phase introducing new components in the climate model such as dynamical
vegetation, carbon cycle etc..with updated boundary conditions and new experimentsfrom Pliocene (3.5Ma) to the last millenium. Here I introduce our recent activity on
paleoclimate modeling mainly using MIROC and discuss the direction towards IPCC
AR5 and the necessity of possible collaboration with the paleo-data community.
References
Abe-Ouchi, A.,et al 2007, Clim. Past, 3 , 423-438.
Braconnot, P., et al 2007: Clim. Past, 3, 261-277.
Braconnot, P., et al , 2007: Clim. Past, 3, 279-296.
Hargreaves JC, et al 2007, Clim. Past 3 (1): 77-87
Kurahashi-Nakamura, T. et al, 2007, G. R. L., 34, L20708,
Kurahashi-Nakamura, T.,et al , in press.
Murakami, S., et al 2008, J. Climate, doi:10.1175/2008JCL12104.1.
Ohgaito, R. and A. Abe-Ouchi, 2009, Climate Dynamics, in press,
Ohgaito, R. and A. Abe-Ouchi, 2007, Climate Dynamics,
DOI10.1007/s00382-006-0217-6
O’hishi, R., et al G.R.L. in press
O’hishi, R. and A. Abe-Ouchi, Climate Dynamics, in press
Otto-Bliesener, BL,et al 2007, G. R. L., 34, L12706
Otto-Bliesner, B.L., et al 2009, Climate Dynamics, DOI:10.1007/s00382-008-0509-0.

33

Session on PAGES CCT 3

Saito, F. and A. Abe-Ouchi, Annals of Glaciology, 55, in press.
Takemura,et al, 2009, Atmos. Chem. Phys, 9, 3061-3073.
Timm, O.,et al, 2008, Paleoceanography, 23, PA2221.
Yanase W., and A. Abe-Ouchi, 2007, Clim. Past, 3, 439-451.
Yanase, W. and A. Abe-Ouchi, Journal of Climate, in press.
Yoshimori, M., et al, 2009, J. Climate, 22(12), 3374-3395

34

Session on PAGES Focus 3 & CCT 1

Focus 3: Global-scale Earth System Dynamics
This focus looks at large-scale interactions between components of the Earth
System (atmosphere, biosphere, cryosphere, hydrosphere) and the links between
regional- and global-scale changes. It hosts activities to synthesize records at a
global scale, acting as an umbrella for the regional studies of Focus 2 and as a linkto the forcings addressed in Focus 1. Working groups address global-scale abrupt
and gradual Earth System changes and their underlying processes, including their
response to changes in forcings, internal feedbacks and teleconnections.

Overarching Questions- How do large-scale changes in the Earth System affect regional climaticand environmental conditions?
- How have regions or Earth System components interacted to produce
climate and environmental variations on a global scale?
- What are the causes and thresholds of rapid transitions between
quasi-stable climatic and environmental states, in particular on timescales
that are relevant to society? How reversible are these changes?

Focus Goals
Variability of the Hydrological Cycle:- To unravel the mechanisms causing variations in both the global andregional monsoon systems.
- To identify and understand teleconnections between global- andregional-scale monsoon variations and other components of the climate
system.
- To disentangle the processes leading to shifts in the position and strengthof the ITCZ at interdecadal-to-millennial timescales.
Rapid Climate Change:-

Combinewell-dated

records

ofcentennial

tomillennial-scaleoceanographic and climatic change during the Holocene, the last glacial
period,andpreviousinterglacials

using

both

bipolarcomparisons of data with rigorous quality and age control.

35

and

globalSession on PAGES Focus 3 & CCT 1- Characterize the rate of abrupt changes and their temporal relation to theunderlying forcings and feedback processes.
- Use data compilations to assess hypotheses on the drivers and effects ofpast MOC changes to inform assessments of the possibility of such changes
in the future and of their potential impacts.
Climate Variability within and between Interglacials:- Combine well-dated records of multiple glacial cycles over at least the icecore era (800 ka), with the particular goal of understanding the spatial
pattern and temporal trends within interglacials.
- Constrain the extent of changes in sea level and ice-sheet extent in pastinterglacials (link to Focus 1 and PALSEA).
- Determine the variability at multi-annual to millennial timescales within
warmer interglacials of the last 800 ka.
Paleo-perspectives on Ocean Biogeochemistry:- Compile proxy evidence for past global changes in the oceanic N and Fe
cycles during rapid climate transitions and to unravel the mechanisms
causing the variations.
- Quantify the response of marine organisms and ecosystems to acidificationand their feedback on atmospheric CO2 using paleoceanographic records ofhistoric acidification, as well as examples from high CO2 worlds in Earthhistory.
- Compile proxy data on marine productivity at glacial-interglacial andshorter timescales to assess the overall efficiency of the marine biologicalpump under different climatic boundary conditions.

36Session on PAGES Focus 3 & CCT 1

Millennial-scale climatic changes during the last seven glacial periods:
perspective from the Dome Fuji ice core records
Kenji Kawamura*
The Dome Fuji Ice Core Project Members* National Institute of Polar Research
Millennial-scale climate variability with inter-hemispheric seesaw during the last glacial
period has been documented in a wide variety of paleoclimatic proxies. However, its
frequency and magnitude for the older glacial periods, as well as prerequisite of themillennial-scale variations, are still uncertain. We present a new 3,035-m (720,000-yr)
ice core record from Dome Fuji, Antarctica. Combination of the two records permits
clear identification of multi-millennial-scale warming events in Antarctica (large
Antarctic Isotope Maxima, LAIM). LIAM are found to have persisted over the last
seven glacial periods, with an overall relationship between the duration of glacial period
and the number of events. The Dome Fuji core has thick annual layers (2-3 times thicker
than those in the Dome C core) for Marine Isotope Stage 16, the oldest glacial period in
the core. Dust flux in this MIS shows millennial-scale variations that are negatively
correlated with temperature, suggesting a link of Antarctic temperature with aridity inPatagonia, as seen in the last glacial period. In order to gain further insight into theprerequisite of occurrence of bipolar seesaw, we conducted 1000-yr climate simulations
with freshwater forcing (0.05 Sv into the northern North Atlantic) using a fully coupledatmosphere-ocean general circulation model (MIROC GCM). The results suggest thatlarge Antarctic warming and Austral precipitation increase in response to northern
freshwater forcing only occur when the combination of background coldness and fresh
water amount exceeds some threshold. However, occurrences of very large AIMs inearly parts of glacial periods (e.g. MIS 5a-5d) apparently contradict with a thresholdconcept (such as a need for Antarctic temperature 4 ˚C below Holocene level to produce
climate instability, see Loulergue et al., 2007). We speculate that Antarctica ultimately
became warmer than the threshold due to intense precession forcing (northern summer
insolation), which would maintain the freshwater supply into the North Atlantic bymelting ice sheets. This could explain the absence of massive iceberg discharges(Heinrich events) for the large but infrequent bipolar seesaw sequences in the early partsof glacial periods, when ice volume was relatively small (thus relatively stable) but
precession amplitude was large.

37

Session on PAGES Focus 3 & CCT 1

Millennial-scale Asian monsoon dynamics, its
mechanism, and possible linkage with solar activity

tele-connection

Ryuji Tada
Department of Earth and Planetary Science, the University of Tokyo
It has been known for some time that East Asian summer monsoon [EASM]
varied significantly in association with millennial-scale climatic changes observed in
North Atlantic and Greenland (known as Dansgaard-Oeschger Cycles) during the lastglacial period. It is also suggested that EASM varied in association withmillennial-scale climatic changes in North Atlantic during Holocene, although theassociation is not necessarily well-established. The tele-connection is probably throughchanging meandering pattern of subtropical westerly jet because the position of westerly
jet over East Asia during summer bounds the northern limit of EASM. During glacial
stadials, the westerly jet axis migrated southward and prevented inland penetration of
EASM front, whereas the westerly jet axis migrated northward and allowed inland
penetration of EASM front during glacial interstadials. On the other hand, the relation
between the position of the westerly jet over East Asia and cold-warm climate in the
North Atlantic seems to be opposite during Holocene, and presence or absence ofLaurentide Ice Sheet could have been responsible for the changes in meandering patternof the westerly jet between glacial period and Holocene.
Millennial-scale changes in monsoonal climate are also observed in low (tomiddle) latitude northern hemisphere, which seems to be closely associated with the
behavior of ITCZ as well as the westerly jet. The spatial pattern of millennial-scale
climatic changes (such as temperature and precipitation) reconstructed in the low (tomiddle) latitude northern hemisphere during Holocene is similar to the pattern of thedifference in climatic conditions (such as temperature and precipitation) between thesolar activity maxima and minima, suggesting possible connection with the solar
activity. It is possible that low latitude changes in climate pattern in association withchanges in solar activities could be the trigger of the millennial-scale climatic changes
which propagate into the high-latitude northern hemisphere through changes inmeandering pattern of ITCZ and the westerly jet.

38Session on PAGES Focus 3 & CCT 1

Cross-Cutting Theme 1: Chronology
Chronology is crucial to paleoresearch and often constrains the strength ofconclusions from paleoenvironmental reconstructions. This Theme supports
efforts to improve tools for absolute and relative dating, and to enhance thereliability of reference timescales. It also encourages creative new approaches tosolving chronology issues.

Goals
Improve absolute dating:•

reduce the uncertainty of existing radiometric dating methods, i.e., 14C,
40

K/40Ar, 40Ar/39Ar, Uranium-series;•

improve calibration techniques, particularly for 14C calibration curves andluminescence ages using tree rings, sediment varves, etc.;•

develop new dating methods, e.g. for the time beyond the range of U/Th
dating (before ~300,000 years);•

promote laboratory dating intercomparisons (e.g., Ar constants).

Improve chronostratigraphic dating:•synthesize correlations of regionally occurring well-dated tephra on land andin the ocean with the ice core record;•

compile paleomagnetic master curves for all parts of the globe, including theircentennial and millennial-scale variations.

Improve event stratigraphy:•

establish regional event stratigraphy master curves such as the GICC05
coordinated effort by the INTIMATE group of the North Atlantic (Lowe et al.,2008) based on NGRIP ice core;•develop a global network of high-resolution climate records from different
regions and archives, with their time scales consistent between the records
and relative to orbital solar insolation over at least the Mid-and Late
Pleistocene;

39Session on PAGES Focus 3 & CCT 1•

establish a high-resolution master curve of past global mean sea level change
and spatial synopses of local changes.

40Session on PAGES Focus 3 & CCT 1

Ocean circulation in the North Pacific during the last glacial
termination
Yusuke Okazaki1, Axel Timmermann2, Laurie Menviel2, Naomi Harada1, Megumi
Chikamoto1, Ayako Abe-Ouchi1, 3, and Hirofumi Asahi3
1. Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Japan
2. International Pacific Research Center (IPRC), University of Hawaii, USA
3. Atmosphere and Ocean Research Institute, University of Tokyo, Japan
During the termination of the last ice age between 15 and 17.5 ka, the Atlantic
Meridional Overturning Circulation (AMOC) substantially weakened due to freshwater
forcing by melting icebergs in the North Atlantic (Heinrich Event 1; H1). The effects ofthis major reorganization of ocean circulation were documented globally. Althoughpaleoproxy studies argued Pacific intermediate and deep water ventilation changes
during the last termination, there is no comprehensive agreement. In order to provide amore comprehensive view on what triggered ventilation changes in the North Pacificduring the last termination, we compiled a dataset of published radiocarbon sedimentcore data in the North Pacific. Together with a climate model simulation, that mimics
H1, we determine the effects of AMOC changes on the large-scale conveyor-belt
circulation, with an emphasis on the North Pacific. Both sedimentary record andmodeling simulation strongly suggest that deep water was formed in the North Pacificextending to a depth of ~2500-3000 m during H1, establishment for a deep Pacific
Meridional Overturning Circulation (PMOC). Once the PMOC establishes, thepoleward surface currents transport more saline subtropical waters into the North
Pacific, thereby providing a positive salinity feedback. A closed Bering Strait facilitates
the build-up of such North Pacific salinity anomalies. The main simulated pathway of
deepwater spreading is along the western margin of the North Pacific, in a deep westernboundary current analogous to the one currently in the North Atlantic. The model results
demonstrate that the western boundary flow is the principal factor in establishing theeast-west gradient of intermediate-deep-Pacific ventilation, which is also evident in thecompilation of radiocarbon-based ventilation data.

41

Session on PAGES Focus 3 & CCT 1

Large-scale blooms of Emiliania huxleyi in the Bering Sea during thepast 100 years and its implication of recent global biogeochemicalchangesNaomi Harada*1, Miyako Sato1, Kazumasa Oguri1, Osamu Tadai2, Sei-ichi Saito3,
Kyoko Hagino-Tomioka4, Yoshihiro Shiraiwa5, Yoshinori Tsuji5, Susumu Konno6,
Richard W. Jordan6, Kota Katsuki7, Kyung-Hoon Shin8, Hisashi Narita9
1
Japan Agency for Marine-Earth Science and Technology; 2Marine Works Japan Ltd.;
3
Hokkaido University; 4Okayama University; 5University of Tsukuba; 6Yamagata
University; 7Kochi University; 8Hanyang University; 9Tokai University
Temporally and spatially large-scale blooms of Emiliania huxleyi (E. huxleyi)
have been distinguished annually in the eastern continental shelf of the Bering Sea since1997, because ocean color imagery with data from the satellite-borne Sea-viewing Wide
Field-of-view sensor was launched in this year. In 1997, a combination of atmosphericmechanisms produced summer weather anomalies such as calm winds, clear skies, andwarm air temperature over the Bering Sea and the weather anomalies caused depletionof the subpycnocline nutrient reservoir (Napp and Hunt, 2001). After depletion of
nitrate and silicate, a sustained bloom of E. huxleyi was observed (Stockwell et al.,2001). Because of the speed and magnitude with which parts of the Bering Sea
ecosystem responded to changes in atmospheric factors (Napp and Hunt, 2001) andbecause a bloom of the coccolithophorid, Coccolithus pelagicus has also been detectedin the northeastern Atlantic Ocean off Iceland every year since 1997 (Ostermann, 2001),
the appearance of an E. huxleyi bloom in the Bering Sea could be related toatmospherically forced decadal oscillations or global factors.
We have investigated temporal development of E. huxleyi bloom on thecontinental shelf in the Bering Sea by a biomarker of E. huxleyi, C37 alkenones flux
recorded in the sediments during the past 100 years. As a result, the E. huxleyi bloom
had already been prominent since the middle of 1970’s. We also found the relationshipbetween E. huxleyi bloom and activity of Aleutian low and anomaly of Pacific decadaloscillation, however only PDO could not explain the recent high frequent occurrence of
E. huxleyi bloom. A slightly drop of sea surface salinity might promote E. huxleyi
growth in the Bering Sea, too. In this presentation, we will also suggest the implicationsof this regional E. huxleyi bloom to understand recent changes in global biogeochemical
cycles.

42

Session on PAGES Focus 3 & CCT 1

References
Napp and Hunt, 2001, Fish Oceanogr., 10, 61-68.
Ostermann, 2001, WHOI annual report, pp.17-18.
Stockwell et al., 2001, Fish Oceanogr., 10, 99-116

43