CAPE 2000

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ICAPP 2000

Second Circular

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Sessions

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The Kirkjubaejarklaustur meeting will address the role of sea ice in the climate system, focussing on the evidence for changes in sea ice extent across the North Atlantic Arctic during the Late Quaternary. The North Atlantic Arctic is defined broadly as those areas that are influenced strongly by ocean currents of the North Atlantic. This region extends from the Eastern Canadian Arctic (Labrador to Ellesmere Is) through to the Kola Peninsula of Russia, and includes the North Atlantic and Arctic oceans and their adjacent marginal seas (e.g. the Labrador, Barents, Norwegian, Greenland and Iceland seas).

Sea ice is an important variable in the planetary energy balance. Because sea ice greatly restricts the exchange of energy between ocean and atmosphere, and its high albedo reflects much of the incoming solar radiation, changes in sea ice extent impact local climate, pole-to-equator pressure gradients, and can influence thermohaline ocean circulation. GCM simulations of a 2xCO2 world indicate that the greatest warming will occur over the Arctic, principally because of the modeled reduction in sea ice. Sea ice models currently incorporated in GCMs have difficulty accurately modeling the modern seasonal cycle of sea ice distribution. Hence, future predictions have large uncertainties.

Presently, Arctic sea ice extends over 14 million square kilometers at its winter maximum, receding to about half this area by autumn. Historic records of sea ice variations around Iceland over the past millennium indicate substantial inter-decadal to century-scale variability, with potential for significant societal impacts. North Atlantic sea ice variability over the past century may be linked to the North Atlantic Oscillation. Most estimates of sea ice extent at the LGM show a dramatic extension into the North Atlantic and North Pacific oceans. Conversely, sea ice was significantly retracted in the early Holocene, and may have been even more restricted at the peak of the last interglacial. However, evidence for these retracted states has yet to be synthesized.

The central focus of the CAPE 2000 meeting will be the development of an improved data-based compilation of multi-proxy evidence for sea ice variations across the North Atlantic Arctic during the Late Quaternary, using internationally recognized data-management procedures. One goal of this effort will be to develop a set of rules to interpret sea ice from various lines of proxy evidence, similar to the rule-based pollen-vegetation relationships that were developed at Lammi, and subsequently in Europe and Canada for the marine realm. These rules provide an objective basis for the conversion of proxy data into specific environmental variables. A second goal will be evaluate to what extent the paleo-data can be used to define large-scale controls on North Atlantic sea ice.


Meeting Topics:

  • Sea ice proxies
    • Open-ocean proxies
    • Nearshore proxies

  • The role of sea ice in the climate system
    • Implications for ocean circulation changes
    • Response of terrestrial ecosystems in the coastal zone
    • Sensitivity of terrestrial temperatures to changes in sea ice
    • Sea ice extent and the North Atlantic Oscillation

  • Sea ice variability in the Late Quaternary
    • Historical records of sea ice variability
    • Minimum sea ice extent in the Holocene
    • Sea ice at the Last Glacial Maximum
    • Minimum sea ice extent during the Late Quaternary

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