Reconstructing Sea Ice Conditions in the Arctic and Sub-Arctic Prior to Human Observations - Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications - page 40

based on micropaleontological approaches. They also point
to the fact that the “modern” state defined from recent ob-
servation (1954-2000 A.D.) is probably not perfectly repre-
sentative of the mean state of sea ice at the scale of the last
hundreds of years. It would therefore be relevant to improve
our knowledge of sea ice changes over the last hundreds of
years, especially in areas such as the eastern Greenland mar-
gins where sea ice export from the Arctic Ocean determines
thermohaline properties of the northern North Atlantic.
At the scale of the Holocene, a few sea ice time series
from Arctic seas and the subpolar North Atlantic indicate
significant fluctuations of sea ice extent. However, the trends
from the early Holocene to the late Holocene appear different
from one area to another, notably when comparing the west-
ern Arctic and the east Greenland coast on one side and the
northern North Atlantic and subpolar epicontinental seas on
the other side. This implies complex mechanisms involving
the direct thermal effect of insolation, which was higher dur-
ing the early Holocene, but also the rate of sea ice formation
in the Russian Arctic in relation to freshwater budgets and
wind strength, in addition to drift patterns across the Arctic.
Improving the spatial coverage of past sea ice records during
the last thousands of years would certainly help to develop a
more comprehensive picture of sea ice variability on longer
timescales and to help modelers with the challenge of sim-
ulating sea ice under natural forcing, prior to constraining
its evolution in relation with the ongoing anthropogenically
driven changes.

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Acknowledgments. This study is a contribution to the “Polar Cli-
mate Stability Network” of the Canadian Foundation for Climate
and Atmospheric Sciences (CFCAS). Support from the Natural
Sciences and engineering Research Council of Canada and the
Fonds Québecois de Recherche sur la Nature et les Technologies
(FQRNT) is also acknowledged.

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