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A Century of Change in Arctic Sea Ice
Reference
Polyakov, I.V., Alekseev, G.V., Bekryaev, R.V., Bhatt, U.S., Colony, R., Johnson, M.A., Karklin, V.P., Walsh, D. and Yulin, A.V.  2003.  Long-term ice variability in Arctic marginal seas.  Journal of Climate 16: 2078-2085.

What was done
The authors analyzed records of maximum ice extent (1900-2000) and fast ice thickness (1936-2000) in the Kara, Laptev, East Siberian and Chukchi Seas.  The ice extent measurements were first made from a fleet of ships, then aircraft, and finally satellites, while the ice thickness measurements were made at five Russian polar stations by drilling holes through the ice and directly measuring its thickness.

What was learned
With respect to ice extent, in the words of the authors, "over the entire Siberian marginal-ice zone the century-long trend is only -0.5% per decade," while "in the Kara, Laptev, East Siberian, and Chukchi Seas the ice extent trends are not large either: -1.1%, -0.4%, +0.3% and -1.0% per decade, respectively."  Moreover, they add, "these trends, except for the Chukchi Sea, are not statistically significant."

With respect to fast ice thickness, the group of nine U.S. and Russian scientists reports that the available records "do not show a significant trend," noting that "in the Kara and Chukchi Seas trends are positive, and in the Laptev and East Siberian Seas trends are negative," but that "these trends are not statistically significant at the 95% confidence level."

What it means
Polyakov et al. conclude that for the studied sub-regions of the Arctic, "long-term ice thickness and extent trends are small and generally not statistically significant," which is extremely interesting in light of the fact that most of the earth recovered from the global chill of the Little Ice Age over the course of the 20th century.  These observations thus tend to discredit climate model qualitative predictions of amplified warming in earth's polar regions in response to increases in the air's CO2 content, which in turn tends to discredit the models' quantitative predictions regarding the magnitude of CO2-induced global warming, since the predicted amplification is not evident in the regions surrounding either pole [see also in this regard Temperature (Trends - Regional: Antarctica and Arctic) in our Subject Index, as well as Sea Ice (Antarctica)].


Reviewed 21 April 2004