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Thicker Arctic Ice Summer 2009

Page history last edited by Malcolm 14 years, 5 months ago

Over the 2009 Summer, a Spread of Thicker Arctic Ice

By Andrew C. Revkin

The National Snow and Ice Data Center released its summary of summer sea-ice conditions in the Arctic on Tuesday, noting a substantial expansion of the extent of “second-year ice” â€" floes thick enough to have persisted through two summers of melting. The result could be a reprieve, at least for a while, from the recent stretch of remarkable summer meltdowns.

According to the center, second-year ice this summer made up 32 percent of the total ice cover on the Arctic Ocean, compared with 21 percent in 2007 and 9 percent in 2008. The percentage of ice that was many years old, forming thick pancaked expanses, was at its lowest since satellite observations began 30 years ago. But that could change next year as the second-year ice adds mass through the long winter freeze.

http://nsidc.org/images/arcticseaicenews/20091005_Figure4_thumb.png

Walt Meier, an ice center scientist, described the situation this way in a statement:

We’ve preserved a fair amount of first-year ice and second-year ice after this summer compared to the past couple of years. If this ice remains in the Arctic through the winter, it will thicken, which gives some hope of stabilizing the ice cover over the next few years. However, the ice is still much younger and thinner than it was in the 1980s, leaving it vulnerable to melt during the summer.

The shifting conditions raise a question. None of the sea-ice specialists I’ve interviewed since 2000 on Arctic trends ever predicted a straight-line path to an open-water Arctic, but quite a few have stressed the longstanding idea that as white ice retreats, solar energy that would have been reflected back into space is absorbed by the dark sea, with that heat then melting existing ice and shortening the winter frozen season. I’ve just sent out a query to a batch of experts, asking if the potential ice recovery now raises questions about the importance of that light-dark shift in albedo compared to other dynamics in the Arctic Ocean. I’ll update this post as responses come in.

The conditions also bolster the views of ice and climate specialists who have stressed that the many factors shaping Arctic conditions year by year, from winds and atmospheric pressure to highly variable ocean currents and soot, still dominate the influence of heat trapped by building greenhouse gases. So the “ death spiral of the Arctic ice system” could well be more like a series of descending loop the loops. Whether the Arctic’s 21st-century journey ends with a tipping-point style crash or a whimper remains uncertain, but â€" even with the current recovery â€" it’s hard to find a researcher probing Arctic ice trends who does not foresee open-water summers, and all that comes with them, in coming decades, as long as greenhouse gases keep accumulating in the atmosphere.

 

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