Something Odd for the Arctic:
"Normal" Sea Ice Extent as Winter Ends

The extent of Arctic Sea Ice was within the average range throughout March 2010, the first time in many months that the extent of Arctic sea ice was anything but well below normal. In this image of the Arctic, the orange line represents the 1979-2000 median sea ice extent, and the white color represents the actual extent of sea ice on March 29, 2010.

Photo: National Snow and Ice Data Center

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Only two months ago, it looked as if the Arctic sea ice extent was trending so far below normal that it might set a new record. The extent of Arctic sea ice, a barometer on global warming and one of the most easily visualized effects of climate change, was 1 million square miles short of average throughout February.

But, lo and behold, so much new ice froze in March that the overall extent for this winter will end up nearly normal, as compared to the long-term average. That's a headline no one could have written for years, as the extent of Arctic sea ice has dropped, rhythmically with the seasons, but dropped precipitously and consistently for years. The record-setting extent of melting in the past three summers was to a degree not expected for decades, under mainstream scientific predictions of just a few years ago.

As the ice melts, polar bear, Pacific walrus, ribbon seals and other species struggle for survival, and the potential for human use grows -- for oil and gas drilling, and for shipping through once ice-locked channels. The extreme melting in the Arctic has been seen as a harbinger for things to come elsewhere at other latitudes: Does it mean that the worst-case predictions for other aspects of global warming are inevitable? Wildfires, droughts, crop failure, sea-level rise, massive rates of species extinctions ... will each appear more quickly, and have more severe impacts than the public expects?

The normal freeze this winter could be another blow for global warming activists, who have seen headline-grabbing news about everything from so-called climate-gate and so-called glacier-gate to so-called snowmagedden, none of which is the Achilles' heel for climate science that global warming skeptics would like them to be. The last decade has been the warmest on record, with no end to the warming anticipated if we don't curb greenhouse gas pollution.

Still, if the Arctic does indeed have one good year among many bad ones, it could further erode public opinion of climate science at a time when the Senate is on the verge of debating sweeping energy and climate legislation. Given the long-term trend, it should not.

Charts: National Snow and Ice Data Center

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