Monday, October 13, 2008

The Ice Comeith

News of the imminent demise of the Arctic ice cap at the peak of the summer melt have turned out to be very much exaggerated. It was widely reported in June that (see this BBC article featuring a photo of a cute seal apparently worried that it would soon have no more ice to play on) the 2008 summer melt would produce a new record minimum ice cover set only a year earlier. By late August the risk of a new record minimum was significantly reduced. However in an this late August BBC article, scientists from the US-based National Snow and Ice Data Center (NSIDC) reportedly said that:
the NSIDC team believes last year's record could still be broken even though air temperatures, both in the Arctic and globally, have been lower than last year.
This negative assessment turned out to be positively incorrect. The 2008 minimum turned out to be about 400,000 square kilometers greater than the 4.3 million square kilometer minimum recorded in September of 2007. There was also more good cheer to be had in the article:

"We could very well be in that quick slide downwards in terms of passing a tipping point," said Mark Serreze, a senior scientist at the Colorado-based NSIDC.

"It's tipping now. We're seeing it happen now," he told the Associated Press news agency.

Pity the ice doesn't understand humans and human logic. As the figure below released by the NSIDC clearly shows, the ice is making a remarkable comeback this fall:

The blue line shows the extent of the Arctic ice over the past four months. The upper, grey line shows the average over the 1979-2000 period over the comparable period as does the dotted green line for 2007. Notice how rapidly the polar ice cap is recovering after this year's summer melt season (as evidenced by the upward steepness of the blue line). Is is possible that the Arctic ice is beginning a cyclical recovery after hitting it's all-time recorded low in 2007?

Such a thought is not possible if you are a scientist at the NSIDC. According to a NSIDC press release made on October 2nd:

In the end, however, summer conditions worked together to save some first-year ice from melting and to cushion the thin pack from the effects of sunlight and warm ocean waters. This summer’s weather did not provide the “perfect storm” for ice loss seen in 2007: temperatures were lower than 2007, although still higher than average (Figure 5); cloudier skies protected the ice from some melt; a different wind pattern spread the ice pack out, leading to higher extent numbers. Simply put, the natural variability of short-term weather patterns provided enough of a brake to prevent a new record-low ice extent from occurring.

NSIDC Research Scientist Julienne Stroeve said, “I find it incredible that we came so close to beating the 2007 record—without the especially warm and clear conditions we saw last summer. I hate to think what 2008 might have looked like if weather patterns had set up in a more extreme way. ”

The melt season of 2008 reinforces the decline of Arctic sea ice documented over the past thirty years (Figure 6 and Figure 7). NSIDC Lead Scientist Ted Scambos said, “The trend of decline in the Arctic continues, despite this year's slightly greater extent of sea ice. The Arctic is more vulnerable than ever.”

Perhaps this is true and perhaps this is just a temporary reprieve from a long term trend. But what if it is not? What if it is the beginning of a cyclical recovery in the Arctic ice cap? While it is entirely possible that this year's modest increase in the Arctic ice's minimum extent was just a random event during a terminal decline in the Arctic ice cap during the summer, it is also possible that this is the beginning of a cyclical recovery in the ice. But then again, what funding would you be able to get if the Arctic ice's summer melt begins to diminish?

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