Looks like the Arctic may have set a record this year after all. The National Snow and Ice Data Center (NSIDC) said today that Arctic sea ice volume likely hit a record low in 2008. They reconfirmed that the sea ice extent (or area) “dropped to the second-lowest level since satellite measurements began in 1979″ and that “Despite cooler temperatures and ice-favoring conditions, long-term decline continues.”
But the big news was the announcement about ice volume, since that has huge implications for future ice loss:
NSIDC Research Scientist Walt Meier said, “Warm ocean waters helped contribute to ice losses this year, pushing the already thin ice pack over the edge. In fact, preliminary data indicates that 2008 probably represents the lowest volume of Arctic sea ice on record, partly because less multiyear ice is surviving now, and the remaining ice is so thin.” [See Figure -- Click to enlarge.]
This figure compares ice age in September 2007 (left) and September 2008 (right). It shows the sharp increase in thin first-year ice (red) and the decline in thick multi-year ice — both “second-year ice” (orange) and “third-year and older ice” (yellow). “White indicates areas of ice below ~50 percent, for which ice age cannot be determined.”
NSIDC explains what prevented 2008 from beating the 2007 record low in ice extent:
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 cooler than 2007, although still warmer than average; 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. “
[Financial Update: It does appear that I lost the first year of my 10-year-bet to Sean (described here), which is no big surprise. NSIDC says "Average sea ice extent over the month of September, a standard measure in the scientific study of Arctic sea ice, was 4.67 million square kilometers," whereas the over/under I agreed to was 4.48. That said, I think the NSIDC release cited here suggests I am very likely to win at least 7 of the remaing 9 bets, which is pretty much what I expected from the beginning. I've actually offered to Sean to give him 2009 and 2010 if he'll settle now. How is that for a deal?]
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