"NSIDC: Arctic “melt season in high gear”"
The National Snow and Ice Data Center has a July 6 update on Arctic ice melt:
The Arctic is now in the midst of the summer melt season. Through most of June, ice extent tracked below the 1979 to 2000 average, and slightly above the levels recorded during June 2007. Warm temperatures and southerly winds led to quickly declining ice concentration in some regions, such as the Laptev Sea….
Compared to previous Junes, ice extent in June 2009 was extremely close to the last two years, falling within 30,000 square kilometers (12,000 square miles) of the June extent in 2007 and 2008. The long-term trend indicates a decline of 3.3% per decade, an average of 40,100 square kilometers (15,500 square miles) of ice per year.
Will we see a record minimum this year?
The warmth in the Laptev Sea is consistent with a pattern of southerly winds in these areas, which can be linked to the area of low atmospheric pressure centered just north of Novaya Zemlya Island. Note also the strong high-pressure cell (an anticyclone) over the northern Beaufort Sea.
This contrast between high and low pressure is broadly similar to the atmospheric circulation pattern that set up in 2007. In 2007, that pattern contributed to a significantly accelerated decline in ice extent during July, and a record minimum low in September. Will the same acceleration in ice melt occur this year? If so, a new record low minimum extent becomes more likely. So far, an acceleration has not been observed. As July progresses, the Arctic sun gets lower on the horizon, incoming solar energy decreases, and the chances of such a rapid decline become less likely.
Bottom Line: Too early to say.
I would note that we are only getting a two-dimensional look at sea ice extent. From a three-dimensional perspective, 2008 was probably the record low Arctic ice volume (see NSIDC stunner: Arctic ice at “Likely Record-Low Volume”), and we will likely be close to that this year.
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- NSIDC: Arctic melt passes the point of no return, “We hate to say we told you so, but we did.”