An arstechnica.com article, today, explains that while Arctic ice is melting much faster than scientists predicted, Antarctic sea ice is actually expanding.
Yesterday, the National Snow and Ice Data Center announced that the Arctic melt season was probably over and the Arctic Sea area with at least 15% sea ice will reach a record low point of about 3.41 million square kilometers. That is about half of the typical low point observed in the 1980-2000 era and about 750,000 square kilometers less than the previous low set in 2007. Actually, though, every year since 2007 has seen unusually strong summer melts. The six lowest seasonal minimum ice extents have all occurred in the last six years.
In the Antarctic, however, sea ice is expanding. Warming waters in the Southern Ocean are producing increased snow. This contributes to keeping existing ice cold and adds to the glaciers that feed floating ice sheets. It also creates a layer of fresh water that stays on the surface, insulating the ice from warmer ocean waters below. The result is an ice sheet that is growing despite the warming climate (at least until the point that warming causes more of the moisture to start falling as rain).
The article points out that the Earth's two poles have radically different behavior, at least in part due to the fact that one is an ocean that is largely surrounded by land, while the other is a continent surrounded by ocean.
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