Hot Winds

One of the rallying cries of the anthropogenic global warming (AGW) crowd is “The Arctic Ice is melting!” The high priests of the AGW faith jumped quickly on this readily observable fact (the Arctic ice sheet has been melting) as evidence of AGW, and their lapdog media followers have repeated this claim endlessly. Something not usually linked with that claim, though, is a different puzzling fact: the Antarctic ice sheet has been growing, and quite dramatically. If AGW is the cause of the Arctic ice sheet shrinking, then why isn't the Antarctic ice sheet also shrinking? Somehow the AGW faithful managed to ignore this inconvenient little observation.

But now NASA has released a new study about the causes of the Arctic ice sheet melting. From the belly of the AGW beast (NASA is the home of the high priest of AGW, Jim Hansen) comes the news that the culprit appears to be a new pattern of winds:

The scientists observed less perennial ice cover in March 2007 than ever before, with the thick ice confined to the Arctic Ocean north of Canada. Consequently, the Arctic Ocean was dominated by thinner seasonal ice that melts faster. This ice is more easily compressed and responds more quickly to being pushed out of the Arctic by winds. Those thinner seasonal ice conditions facilitated the ice loss, leading to this year's record low amount of total Arctic sea ice.

Nghiem said the rapid decline in winter perennial ice the past two years was caused by unusual winds. "Unusual atmospheric conditions set up wind patterns that compressed the sea ice, loaded it into the Transpolar Drift Stream and then sped its flow out of the Arctic," he said. When that sea ice reached lower latitudes, it rapidly melted in the warmer waters.

"The winds causing this trend in ice reduction were set up by an unusual pattern of atmospheric pressure that began at the beginning of this century," Nghiem said.

The Arctic Ocean's shift from perennial to seasonal ice is preconditioning the sea ice cover there for more efficient melting and further ice reductions each summer. The shift to seasonal ice decreases the reflectivity of Earth's surface and allows more solar energy to be absorbed in the ice-ocean system.

The biggest surprise for me in this news is that the NASA press flacks allowed a press release about weather to go out without an obligatory mention of the linkage between this climatic phenomenon and AGW. Ordinarily I'd have expected some completely unsubstantiated mention of how AGW caused this change in wind pattern. The fact that such a statement is missing suggests (a) the scientists involved don't believe such a linkage exists, or (b) the PR flack involved was drunk, stoned, about to quit NASA, or possibly all three.