Sunday, November 28, 2010

Three Notes on Slow Fall Arctic Ice Growth

With November drawing to a close, this month could match the record low Arctic ice extent for November. The slow fall growth of the ice cover is happening this year despite relatively normal weather conditions across the Arctic.

It is the relatively warm temperatures of the ocean waters that are making it hard for ice to form. I wrote previously about the warm surface water temperatures recorded this year in the southern Arctic Ocean, especially in coastal areas. Scientists have also made an effort this year to record sea bottom temperatures, especially in the shallow coastal waters near glaciers. The bottom waters have, in some places, been just as warm as the surface waters. This is the most definite indication so far that the whole ocean is warming up. The ocean is warming in part because, with less ice cover, it takes on more sunlight.

The ocean may be taking on heat from the surrounding land, which is also warming. The most definite indication of global warming is the shrinking permafrost, especially in Siberia. Scientists may argue about the accuracy of thermometers and statistics, but it doesn’t take any instruments to see permafrost melt. Scientists in Siberia say the melting is accelerating and much of Siberia may look like another planet within about 25 years because of the geological effects created by the melting ice in the ground. When the ice melts, it creates narrow valleys a few meters wide. As this happens, roads there are becoming impassable and will need to be rebuilt. The melting ice takes away heat from the surrounding air, cooling it, so after most of the permafrost melts, Arctic temperatures are likely to increase faster.