November 6, 2011

Arctic Climate changing fast

Effects from humankind appearing quicker than we expected

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Sound a bit like a street-corner scene from an old movie with a youngster selling newspapers with a large, important headline? Today, the topic that should be in our headlines, but isn't, is climate change. Some new data gives us a view of some startling changes that are occurring in the Arctic right now.

When we talk about the Arctic, let's remember it is an ocean that is surrounded by land. (This is in contrast to the Antarctic, which is land surrounded by ocean.) The North Polar map, with the Pole designated by the black dot in the center, shows minimum sea-ice extent in early September 2011. The larger ring marked "median extent" is the amount of ice for the 1979 to 2000 base period for this date.

This map and data can be accessed at the National Snow and Ice Data Center website.

The white area shown here is very close to, but slightly larger than, the lowest ice extent in the satellite record observed in 2007. The near-record ice melt followed higher-than-average summer temperatures, but "the atmospheric and oceanic conditions were not as conducive to ice loss this year," according to Walt Meier, an NSIDC scientist.

September is normally the time when Arctic sea ice reaches its minimum. When the long, warm polar days shorten and temperatures begin to drop, ice extent begins to increase again. It reaches its maximum around April 1 when the melt cycle begins again.

So let us review some numbers and graph "Arctic Sea Ice Extent." The solid line shows the average ice extent for 1979 to 2000. The dotted line is for 2007, the record low year, while the lower line near the dotted line is for 2011. For 2011, the minimum ice extent was 2.43 million square kilometers (938,000 square miles) less than the 1979 to 2000 average.

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