Scientists from the National Snow and Ice Data Center (NSIDC) warn that most of the Arctic sea ice is currently thin, young ice (only around since last autumn) and that this type of ice is much more vunerable to rapid melting than older, thick ice.

Age of sea ice in the Arctic (March 2007 and March 2008). Image courtesy of the NSIDC.

What about Arctic sea ice area that was supposedly greater than last year at this time? Indeed, the Arctic sea ice area during March of 2008 was greater than it was in March of 2007, but the overall trend since 1978 is still on the decline.

Arctic sea ice extent each March since 1978. Image courtesy of the NSIDC

Image courtesy of the NSIDC.

The key to this report is not the area, but the thickness of the ice. Mark Serreze of the NSIDC says that this first-year thin ice is even at the North Pole, which raises the possibility that the North Pole could become ice free by the end of this summer. What worries Serreze more is the fact that multi-year ice (which doesn't melt in the summer) is not accumulating as fast as Arctic ice generally is melting, according to the NewScientist. article

Blue bar indicates amount of first-year (young) ice at the beginning of the melt season, while the red bar indicates how much first-year ice was left at the end of the melt season. Image courtesy of the NSIDC

One factor, which has been previously discussed on this blog, was the positive phase of the Arctic Oscillation during a good chunk of the 2007/2008 winter that caused winds to push multi-year ice out of the Arctic and along the east coast of Greenland.

Arctic Oscillation Index since 1950. Image courtesy of NOAA.

Here is the link to this latest report from the NSIDC.