Arctic sea ice extent, after reaching its seasonal minimum last week, has begun its annual cyclical increase in response to the setting sun. A cooler melt season, retention of first-year ice, and dispersive ice motion set the 2008 melt season apart from 2007.
Overview of conditions
Arctic sea ice extent on September 23, 2008, was 4.59 million square kilometers (1.77 million square miles), an increase of 77,000 square kilometers (30,000 square miles) above the minimum extent of 4.52 million square kilometers (1.74 million square miles) measured last week.
Conditions in context
Arctic sea ice extent, after reaching its seasonal minimum last week, has begun its annual cyclical increase in response to autumn cooling. The ice will grow over the cold, dark winter months and reach its maximum annual extent sometime next March.
High retention of first-year ice
Perhaps the most interesting aspect of the 2008 melt season was the higher-than-average retention of first-year sea ice (see earlier entries, including April 7). Relatively thin first-year ice is more prone to melting out completely than older, thicker ice. However, more of this year’s first-year ice survived the melt season than is typical. Sea ice age maps from Sheldon Drobot, our colleague at the University of Colorado at Boulder, show that much more first-year ice survived in 2008 than in 2007. This is one of the reasons that 2008 did not break last year’s record-low minimum.
Funny, as Julie points out, where is this news in the media? I guess if the facts don’t fit your theory, you ignore them.
Update: It has now been reported, thanks to Mark Steyn reference to the Investor’s Business Daily article that exposes the current cooling trends.
It may already be happening. The four major agencies tracking Earth’s temperature, including NASA’s Goddard Institute, report that the Earth cooled 0.7 degree Celsius in 2007, the fastest decline in the age of instrumentation, putting us back to where the Earth was in 1930.