The annual Arctic sea ice melt season is nearing an end, while the Antarctic sea ice season has almost reached its annual maximum.
Arctic sea ice extent much higher than last year, but still below normal
The main reason that the sea ice did not decline as much as some other recent years is that summer temperatures have been mostly below average in the central Arctic Ocean and into Greenland as sea level pressure has remained below normal. This pattern also led to less surface melting on the Greenland Ice Sheet.
The NSIDC image below shows the low-level summer temperature anomalies in the arctic this past summer compared to two base periods (1981-2010, 2007-2012).
Key excerpt from the NSIDC.....
Even though extent at the beginning of this summer was similar to last year, the melt season ended with considerably more ice. This is not surprising, as climate models consistently project that there will be large variations in summer ice extent from year to year. A cool summer can help to retain a thin layer of ice, increasing the overall ice extent. Conversely, a warm summer can help to remove much of the thin ice cover.
The NOAA image below shows the summer 2013 sea level pressure anomalies. Note the well below-normal anomalies from the central Arctic to Greenland.
Arctic sea ice volume
Arctic sea ice volume, which is a better indicator of the health of sea ice, is running close to what it was back in 2010 and 2011, but higher than 2012.
However, the longer term trend is clearly downhill. Image courtesy of the Polar Science Center from the University of Washington.
Antarctic sea ice extent at a record high
Looks like back to back (2012-2013) record sea ice extent in the Antarctic. According to the National Snow and Ice Data Center (NSIDC), current sea ice extent in the Antarctic is 3.9 percent above the average maximum extent for the 30-year period (1981-2010).
However, keep in mind that this year's Arctic sea ice extent minimum is 30 percent below what was experienced back in the 1980's. Thus, the percentage loss in the Arctic is much greater than the gains in the Antarctic.
Here is a nice explanation about Antarctic sea ice from NASA Earth Observatory.
A look at the increase in global ocean heat content.
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