This map of the Arctic shows how earlier melt onset (left), and later freeze onset (middle), have contributed to longer melt season (right), over the past 30 years. Image and credit: NASA Earth Observatory.
We've all heard about the extent to which Arctic sea ice is melting every summer, and how the thickness of multiyear ice is declining. Well, some new research from NASA, published in the Journal of Geophysical Research - Oceans, shows that the length of the summer ice-melt season lasts on average some 20 days longer than it did in the 1980s.Though both the onset of melting and the beginning of freeze-up contribute to the lengthening season the scientists say it is really autumn freeze-up that it the bigger factor. More open water at the end of the summer, combined with warmer autumn temperatures, mean that freezing begins on average four days later each year.
The areas with the greatest increase in melt days per decade are seen in Hudson Bay, the East Greenland Sea, the East Siberian Sea and the Chukchi/Beaufort Sea.
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