While recent studies have shown that on the whole Arctic sea ice has decreased since the late 1970s, satellite records of sea ice around Antarctica reveal an overall increase in the southern hemisphere ice over the same period. Continued decreases or increases could have substantial impacts on polar climates, because sea ice spreads over a vast area, reflects solar radiation away from the Earth’s surface, and insulates the oceans from the atmosphere.
In a study just published in the Annals of Glaciology, Claire Parkinson of NASA’s Goddard Space Flight Center analyzed the length of the sea ice season throughout the Southern Ocean to obtain trends in sea ice coverage. Parkinson examined 21 years (1979-1999) of Antarctic sea ice satellite records and discovered that, on average, the area where southern sea ice seasons have lengthened by at least one day per year is roughly twice as large as the area where sea ice seasons have shortened by at least one day per year. One day per year equals three weeks over the 21-year period.
“You can see with this dataset that what is happening in the Antarctic is not what would be expected from a straightforward global warming scenario, but a much more complicated set of events,” Parkinson said.
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A friend wrote me with the following comment on this piece:
Just the other day, I read that because of global warming we see a dryer,
hotter Australia, with its normal load of moisture being pushed farther
south into the roaring 60s where it ultimately lands on Antarctica. So, this
is all part of the pattern — localized climate change resulting in
redistribution of Precipitation concurrent with generalized heating. This
mechanism might not have been recognized five years age, the date of NASA piece.
AWT