Difference between revisions of "Arctic"
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Revision as of 15:13, 28 February 2013
Sea Ice loss: isolating effects on polar bears
The first animation shows ASCAT radar imagery from 01 Dec 2012 to 22 Feb 2013. This is single channel radar at 5 Ghz, or grayscale. It could be mixed as an additional channel with Jaxa radar imagery to false-colorize it more informatively.
It shows a block of newish ice (initial yellow outline) pushing down on the multi-year ice and squeezing a good part of it out the Fram Strait (final purple outline). There seems to be good export action out the Bering Strait as well.
It can be seen that the Svalbard region, home of some 4,000 polar bears, has minimal sea ice this winter. This will lead to bears being concentrated in a small area as they cannot hunt seals from pack ice, which in turn will lead to conflicts.
Genetic isolation of the (reduced) bear population would be unfavorable for long-term polar bear survival. Hybridization with brown bears will not preserve the many Arctic adaptations of polar bears. Thus the question revolves in the short term around the extent of sea ice in the summer of 2013.
The second animation shows that this year's breakup of the ice pack in the Beaufort Sea is very unusual for mid-winter, perhaps unprecedented in recent millenia. In the spring of 2012 something rather similar happened but much late, in April.
The animation covers 12 March to 17 June 2012 with Terra satellite visible imagery at 4 km resolution. The event begins above the Bering Straits, but it really takes off on March 22 and by April 9 begins to strongly resemble mid-Feb 2013. On April 17 it has reached its geographic terminus, Banks Island.
If taken as a simplistic predictor of the 2013 melt season, that is 51 days ahead of last season. Early open water will greatly affect polar bears, as well as walrus.
The third animation shows unprecented crack break-up in February. The crack system is spreading eastward at 2 miles an hour and has now hit Banks Island