Arctic Ocean now circumnavigable
August 29th, 2010Dr. Jeff Masters at WunderBlog reports that both the Northwest Passage and the Northern Sea Route are now open. Data at the University of Illinois site Cryosphere Today shows it is now possible to completely circumnavigate the Arctic Ocean in ice-free waters – and this will probably continue to be the case for at least a month.
Arctic sea ice extent image for August 24, 2010, as compiled by The University of Illinois Cryosphere Today. The northern route (Western Parry Channel) through the Northwest Passage was completely clear of ice, as was the Northeast Passage. The southern route through the Northwest Passage was still partially blocked.
This year marks the third consecutive year–and the third time in recorded history–that both the Northwest Passage and Northern Sea Route have melted free, according to the National Snow and Ice Data Center.
The Northeast Passage opened for the first time in recorded history in 2005, and the Northwest Passage in 2007. It now appears that the opening of one or both of these northern passages is the new norm.
Here’s an updated graphic:
As this graphic from Chris Mooney’s article in New Scientist shows, ice volume has been decreasing even more precipitously than ice area.
The average volume of Arctic ice between July and September has fallen from 21,000 cubic kilometres in 1979 to 8000 cubic kilometres in 2009, a 55% decline compared with the 1979 to 2000 average. This is even faster than the decline in ice extent, which is 40% below the long-term average.
Not only has the total volume of Arctic ice continued to decline since 2007 considerably more quickly than predicted by most climate models, the rate of loss is accelerating. The Arctic Ocean may soon be essentially ice-free during the summer months. The dark ocean waters, mostly devoid of ice, would then absorb still more sunlight, further warming the overlying atmosphere during an increasingly lengthy ice-free season, reshaping weather throughout the region and well beyond it.