wired.co.uk, August 28, 2012
By Liat Clark
The National Snow and Ice Data Centre has confirmed its predictions that the Arctic ice cap would melt to its lowest ever recorded level, announcing that the sea ice is continuing to rapidly melt well beyond the record-breaking low of 2007.
On 26 August 2012 the cap surface area fell to 4.1 million square kilometres, 70,000 square kilometers below a five-day running average of 4.17 million square kilometres in the Arctic summer of 2007. The region typically reaches its seasonal low in mid to late September, suggesting the record could soon be an even more dramatic one.
"It used to be the Arctic ice cover was a kind of big block of ice," explained Walt Meier of the National Snow and Ice Data Centre (NSIDC). "It would melt a little bit from the edges but it was pretty solid. Now it's like crushed ice. At least parts of the Arctic have become like a giant slushie, and that's a lot easier to melt, and melt more quickly."
The NSIDC has been using satellite imaging to record sea ice levels since 1979 and, in collaboration with Nasa and the University of Colorado at Boulder, has been registering a steady decline which it believes is inherently linked to climate change. Since the 70s, the centre has recorded an average decline of Arctic sheet ice of 12 percent per decade.
Michael Mann, director of the Earth System Science Centre at Penn State University and theorist behind the "hockey stick" climate change graph, told AFP the record low should be a wake up call to those not taking the threat seriously.
"I think, unfortunately, this is an example that points more to the worst-case scenario side of things," he said. "There are a number of areas where in fact climate change seems to be proceeding faster and with a greater magnitude than what the models predicted. The sea ice decline is perhaps the most profound of those cautionary tales because the models have basically predicted that we shouldn't see what we're seeing now for several decades."
Shipping companies are presumably calling up potential clients to share the good news, but for most, as Shaye Wolf of the Centre for Biological Diversity told reporters, it is "a profound -- and profoundly depressing -- moment in the history of our planet".
The rapid melt is all the more worrying because, unlike the 2007 record year, it cannot be explained away by atmospheric conditions. In 2007, high and low pressure patterns were responsible for the melt. However in 2012, other than a brief cyclone in August, the melt appears to be largely due to continued and permanent patterns in the make-up of the Arctic cap -- the fact that thick, layers of ice that once made up the cap have been rapidly replaced by young, thin ice that lasts only one or two summers (hence, the slushy effect Meir speaks of). Any contributory weather patterns will ware this area, which now makes up about 80 percent of the total Arctic surface area, far faster.
"In the context of what's happened in the last several years and throughout the satellite record, it's an indication that the Arctic sea ice cover is fundamentally changing," said Meier. "The years from 2007 to 2012 are the six lowest years in terms of Arctic sea ice extent in the satellite record. In the big picture, 2012 is just another year in the sequence of declining sea ice. We have been seeing a trend toward decreasing minimum Arctic sea ice extents for the past 34 years, and there's no reason to believe this trend will change."
To demonstrate just how fast the cap is melting, the NSIDC report explains that the daily melt rate has slowed to about about 75,000 square kilometers per day, "equivalent to the size of the state of South Carolina", a figure that is 35,000 square kilometres higher than the daily average of previous years during the same period.
A recent study published by the University of Reading has suggested the rapid melt is due to a natural variation in climactic conditions, known as the Atlantic Multi-decadal Oscillation (a warming and cooling cycle of the North Atlantic that occurs every 65 to 80 years). The warming phase, it calculates, began in the mid 70s, so would correlate with the rapid melt we have seen since NSIDC launched its research. However, this only accounts for 30 percent of the loss and, it concludes, the rest is down to the human race.
Copyright © 2012 Conde Nast Digital.
This article originally appeared here.
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