The National Snow and Ice Data Center reported Monday that in the first 10 days of August, Arctic sea ice extent declined one million kilometers. Sea ice is now disappearing on a daily basis nearly 50 percent faster than it typically does this time of year.
So the race is on again to see whether 2008 can repeat -- or beat -- the record set only last year. The NSIDC explains exactly what is going on in the Arctic this summer:
Ice extent has begun to decline sharply. The decline rate surged to -113,000 square kilometers per day on August 7 and as of August 10 was -103,000 square kilometers per day. This compares to the long-term average decline of -76,000 square kilometers per day for this time of year. Normally, the peak decline rate is in early July.
Many of the areas now seeing a rapid retreat saw an early melt onset (see July 2, 2008); this helped set the stage for rapid retreat (July 17 and April 7). However, the more fundamental issue is that these regions started the melt season covered with thin first-year ice, which is especially vulnerable to melting out completely. Thin ice is also vulnerable to breakup by winds; the last ten days have seen a windy, stormy pattern that has accelerated the ice loss.
I'm still happy to take bets on ice-free Arctic by 2020 -- more than half a century earlier than virtually every model has been predicting.
(h/t to Johnny Rook's Climaticide Chronicles)
This post was created for ClimateProgress.org, a project of the Center for American Progress Action Fund.
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Comments
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sindark Posted 12:27 am
13 Aug 2008
Whether it is ice or energy under consideration, the general lesson of shifting baselines is pertinent. We need to see past short term trends and our focus on how the recent past and the present compare, looking onwards to fundamental forces and long-term developments. Of course, when it comes to systems as massive and complex as the global climatic and economic systems, doing so is enormously difficult.
a sibilant intake of breath
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Bob Wallace Posted 3:05 am
13 Aug 2008
Look at the slope of the 2008 melt. It took a significant downturn in mid July.
And remember that 2008 is melting thin ice, new ice that formed after the 2007 melt.
Unless the rate of melting slows soon we should meet or exceed 2007 melting.
Even if 2008 melting slows and doesn't reach 2007 levels I don't think deniers can get much mileage in calling 2007 abnormal.
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Bob Wallace Posted 3:28 am
13 Aug 2008
Look at the slope of the 2008 melt. It took a significant downturn in mid July.
And remember that 2008 is melting thin ice, new ice that formed after the 2007 melt.
Unless the rate of melting slows soon we should meet or exceed 2007 melting.
Even if 2008 melting slows and doesn't reach 2007 levels I don't think deniers can get much mileage in calling 2007 abnormal.
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amazingdrx Posted 3:48 am
13 Aug 2008
http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin
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sindark Posted 6:30 am
13 Aug 2008
From what I have read, probably not. When people talk about disrupting the thermohaline circulation (THC), they are usually talking about large-scale melting of the Greenland glaciers, not the summer disappearance of the Arctic icecap. That being said, nobody really knows where the threshold for seriously disrupting the THC lies.
a sibilant intake of breath
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Bob B Posted 4:41 am
15 Aug 2008
Take a look at this data:
http://img79.imageshack.us/img79/5952/seaiceextentri5.jpg ...
Or you can read here:
http://wattsupwiththat.wordpress.com/2008/08/15/arctic-ic ...
No way will 2008 be like 2007
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MAD MAC Posted 3:45 pm
15 Aug 2008
Victory in Pattani
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amazingdrx Posted 4:03 pm
15 Aug 2008
I wonder if any Greenland ice melt estimates take this into account. These would seem to be exponential phenomena.
http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin
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amazingdrx Posted 3:29 am
17 Aug 2008
"Warmer temperatures are also accelerating ice melt on the nearby Greenland ice sheet, which contains enough ice to raise sea level by seven meters (23 feet). Mass loss in Greenland more than doubled between 1996 and 2005, with loss in the southeast accelerating even further since 2004. The summer of 2007 saw a record area of ice melt on Greenland, 10 percent more than the previous maximum in 2005."
"In 2006, scientists reported that "glacial earthquakes" caused by large masses of ice moving rapidly over bedrock had doubled in frequency in Greenland over the last five years. These earthquakes are associated with meltwater from the glacier surface, which flows to the base of the ice sheet and lubricates it, causing rapid glacial movement. Positive feedback mechanisms such as this meltwater lubrication accelerate the speed with which glaciers react to warmer temperatures; ice sheets once thought to change only over millennia are now seen to be responding to warmer temperatures"
This seems to indicate they are connected. That the warmer water at the edge of Greenland glaciers where icebergs calve and the higher rainfall from warmer arctic temps, both cause the dobins (glacial lakes) at the edge of glaciers to increase.
Eventually these lakes drain into cracks in the glacier and lubricate the sliding effect at ground level under the glacier. The increase in the speed of the slide of the glacier connects the warming arctic sea temperature to the glacial melt.
Warmer water at the edge of the glacier causes icebergs to break off quicker too and melt out through the fijords instead of clogging them up and slowing the glacier down.
I think this in turn, dooms the Gulf Stream to end shortly after arctic ice vanishes.
http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin
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