IMAGE: AL GOLUB/ASSOCIATED PRESS
It's the height of the Arctic melt season — do you know where your ice is?
While Greenland and the Arctic sea ice cover have shown no signs of shattering melt records once again this year, satellite images taken on Friday and during late July provide indications that both land and sea ice will once again wind up well below average by the time the melt season ends in late September.
New satellite imagery from NASA and the National Oceanic and Atmospheric Administration (NOAA) show that wildfire smoke from huge blazes burning in northern Canada and Siberia has been drifting over Arctic land and sea ice in recent days, where it could hasten the seasonal melt. Wildfires burning in British Columbia and the Northern Territories of Canada have shrouded large parts of Canada and northern sections of the U.S. in a pungent milky haze during the past few weeks, with limited visibility noted at airports in Montana and Minnesota in late July, for example.
Wildfire smoke doesn't just limit visibility, however. It also contributes to carbon dioxide emissions that warm the planet, and by depositing soot, or black carbon, on highly reflective snow and ice cover, the smoke can also speed up the melting of land and sea ice.
IMAGE: NOAA
By darkening the snow and ice cover, soot increases the absorption of incoming solar energy, which speeds up the loss of ice. Research from polar scientist Jason Box and others have revealed that the Greenland ice sheet has become progressively darker as the climate has warmed, and that this trend is likely to continue, with a speeding up of the rate of ice melt.
However, the specific reasons for this are still not completely understood, with the primary suspects being rapidly increasing temperatures, soot deposition and other impurities in the ice cover. This is why Box is on the ice sheet right now, gathering data for his crowdfunded "Dark Snow" research project.
IMAGE: NASA MODIS
In 2012, a record area — 97% — of the Greenland ice sheet experienced some melting. The Greenland-wide reflectivity, also known as the "albedo," which measures how efficiently a surface reflects incoming solar radiation, recovered a bit in 2013 after a precipitous drop in the previous decade, according to a report released late last year.
IMAGE: NOAA ARCTIC REPORT CARD
While the loss of Arctic sea ice has far-reaching consequences for human and natural systems, it does not cause sea levels to rise. Instead, the melting of the Greenland ice sheet is the major concern there, since it adds extra water to the oceans. If all of Greenland were to melt tomorrow (something which, in reality, would likely take thousands of years to play out), sea levels would rise by about 23 feet, dooming coastal megacities worldwide.
Scientists studying Greenland's glaciers have observed other worrisome signs that melting is proceeding more rapidly than anticipated a few years ago. For example, a study published in March found that three glaciers holding back a vast ice stream in northeast Greenland, a region thought to be the last bastion of stability in that rapidly warming region, are now thinning and moving more rapidly into the sea. One of the outlet glaciers, which flows into the ocean, receded 12.4 miles in just the past 10 years, the study found.
sorce:http://mashable.com/2014/08/01/wildfire-smoke-sea-ice/
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