Satellites show thawing of Alaska's permafrost
Climate warming has begun to etch subtle changes to the Arctic land surface, with satellites unveiling hints about the fate of the Far North permafrost on a grand scale.
One particularly unnerving animation portrays the seasonal deformation of a track of land on Alaska’s North Slope during the summers of 2010 and 2011. Watch the red shift that signals the transformation of frozen ground into squishy muck — a meltdown that then subsides several centimeters as the summer ripens into fall.
In a sense, we might be glimpsing a preview of Earth’s worst climate nightmare.
Once a big chunk of the home planet’s permafrost thaws in earnest, organic material frozen solid for thousands of years will decay and release vast quantities of greenhouse gases into the atmosphere, including an outsized bubble of the super greenhouse gas methane.
“About half of the world’s underground organic carbon is found in northern permafrost regions,” explains this story, posted by the European Space Agency. “This is more than double the amount of carbon in the atmosphere in the form of the greenhouse gases carbon dioxide and methane.”
So these new eye-in-the-sky monitoring techniques have been making the task tracking this slow-motion catastrophe a bit easier and should be continued, the scientists said here.
First a primer. Permafrost is earth that’s remained frozen for at least two consecutive years, and it covers an immense area of the Far North — about 7.2 million square miles by one estimate, (equal to the area of the United States and Canada minus Texas.) Most of it occurs in Alaska, Canada, Siberia and Scandinavia, and there are places beneath your insulated boots where that ice-packed dirt reaches more than 1,000 feet deep.
Within all that cold storage lies an estimated 1,700 billion tons of organic carbon — the frozen remains of animals and plants that have been accumulating in the soil over eons, according to an influential commentary that surveyed 41 permafrost experts and was published last fall in the journal Nature. That’s about four times more than all the carbon spewed by human activity in modern times and twice as much the carbon now present in the air, wrote authors University of Florida researcher Edward Schuur and University of Alaska Fairbanks graduate student Benjamin Abbott.
“There’s more organic carbon in northern soils than there is in all living things combined,” said Abbott in this story from 2011. “It’s kind of mind boggling.”
As a result, the ongoing monitoring of the health of permafrost and the status of its organic cargo has become a critical task for climate change research, with scientists analyzing the impacts of wildfires, ancient carbon releases, gas bubbling up from tundra lakes, the warming of still buried layers, and carbon-belching activities of soil microbes.
But getting good data often requires traveling to remote corners of the Arctic — drilling boreholes, taking measurements and monitoring temperature sensors by the scores. (Take a gander at 28 sites monitored by thePermafrost Laboratory at the University of Alaska Fairbanks.)
Now satellites have been changing the game, according to the ESA story.
“Although permafrost cannot be directly measured from space, factors such as surface temperature, land cover and snow parameters, soil moisture and terrain changes can be captured by satellites.”
Using satellites like ESA’s Envisat can produce “panoptic view” of permafrost from a local to a Circum-Arctic dimension,” the scientists explained.
“Combining field measurements with remote sensing and climate models can advance our understanding of the complex processes in the permafrost region and improve projections of the future climate,” added Hans-Wolfgang Hubberten, head of the Alfred Wegner Institute research unit in Germany and president of the International Permafrost Association.
The results were showcased this winter at a big AWI conference, drawing more than 60 satellite jockeys and permafrost scientists from around the world.
The scientists have posted three different web animations that illustrate signs of thawing permafrost seen from earth-orbiting satellites, and they offer an disconcerting view of a process that may soon accelerate the pace of climate change beyond the reach of human intervention.
Aside from the Alaskan subsidence, the ESA posted an animation of polar freezing during 2007, 2008, 2009 and 2010. (Each year gets its own panel, arrayed side by side in a grid.) A third animation shows how average annual surface temperatures have changed across the Arctic from 2005 to 2009.
To keep up with other developments in permafrost science, check out the Permafrost Laboratory at UAF’s Geophysical Institute. The video of the “The Permafrost Twisted House” by Fairbanks permafrost guru Vladimir Romanovsky is also worth a view, along with other mini-documentaries about permafrost.
Contact Doug O'Harra at doug(at)alaskadispatch.com
Posts
No comments:
Post a Comment