Alaskan Permafrost Mapped from the Skies
Last week, the Interior Department’s US Geological Survey (USGS) released details about a landmark airborne survey of permafrost in the Yukon Flats of Alaska that yielded some of the most detailed, data-rich maps of permafrost ever generated. Permafrost—frozen ground that remains at or below water’s freezing point for at least two years—accounts for only 0.022% of all water on Earth, but it covers more than 20% of exposed land of Earth’s northern high latitudes (in addition to areas of Antarctica and the Patagonia region), where it plays a potentially important role in climate dynamics.
There are many reasons scientists seek to understand where permafrost is and how it is changing. One reason is that changes in permafrost can impact ground stability, affecting infrastructure such as roads, home foundations, water treatment facilities, and industrial sites. Another is that it changes in response to changes in temperature and water systems, and so is a key indicator of climate change.
But the permafrost-climate connection is a two-way street, in which changes in permafrost can also spur changes in climate. In part that’s because massive stores of carbon are locked up in permafrost. As temperatures rise, permafrost thaws, making these stores of carbon increasingly available for release into the atmosphere—which contributes to warming.
Permafrost surveys are typically conducted on the ground through surface monitoring and borehole measurements—a painstaking process. But the survey published last week was conducted by helicopter by towing an instrument that sends electromagnetic pulses downward and measures how the earth below responds to the pulses.
This information was used to create three-dimensional images of permafrost over larger areas than can be captured by ground-based methods, down to depths of more than 300 feet below the surface. The Yukon Flats of Alaska fall at a critical boundary between areas of continuous permafrost (to the north) and discontinuous permafrost (to the south)—making the region especially important to understanding how permafrost behaves under different conditions.
The study released last week demonstrated that this new airborne technique can complement USGS’s ongoing ground-based efforts and provide critical new information to hydrologists, ecologists, climate scientists, and land managers in the Yukon Flats and elsewhere.
To learn more about the USGS airborne permafrost survey, visit: http://pubs.usgs.gov/of/2011/1304/
To read the full research report, visit: http://pubs.usgs.gov/fs/2011/3133/
To read a brief summary of the latest climate data collated by NASA and the National Oceanic and Atmospheric Administration, click here.
Becky Fried is a policy analyst at OSTP
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