Is There A Ticking Time Bomb Under The Arctic?
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Northern Alaska, United States |
Just what exactly is permafrost? And what is happening now that it's warming up? To find out, we enter the Arctic Circle's secret world of ice and frozen history.
The Permafrost Tunnel Research Facility, dug in the mid-1960s, allows scientists a three-dimensional look at frozen ground.
Kate Ramsayer/NASA