The Permafrost Tunnel Research Facility, dug in the mid-1960s, allows scientists a three-dimensional look at frozen ground.
Kate Ramsayer/NASA
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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
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Democratic Sen. Doug Jones of Alabama voted to end the shutdown in exchange for a promise the Senate will consider protecting child immigrants brought illegally to the U.S.
Claire Harbage/NPR
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