WASHINGTON The Arctic is warmer than it's been in 2,000 years, even though it should be cooling because of changes in the Earth's orbit that cause the region to get less direct sunlight. Indeed, the Arctic had been cooling for nearly two millennia before reversing course in the last century and starting to warm as human activities added greenhouse gases to the atmosphere. "If it hadn't been for the increase in human-produced greenhouse gases, summer temperatures in the Arctic should have cooled gradually over the last century," said Bette Otto-Bliesner, a National Center for Atmospheric Research scientist and co-author...
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