Warm as the Arctic
Far North off the coast of Greenland is Ellesmere Island, a mountainous, icy patch of earth that supports only one species of woody plant, the tiny, slow-growing Arctic Willow.
The glaciers in this Canadian outpost have been rapidly disintegrating; its main Ward Hunt Ice shelf fractured a couple years ago, while another, the Markham shelf, broke off into the sea.
It’s a great place to study the effects of climate change, both modern and past. Beaver Pond on Ellesmere Island is exceptionally well preserved with peat layers that contain a diverse assemblage of 4 to 5 million year old fossils from a time when the Earth was much warmer than today, and Beaver Pond teeming with life.
Researchers led by the University of Colorado and Canadian Museum of Nature have studied some of these fossils to get a more precise estimate of the Arctic temperature during that time period. It was, of course, warmer than today’s Arctic.
But what’s surprising is that the Arctic temperature was considerably warmer relative to today than global averages. In a paper they published in the most recent journal of Geology, the found that while the average global temperature during the Pliocene was 3.6 to 5.4 degrees Fahrenheit warmer than today, Arctic temperatures may have been a whopping 34 degrees balmier.
“These results indicate that Arctic temperatures may be exceedingly sensitive to anthropogenic CO2 emissions,” the researchers write.
Essentially, tropical temperatures varied a lot less than what was happening in the Arctic. This “reduced temperature gradient” can be explained by a number of mechanisms. Heat transport northward from ocean circulation is one potential warming factor, as are changes in Arctic cloud cover and greater absorption of heat due to less ice and darker waters.
What does this spell for today’s Arctic? The researchers write:
“The Arctic is clearly a bellwether for modern climate change. Arctic temperatures have increased more rapidly in response to anthropogenic greenhouse gas forcing than global temperatures … our results indicate that a significant increase in Arctic temperatures may be imminent in response to current atmospheric CO2 levels.”