The Arctic has turned out to be much more sensitive to global climate change than had previously been thought. Studies of sediments from the bottom of Lake Elgygytgyn in Chukotka, conducted by an international team of researchers, have revealed two “super” interglacial warming periods that took place above the Arctic Circle. The scientists also discovered a clear interaction between the Arctic weather and melting of the ice in Antarctica. Their findings were published in the latest issue of Science magazine.
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In the Chukchi language “elgygytgyn” means “white.” The researchers adopted a shorter name for it, “Lake E.” The lake is a deep, circular bowl, surrounded by a ring of low hills. The lake developed at the site of what scientists say is most likely the impact crater from a large meteor strike over 2.8 million years ago. The meteorite fell in a convenient location for scientists, because it is one of the few places in the Arctic that is not glacier, so the lake-bottom sediments have accumulated, undisturbed. By drilling into the lake bottom and studying the cores, scientists reached thirty times deeper into the past than they could with ice cores from Greenland, which can reveal approximately the past 110,000 years.
After studying the makeup of the lake-bottom sediments and the rate at which they were formed, as well as the plant remains inside them, scientists concluded that, in addition to the already known periods of warming 12,000 and 125,000 years ago, this area experienced very strong interglacial warming periods 400,000 and 1.1 million years ago.
Russian lake Elgygytgyn, located 100 kilometers, or 62 miles, north of the Arctic Circle. Source: Arctic Climate Impact Assessment
Computer modeling showed the scientists that such marked climate change cannot be explained either by changes in the rotation of Earth’s axis or by the greenhouse effect. The researchers believe that some additional, as yet unidentified factor was at work. The most probable explanation for the effect is that Antarctica may have “warmed up” the Arctic.
Scientists discovered a clear interaction between the Arctic weather and melting of the ice in Antarctica. Pictured: Martin Melles of Germany's University of Cologne, Julie Brigham-Grette of the University of Massachusetts, and Pavel Minyuk of Russia's Academy of Science. Source: Lake E Project
An earlier international program called ANDRILL discovered that the West Antarctic Ice Sheet has undergone periodic melting in the past.
Some of these melting periods correlate very well with the periods of strong warming in the Arctic.
It is not yet clear how the South Pole affected the North’s weather. Scientists hope to test two possible scenarios for this “interpolar feedback.” One of them suggests that the shrinkage of the ice sheet and disappearance of ice shelves could have reduced the amount of cold bottom water masses flowing into the North Pacific Ocean. This resulted in warmer surface waters, higher temperatures, and increased precipitation on the landmass around the ocean.
A second scenario is that the melting of the West Antarctic ice sheet caused the global sea level to rise and allowed warm waters to reach the Arctic Ocean through the Bering Strait.
Possibly both scenarios were at work, although the extent to which each of them influenced the Arctic climate is not yet clear. What scientists do know is that the Arctic’s sensitivity to interglacial warming has been significantly underrated until now.