Water flowing from the North Atlantic into the Arctic Ocean is warmer today than at any time in the past 2,000 years, a new study shows.
Nicolas van Nieuwenhove, IFM-Geomar, Kiel A research vessel moving through the Fram Strait northeast of Svalbard. The waters of the Fram Strait, which runs between Greenland and the Arctic archipelago of Svalbard, have warmed by roughly 3.5 degrees Fahrenheit over the past 100 years, the study’s authors said. The water temperatures are about 2.5 degrees higher than during the Medieval Warm Period, a period of elevated warmth between A.D. 900 and 1300.
The findings are another indication that recent global warming is atypical in the context of historical climate fluctuations, said Thomas Marchitto, a paleoclimatologist at the University of Colorado at Boulder and a co-author of the study.
“It doesn’t necessarily prove that the change that we see is man-made, but it does strongly point toward this being an unusual event,” Dr. Marchitto said. “On a scale of 2,000 years, it stands out dramatically as something that does not look natural.”
The scientists used cores of ocean sediment containing fossils of microscopic shelled organisms called foraminifera to reconstruct past water temperatures in the strait. They found that the abundance of a species of warmer-water foraminifera rose sharply in the past 100 years, becoming dominant over a cold-water variety for the first time in 2,000 years.
The scientists also tested the shells for levels of magnesium, which rise in tandem with water temperature.
“Both of those approaches gave us the same answers,” Dr. Marchitto said.
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