(Washington) Winter ice in the Bering Sea, in the northern Pacific Ocean between Alaska and Russia, has never diminished like this in 5,500 years, according to a study released Wednesday from a single core of peat sourced from an island.
Posted September 2, 2020 at 2:30 PM
France Media Agency
The team of researchers analyzed the vegetation accumulated on the uninhabited island of St. Matthew over 5,500 years, including variations over time (and peat layers) of two types of oxygen, isotopes 16 and 18, the proportions of which are correlated with atmospheric and oceanic changes and fallout.
The 1.45 meter long core, taken in 2012, represents 5,500 years of accumulation.
“This tiny island in the middle of the Bering Sea has de facto recorded what happened in the ocean and the atmosphere around it,” said Miriam Jones, the researcher who studies the study at the University of Alaska and subsequently at the American Bureau of Geological Research. .
The ice in the Arctic and Bering Sea melts in summer and reforms in winter, but satellite observations date back to 1979. The significance of this new analysis, published by the journal Science Advances, is to go back much further.
For the Arctic, the decline of winter ice in recent decades has been clear and rapid, in parallel with warming and the increase in the CO2 concentration in the atmosphere.
But the Bering Sea seemed stable over the decades, the study authors write, with the exception of 2018 and 2019, when a sharp decline was observed. The question then was whether this was an anomaly or a trend.
“What we have recently observed is unprecedented over the past 5,500 years,” writes Matthew Wooller, director of the Alaska Stable Isotope Facility, who participated in the analysis.
At this rate, the conditions are now conducive to a completely ‘ice-free’ Bering Sea, the authors conclude, with chain implications for the ecosystem.