The X International Forum

Arctic: today and the future

December 10-12, 2020, SAINT PETERSBURG

Bering Sea winter sea ice reached its minimum in thousands years


Bering Sea winter sea ice reached its minimum in thousands  years

The Bering Sea ice cover during the winters of 2018 and 2019 hit new lows not seen in thousands of years, scientists reported, adding to concerns about the accelerating impact of climate change in the Arctic. Satellite data provides a clear picture of how sea ice has changed over the last four decades in the region between the Arctic and northern Pacific oceans. Beyond that, the only ice records available were those recorded in ship logs and other observations. So scientists turned to peat land, which holds organic compounds from plants dating back millennia, on the remote St. Matthew island off Alaska.

By examining different forms of oxygen molecules trapped in the sediment, the scientists were able to estimate atmospheric and ocean conditions that would have affected rainfall and sea ice over some 5,500 years.

Sea ice builds up again each year during the winter. But the new study suggests that, in the Bering Sea, cold-season ice maximums may also be in decline.

The loss of sea ice is already impacting Arctic wildlife, including walruses, polar bears and seals, with consequences for indigenous communities that rely on hunting for their livelihoods.

Shrinking sea ice also exacerbates warming in the region, as ice is replaced by patches of dark water that absorb solar radiation rather than reflecting it back out of the atmosphere.

“Obviously, if we lose the sea ice you are completely changing the temperatures of the Arctic,” said Julienne Stroeve, a climatologist with National Snow and Ice Data Center at the University of Boulder Colorado not involved in the study. “If you lose it all, you’re going to warm up the region even faster.”

Air temperature wasn’t the only factor found to be affecting sea ice, though. Shifts in ocean and atmospheric circulation linked to climate change have an even bigger impact, said lead author Miriam Jones, a geologist at the U.S. Geological Survey.

“There’s a lot more going on than simply warming temperatures,” Jones said. “We’re seeing a shift in circulation patterns both in the ocean and the atmosphere.”

The study noted that changes in sea ice appeared to lag at least several decades behind changes in atmospheric greenhouse gases. That implies that the recent lows in winter sea ice were a response to greenhouse gas levels decades ago.

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