WASHINGTON — New observations this year about snow, ice and temperatures support the conclusion that the Arctic is unlikely to return to the conditions known in the 20th century — and that's likely to affect the weather in the lower 48 United States.
That was this year's key message in the annual update of the National Oceanic and Atmospheric Administration's Arctic report card, released Thursday. The key points, a video and links to scientific reports by 69 scientists from eight countries are available from NOAA online.
The report card is one way that scientists share information about trends they're seeing in the Arctic as a result of the region's warming cycle: Higher air temperatures melt snow and ice, leaving the ocean and land darker, and they then absorb more solar energy, causing more heating and melting.
In the past year:
— There was a link between changes in the Arctic and the severe cold weather last winter in eastern North America, northern Europe and eastern Asia. Usually, cold air is bottled up in the Arctic, but this year the cold was blown south.
"As we lose more sea ice, we'll probably see more of that," said Jim Overland, an oceanographer with NOAA in Seattle. Many scientists are studying the link, but they don't fully understand it yet, he said.
The unusual shift in weather patterns that brought cold air down from the Arctic has happened only twice before in the last 160 years. Overland said it was "a major surprise. I'd put it right up there with the (record) ice loss in 2007."
— Greenland had its warmest year on record. The largest glacier loss ever observed in Greenland occurred during the summer, when a 110-square-mile chunk of the Petermann Glacier broke away. Other glaciers also shrank, and this ice loss is accelerating.
Predictions about sea level rise will have to be revised upward, said Jason Box, a glaciologist at the Byrd Polar Research Center of the Ohio State University, one of a group of scientists who briefed reporters Thursday.
— It was another low year for sea ice cover. When the ice reached its minimum for the year in September, it was the third lowest year of the past 30 years, the period of satellite records. The three lowest years have been over the last four years.
Jackie Richter-Menge, the chief editor of the report and a research civil engineer at the Cold Regions Research and Engineering Laboratory in Hanover, N.H., said the warming trend made any return to previous Arctic conditions increasingly unlikely, at least in the foreseeable future.
"It's very likely Arctic climate warming will continue and that we'll continue to set records in the years to come," she said.
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