Every winter, the Arctic Ocean’s sea ice cover reaches a peak and then declines with the onset of spring. That peak, recorded this year on Thursday, was the lowest seen in 37 years of record keeping, federal scientists said yesterday.
Sea ice covered just 5.6 million square miles of the Arctic Ocean on Thursday, about 5,000 square miles less than the previous record set last year, according to the National Snow and Ice Data Center (NSIDC) and NASA. The 1981-2010 average sea ice extent was 6 million square miles.
The Arctic is a portent for climate change, as it is warming at a faster rate than the rest of the planet. Some scientists think the loss of sea ice during wintertime leads to atmospheric “waves” that propel the polar vortex into the Lower 48 states (ClimateWire, Aug. 18, 2014). Between 1975 and 2012, sea ice in the central Arctic Basin has thinned by 65 percent, according to a study published in Cryosphere in February last year.
“The Arctic is in crisis,” Ted Scambos, a glaciologist at NSIDC, said in a statement. “Year by year, it’s slipping into a new state, and it’s hard to see how that won’t have an effect on weather throughout the Northern Hemisphere.”
The record low sea ice levels were triggered by a “warm, crazy winter,” said Mark Serreze, director of NSIDC, in a statement. “The heat was relentless.”
Temperatures over the Arctic Ocean between December and February were an unprecedented 4 to 11 degrees Fahrenheit higher than normal, particularly around the edges where the ice is thin.
Alaska witnessed the third consecutive winter to be significantly warmer than average, and the winter was the driest on record in parts of the state, Rick Thoman, climate science and services manager at the National Oceanic and Atmospheric Administration’s National Weather Service, said in a press briefing last month.
“Mark Twain said, ‘Climate’s what you expect; weather is what you get,’” he said. “This winter has not brought much of what we expect to Alaska.”
The ‘unraveling of the Arctic’
El Niño, which elevated temperatures around the world, might have played some role in the Arctic’s unusual warmth, said Jennifer Francis, a climate scientist at Rutgers University. She pointed to the atmospheric circulation system as a possible culprit, as well.
A cold blob of water has persisted in the north Atlantic Ocean, and it has consistently pushed storms into Europe, she said. As a side effect, pulses of heat and moisture from these storms have sometimes traveled as far as the North Pole. This may have slowed ice formation and pushed the ice edge northward, she said.
Other scientists pointed to warming oceans as a potential cause. The ice extent was below average in the Barents Sea due to an influx of warm Atlantic Ocean waters from the Norwegian Sea, said Ingrid Onarheim, an oceanographer at the Bjerknes Centre for Climate Research in Norway.
This region is keenly watched by scientists who expect the ocean’s heat conveyor belt, the Atlantic Meridional Overturning Circulation, which transports heat from the tropics to the tip of Greenland, to slow down due to climate change. This would stop the influx of warm waters and lead to a temporary recovery of the wintertime sea ice extent, said Julienne Stroeve, a climate scientist at NSIDC.
Whatever the cause, the new sea ice low is a signal of significant shifts in northern latitudes, said Rafe Pomerance, former deputy assistant secretary of State and chairman of Arctic 21, a coalition of nongovernmental organizations concerned with climate change in the region.
“Not only is the sea ice in steep decline, but snow cover in spring in the Northern Hemisphere, permafrost is thawing, we are losing the Canadian and Alaskan glaciers, and Greenland is shrinking,” he said. “It is a signal of the continuing unraveling of the Arctic.”
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500