Reuters, Oslo :
Sea ice off Antarctica and in the Arctic is at record lows for this time of year after declining by twice the size of Alaska in a sign of rising global temperatures, climate scientists say.
Against a trend of global warming and a steady retreat of ice at earth’s northern tip, ice floating on the Southern Ocean off Antarctica has tended to expand in recent years.
But now it is shrinking at both ends of the planet, a development alarming scientists and to which a build-up of man-made greenhouse gases, an El Nino weather event that this year unlocked heat from the Pacific Ocean and freak natural swings may all be contributing.
“There are some really crazy things going on,” said Mark Serreze, director of the U.S. National Snow and Ice Data Center (NSIDC) in Boulder, Colorado, saying temperatures in parts of the Arctic were 20 degrees Celsius (36°F) above normal some days in November.
Combined, the extent of polar sea ice on Dec. 4 was about 3.84 million square kilometers (1.48 million square miles) below the 1981-2010 average, according to NSIDC satellite measurements. That is roughly the size of India, or two Alaskas.
Antarctica’s expanding sea ice in many recent years has been a big theme for those who doubt global warming is man-made.
John Turner of the British Antarctic Survey said chilly westerly winds that sweep around the continent, perhaps insulating it from the effects of global warming, were the weakest for November in two decades. That may have let more heat seep south, he said.
A recovery of the high-altitude ozone layer over Antarctica, which led to cooler air over the continent when it was damaged by now-banned industrial chemicals, may also be a factor.
But Turner said it was hard to pinpoint exactly what was happening.
“When we began getting satellite data from 1979 the sea ice started to decrease. Everyone said it was global warming … but then it started to increase again,” he said.
