The Arctic Ocean’s ice cover has plummeted to a record low, and with as many as three weeks left in the annual melt season, may continue to shrink.
The area covered by ice declined to 4.10 million square kilometers (1.58 million square miles), the average of five consecutive days through yesterday, according to data compiled by the U.S. National Snow and Ice Data Center in Boulder, Colorado. The previous low was 4.17 million square kilometers in September 2007, based on satellite records dating to 1979.
The ice cap is shrinking at a record pace this year, one of the most visible signs of climate change, according to Walt Meier, a research scientist at the NSIDC. It shrank about 17 percent in the past 11 days. Ice coverage for the five days ending Aug. 15 was 4.93 million square kilometers.
“We’ve lost over a million square kilometers in the last few weeks,” Meier said today on a conference call. “I would definitely bet we’d go below 4 million square kilometers in the next few days and that’s never been seen before in our satellite records.”
The average annual minimum area from 1979 to 2010 was 6.29 million square kilometers. Arctic temperatures from June through mid-August were 2 degrees Celsius (3.6 degrees Fahrenheit) to 3 degrees Celsius warmer than in a typical year.
“It used to be that the Arctic ice cover was a huge block of ice -- it melted from the edges -- but now it’s more like crushed ice,” he said. “Parts of the Arctic have become like a giant slushy.”
Sea ice melts every summer and typically starts to freeze again in September. The NSIDC uses five-day averages when calculating measurements to account for day-to-day anomalies. Oceans with less ice reflect less sunlight, exacerbating rising temperatures.
“The ice cover gets more and more vulnerable to these extreme conditions,” Meier said. “The Arctic has become like a fighter with a glass jaw.”