Sea ice covering the Arctic Ocean declined last month to the second-lowest extent on record, NASA officials said Tuesday.
Satellite data from NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) at the University of Colorado in Boulder showed that the summertime sea ice cover narrowly avoided a new record low, which was attained in 2007.
The Arctic ice cap grows each winter as the sun sets for several months and shrinks each summer as the sun rises higher in the northern sky. Each year the Arctic sea ice reaches its annual minimum extent in September.
The near-record ice-melt followed higher-than-average summer temperatures, but without the unusual weather conditions that contributed to the extreme melt of 2007.
“Atmospheric and oceanic conditions were not as conducive to ice loss this year, but the melt still neared 2007 levels,” said NSIDC scientist Walt Meier.
Joey Comiso, senior scientist at NASA”s Goddard Space Flight Center in Greenbelt, Md., said the continued low minimum sea ice levels fits into the large-scale decline pattern that scientists have watched unfold over the past three decades.
“The sea ice is not only declining, the pace of the decline is becoming more drastic,” Comiso said.
“The older, thicker ice is declining faster than the rest, making for a more vulnerable perennial ice cover.”
Arctic sea ice extent on Sept. 9, the lowest point this year, was 4.33 million square kilometers (1.67 million square miles). Averaged over the month of September, ice extent was 4.61 million square kilometers (1.78 million square miles).
This places 2011 as the second lowest ice extent both for the daily minimum extent and the monthly average. Ice extent was 2.43 million square kilometers (938,000 square miles) below the 1979 to 2000 average.