In the past few days, the Arctic sea ice has reached it’s lowest point in the satellite ice measuring era (30 some years). This trend of lower summer sea ice levels is nothing new. In fact the six lowest Arctic sea ice extents have occurred basically in the last six years (2007 through 2012). As of mid August, an area roughly the size of South Carolina was melting each day. The highest Arctic sea ice extent during the satellite record occurred in 1980. What’s interesting when comparing the previous low in 2007 to the new one in 2012 is the different types of weather. It was very warm in the arctic in the summer of 2007. It has not been especially warm there this summer. Apparently we have lost enough of the thick, multi-year ice such that even average summer temperature and wind conditions can cause rapid melting of the remaining ice now.
Sea ice extent fell to 4.10 million square kilometers (1.58 million square miles) on August 26, 2012. This was 70,000 square kilometers (27,000 square miles) below the September 18, 2007 daily extent of 4.17 million square kilometers (1.61 million square miles).
National Snow and Ice Data Center scientist Walt Meier said, “By itself it’s just a number, and occasionally records are going to get set. But in the context of what’s happened in the last several years and throughout the satellite record, it’s an indication that the Arctic sea ice cover is fundamentally changing.”
According to NSIDC Director Mark Serreze, “The previous record, set in 2007, occurred because of near perfect summer weather for melting ice. Apart from one big storm in early August, weather patterns this year were unremarkable. The ice is so thin and weak now, it doesn’t matter how the winds blow.”
“The Arctic used to be dominated by multiyear ice, or ice that stayed around for several years,” Meier said. “Now it’s becoming more of a seasonal ice cover and large areas are now prone to melting out in summer.”
With two to three weeks left in the melt season, NSIDC scientists anticipate that the minimum ice extent could fall even lower.
In 2007, Arctic sea ice extent reached an all-time low in the satellite record that began in 1979. Arctic sea ice follows an annual cycle of melting through the warm summer months and refreezing in the winter. While Arctic sea ice extent varies from year to year because of changeable weather conditions, ice extent has shown a dramatic overall decline over the past thirty years. The pronounced decline in summer Arctic sea ice over the last decade is considered a strong signal of long-term climate warming.
NSIDC will release a full analysis of the melt season in early October, once monthly data are available for September.
For the full announcement and to download data images and maps, see NSIDC’s Arctic Sea Ice News and Analysis page (http://nsidc.org/arcticseaicenews).
See NASA’s news release Arctic Sea ice Shrinks to New Low in Satellite Era.