Arctic sea ice continues on downward path

U. COLORADO (US)—The Arctic sea ice cover appears to have reached its minimum extent for the year, the third-lowest recorded since satellites began measuring sea ice extent in 1979.

While this year’s September minimum extent was greater than 2007 and 2008, the two record-setting and near-record-setting low years, it is still significantly below the long-term average and well outside the range of natural climate variability.

Most researchers believe the shrinking Arctic sea ice is tied to warming temperatures caused by an increase in human-produced greenhouse gases being pumped into Earth’s atmosphere.

The sea ice extent dropped to 1.84 million square miles, or 4.76 million square kilometers on Sept. 10.

It is likely the lowest ice extent of the year as sea ice appears to have begun its annual cycle of growth.

The 2010 minimum ice extent is 93,000 square miles, or 240,000 square kilometers, above the 2008 numbers and 240,000 square miles, or 630,000 square kilometers, above the record low in 2007.

The 2010 sea ice extent is 130,000 square miles, or 340,000 square kilometers, below 2009.

“We are still looking at summers with an ice-free Arctic Ocean in perhaps 20 to 30 years,” says Mark Serreze, professor of geography at the University of Colorado at Boulder.

The 2010 minimum is 753,000 square miles, or 1.95 million square kilometers, below the 1879-2000 average minimum and 625,000 square miles, or 1.62 million square kilometers, below the 1979 to 2010 average minimum.

National Snow and Ice Data Center researchers determine the minimum sea ice extent using a five-day running average, so there is still a small chance the sea ice extent could fall slightly, Serreze says.

More detailed information will be provided in early October with a full analysis of the 2010 Arctic ice conditions, including aspects of the melt season and conditions heading into the winter ice-growth season.

More news from University of Colorado: