Arctic sea ice appears to have stopped melting for the summer, leaving behind the second-greatest expanse of ocean of any year since scientists began measuring, according to a report released this week by the National Snow and Ice Data Center at the University of Colorado. There was slightly more ice-melt last summer, the NSIDC said, but the preliminary 2008 data show nearly 1 million square miles less sea ice than average over the last 30 years.
Despite overall cooler summer temperatures, the 2008 minimum extent is only 390,000 square kilometers (150,000 square miles), or 9.4%, more than the record-setting 2007 minimum. The 2008 minimum extent is 15.0% less than the next-lowest minimum extent set in 2005 and 33.1% less than the average minimum extent from 1979 to 2000.
This season further reinforces the long-term downward trend of sea ice extent.
The scientists emphasized the mid-September results are preliminary, noting that ice continued to contract after temperatures cooled in 2005. Check back here for daily updates, including a map of the sea ice extent and a graph displaying the sea ice area over time.
…NSIDC will issue a formal press release at the beginning of October with full analysis of the possible causes behind this year’s low ice conditions, particularly interesting aspects of the melt season, the set-up going into the important winter growth season ahead, and graphics comparing this year to the long-term record. At that time, we will also know what the monthly average September sea ice extent was in 2008—the measure scientists most often rely on for accurate analysis and comparison over the long-term.
The center’s Web site includes background on sea ice, a Quick Facts on Sea Ice section and an FAQ on how scientists measure the ice and why it’s an important indicator of the acceleration of global warming.