The National Snow and Ice Data Center (NSIDC) is part of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder. NSIDC scientists provide Arctic Sea Ice News & Analysis content, with partial support from NASA.
BOULDER, Colorado—Arctic sea ice cover likely melted to its minimum extent for the year on September 16, according to scientists at the National Snow and Ice Data Center (NSIDC). Sea ice extent fell to 3.41 million square kilometers (1.32 million square miles), now the lowest summer minimum extent in the satellite record.
“We are now in uncharted territory,” said NSIDC Director Mark Serreze. “While we’ve long known that as the planet warms up, changes would be seen first and be most pronounced in the Arctic, few of us were prepared for how rapidly the changes would actually occur.”
Arctic sea ice cover 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 minimum extent in September. This year’s minimum follows a record-breaking summer of low sea ice extents in the Arctic. Sea ice extent fell to 4.10 million square kilometers (1.58 million square miles) on August 26, breaking the lowest extent on record set on September 18, 2007 of 4.17 million square kilometers (1.61 million square miles). On September 4, it fell below 4.00 million square kilometers (1.54 million square miles), another first in the 33-year satellite record.
“The strong late season decline is indicative of how thin the ice cover is,” said NSIDC scientist Walt Meier. “Ice has to be quite thin to continue melting away as the sun goes down and fall approaches.”
NSIDC scientists have observed fundamental changes in the Arctic’s sea ice cover. The Arctic used to be dominated by multiyear ice, or ice that survived through several years. Lately, the Arctic is increasingly characterized by seasonal ice cover and large areas are now prone to completely melt away in summer.
“The later minimum date is somewhat surprising because we expected that the late melt in the Chukchi and East Siberian seas would result in cool surface waters that would quickly refreeze once the atmosphere cooled,” Meier said. “However, ice loss continued north of the Laptev Sea, opening up a gap in the ice cover that reduced extent.”