Analysis of satellite data by NASA and the NASA-supported National Snow and Ice Data Center at the University of Colorado in Boulder indicated the sea ice extent was 1.32 million square miles on Sept. 16.
That is almost 300,000 square miles less than the previous lowest extent seen since satellite measurements began. A total of 1.61 million square miles of coverage were recorded in September 2007, NASA reported Thursday.
Although Sept. 16 seems to mark the 2012 annual minimum, there's still time for winds to change and compact ice floes, potentially further reducing the sea ice extent, NSIDC researchers said.
The sea ice minimum summertime extent has been decreasing over the last three decades as arctic ocean and air temperatures have increased, researchers said.
"Climate models have predicted a retreat of the arctic sea ice; but the actual retreat has proven to be much more rapid than the predictions," said Claire Parkinson, a climate scientist at NASA Goddard Space Flight Center in Greenbelt, Md. "There continues to be considerable inter-annual variability in the sea ice cover, but the long-term retreat is quite apparent."