The U.S. Snow and Ice Data Center (NSIDC) says the extent of sea ice fell to only 1.32 million square miles on September 16, which is 50 percent smaller in coverage than the 1979-200 average.
The NASA animation to the right shows the rapid melt during August through September 12, which the space agency says is when it determined was the date of maximum melt.
Sea ice extent maps are derived from data captured by the Scanning Multichannel Microwave Radiometer aboard NASA's Nimbus-7 satellite and the Special Sensor Microwave Imager on multiple satellites from the Defense Meteorological Satellite Program.
While ice is starting to reform and expand again around the north pole as winter sets in, most of the northern summer of 2012 saw a record rate of melting.
In June, the rate of melting averaged between 38,000 and 58,000 square miles per day, which was more than double the long-term average. Scientists say that much of the Arctic is now dominated by thinner ice that is only one winter old.
This makes it far easier to melt than multiyear long-term ice that is disappearing rapidly each year.
Such an unprecedented and startling change in the Arctic is a sign of a fundamental change in climate, according to experts.
“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,” said NSIDC director Mark Serreze.
Full story and image: NASA