September 15, 2015
Arctic sea ice shrank to its summer minimum — and fourth-lowest level on record — on Sept. 11, according to data released Tuesday by the National Snow and Ice Data Center.
The lack of ice affects wildlife such as polar bears and walruses and also could be changing weather patterns down here over the U.S.
Sea ice extent on Sept. 11 was measured at 1.7 million square miles, which is 699,000 square miles below the average.
September is the month when Arctic ice reaches its lowest "extent" of the year, toward the end of the Northern Hemisphere summer. Sea ice is frozen ocean water that melts each summer, then refreezes each winter. The refreezing process has now begun, the data center said.
It reaches its largest area in March of each year.
The extent ranked behind 2012 (lowest), 2007 (second lowest), and 2011 (third lowest). Moreover, the nine lowest areas in the satellite era have all occurred in the last nine years.
The amount of summer sea ice in the Arctic has been steadily shrinking over the past few decades, due to man-made global warming, according to the National Oceanic and Atmospheric Administration.
“The dramatic loss of summer sea ice during the warmest year on record is further evidence of our dangerous dependence on fossil fuels," said Margaret Williams of the World Wildlife Fund in an e-mail to USA TODAY. "Dwindling sea ice is a stark reminder of the destruction climate change wages on our most vulnerable wildlife and communities."
While satellite measurements of Arctic sea ice only began in 1979, there are still "reasonably accurate assessments of sea ice going back to 1953 from pre-satellite sources such as ship reports and aircraft reconnaissance," said data center director Mark Serreze in an e-mail to USA TODAY.
"What we have seen this summer reinforces our conclusions that Arctic sea ice extent is in a long-term decline," Serreze added, and that ice-free summers in the Arctic will eventually be a reality.
This could actually be good news for shipping interests, who will find easier navigating through the ice-free waters.