New data indicates the continuation of a long-term decline in summer ice underway since at least 1979. Researchers say roughly half the decline can be attributed to global warming.
While tropical cyclones, as well as record droughts, floods, and wildfires have kept several of the lower 48 states occupied this year, the Arctic appears to be elbowing its way on to 2011's list of extremes.
On Thursday, the extent of summer sea ice in the Arctic Ocean fell to its lowest level for any Sept. 8 since satellites first began to monitor conditions there in 1979, according to researchers at the University of Bremen's Institute of Environmental Physics.
Coming so close to the end of the melt season, the observation holds out the prospect that 2011 could replace 2007 as the toughest year for sea-ice survival at the top of the world.
The dip comes on the heels of a record low for the month of July, and August levels that flirted with the 2007 record but did not quite cross the line, according to the National Snow and Ice Data Center in Boulder, Colo.
The data testify to a long-term decline in summer ice underway since at least 1979. Several factors have contributed to the decline.
Recent work by researchers at the National Center for Atmospheric Research (NCAR) in Boulder suggests that roughly half the decline can be attributed to the effects of global warming. The other half they lay at the doorstep of natural swings in regional wind patterns that can drive ice out of the Arctic and into the North Atlantic.