The extent of the sea ice covering the  Arctic Ocean has shrunk. According to scientists from NASA and the  NASA-supported National Snow and Ice Data Center (NSIDC) in Boulder,  Colo.,the amount is the smallest size ever observed in the three  decades since consistent satellite observations of the polar cap began.

The extent of Arctic sea ice on Aug.  26,as measured by the Special Sensor Microwave/Imager on the U.S.  Defense Meteorological Satellite Program spacecraft and analyzed by NASA  and NSIDC scientists,was 1.58 million square miles (4.1 million square  kilometers),or 27,000 square miles (70,000 square kilometers) below  the Sept. 18,2007,daily extent of 1.61 million square miles (4.17  million square kilometers).

The sea ice cap naturally grows during  the cold Arctic winters and shrinks when temperatures climb in the  spring and summer. But over the last three decades,satellites have  observed a 13 percent decline per decade in the minimum summertime  extent of the sea ice. The thickness of the sea ice cover also continues  to decline.

See the website for more details: http://svs.gsfc.nasa.gov/vis/a000000/a003900/a003977/index.html

"The persistent loss of perennial ice  cover -- ice that survives the melt season -- led to this year's record  summertime retreat,"said Joey Comiso,senior research scientist at  NASA's Goddard Space Flight Center in Greenbelt,Md."Unlike 2007,  temperatures were not unusually warm in the Arctic this summer."

The new record was reached before the  end of the melt season in the Arctic,which usually takes place in mid-  to late-September. Scientists expect to see an even larger loss of sea  ice in the coming weeks.

"In 2007,it was actually much warmer,"  Comiso said."We are losing the thick component of the ice cover. And  if you lose the thick component of the ice cover,the ice in the summer  becomes very vulnerable."

"By itself it's just a number,and  occasionally records are going to get set,"NSIDC research scientist  Walt Meier said about the new record."But in the context of what's  happened in the last several years and throughout the satellite record,  it's an indication that the Arctic sea ice cover is fundamentally  changing."