Washington — The amount of sea ice covering the Arctic Ocean has diminished to the smallest size recorded in 30 years of consistent satellite observations.

NASA announced the finding August 27 in collaboration with the National Snow and Ice Data Center (NSIDC).

Arctic sea ice has diminished to 4.1 million square kilometers, below the previous record of 4.17 million measured in September 2007.

A summer melt is part of the annual cycle for Arctic sea ice; ice is added to the cap in the frigid Arctic winters. But in recent years, the restoration of ice in winter has not kept pace with the melt-off of the warm season. Satellites have observed a 13 percent decline per decade in the minimum area covered by sea ice. The thickness of the ice sheet is also declining.

“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 Maryland. “Unlike 2007, temperatures were not unusually warm in the Arctic this summer.”

The low is likely to go lower before the end of the 2012 summer. The decline below the 2007 level was observed August 26, the NSIDC reported. Mid- or late September is usually the time when the Arctic sea ice reaches its minimum for the year.

“By itself, it’s just a number, and occasionally records are going to get set,” NSIDC 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."

The data is collected by the U.S. Defense Department’s Meteorological Satellite Program.