2010 Minimum Artic sea ice.

On September 19, Arctic sea ice reached its 2010 minimum, at 4.60 million square kilometers (1.78 million square miles). The National Snow and Ice Data Center (NSIDC) reported that 2010 Arctic sea ice extent was the third-lowest on the satellite record. (The record low, set in 2007, was 4.13 million square kilometers or 1.59 million square miles.) The 2010 minimum was part of a larger pattern of overall Arctic sea ice decline dating back to at least the early 1970s.

The top image, made from sea ice observations collected by the Advanced Microwave Scanning Radiometer (AMSR-E) Instrument on NASA’s Aquasatellite, shows sea ice extent on September 19, 2010. Ice-covered areas range in color from white (highest concentration) to light blue (lowest concentration). Ocean water is dark blue, and landmasses are dark gray. The yellow outline is the median minimum sea ice extent for 1979–2000; that is, areas that were at least 15 percent ice-covered in at least half the years between 1979 and 2000. Compared to the long-term average, sea ice concentration north of Alaska and eastern Siberia was especially low in 2010.

Arctic sea ice behavior was unusual in 2010 in that the sea ice appeared to reach its minimum extent on September 10 and began growing again. Acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS)on NASA’s Terra satellite, the middle and bottom images capture some of that ice growth, occurring in the East Siberian Sea. The middle image is from September 12, and the bottom image is from September 14. New, thin ice appears in the bottom image as rippled sheets, barely lighter than the underlying ocean water. This is probably nilas—thin sheets of ice with an oily or greasy appearance.

NASA