See the bigger picture of shrinking Arctic sea ice
Know Your Earth 2.0: Sea Ice
NASA satellites have monitored Arctic sea ice since 1978. Starting in 2002, they observed a sharp decline in Arctic sea ice extent.
Layers of frozen seawater, known simply as sea ice, cap the Arctic Ocean. Ice grows dramatically each winter, usually reaching its maximum in March. The ice melts just as dramatically each summer, generally reaching its minimum in September. These images show Arctic sea ice concentration for the month of September 1999, 2003, 2007, and 2010. The yellow outline on each image shows the median sea ice extent observed by satellite sensors from September 1979 through 2000. Extent is the total area in which ice concentration is at least 15 percent. The median is the middle value. Half of the extents over the time period were larger than the line, and half were smaller.
› Larger image
› NASA's Earth Observatory
› National Snow and Ice Data Center
› NASA Goddard's Scientific Visualization Studio