In 2007, Arctic summer sea ice reached its lowest extent on record - nearly 25% less than the previous low set in 2005. At the end of each summer, the sea ice cover reaches its minimum extent and what is left is what is called the perennial ice cover which consists mainly of thick multi-year ice floes.

The area of the perennial ice has been steadily decreasing since the satellite record began in 1979, at a rate of about 10% per decade. But the 2007 minimum, reached on September 14, is far below the previous record made in 2005 and is about 38% lower than the climatological average. Such a dramatic loss has implications for ecology, climate and industry as new shipping lanes open.

This visualization shows the annual Arctic sea ice minimum from 1979 to 2007. A graph is overlaid that shows the area in million square kilometers for each year's minimum day. The 'previous record' and the '2007' record are highlighted.

NASA/Goddard Space Flight Center Scientific Visualization Studio. Thanks to Rob Gerston (GSFC) for providing the data.