On Sept 12, 2009, the extent of sea ice in the Arctic reached the third lowest level ever recorded since satellite records began in 1979. The National Snow and Ice Data Center estimates that the overall extent dropped to 5.1 million square kilometers, well below the average minimum extent of 6.71 million square kilometers (1979-2000). Only 2007 and 2008 have had lower ice extents. The small increase in 2009 was mostly due to ice spreading caused by strong polar winds. Ice concentration and thickness, however, have not increased, making predictions about a rebound in Arctic ice premature at this moment.