Images: NASA looks back on 2008
Arctic sea ice declines
For 30 years, NASA has used satellites to observe and record changes to sea ice. NASA and the National Snow and Ice Data Center at the University of Colorado say that in 2008, Arctic sea ice reached the second-lowest level recorded since satellite observations have been possible. The lowest point was recorded in September 2007.
"Based on what we've learned over the last 30 years, we know that the perennial ice cover is now in trouble," said Joey Comiso of NASA's Goddard Space Flight Center in Greenbelt, Md. "You need more than just one winter of cooling for the ice to recover to the average extent observed since the measurements began. But the trend is going the other way. A warming Arctic causes the surface water to get warmer, which delays the onset of freeze up in the winter and leads to a shorter period of ice growth. Without the chance to thicken, sea ice becomes thinner and more vulnerable to continued melt."
This map shows the extent of Arctic sea ice in August 26, 2008. The orange line shows the 1979 to 2000 average extent for that day.
December 19, 2008 3:57 PM PST
Photo by: NASA; National Snow and Ice Data Center
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