sierraclub.org - sierra magazine - march/april 2012 - before our eyes: shrinking arctic ice
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Before Our Eyes: Shrinking Arctic Ice
The pink line indicates the median sea ice extent for Septembers from 1979 to 2000.
© 2011 Europa Technologies; © MapLink/Tele Atlas; © Google; U.S. Department of State Geographer
(Source: National Snow and Ice Data Center, Sea Ice Index)
Imagine if, in the years since Ronald Reagan launched his successful presidential campaign, 44 percent of the United States had disappeared—1.4 million square miles, an area equivalent to all the states east of Texas. That's how much sea ice has disappeared from the Arctic Ocean since satellites began taking reliable images of the region 32 years ago.
Arctic ice is most extensive in the sunless winter and shrinks to its annual minimum each September. Over the years, that minimum has become increasingly minimal, declining by 40 percent since 1979.
Says Mark Serreze, director of the National Snow and Ice Data Center, "We may be looking at an Arctic Ocean essentially free of summer ice only a few decades from now."
The images at left were taken in September 1979 and September 2011. New research by Jennifer Francis of Rutgers University shows that severe ice loss can slow down the jet stream winds that control much of our weather, resulting in more persistent weather patterns: extended cold spells, droughts, and heat waves. Loss of summer ice is also leading to enormous releases of methane (a greenhouse gas 20 times stronger than carbon dioxide) from the Arctic Ocean seabed, which are likely to hasten the rate of climate change. —Paul Rauber
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