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The Snowball Effect of Global WarmingBy

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  • Mike Neuman
    The Snowball Effect of Global Warming By Robert Roy Britt LiveScience Managing Editor posted: 06 September 2005 09:46 am ET In a twist to the proverbial
    Message 1 of 1 , Sep 7, 2005
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      The Snowball Effect of Global Warming
      By Robert Roy Britt
      LiveScience Managing Editor
      posted: 06 September 2005
      09:46 am ET

      In a twist to the proverbial snowball effect, warmer Arctic
      temperatures are stimulating plant growth, which darkens the
      landscape and causes more sunlight to be absorbed rather than
      reflected.

      The result: Winter heating could increase by 70 percent, according to
      a new study.

      The study examined western Alaska during the winters of 2000 through
      2002. Shrubs and other vegetation became more abundant, the
      researchers found. Because the plants are darker than the tundra that
      typically covers the region, the surface gets darker. The
      study "presents the first evidence that shrub growth could alter the
      winter energy balance of the Arctic and subarctic tundra in a
      substantial way," the scientists announced today.

      The study will be detailed Sept. 7 in the first issue of the Journal
      of Geophysical Research-Biogeosciences, published by the American
      Geophysical Union.

      In areas where shrubs were exposed in mid-winter, melting began
      several weeks earlier in the spring compared to snow-covered terrain.
      Yet the shrubs' branches produced shade that slowed the rate of
      melting, so that the snow melt finished at approximately the same
      time for all the sites examined.

      Matthew Sturm, leader of the study, said warming in the region seems
      to have stimulated shrub growth, which further
      warms the area and creates a feedback effect that can promote higher
      temperatures and even more growth. This feedback could, in turn,
      accelerate increases in the shrubs' range and size, he said.

      The Alaskan tundra covers some 1.5 million square miles (4 million
      square kilometers). "Basically, if tundra is converted to shrubland,
      more solar energy will be absorbed in the winter than before," Sturm
      said. And while previous research has shown that warmer temperatures
      during the Arctic summer enhance shrub growth, "our study is
      important because it suggests that the winter processes could also
      contribute to and amplify the rate of the [growth]."
      http://www.livescience.com/environment/050906_arctic_shrubs.html
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