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Temperate Forests Could Worsen Global Warming

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  • Pat Neuman
    Temperate Forests Could Worsen Global Warming Stanford CA (SPX) Dec 07, 2005 Growing a forest might sound like a good idea to combat global warming, since
    Message 1 of 1 , Dec 6, 2005
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      Temperate Forests Could Worsen Global Warming


      Stanford CA (SPX) Dec 07, 2005
      Growing a forest might sound like a good idea to combat global
      warming, since trees draw carbon dioxide from the air and release
      cool water from their leaves. But they also absorb sunlight, warming
      the air in the process.
      According to a new study from the Carnegie Institution's Department
      of Global Ecology and Lawrence Livermore National Laboratory,
      planting forests at certain latitudes could make the Earth warmer.
      Carnegie's Ken Caldeira will present the work at the American
      Geophysical Union Fall Meeting in San Francisco on December 7, 2005.

      The researchers used complex climate modeling software to simulate
      changes in forest cover and then examined the effects on global
      climate. Their results were surprising. "We were hoping to find that
      growing forests in the United States would help slow global
      warming," Caldeira said. "But if we are not careful, growing forests
      could make global warming even worse."

      The researchers found that while tropical forests help keep Earth
      cool by evaporating a great deal of water, northern forests tend to
      warm the Earth because they absorb a lot of sunlight without losing
      much moisture. In one simulation, the researchers covered much of
      the northern hemisphere (above 20° latitude) with forests and saw a
      jump in surface air temperature of more than 6° F. Covering the
      entire planet's land mass with trees led to a more modest increase
      of about 2° F.

      When the scientists restricted the simulation to middle latitudes
      such as the continental United States, the picture was not quite so
      clear. At first, cooling due to the uptake of carbon dioxide would
      offset warming from sunlight absorption. But after several decades,
      carbon dioxide would begin diffusing from the ocean into the
      atmosphere, diminishing the cooling effect and warming the Earth in
      the long term.

      Caldeira warns against planting forests on abandoned croplands as a
      strategy to combat global warming, which some have recommended. But
      he also recognizes the importance of forests.

      "I like forests. They provide good habitats for plants and animals,
      and tropical forests are good for climate, so we should be
      particularly careful to preserve them," Caldeira commented. "But in
      terms of climate change, we should focus our efforts on things that
      can really make a difference, like improving efficiency and
      developing new sources of clean energy."

      Related Links
      The Carnegie Institution of Washington


      http://www.terradaily.com/news/climate-05zzzzzzv.html
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