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Data show warming will shrink Great Lakes

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  • mtneuman@juno.com
    Data show warming will shrink Great Lakes By Jeff Alexander Kalamazoo Gazette Published February 07, 2007 Global warming could lower water levels in Lake
    Message 1 of 1 , Feb 9, 2007
      Data show warming will shrink Great Lakes
      By Jeff Alexander
      Kalamazoo Gazette
      Published February 07, 2007

      Global warming could lower water levels in Lake Michigan and Lake
      Huron by 5 feet over the next century, according to new data generated
      for a United Nations study of climate change.

      Such a change would disrupt the Great Lakes shipping industry and
      threaten the lakes' lucrative sport fishery, according to climate
      experts and shipping-industry officials.

      Higher air temperatures could eliminate nearly all winter ice cover on
      the Great Lakes in the coming decades, which would increase
      evaporation of the lakes' water, said Brent Lofgren, a physical
      scientist at the National Oceanic and Atmospheric Administration's
      Great Lakes Environmental Research Laboratory in Ann Arbor.

      ``The most extreme scenario is that over the next 100 years, we could
      see a 5-foot drop in water levels in lakes Michigan and Huron,''
      Lofgren said.

      Lofgren is one of several scientists working on a U.N. study of how
      global warming could affect the Great Lakes and other freshwater
      ecosystems. Expected to be released in April, the study is a follow-up
      to a U.N. report released Friday that said human activities over the
      past century have caused global warming.

      Lofgren said most scientists agree that global warming will drive down
      Great Lakes water levels. But he said it is possible that increased
      precipitation in the region, another expected symptom of global
      warming, could temper the lowering of lake levels.

      A 5-foot drop in Lake Michigan water levels would widen beaches by
      about 100 feet, according to hydrologists at the U.S. Army Corps of
      Engineers in Detroit.

      That would benefit shoreline property owners but cause nightmares for
      freighter captains and recreational boaters, who would be forced to
      navigate dangerously shallow waters.

      ``A 5-foot drop in lake levels would be catastrophic for our
      industry,'' said Glenn Nekvasil, a spokesman for the Lake Carriers
      Association in Cleveland. The group represents freighters that
      transport cargo exclusively in the Great Lakes.

      Nekvasil said such a dramatic change in lake levels would require
      freighters to reduce loads by about 23 percent, which would drive up
      the cost of shipping.

      The water level in Lake Michigan and Lake Huron currently is 13 inches
      below average, and Lake Superior is at its lowest water level since
      1926, according to government data. Lakes Michigan and Huron
      technically are one lake, separated in name only by the Straits of

      Global warming also could exacerbate the recent trend toward warmer
      Great Lakes water temperatures. That could hurt cold-water fish
      species such as lake trout and salmon, the backbone of a $4.5 billion
      Great Lakes sport fishery, Lofgren said.

      Lofgren said it is important to remember that predictions of how
      global warming will affect the Great Lakes are based on long-term
      climate trends. He said there could still be periods of brutally cold
      weather and blizzards during future winters, despite the projected
      rise in Earth's average surface temperature.

      A 2006 study by the Union of Concerned Scientists concluded that
      average air temperatures in Michigan would rise by as much as 10
      degrees Fahrenheit in the winter and 13 degrees in the summer. Such
      changes would shorten winters and lengthen summers in Michigan, said
      George Kling, a University of Michigan biology professor who worked on
      the Union of Concerned Scientists report.

      Kling said global warming is expected to increase precipitation in the
      Great Lakes region over the next century. But he said the added
      precipitation would occur primarily during winter and spring, when
      water levels in the lakes already are at their peak.

      Global warming also could devastate some of Michigan's trout streams
      and northern boreal forests, which rank among the state's most highly
      regarded natural features, Kling said.
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