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NYTimes.com Article: Global Warming Found to Displace Species

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  • rickrise@earthlink.net
    This article from NYTimes.com has been sent to you by rickrise@earthlink.net. Global Warming Found to Displace Species January 2, 2003 By ANDREW C. REVKIN
    Message 1 of 1 , Jan 2, 2003
      This article from NYTimes.com
      has been sent to you by rickrise@....

      Global Warming Found to Displace Species

      January 2, 2003

      Global warming is forcing species around the world, from
      California starfish to Alpine herbs, to move into new
      ranges or alter habits in ways that could disrupt
      ecosystems, two groups of researchers say.

      The two new studies, by teams at the University of Texas,
      Wesleyan, Stanford and elsewhere, are reported in today's
      issue of the journal Nature. Experts not associated with
      the studies say they provide the clearest portrait yet of a
      biological world driven into accelerating flux by warming
      caused at least in part by human activity.

      Plants and animals have always had to adjust to shifting
      climates. But climate is changing faster now than in recent
      millenniums, and many scientists attribute the pace to
      rising concentrations of heat-trapping greenhouse gases.

      In some cases, species' ranges have shifted 60 miles or
      more in recent decades, mainly toward the poles, according
      to the new analyses. In others, the timing of egg laying,
      migrations and the like has shifted weeks earlier in the
      year, creating the potential to separate species, in both
      time and place, from their needed sources of food.

      One academic not associated with the studies, Dr. Richard
      P. Alley, an expert on past climate shifts who teaches at
      Pennsylvania State University, said that climate had
      changed more abruptly a few times since the last ice age
      and that nature had shifted in response. But, he noted,
      "the preindustrial migrations were made without having to
      worry about cornfields, parking lots and Interstates."

      Citing the new work and studies of past climate shifts, Dr.
      Alley saw particular significance in the expectation that
      animals and plants that rely on one another were likely to
      migrate at different rates. Referring to affected species,
      he said, "You'll have to change what you eat, or rely on
      fewer things to eat, or travel farther to eat, all of which
      have costs."

      The result in coming decades could be substantial
      ecological disruption, local losses of wildlife and
      extinction of some species, the two studies said.

      The authors express their findings with a certainty far
      greater than in the last decade, when many of the same
      researchers contributed to reports on biological effects of
      warming that were published by the Intergovernmental Panel
      on Climate Change, the top international research group on
      the issue.

      The authors of one of the new Nature papers, Dr. Camille
      Parmesan, a biologist at the University of Texas, and Dr.
      Gary Yohe, an economist at Wesleyan University, calculated
      that many ecological changes measured in recent decades had
      a 95 percent chance of being a result of climate warming
      and not some other factor.

      "You're seeing the impact of climate on natural systems
      now," Dr. Yohe said. "It's really important to take that

      Some butterflies have shifted northward in Europe by 30 to
      60 miles or more, with the changes closely matching those
      in average warm-season temperatures, Dr. Parmesan said. The
      researchers were able to rule out other factors - habitat
      destruction, for example - as causes of the changes.

      Some of these changes meshed tightly with variations in
      temperature over time. Dr. Parmesan cited bird studies in
      Britain. There, populations of the great tit adjusted their
      egg laying earlier or later as climate warmed early in the
      20th century, then cooled in midcentury and warmed even
      more sharply after the 1970's.

      Over all, Dr. Parmesan's study found that species' ranges
      were tending to shift toward the poles at some four miles a
      decade and that spring events, like egg laying or trees'
      flowering, were shifting 2.3 days earlier a decade.

      Around Monterey Bay in California, warmer waters have
      caused many invertebrates to shift northward, driving some
      species out of the bay and allowing others to move in from
      the south.

      Authors of both new papers said they were concerned that
      such significant ecological changes had already been
      detected even though global temperatures had risen only
      about one degree in the last century.

      They noted that projections of global warming by 2100
      ranged from 2.5 to 10 degrees above current levels, should
      concentrations of carbon dioxide and other heat-trapping
      gases, which flow mainly from smokestacks and tailpipes,
      continue to rise.

      By comparison, the world took some 18,000 years to climb
      out of the depths of the last ice age and warm some five to
      nine degrees to current conditions.

      "If we're already seeing such dramatic changes" among
      species, "it's really pretty frightening to think what we
      might see in the next 100 years," said Dr. Terry L. Root,
      an ecologist at Stanford University who was the lead author
      of one of the new studies.

      The two teams of researchers used different statistical
      methods to analyze data on hundreds of species, focusing
      mainly on plants and animals that have been carefully
      studied for many decades, like trees, butterflies and
      birds. Both teams found, with very high certainty, a clear
      ecological effect of rising temperatures.

      Several of the researchers said the effects of other,
      simultaneous human actions, like urban expansion and the
      introduction of invasive species, could greatly amplify the
      effects of climate change.

      For example, the quino checkerspot butterfly, an endangered
      species with a small range in northern Mexico and Southern
      California, is being pushed out of Mexico by higher
      temperatures while also being pushed south by growing
      suburban sprawl around Los Angeles and San Diego, Dr.
      Parmesan said.

      "The butterfly is caught between these two major human
      factors - urbanization in the north and warming in the
      south," said Dr. Parmesan, who has spent years studying
      shifting ranges of various checkerspot species.

      Dr. Alley said the studies illustrated the importance of
      conducting much more research to anticipate impending harms
      and devise ways to maintain biological diversity, for
      instance with green "wildlife corridors" linking adjacent
      pockets of habitat.


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