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More Frequent Heat Waves Linked to Global Warming

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  • Mike Neuman
    More Frequent Heat Waves Linked to Global Warming U.S. and European Researchers Call Long Hot Spells Likely By Juliet Eilperin Washington Post Staff Writer
    Message 1 of 1 , Aug 4, 2006
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      More Frequent Heat Waves Linked to Global Warming
      U.S. and European Researchers Call Long Hot Spells Likely

      By Juliet Eilperin
      Washington Post Staff Writer
      Friday, August 4, 2006; A03

      Heat waves like those that have scorched Europe and the United States
      in recent weeks are becoming more frequent because of global warming,
      say scientists who have studied decades of weather records and
      computer models of past, present and future climate.

      While it is impossible to attribute any one weather event to climate
      change, several recent studies suggest that human-generated emissions
      of heat-trapping gases have produced both higher overall temperatures
      and greater weather variability, which raise the odds of longer, more
      intense heat waves.

      Last week, Paul Della-Marta, a researcher at Switzerland's Federal
      Office of Meteorology and Climatology, presented findings at an
      international conference on climate science in Gwatt, Switzerland,
      showing that since 1880 the duration of heat waves in Western Europe
      has doubled and the number of unusually hot days in the region has
      nearly tripled.

      In a separate 2004 study, researchers at Britain's Hadley Centre for
      Climate Prediction and Research produced computer models showing that
      greenhouse gas emissions had doubled the likelihood of events like
      the lethal 2003 European heat wave, and that by 2040 it is likely
      such heat waves will take place there every other year.

      And researchers at the National Climatic Data Center in Asheville,
      N.C., reported this week that nighttime summer temperatures across
      the country have been unusually high for the past eight years, a
      record streak.

      "It's just incredible, when you look at this thing," said Richard
      Heim, a research meteorologist at the center. He added that only the
      Dust Bowl period of the mid-1930s rivaled recent summers for
      sustained heat levels.

      Drew Shindell, an atmospheric physicist at NASA's Goddard Institute
      for Space Studies who attended Della-Marta's presentation, said the
      European findings are especially significant because they draw on
      long-term surface temperature records.

      "The European records, being so long, make a convincing case that
      we're already seeing changes" in the climate, Shindell said. "This is
      not like 'Centuries from now the ice sheets will melt.' This is 'In a
      few decades it will be dramatically different.' To me, that's

      Kevin E. Trenberth, chief of the climate-analysis branch of the
      National Center for Atmospheric Research in Colorado, said, "There
      are very good reasons to believe that the current U.S. heat wave is
      at least partly caused by global warming."

      Trenberth pointed to a study published in March by the Journal of
      Geophysical Research that showed that for more than 70 percent of the
      land researchers had surveyed worldwide, the number of warm nights
      each year had increased and the number of cold nights had declined,
      between 1951 and 2003. The researchers, led by Hadley Centre
      scientist L.V. Alexander, concluded, "This implies a positive shift
      in the distribution of daily minimum temperature throughout the

      Several researchers said it is hard to draw conclusions about the
      relationship between severe heat waves and climate change because
      heat waves occur less often than other weather events and arise from
      specific weather conditions. The current heat wave, said National
      Weather Service meteorologist Dennis Feltgen, stems from "a large
      persistent area of high pressure in the upper atmosphere" that has
      drifted from the West to the East Coast.

      Nevertheless, most experts said it is important to pay attention to
      the high temperatures that have blanketed the United States and
      Europe over the past few years. Last month the National Oceanic and
      Atmospheric Administration reported that the first six months of 2006
      are the hottest on record in the United States, and last month ranks
      as England's hottest July since recordkeeping began in 1659.

      "The trend lines showing so much hot weather in recent years suggests
      some concern, even if we can't say definitively this is a signal of
      climate change," said Daniel C. Esty, a professor of environmental
      law and policy at Yale University.

      Scientists and public health officials said they are particularly
      worried about an increase in summer nighttime temperatures because
      people tend to recover from excessive heat exposure at night. Joel D.
      Scheraga, national program director for the U.S. Global Change
      Research Program of the Environmental Protection Agency, has
      delivered presentations indicating that with increasing temperatures
      and population growth, deaths from extreme heat or cold could as much
      as triple in major American cities from 1993 to 2050.

      Scheraga said the EPA chart was not a clear prediction, because
      federal, state and local officials are working to better protect
      citizens from the dangers of extreme heat and cold. Nearly 100,000
      people have downloaded the EPA's "Excessive Heat Events Guidebook"
      since it was posted online six weeks ago.

      "These are avoidable deaths. There's an opportunity to save lives,"
      Scheraga said. "With climate change, with warming and an intense
      hydrological cycle, the water cycle, we do in fact expect more
      extremes, more flooding and more heat waves."

      Since mid-July, 179 Americans, most of them Californians, have died
      in the current heat wave; more than 52,000 died during the 2003
      episode in Europe, where air conditioning is less common.

      A group of Swiss researchers including Mark A. Liniger, a senior
      researcher at the Federal Office of Meteorology and Climatology,
      wrote in a 2004 paper in the journal Nature that if the increased
      temperature variability continued, "it would represent a serious
      challenge to adaptive response strategies designed to cope with
      climate change."

      Some climate experts and industry lobbyists, however, question the
      correlation between global warming and heat waves. Konstantin
      Vinnikov, a senior research scientist at the University of Maryland
      at College Park, said he expected climate change to have only a minor
      effect on future scorchers.

      "These are events that have happened in the past and will happen in
      the future. Climate trends related to climate change cannot change it
      too much," Vinnikov said.

      And Bracewell & Giuliani LLP lobbyist Frank V. Maisano, who
      represents coal-fired power plants, sent an e-mail to reporters this
      week noting that more than half of the days with temperatures at or
      above 100 degrees Fahrenheit in the Washington-Baltimore region
      occurred between 1874 and 1934.
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