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1978Report: Shorter lake and river ice seasons confirm global warming

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  • Mike Neuman
    Jun 3, 2005
      Note date. So why did it take so long for people to believe it?

      Report: Shorter lake and river ice seasons confirm global warming

      Historic river and lake ice records were used to confirm that winter
      seasons are indeed becoming shorter

      September 7, 2000

      MADISON, Wisconsin (CNN) -- Records from riverboat captains, Shinto
      monks and others dating to the 15th century confirm a dramatic
      warming trend in the Earth's recent history, scientists said

      Studying climate observations from dozens of sites in the Northern
      Hemisphere, an international team of researchers concluded that
      temperatures have risen steadily for at least 150 years.
      They compiled data on lake and river ice cover from newspaper
      articles, business journals and individual diaries, some as far back
      as 1443.

      Piecing together a historic portrait, the researchers said the
      Northern Hemisphere has experienced increasingly shorter winter
      seasons since 1840.

      "The thing that makes this catchy is that this is a very simple way
      of looking at what happened over the last 150 years," said John
      Magnuson, lead author of the report, to be published Friday in the
      journal Science.

      "These are direct observations of people. Some were religious people,
      some were fur traders," said Magnuson, a freshwater expert at the
      University of Wisconsin in Madison.

      They include:
      • Holy men in Japan who kept precise records at Lake Suwa, where
      deities were believed to have traveled on surface ice.

      • Clerics in Central Europe who walked a Madonna statue over Lake
      Constance when it first froze each season.

      • Fur traders and riverboat skippers in Canada who measured river

      The records, which also come from the United States, Russia and
      Finland, indicate that lakes and rivers now freeze an average of 8.7
      days later and ice cover begins disintegrating 9.8 days earlier than
      150 years ago.

      The findings are consistent with an increase in air temperatures
      during the time of 1.8 degrees C (almost 4 degrees F). Climate
      records confirm a rise of at least 1 degree C (2 degrees F) over the
      past century.

      The trend corresponds with the rise of the Industrial Revolution. Yet
      significant warming takes place well before its peak, suggesting
      other causes besides greenhouse gas emissions from human activities.

      "These increases are generally consistent with scenarios for
      greenhouse gas-forced climate warming, but they may be related to
      other drivers, such as changes in solar activity," wrote Magnuson and
      his colleagues in Science.