Winter Ice on Lakes, Rivers, Ponds: A Thing of the Past?Click on Title link to view entire article. Thanks to Anne Weinberg, US EPA for the submission.
Records over 150 years show trend toward fewer days of ice cover
Ice cover on northern lakes across the U.S. has formed later each winter.
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January 10, 2008
If you're planning to ice skate on a local lake or river this winter, you may need to think twice, according to scientists John Magnuson, Olaf Jensen and Barbara Benson of the University of Wisconsin at Madison. Their research is funded by the National Science Foundation (NSF).
From sources as diverse as newspaper archives, transportation ledgers and religious observances, the researchers have amassed 150 years of lake and river ice records spanning the Northern Hemisphere. All show a steady trend of fewer days of ice cover.
If the pattern continues, only in Currier and Ives prints will ice skaters twirl across frozen rivers.
The records show that later freezing and earlier ice breakup occurred on lakes and rivers across the Northern Hemisphere from 1846 to 1995. Over those 150 years, said Magnuson, changes in freeze dates averaged 5.8 days per 100 years later, and changes in ice breakup dates averaged 6.5 days per 100 years earlier. The findings translate to increasing air temperatures of about 1.2 degrees Celsius each century.