Study Finds Epochal Storm Cycles Unrelated to Human-Induced Climate Change
October 25, 2002
Researchers working at lake sites in New York and Vermont have come up with evidence of cycles of powerful storms by examining cores of sediments that have accumulated over 13,000 years. The scientists report in the journal Nature that a new storm cycle may have already started.
The findings are likely to confound efforts to discern whether human alterations of the atmosphere -- particularly a buildup of greenhouse gases -- are increasing the frequency of severe downpours.
- The storm eras in the Northeast peaked 11,900, 9,100, 5,800 and 2,600 years ago -- with each cycle lasting about a millennium or more, separated by calmer periods lasting about 3,000 years.
- The storms were far more powerful than any in recent times, resulting in giant floods -- although such events were sporadic.
- The region appears to have entered a fifth era in which such superstorms are more likely.
- Some of the sediment layers which indicate huge storms are 10 times as thick as the one left by the greatest flood ever recorded in Vermont: the storm of November 1927 -- which killed 84 people, drowned thousands of cows and demolished 1,200 bridges.
The clues from the lakes appear to mesh with evidence of other periods of stormy weather in the North Atlantic, propelled by a pole-girdling wind and pressure pattern called the Arctic oscillation.
The researchers speculated that the storms amounted to an intense burst of precipitation -- with rainfall of several inches an hour lasting a day or two.
Source: Andrew C. Revkin, "Study Finds Storm Cycles Etched in Lake Beds," New York Times, October 25, 2002.
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