scoff at dry forecast
University prediction of Great Lakes' drought draws criticism
Joel Kurth / The Detroit News
January 25, 2002
at a glance
Research at Indiana University could
change the way people think about water levels of
the Great Lakes. Here's a look at the study:
* Going beyond theories that lakes
rise and fall in 30-year cycles, specialists have
tracked the lakes' movements for 4,700 years and see
160-year patterns that more accurately reflect ebbs
* Historical data suggest that the
lakes now are at the end of an 80-year rise and will
begin to fall for another 80 years, until their lowest
level occurs toward the end of the century.
Source: Indiana Geological Survey, sedimentologist
Todd A. Thompson.
BLOOMINGTON, Ind. -- An Indiana
University study is raising interest -- and hackles -- by
predicting that the Great Lakes are on the verge of a history-making
Bucking conventional wisdom that the five-lake
system follows a 30-year cycle of ebbs and flows, sedimentologist
Todd A. Thompson argues that detailed erosion studies show
those cycles are just blips in larger, 160-year patterns
of lake levels.
Skeptics balk at Thompson's prediction
that water levels in the Great Lakes will rebound for about
four years, then plunge for 80 more until they reach a nadir
around 2080, when conditions will replicate the Dust Bowl
of the 1930s.
If Thompson's model proves true, Lake
Michigan would drop another 12 inches to close out the century.
"He's going out on a very thin limb predicting
when this will occur," said Roger Gauthier, acting chief
of the U.S. Army Corps of Engineers' Great Lakes Hydraulics
and Hydrology Office in Detroit.
Great Lakes predictions are tough, since
data about their water levels go back only 150 years --
a mere bat of the eye, since the current configuration of
the lakes began forming 3,800 years ago.
Furthermore, most who study the lakes
have seen only high water during their careers.
At the Indiana Geological Survey, Thompson
created a model of Lake Michigan's rise and fall over 4,700
years by studying erosion and shore deposits. He's working
on a similar model for Lake Superior.
"I certainly am going out on a limb, but
what do you do? Collect all your data, then ignore it?"
Thompson said. "Slowly but surely, the lakes are going to
Adding to the complicated equation is
the specter of global warming, which could throw off Thompson's
model and prognosticators who follow the 30-year rule for
fluctuations. And there's fresh ammunition for true believers
in the global warming theory: Eight of 10 of the warmest
years on record have occurred in the last decade -- including
2001, the second-hottest ever.
"If our more excitable friends and colleagues
are right and the globe is warming, then all bets are off"
for predicting lakes, said Chuck Pistis, a Lake Michigan
specialist from Grand Haven.
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