Low lakes may be blowin' in the wind
By Dave LeMieux CHRONICLE STAFF WRITER
Summer wind speeds over the Great Lakes have been increasing
slightly during the past 25 years, according to National
Oceanic and Atmospheric Administration scientists.
Though slight, the increase could be further proof of
global warming and be contributing to the main force that
takes water from the Great Lakes: evaporation.
Wind direction is changing more frequently as well, said
oceanographer Mike McCormick of NOAA's Great Lakes
Environmental Research Lab in Ann Arbor.
"A lot of climate change signals are very small,
but if they persist over a long time they can have a large
effect," said McCormick. So "it's too soon to
A study of how wind velocity over the Pacific Ocean during
the 1930s contributed to the creation of the Oklahoma
Dust Bowl is an example of the far-reaching effects produced
by small changes in the environment.
Although lower lake levels are one possible result of
increasing wind speeds, there's no direct evidence yet
linking the two, said McCormick. "There's so much
we don't know about climatology. This could be a short-term
McCormick is studying wind data from eight National Data
Buoy Center monitors located in the middle of lakes Michigan,
Superior, Huron and Erie. The buoys were put in place
in response to the 1975 sinking of the Edmund Fitzgerald.
Some scientists have predicted that global warming will
lead to long-term increases in wind speeds. Scientists
studying global warming have shown that excessive amounts
of carbon dioxide and other pollutants from burning coal,
oil and gas have accumulated in the atmosphere. The pollution
traps heat from the sun in the atmosphere, driving up
global temperatures in the same way a greenhouse traps
heat for plants.
Earlier Great Lakes studies have indicated that average
water temperatures in the Great Lakes are going up from
year to year and that the lakes are warming up earlier
and earlier each summer.
"It's really hard to say that these effects are
directly related to climate change," said Gary Fahnenstiel,
director of NOAA Lake Michigan Field Station in Muskegon.
"But they are consistent with what has been predicted
by regional climate change models."
Because of the higher temperatures, the lakes are losing
more water by evaporation than they have in the past.
More evaporation and less rainfall have led to lower lake
levels in the past five years.
Warmer winters have led to little or no ice cover on
the lakes, which means even more evaporation.