Data show warming will shrink Great Lakes
By Jeff Alexander
Published February 07, 2007
Global warming could lower water levels in Lake Michigan and Lake
Huron by 5 feet over the next century, according to new data generated
for a United Nations study of climate change.
Such a change would disrupt the Great Lakes shipping industry and
threaten the lakes' lucrative sport fishery, according to climate
experts and shipping-industry officials.
Higher air temperatures could eliminate nearly all winter ice cover on
the Great Lakes in the coming decades, which would increase
evaporation of the lakes' water, said Brent Lofgren, a physical
scientist at the National Oceanic and Atmospheric Administration's
Great Lakes Environmental Research Laboratory in Ann Arbor.
``The most extreme scenario is that over the next 100 years, we could
see a 5-foot drop in water levels in lakes Michigan and Huron,''
Lofgren is one of several scientists working on a U.N. study of how
global warming could affect the Great Lakes and other freshwater
ecosystems. Expected to be released in April, the study is a follow-up
to a U.N. report released Friday that said human activities over the
past century have caused global warming.
Lofgren said most scientists agree that global warming will drive down
Great Lakes water levels. But he said it is possible that increased
precipitation in the region, another expected symptom of global
warming, could temper the lowering of lake levels.
A 5-foot drop in Lake Michigan water levels would widen beaches by
about 100 feet, according to hydrologists at the U.S. Army Corps of
Engineers in Detroit.
That would benefit shoreline property owners but cause nightmares for
freighter captains and recreational boaters, who would be forced to
navigate dangerously shallow waters.
``A 5-foot drop in lake levels would be catastrophic for our
industry,'' said Glenn Nekvasil, a spokesman for the Lake Carriers
Association in Cleveland. The group represents freighters that
transport cargo exclusively in the Great Lakes.
Nekvasil said such a dramatic change in lake levels would require
freighters to reduce loads by about 23 percent, which would drive up
the cost of shipping.
The water level in Lake Michigan and Lake Huron currently is 13 inches
below average, and Lake Superior is at its lowest water level since
1926, according to government data. Lakes Michigan and Huron
technically are one lake, separated in name only by the Straits of
Global warming also could exacerbate the recent trend toward warmer
Great Lakes water temperatures. That could hurt cold-water fish
species such as lake trout and salmon, the backbone of a $4.5 billion
Great Lakes sport fishery, Lofgren said.
Lofgren said it is important to remember that predictions of how
global warming will affect the Great Lakes are based on long-term
climate trends. He said there could still be periods of brutally cold
weather and blizzards during future winters, despite the projected
rise in Earth's average surface temperature.
A 2006 study by the Union of Concerned Scientists concluded that
average air temperatures in Michigan would rise by as much as 10
degrees Fahrenheit in the winter and 13 degrees in the summer. Such
changes would shorten winters and lengthen summers in Michigan, said
George Kling, a University of Michigan biology professor who worked on
the Union of Concerned Scientists report.
Kling said global warming is expected to increase precipitation in the
Great Lakes region over the next century. But he said the added
precipitation would occur primarily during winter and spring, when
water levels in the lakes already are at their peak.
Global warming also could devastate some of Michigan's trout streams
and northern boreal forests, which rank among the state's most highly
regarded natural features, Kling said.