Global warming is likely to dramatically alter the Great Lakes region in the coming decades, making the world's largest body of fresh water shallower and dirtier while hurting the region's ability to capitalize on its greatest natural resource.
That's the conclusion the Intergovernmental Panel on Climate Change delivered Monday as it released the North America chapter of its much publicized report on the worldwide impact of higher temperatures.
"In the Great Lakes and major river systems, lower levels are likely to exacerbate challenges relating to water quality, navigation, recreation, hydropower generation, water transfers and bi-national relationships," the report said.
In particular, the United Nations-sponsored climate change panel said:
*Falling lake levels are expected to make some docks, harbors and marinas inaccessible while creating new beaches throughout the region.
*Conversely, beach closures will likely increase as the amount of pollutants in the lakes grows more concentrated as the water supply shrinks.
*Municipalities that draw that water from the lakes -- such as Buffalo -- will face increasing water quality problems.
*The lower lake levels will mean that less energy will be produced at the region's hydropower plants, which include the nation's largest: the Niagara Power Project in Lewiston.
*Droughts in other parts of the country could lead to demands that Great Lakes water be diverted to those parched regions.
The scientists who produced the report and environmentalists who reacted to it stressed, however, that almost the entire country will experience similarly dramatic impacts.
"Virtually no area of North America will escape the effects of global warming," said Larry Schweiger, president of the National Wildlife Foundation.
The impact in the Great Lakes region is likely to be just the opposite of the higher waters and storm surges expected along the Atlantic coast, the climate report said.
"Many, but not all, assessments project lower net basin supplies and water levels for the Great Lakes," the report said.
The scientists stopped short of projecting exactly how much shallower the lakes could become. But other scientists have projected that lake levels could fall by as much as five feet over the next century.
And the climate change panel -- which projects a 3.6-degree increase in global temperatures over 100 years -- says any sort of major drop in lake levels would have a dramatic impact on life in the Great Lakes region.
Stephen Schneider, a professor of environmental studies at Stanford University who helped prepare the climate report, said lower lake levels could harm industries that depend on the lakes for their water supply. Both shipping and recreational boating would suffer, and some of the region's canals would have to be dug deeper to remain functional.
Worst of all for the region's residents, however, would be the dirtier water that would be remaining in the lakes.
"We've let a lot of chemicals go into the environment in that part of the world, and it is now reasonably contained in the sediments" at the bottom of the region's lakes and rivers, Schneider said.
Lowering the lake levels makes it more likely that those sediments will be stirred up and contaminate the water, he said. And that's why the climate change panel is concerned that global warming could affect everything from municipal water supplies to beach closings to the safety of eating Great Lake fish.
Terry L. Root, a Stanford biologist, said her colleagues in Michigan worry that global warming will render more of the region's fish inedible.
"The concern they have is that as the lake level drops -- which there is no choice about -- the pollution level is going to be increasing," Root said. "So now you're not supposed to be eating whitefish more than one time a week. They're not sure it will even be safe to do that."
And even though there will be less water in the Great Lakes, there will be far more demand for what's left. That's why the report predicts increasing calls for "diversions" of Great Lakes water.
Water-rich states might find themselves in conflict with parts of the country that are especially parched, said Roger S. Pulwarty of the National Oceanic and Atmospheric Administration, a member of the team that put together the report. The report projects that the Southwest in particular could face water shortages.
The report is a vast undertaking that aims to assess how much climate change has already taken place, how much warmer the planet is likely to get and what can be done to mitigate the damage. In effect, it's the U.N.'s central effort on the climate change issue.
And while the report stresses the devastating impact climate change will have in the poorest parts of the world -- which will be least able to adapt -- the scientists involved in the report stressed that every American has reason to be concerned.
"No one in the United States will escape the impact of climate change," said Patricia Romero Lankao of the National Center for Atmospheric Research.