SSSSSSSSSSSSSS Today, centuries of human exploitation of the Great Lakes have left a legacy of neglect. Coastal sediments are contaminated with PCBs, mercury, and toxins from old coal-burning power plants, paper mills, and factories. Invasive plants, fish, and other organisms have unsettled natural ecosystems. Many of the original marshes and coastal wetlands that filtered out pollutants and provided spawning grounds for fish have been damaged or destroyed. Untreated sewage from overflowing municipal storm sewers flows directly into the lakes after heavy rains, often making public beaches too dangerous for people to use. President Barack Obama has set aside $475 million in his 2010 budget to clean up and restore the Great Lakes. But with so many long-standing problems to be addressed, it’s hard to know where to begin. LSAmagazine asked three environmental experts what they see as the greatest threat to the Great Lakes and what we should do about it.
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Climate Change Knute Nadelhoffer Director, Biological Station Professor, Ecology and Evolutionary Biology A warming climate created the Great Lakes
around 10,000 years ago. Now, Knute Nadelhoffer worries that rising temperatures caused by the buildup of carbon dioxide and other greenhouse gases in the atmosphere are changing the lakes in fundamental, unpredictable ways. Nadelhoffer spends most of the summer at LSA’s Biological Station near Pellston, Michigan, where he works within a few miles of Lake Michigan and Lake Huron and just a short drive from Lake Superior. He sees the data from scientists conducting
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environmental and ecosystem research at the Biological Station and is convinced that climate change is the most serious long-term threat to the future of the Great Lakes. Scientists who study climate change have data that shows the lakes are getting warmer. Average surface temperatures on Lake Superior — the largest, coldest, and deepest lake — were 2.5 Celsius degrees warmer in 2005 than they were in 1979. Over the last 30 years, winter ice cover has decreased on all five lakes. Less ice in the winter means less protection from dry winter winds that blow across the lakes causing more surface water to evaporate — one reason for the recent recordbreaking low water levels in the upper Great Lakes. “Another factor that affects the lakes, in combination with climate change, is the changing pattern of precipitation we are already experiencing in Michigan,” says Nadelhoffer. “Although the total annual amount of precipitation has remained constant, on average, more rain is falling during storms in spring and early summer. We are seeing many more downpours followed by periods of drought later in the summer. “Rivers flow faster after heavy rains and deliver more sediment and nutrients to the lakes,” he adds. “As the lakes get warmer and more nutrient-rich, they become more vulnerable to invasive species. Disturbed ecosystems provide more opportunities for species adapted to warmer, nutrient-rich conditions to invade and establish themselves.” Nadelhoffer says there’s no question our climate is changing and will continue to get warmer. “In 30 years, Michigan’s climate will be more like that of Missouri or Arkansas today. What we can do is recognize that it’s changing and start proactive planning to deal with it. We need upgraded water treatment and water handling facilities to slow storm water runoff into the lakes after heavy rains and to prevent mixing of sewage and storm water. We need new, more efficient ways to heat and cool homes and buildings. There will be health issues, transportation, and public utility issues, and we need to start preparing for them now.” Most importantly, Nadelhoffer says, we need to find ways to limit, and eventually stop, burning fossil fuels that spew carbon dioxide into the atmosphere. “If we continue to conduct business as usual, it’s going to get much, much warmer.”
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