About 12,000 years ago, at the end of the last Ice Age, massive glaciers covered much of North America. Then the world started to get warmer. The glaciers melted and receded to the north, leaving behind a unique and precious legacy: five enormous Great Lakes containing the world’s largest supply of pure, fresh surface water.
As the glaciers moved out, people moved in. At first, there were small groups of hunter-gatherers, then Native American tribes who grew crops and lived in permanent settlements. Living near the lakes meant easy access to fresh water, fish, and game. A network of connecting lakes and rivers made long-distance travel and trade possible. European explorers, fur traders, and merchants arrived in the Great Lakes area in the 1600s and 1700s, followed by waves of immigrants in the 1800s and early 1900s who cut down the forests, dammed the rivers, and drained the marshes.
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. Three environmental experts were asked what they see as the greatest threat to the Great Lakes and what we should do about it.
Climate Change
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 record-breaking 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.”
People and Lifestyle
For Paul Webb, the biggest threat to the future of the Great Lakes is people. It’s not just the total number of people — about 42 million live in the Great Lakes basin today— but the way they choose to live that’s the problem.” Webb is the Associate Director of the Program in the Environment at the University of Michigan’s College of Literature, Science and Arts and Professor of Ecology and in Evolutionary Biology as well.
“You could have more people, if they walked lightly on the landscape, but we’re not very good at walking lightly on the landscape,” says Webb. Webb describes America today as a “me-first” society that places a high value on individual consumption and short-term gains, while ignoring the growing need for long-term investments in communities or the environment.
As a result, Webb believes people are using natural resources in the Great Lakes basin in away and at a rate that is unsustainable. As an example, he points to the water. “Someone asked me what Michigan should do to make the best use of its water,” Webb says. “My answer had two words: Keep it.”The Great Lakes are so enormous that it’s hard to believe they could someday run out of water, but Webb says it’s not impossible. Central Asia’s Aral Sea, sandwiched in between Kazakhstan to the north and Uzbekistan to the south, has almost disappeared, Webb says, because the water was depleted for irrigation much faster than it could be replenished.
“Think of the Great Lakes water as fossil water —some of it is probably original glacial water,” Webb says. “Although there’s a lot of water, it renews slowly, and the amount we can use sustainably is remarkably small — only about one percent of the total volume.”
Billions of gallons of water are pumped from the Great Lakes every year for use in public water supplies, irrigation, industry, and power plants that generate electricity. As the climate gets warmer, the demand for water will increase and lake levels are likely to fall. Webb worries that “if the price is right,” Great Lakes states might start selling water to drought-stricken areas in the United States.
There is also pollution to consider. The Great Lakes was once flush with factories and employment, but now that the boom is over, many factories stand idle and toxic. In 2008, Congress passed legislation to reauthorize the Great Lakes Legacy Act, originally drafted in 1972, which provides additional funding to clean up hazardous hotspots known as “areas of concern.”
But not all pollution has such clear-cut source points. Sewage, pesticides, and fertilizers are washed into the Great Lakes from multiple venues — including farms, drainage ditches, and yards — each year. And the effects of the runoff, including dead zones in some of the Great Lakes during the summer, can’t easily be scrubbed clean.
Webb and other environmental experts are concerned about the tipping point — the point at which people will push the Great Lakes ecosystem beyond its ability to adapt and recover. Unfortunately, no one knows exactly where that tipping point is. “It could be thousands of years from now; it could be a decade,” says Webb. “It might be that we wise up fast enough to do the right things and avoid it. But we need to get started yesterday and we need to have the will to change. If the problem is people, then people have got to be the solution.”
Invasive Species
Over the years, many plants and animals, including humans, have moved in and set up housekeeping around the Great Lakes. Today, the area is home to at least 342 non-native species, according to a recent report prepared by the U.S.Environmental Protection Agency and EnvironmentCanada.
Some, like zebra mussels and sea lampreys, arrived in ballast water from oceangoing ships, or swam in through rivers and canals. Many plants and grasses were imported for use in gardens, to control erosion or help restore wetlands. Foreign fish were brought in to use as game fish, in aquariums and fish farms. About 10 percent of these newcomers are invasive —meaning they either kill off or crowd out native species — and they are changing the ecosystem of the Great Lakes in fundamental and unforeseen ways.
Deborah Goldberg studies the effects of invasive cattails on coastal areas. Goldberg is the Elzada U. Clover Collegiate Professor and Chair of the Department of Ecology and Evolutionary Biology at the College of Literature, Science and Arts at the University of Michigan. In her research, she has seen how non-native plants can destroy native plant populations. It’s one reason why she considers invasive species to be the greatest threat to the future of the Great Lakes.
The effects of invasive species on the Great Lakes environment are complicated. At first, some of them can even appear to be positive. “With zebra mussels, you get incredibly clear, beautiful water,” Goldberg says. “But they multiply so rapidly, they wipe out all the native mussels. Nonnative cattails are used in constructed wetlands, where they do a great job of cleaning up wastewater, but they can have devastating effects on biodiversity.”
A big part of the problem is that scientists simply don’t know enough about how the ecosystem is changing or what the long-term effects of those changes will be. To find answers, scientists who study environmental and aquatic issues need organization, focus, and a reliable source of funding. “It’s very difficult to get funding for this type of work—even something as simple as setting up a monitoring system to see how fast things are spreading,” Goldberg says.
Goldberg says Michigan is poised to be the leading institution in Great Lakes research. “U-M is right in the middle of the Great Lakes basin,” she says, “and we have the opportunity to bring together scientists from different disciplines who are interested in these pressing issues. Funding for Great Lakes research should continue to be a priority.”Goldberg admits to being pessimistic about our ability to reverse the effects of invasive species on the Great Lakes overall. “There have been so many successive waves of invasive species that have totally changed the aquatic ecosystem and the food web, “she says. “The damage has already been done. We will never get it back to what it was.”
But Goldberg does see potential to make a difference on a local scale, especially when community members, environmental managers, and scientists work together. She is hopeful that “with a lot of money, work, and regulation, we can reduce the rate of new things coming in.”
Sally Pobojewski writes for the University of Michigan. This article was adapted from the LSA Magazine.
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