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February 5, 2013

The Impacts of Rising Seas and Reduced Lake Levels

An expert panel at Shedd Aquarium described the threat of global warming to coastal ecosystems and societies.

In the first Winter Quarter event of CIS’s The World Beyond the Headlines series, three experts spoke about how global climate change affects ecosystem and societal health both in Chicago and across the globe. A capacity crowd filled the Shedd Aquarium auditorium for the January 14 discussion of the social and biological impacts of rising seas and reduced lake levels.

Tara Massad, Henry Chandler Cowles lecturer in Environmental Studies, introduced the speakers and emphasized the timeliness of addressing the issue, which has received renewed attention in the aftermath of Hurricane Sandy and recent record low measurements of Lake Michigan waters.

“It's very important that as a public we understand how we are changing the climate and the effects this has on our coastlines as sea levels rise and, at home, as Lake Michigan recedes,” Massad said.

The first two presentations focused on sea level rise. Recent studies of global warming and glacial melting suggest that average sea levels will rise between two and seven feet within the next century. The new figures, which are significantly higher than the previously adopted estimates of seven inches to two feet, reflect improve measurements of glacial loss – ice is now melting at a rate ten times faster than in the 1990s.

“The science that goes into producing these estimates is constantly becoming more sophisticated,” Massad said, “which is important because these numbers are based on complex physical realities such as thermal expansion, precipitation patterns, glacial dynamics, and ocean currents.”

Ben Strauss is COO of Climate Central, which has spearheaded efforts to effectively present those complexities to the public. The group’s website, ClimateCentral.org, includes an online application to search by location analysis of projected levels, and timelines. and infrastructure analysis. and report for download.

Strauss’s talk focused primarily on the effects of sea rise on U.S. coastlines, beginning with a striking account of the extreme, though temporary, surges caused by Sandy on the shores of New York. Strauss noted that while New York is a highly vulnerable area, more than half of the exposure to rising water levels in the U.S. is in Florida. “The bedrock is porous, like swiss cheese,” Strauss said. “So you can’t build levees. The water flows right under them.”

Global average sea level has increased more than eight inches since 1880, according to Climate Central, and the rise is accelerating. Strauss presented a dramatic series of slides correlating the recent rise of CO2 in the atmosphere with the expansion of oceans and melting of polar ice. The likelihood of once-in-a-century floods occurring in populated coastal areas is another important measure that Strauss said is predicted to rise, as floods push further inland.

“By 2050 people will see water get where they've never seen it get before,” he said. “And that means trouble because [everything] is designed for the levels of last century. They're not designed for this world.”

Alongside careful study of rising sea levels, Massad also pointed to the need for discussion of the societal response to inevitable change. “Beyond the physical science involved in understanding global change and the policy work devoted to climate change mitigation, the fact that environmental change is already in motion regardless of future mitigation, requires us to also consider adaptation to our changing planet,” Massad said.

Anthony Oliver-Smith, Professor of Anthropology at the University of Florida, stressed the importance of distinguishing populations that are specifically vulnerable to sea level change and may be forced to migrate. Some groups that are exposed to environmental changes are not as at risk as others. “Vulnerability is a condition that comes out of societal features,” he said. “Each community faces issues with its own package of social and economic variables. It’s not a mass, global movement.”

Recognizing the specific needs of these vulnerable populations will be critical to efforts to resettle them, Oliver-Smith said. “Obviously we have to adapt,” he said. “But do we only adapt? A lot of climate strategies today are designed to keep us living the way we want to live, but in effect they're treating symptoms, not causes. Fundamentally these causes are not driven by mere exposure [to environmental change], but also by vulnerability.”

The local situation in the Great Lakes presents an entirely different set of challenges, according to Philip Willink, Senior Research Biologist at Shedd Aquarium who studies animal species in and around the Great Lakes region. Recent alarms have sounded about the declining levels of Lake Michigan, which over the past several months have set new records. The U.S. Army Corps of Engineers measured the January 2013 mean water level as 576.02 feet above sea level. The previous lowest monthly mean of 576.05 feet was recorded in March 1964.

Like Strauss, Willink provided a longer view of environmental transformations, pointing to cyclic shifts in lake levels that corresponded to various changes “There were times that this auditorium would have been underwater,” Willink said, noting that there have been six-foot changes in lake levels just over the past century. “What's really catching peoples attention is what's going on in the last few years,” he said.

There are many proposed explanations for the shift in Lake Michigan’s levels, according to Willink, including the reversed flow of the Chicago River, dredging, precipitation, even the subtle slope of the Lake toward the south. But these factors fit within the more stable fluctuations in levels, and don’t alone account for the significant recent drops.

Instead, Willink proposed that evaporation of lake water has had the most dramatic impact, particularly in conjunction with decreased precipitation and higher temperatures. The overall warming of the region reduces ice coverage on the lake in winter months by as much as eighty percent, which in turn accelerates evaporation.

Willink’s research at the Aquarium is focused primarily on endangered species in Illinois and the Great Lakes region. Interestingly, the probable effect of reduced lake levels on the natural ecosystem is less urgently concerning to Willink than might be expected.

“Let’s say the Lake drops nine feet,” Willink said. “Then the overall depth goes from 923 feet to 914 feet. Chances are most animals won’t notice a difference. Lake trout will still be swimming around.”

But Willink cautioned that some areas would be at risk, especially nearshore wetlands. “If levels drop too rapidly, [the wetlands] may not have time to move...toward the water,” he said. “It depends on distance, the rate of change, connected habitats, and dispersal, or the distance the plants and animals have to move.”

Strauss noted that the wetlands present a further asymmetry between the effects of rising seas and lowering lakes. As the ocean coasts press inland, the shore ecosystems will be squeezed out. “The marsh has nowhere to migrate against a city,” he said.

Willink noted the opposite may be true in the Great Lakes. “Nature is change,” he said. “The Great Lakes have been changing over time, the plants and animals have been changing with it. By and large they can adapt with it. But there is one species in particular that has a lot of trouble with change, and that would be people.”

Dredging new harbors for boats, increased cargo shipping traffic, and expensive rebuilding of lakefront communities and tourism, are all costly but expected impacts. “Lake levels are changing, and it’s the people who are being inconvenienced,” Willink said.

In Willink’s view, preparing for this future will require society to embrace the idea of change. “Whether its conservation, management, or civic planning,” he said, “people will have to make a choice: do we let the things in the river die, but let the shipping and sanitation going? We have some time to play with it, but not a lot of time, and it comes down to who really wants what.”

Oliver-Smith applied that sense of urgency to the broader problem of climate change, invoking Carter’s famous comment on how America needs to tackle energy and environmental issues with the “moral equivalent of war. We are now facing something more diffuse, less defined, than an enemy nation -- but in effect a very serious challenge. If we change now, it will be painful. If we wait for things to happen, it will be deadly,” Oliver-Smith said.

Massad, who organized the standing-room only event, said she is hopeful that people will continue to engage these problems as members of local, national, and international communities. “Hopefully,” she said, “with increased awareness we'll begin to take the kind of decisive action the panelists suggested is needed to reduce the impacts of climate change on ecosystems and society.”

The panel was part of CIS’s The World Beyond the Headlines lecture series, and the fourth major public event hosted in partnership with the Shedd Aquarium. The Program on the Global Environment has previously presented panels on Asian carp in the Great Lakes, the invasive cane toad in Australia, and the 2010 BP oil spill in the Gulf of Mexico.

By Thomas Gaulkin