Lakefront property owners lose sleep over flood risks. High school students fill sandbags to protect the fragile coastline. America’s Great Lakes, the largest body of freshwater on Earth, are at, or near, historically high levels. That scenario sounds all too familiar to local residents: last month Lake Michigan, the most variable of the Great Lakes, hit its highest levels since records began. But actually, I’m describing 1969, when I was one of the high schoolers happy to be let off lessons to break my back on lugging sandbags, rather than my brain on trigonometry. There was ample angst then, too, about high water and the disappearing coastline. The difference was, no one blamed it on global warming way back then.
Today, climate change is everyone’s go-to explanation. When I walk my dogs on lakeside paths turned to ice rinks by the overflowing water, other dog owners mutter darkly about global warming. When Lake Michigan’s waves crash over Chicago’s famous lakefront hiking trails, the radio anchor fingers climate change. When Lake Superior floods my camper van site in the wilds of the state’s Upper Peninsula, a fellow camper assures me it’s because “Republicans don’t believe in global warming”. But is that really what’s going on? In this presidential election year, and in the deeply liberal corner of the Midwest where I live, questioning the reasons for Great Lakes flooding can be seen as a political act.
Even the experts admit there are contradictory factors at play: “It’s a cycle. The Great Lakes have gone up and down forever and there’s every reason to believe they will continue to do so,” says Richard Norton, who works on Great Lakes coastal management at the University of Michigan’s Taubman College of Architecture and Urban Planning. “The lakes go down just long enough for people to forget that they go up again.” While Prof Norton does not question the evidence of global warming, he confesses it is hard to predict its future effect on lake levels: “In terms of overall water levels, who knows what the impact of climate change will be?” he asks.
Some experts predict that warmer temperatures will lead to more precipitation, thus higher lake levels. They note that last month was the hottest January on Earth since records began, according to the US National Oceanic and Atmospheric Administration.