Lakes Michigan and Huron, which, if viewed as a single body of water, constitute the largest freshwater lake in the world, have been receding in such a way as to leave formerly waterfront property in Georgian Bay and other poverty pockets high and dry.

Climate change is at work.
The rock-solid plug that had kept Lakes Michigan and Huron in place for thousands of years had been turned to mush.

The Army Corps acknowledged that something was amiss, pointing to the relative surface levels between Michigan-Huron and Lake Erie.

Because the two systems are connected, when Michigan-Huron drops, downstream Lake Erie historically dropped similarly. But in recent decades the approximately nine-foot difference in "head" between the two had been shrinking — by as much as a foot, according to the Georgian Bay study. This meant Michigan-Huron and Erie's levels were getting closer.

Other explanations for the shrinking difference between the two systems include shifting weather patterns that sent increased precipitation over Lake Erie, as well as the ongoing, uneven rebound of the earth's crust from the last ice age; the land under the Georgian Bay region is rising in relation to areas to the south.
But attempts to make the St. Clair River shipping channel more productive, and seawalls installed by well-to-do Michiganders building their North Shore estates well north of Detroit have contributed to the problem.  Meanwhile, your tax dollars paid for a scale model of the basin, in order to test a fix that would have put an end to the river scouring the channel bottom, possibly replenishing aquifers far below.  That project was abandoned during an episode of high water in the late 1960s and early 1970s (Milwaukeeans with long memories might recall the kerfuffle over a Hoan Bridge engineered for mean water level becoming too close to the lake for the tallest lakers to get under it.)

During a period of historically low interest rates, a project to restore the channel bottom might make economic sense.  Political sense, less so.
Lana Pollack, the U.S. chairman of the Joint Commission, declined to sign the letter from her commission recommending that the governments explore what it will take to bring lake levels up and instead wrote a dissent arguing that a St. Clair restoration offers only "false hope."

She fears the project will detract the public's attention from what she sees as the real issue — climate change causing increased evaporation. Her husband is Henry Pollack, a University of Michigan scientist and member of the team of climate researchers who shared a 2007 Nobel Prize with former Vice President Al Gore.

While Pollack's fellow commissioners have recommended exploring a system that could allow more water to leave Michigan and Huron in wet years, she said the big lakes are so slow to respond to long-term weather patterns that predicting when to let that water go or when to hold it back could prove impossible.

"Some of the very same people who deny the reality of climate change being caused by our energy choices are the same people who say, 'We want you to fix this,'" Lana Pollack said. "So on the one hand they say mankind is too small to impact Mother Nature — that forces of nature are much stronger than the impacts of man. Yet they somehow turn around and say, 'OK, governments: Put a plug in — engineer something, dredge something, dig out, blow up, modify.' They don't think man is too weak to engineer a fix, but they somehow say we're not responsible for the cause."

University of Wisconsin-Milwaukee meteorologist Paul Roebber agrees controlling flows out the St. Clair could be a complex job, but he believes it is one worth exploring, especially in an era when he expects increased evaporation and precipitation cycles to bring unprecedentedly big swings in water levels.

Roebber isn't worried about preserving fluctuations essential to wetlands health.

"It's unlikely to me that the problem is really going to be that we won't have variability in lake levels," he said. "It will be that we still have too much."
Summer weather patterns appear to be more static than they used to be, most recently with Georgia and Tennessee on the brink of a border dispute over a reservoir this spring, and this summer suffering with too much rain for the peaches, peanuts, and pecans.

1 comment:

David Karlson said...

What is your famous line? "Complex adaptive systems do exactly as they please."