Here in Michigan, we are aware of how lake levels have dropped. Levels of the Great Lakes have been lower than average for the last 12 years. Lakes Michigan and Huron are particularly low.
Can we attribute this to climate change/global warming? I have no idea. Federal recordkeepers note that water levels have dropped below average before — including in the mid 1960′s and during the entire 1930′s — often much lower than average compared to the last 12 years.
The lakes levels are getting some attention including multiple theories as to the reasons why including climate change, recent drought conditions, warmer water temperatures, increased evaporation, loss of ice cover, and changing precipitation patterns (all of which are really rooted in climate change). Some studies have concluded that the drops in Lakes Michigan and Huron are, in part, due to 1962 dredging in the St Clair River and subsequent erosion. Others disagree. While lake levels have fluctuated within regular ranges, one recent predicted permanent drops of up to two feet in lake levels.
While the cause is unclear, the effect is not. The drop in lake levels impacts pleasure boaters and commercial shipping. The drop in lake levels is unlikely to cause stops in commercial shipping as is feared for the Mississippi River (in fact less ice may mean a longer shipping season), but as lake levels drop, ships cannot carry as much — reportedly losing between 70 and 270 tons of cargo per inch of “draft” lost, depending on the size of the ship. Less cargo means, of course, higher costs and lower profitability. That does not include the costs to dredge harbors which likely will be in the millions of dollars.
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