Sunday, July 19, 2009

Surprise, Even with Al Gore's Prognostications, Great Lake Levels are Up

Ah, Summer, when a man's thought turns to diving (ok when a certified scuba diver's thoughts turn to diving but anyway).

Who could possibly have guessed that the Great Lakes are continuing a cycle and are now at or beyond their average levels.

The Detroit News: Great Lakes water levels rebound after long slump
Great Lakes water levels are rebounding after a decade-long slump that hammered the maritime industry and even fed conspiracy theories about plots to drain the inland seas that make up nearly one-fifth of the world's fresh surface water.

The three biggest lakes -- Superior, Huron and Michigan -- have risen steadily since fall 2007, when for a couple of months Superior's levels were the lowest on record and the others nearly so. Erie, shallowest of the lakes, actually exceeded its long-term average in June. So did Lake Ontario, although its level is determined more by artificial structures than nature.

Apparently these lake level changes are normal:
he lakes follow cycles, rising and falling over time. Scientists say it's a natural process with environmental benefits, such as replenishing coastal wetlands. But extreme ups or downs can wreak havoc for people.

During the mid-1980s, levels got so high that houses, businesses and even sections of roads were swept away along Lake Michigan's southeastern shoreline.

Then a sudden, deep drop-off began in the late 1990s.
And now the lake levels are heading back up again.

Of course we have to maintain the specter of global warming as the culprit:
Scientists attribute the rebound primarily to wetter, colder weather the past couple of years. But if grim computer modeling proves accurate, global warming will cause the lakes to recede up to 3 feet this century.

Mind you, these lake changes have been cyclical and been going on for centuries:
Records extending to the mid-1800s document a series of larger rises and dips at roughly 30-year intervals, said Craig Stow, a scientist with the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory in Ann Arbor.

In short the lakes rise and fall on natural cycles and we may now be headed back on an upswing, no need to panic. Since I'm scheduled to go on a couple dive charters in August the lake levels shouldn't pose much of a problem except for making the wrecks a little deeper than they were last year -- we'll see if the depth gauge registers a change or not.

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