Great Lakes Record Lows

  • Lower water levels on the Great Lakes make some channels such as the Muskegon River too shallow for big freighters to enter fully loaded. (Photo by Lester Graham)

The Great Lakes are hitting new record low water levels. The water is so low that
big 1000-foot cargo ships are running aground. There’s debate about
whether this is just part of the historic ups and downs of the Great Lakes, or if it’s the
effects of global warming. Lester Graham reports from Lake Michigan’s Muskegon
River, a trouble spot for some of the big ships:

Transcript

The Great Lakes are hitting new record low water levels. The water is so low that
big 1000-foot cargo ships are running aground. There’s debate about
whether this is just part of the historic ups and downs of the Great Lakes, or if it’s the
effects of global warming. Lester Graham reports from Lake Michigan’s Muskegon
River, a trouble spot for some of the big ships:


Here at the end of the pier next to the lighthouse, it’s cold, it’s icy and it’s windy. And
it’s hard to imagine a ship navigating its way into this channel, but ships do on a
regular basis to bring coal to a power plant. This year, however, some of the ships
have ended up aground here simply because of lower lake levels and more sediment
in the channel:


“There’s been three this summer here in Muskegon. They go hard up on the sand.”


Dennis Donahue is the marine superintendent for the National Oceanic and
Atmospheric Administration’s Lake Michigan field station at Muskegon, Michigan. He
says this year’s groundings of cargo ships just hasn’t happened that often in the
past:


“Well, we haven’t had a grounding here, certainly in the last 15 years due to water
levels.”


Lester Graham: “So what’s happening here? What’s going on?”


Donahue: “Well, there’s a couple of things, we’ve got the water levels dropping and
then we’ve got some weather patterns that are carrying sediment to the mouth of the
Muskegon River. So, those two compound and create shoal areas.”


So lower water and a rising bottom mean channels are more shallow. That means
ships have to carry less cargo, and that costs the shippers reportedly a million
dollars per ship per year.


Scientists have been monitoring the dropping lake levels for close to a decade now.
At NOAA’s Great Lakes Environmental Research Lab, Deputy Director Cynthia
Sellinger says she’s been seeing a trend in the weather that’s causing the problem:


“We’re having a lot less precipitation and a lot more evaporation. And that’s
impacting the water levels on the lake.”


Less snow pack and rain mean less water filling the lakes, and with warmer winters
Sellinger says there’s less ice cover to protect the lakes from massive evaporation.
Historically, about 50% of the lakes’ surfaces have been covered by ice. These
days, it’s more like ten to 20%. Cold air hits the warmer water and
carries it away. For Lake Superior alone, a one-inch drop is more than 500 billion
gallons. During the past decade, Superior has lost nearly 13 trillion gallons.


“The upper lakes, Superior, Michigan and Huron, are very close to their record low.
So, it’s approaching an extreme. Superior reached its record low in 1926 and just
this year it broke the record low for September. So, 2007 now is a new record low
for Lake Superior. Lakes Michigan and Huron are approaching their record low.”


Sellinger and her colleagues are not ready to say global warming is causing the
lower lake levels. It might just be a part of a long cycle of ups and downs of the lakes.
But the lower water levels do fit some of the computer model predictions about
global warming.


Lower lake levels causing problems for big cargo ships and marinas catering to
recreational boaters are problems enough. But, some environmentalists say if lower
water levels are caused by global warming, the pressures on the water in the Great
Lakes likely are going to get a lot worse. Andy Buchsbaum heads up the National
Wildlife Federation’s Great Lakes office:


“The hidden threat of global warming is that not only does it affect Great Lakes water
levels simply because of increased evaporation or increased temperatures changes
precipitation, but the threat it makes to Great Lakes water levels is even greater.
Because global warming, global climate change, is having massive effects already
and is likely to have even greater effects on water supplies in the Southwest, the
Southeast and all over the country. And as those pressures increase, the pressure
to divert Great Lakes water will increase exponentially.”


We don’t know whether new diversions to dry areas of the country could cause as
much of a problem as less precipitation and more evaporation of the Great Lakes
already do. But, it would certainly aggravate the problem. The effects of water
levels dropping further mean more economic hardship for shipping and tourism. And
environmentalists say ecological damage to coastal habitat that fish and other
wildlife need to survive could be on a scale that’s not been seen on the Great Lakes
in recorded history.


For The Environment Report, I’m Lester Graham.

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