Warming likely to affect Great Lakes shipping

Global warming could devastate the Great Lakes region's shipping industry by lowering water levels, as predicted under the current regime of climate-change scenarios.

"I don't think there has been much thought put into it by anybody," said Scott Thieme, chief of the U.S. Corps of Engineers' Great Lakes hydraulics and hydrology office.

Lake levels have risen and fallen in 30-year cycles since at least 1860, records show, but a study last fall issued by 75 area scientists from nearly 50 government, business, academic, and public-interest groups claimed warming and evaporation trends could cause Lake Erie water levels to drop 3.28 feet to 6.56 feet by 2066.

The estimates were based on findings by the Intergovernmental Panel on Climate Change, the world's most prestigious group of climatologists.

A subsequent paper that appeared in Environmental Science & Technology suggested Lake Erie and Lake Ontario water levels will become largely dependent on the rainfall they pick up from additional hurricanes and tropical storms. More violent weather is anticipated as the climate warms. Lakes Superior, Michigan, and Huron are too far north to pick up substantial amounts of rain from storms, the report stated.

Every inch lake levels fall affects the shipping industry and its economy by millions of dollars a year.

Thieme said he's aware of forecasts for water-level declines and is perplexed why the government hasn't taken the issue more seriously, given what's at stake.

A big enough drop in water could even affect the future of the U.S.-Canada tunnel between Detroit and Windsor, he said.

The Corps of Engineers spends $20 million a year to dredge 4 million cubic yards of sediment from all Great Lakes harbors and channels, the equivalent of 400,000 truckloads of soil.

At some rivers, only so much more dredging can occur before hitting bedrock. The Detroit River bottom was blasted in the 1920s and 1930s for a shipping channel. Blasting it deeper today would be a multibillion-dollar project.

There are several harbors with pipelines beneath their shipping channels. The lines carry chemical products, natural gas, as well as electrical, phone, and fiber optic cables. The cost of relocating those would be astronomical.

Even if relocating pipelines and blasting deeper through the Detroit River bedrock became viable, there "would be an awful lot of concern and resistance for environmental issues that there weren't years ago," Thieme said.

The Great Lakes region accounts for 70 percent of the nation's steelmaking capacity, 70 percent of its automobile production, and 55 percent of all heavy manufacturing. But it hasn't been moving cargo for such manufacturing as efficiently as it could.

Three of every four vessels leave their docks "light loaded" because of the lack of channel depth, according to testimony delivered to the House subcommittee on Energy and Water Development last year by James Weakley, president of the Lake Carriers' Association.

The 63 U.S.-flagged vessels represented by the association leave behind more than 8,000 tons of cargo per trip for every inch of lost channel depth.

Eight thousand tons of iron ore is enough to build 6,000 vehicles. Eight thousand tons of coal is enough to produce three hours of electricity for the Detroit metro area. And in the housing industry, 8,000 tons of limestone is enough to build 24 homes, according to Weakley's testimony.

(E-mail Tom Henry at thenry(at) theblade.com)

(Distributed by Scripps Howard News Service, www.scrippsnews.com.)