As weather extremes become the norm, taxpayers must foot the bill for climate chaos: Don Pittis

The final tally of Great Lakes flood damage is still being calculated. But as U.S. President Donald Trump hints he will pull out of the Paris climate agreement, experts are warning that taxpayers must be prepared to eventually spend big in order to cope with a changing climate in the Great Lakes Basin.

As a major transportation corridor, reaching deep into the Canadian Prairies through rail links, managing the vast and complex water system remains a national and international priority.

"The irony is that most of these economic studies we've been doing of late have been because of the very low water levels and what that would do for transportation, recreation property, fishing and so on," says Gail Krantzberg, an engineering professor at McMaster University who has been studying the Lakes for 30 years.

From drought to flood

As Krantzberg has observed, the engineers charged with managingthe sprawlingGreat Lakes and St. Lawrence Seaway system now face what could bemuch more expensive problems: unpredictability and extremes of volatility.

As a dynamic living system, the rise and fall of water levels rechargewetlands and scourshorelines. In some years, one species benefits, creatinga new food source that suppliesfuture generations of another species downstream.

"Fluctuations are what we want," saysKrantzberg. "Extremes are where we get impacts."

Signs suggest those fluctuations are getting more extreme and extremes are expensive.

Trying to balance the many conflicting demands of an ecosystem and economic resourceshared between Canada and the United States is the unenviable task of the International Joint Commission, which monitors shared waters between the two countries.

"Certainly on the upper Great Lakes, the levels were low for a little over a decade," says David Fay, aCanadian engineer who advises the IJC.

He says levels on LakeHuron hit an all-time low in 2013, forcing ships on the St. Lawrence Seaway to reduce loads and cutting the amount of water available for generating electricity. Ferry services were interrupted, marinas were left high and dry, and recreational property usersfaced a long, mucky hike out fora splash in the lake.

The low water levels in the upper Lakes were blamed on climate effects: lowprecipitationand warm temperatures that led to poor ice cover and higher rates of evaporation.

Climate effects

But suddenly everything changed and now a different group of business owners and residents are complaining, as high water erodes banks and threatens property values.

"Water levels on the upper Great Lakes, Lake Superior, Michigan and Huron, as well as Erie, are all well above average now and Lake Ontario is now at its record high," says Fay.

Fine-tuning such a huge, dynamic natural system covering hundreds of thousands of square kilometres is not easy.

One way to think of the Great Lakes is as a series of bathtubs. If the water pouring in through the tap is larger than the amount pouring out, the level of the tub rises.

But the enormous extent of the Great Bathtubs requires some changes in thinking.

Raising the level of the dam between Lakes Superior and Huron might sound like a good idea when levels are high on the lower lakes, Fay says, but such a change would take years to work its way down to Lake Ontario.

By bathtub standards, the lakes are wide and shallow, so evaporation makes a real difference.

And rainfall which has been exceptionally high this year is not just the shower emptying into the tub, but all the precipitation over the entire watershed, including the snow that accumulates and pours into the lakes during thespring melt.

Pull the plug

While property owners and municipalities would like to simply open the plug a little wider and let the water drain, that strategy has beencomplicated by other events, Fay says, including erratic freezing in the St. Lawrence River this past winter.

Letting out too much water before the river is properly frozen leads to the creation ofice dams, as unstable ice is swept into the river's narrow points.

When spring finally came, outflows from Lake Ontariohad to be held back to compensate for flood-level spring runoff from the OttawaRiver system.

Then came two months of rain.

"Right now, the flow in the [St. Lawrence] river is atits maximum for safe navigation," says Fay.

Yet if Lake Ontario rises further, that flow may have toincrease, leading to more damage downstream and a costlyinterruptionin shipping traffic.

The accumulated damage of this year's flooding has been estimated at between hundreds of millions and billions of dollars, but according towater engineer Tirupati Bolisetti, at the University of Windsor, the biggest expense will be rebuilding public infrastructure to cope withincreasingly volatile conditions caused by climate change.

100-year events every 25 years

Bolisetti's own research shows that while the number of rainy days is declining, "any given rainfall is significantly higher thanwe used to have in the past."

"When you have to design the stormwater or flood-control structures, what used to be 25-year storm events have become five-year storm events now," he says. "What used to be 100-year storm events have become 25-year storm events."

So what kind of spending will be required in the Great Lakes Basin?

"If I hadto project the costs for the reconstruction and upgrading of the infrastructure for climate change preparedness, it will be easily a few hundreds of billions," says Bolisetti.

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