Scientists warn that climate change is bringing freshwater streams rushing through Canadian wetlands

On the July 5 installment of a popular radio series called Resilience, scientists from across Canada’s oil sands belt came together in Alberta for a two-day summit called Reconnecting Climate Risk. Canada’s harsh climate is getting all the attention these days. It’s here that the country’s most carbon-intensive industry is allowing the bulk of the climate pollution that the world depends on from burning fossil fuels. But the region, much of which is prone to wildfire and river flooding, is also home to an interesting hidden climate threat: what’s known as deluge water flooding.

When you use the term “idealized wetland,” you may think you’re describing what’s on our prairies here in the U.S. The sort of thing that we see in Mississippi, Arkansas, or North Carolina, but what scientists are calling “delta wetland” elsewhere on Earth. Delta wetland is low-lying, freshwater areas formed by subsurface pressure in tropical water basins. They’re often 100 miles or more wide and, due to high salinity in the water, 100 feet or more deep.

Canadian researchers describe a different type of delta wetland. Normally, the wetland is dry, like a mine, or wet, like a floodplain. But since glaciers melted on the land between roughly 15,000 and 10,000 years ago, there were also cold-water streams flowing through the wetland, running into freshwater caves below. Now, as time marches on, the delta wetlands are flowing back downhill.

The problem isn’t just that streams are returning to their former home. The threat, as scientists like their colleagues in the Canadian Cetacean Consortium call it, is what they’re doing to the wetlands as they return. If you look at the ribbon-like bends in the water in delta wetlands, you can see water moving at a couple hundred times the rate it used to. In these areas, you have much higher elevation rates (a few centimeters a day, not a few inches a day like other areas of the world), and dry ecosystems are transitioning into intense wetland areas. It’s roughly the same phenomena as what we see on island-strewn islands in the Amazon rainforest, such as the Panamanian Isla El Castillo.

It’s “the most immediate and serious priority,” said Amanda Bowal, a professor at the University of Alberta, who’s one of the primary researchers studying the phenomenon. And, as Bowal points out, research focused on it could have a big impact. “As these wetlands arise, it will determine how much greenhouse gas emissions get emitted,” she told me at the conference.

Right now, there’s no set rule about how large a delta wetland can be. Across the U.S., it’s been a major focus for marine scientists because of its role in providing habitat for lobsters, sea turtles, and big plankton. But in Canada, scientists are putting more focus on the difference. “You don’t see much of this, particularly because of Canada’s progressive approach in terms of managing our freshwater,” said Frederic LaRose, a senior scientist at the Institute for Canadian Environment and Sustainable Development at the University of Alberta.

This is an issue that affects both the future of the land and the future of the wildlife. For example, the number of fish species that could be affected — such as juvenile stocks of salmon and trout — could be in the dozens or even hundreds. Humans have only gotten a partial picture of the impacts of their massive delta wetlands up to now. And, as Bowal and others note, it’s affecting animals that, to be clear, are connected with humans on a broad scale.

And those creatures are going to pay a high price, at least in the short term. Some scientists say to expect tiny fish and creatures that use river sediments as shelter. However, if those habitats become deluged, it could have a major impact on the wildlife that have lived there and should have roots in the ecosystem. That’s why the researchers are sounding the alarm — and hoping for real change in policy.

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