What On Earth

Canada's swamps are the secret weapon to fighting climate change, say experts

Boggy marshes and wetlands across the country are the secret stars of carbon capture, but most people don’t understand their worth, said Christina Davy, a research scientist for the Ontario Ministry of Natural Resources and Forestry.

Bogs, marshes and wetlands across the country are excellent carbon sinks

Research scientist Christina Davy, seen here with a snapping turtle, says most people don't realize the importance of bogs, marshes and wetlands when it comes to carbon capture. (Kevin Chan)

They may be among the most misunderstood landscapes, but scientists say Canada's swamps have a powerful role to play in combating climate change.

Bogs, marshes and wetlands across the country are the secret stars of carbon capture, but most people don't realize their worth, said Christina Davy, a research scientist for the Ontario Ministry of Natural Resources and Forestry.

"Because they do look like big mud puddles when you don't understand how important they are, I think we don't always give them the value that they really deserve," she told What on Earth host Laura Lynch. "And I think that people understanding why they're important is a big step to conserving them and slowing the rate of loss."

Davy, who runs a conservation ecology lab at Trent University in Peterborough, Ont., is among a number of scientists singing the praises of Canada's carbon-capturing swamps, sounding the alarm about saving what's left of them and restoring them where possible.

Davy collecting a water sample in a wetland. (Anne McCarthy)

Urban encroachment and agriculture have replaced about three-quarters of wetlands in heavily populated southern Ontario, she said, but there's significant wetland loss all across Canada's south.

Gail Chmura, a professor in the department of geography at McGill University, studies the salt marshes around the Bay of Fundy, between Nova Scotia and New Brunswick. She describes these wetlands as "grassy meadows that are flooded by the ocean tides twice a day."

They're mostly comprised of grasses with a few wildflowers in the mix. "And that's what makes them such a good carbon sink, because they have tremendous root systems that store the carbon dioxide that the plants take out of the air," she told Lynch.

Geographer Gail Chmura studies the salt marshes around the Bay of Fundy, between Nova Scotia and New Brunswick. (Submitted by Gail Chmura)

Like all plants, they undergo photosynthesis, during which they take carbon dioxide out of the atmosphere and store it in the green part of the plant.

"But, also, three to five times more gets stored in the organic matter — in the roots in the soil. And those roots stay there in this kind of ecosystem. They don't decompose very much because the soil is so wet and they just keep accumulating more and more soil as sea level rises."

Since that's been happening for millennia, "we have 3,000 years of carbon stored in these marshes," said Chmura.

From testing soil at the site, she and her colleagues have calculated that the marshes hold an amount of carbon equivalent to driving a vehicle for 225 billion kilometres.

While 77 per cent of the area's marshes have been lost to diking and draining, Chmura said, restoring them is actually relatively simple. "If we open up those dikes, tidal water starts to come in and very quickly deposits all that Bay of Fundy mud."

Dipper Harbour salt marsh, located on the Bay of Fundy. (Submitted by Gail Chmura)

At one restoration site in Aulac, N.B., they found that carbon capture was "way above anything we expected" after just six years, she said.

"They immediately serve as tremendous carbon sinks — as good a carbon sink as the undisturbed marshes in the same region."

On the opposite coast, where Mervyn Child's Indigenous ancestors relied on the wetlands of Kwakiutl First Nation for food and medicine, there's another effort underway to restore and protect the area's rich saltwater marshes.

That's not only good for carbon capture, but for the local watershed and the wildlife within.

"There's so much waterfowl, of course, in there. There's lots of migratory birds and there's salmon — chums, pinks and Coho in there — and a variety of trout," he said. 

In March, the community won a B.C. government grant to help reverse the effects of logging and erosion there. 

Rising sea level and the growing intensity of storm surges there threaten the balance of freshwater and saltwater, said Child. Plus, nearby logging has filled a local river with so much debris that it has rerouted elsewhere through the forest, disturbing salmon habitat and making a treasured local swimming hole from his youth disappear altogether.

Putting a value on wetlands

Part of creating the will to protect wetlands is assigning a price tag to them, said Sheri Young, climate change and energy specialist with the town of Okotoks in southern Alberta.

"We decided to count up all of the natural assets … that provide services to the town of Okotoks — air quality and carbon sequestration and stuff like that. And we counted those up and put a value on them so that we could tell people how much those are worth to us as a town," Young told Lynch.

That number came out to $3.2 million. 

Now when developers come knocking, or when it's time to figure out where to put a bike path, everyone has "a general idea of how much they are worth." 

[Alberta] has lots of great natural assets and we want to preserve those and put our roots deep into the soil … to preserve it.- Sheri Young, climate change and energy specialist

With a limited supply of water and a climate that has warmed at more than twice the global average in the last 100 years, Okotoks has good reason to preserve its wetlands, which help counter the warming "urban heat-island effect" of all those houses and roads, said Young.

She said that it's crucial to restore wetlands for their own sake, but also to counteract the 404,000 tonnes of carbon the town emits every year and adapt to increasing storm and heat events there.

"I live here. I have children here. I have roots here. And … there isn't anywhere better. Canada is a lovely place. Alberta is a wonderful place. It has lots of great natural assets and we want to preserve those and put our roots deep into the soil … to preserve it."


Written by Brandie Weikle. Produced by Molly Segal, Jennifer Van Evra and Serena Renner.

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