Quantifying carbon capture in Canadian wetlands

Wetlands are one of the world’s most carbon-dense terrestrial ecosystems, drawing planet-warming carbon dioxide from the atmosphere and storing it for centuries or even millennia. That makes Canada’s abundant peatlands, swamps and marshes powerful tools in the fight against climate change. 

But exactly how much carbon do these ecosystems capture? And how does that change when they’re drained or disturbed — whether it’s for agriculture, housing developments, oil sand operations or mining in Ontario’s peatland-packed Ring of Fire? 

Those are important questions for Kelly Bona, a research scientist at Environment and Climate Change Canada who models the contributions of wetlands for Canada’s national greenhouse gas inventory. 

According to the federal 2030 Emissions Reduction Plan, nature-based climate solutions have significant potential to contribute to Canada’s decarbonization goals — and provide many other benefits. However, Canadian wetland data is scarce, says Bona: “We know they store a lot of carbon, and we know when we disturb them that they emit a lot of carbon, but we don’t actually have good values.” 

The equations are also complicated. Plants take up carbon through photosynthesis during the day and store it in their biomass. But they also release some of it through respiration. They sequester more carbon in the summer, when plants are active, and less in winter. And wetlands contain anaerobic microbes that generate methane — a potent greenhouse gas — when they break down organic material, offsetting some of the carbon storage benefits.

How do researchers track the complexities of wetland carbon dynamics?

McGill University scientist Sara Knox is helping fill in the blanks and understand those complexities through the CARBONIQUE study: the largest and most comprehensive assessment of wetland carbon dynamics in Canada. Her team at the EcoFlux Lab and her CARBONIQUE colleagues have installed permanent monitoring towers in natural and disturbed wetlands across southern Quebec to track carbon dioxide, methane, water and energy exchanges between the land and atmosphere. 

“We can actually quantify fluxes, that direct measurement of carbon in and out of our ecosystems,” explains Knox.

While the towers provide valuable long-term data, they are expensive, time-consuming to install and fixed in place. So Knox’s team is also deploying new portable monitoring stations funded by the CFI to gather data from a range of sites and to monitor the impacts of droughts or flooding as they happen. 

“This infrastructure allows us to leverage what we already have and answer new questions we couldn’t have addressed otherwise,” says Knox. 

This summer, for example, the team installed a portable station in a drained, agricultural peatland and will compare its measurements with those from a natural, undrained peatland nearby to see how draining changes a bog’s carbon balance.