Authored by Kim Kleinke, Marissa Davies and Maria Strack (Wetland Soils and Greenhouse Gas Exchange Lab) on November 9, 2022
In the face of the climate emergency, you’ve probably heard “save our rainforests” or “plant two billion trees”. We’re producing too much carbon dioxide (CO2) and causing climate change. Trees uptake CO2 and cutting them down releases it back to the atmosphere, so it seems like a no-brainer to protect and plant trees. But what other important ecosystems do we have? Maybe you know that the ocean absorbs a lot of CO2 (about 30% of what we release into the atmosphere). What you may not know about is the importance of wetlands. Like forests storing carbon in trees, wetlands hold carbon underground in soil, and in northern regions, they currently store over 30% of the soil carbon while only covering around 3% of the total land area!
Wetlands being wet means that decomposition is slow (think of how well “bog bodies” are preserved). Slowly decomposing plant litter and other organic materials hold onto their carbon and do not release much CO2 into the atmosphere. The CO2 that is slowly released is outbalanced by the living plants, including trees, actively sucking up CO2. With this imbalance, carbon is consistently stored in the decaying organic matter leading to carbon rich soil, often called peat. So, wetlands act like a bank account for carbon that is stored beneath our feet. But, this storage takes time, building up slowly over thousands of years.
Canadian wetlands cover about 13% of our land area and account for almost a quarter of global wetlands. Unfortunately, wetlands and their importance often fly under the radar when it comes to land use planning and are not given the protection they deserve. Across Southern Ontario, we have lost about 56% of our wetlands to human development - in some places as much as 90%! Just like cutting down the rainforest, draining or building over wetlands causes us to lose both the active uptake of carbon and a large amount of the stored carbon. Once wetlands are no longer wet, the organic matter in the soil starts to decompose more quickly and carbon is released. Our development in Southern Ontario has released wetland carbon stocks leading to a reduction in the carbon stored of 2 billion tonnes since the 1800s. This loss is equivalent to the average annual greenhouse gas emissions of over a billion gasoline cars!
While wetlands can be restored or even constructed, the long-term carbon stocks are not quickly recovered. The process of carbon storage in wetlands is slow and restored wetlands may not recover their natural ability to store carbon for many years or decades. Wetlands are significant carbon stocks and have a high potential to mitigate climate change if properly protected and managed. Avoiding wetland disturbance provides more climate benefit than restoring areas that have been disturbed.
With our large wetland area and their importance for climate action, we as Canadians have a responsibility to protect these forgotten ecosystems. Take the time to learn more about wetlands and what you can do to help.