Raphael Thys
Swamps are key to fightling climate change — Photo by Carlo Lisa on Unsplash
Our climate crimes are catching up to us. If we don’t do something dramatic soon, the world will be plunged into a self-made apocalypse, complete with famine, plagues, disease, and ecological collapse. To stop this horrific prediction from coming true, we not only have to halt our planet-killing ways but also repair the damage we have caused over the course of the past few decades. One way to do this is carbon capture, but unfortunately, our technology lags far behind where it needs to be in order to make that a viable option. However, scientists have recently found a fantastically simple way to store over a trillion tonnes of carbon dioxide. But how? And is this the silver bullet we need to save planet Earth from ourselves?
These scientists looked at blue carbon. This is the carbon that is stored away in water-based environments. To be precise, they looked at a particular type of blue carbon usually found in wetlands (including habitats like swamps, peat bogs, and marshes). You see, these environments are incredibly good at removing carbon from the atmosphere and stashing it away safely. For example, peat bogs only take up about 3% of the world’s land area, yet they store twice as much carbon as the world’s forests.
This storage happens because the shallow water or water-logged soil is anoxic, meaning it has no dissolved water in it. As a result, the plants growing in this environment build their bodies using carbon from the air (like all plants do), but when they die, they aren’t broken down by oxygen-breathing bacteria like normal. This means that rather than the carbon they captured in their bodies being re-emitted into the atmosphere, it is buried with them. This is why the soil and mud in wetlands are so carbon-rich.
But these environments are under threat. A combination of ecological changes and human impact is causing them to dry up and degrade, and when they do, they emit their stored carbon.
A recent study found that half the world’s wetlands are degrading due to low water levels. If nothing is done to stop this, they predict these degraded wetlands will emit 408 billion tonnes of carbon dioxide by 2100. While this doesn’t necessarily constitute direct emissions from human activity, it is caused by humanity’s environmental negligence and should be counted towards our total carbon footprint.
Luckily, this study also looked at what would happen if we revived these wetlands. They calculated what would happen if we took 4 million square kilometres of these degrading wetlands and rewetted them so that the water table was at ground level. In theory, doing so would halt the amount of carbon dioxide leaking from them. Unfortunately, it would also dramatically increase their methane emissions, which is a 25 times more potent greenhouse gas than carbon dioxide.
But their results showed that this would reduce the carbon dioxide emitted by these environments by 2100 by at least 100 billion tonnes and at most 400 billion tonnes. Moreover, the extra carbon stored in these wetlands would cancel out the greenhouse effect of the increased methane emissions.
But this study only looked at reviving the degraded wetlands. What if we nurtured the other half that are currently healthy?
Well, another recent study looked at exactly this. Again, this all revolved around the wetlands’ ability to make and build extremely carbon-rich soils and the fact that conservation can help keep this process consistent. This might be as simple as ensuring water supply by not damming rivers; keeping the water supply clean; or supporting keystone species in these habitats.
Now, this may sound simple, but the results will be dramatic as up to 650 billion tonnes of carbon dioxide could be removed from the atmosphere and stored away in these healthy wetlands by 2100. That is a best-case scenario, but even the worst case is still fantastic, with 150 billion tonnes of carbon dioxide removed.
So, by both restoring (first study) and conserving (second study) wetland areas, we could remove up to 1.05 trillion tonnes of carbon dioxide by 2100 (or at the very least 250 billion). Surely this massive amount of carbon storage is enough to reverse climate change?
Well, we are currently emitting around 35 billion tonnes of carbon dioxide each year, and that figure has been growing. This means that, even in the best-case scenario, these wetlands will only offset an equivalent of 30 years of current emissions, and in the worst case scenario, will only offset around 7 years of current emissions.
So no, wetlands aren’t a climate change silver bullet. But we now know how to make a severe dent in the climate emergency without the need for complex carbon capture technology. Armed with information like this, we can lobby governments to not only conserve these precious habitats but also revive them. Hopefully the few extra decades these wetlands will provide us will give us enough time to change our ways, perfect net-zero technologies, and become the sustainable society we need to be.