Turning Source to Sink: Can the Fens Help Combat Climate Change?
Turning Source to Sink: Can the Fens Help Combat Climate Change?
The Fenlands of eastern England are known as the breadbasket of Britain, producing around a third of the nation’s vegetables and employing roughly 80,000 people in the agricultural food chain.
Historically, the Fens were an extensive maze of wetlands and snaking rivers. Today, this landscape is maintained as productive and economically valuable farmland through an intensive programme of drainage and river management.
Only 1% of the original, ecologically rich wetlands remain. These now rare and vulnerable wetland habitats are precious in more ways than one. Healthy wetlands are one of the most effective carbon sinks on our planet, but drainage in fact turns them into carbon emitters—potentially making climate change worse.
The Carbon Challenge
Scientists estimate that drained wetlands (or peatlands) emit around 4% of all human greenhouse gas emissions globally—more than that produced by aviation.
“I think many people are unaware that drained peatlands are such a significant source of carbon dioxide, by removing that cap of water from the soil, we’ve essentially taken off a lid that had been holding carbon in.”
— Thomas Marquand, PhD student studying ways to mitigate carbon dioxide emissions from Fenland soils.
In waterlogged conditions, rich wetland vegetation doesn’t fully decay and instead piles up to form layers of peaty soil, locking in carbon that would otherwise be released. However, when wetlands are drained and oxygen gets into the dry soil, microbes consume the plant matter and give off carbon dioxide.
Exploring Solutions
Rewetting areas of peatland slows the release of carbon, and it may be possible that this would also return the land to a mode where it traps carbon, in turn providing a means to offset carbon emissions. But wholesale rewetting would bring negative social and economic impacts to agriculture, communities, and livelihoods throughout the Fens.
“We’re working on identifying a middle ground. A workable solution might involve partial rewetting, meaning less disruption to agriculture.”
Marquand has been running tests on Fenland soil in the lab. The science is simple—he adds water to the soil to simulate peatland rewetting at a small scale and measures gases released from the soil over several months.
Balancing Carbon and Methane
Besides measuring carbon dioxide, Marquand is also monitoring methane emitted from the soil. Previous studies have shown that when peatlands are rewetted, carbon emissions drop rapidly and stay low, but methane emissions rise. This is a potential setback because, even when released in small quantities, methane is a more potent greenhouse gas than carbon dioxide.
“In my research, I’m exploring whether there are ways we can get the benefits of trapping carbon without the penalty of increased methane emissions.”
For Marquand, an intriguing aspect of studying wetlands is getting to know the habits of the methane-eating organisms that thrive in these boggy, oxygen-poor environments.“Their almost alien metabolisms are unlike any animals, plants or fungi. Some might consider them the underdogs of the metabolic world, but they are a fascinating hold-over from Earth’s ancient, oxygen-poor environment and are in fact extremely specialised.”
Collaborative Efforts
Marquand presented his research at the AGU’s Annual Meeting 2024 in December. He is part of the Centre for Landscape Regeneration, funded by UKRI NERC and led by the University of Cambridge.
The Centre’s work in the Fens is conducted with expert partners who are working together to develop solutions to support the region, balancing various priorities: restoring and conserving natural systems, reducing carbon emissions, maintaining agricultural yields, and protecting local livelihoods.