The Fenlands of eastern England are known as the breadbasket of Britain, producing around a third of the nations’ 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.
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,” said PhD student Thomas Marquand, who is studying ways to mitigate the carbon dioxide emissions released from the Cambridgeshire Fenland soils. “By removing that cap of water from the soil, we’ve essentially taken off a lid that had been holding carbon in.”
In waterlogged conditions, rich wetland vegetation doesn’t fully decay and instead piles up to form layers of peaty soil; locking in carbon which 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.
Wicken Fen in Cambridgeshire is home to areas of restored wetland. Credit: Glynis Peirson
Rewetting areas of peatland slows the release of carbon, and could potentially 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. Instead, said Marquand, “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 over several months.
Tom at one of his field sites in the Fens.
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,” said Marquand.
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.”
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.
Feature image: a typical Fenland view looking out onto farmland, credit: Glynis Peirson