Preserving the world's peatlands – and the vast carbon stores they contain – is vital to limiting climate change, researchers say.
The study, led by the University of Exeter and Texas A&M University, in collaboration with the University of Nottingham, examines peatland losses over the course of human history and predicts these will be "amplified" in the future.
Peatlands are expected to shift from an overall "sink" (absorbing carbon) to a source this century, primarily due to human impacts across the tropics, and the study warns more than 100 billion tons of carbon could be released by 2100, although uncertainties remain large.
Peatlands are currently excluded from the main Earth System Models used for climate change projections – something the researchers say must be urgently addressed.
"Peatlands contain more carbon than all the world's forests and, like many forests, their future is uncertain," said Professor Angela Gallego-Sala, of Exeter's Global Systems Institute.
"Peatlands are vulnerable to climate change impacts such as increased risk of wildfires and droughts, the thawing of permafrost and rising sea levels.
"However, the main threats to peatlands are more direct – particularly destruction by humans to create agricultural land.
"So the future of peatlands is very much in our hands."
Peatlands are a type of wetland found in almost every country on Earth, currently covering 3% of the global land surface.
Professor Gallego-Sala says they have been "overlooked" in some climate models because they are seen as "inert" – neither absorbing nor emitting carbon at a rapid rate when left alone.
This exclusion from models makes it hard to estimate future changes, so the study combined existing research with survey estimates from 44 leading peatland experts, including Professor David Large, Head of Chemical and Environmental Engineering and Professor Sofie Sjogersten, from the School of Biosciences at the University of Nottingham.
Based on this, it estimates total carbon loss from 2020-2100 at 104 billion tons.
Previous research by Professor David Large, from the Department of Chemical and Environmental Engineering at the University of Nottingham informed the Exeter study. With expertise of how peatland behaves over days to millions of years, Professor Large was also an author on the paper.
"Peatlands are a major and potentially vulnerable global carbon store. Under future climate change what will happen to this vast carbon store is uncertain. Peatlands need to be included in future climate models and more work is required."
Professor Sjogerston said: "Preserving the world's peatlands, including the ones discovered more recently in the Amazon and Congo is vital to limit climate change, and we can collectively reduce peatland destruction and conversion by implementing sustainable practices and effective policies as soon as possible."
The authors stress this estimate is highly uncertain (losses up to 360 billion tons to gains of 103 billion tons) – but it demonstrates the need both for inclusion in models and better peatland preservation.
