Fire emissions from peatlands in the United Kingdom have released an estimated 800,000 tonnes of carbon between 2001 and 2021, a new study has warned. If global temperatures rise by 2 degrees Celsius, emissions from peatland fires could increase by at least 60 per cent compared to current levels, reaching an annual average of approximately 3.8 million tonnes of carbon, researchers have found.
Published in the journal Environmental Research Letters, the study highlighted the significant environmental impact of peatland fires, equating the projected emissions increase to those produced annually by around 133 commercial aircraft, 820,800 passenger vehicles, or 414,000 homes.
Peatlands, a type of wetland, cover at least 3 per cent of the global land surface and account for 9 per cent of the UK’s land area. When in a healthy condition, they sequester more than three million tonnes of carbon dioxide from the atmosphere each year. However, these ecosystems are increasingly vulnerable to fire due to climate change and land management practices.
“The widespread nature of northern peatlands, combined with the increasing threat of these ecosystems burning, means that these sites are increasingly vulnerable to producing high emissions,” the researchers wrote in the study.
Fire severity in non-peatland ecosystems, such as forests, is determined by the type of vegetation and fuel load also plays an important role. This makes it fairly simple to forecast aboveground carbon emissions.
Peatland fires, on the other hand, are driven by the combustion of soil organic carbon. The depth of burning can range from 1-5 kilogrammes of carbon per square centimetre (kg/cm²) in pristine peatlands to as much as 25 kg/cm² in drained peatlands. Moisture levels, influenced by climate, topography and land management, play a key role in determining fire severity.
Despite their significance, northern peatlands remain less studied than their tropical counterparts. To fill this gap, researchers analysed UK peatland fire-driven carbon losses from 2001 to 2022 using high-resolution data on peatland extent (defined as peats deeper than 0.5 metres), vegetation type, agricultural land cover, soil moisture and fire occurrence. They found a strong correlation between peatland fires and periods of dry climate conditions.
Their analysis showed that peatland fires have accounted for up to 90 per cent of the UK’s annual fire-driven carbon emissions since 2001, with spikes occurring in particularly dry years. The study also found that the UK’s fire season has lengthened dramatically since 2011. Between 2011 and 2016, the season lasted between one and four months, but between 2017 and 2021, it extended to between six and nine months.
“We found that peatland fires are responsible for a disproportionately large amount of the carbon emissions caused by UK wildfires, which we project will increase even more with climate change,” Adam Pellegrini in the University of Cambridge’s Department of Plant Sciences, senior author of the study, said in a statement.
Pellegrini emphasised the need to prevent peat from burning in the first place, advocating for rewetting as a key solution. Rewetting refers to any deliberate actions taken to restore a drained peatland's water table to its original level.