As spring and summers get warmer and drier, the UK wildfire season is getting longer, according to a study published in the journal Environmental Research Letters. The authors warn that more fires occurring over more months of the year are causing more carbon to be released as CO2.
If the fires occur specifically on peatlands — rich in carbon — it can almost double the carbon emissions caused by fires. Despite being only a quarter of the total UK land area burning each year, peatlands caused up to 90% of the annual carbon emission since 2001. A further problem is that — unlike heather moorland, which takes up to twenty years to regrow after a fire — burnt peatland take centuries to reaccumulate. The loss of this carbon store makes the increasing wildfire frequency on peatlands a real cause for concern.
Peat only burns when it’s hot and dry, which is more likely to occur more often with climate change. The peatlands of Saddleworth Moor in the Peak District, and Flow Country in northern Scotland, in particular, have been affected by considerable wildfires in recent years. According to the researchers, land managers are crucial in helping achieve Net Zero climate goals by keeping peatlands wet. The aim is to reduce the likelihood of intense fires and high carbon emissions.
“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,” said Dr. Adam Pellegrini in the University of Cambridge’s Department of Plant Sciences, senior author of the study. “Peatland reaccumulates lost carbon so slowly as it recovers after a wildfire that this process is limited for climate change mitigation. We need to focus on preventing that peat from burning in the first place by re-wetting peatlands.”
For this study, the researchers included all UK wildfires over 20 years and assessed their location and the amount of carbon they released. The calculations considered the type of vegetation and carbon content, soil moisture, and peat depth. Using UK Met Office data, the team also used simulated climate conditions to predict how wildfires in the UK may change in the future.
Results show that the UK’s fire season has lengthened dramatically since 2011, from up to four months in 2011-2016 to nine months in 2017-2021. This increase is particularly marked in Scotland, where almost half of all UK fires occur. The researchers also estimated that around 800,000 tonnes of carbon were released from fires on UK peatlands between 2001 and 2021. The 2018 Saddleworth Moor fire emitted 24,000 tonnes of carbon, and the 2019 Flow Country fire emitted 96,000 tonnes of carbon from burning peat.
The authors suggest that rewetting the peat is the best way to protect it. However, this will require land managers to be incentivised. This won’t be easy, but the impact could be significant. “Buffering the UK’s peatlands against really hot, dry summers is a great way to reduce carbon emissions as part of our goal to reach net zero. Humans are capable of incredible things when we’re incentivised to do them,” concluded Pellegrini.
Baker, Perry M, Betts R, Schoenecker J and Pellegrini. Spikes in UK wildfire emissions driven by peatland fires in dry years. Environ. Res. Lett. 20 034028DOI 10.1088/1748-9326/adafc6