Study finds UK’s first megafire unleashed nearly a year of fire emissions in four days

New analysis of carbon emissions from the 2025 Dava Moor Fire in Scotland could mark a shift in the risk of big, destructive, carbon-intensive wildfires in northern peatlands, according to a May 20 study in Nature Geoscience. 

The megafire’s exceptional size and intensity, the authors say, were made possible by climate conditions hot and dry enough that normally soggy soils can burn, releasing carbon trapped over millennia. 

Over just four days, the Dava Moor Fire torched as much acreage as usually burns in an entire year in the UK. It charred roughly twice the area as the nation’s next-largest fire in the past 20 years and released carbon equivalent to 85% of the average annual emissions from fires across the UK from 2001 to 2021.

The researchers found that while an accumulation of flammable vegetation above ground contributed to the fire’s rapid spread, extremely dry conditions primed the system to burn. Nearly 85% of the fire’s total emissions came from combustion of peat, a carbon-dense soil. 

“Through our sampling of scorched soils, we were able to document firsthand the extent of the peat loss over much of the burn scar,” said lead study author Johanna Schoenecker, a postdoctoral researcher in the lab of Adam Pellegrini, an assistant professor of Earth system science in the Stanford Doerr School of Sustainability. 

The fact that emissions from peat far outweigh those from surface vegetation in this fire matters because it could take centuries for new peat to form and sequester the amount of carbon released to the atmosphere, Schoenecker added, “making these losses effectively irreversible on any timescale relevant to climate action.”

“This study demonstrates why there needs to be more attention paid to preserving peatlands and addressing wildfires in areas where peatlands have served as long-term carbon reservoirs,” said Pellegrini, the study’s senior author.

Special soils

A rare type of wet ecosystem, peatlands form when waterlogged, oxygen-poor conditions cause plant matter to only partially decompose and accumulate. The result is the soft, spongy, usually dark soil dubbed peat. 

While not inherently more carbon-rich than wood, peat compacts over time. As a result, although peatlands cover only 3-4% of Earth’s land surface, they are estimated to hold about a third of all land-based carbon – roughly twice that of the world’s forests, according to the United Nations Environment Programme. 

With more than 10% of peatlands worldwide already drained or otherwise degraded, climate conservationists have targeted peatland restoration and maintenance as a promising nature-based climate solution. “Peatland preservation is a big issue for climate mitigation,” said Pellegrini.

Toward this end, Pellegrini’s Stanford colleagues Alison Hoyt and study co-author Alexandra Konings are leading a project focused on rewetting peatlands drained for agriculture in Indonesia to potentially slow carbon emissions and reduce wildfire risk. As peat soils dry out, the dead plants they accumulated over thousands of years start to rapidly decompose when they come into contact with oxygen, releasing carbon dioxide.

“Peatlands are found all over Earth, from the tropics to the Arctic Circle, and they each have distinctive characteristics and vulnerabilities when it comes to climate change,” said Pellegrini, the Volpi-Cupal Faculty Fellow in Climate and Nature-Based Solutions. “The outbreak of the Dava Moor Fire gave us a unique opportunity to study one of these fire-impacted peatlands up close.”

Into the burn scar

To learn more about wildfire sweeping across an area rich with peat in a temperate climate, Schoenecker traveled 10 hours by car to conduct a site visit of the burnt landscape in September 2025. At the time, she was a PhD student at Cambridge University, where Pellegrini was on the faculty before joining Stanford. 

With colleagues, Schoenecker measured how deep the fire burned into the soil at preselected locations on a grid to obtain a statistically meaningful sample size. To discern peat burn depth at each sampling point, the researchers measured the distance between the post-fire soil surface and the root tops of surface-rooting plant species that survived the fire. 

Alongside this hand-collected information, the researchers consulted readings of soil moisture taken remotely by NASA’s Soil Moisture Active Passive (SMAP) satellite to assess the state of the land before the megafire broke out. SMAP data indicated a dry winter and spring had created the conditions for the Dava Moor Fire to burn extremely hot and spread fast, although it was ignited by human activity.

“We’re concerned that this fire could indicate a shift in the UK’s fire regime toward these kinds of wildfires happening much more readily now,” said Pellegrini. “That, in turn, could have implications for the extensive peatlands found in other temperate and northern regions.”