Peat Combustion Drove 85% of Emissions from the UK's First Recorded Megafire

✅ Key Takeaway: The Dava Moor fire released as much carbon in four days as the UK's wildfires typically emit in a year, with peat combustion responsible for nearly 85% of the total.

A study published in Nature Geoscience has found that the Dava Moor fire of June 2025 - the UK's first recorded megafire under the standard 10,000-hectare threshold - released an estimated 38,600 tonnes of carbon, with peat combustion responsible for nearly 85% of the total.

Coincidentally, that figure equals 85% of the entire mean annual UK fire emissions recorded across 2001–2021. It came from a single fire that burned for four days.

The Cambridge-led team also found there was unusually heavy vegetation on the ground heading into June - well above what's typical for the time of year - and that common heathland plants, which burn easily, likely made the fire worse.

The soil was far drier than usual for the time of year. That combination - bone-dry peat underground and an unusual build-up of vegetation on top - let the flames burn down into soils that would normally be too wet to catch fire.

Where the carbon came from

The team mapped the fire using Sentinel-2 satellite imagery and ground-truthed peat burn depth at 106 sampling points roughly two months after the fire. Across the 10,000-hectare burn area:

• Moorlands and heathlands accounted for 83% of the area burned. Most of the carbon released from these areas came from belowground peat, not aboveground vegetation.

• Bogs (defined in the UK land cover map as peat deeper than 0.5 metres) accounted for 10% of the burned area. Within bogs, 58% of the area burned at high severity, and 73% of bog emissions came from peat.

• Forests, woodlands and other land cover made up the remaining 6%.

Field sampling confirmed peat was present at 100% of random sampling points across all vegetation types - including moorland and heathland areas, not only in formally mapped bogs. Peat combustion was not confined to the deep-peat zones regulators typically focus on.

The team's central estimate of 38,600 tonnes is field-constrained, drawing on 106 peat burn depth measurements taken roughly two months after the fire. Sensitivity testing in the paper indicates that under higher combustion-completeness assumptions, total emissions could have reached 119,000 tonnes. Two independent modelling approaches produced figures within this range.

Climate signal, fuel signal

The paper is direct about the climatic backdrop. The 2024–2025 winter was low in precipitation; fire-weather conditions across the area in May 2025 were notably worse than the ten-year norm. The authors cite projections that European fire weather will rise by 24% by 2050 even under low-emission scenarios, and that UK droughts are projected to shift from once every 20 years to once every 3 years by 2040.

But climate is not the only signal in the paper. The unusually heavy build-up of vegetation going into the fire - well above the ten-year norm - is treated as a real contributor to how fast it spread, not a side note.

The authors also identify flammable heathland species as a factor in the high severity. For moorland managers, this is the operative finding: dry conditions primed the system, but accumulated fuel let the fire travel.

Implications for the regulatory debate

The 2021 regulations restricting prescribed burning on deep peat in England were framed around carbon protection, the premise being that fire on deep peat releases stored carbon.

The Dava Moor study confirms that wildfire on dry peat does exactly that, at a scale this fire alone equalled most of a typical year's national fire emissions. The same study identifies anomalous fuel accumulation as a contributing factor to fire severity, and finds peat present and combustible in moorland and heathland areas outside the formally mapped deep-peat zones.

Peat carbon is classified in the literature as "irrecoverable" on policy-relevant timescales: recovery takes decades to centuries, well beyond the net-zero horizon.

Prescribed burning of surface vegetation conducted under cool and damp conditions does not penetrate to peat. Wildfire under the conditions documented at Dava Moor does. The two are not equivalent carbon events, and this paper provides field-measured data to say so.

The Dava Moor fire happened under exceptional climatic conditions, and the authors are clear that such conditions are projected to become more common. But climate alone did not produce a 10,000-hectare burn.

An unusually heavy build-up of vegetation, and the fact that common heathland plants burn easily, are flagged in the paper as contributing factors too - on top of the dried-out peat underneath. Reducing the wildfire risk that this paper documents means addressing what burns, not only the weather that lets it burn.