Severely burned peatlands may cut methane after rewetting

A study in Environmental Science and Ecotechnology suggests that peatlands hit hardest by wildfire may be the best candidates for restoration because they emit far less methane after rewetting than unburned or lightly burned soils. The finding could help land managers prioritize degraded peatlands that are both easier to restore and less likely to create a methane surge.

Why it matters: - Peatlands hold about one-quarter of global soil carbon, so restoring them can affect climate emissions at large scale. - Rewetting often reduces carbon dioxide losses but can raise methane, which has delayed some restoration efforts. - Severely burned peatlands may avoid much of that methane penalty, making them stronger candidates for climate-focused restoration. - Burned peatlands also tend to have less agricultural value, which can reduce land-use conflicts.

What happened: - Researchers at Aarhus University reported in Environmental Science and Ecotechnology on July 29, 2026, that severely burned peat soils emitted far less methane after rewetting than unburned or mildly burned soils. - The team ran a 90-day laboratory incubation using drained peat soils and rewetted soils that were unburned, mildly burned or severely burned. - The experiment measured carbon dioxide and methane emissions, soil chemistry and microbial communities. - The paper identifies a potential restoration strategy that links wildfire history with greenhouse gas outcomes.

The details: - Rewetting unburned peat caused methane emissions to rise about 40 times compared with drained soils. - Mildly burned soils produced even more methane, with emissions six times higher than rewetted unburned soils. - Severely burned soils showed methane emissions that stayed low and were statistically similar to drained controls. - That outcome translated to a 91% reduction in methane versus unburned rewetted soils. - Fourier-transform infrared spectroscopy found more recalcitrant carbon compounds in severely burned soils, including phenols and aromatics. - Mild fires did not substantially change carbon chemistry, but they may have released labile carbon by breaking down soil aggregates. - Severe fires increased soil pH and electrical conductivity, both of which were negatively correlated with methane emissions. - The abundance of mcrA, a key methane-production gene, dropped sharply in severely burned soils. - Methanogen communities were more active in mildly burned soils. - The authors said severe fires can alter peat so much that the usual methane response to rewetting does not occur. - The study DOI is 10.1016/j.ese.2026.100735.

Between the lines: - The result does not mean wildfire is beneficial overall. - It suggests that severe fire can create a narrower window where rewetting delivers climate gains with less methane downside. - The practical appeal is as much about land availability as chemistry, since fire-damaged peatlands may be easier to take out of production. - The researchers estimate more than 6 million hectares of peatlands burn each year worldwide. - They say 0.5 million to 0.9 million hectares of those burned areas are degraded peatlands that could be rewetted. - Prioritizing those areas could reduce methane by 0.1 million to 0.8 million tonnes of carbon dioxide equivalent annually under a 100-year global warming potential framework.

What's next: - Land managers and restoration planners may use fire history to identify peatlands where rewetting offers the best climate return. - The findings could support larger-scale restoration on degraded peatlands where farming opposition is already weaker. - Further field studies will likely be needed to test whether the laboratory results hold in real landscapes and over longer periods. - The work was supported by the European Union’s Horizon Europe programme and the China Scholarship Council.