Permafrost, wetland, wildfire and freshwater emissions could amplify climate change by up to 30%, study finds

A study in Environmental Research Letters finds that greenhouse gases from four natural sources — thawing permafrost, warming wetlands, freshwater systems, and wildfires — could add another 0.2 to 0.4 degrees Celsius of warming by 2100, amplifying human-caused warming since 2020 by 20 to 30%. Methane accounts for roughly half of that extra heat.

The researchers note that of the 11 Earth system models the IPCC used in its latest assessment, none included warming-driven emissions from wetlands or freshwater, only two included permafrost, and just five included wildfires — meaning current warming projections and the remaining 'carbon budget' are likely too optimistic.

The study's authors caution their estimate could run either high or low: it may overstate warming by ignoring vegetation regrowth, but could also understate it, since one comparison study found wetland methane release per degree of warming nearly double what they used. The U.S., the world's second-largest emitter, withdrew from the Paris Agreement for a second time in January 2026.

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