This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: New research shows that warming-induced emissions—greenhouse gas emissions from natural sources driven by rising temperatures—could amplify global warming by approximately 20%–30% and add an estimated 0.2°C–0.4°C of warming this century on top of anthropogenic warming under different scenarios. These major additional drivers of warming are largely unaccounted for in current climate projections and policies.
Scientists have long anticipated that rising temperatures could trigger more emissions from natural sources, which in turn would lead to even more warming. Examples include thawing permafrost causing ancient frozen organic matter to decompose, warmer wetlands and lakes releasing more methane (especially in the tropics), and drier conditions fueling bigger wildfires that burn through carbon stored in forests. The paper, titled "Projected amplification of global warming by warming-induced greenhouse gas emissions," published in Environmental Research Letters, represents the largest effort to date to quantify the combined impact of four major feedbacks (for both carbon dioxide and methane) from permafrost thaw, wildfires, wetlands and inland waters.
The authors of the paper include leading researchers from institutions including Stanford University, Spark Climate Solutions, Environmental Defense Fund and Woodwell Climate Research Center. Even once emissions from human activities reach net-zero, greenhouse gas feedbacks could still add an estimated 0.2°C (1 standard deviation: ±0.2°C) of warming by 2100 under a stronger climate action scenario (SSP1-2.6). Under a scenario with higher emissions (SSP4-6.0), they could add an estimated 0.4°C (1 standard deviation: ±0.2°C) by 2100.
Critically, these warming-induced emissions remain largely absent from most Earth system models used to estimate the response of temperature to anthropogenic emissions. This means that current climate projections likely underestimate future warming. Scientists from around the world are convening to fill this gap by comparing different models of warming-induced emissions and advocating that these emissions be reflected in key policy and planning processes such as IPCC assessments.
The good news is, it's not too late to avert the worst impacts. The amount of warming that comes from these natural systems is directly related to the amount of warming from human-caused direct emissions—meaning if direct emissions decline, so too do these warming-induced emissions. "What surprised us was the size of the feedback: we found that natural systems could amplify global warming by 20% to 30%.
This hidden multiplier is missing from the models guiding climate policy, so those models are likely underestimating how much warming is coming—and overestimating how much carbon we can still afford to emit. To close that gap, we need to understand these processes better and build them into the models we rely on," says Spark Climate Solutions research scientist Dr. Sam Abernethy, the paper's lead author.
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