Future warming-induced emissions are substantial and poorly constrained

Earth-system feedback loops involving natural greenhouse gas emissions pose substantial but poorly constrained risks to future climate trajectories. While direct anthropogenic emissions dominate current climate policy, warming-induced emissions (WIE) from natural sources—including wetlands, permafrost, freshwaters, and wildfires—represent positive feedbacks that have a net effect of amplifying warming yet remain largely excluded from emissions accounting and climate projections. Here we synthesize literature-derived temperature-emission relationships for multiple natural sources and quantify their contributions to future emissions and temperature trajectories across three SSP scenarios (SSP1-2.6, SSP2-4.5, SSP4-6.0) through 2100.

We extracted relationships between global temperature and rising emissions of wetland CH₄, freshwater CH₄, and wildfire CO₂, while for permafrost CH₄ and CO₂ we used existing data from the literature for each SSP. We then used MAGICC7 to obtain baseline temperature trajectories, calculated the corresponding WIE using the derived relationships, and reran MAGICC with these additional emissions to quantify feedback-driven temperature increases. 

By 2100, preliminary estimates of total warming-induced methane emissions could range from 70 ± 40 Mt CH₄/yr under SSP1-2.6 to 200 ± 70 Mt CH₄/yr under SSP4-6.0, representing substantial fractions of current anthropogenic methane emissions. WIE of CH4 and CO2 contribute an additional 0.2 ± 0.1 °C of warming under a low-emission scenario (SSP1-2.6) and 0.5 ± 0.1 °C under a high-emission scenario (SSP4-6.0) by 2100. High uncertainty in each WIE highlights the need for improved process understanding and observational constraints.

Our results demonstrate that WIE represent a significant and growing component of the global carbon budget that cannot be ignored in climate accounting or policy frameworks. The magnitude of these feedbacks underscores the critical value of rapid emissions reductions in limiting not only direct warming but also the amplification of natural emissions. These findings provide policy-relevant quantification of WIE impacts and establish a baseline for future coupled earth-system modeling efforts such as WIE-MIP.