Addressing methane emission feedbacks from global wetlandsDownload PDF Download PDF Brief CommunicationOpen accessPublished: 05 September 2025Emily A. Ury ORCID: orcid.org/0000-0002-1459-655X1 nAff4,Zhen Zhang ORCID: orcid.org/0000-0003-0899-11392 &Brian Buma ORCID: orcid.org/0000-0003-2402-77373 Nature Sustainability (2025)Cite this articleSubjectsCarbon cycleClimate-change ecologyClimate-change mitigationClimate-change policyAbstractEarth-system feedback loops that exacerbate climate warming cause concern for both climate accounting and progress towards meeting international climate agreements. Methane emissions from wetlands are on the rise owing to climate change—a large and difficult-to-abate source of greenhouse gas that may be considered indirectly anthropogenic. Here we illustrate the power of emissions reduction from any sector for slowing the progress of earth-system feedbacks.MainReducing anthropogenic greenhouse gas (GHG) emissions is critical to slow climate warming. However, some sources of emissions are particularly difficult to address. Although direct anthropogenic emissions (that is, using fossil fuels) are the fundamental sources of concern, indirect anthropogenic emissions from earth-system feedbacks in unmanaged lands are also increasing1. Permafrost thaw, wildfire and wetland methane emissions are three prominent examples of natural phenomenon that have accelerated in recent decades2,3,4. GHG emissions from these sources are typically diffuse and widespread, making them much more difficult to mitigate than point sources5. As the climate warms, these ecosystems will continue to emit more warming GHGs, contributing to substantial and increasing feedback loops1. As warming increases, these often unaccounted for climate feedbacks increasingly threaten climate policy ambitions6.It is clear that any reduction in the rate of global temperature rise can work to slow the pace of climate feedbacks. Reducing direct emissions can slow emissions from increased wildfire, permafrost thaw, wetlands and other ecological sources. A challenge in addressing these feedbacks lies in the communication of effective quantitative evidence to promote action. Like many climate-related topics, the discourse on climate feedbacks is typically reported in terms of additional carbon or CO2 (for example, Arctic permafrost7 or wetlands8), which is difficult for some audiences to conceptualize. Translation from units of carbon to impact on global temperature is clearer and more tractable to general audiences9,10. Furthermore, converting emissions or emissions reductions into temperature change shows the magnitude of these emissions with respect to climate targets such as those of the Paris Agreement (that is, limiting warming to 2 °C). This places the value of considering climate feedbacks into a policy-relevant and intuitive context, helping to further action for effective climate change mitigation.Wetlands contribute to climate change through their emissions of methane, a potent GHG, which are increasing under the warmer and wetter conditions brought on by climate change (Fig. 1)4,11. Rising methane emissions from wetlands are exceedingly difficult to mitigate directly; there are no demonstrated options for direct management at a global scale5. The well-characterized growth of wetland methane emissions with global temperature rise provides a unique opportunity to examine the role that climate change mitigation has in addressing earth-system feedbacks.Fig. 1: Conceptual drawing of the wetland-methane feedback.Positive feedback loop initiated by anthropogenic GHG emissions (black arrow) enhancing climate warming and leading to additional methane emissions from wetlands (grey arrow). Baseline (natural) CH4 emissions from wetlands (white arrow) remain unaffected, but all emissions contribute to the climate warming feedback loop. Arrows are not drawn to scale and do not represent the relative magnitude of GHG fluxes.Full size imageHere we reframe the conversation around climate feedback loops in two ways. First, we estimate the avoided methane emissions that can be achieved by slowing the wetland-methane feedback via reductions in anthropogenic GHG emissions. Second, we translate these emissions reductions into avoided warming in degrees Celsius, to show relevance towards the goals of the Paris Agreement. This perspective is not intended to trivialize the core challenge of reducing anthropogenic emissions. Our aim is to present a solutions-oriented lens for addressing emissions from climate feedbacks and put these findings into a policy-relevant context.Wetland methane emissions represent one of the largest earth-system feedback loops1,12 and are estimated to grow by an additional 23–277 Tg CH4 yr−1 by the end of this century4,11. This growth in methane emissions is attributed mainly to warmer temperatures enhancing microbial methane production in wetlands and hydrologic intensification leading to the expansion of wetland inundation extent and duration4,13. Using published relationships between wetland methane emissions and temperature4,11, we estimated the effect of emission-reducing measures on wetland methane (precipitation regime, CO2 fertilization and other effects of climate change are incorporated into the models of future wetland emissions used to derive the temperature–emission relationship4,11; Methods). Two large-scale climate change mitigating measures are investigated: (1) achieving net zero in the global transportation sector by 2050 and (2) achieving an aggressive CO2 emissions reduction pathway (Shared Socioeconomic Pathway (SSP) 1-1.9).To align with the Paris Agreement, achieving net zero across the global transportation sector is necessary by 2050, which would result in approximately 7,290 MtCO2 emissions reductions annually (based on worldwide transportation sector emissions in CO2 equivalents in 2020 and ignoring, for simplicity, other impacts such as manufacturing changes)14. We estimate that achieving a net-zero transportation sector by 2050 will result in 0.15 °C (95% confidence interval: 0.13–0.22 °C) of warming avoided (relative to SSP2-4.5) by the end of this century (Table 1), assuming that all other emissions remain consistent with the baseline projection. The avoided warming achieved through this effort would reduce climate-driven wetland methane production by 6.8–12.2 Tg CH4 yr−1 by 2100, which translates to 2.6–5.2% of additional warming avoided (by 2100), beyond the benefits of this intervention alone. We note that this additional warming avoided is just one of numerous earth-system feedback loops (for example, permafrost thaw, shifting ice sheet albedo, forest fire and so on) that might similarly be slowed; thus, the cumulative benefit is probably larger1.Table 1 Effect of climate change mitigation on feedback-derived wetland methane emissions and global temperature in 2100Full size tableBroad-scale climate change mitigation, such as CO2 reductions commensurate with a strong emissions reduction pathway (that is, SSP1-1.9), would have a strong effect on the wetland methane feedback15. This pathway reduces emissions of CO2 by about 20,000–40,000 MtCO2 yr−1 (ref. 16; Extended Data Table 1). We estimate that this magnitude of CO2 emissions reductions would result in approximately 1.1 °C (0.86–1.55 °C) of avoided warming (relative to SSP2-4.5) by 2100. This avoided warming would then result in a reduction of wetland methane emissions by 47–84 Tg yr−1 (Table 1) and further the avoided warming of the climate change mitigation measures by 4.0–7.6%. Differences between the two examples arise not only from the difference in magnitude (scale) of emissions reduction, but also the timing of the emissions reductions imposed in each of our scenarios (that is, reduction in transportation sector emissions are imposed uniformly from 2050 onwards versus the SSP1-1.9 emissions reductions that vary over time), which affects the extent of the effect realized by 2100.Here we assume that the relationship between global temperature and feedback strength is linear and consistent in the future4,11. Importantly, we do not simulate cooling or a warming reversal, but rather emissions avoided by reduced warming in the future, so a potential hysteretic effect need not be considered. We also note that the mode of atmospheric GHG reductions is immaterial (for example, fossil fuel reduction or direct air capture), as the effects are mediated through the net impact on global climate warming. The same effect could be achieved through the reduction of anthropogenic methane emissions, further amplifying the reach of these efforts. Not all feedback loops will respond equally to various mitigation measures, for example, those mediated through changes in surface albedo driven by black carbon emissions. Furthermore, not all climate feedback loops, or anthropogenic emissions, reinforce warming1. A prominent example is the methane-suppressing effect of sulfate deposition, derived from anthropogenic emissions17. As sulfate emissions decline with emission controls and other pollution reduction measures, methane emission suppression by sulfate in wetlands decreases17, potentially offsetting some of the avoided methane emissions illustrated in our analysis. This example emphasizes the importance of including climate feedback processes in earth-system modelling efforts and understanding the interactions between the various biogeochemical processes involved.We acknowledge that earth-system feedbacks have long been appreciated in the earth science community1 and that highlighting the need to reduce climate feedbacks is not new7,8. However, these phenomena have rarely been put into the actual units and contexts of direct experience and the Paris Agreement goals—degrees Celsius. Estimating how much additional temperature warming is avoided via reducing wetland methane emissions translates an abstract concept into lived experience. Our estimate—that for every degree Celsius of warming avoided by direct reductions in GHG emissions we achieve an additional 3–8% of warming avoided through wetlands alone—highlights the value of direct action. As noted, this estimate does not simulate cooling, only avoided warming. There is little to no knowledge of the reversibility of the wetland methane feedback, and no guarantee that all warming is reversable18, especially in complex earth systems. This frame of reference reinforces the importance of swift action for emissions reduction strategies, particularly if we aim to reduce the time to peak warming19. However, as many positive feedback loops, such as rising wetland methane, are not yet incorporated into global climate models16, the additional warming avoided cannot be included in global models, or even carbon budgeting, until these processes are fully accounted for. Nonetheless, translating the effect of these feedbacks into the more immediate and practical metric of degrees and direct management actions provides traction for policymakers and a baseline for how effective management can be in systems with coupled natural and anthropogenic emissions. Approaching feedback loops as coupled human–natural systems that can be managed in an integrated fashion alongside direct anthropogenic emissions offers a pathway for reaching global temperature goals that is consistent with realistic warming trajectories.MethodsDefining the temperature–methane emission relationshipTo translate the relationship between global temperature and wetland methane emissions into policy-relevant units, we use two recent projections of future wetland methane emissions under multiple climate change scenarios4,11. From these studies, we extracted the projected growth of wetland CH4 emissions as a function of temperature and the range of uncertainty for each, which are presented in our results (Extended Data Fig. 1 and Supplementary Information).Global temperature change for each emission scenario as a function of changes in methane was obtained from the Model for the Assessment of Greenhouse Gas Induced Climate Change (MAGICC, version 7)20. MAGICC is a reduced-complexity climate model that was accessed and run online from https://magicc.org, using the probabilistic configuration (100-member ensemble runs) to ascertain a range of parameter uncertainty on temperature outputs. A reduced-complexity model is an efficient way to perform analyses on small perturbations in GHG emissions that would be difficult to resolve in complex earth-system models.Accounting for additional wetland methane emissionsAs additional climate change-driven methane emissions from wetlands are not incorporated into the baseline MAGICC framework, these emissions can be introduced to establish a new baseline of future global temperature anomaly that is inclusive of these enhanced emissions. Note that change in wetland area dynamics, elevated atmospheric CO2 and altered precipitation regimes are incorporated into the projections of wetland methane emission as consequences of climate change and drivers of wetland methane emission4,11. This allows us to use temperature alone as a proxy for the suite of conditions, driven by climate change, that lead to enhanced wetland methane emissions.Climate change mitigation scenariosTwo broad-scale, policy-relevant climate change interventions were chosen to illustrate the effect of avoided warming on wetland methane emissions. First, we consider achieving net zero in global transportation as an illustration of climate change mitigation within an individual sector. Second, we examine the effect of aggressive, systemic change illustrated by CO2 emissions reductions conducive to achieving the goals of the Paris Agreement. Both of these climate change interventions are modelled in comparison to a ‘middle of the road’ baseline (SSP2-4.5) that is consistent with our current trajectory15,16. Supplementary Information provides additional details of the methods and assumptions used in this analysis.Evaluating the impact of climate change mitigationWe estimated the change in global temperature that would follow the direct emissions reductions scenarios (net-zero transportation and aggressive emissions reduction) using MAGICC, by imposing these emissions reductions on the model inputs. The resulting changes to global temperature are translated into a range of wetland methane emissions based on the relationship described above. Finally, the new wetland methane emission estimates are incorporated into overall global emissions and run through MAGICC to determine the overall effect on global temperature. Note that this does not reduce wetland methane emissions below current values but is a partial reduction of the projected additional methane emissions from wetlands due to climate change.Reporting summaryFurther information on research design is available in the Nature Portfolio Reporting Summary linked to this article.Data availabilityAll data used in this study are available in previously published studies. Source data are provided with this paper.Code availabilityCode used to reproduce the results presented in this paper is freely available via figshare at https://doi.org/10.6084/m9.figshare.26593153.v3 (ref. 21). Original code for data analysis was written by the authors and run in R (version 4.2.3).ReferencesRipple, W. J. et al. Many risky feedback loops amplify the need for climate action. One Earth 6, 86–91 (2023).Google Scholar Phillips, C. A. et al. Escalating carbon emissions from North American boreal forest wildfires and the climate mitigation potential of fire management. 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UryState Key Laboratory of Tibetan Plateau Earth System, Environment and Resource (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, ChinaZhen ZhangEnvironmental Defense Fund, Boulder, CO, USABrian BumaAuthorsEmily A. UryView author publicationsSearch author on:PubMed Google ScholarZhen ZhangView author publicationsSearch author on:PubMed Google ScholarBrian BumaView author publicationsSearch author on:PubMed Google ScholarContributionsE.A.U. and B.B. conceived the study. Z.Z. contributed data. E.A.U. performed the initial analysis and wrote the paper draft. Z.Z. and B.B. helped to refine the data analysis and revised the paper.Corresponding authorCorrespondence to Emily A. Ury.Ethics declarationsCompeting interestsThe authors declare no competing interests.Peer reviewPeer review informationNature Sustainability thanks Vincent Gauci and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.Additional informationPublisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Extended dataExtended Data Fig. 1 Linear relationships between global temperature anomaly and wetland methane emissions (2020-2099).Red points and line are from Zhang et al. [4] and black points and line are from Kleinen et al. [11]. Symbols represent various Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways (RCPs). Temperature anomaly over time is derived from baseline SSP scenario outputs from MAGICC. The low variance in Zhang et al. [4] is due to the averaging effect of the ensemble mean, which smooths out variations from individual model runs.Source dataExtended Data Table 1 Magic Model input adjustments for additional feedback methane and carbon dioxide under climate change mitigation scenariosFull size tableSupplementary informationSupplementary InformationSupplementary Fig. 1 and extended methods.Reporting SummarySource dataSource Data Extended Data Fig. 1Global temperature and wetland methane emission projections.Rights and permissionsOpen Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. 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