A new IIASA-led study examines growing critiques of how global climate mitigation scenarios address equity and justice and identifies key conditions for fair, feasible, and politically credible climate action.
Global climate mitigation scenarios shape real-world policy choices of who cuts emissions, who pays, and who benefits from climate action. A new IIASA-led essay published in PLOS Climate identifies how these influential tools address equity and justice, with implications for perceptions of fairness and public trust in climate policy. Drawing on a broad grassroots community process, the study identifies practical ways to advance equity and justice in climate mitigation pathways, supporting fair, feasible, and politically credible climate action.
The research synthesizes growing evidence that current scenarios fall short in reflecting unequal responsibilities, capacities, and development needs across regions and proposes a roadmap for integrating fairness into future climate pathways. According to lead author Shonali Pachauri, Transformative Institutional and Social Solutions Research Group Leader at IIASA, the study was motivated by the need to bring together fragmented critiques of climate mitigation modeling and modelers, and to move the discussion forward on how to integrate fairness into future scenarios.
“We wanted to bring together existing critiques, assess where current approaches fall short and where current scenarios already go further than some critiques suggest, and to set out a clear agenda for embedding equity and justice into climate mitigation futures,” she explains.
Instead of asking whether models should address equity, the authors focus on how to do so in practice.
“We focus on what needs to change in scenario design, modeling practices, and research processes,” notes coauthor Caroline Zimm, a senior research scholar in the same research group at IIASA.
The paper identifies three broad types of limitations in current climate mitigation scenarios:
- Structural limitations relate to who builds models and whose perspectives count.
- Methodological issues arise from a strong emphasis on cost efficiency, which often sidelines fairness and distributional impacts.
- Epistemological limitations refer to challenges in representing justice at policy-relevant scales.
Building on this diagnosis, the authors propose practical next steps, including:
- embedding effort sharing, and climate finance directly into scenarios
- safeguarding decent living standards for all
- expanding demand-side solutions
- involving underrepresented regions and communities in scenario design
“We highlight a research agenda that combines incremental improvements, deeper structural reforms, and participatory approaches that is designed to be practical as well as ambitious,” says coauthor Joeri Roglj, a senior researcher in the IIASA Energy, Climate, and Environment Program, Director of Research at the Grantham Institute, and Professor of Climate Science and Policy at the Centre for Environmental Policy at Imperial College London.
Importantly, the authors emphasize that many of the advances can be pursued within existing modeling efforts, while others point toward longer-term structural changes in the field.
Rather than offering a single technical fix, the study reframes climate mitigation modeling and scenario development itself. The authors clearly distinguish between incremental improvements and fundamentally new approaches, while recognizing the limits of models in resolving political questions of justice.
“Models are indispensable tools, but they cannot replace deliberative negotiation or moral judgment. Transparency, pluralism, and co-production are just as important as technical sophistication,” says Pachauri.
The implications of this work are significant for both policymakers and the public. For policymakers, the findings underscore that climate scenarios are not value-neutral and should be interpreted with a clear understanding of the normative assumptions embedded within them. Embedding equity directly into scenarios could help governments design fairer climate targets, estimate climate finance needs more accurately, and build stronger international cooperation grounded in shared responsibility. The work also highlights that climate pathways are not just technical exercises but also inform choices about how the burdens and benefits of climate action are shared, shaping livelihoods, development opportunities, and intergenerational justice.
Without fairness, even technically feasible climate pathways may fail politically. Equity-focused scenarios can strengthen trust, reduce conflict, and unlock broader public support for climate action. By offering concrete pathways to integrate justice concerns into modeling, the paper aims to strengthen the relevance and credibility of climate science at a time when global cooperation is both essential and fragile.
“Climate mitigation scenarios shape what policymakers believe is possible and acceptable. They are visions of who gets what future. Greater attention to equity can help ensure these pathways are robust, transparent, and socially grounded,” concludes study coauthor and IIASA Energy, Climate, and Environment Program Director, Keywan Riahi.
About IIASA:
The International Institute for Applied Systems Analysis (IIASA) is an international scientific institute that conducts research into the critical issues of global environmental, economic, technological, and social change that we face in the twenty-first century. Our findings provide valuable options to policymakers to shape the future of our changing world. IIASA is independent and funded by prestigious research funding agencies in Africa, the Americas, Asia, and Europe. www.iiasa.ac.at
