Feasibility of peak temperature targets in light of institutional constraints

• Published in: Nature climate change 2024-08, Vol.14 (9), p.954-960
• Main Authors: Bertram, Christoph, Brutschin, Elina, Drouet, Laurent, Luderer, Gunnar, van Ruijven, Bas, Aleluia Reis, Lara, Baptista, Luiz Bernardo, de Boer, Harmen-Sytze, Cui, Ryna, Daioglou, Vassilis, Fosse, Florian, Fragkiadakis, Dimitris, Fricko, Oliver, Fujimori, Shinichiro, Hultman, Nate, Iyer, Gokul, Keramidas, Kimon, Krey, Volker, Kriegler, Elmar, Lamboll, Robin D., Mandaroux, Rahel, Rochedo, Pedro, Rogelj, Joeri, Schaeffer, Roberto, Silva, Diego, Tagomori, Isabela, van Vuuren, Detlef, Vrontisi, Zoi, Riahi, Keywan
• Format: Article
• Language: English
• Subjects: 639/4077/2790; 704/106/694/682; 706/4066/4076; 706/689/694/682; Carbon; Carbon dioxide; Carbon dioxide emissions; Carbon emissions; Clean energy; Clean technology; Climate Change; Climate Change/Climate Change Impacts; Constraining; Constraints; Cost effectiveness; Costs; Earth and Environmental Science; Emissions; Energy costs; Energy demand; Energy industry; Energy technology; Environment; Environmental Law/Policy/Ecojustice; Feasibility; Feasibility studies; Heat treating; Information management; Institutional constraints; Intercomparison; Mitigation; Net zero; Paris Agreement; Shadow prices; Technical feasibility; Technology assessment; Temperature requirements
• ISSN: 1758-678X; 1758-6798
• DOI: 10.1038/s41558-024-02073-4

Despite faster-than-expected progress in clean energy technology deployment, global annual CO 2 emissions have increased from 2020 to 2023. The feasibility of limiting warming to 1.5 °C is therefore questioned. Here we present a model intercomparison study that accounts for emissions trends until 2023 and compares cost-effective scenarios to alternative scenarios with institutional, geophysical and technological feasibility constraints and enablers informed by previous literature. Our results show that the most ambitious mitigation trajectories with updated climate information still manage to limit peak warming to below 1.6 °C (‘low overshoot’) with around 50% likelihood. However, feasibility constraints, especially in the institutional dimension, decrease this maximum likelihood considerably to 5–45%. Accelerated energy demand transformation can reduce costs for staying below 2 °C but have only a limited impact on further increasing the likelihood of limiting warming to 1.6 °C. Our study helps to establish a new benchmark of mitigation scenarios that goes beyond the dominant cost-effective scenario design. The Paris Agreement requires reaching net-zero carbon emissions, but a debate exists on how fast this can be achieved. This study establishes scenarios with different feasibility constraints and finds that the institutional dimension plays a key role for determining the feasible peak temperature.