LETTER Political leadership, climate policy, and renewable energy Jeroen C. J. M. van den Bergha,b,c,d,1 and Ivan Savina,e Martinez-Alvarez et al. (1) conclude that the impact of encouraging renewables and reducing net emissions (5). political leaders on carbon pricing has been limited. Their Fifth, subsidies promote energy/carbon rebound, estimated study has, however, two serious shortcomings: 1) It excludes at the macroscale to equal possibly 50 to 100% (6). Carbon the 6-y period since the Paris Agreement entered into force pricing appears to be the only effective way to limit (on 4 November 2016), during which many jurisdictions rebound (7). Given these considerations, it is hardly surpris- implemented or strengthened carbon pricing; and 2) it limits ing that historical absence of carbon pricing resulted in itself to gasoline taxes while not accounting for genuine low-carbon sources displacing only one-tenth of fossil-fu- carbon pricing, notably applied to large industrial emitters. el-generated electricity (8). Among others, it ignores the European Union's emissions- Renewable subsidies are thus a far cry from effective trading system (EU-ETS), the most successful carbon-pricing climate policy. The fundamental reason is that climate solu- instrument worldwide, with a price fluctuating around tions are prone to free riding: Sacrifices are (perceived as) 80€/TCO2 since early 2021. In effect, the study focuses on large, while gains are uncertain, small, and delayed—for both emissions of fossil-fuel use by transport, representing only individuals and countries. The EU-ETS demonstrates that a some 15% of global emissions. Moreover, since general supranational approach harmonizing national climate policies fuel taxes are not proportional to carbon content of fuels, is the way forward to overcome free riding. The EU could invite they provide an inaccurate incentive for CO2 emissions the United States and China to join its ETS (9). This would sim- reduction. Finally, the study’s use of ordinary least squares plify negotiations to only three partners—compared to almost may have biased its results as it is sensitive to outliers— 200 countries in post-Paris negotiations under auspices of the visible in the plots of average monthly changes in fuel taxes United Nations. The resulting China-EU-US climate club with (Supporting Information). The literature suggests using least a joint carbon price and border tariff might trigger a domino absolute deviation or quantile regression as these avoid effect (10). Indeed, few countries would want to remain out- assumptions of homoscedasticity and normally distributed side such a powerful club. This is arguably the most realistic Downloaded from https://www.pnas.org by 158.109.161.56 on March 28, 2023 from IP address 158.109.161.56. errors. Altogether, the pessimistic policy conclusion rests scenario for solving climate change. upon feeble grounds. ACKNOWLEDGMENTS. ERC Grant 741087 from the European Research Council Next, the authors’ advice is to shift the policy focus to in the European Union’s Horizon 2020 program provided financial support. subsidies for renewable energy. This is unconvincing as they did not undertake a comparable analysis for such subsidies while five substantive arguments plead against them. First, Author affiliations: aInstitute of Environmental Science and Technology, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain; bICREA, Barcelona 08010, Spain; the pace of renewable-energy diffusion will be insufficient c School of Business and Economics, VU University Amsterdam, Amsterdam 1081 HV, The to meet the Paris targets without major changes in produc- Netherlands; dInstitute for Environmental Studies, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands; and eGraduate School of Economics and Management, Ural tion and consumption structures (2). Second, renewables’ Federal University, Yekaterinburg 620075, Russian Federation infrastructure requires considerable fossil-fuel inputs that will contribute to CO2 emissions (3). Third, production- Author contributions: J.C.J.M.v.d.B. and I.S. wrote the paper. related emissions of renewables differ between technolo- The authors declare no competing interest. gies and countries (4). Since without carbon pricing their Copyright © 2023 the Author(s). Published by PNAS. This article is distributed under sales prices will not reflect such differences, users are not Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND). encouraged to minimize life-cycle emissions. Fourth, studies 1 To whom correspondence may be addressed. Email: jeroen.bergh@uab.es. show that carbon pricing is more effective in both Published March 27, 2023. 1. C. B. Martinez-Alvarez, C. Hazlett, P. Mahdavi, M. L. Ross, Political leadership has limited impact on fossil fuel taxes and subsidies. Proc. Natl. Acad. Sci. U.S.A. 119, e2208024119 (2022). 2. A. Arvesen, R. M. Bright, E. G. Hertwich, Considering only first-order effects? How simplifications lead to unrealistic technology optimism in climate change mitigation. Energy Policy 39, 7448–7454 (2011). 3. A. Slameršak, G. Kallis, D. W. O’Neill, Energy requirements and carbon emissions for a low-carbon energy transition. 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