Marc Fleurbaey & Stéphane Zuber, Climate policies deserve a negative discount rate, FMSH-WP-2012-19, september 2012.
Nous défendons une méthodologie de l’actualisation, pour l’évaluation des effets à long terme des politiques climatiques, qui repose sur un objectif de bien-être social, contre l’idée que le taux de rendement du marché doit être utilisé à cette fin. Nous montrons aussi que dans le long terme, le taux d’actualisation pour de telles politiques devrait se concentrer sur le scénario le plus défavorable pour les populations les plus défavorisées. En conséquence, il est probable que le taux d’actualisation approprié pour les politiques climatiques doive être négatif, ce qui implique une grande priorité pour le futur.
taux d’escompte, politique climatique, équité intergénérationnelle
We defend a methodology of discounting, for the evaluation of the long-term effects of climate policies, which relies on a social welfare objective, against the view that the market rate of return should be used for that purpose. We also show that in the long run, the discount rate for such policies should focus on the worst-case scenario for the most disadvantaged populations. As a consequence, it is likely that the appropriate discount rate for climate policies should be negative, implying a high priority for the future.
discounting, climate policy, intergenerational equity
Marc Fleurbaey is Robert E. Kuenne Professor at the University of Princeton (USA) and holds the Chaire “Welfare Economics and Social Justice” at the Collège d’études mondiales (Fondation Maison des sciences de l’homme, Paris). His research in economics and philosophy has been devoted to normative economics, distributive justice, and the evaluation of public policy. The main areas of application are the measurement of social welfare, climate policies, health prioritizing, and optimal taxation. He has been professor of economics and CNRS researcher in France. He is the coordinating editor of Social Choice and Welfare and a former editor of Economics and Philosophy. He is a Coordinating Lead Author for the Fifth Assessment Report (2014) of the Intergovernmental Panel on Climate Change. He has been a member of the Stiglitz-Sen-Fitoussi Commission on the Measurement of Economic Performance and Social Progress. He has published Fairness, Responsibility, and Welfare (Oxford 2008) and A Theory of Fairness and Social Welfare (Cambridge 2011, with F. Maniquet), as well as many articles in welfare economics, public economics, and political philosophy.
Stéphane Zuber is an economist at Centre de Recherche Sens, Ethique et Societe (CERSES) in Paris and coordinator of the Chaire “Welfare Economics and Social Justice” at the Collège d’études mondiales (Fondation Maison des sciences de l’homme, Paris). He got his PhD in Economics at Toulouse School of Economics. He works on issues of intergenerational equity and climate policy with a focus on the problem of climate related risks: how to design equitable climate policies in an uncertain world and how to deal with catastrophic and correlated risks. His current research is how to change standard ex ante evaluations of risk, taking into account fairness issues of intra- and intergenerational equity. He also works on rank-discounted utilitarianism and its implications for climate policy and population ethics. He has published several research papers in journals such as the Journal of Economic Theory, the International Economic Review and Social Choice and Welfare.
This paper was written for the workshop on “Climate Change Justice”, Chicago, May 2012.
The authors have benefited from comments by G. Asheim, D. Weisbach (who in particular encouraged us to examine risky returns to investment), and the participants at the workshop on “Climate Change Justice”.