Graduate HEC (1971), Phd in Social Sciences in 1977, State Phd in economics in 1984. Research Director Emeritus at the CNRS (Centre National de la Recherche Scientifique) and at the EHESS (Ecole des Hautes Etudes en Sciences Sociales). Director of the CIRED (Centre International de Recherche sur l’Environnement et le Développement), Professeur at the ENPC (Ecole Nationale des Ponts et Chaussées), member of the French National Committee of Scientific Research (1991-1999).
Member of the French delegation to the Climate Convention between 1995 and 2001 and from 2015 to 2019. Convening Lead Author for the Second and Third Assessment Report of the IPCC (1993-1996; 1999 – 2002). Lead Author for the Fourth and Fifth Assessment Report of the IPCC (2004-2007; 2011-2014) and for the IPCC 1.5 °C special report, author of the synthesis report of the sixth assessment report of the IPCC.