Jean-Pascal van Ypersele (Twitter: @JPvanYpersele) is emeritus full professor of climatology and sustainable development sciences at Université catholique de Louvain, member of the Académie royale de Belgique and of the Federal Council for Sustainable Development. A physicist and climate modeller who worked at the US National Center for Atmospheric Research, he has published with natural and social scientists about climate change and sustainable development at global and regional scales for forty years. He has been extensively involved in the IPCC since 1995, and was IPCC Vice-Chair from 2008 to 2015. He co-authored the first quadrennial UN Global Sustainable Development Report (2019), and was a member of the EU Mission Board on Adaptation to Climate Change, including Societal Transformation (2019-2021). He has participated to most UN conferences on climate issues since 1979, including almost all COPs (adviser to the Belgian delegation, and to the Fiji COP23 Presidency). He regularly briefs Heads of State and government, business, and stakeholders, and is occasionally consulted by Greta Thunberg.