Aside from expanding his scientific interests, Rees has written and spoken extensively about the problems and challenges of the 21st century, and the interfaces between science, ethics, and politics. He is a member of the Board of the Institute for Advanced Study, in Princeton, the Oxford Martin School, and the Gates Cambridge Trust. He co-founded the Centre for the Study of Existential Risk and serves on the Scientific Advisory Board for the Future of Life Institute. He has formerly been a Trustee of the British Museum, the Science Museum and the Institute for Public Policy Research (IPPR).