William Rees is a population ecologist, ecological economist, Professor Emeritus, and former Director of the University of British Columbia’s School of Community and Regional Planning. His research focuses on the biophysical requirements for sustainability and the implications of global ecological trends for the human prospect, and he has authored hundreds of peer-reviewed and popular articles. He is best known as the originator and co-developer (with his graduate students) of “ecological footprint analysis,” which shows that the world is far into overshoot. Dr Rees has authored. He is a founding member and former President of the Canadian Society for Ecological Economics; a founding Director of the OneEarth Initiative; and a Fellow of the Post-Carbon Institute. He is a Fellow of Royal Society of Canada, recipient of a Trudeau Foundation Fellowship and both the international Boulding Prize in Ecological Economics and a Blue Planet Prize (jointly with Dr Mathis Wackernagel). He holds a PhD in population ecology from the University of Toronto.