William Rees is a human ecologist, ecological economist, Professor Emeritus and former Director of the University of British Columbia’s School of Community and Regional Planning in Vancouver, Canada, where his research and teaching focused on the biophysical prerequisites for sustainability in an era of accelerating ecological change. Within this envelope developed a special interest in ecologically-relevant metrics of sustainability and their interpretation in terms of complexity theory and behavioural ecology. Prof Rees is perhaps best known in ecological economics as the originator and co-developer of ‘ecological footprint analysis’. His book on eco-footprinting, with then PhD student Dr Mathis Wackernagel, has been translated into eight languages including Chinese. Widely adopted for sustainability assessments by Governments, NGOs and academics, the human ‘eco-footprint’ has arguably become world’s best-known sustainability indicator. Prof Rees’ most recent writing focuses on neuro-biological, cognitive and cultural barriers to sustainability, including human’s well-developed capacity for self-delusion. He has authored (or co-authored) more than 150 peer reviewed papers and book chapters, and numerous popular articles on humanity’s (un)sustainability conundrum. Active across disciplines, Dr Rees is a long-term member of the Global Ecological Integrity Group, a Fellow of the Post-Carbon Institute, a founding member and past President of the Canadian Society for Ecological Economics and founding Director of the OneEarth Initiative. The influence of Dr Rees’ work is widely recognized and awarded. He has lectured by invitation throughout North America and 25 other countries around the world; the Vancouver Sun named Prof Rees one of British Columbia’s top public intellectuals in 2000; in 2006 he was elected to the Royal Society of Canada and in 2007 he was awarded a prestigious Trudeau Foundation Fellowship. Laval University in Québec recognized Prof Rees with an honorary doctorate in 2012, and he is the recipient of both the 2012 Boulding Prize in Ecological Economics and a 2012 Blue Planet Prize (jointly with Dr Wackernagel).