William E. Rees

William E. (Bill) Rees, PhD, FRSC, is a Canadian [[Human ecology|human ecologist, [1] ecological economist[[Human ecology| [2] and Professor Emeritus at the University of British Columbia in Vancouver, Canada, where he taught and conducted interdisciplinary research for more than four decades. He is perhaps best known for co-developing the ecological footprint concept and method of analysis with his graduate students. This quantitative tool estimates humanity's demand on nature, through measurable flows of energy and materials to and from ecosystems; it thus reinforces associated concepts such as ecological limits and biocapacity, and shows clearly that the human enterprise is in a state of advanced ecological overshoot. Rees' work has long focused on the relationship between the human enterprise and the ecosphere, sustainability, human carrying capacity, over-exploitation, ecological overshoot, and urban systems and on cognitive barriers to understanding the depth of our eco-predicament. He has authored or co-authored hundreds of peer-reviewed papers and popular articles on these issues. His work is taken up by governments, nongovernmental organizations, educators, and scholars internationally.…

William E. (Bill) Rees, PhD, FRSC, is a Canadian [[Human ecology|human ecologist, [1] ]] ecological economist[[Human ecology| [2] ]] and Professor Emeritus at the University of British Columbia in Vancouver, Canada, where he taught and conducted interdisciplinary research for more than four decades. He is perhaps best known for co-developing the ecological footprint concept and method of analysis with his graduate students. This quantitative tool estimates humanity's demand on nature, through measurable flows of energy and materials to and from ecosystems; it thus reinforces associated concepts such as ecological limits and biocapacity, and shows clearly that the human enterprise is in a state of advanced ecological overshoot. Rees' work has long focused on the relationship between the human enterprise and the ecosphere, sustainability, human carrying capacity, over-exploitation, ecological overshoot, and urban systems and on cognitive barriers to understanding the depth of our eco-predicament. He has authored or co-authored hundreds of peer-reviewed papers and popular articles on these issues. His work is taken up by governments, nongovernmental organizations, educators, and scholars internationally. Rees has been a member of various sustainability-oriented organizations, including the Canadian Society for Ecological Economics (co-founder and past-president), OneEarth Living (co-founder), the Post Carbon Institute, and the Club of Rome. Rees' contributions are widely recognized. He was elected a Fellow of the Royal Society of Canada and received a Pierre Elliott Trudeau Foundation Fellowship. Honours include the Blue Planet Prize (shared with his former student Mathis Wackernagel), the ISEE Kenneth Boulding Award for Ecological Economics, the Herman Daly Award, and an honorary doctorate from Université Laval. He also held senior administrative roles at UBC, including Director of the School of Community and Regional Planning (SCARP).

Background

Background / Youth William E. (Bill) Rees was born on December 18, 1943, in Brandon, Manitoba, Canada, and spent his early childhood in Montreal, Quebec, and later in Toronto, Ontario. Many of his most formative experiences took place on his grandparents' farm in southern Ontario, where he began to experience and understand humans as a species within many ecosystems. With various cousins, Rees worked the market garden, picked apples, fed and "dusted" the chickens, pitch-forked hay onto a horse-drawn wagon, and went fishing when the day's work was done. On one occasion after the day's exertions, a ten-year old 'Billy' was sitting at his Grandmother's dinner table, staring absently at the food heaped on his plate. "My subconscious must have been grinding away because it suddenly struck me that I had had a hand in raising everything I was about to eat. Trivial observation? Perhaps, but with it came an unexpected rush of emotion including a profound insight. I knew deep in my bones that farm work and food made me a product of sun and soil. I acquired a very personal understanding that we are, quite literally, what we eat. No science there. This was the experience of raw truth, my personal epiphany." Since then, Rees has been concerned that few young people today have an opportunity to be "up close and personal" with the ecosystems that support them – and thus have never come to feel "in their bones" that they are part of nature. Undergraduate studies Rees first earned an undergraduate degree (B.Sc.) in Zoology from the University of Toronto. This foundational study of animal biology and ecosystems provided the groundwork for his later explorations of human ecology, carrying capacity and biophysical limits. Ph.D in Population Ecology (University of Toronto) Continuing his education with a scholarship to the University of Toronto, Rees earned his Ph.D. in population ecology. His fieldwork and academic courses equipped him with the conceptual and analytical tools to study population dynamics in relation to biocapacity, inter- and intra-specific competition, the interplay of positive and negative feedback, and how these factors ultimately impose limits on population and material growth. It also infused him with a lasting fascination with society's general ignorance of the biophysical foundations of its own existence. Thus equipped, Rees joined the University of British Columbia (UBC) in September 1969, initially with a joint appointment as assistant professor in the School of Community and Regional Planning (SCARP) and the (former) Institute of Animal Resource Ecology. Early academic Experience Rees was assigned the task of developing an "ecological planning" stream in SCARP, beginning with courses on the ecological basis for planning and on ecological land-use planning. His early research focused on the application of environmental impact assessment in Canada, but his background in ecology helped him maintain his broad interest in the biophysical requirements for human sustainability. Shortly after joining UBC, Dr. Rees was appointed to an interdisciplinary committee tasked with establishing the parameters for a proposed new water-oriented research centre. He was asked to explain his research interests and potential contribution to the new centre. Rees presented a seminar to the committee on human carrying capacity and the relevance of the concept to water resource management. A senior colleague (one of Canada's foremost resource economists) later took him aside and warned him that, should he pursue this line of research, his career at UBC would be a Hobbesian "nasty, brutish and short." Apparently, economists had negated the concept of carrying capacity as applied to Homo sapiens. This was Rees' introduction to the assumptions of neoliberal economics that the human enterprise operates separately from, and largely independent of, nature. His economist colleague told him that "human ingenuity (read 'technology') is the greatest resource" and that any residual local resource limits could be overcome through trade, at least until technology came to the rescue. Despite this initial discouragement, Rees continued to dwell on the humanity-nature connection, convinced that the material assumptions of neoliberal economic theory were deeply flawed. This instinct was buoyed by the early ecology-oriented publications of renegade economist Herman Daly, one of the fathers of ecological economics (and who subsequently became a collaborator and friend). Rees was encouraged enough to develop a special focus on the material ecology of modern cities. He came to view them as massive "dissipative structures" that can be sustained only by the continuous consumption/dissipation of low-entropy energy and matter and the production of entropic waste. This urban metabolism makes cities essentially parasitic on the ecosphere; at best, they are the eco-dependent consumptive components of the total human ecosystem and thus highly vulnerable to adverse global change. People are generally unaware that the bio-productive components of human urban ecosystems are actually rural hinterlands, increasingly dispersed across the planet by trade. He would ask his urban planning students: "What would happen to a city's millions of inhabitants if cut off from their supportive ecosystems?" Instead of viewing human settlements as isolated from nature, his research began to map the massive, unseen flows of energy and materials extracted from the ecosphere and required to sustain urban populations, as well as the equal flow of useless waste injected back into the ecosphere. This ecological framing – seeing cities and human economies as wholly embedded sub-systems of the biosphere – set the stage for Rees' articulation of the ecological footprint concept. Academic career William E. Rees was initially jointly appointed as Assistant Professor in the University of British Columbia's School of Community and Regional Planning (SCARP) and UBC's Institute for Animal Resource Ecology in September 1969. He was promoted to Associate Professor (1976) and Professor (1990), and became Professor Emeritus following his official retirement from UBC in 2012. Rees taught 15 different courses at UBC from 1969–70 until his retirement in 2011–12. His long-running and interdisciplinary offerings spanned planning practice, environmental assessment, human ecology, and ecological economics. Courses included: Environmental Assessment; Ecological Basis of Planning; Urban Land-use Planning and Economic Change; Resource Analysis for Regional Planning; Enviro-Economic Systems (ecological economics); and Regional Planning Workshop, as well as graduate colloquia including an advanced workshop on Global Change, Complexity, and Panarchy. Rees' research and teaching originally focused on project assessment and the biophysical prerequisites for sustainability in an era of accelerating ecological change. He developed a special interest in cities and in ecologically relevant metrics of urban sustainability, including urban ecological footprint analysis. These pursuits led to explorations of complexity theory, human socio-behavioural ecology, and beyond. As of 2026, Rees remained Professor Emeritus at UBC. His most recent interests and publications explore the role of human evolution in the emergence of the contemporary (un)sustainability crisis. What are the neurobiological, cognitive, and cultural barriers to sustainability? How can we account for humanity's well-developed capacity for self-delusion? Rees has authored or co-authored hundreds of peer-reviewed papers, book chapters, and numerous popular articles on the above and related topics. Active across disciplines, Rees was/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 co-founder of OneEarth Living, a nonprofit "think and do tank" advancing sustainable everyday living around the world. The influence of Rees' work is recognized and awarded . Rees has been invited to lecture on areas of his expertise across Canada and the United States, as well as in Mexico, many European countries, Australia, China, Thailand, Malaysia, Sri Lanka, Indonesia, Japan, South Korea, Brazil, Ecuador, and the former Soviet Union. Within UBC's SCARP, Rees held various senior administrative roles, including Director (1 January 1994 – 30 June 1999). Later, he served as Associate Director of SCARP and the Centre for Human Settlements (2007–2009). Rees also contributed to departmental and university governance. Documented roles include chairing the SCARP Ph.D. Admissions Committee and as a member of UBC's Senior Appointments Committee (2002–2006), and a committee formed to define an undergraduate program in sustainability studies (1998¹–2000).

Ecological footprint

Rees' and his students' work helped establish the ecological footprint, a measure of the human load on Earth, as one of the most widely recognized global sustainability metrics. The term "ecological footprint" is an entry in the Oxford English Dictionary and has become part of the contemporary vernacular. The late biologist and naturalist E. O. Wilson called the ecological footprint "one of the most important environmental concepts today." The Post Carbon Institute describes it as the "world's best-known indicator of the (un)sustainability of techno industrial society." Rees' legacy is closely tied to the ecological footprint concept; the Royal Society of Canada called it his "most influential contribution." Ecological footprint accounting has been acknowledged or used by governments at all levels, by major international organizations and agencies, and by dozens of private consulting firms to assess their or clients' demands on global biocapacity. The Global Footprint Network calls it "the world's premier measure of humanity's demand on nature." American environmentalist and entrepreneur Paul Hawken describes it as "the only standard by which we may calibrate our collective impact upon the planet." The World Wide Fund for Nature (WWF) adopted Ecological Footprint Analysis as a co-indicator of sustainability along with the WWF's own Living Planet Index. In short, the ecological footprint is an unusually successful example of an ecological concept crossing from the academic realm into public and policy language. Rees and other practitioners regret only that the method has not seriously constrained the ethic of perpetual growth.

Ecological economics

Rees has had a significant impact on ecological economics, as ecological footprint accounting is firmly rooted in ecological economic theory. Ecological footprint accounts show graphically that the economy is a growing subsystem within the non-growing biosphere and, while in overshoot, is depleting the finite resources – even essential self-producing resources – of Earth. Rees describes his work on ecological footprint accounting and ecological overshoot as efforts to reconnect humanity functionally to the natural world in ways that reflect better biophysical reality. This perspective distinguishes his work from mainstream economics by insisting that economic systems remain materially constrained by ecosystem dynamics, energy flows, and thermodynamic limits. Neoclassical economists and proponents of ecomodernism, such as the California-based Breakthrough Institute, have pushed back against Rees' theories, arguing that technological innovation and human ingenuity allow economies to decouple from environmental degradation, effectively expanding carrying capacity. In April 2011, Rees was the only ecological economist invited to present that year at George Soros' Institute for New Economic Thinking (INET) Annual Conference at Bretton Woods, a high-level meeting of financiers and finance economists. His renegade paper was titled "Toward a Sustainable Global Economy."

Carrying capacity

Rees' work helped revive the debate about planetary limits and human carrying capacity. He had a major role in elevating discussions around ecological overshoot and the need to constrain consumption and reduce populations. Ecological footprint accounting shows unambiguously how much human demand on ecosystems has outpaced Earth's capacity to regenerate resources and absorb wastes. Swedish scientist Karl-Henrik Robèrt called the method "the most ingenious way of communicating unsustainability to the general public." In short, by explaining sustainability in simple-to-understand terms, Rees has helped elevate the concepts of ecological limits and overshoot to the forefront in sustainability discussions.

Educator

Rees has received praise from former students for his skill in teaching interdisciplinary science, describing his classes as "captivating," "compelling," and "exciting." In a feature on his retirement, the Vancouver-based news site The Tyee quoted former student Thomas Bevan as saying that Rees made the classroom safe for asking "the silliest questions." It corresponds closely to and incorporates all the factors in Paul Ehrlich and John Holdren's widely known definition of human impact on the environment: I = PAT (Impact = Population x Affluence x Technology). A 2023 article by Rees and Wackernagel provides a 30-year update on ecological footprint accounting. Global adoption, policy influence and critiques Ecological Footprint Analysis (EFA) has gained great popular acceptance because it personalizes sustainability by focusing on consumption. It encourages people to reflect on their personal consumption habits and allows nations to estimate their own ecological footprint as well as any "ecological deficit," the difference between domestic biocapacity and a larger ecological footprint. The concept has also seen wide educational integration, with junior and high school textbooks adapting the tool for students. Today the metric is institutionalized and promoted by the Global Footprint Network, which tracks the ecological overshoot of over 200 countries, making it one of the most widely used sustainability indicators in global public policy. Even so, critics argue that Ecological Footprint Analysis is too static. They point out that it relies on agricultural yields per year (ignoring technological improvements in farming) and that it relies heavily on carbon land equivalence while ignoring ocean carbon sinks. Critics often label Rees' predictions of ecological overshoot as "neo-Malthusian" (referencing Thomas Malthus), arguing that his views on population contraction and degrowth are unnecessarily alarmist. Additionally, in public climate discourse, the footprint has been criticized for emphasizing individual responsibility. This is in part because it has been used by the corporate sector in ways perceived to shift responsibility from corporations and governments onto individuals. For example, in 2005, fossil fuel company British Petroleum hired the advertising campaign Ogilvy to popularize the idea of a carbon footprint for individuals. The campaign instructed people to calculate their personal footprints and provided ways for people to "go on a low-carbon diet." This critique has occasionally contributed to broader skepticism toward footprint-based metrics, despite methodological differences between personal carbon footprinting and ecological footprint accounting, which compares demand on ecosystems with biocapacity. In 2002, a Nature news report described skepticism by Danish political scientist Bjørn Lomborg's environmental policy group, including the arguments that there is no single "correct" ecological footprint and that footprint assessments ignored technological developments such as wind and solar electricity. In a published reply, Rees argued that ecological footprint analysis was developed to test claims that the economy was decoupling from nature (it isn't) and disputed the claim that footprint projections ignore renewable energy (RE) growth on grounds that if RE reduced consumption and emissions, the effect would show up in any subsequent eco-footprint study

Awards and honours

Over the course of his career, Rees received a large range of scholarships, fellowships, academic honours, and international awards. These awards showcase his early scholarly achievements and his later contributions to ecological economics and sustainability science. New College In-Course Scholarship, University of Toronto (1965–1966) National Research Council of Canada Postgraduate Scholarship (1966–1967) Ramsay Wright Scholarship, Department of Zoology, University of Toronto (1967–1968) National Research Council of Canada Postgraduate Scholarship (1967–1968) National Research Council of Canada Postgraduate Scholarship (1968–1969) Social Sciences and Humanities Research Council Study Leave Fellowship and Grant (1985–1986) Killam Senior Research Prize, University of British Columbia (1996) Named one of British Columbia's top / leading public intellectuals by the Vancouver Sun (2000) City of Barcelona 2004 Award (Multimedia Category), as a member of the winning team for the exhibition Inhabiting the World (awarded 10 February 2005) Elected Fellow of the Royal Society of Canada (FRSC) (2006) Pierre Elliott Trudeau Foundation Fellowship (2007–2010) Honorary Doctoral Degree, Laval University (2012) Kenneth Boulding Prize / Boulding Memorial Award in Ecological Economics (jointly with Mathis Wackernagel) (2012) Blue Planet Prize (jointly with Mathis Wackernagel) (2012) Herman Daly Award in Ecological Economics (2015) Dean's Medal of Distinction, UBC Faculty of Applied Science (2016)

References

Representative publications

William E. Rees has written extensively across academic, policy, and public platforms. Biographies and source materials consistently describe him as the author or co-author of hundreds of peer-reviewed papers, book chapters, and popular articles. In addition to academic papers, popular articles, and public presentations on ecological footprinting, ecological economics, sustainability, ecological overshoot, and the human ecological predicament, Rees' recent writing continues in a reflective public form through his "standstoreeson" platform on the online Substack application. These are some of Rees' scholarly articles and popular publications: Rees, W.E. and K. Szocik. 2026. Overshoot and procreative ethics: at an ecological crossroads. Sustainability Science. https://doi.org/10.1007/s11625-026-01810-2 Rees, W.E. 2026. Reframing the SDGs: Can they be tethered to reality? In N. Montesano Montessori and A.K. Lautensach (eds.). The Palgrave Handbook of Critical Approaches to the UN 2030 Sustainable Development Goals. Palgrave Macmillan. (in press) Rees, W.E., D. Appleby, A. Yamabe, V. Timmer, and D. Timmer. 2026. One-earth living explained. In M.J. Cohen, S. McGreevy, S. Lorek, R. Lambino, and M. Bengtsson (eds.). Handbook of Research on Sustainable Lifestyles. Cheltenham, UK. Edward Elgar Publishing. Rees, W.E. 2025. Energy overshoot. In L. Akenji, P.J. Vergragt, H. S. Brown, T.S.J. Smith, and L.M. Wallnöfer (eds.). Vocabulary for Sustainable Consumption and Lifestyles. Sustainable Consumption Research and Action Initiative. London, Routledge. https://doi.org/10.4324/9781003584056 Rees, W.E. 2024. On being a snowflake in an avalanche: The catastrophe of overshoot and how to cope. Resilience 11 July 2024. https://www.resilience.org/stories/2024-07-11/on-being-a-snowflake-in-an-avalanche-the-catastrophe-of-overshoot-and-how-to-cope Rees, W.E. 2023. The human ecology of overshoot: Why a major 'population correction' is inevitable. World 4: 509–27. https://doi.org/10.3390/world4030032 Rees, W.E. 2023. The human eco-predicament: Overshoot and the population conundrum. Vienna Yearbook of Population Research 21(1): 21–39. Vienna Institute of Demography of the Austrian Academy of Sciences. Vienna. Rees, W.E. and M. Wackernagel. 2023. Ecological Footprint Accounting: Thirty years and still gathering steam. Environment: Science and Policy for Sustainable Development 65(5): 5–18. https://doi.org/10.1080/00139157.2023.2225405 Rees, W.E. 2022. Why Large Cities Won't Survive the Twenty-First Century. In R.C. Brears (ed.). The Palgrave Encyclopedia of Urban and Regional Futures. Palgrave Macmillan, Cham. https://doi.org/10.1007/978-3-030-87745-3_285 Rees, W.E. 2020. The fractal biology of plague and the future of civilization. The Journal of Population and Sustainability 5(1): 15–30. https://www.whp-journals.co.uk/JPS/article/view/653/408 Rees, W.E. 1996. Revisiting carrying capacity: Area-based indicators of sustainability. Population and Environment. 17(3): 195–215. https://doi.org/10.1007/BF02208489 Merz, J.J., Barnard, P., Rees, W.E., Smith, D., Maroni, M., Rhodes, C.J., Dederer, J.H., Bajaj, N., Joy, M.K., Wiedmann, T., Sutherland, R. 2023. "World scientists' warning: the behavioural crisis driving ecological overshoot." Science Progress. 106: https://doi.org/10.1177/00368504231201372. Barnard, P., Moomaw, W.R., Fioramonti, L., Laurance, W.F., Mahmoud, M.I., O'Sullivan, J., Rapley, C.G., Rees, W.E., Rhodes, C.J., Ripple, W.R., Semiletov, I.P., Talberth, J., Tucker, C., Wysham, D., Ziervogel, G. 2021. "World scientists' warnings into action: local to global." Science Progress. 104: https://doi.org/10.1177/00368504211056290 Rees, W.E. 2020 "MegaCities at Risk: The Climate–Energy Conundrum", chapter in: Sorensen, A and Labbe, D (eds.) The International Handbook on Megacities and Megacity Regions. Cheltenham: Edward Elgar. Rees, W.E. 2020. "Scorched Earth", foreword to H. Washington, What Can I do to Help Heal the Environmental Crisis, London: Earthscan (Routledge), p. xxii-xxvi. Rees, W.E. 2019. "Avoiding the 'Endarkenment'", foreword to J Bell and J Marlow, Sketches of the History of Science, Montreal: Champlain St-Lambert, p. ix –xi. Rees, W.E. 2019 "End Game – The economy as eco-catastrophe and what needs to change". Real-World Economics Review ( March 2019) at http://www.paecon.net/PAEReview/issue87/Rees87.pdf Rees, W.E. 2018. "Planning in the Anthropocene", Chapter 5 in: M Gunder, A Madinipour and V Watson (eds), The Routledge Handbook of Planning Theory. New York: Routledge. Rees, W.E. 2017. "Going Down? Human Nature, Growth and (Un)sustainability," Chapter 22 in: PA Victor, B Dolter (eds), Handbook on Growth and Sustainability. Cheltenham, UK: Edward Elgar. Rees, W.E. 2013. "Ecological Footprint, Concept of." In: Levin S.A. (ed.) Encyclopedia of Biodiversity, second edition, Vol. 2: 701–713. Waltham, MA: Academic Press. Rees, W.E. 2010. "True Cost Economics". Chapter in the Berkshire Encyclopedia of Sustainability, Vol 2, The Business of Sustainability. C. Lazlo et al. eds. Berkshire Publishing Group. Rees, W.E. 2010 "The Roots of Our Crises: Does Human Nature Drive Us Toward Collapse?" Chapter 6 in: D Lerch (ed), The Community Resilience Reader. Washington, Island Press (for the Post Carbon Institute.) Rees, W.E. 2006. "Ecological Footprints and Bio-Capacity: Essential Elements in Sustainability Assessment." Chapter 9 in Jo Dewulf and Herman Van Langenhove (eds) Renewables-Based Technology: Sustainability Assessment, pp. 143–158. Chichester, UK: John Wiley and Sons. Rees, W.E. 2006. "Why Conventional Economic Logic Won't Protect Biodiversity." Chapter 14 in D.M. Lavigne (ed.). Gaining Ground: In Pursuit of Ecological Sustainability, pp. 207–226. International Fund for Animal Welfare, Guelph, Canada, and the University of Limerick, Limerick, Ireland. Rees, W.E. 2004." Is Humanity Fatally Successful?" Journal of Business Administration and Policy Analysis 30-31: 67-100 (2002–2003). Rees, W.E. 2003. "Understanding Urban Ecosystems: An Ecological Economics Perspective." Chapter in Alan Berkowitz et al.eds., Understanding Urban Ecosystems. New York: Springer-Verlag. Rees, W.E. 2002. "Globalization and Sustainability: Conflict or Convergence?" Bulletin of Science, Technology and Society 22 (4): 249–268. Moore, J and W.E. Rees. 2013. "Getting to One Planet Living". Chapter 4 in: State of the World 2013 – Is Sustainability Still Possible? Washington, World Watch Institute. Kissinger, M. & W.E. Rees. 2010. "An interregional ecological approach for modelling sustainability in a globalizing world—Reviewing existing approaches and emerging directions." Ecological Modelling 221(21):2615-2623. Kissinger, M & W.E. Rees. 2010. "Importing terrestrial biocapacity: The U.S. case and global implications." Land Use Policy 27: 589–599. Kissinger, M & W.E. Rees. 2009. "Footprints on the Prairies: Degradation and Sustainability of Canadian Agriculture in a Globalizing world." Ecological Economics 68: 2309–2315 Wackernagel, M. and W. Rees. 1996. Our Ecological Footprint: Reducing Human Impact on the Earth. New Society Publishers.

External links

Video of talk for the World Federalist Movement Vancouver, Canada; April 2010 Post Carbon Institute The Great Simplification podcast (Jan 2023): William E. Rees: "The Fundamental Issue – Overshoot"

Text derived from https://en.wikipedia.org/w/index.php?oldid=1377218755 under CC BY-SA 4.0; modifications have been made.