Prof. Rees is well-known for inventing the "ecological footprint analysis" - photo by Perry Zavits / Klixpix

UBC Reports | Vol. 52 | No. 4 | Apr. 6, 2006

Footprints to Sustainability

By William E. Rees Professor
School of Community and Regional Planning

Almost everyone knows Pogo ‘Possum’s famous utterance from Earth Day, 1970. On contemplating the desecration of his beloved Okefenokee Swamp, Walt Kelly’s memorable cartoon-strip character sadly observed: “We have met the enemy and he is us.”

Well, 36 years later, the rest of us are just catching up with Pogo in appreciating the meaning of ecological degradation. It is finally penetrating our consciousness that climate change, tropical deforestation, desertification, the ozone hole, fisheries collapses -- the whole litany of so-called environmental problems -- aren’t really “environmental” problems at all. They are actually the raw symptoms of human ecological dysfunction. We have indeed met the enemy and he is us.

One way of determining how great an enemy we are, is through ecological footprint analysis (EFA). I began developing this method over two decades ago after finding myself embroiled in a debate with an economist colleague over the relevance of ecological carrying capacity to humans. He argued the conventional wisdom of the day, that the combination of trade and human technological ingenuity enables modern humans to squeeze so much out of the earth that the term “human carrying capacity” is now meaningless.

Lawrence Summers, then Chief Economist of World Bank, put it this way in 1991: “There are no... limits to the carrying capacity of the earth that are likely to bind any time in the foreseeable future. There isn’t a risk of an apocalypse due to global warming or anything else. The idea that we should put limits on growth because of some natural limit, is a profound error and one that, were it ever to prove influential, would have staggering social costs.”

Back then, such assertions were made with intimidating assurance and conviction, but to my ecologist’s ears something was missing from the implied cornucopian vision. In part, the problem lay with the standard definition of carrying capacity. To ecologists and game managers, carrying capacity is the maximum population of a given species that can occupy a particular habitat without impairing its long-term productivity. However, if humans are the species, and trade and technology augment local productivity, well… maybe the economists have a point.

But what happens if we invert the carrying capacity ratio? Rather than asking what population a given area can support, let’s ask how much area is needed to support a given population, wherever the area is or however technologically sophisticated the population. This shift in perspective merely acknowledges that trade and technology don’t actually decouple economies from nature, they merely shuffle resources around and increase the intensity of resource exploitation. It thus re-establishes humans’ direct connection to the land and puts global carrying capacity firmly back on the sustainability agenda.

Eco-footprinting thus starts from a series of simple premises:

• People remain integral components of the ecosystems that sustain them;
• Most human impacts on ecosystems are associated with energy and material extraction and consumption (all economic activity has material consequences);
• Many energy and material flows are readily measurable and can be converted to corresponding productive or assimilative ecosystems areas;
• There is a finite area of productive land and water ecosystems on Earth.

From this perspective, every human population imposes an ecological ‘load’ or ‘footprint’ on Earth measured in terms of sustained demand for bio-productivity. We therefore define the ecological footprint of a specified population as the area of land and water ecosystems required, on a continuous basis, to produce the resources that the population consumes, and to assimilate (some of) the wastes that the population produces, wherever on Earth the relevant land/water is located. Per capita eco-footprints can be estimated by dividing aggregate national footprint by the total population.

What does EFA tell us that might be relevant to prospects for global sustainability? For starters:

• Energy / material consumption remains highly correlated with rising GDP/income per capita;
• The average eco-footprints of high-income countries range from about 4.5 to almost ten hectares of global average productivity per capita (ha/cap); those of developing countries are as small as 0.5 ha/cap;
• Many high-income countries have eco-footprints up to several times the size of their domestic bio-capacities;
• The average human eco-footprint is about 2.2 ha/cap;
• There are only about 1.8 ha/cap significantly productive land and water on Earth.

These five key findings alone suggest that the sustainability challenge is greater than the world community has heretofore been willing to concede. First, the denizens of wealthy market economies like the US, Canada, most Western European countries and Japan appropriate two to five times their equitable share of earth’s bio-capacity while those of low-income countries like Bangladesh, Mozambique and even China, use only a fraction of their equitable allocation.

Second, many wealthy consumer societies have greatly overshot their domestic carrying capacities and are running large eco-deficits with the rest of the world. These countries would have long since stabilized or imploded in the absence of trade. As expected, trade sustains short-term growth and short-circuits the negative feedback from degraded ecosystems that would otherwise serve to warn countries that they are approaching local biophysical limits. In effect, the world’s rich nations finance their ecological deficits by extending their ecological footprints deeply into exporting nations and the open ecosphere. (We now achieve through commerce what used to require territorial occupation!) The downside is that by shuffling bio-capacity around, trade ensures that the entire human family will hit global limits simultaneously.

Third is an obvious ecological corollary - not all countries can run an eco-deficit. For every sustainable deficit there must be a permanent surplus somewhere else and there are no true surpluses. The aggregate world population has already overshot global carrying capacity by about 20 per cent (The direct empirical evidence is accelerating global degradation).

Fourth, on an ecologically full planet, the less-developed countries cannot sustainably follow the developed world’s path to material extravagance. If 1.2 billion people of China had the same per capita eco-footprint as citizens of the US, China alone would require the entire bio-capacity of Earth. (The US, with less that 5 per cent of the world’s population, uses about a quarter of its resources.) To bring the present world
population up to, say, North American material standards with prevailing technology would require four additional Earth-like planets! This poses a conundrum for growth-based sustainability. As someone once wryly observed, “good planets are hard to find.” An ever-expanding global economy thus puts humanity on a collision course with ecological sustainability. Geo-political sustainability too - in a competitive world of climate change and increasing resource shortages, rising material expectations everywhere may become greatest threat to human security.

The challenge of EFA to sustainability is therefore really quite straightforward. We must learn to share Earth’s bio-capacity more equitably. First-World countries should be implementing policy measures to reduce their per capita ecological footprints to 1.8 ha/capita to create the ecological space for needed growth in the Third World - and the reductions will have to deepen as world population grows. For wealthy consumer societies, this implies a 75 per cent reduction in material and energy consumption and poses an immense challenge both to technology and lifestyles. (Other energy / material flows studies argue for 90 per cent reductions). These numbers may seem politically impossible, but they are ecologically necessary for sustainability. Unfortunately, prevailing mainstream approaches merely makes the growing human enterprise more efficiently unsustainable.