Population Institute of Canada

William Catton Jr. explained the condition of overshoot in his insightful book, Overshoot: The Ecological Basis of Revolutionary Change.^ⁱ Catton defines overshoot as follows: “(verb) to increase in numbers so much that the habitat’s carrying capacity is exceeded by the ecological load, which must in time decrease accordingly; (noun.) the condition of having exceeded for the time being the permanent carrying capacity of the habitat.”^ⁱⁱ

In the past 10,000 years the human population has increased from 5-10 million to about 6.5 billion in 2005. At first, this growth was sustained by displacing other species from land areas, but in the past two hundred years, humanity has expanded enormously based on a much more precarious practice of rapidly drawing down finite natural resources, many of which are becoming scarce. The transition from living sustainably on the Earth to drawdown can happen seamlessly. Overshoot can even generate a surge of wealth, for example, as occurred with the discovery of oil in many parts of the world, and the resultant prosperity in the short-term reinforces the belief that this is the proper way to proceed over the longer-term. This is the illusion that currently bewitches the mass of humanity with the dream of easy money. Paved with such deception, this road leads inevitably to collapse and die-off.

Is Humanity in a State of Overshoot on Earth?

Evidence suggests that humanity is now in a state of overshoot, and this situation is rapidly worsening with the exponential growth of human numbers, demands, and the power of human technologies. In the perspective of Catton, the industrial revolution is the prelude to collapse. Wielding powerful tools, homo sapiens has become homo colossus while remaining predominantly indifferent to the environmental consequences of collective human actions. It is a tragedy with humanity playing the role of tragic hero, conscious but perhaps not conscious enough to prevent a catastrophic ending.

In 1972, The Club of Rome brought the potential for overshoot to global attention very effectively at a time when preventive steps might have avoided it. The book, Limits to Growth, warned of the shortages of key natural resources that were likely to occur in the twenty-first century given the projection of trends then in place. Beyond the Limits, published in 1992, emphasized that humans had already overshot the limits of the support capacity of the Earth. In Limits to Growth: The 30-Year Update^ⁱⁱⁱ, published in 2004, the authors noted that human demands exceed the long-term productivity of the living Earth by about twenty percent.

These concerns are shared by The Union of Concerned Scientists, who, in November, 1992, delivered the World Scientists' Warning to Humanity, in which 1,700 of the world's leading scientists, including the majority of Nobel laureates in the sciences, warned:

“Human beings and the natural world are on a collision course. Human activities inflict harsh and often irreversible damage on the environment and on critical resources. If not checked, many of our current practices put at serious risk the future that we wish for human society and the plant and animal kingdoms, and may so alter the living world that it will be unable to sustain life in the manner that we know. Fundamental changes are urgent if we are to avoid the collision our present course will bring about.

In March 20, 2006, with the release of its report, Global Biodiversity Outlook 2, the UN Environment Programme delivered a similar message. The Report warns that humans have provoked the worst spate of extinctions since the dinosaurs were wiped out sixty-five million years ago. It emphasizes that we humans are currently responsible for the sixth major extinction event in the history of Earth. A rising human population of six and a half billion is destroying the environment for thousands of other species with the global demand for biological resources now exceeding the planet's capacity to renew them by twenty percent. The reference here is to biological resources but just as serious for the human future is the rapid drawdown of non-renewable resources such as fossil fuels and base metals.

The following facts support the position that we are, in fact, in overshoot:

World fish stocks are down by an astonishing ninety percent since the dawn of modern industrialized fishing about 1950. Some desperate fishers have taken to bombing coral reefs, turning them into underwater deserts.

A third of all amphibians, over a fifth of mammals, and a quarter of coniferous trees, are threatened with extinction.
Human activity has caused between fifty and a thousand times more extinctions in the last one hundred years than would have happened due to natural processes.
Sixty percent of the services provided by the world’s ecosystems that support human well-being are either degraded or heading that way.
The fastest deterioration of ecosystems is occurring in developing countries where population is growing the fastest.
Forty percent of agricultural land has been degraded during the past century.
The UN World Water Development Report (2003) projects that, at worst, as many as seven billion people in sixty countries could face water scarcity by 2050. Even under the most favorable projection for water, an estimated two billion people in sixty countries will live water-scarce lives by 2050. Meanwhile, humans are drawing down underground aquifers and polluting fresh and marine waters at an accelerating rate.
There is increasing agreement that peak oil, the point at which the global production of petroleum will begin to decline, has already occurred or is near.
Inexpensive oil is the foundation of modern industrial civilization and declining supplies will have a devastating effect on most aspects of human life:
- Ninety percent of transportation is fuelled by oil.
- Oil is essential for construction, consumer products, heating, manufacturing, and electronics.
- It is critical for all aspects of modern agriculture: fertilizers, farm machinery, pesticides, refrigeration, and transportation. It has been estimated that our food in Canada travels an average of 2080 kilometres from farm to plate.
It is very likely that peak oil marks the end of the growth phase of global industrial society. This a natural part of the cycle of any dynamic system. The initial growth phase is followed by decline when the higher grade resources become depleted.

The following comment taken from the Millennium Ecosystem Study sums up current conditions:

“The changes made to ecosystems have contributed to substantial gains in human well-being and economic development, but these gains have been achieved at growing costs. These costs include the degradation of many ecosystem services, increased risk of abrupt changes, and increased poverty for some groups of people. These problems, unless addressed, will substantially reduce the benefits that future generations get from ecosystems.”

Our collective response to these warnings has been to press on the accelerator instead of the brakes. With globalization in full swing, resource hungry corporations, hyperactive consumers and restless migrants threaten to pick the planet clean. However, the convergence of a growing list of serious problems reminds humanity of the risk of overshoot. The risks are so overwhelming one is left in astonishment that humanity has not responded with a profound shift towards sustainability in our relationship with the rest of life.

Evidence suggests that we humans are well into overshoot and that our population and civilization may be much closer to collapse than we care to admit.