Limits to growth – 2002 predictions and evidence since

I am reading the 2002 update to Limits to Growth (, a book originally published in 1972. The book describes models run to simulate how the planet, ecosystem and economy will react to the collision between exponential growth and finite physical resources. As you can imagine, it was not popular at the time, and you could make a cogent argument that the popular debate has hardly advanced since.

Which is depressing, because many of their original predictions have proved startlingly accurate (see for example But then why have vested interests ever let facts, evidence and testable predictions get in the way of defence of a (profitable) status quo? Tobacco industry anyone?

The fundamental property that the dynamical systems model (theirs is called “World3”) highlights is that any system with growth, finite resources and delays in reactions, is prone to Overshoot. This is like driving at a set of traffic lights that turns red: if you’re travelling slow enough and your reaction time and brakes are good enough, you will stop in time; if you’re travelling too fast, your reaction time is slow or your brakes inadequate, the inevitable result is Overshoot. This applies to industrial output, food production, pollution levels etc.

In the 2002 update, the authors give a list of symptoms that would indicate that the global system was heading for an Overshoot (and, for the avoidance of doubt, that is not a clever place to be). What struck me was the mountain of evidence against many of these that has arisen since 2002. I thought I would give the list in full, together with examples of evidence that has arisen since the work was published. This last point is important, because rear view mirror science is no good: a prediction must be made before you know the evidence and the evidence gathered afterwards.

The excerpt from the book begins with a couple of introductory paragraphs, followed by the indicators, with the evidence in italics for each point.

“Any population–economy–environment system that has feedback delays and slow physical responses; that has thresholds and erosive mechanisms; and that grows rapidly is literally unmanageable. No matter how fabulous its technologies, no matter how efficient its economy, no matter how wise its leaders, it can’t steer itself away from hazards. If it constantly tries to accelerate, it will overshoot. By definition, overshoot is a condition in which the delayed signals from the environment are not yet strong enough to force an end to growth.

How, then, can society tell if it is in overshoot? Falling resource stocks and rising pollution levels are the first clues. Here are some other symptoms:

• Capital, resources, and labor diverted to activities compensating for the loss of services that were formerly provided without cost by nature (for example, sewage treatment, air purification, water purification, flood control, pest control, restoration of soil nutrients, pollination, or the preservation of species). Record investment needed in the water industry globally ( ; Record amount spent on flood defence infrastructure and flood insurance (

• Capital, resources, and labor diverted from final goods production to exploitation of scarcer, more distant, deeper, or more dilute resources. Tar sands anyone?

• Technologies invented to make use of lower-quality, smaller, more dispersed, less valuable resources, because the higher-value ones are gone. Fracking? Many primary mine tailings are now being mined for their residual resources (e.g. Cobalt)

• Failing natural pollution cleanup mechanisms; rising levels of pollution. CO2… see e.g.

• Capital depreciation exceeding investment, and maintenance deferred, so there is deterioration in capital stocks, especially long-lived infrastructure.

• Growing demands for capital, resources, and labor used by the military or industry to gain access to, secure, and defend resources that are increasingly concentrated in fewer, more remote, or increasingly hostile regions. Iraq? China in Africa?

• Investment in human resources (education, health care, shelter) postponed in order to meet immediate consumption, investment, or security needs, or to pay debts. Euro crisis? US deficit?

• Debts a rising percentage of annual real output. No need to point out evidence of this one…

• Eroding goals for health and environment.

• Increasing conflicts, especially conflicts over sources or sinks. Water conflicts in Africa; fortunately this hasn’t erupted yet, but did bread prices pay a part in the Arab spring?

• Shifting consumption patterns as the population can no longer pay the price of what it really wants and, instead, purchases what it can afford. Downtrading in retail post financial crisis?

• Declining respect for the instruments of collective government as they are used increasingly by the elites to preserve or increase their share of a declining resource base. Occupy Wall Street? Arab Spring?

• Growing chaos in natural systems, with “natural” disasters more frequent and more severe because of less resilience in the environmental system. Hurricane Katrina, Arctic Ice Extent collapse, Heat records all over the world, Asian floods. Do I need to go on.

For me the message of all this is that we all need to collectively wake up and smell the coffee. We could screw this planet up in the next decade if we don’t change course very quickly. I work every day with companies who try in some small way to address these challenges, and am well aware that these tiny actions make little to no difference on a global scale. But if many people pull in the same direction, we can turn the boat round and set sail on a sustainable course.

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