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How Many People Can the Earth Support?

February 15, 2010

The answer you will get from Joel Cohen’s very good book of the same title is: Well, that depends! It depends on who they are, where they are, what they are doing, what they want, and countless other factors. Cohen demonstrates that attempts to reduce any population-related problem into a simple question of numbers lead us astray.

James Arvanitakis, writing at, explains why a focus on the raw numbers of population growth is not going to help advance policy debates about climate change and other environmental issues. He points to an important point made by George Monbiot:

those worrying most about population seem to be post-reproductive middle aged, comfortable white men who have reached a certain level of material success. Further, Monbiot reminds us, the population explosion is the one environmental problem that this high energy consuming sub-section of the population can not actually be blamed for.

Both Monbiot and Arvanitakis argue that it’s not about how many people, but how much consumption. Limiting population growth implies over-simplistic, potentially draconian policy measures that conflict with closely-held values associated with personal freedoms and human dignity. What’s more, focusing the discussion on limiting further growth is essentially an argument that privileged people shouldn’t have to change.

Population and GDP of Australia: 1970-2008

I agree that the population debate is over-simplistic (and sometimes morally troubling), but also feel that a single-minded focus on consumption is similarly naive: people are not going to give up what they have (for example, see this piece on Jared Diamond). It is inappropriate for a country to expect a policy of exclusion to be viable on the long term. But it’s also inappropriate to just ignore population issues entirely.

Overly simplistic policies focused on near term reductions in consumption OR population growth are likely to fail. Each requires a long term strategy acknowledging the slow pace of various forms of change. What’s more, successful policy interventions may not be direct.

For example, China’s simple, direct one-child-per family policy led to a gender imbalance with a variety of cascading, destabilizing effects. Yet we know that education and empowerment of women are strongly associated with lower population growth. The best way to limit population growth on the long term may be through indirect policies aimed at education and human rights.

Another example is greenhouse gases. Attempts to limit these gases directly fall prey to political realities: people do not want to give up what they have. This explains the weakness of cap and trade schemes currently under consideration by various governments. We know that until low-carbon technologies can compete with carbon-intensive technologies, this will continue to be a problem. So the best way to limit emissions in the future may be through indirect policies focused on technology research and development.

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