The Hot Zone

Population growth could reverse carbon reduction gains

Posted by Alison Hawkes on October 15, 2010
Category : Climate Science and Scientists, The man made climate

Back in the late 1960s, the environmental movement was in a tizzy over predictions that overpopulation would soon cause mass human starvation and eventually kill the planet. But the Malthusian vision fell to the wayside once the Green Revolution made farming that much more productive and countries began enacting environmental reforms that lessened some of the worst abuses in pollution.

These days you don’t hear much concern over the size of Earth’s ballooning human population, even as it reaches nearly 7 billion people — nearly twice the population of 1970.

Yet the topic has popped up again, this time in the context of climate change. In a paper to be published in the Proceedings of the National Academy of Sciences, researchers led by the National Center for Atmospheric Research found that adding another three billion people by mid-century (considered a conservative population estimate)  could reverse many of the gains won in greenhouse gas emissions reductions.

A 16 to 29 percent reduction in emissions — deemed necessary to stem the serious consequences of rising global temperatures — would be offset by the additional carbon produced by the extra people.

Of course, the problem would be helped by lowering the world’s birth rate.

“A slowing of population growth in developing countries today will have a large impact on future global population size. However, slower population growth in developed countries will matter to emissions, too, because of higher per capita energy use,” said Shonali Pachauri, a researcher at the International Institute for Applied Systems Analysis in a UCAR press release.

The researchers went on to analyze which subsets of the population would add the most emissions. Surprisingly to smart growth advocates, a growth in the urban population could lead to a 25 percent rise in emissions in some developing countries — particularly China and India –  because city living tends to lead to economic growth and higher rates of consumption. An aging population reduces emissions because of lower productivity.

Population growth is a condition not typically considered in climate scenarios, but arguably should be, since it’s surely not going to remain stagnant. Check out this video of Brian O’Neill from NCAR for more info:

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