by Zoë Pollock

 Robert Kunzig considers a growing global population, projected for 9 billion by 2045:

Before the 20th century, no human had lived through a doubling of the human population, but there are people alive today who have seen it triple. Sometime in late 2011, according to the UN Population Division, there will be seven billion of us. ...

Carbon emissions from fossil fuels are growing fastest in China, thanks to its prolonged economic boom, but fertility there is already below replacement; not much more can be done to control population. Where population is growing fastest, in sub-Saharan Africa, emissions per person are only a few percent of what they are in the U.S.so population control would have little effect on climate. Brian O’Neill of the National Center for Atmospheric Research has calculated that if the population were to reach 7.4 billion in 2050 instead of 8.9 billion, it would reduce emissions by 15 percent. “Those who say the whole problem is population are wrong,” Joel Cohen says. “It’s not even the dominant factor.” To stop global warming we’ll have to switch from fossil fuels to alternative energyregardless of how big the population gets. The number of people does matter, of course. But how people consume resources matters a lot more.

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