Equal per capita CO2 emissions vs global population growth

George Monbiot’s book about climate change, Heat, recommends a scheme of global emission reductions based on the principle of equity. That is, every person on the planet should have an equal right to emit a certain amount of CO2 per year, with some long-term total emissions cap that keeps the planet from getting too hot. I have seen a number of other commentators invoke this principle, too.

The principle of equity means that the “rich” (heavy users of CO2) would have to pay the “poor” (who emit less than a sustainable level) to maintain their lifestyles, an equalizing force in an increasingly unequal world. And it would preserve some room for the poorest countries to develop their economies, while making the advanced countries (who have already developed on the basis of extensive CO2 emissions) bear more of the burden of adjustment.

But while this logic is impeccable, I detect a rather large fly in the ointment, and that is global population increases. If you believe the projections, global population could hit 9-10 billion by mid-decade, up from about 6.5 billion today. So an additional 3 billion people who would represent a net increase in global population, by 2050 would command about one-third of global CO2 emissions.

I’ve never been one to be excessively concerned about global population, given that the resource demands in parts of the world where the increase is happening tend to be on the low side. Yet, if we take equal per capita CO2 emissions seriously, we now have a problem. If we are going down that road, we need to simultaneously be talking about targets for global population, so that we peak at a much lower number (and how and whether this could be practically implemented is a huge question).

Alternatively, we abandon equity and do not consider population growth. Or it could also be the case that climate change itself, due to droughts, extreme weather and so forth, will act to limit global population growth. But the numbers are pretty grim, in terms of total per person reductions, if we have both equity in per capita emissions AND accept population growth on that scale.

This issue is a global version of the intensity targets issue, raised in areas such as transportation. All well and good to reduce emissions per car, but if we ignore the increasing total amount of cars on the road, we cannot reduce total emissions.

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