Consumption dwarfs population as main environmental threat

Look at it another way. Just five countries are likely to produce most of the world’s population growth in the coming decades: India, China, Pakistan, Nigeria, and Ethiopia. The carbon emissions of one American today are equivalent to those of around four Chinese, 20 Indians, 30 Pakistanis, 40 Nigerians, or 250 Ethiopians.

Even if we could today achieve zero population growth, that would barely touch the climate problem - where we need to cut emissions by 50 to 80 per cent by mid-century. Given existing income inequalities, it is inescapable that overconsumption by the rich few is the key problem, rather than overpopulation of the poor many.

But, you ask, what about future generations? All those big families in Africa begetting yet-bigger families. They may not consume much today, but they soon will.

Well, first let’s be clear about the scale of the difference involved. A woman in rural Ethiopia can have ten children and her family will still do less damage, and consume fewer resources, than the family of the average soccer mom in Minnesota or Munich. In the unlikely event that her ten children live to adulthood and have ten children of their own, the entire clan of more than a hundred will still be emitting less carbon dioxide than you or I.

And second, it won’t happen. Wherever most kids survive to adulthood, women stop having so many. That is the main reason why the number of children born to an average woman around the world has been in decline for half a century now. After peaking at between 5 and 6 per woman, it is now down to 2.6.

This is getting close to the “replacement fertility level” which, after allowing for a natural excess of boys born and women who don’t reach adulthood, is about 2.3. The UN expects global fertility to fall to 1.85 children per woman by mid-century. While a demographic “bulge” of women of child-bearing age keeps the world’s population rising for now, continuing declines in fertility will cause the world’s population to stabilise by mid-century and then probably to begin falling.

Far from ballooning, each generation will be smaller than the last. So the ecological footprint of future generations could diminish. That means we can have a shot at estimating the long-term impact of children from different countries down the generations.

The best analysis of this phenomenon I have seen is by Paul Murtaugh, a statistician at Oregon State University. He recently calculated the climatic “intergenerational legacy” of today’s children. He assumed current per-capita emissions and UN fertility projections. He found that an extra child in the United States today will, down the generations, produce an eventual carbon footprint seven times that of an extra Chinese child, 46 times that of a Pakistan child, 55 times that of an Indian child, and 86 times that of a Nigerian child.

Of course those assumptions may not pan out. I have some confidence in the population projections, but per-capita emissions of carbon dioxide will likely rise in poor countries for some time yet, even in optimistic scenarios. But that is an issue of consumption, not population.

In any event, it strikes me as the height of hubris to downgrade the culpability of the rich world’s environmental footprint because generations of poor people not yet born might one day get to be as rich and destructive as us. Overpopulation is not driving environmental destruction at the global level; overconsumption is. Every time we talk about too many babies in Africa or India, we are denying that simple fact.

At root this is an ethical issue. Back in 1974, the famous environmental scientist Garret Hardin proposed something he called “lifeboat ethics”. In the modern, resource-constrained world, he said, “each rich nation can be seen as a lifeboat full of comparatively rich people. In the ocean outside each lifeboat swim the poor of the world, who would like to get in.” But there were, he said, not enough places to go around. If any were let on board, there would be chaos and all would drown. The people in the lifeboat had a duty to their species to be selfish - to keep the poor out.

Hardin’s metaphor had a certain ruthless logic. What he omitted to mention was that each of the people in the lifeboat was occupying ten places, whereas the people in the water only wanted one each. I think that changes the argument somewhat.