Will Slower Population Growth Stop Global Warming?

To the Editors:

Once again a highly informative, well-written, and lively article by Bill McKibben on books with an environmental theme [“Can Anyone Stop It?,” NYR, October 11]. Even enjoyable, notwithstanding the frightening prospects in store for the planet, even in some of the better scenarios. But it seems a crucial element has been largely overlooked in the review (not the fault of McKibben, I am sure), as in most of the recent public discussion of global warming and the growing scarcity of natural resources: population.

In the early 1970s, toward the beginning of the modern environmentalist movement, one often heard about ZPG, zero population growth, or (more ambitious yet) NPG, negative population growth. At the time there were, I think, barely four billion people on the planet, at a level of resource consumption considerably lower than today’s. I recall thinking then, bad enough already the environmental impact of the developed world; how much worse will it be when the average Indian or Chinese also has an automobile, a refrigerator, and air-conditioning? (Nothing against the Indians and the Chinese as such, of course.)

I don’t know where the political will might ever be found, in any country, to suppress unrestrained consumption. By themselves, higher prices for energy (and water, and food) won’t do it, I’m afraid. I see little inclination, even on the part of environmentally enlightened people, to make any lifestyle choices that would entail personal sacrifice or any significant reduction in living standard (as measured by resource consumption). We’ll heat the house a bit less and wear sweaters indoors in winter. We’ll buy smaller cars. Seems we’re all betting on technology and public policy to save our planetary butt. But is this such a good bet? Should we feel optimistic, given the worldwide political climate today?

Prudent gamblers and investors all know about hedging. Any attempt to curtail global warming or to provide renewable resources (and to make the nonrenewable ones last a little longer) will be at a grave disadvantage without a serious initiative to bring population growth under control—or even reduce it over the decades to come. Population acts (I suppose) pretty much as a simple multiplier in this massive and otherwise complex calculation whose product may well be a multifaceted global calamity (which would be a very unpleasant way to correct our overpopulation). All other factors being whatever they will be, we can only gain by having n billions of people instead of 1.2n or 1.5n or 2n. Is this really a hotter potato than the one that would ask us to give up our cars? Bill, why aren’t we all talking more about this?

Allen Schill

Turin, Italy

Bill McKibben replies:

Many thanks to Mr. Schill for his letter. It raises a common and important point, and one I have tried to address in the past (see my book Maybe One). In general terms, population is one of the few major environmental trends heading in the right direction. Partly as a result of the Earth Day–era alarms that Mr. Schill describes, people in this country and then, more importantly, in the developing world itself began searching for ways to slow population growth, which was foreseen to involve an almost infinite series of doublings. The best contraceptive turned out to be education and, to one degree or another, giving women more control of their lives (though a supply of actual contraceptives was also necessary).

Despite, in recent times, ham-handed efforts by American administrations to interfere, those efforts have met with measurable success. Worldwide, the average woman in the early 1970s had close to six children, a number that has now fallen below three. World population, now over six billion, will continue to increase—to not much more than nine billion by many estimates. Most of that increase is built into the age structure of the population; i.e., the growing number of couples now coming into their childbearing years. Nine billion will be harder to support than six billion, but the momentum of population increase has been broken.

No such break has yet occurred in the consumption curve, which is bad news because, more than sheer numbers, that rising level of consumption among an ever larger portion of the world’s population is what drives global warming. In fact, fossil fuel use is so low in the regions where population growth remains high (parts of Africa, for instance) that, with regard to climate change, Mr. Schill’s assumption that it serves as a “simple multiplier” is happily mistaken. I must say that I’ve always found the contrast between these two curves odd. Intuitively, I would have expected human fertility to be hardwired in some Darwinian fashion, and consumption to be much more pliable. So far that seems not to be true—even in our country, where the effects of too much consumption are almost comically visible in oversized houses, cars, and waistlines, growth remains our credo.