In an era of changing climate and sinking economies, Malthusian limits to growth are back—and squeezing us painfully. Whereas more people once meant more ingenuity, more talent and more innovation, today it just seems to mean less for each. Less water for every cattle herder in the Horn of Africa. (The United Nations projects there will be more than four billion people living in nations defined as water-scarce or water-stressed by 2050, up from half a billion in 1995.) Less land for every farmer already tilling slopes so steep they risk killing themselves by falling off their fields. (At a bit less than six tenths of an acre, global per capita cropland today is little more than half of what it was in 1961, and more than 900 million people are hungry.) Less capacity in the atmosphere to accept the heat-trapping gases that could fry the planet for centuries to come. Scarcer and higher-priced energy and food. And if the world’s economy does not bounce back to its glory days, less credit and fewer jobs.
It’s not surprising that this kind of predicament brings back an old sore topic: human population and whether to do anything about it. Let’s concede up front that nothing short of a catastrophic population crash (think of the film Children of Men, set in a world without children) would make much difference to climate change, water scarcity or land shortages over the next decade or so. There are 6.8 billion of us today, and more are on the way. To make a dent in these problems in the short term without throwing anyone overboard, we will need to radically reduce individuals’ footprint on the environment through improvements in technology and possibly wrenching changes in lifestyle.
But until the world’s population stops growing, there will be no end to the need to squeeze individuals’ consumption of fossil fuels and other natural resources. A close look at this problem is sobering: short of catastrophic leaps in the death rate or unwanted crashes in fertility, the world’s population is all but certain to grow by at least one billion to two billion people. The low-consuming billions of the developing world would love to consume as Americans do, with similar disregard for the environment—and they have as much of a right to do so. These facts suggest that the coming ecological impact will be of a scale that we will simply have to manage and adapt to as best we can.
Population growth constantly pushes the consequences of any level of individual consumption to a higher plateau, and reductions in individual consumption can always be overwhelmed by increases in population. The simple reality is that acting on both, consistently and simultaneously, is the key to long-term environmental sustainability. The sustainability benefits of level or falling human numbers are too powerful to ignore for long.
In the U.S., this discussion remains muted all the same. Population concerns may lurk within the public anger over illegal immigration or over the unwed California mother of octuplets earlier this year. But to the extent that the news media address domestic population growth at all, it is through euphemisms such as “sprawl” (the theoretical culprit in pollution of the Chesapeake Bay, for example) or the economy (the theoretical driver of increased greenhouse gas emissions). You are more likely to read about population growth in a letter to the editor than in a news story or editorial.
When President-elect Barack Obama pledged in late 2008 to bring U.S. carbon dioxide emissions to their 1990 levels by 2020, environmentalists struggled to swallow their dismay. The European Union, after all, had committed itself to 20 percent reductions from 1990 levels. But on a per capita basis, President Obama’s pledge was somewhat more ambitious than the E.U.’s was. Because of much more rapid population growth than in the E.U., Americans would be cutting their individual emissions by 26 percent under his plan and Europeans by 25 percent under theirs. Any pledges to lower emissions by a uniform percentage among industrial countries will be much harder for the U.S. to achieve, simply because it is gaining people so fast through immigration and a birthrate that is higher than average for a developed nation.