The current unrest in the Arab nations has called the world's attention to some of the political and economic consequences of the West's addiction to petroleum. But sadly it hasn't brought back into focus two more fundamental and interrelated problems. The first is the population explosion; the second is the expectation of perpetual growth in per capita consumption, not just for several billion poor people, but for the billion or so who are already rich.
In the next forty years the populations of already-water short Arab nations are going to increase dramatically, and at the same time their people will be aspiring to catch up with the living standards of today's developed countries. For example, Egypt, with 80 million people today, is projected to grow to some 138 million by 2050. Per capita income in Egypt is now about $5,500, compared with about $47,000 in the United States and $30,000 in the European Union.
The aspiration gap is even more stunning for sub-Saharan Africa, which is projected to explode from 870 million people to 1.8 billion in the next 40 years. Per capita income there is now $2,000, and less than a third of the population has access to a toilet. That gap will doubtless widen further as the poor suffer disproportionately from climate disruption, the spread of toxic chemicals, and an extinction episode unmatched in 65 million years, threatening the natural services upon which people are utterly dependent. Given the additional need to invest in completely re-engineering the planet's energy-mobilizing and water-handling infrastructure and rising pressure on resources, even maintaining today's standards of living in both rich and poor nations will be increasingly difficult.
The press is full of stories about problems caused at least in part by the conjoined but unmentionable twin elephants of population growth and overconsumption. But spiking food and energy prices, water shortages, increasingly severe weather, melting ice caps, dying coral reefs, intersex alligators, disappearing polar bears, collapsing infrastructures, terrorism, and novel epidemics are almost never connected to the elephants. While obviously there are limits to sustainable human numbers and to humanity's aggregate consumption, those limits are almost never discussed.
Indeed, when the Census Bureau announced in 2010 that the United States had passed 308 million people, it was treated as some sort of triumph, with emphasis placed on reallocation of congressional seats. No mention that we "plan" to add more than 110 million more by 2050 and then grow to infinity (don't hold your breath). We expect no better media analysis when the global population rockets past 7 billion this year -- much more than tripling the population in our own lifetimes. Will the media explain that the additional 2 billion people expected in the next thirty-five years will do much more environmental damage than the previous two billion? Human beings are smart; they pick the low-hanging fruit first -- and we have. Every additional person now, on average, must be fed from more marginal land, supplied with water from more distant or difficult to purify sources, and use minerals won from ever-poorer ores.
Will technology save us? It can help, but its record is generally dismal. When The Population Bomb was published in 1968, there were 3.5 billion people, and we were called alarmist -- technology could feed, house, clothe, educate, and provide great lives to even 5 billion people. Nuclear agro-industrial complexes or growing algae on sewage would feed everyone. Well, they didn't. Instead, the roughly half-billion hungry people then have increased to about a billion, and a couple billion more are living in misery. Why don't the growth maniacs stop asserting how many billions more people we could care for and focus first on stopping population growth and giving decent lives to all the people already here? And spare us that old bromide about how the next kid may turn out to be the Einstein who saves us; considering the rich-poor gap, it's more likely to be an Osama Bin Laden bent on destroying us.
There is sometimes confusion among environmentalists about the relative roles of population and per-capita consumption in causing environmental deterioration. But one can no more separate them than distinguish the multiplicative roles of a rectangle's length or width in contributing to the area of a rectangle. One can, however, determine their parts in changing the area (or, analogously, the environmental damage).
For instance, in the past two centuries, population growth and expanding per capita consumption have contributed roughly equally to humanity's assault on its life-support systems. Reducing the assault and transitioning to a sustainable society will require action on both factors. It will take much longer to humanely reduce population size than to alter human consumption patterns. Many decades of moderately reduced fertility would be required to have a significant effect on human numbers, but with enough incentive, consumption patterns can be transformed very rapidly, as World War II mobilizations showed dramatically. Because of that time difference, moving toward population reduction now in the U.S. and globally is required if humanity is to attain a sustainable civilization. But if overconsumption by the rich continues to escalate, the benefits of ending population growth will be compromised. And if underconsumption by the poor is allowed to continue or worsen, then the cooperation we need to resolve the human predicament is unlikely to materialize. Equity issues and environmental issues are also conjoined twins.
Paul R. Ehrlich and Anne H. Ehrlich are in the Department of Biology of Stanford University. They are co-authors of The Dominant Animal, and Paul's latest book, co-authored with psychologist Robert Ornstein, is Humanity on a Tightrope.