National Geographic : 2011 Jan
• made me start thinking like Leeuwenhoek. If in 2045 there are nine billion people living on the six habitable continents, the world popula- tion density will be a little more than half that of France today. France is not usually considered a hellish place. Will the world be hellish then? Some parts of it may well be; some parts of it are hellish today. ere are now 21 cities with populations larger than ten million, and by 2050 there will be many more. Delhi adds hundreds of thousands of migrants each year, and those peo- ple arrive to nd that "no plans have been made for water, sewage, or habitation," says Shailaja Chandra. Dhaka in Bangladesh and Kinshasa in the Democratic Republic of the Congo are 40 times larger today than they were in 1950. eir slums are lled with desperately poor people who have ed worse poverty in the countryside. Whole countries today face population pres- sures that seem as insurmountable to us as India's did to Ehrlich in 1966. Bangladesh is among the most densely populated countries in the world and one of the most immediately threatened by climate change; rising seas could displace tens of millions of Bangladeshis. Rwanda is an equally alarming case. In his book Collapse, Jared Dia- mond argued that the genocidal massacre of some 800,000 Rwandans in 1994 was the result of several factors, not only ethnic hatred but also overpopulation---too many farmers dividing the same amount of land into increasingly small pieces that became inadequate to support a farm- er's family. "Malthus's worst-case scenario may sometimes be realized," Diamond concluded. Many people are justifiably worried that Malthus will nally be proved right on a global scale---that the planet won't be able to feed nine billion people. Lester Brown, founder of World- watch Institute and now head of the Earth Policy Institute in Washington, believes food shortag- es could cause a collapse of global civilization. Human beings are living off natural capital, Brown argues, eroding soil and depleting groundwater faster than they can be replenished. All of that will soon be cramping food produc- tion. Brown's Plan B to save civilization would put the whole world on a wartime footing, like the U.S. a er Pearl Harbor, to stabilize climate and repair the ecological damage. "Filling the family planning gap may be the most urgent item on the global agenda," he writes, so if we don't hold the world's population to eight billion by reduc- ing fertility, the death rate may increase instead. Eight billion corresponds to the UN's lowest projection for 2050. In that optimistic scenario, Bangladesh has a fertility rate of 1.35 in 2050, but it still has 25 million more people than it does today. Rwanda's fertility rate also falls below the replacement level, but its population still rises to well over twice what it was before the genocide. If that's the optimistic scenario, one might argue, the future is indeed bleak. But one can also draw a di erent conclusion--- that xating on population numbers is not the best way to confront the future. People packed into slums need help, but the problem that needs solving is poverty and lack of infrastructure, not overpopulation. Giving every woman access to family planning services is a good idea---"the one strategy that can make the biggest di erence to women's lives," Chandra calls it. But the most aggressive population control program imag- inable will not save Bangladesh from sea level rise, Rwanda from another genocide, or all of us from our enormous environmental problems. Global warming is a good example. Carbon emissions from fossil fuels are growing fastest in China, thanks to its prolonged economic boom, but fertility there is already below replacement; not much more can be done to control popu- lation. Where population is growing fastest, in sub-Saharan Africa, emissions per person are only a few percent of what they are in the U.S.--- so population control would have little e ect on climate. Brian O'Neill of the National Center for Atmospheric Research has calculated that if the population were to reach 7.4 billion in 2050 instead of 8.9 billion, it would reduce emissions by 15 percent. " ose who say the whole prob- lem is population are wrong," Joel Cohen says. "It's not even the dominant factor." To stop global warming we'll have to switch from fossil fuels to alternative energy---regardless of how big the population gets.