Environment Science

The global rate of human population growth peaked around 1963, but the number of people living on Earth—and sharing finite resources like water and food—has grown by more than two-thirds since then, topping out at over 6.6 billion today. Human population is expected to exceed nine billion by 2050. Environmentalists don’t dispute that many if not all of the environmental problems—from climate change to species loss to overzealous resource extraction—are either caused or exacerbated by population growth.

According to Population Connection, population growth since 1950 is behind the clearing of 80 percent of rainforests, the loss of tens of thousands of plant and wildlife species, an increase in greenhouse gas emissions of some 400 percent and the development or commercialization of as much as half of the Earth’s surface land.

The group fears that in the coming decades half of the world’s population will be exposed to“water-stress” or “water-scarce” conditions, which are expected to “intensify difficulties in meeting…consumption levels, and wreak devastating effects on our delicately balanced ecosystems.”

And while population numbers in most developed nations are leveling off or diminishing today, high levels of consumption make for a huge drain on resources. Americans, who represent only 4 percent of world population, consume 25 percent of all resources.

Industrialized countries also contribute far more to climate change, ozone depletion and overfishing than developing countries. And as more and more residents of developing countries get access to Western media, or immigrate to the United States, they want to emulate the consumption-heavy lifestyles they see on their televisions and read about on the Internet.

* Nearly half the world's people are crowded into urban areas, often without adequatesanitation, and are exposed to epidemics of measles, influenza and other diseases.

* With 1.2 billion people lacking clean water, waterborne...