The effects of population growth on the earth are as controversial as the numbers of people. At a meeting of the International Botanical Congress in St. Louis this summer, scientists from Oregon State University and Stanford University reported that nearly half the earth's land mass already has been changed by human activity - wetlands filled in, forests cut down, prairies plowed under. There's also been an increase in red tides and other harmful algal blooms around the world - most in response to a flush of nutrients. We're also seeing increased water temperature, possibly from global warming. Related to this loss of habitat, Dr. Lubchenco told the St. Louis gathering that rates of plant and animal extinction are many times higher than would otherwise be the case.
Pedestrians push their way through a traffic jam in downtown Lagos, Nigeria.
The city is one of the most over-populated cites in the world. It's too simple to say that countries with a high growth rate are more responsible for environmental problems of pollution and resource depletion, many analysts agree. By this gauge, Americans, Canadians, Europeans, and others of relative wealth have a much greater impact than those in poorer countries. Critics respond to such assertions in two ways. Between 1974 and 1995, rice production in China increased by 88 percent.