Earth’s population of nearly 6 billion, which is projected to double in the next 40 years, is already about three times larger than what the planet can sustain in prosperity, a Cornell University ecology professor reported Monday.
David Pimentel presented the results of a new population study to the annual meeting of the American Association for the Advancement of Science.
Limitations of fertile land, forests and water dictate that the planet can accommodate only about 2 billion people living a comfortable life, Pimentel said.
“Granted, a drastic demographic adjustment to 2 billion humans will cause serious social, economic and political problems,” Pimentel said. “But continued rapid population growth will result in even more severe social, economic and political conflicts as well as catastrophic public health and environmental problems.”
Pimentel’s report, based on a yearlong study by several Cornell researchers, will be published in the May issue of Population and Environment. It was based upon widely accepted estimates of the natural resources necessary to sustain human life.
Researchers refer to species of plants, animals and microbes that provide essential functions for humanity as the natural biota.
“Humans have no technologies to substitute for most services provided by wild biota,” Pimentel said.
Even as the world’s population continues to grow, he said, there are many signs that nature cannot sustain the people already living. In the past 40 years, nearly one-third of the world’s cropland has been abandoned because of erosion, salinization and waterlogging, he said.
In the U.S., there are about 1.2 acres of cropland for each person, but the worldwide average is only 0.7 acres per person, Pimentel said, and continuing land degradation is driving that figure down.
“This shortage of productive cropland is part of the cause of food shortages and poverty that many humans are experiencing today,” he said.
In the face of runaway population growth, many public policies in the U.S. are counterproductive and encourage the world’s people to have more children, another speaker said.
Virginia Abernethy, a Vanderbilt University anthropology professor, said facts don’t support the widely held belief that as people become more prosperous, they limit the size of their families.
Fertility in Africa, which once had been moderate, increased sharply to six children per woman during the 1960s when health-care availability and literacy rose and foreign aid contributed to general economic optimism, Abernethy said.
By contrast, difficult economic times tend to depress fertility, she said.
In Burma, which has a chaotic economy and virtually no modern birth control, fertility has fallen by 20 percent as couples delay marriage, she said. A similar trend is occurring in parts of northern Africa where unemployment runs as high as 50 percent.
American policies providing generous aid to poor countries and liberal immigration send the wrong message, Abernethy said.
“Either policy is likely to be read by couples in the Third World as a sign that wealth is abundant and opportunity beckoning,” she said. “This interpretation neutralizes economic and environmental information that would otherwise motivate people to exercise marital and reproductive caution.”
