For decades now, demographers and economists have warned that the number of people on earth is growing too fast to be "sustainable."
But for many, this story is somewhat old, perhaps alarmist.
"We have sort of a cornucopia fantasy," says Russell Hopfenberg, a consulting faculty member at Duke University in Durham, N.C. "People say, 'Not to worry. Technology will solve the problem.' "
Mr. Hopfenberg isn't so sure. "Don't get lulled into complacency," he says.
Some relevant facts include:
•The population of the United States was estimated at 299,083,490 last Wednesday by the US Census Bureau's "population clock" website (www.census.gov/main/www/popclock.html). That figure is projected to reach 300 million by October. Compared with many countries, the US is lightly populated. Nonetheless, its population growth rate is comparable to that of China. Because of immigration, the number of people in the US could reach 400 million by 2050.
•Another clock on the Census Bureau website puts the world's population at 6,524,983,762. The United Nations projects that number will reach 9.1 billion by 2050. About 76 million people are being added annually.
•This year's world grain harvest is projected to fall short of consumption by 61 million tons. That's the sixth time in the past seven years that production has failed to satisfy demand, notes Lester Brown, president of the Earth Policy Institute in Washington.
He expects the world carry-over stocks of grain, a basic measure of food security, to fall to 57 days of consumption by the end of this crop year. That level stands as the shortest buffer since a 56-day-low in 1956 doubled grain prices.
So prices could rise again.
Despite continued growth in world food output with advances in science, technology, and the application of knowledge, the developing world still had 815 million hungry people in 2002, only 9 million less than in 1990, according to the Food and Agricultural Organization. The number of hungry people actually rose between 1997 and 2002.
Such facts often touch on the news.
Population pressure in Mexico, Central America, and elsewhere has encouraged the flood of illegal immigrants in the US, and thus the ensuing national debate on possible remedies.
Warren Buffett, one of the world's wealthiest men, undoubtedly recognized population-related problems in announcing last week plans to donate $37.4 billion of Berkshire Hathaway Inc. stock to several foundations. These include some he's created that emphasize family planning, abortion rights, environmental and conservation issues, and education for low-income children.
Duke's Hopfenberg says he is not a modern-day Malthusian predicting widespread famine. In 1798, Thomas Robert Malthus, an ordained minister of the Church of England, published an "Essay on Population" that became renowned. It maintained that unchecked population growth always exceeds the growth of means of subsistence. This leads to "positive checks" of starvation, disease, and the like, as well as "preventive checks," such as postponement of marriage that decreases births.
Hopfenberg postulates that human beings are similar to other animals. As food availability increases, the population of animals and people will grow. As examples, he cites research on Seychelles warblers, musk shrews, rabbits, monkeys, etc. And it isn't always starvation that brings their population growth to an end. Some animals regulate their fertility if food gets scarce.
In the case of humans, there must be widespread recognition that population growth is a function of increases in food availability, Hopfenberg says. That understanding is needed to bring about shifts in social, political, educational, and religious mind-sets. Otherwise, he speculates, increased disease and death rates may ultimately control population growth.
Christopher Flavin, president of the Worldwatch Institute in Washington, figures other factors will brake population growth. They include environmental changes, resource restraints, and a decline in the quality of life. World oil output is predicted to peak within 15 years. Fresh water in some areas is already in short supply. Farmland is being chewed up by swelling suburbia. Global warming, with its rising sea levels, will force hundreds of millions of people out of coastal regions in the next century or so. As a result, Miami, New York, and many other cities around the world "will not exist in their current form," Mr. Flavin predicts.
One way to boost the world's food supply would be a change in eating habits. If people ate more grains and vegetables and less meat, the world could feed another billion people, Flavin says.
The average American consumes 20 times as much in natural resources as the average African, he notes. If all the people in the world consumed at the average level of high-income countries, the planet could sustainably support only 1.8 billion people – not the actual 6.5 billion.
Hopfenberg doubts that measures to encourage widespread family planning will adequately restrain the world's population. Leaders must put on their thinking caps to come up with intelligent, creative, inventive measures to discourage births, he says.
As it is, every 11 seconds the Census Bureau clock adds another person to the US population. The clock will tick faster.