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The world’s population topped the 6 billion mark Tuesday, with the birth of a baby in Sarajevo. To some, that’s cause for celebration. We are healthier and living longer than ever before. But others worry the milestone is actually a harbinger of doom: they fear further environmental degradation and human suffering. And still others say we are misinterpreting the number entirely by overlooking the downward trend in global birthrates.

Whatever the truth, the United Nations Population Fund designated Oct. 12 as “The Day of 6 Billion.” U.N. Secretary-General Kofi Annan symbolically welcomed a baby boy born in Sarajevo as number 6 billion.

“I heard others talking about a six billionth baby but I found out from the doctors that it’s mine,” said Fatima Nevic, who gave birth to the 8-pound boy at Sarajevo’s hospital.

“I still don’t know what name he will have. Regardless of whether he’s the six billionth baby or not, I’m a happy mother,” she said.

The date, to be sure, is more symbolic than scientific, meant to mark the moment when the world’s population passes that threshold. The figure, with all those zeros, has a millennial feel, and will be certain to garner a fair share of media attention. But what does the number mean?

Image: Mother Kisses Sixth Billionth Baby In Sarajevo Hoispital
Fatima Nevic kisses her son, who was symbolically welcomed as Earth's sixth billionth person Tuesday.
For one thing, it means that the population of the world has doubled in less than four decades. Similarly, it means that a tenth of all the people who have ever lived are now alive.

Yet it also shows how quickly the rate of population growth has slowed since the alarms about the consequences of overpopulation began sounding in the 1960s. Since 1992, the United Nations has had to push back its 6 billion estimate by almost two years.

“This slowing of population growth is not inevitable. The work of many people over the last 30 years made it possible. Whether it continues, and whether it is accompanied by increasing well-being or increasing stress, will depend on choices and action in the next 10 years,” a U.N. population reports issued last month said.

‘Good news, bad news’
“This is a classic good news, bad news story,” said Alex Marshall of the United Nations Population Fund. “No one in history thought it would be possible to reach this number with an intact planet; they predicted ecological collapse, famine and nuclear war, but we are doing rather well and that’s an achievement. But the other side is that so many people are living in desperate poverty and the population is still growing, mostly in the poorest countries to the poorest families.”

U.N. demographers project 2.9 billion people will be added to the planet in the next half-century, fewer than the 3.6 billion added during the past 50 years. But, in contrast to 50 years ago, when populations were growing everywhere, growth is now primarily occurring in developing countries.

“A population the size of Germany is being added to the world each year, which would be fine if it had the resources of Germany, but it doesn’t,” said Marshall.

The United Nations Population Fund and environmental groups like the , and are concerned about what a growing population means for the environment and for the quality of life in developing countries.

Brian Halweil, a researcher at the Worldwatch Institute, said “The Day of 6 Billion” should be seen as a rallying point for population issues, the most pressing of which, he said, are freshwater shortages and unemployment.

U.N. projections
The U.N.’s medium projection that the world population will hit 8.9 billion in 2050, while regarded as the most likely scenario, is not inevitable. U.N. demographers have issued a range of projections for the 2050 world population, from 7.3 to 10.7 billion.

And the general consensus, as expressed by 180 nations in the 1994 Cairo population conference and reiterated in another U.N. conference this July, is that the world’s population growth rate should be slowed by providing women with more educational and family planning opportunities.

But the U.N. report finds that international assistance is lagging and some of the world’s richest nations are not providing the funds needed for programs aimed at curbing population growth.

“Unless funding increases substantially, the shortfall could spell continued high rates of unwanted pregnancy, abortion, maternal and child deaths, and an even faster spread of HIV/AIDS. The shortage of funding also means that progress towards human rights and equality in health care will be slower than ever,” the U.N. report said.

“We really talk about giving people choices,” said Peter Kostmayer, a former U.S. Congressman who is now executive director for Zero Population Growth. “The important thing is empowering people and then you don’t have to worry about ecological terms like carrying capacity.”

Although women today are having half as many children as their mothers did, more than 78 million people are being added to the planet each year, far more than in 1963, when the growth rate peaked. And high fertility 20 years ago has resulted in around 1 billion people between the ages of 15 and 24 - a larger group of people coming into their reproductive years than this planet has ever seen.

“The decisions taken in the next decade will determine how fast the world adds the next billion people and the billion after that, whether the new billions will be born to lives of poverty and deprivation, whether equality will be established between men and women, and what effects population growth will have on natural resources and the environment,” the report said.

To critics like Sheldon Richman, editor of the libertarian publication “The Freeman,” the hype surrounding Oct. 12 is misplaced. The pattern of increasing life expectancy and decreasing death rate is simply the result of progress, he said.

“People are living longer and healthier lives than ever before and this is not consistent with the idea we can overpopulate the earth,” he said.

Skeptics like Richman say that since Malthus predicted war and famine 200 years ago in his “Essay on the Principle of Population,” concerns about the consequences of overpopulation have been baseless.

The birth dearth
Ben Wattenberg, senior fellow at the American Enterprise Institute, a conservative think-tank, argues that focusing on the planet’s past population explosion is overly simplistic. World population is a complicated issue, he said, and the more significant demographic trend is what he calls the “birth dearth” - a term referring to the declining birth rate.

It took all of time until 1804 for the world’s human population to reach 1 billion. But at the population’s current growth rate, it only takes about 12 years to add a billion people to the planet. Despite the slowing rate of growth since the 1960s, the net population growth since World War II means that even though people are multiplying at a slower rate, there are so many more people multiplying that the total number of people on the planet continues to grow.

Demographers call this phenomenon population momentum and compare it to having a huge amount of money in the bank - even if interest rates are low, your money will still grow. The U.N. estimates that the momentum will not expire until around 2050, when the declining birth rate will stabilize the world’s population.

Marshall at the United Nations Population Fund admits that there are many questions remaining about how many people our planet can support, but said that is exactly why we need to slow population growth, to buy time in order to answer questions about the sustainability of the planet and solve problems like malnutrition and unemployment.

Stanford ecologist Paul Ehrlich, whose 1968 book “The Population Bomb” echoed Malthusian scenarios and made “overpopulation” a topical issue, said population growth isn’t the only concern. Ehrlich still argues our current population level is three times what it should be. He said that the earth’s optimal population size is around 2 billion.

Economy vs. ecology
The debate over how many people are too many has pitted ecologists and economists against each other since the 1960s.

Joel Cohen, a populations professor at Rockefeller University and Columbia University, said that the disagreement is inherent in the way each of these disciplines looks at the world.

“Ecologists look at it in terms of natural restraints and economists emphasize human choices and usually both sides are more confident that their sides are right than the facts warrant,” he said.

Much of the disagreement hinges upon the idea that there is a maximum number that the earth can support, known among ecologists as a carrying capacity.

“The idea of carrying capacity doesn’t apply to the human world because humans aren’t passive with respect to their environment,” said Richman of “The Freeman.” “Human beings create resources. We find potential stuff and human intelligence turns it into resources. The computer revolution is based on sand; human intelligence turned that common stuff into the main component of an amazing technology.”

But Halweil of Worldwatch disagrees, “It’s conceivable for economists to look at trends as going upwards infinitely, but natural systems don’t behave in the same way. There are thresholds in terms of natural systems.

“Perhaps we could cut down all the rainforests and harvest all the ocean fish out of existence and we could replace them with other resources, but that doesn’t really account for destroying two ecosystems.”

Ehrlich said that on top of the problems caused by the sheer numbers of people inhabiting the planet are those caused by increasing consumption patterns.

“Superconsumption is the other problem,” he said. “And this behavior may be more difficult to change. We have had some success with birth rates but we have no clue how to get off superconsumption.”

Cohen said the notion of a carrying capacity, which is closely tied to our consumption patterns, is a source of much debate because it isn’t as obvious for humans as for other animals because humans are more adaptable to environmental changes.

“When you overexploit an area people respond; people aren’t like deer who will just starve to death,” he said. “The notion of carrying capacity depends on how we want to live.”

This idea that overpopulation depends on what kind of world we want to live in summarizes the conclusion of Cohen’s book “How Many People Can the Earth Support?” and the environmentalists’ viewpoint.

“When I hear the question ‘How many people can the earth support?,’ what I hear is, ‘What level of environmental degradation and human suffering are we willing to put up with?” said Halweil.

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