The U.N. says the world’s population will reach a milestone this Monday — 7 billion people. Since 1927, our population has soared from 2 billion to 4 billion in 1974, and 6 billion in 1999.
As stated on USENET newsgroups, officials in India predicted the baby bringing the population to 7 billion would be born Monday in Uttar Pradesh, India’s most populous state, with an estimated 200 million people. The U.N. Population Division says Monday’s date is symbolic, acknowledging it is impossible to know for sure the specific time or day when the 7 billionth person is born.
The world is adding more people in less time while the annual growth rate is slowing down — from 2.1% in the late 1960s to 1.2% today — reflecting lower birth rates. There are over two babies born every second, so the global population is forecast to hit 8 billion in about 14 years and 10 billion by the end of the century.
Can Earth support seven billion or nine billion or 10 billion people in a good life for a long time?
Thats the question that’s burning up many newsgroup discussions today. With both more people and longer lifetimes, humanity’s absolute numbers continue to rise, even though the number of children per women has halved since 1950. In fact, the absolute growth rate in human population peaked at 2.1 percent between 1965 and 1970.
The world’s richest 500 million people produce half the world’s carbon dioxide emissions—the primary greenhouse gas responsible for climate change—whereas the poorest three billion emit just seven percent. The average American—one of 312.5 million—uses up some 88 kilograms of stuff daily: food, water, plastics, metals and other material goods. Americans consume a full 25 percent of the world’s energy despite representing just 5 percent of global population, and the band of industrialized nations combine to waste 222 million metric tons of food per year, according to the U.N. Food and Agriculture Organization.
Ultimately, the limiting factor may come down to what the late economist Julian Simon called the “master resource”: energy. Simply put, is there enough energy that can be harnessed to provide a rewarding lifestyle to however many billion of us inhabit the planet? Those limits are already being pushed, as can be seen in the large increases in the price of everything from oil to food over the last decade.
As for how many people the planet can sustain, the first such estimate came from microbiologist Anton van Leeuwenhoek who calculated roughly 13.4 billion people back in 1679, based on the population density of his native Holland and its size relative to the rest of the globe. More modern guesses are hardly more scientific, ranging from one billion to one trillion.
As it is, the world produces enough food to feed everyone alive today—and more. Globally, farms produce enough calories to support a population of roughly 11 billion people fed 2,000 calories per day. That’s because human ingenuity—such as the modern breeding of staple crops, such as wheat, for higher yields, known as the Green Revolution—has outpaced, so far, environmental limits.
As it stands, the people of the planet seem to be leaning toward a peak in population followed by a gradual decline—a 21st-century world of the aged, which can be seen today in Japan or parts of Europe—but there is still a good chance of continued growth in our numbers. The U.N. had more recently predicted a leveling off at nine billion but now says we will reach the 10.1 billion figure in 2100—and potentially keep climbing as birth rates have not fallen as far or as fast as previously anticipated. If the choices we make are a little different, there could be as many as 16 billion of us by the end of this century—and that number may prove more than the planet can bear if our lifestyles don’t keep pace with our numbers.