The planet may not feel any different today, but there are now 7 billion people on it, according to the United Nations.
That number will continue to rise, of course, and global incomes are likely to rise as well. That means more cars and computers, and bigger homes: the kinds of things Americans take for granted. It’s that rise in consumption that has population experts worried.
Klaus Lackner, a physicist at Columbia University’s Earth Institute, says as economies improve in places like India and Africa — where populations are growing fastest — they’re going to want to live more like we do.
"It’s very hard to convince people to stop consumption," he says.
But maybe the world’s next billion will be happy with Hondas instead of Hummers.
"I would expect consumption in the future gets larger, but we also learn how to do things more efficiently," Lackner says, "so the raw material consumption may well go down."
But Lackner says consumption will eventually go up again; you can only tighten your belt so much. Physicist Daniel Kammen at the University of California, Berkeley, says there just isn’t much incentive for rich countries to do that anyway.
The U.N.’s prediction for future growth includes high, medium and low estimates.