WASHINGTON - The global population has been ticking upwards rapidly, almost doubling in a little more than 40 years.
As the world marked the birth of its seventh billionth person Monday, producers of the new documentary "Hooked on Growth" warned Earth soon won't be able to handle so many people.
"If we don't solve the population problem, our global society is over a cliff," explained Bill Ryerson, president of the Population Institute.
"We keep thinking we can grow forever," added University of Colorado professor Al Bartlett. "And the resource limitation is upon us."
"Human beings have used more natural resources since the end of World War II than in all of human history before," said Bill McKibben, author of Deep Economy.
"hooked on Growth" was created by GrowthBusters, a group devoted to revealing the threat of over-consumption and population growth.
In a public service announcement, GrowthBusters leaders even asked people to limit how many children they have.
"Instead of a miserable future for lots of children, let's create a magnificent future for fewer children," an announcer said in the "Population Decline is Part of the Solution" ad.
But Steven Mosher, president of the Population Research Institute, said groups like GrowthBusters have it all wrong -- under-population is in our future and a much bigger threat.
"Too few people to buy homes and cars. Too few people to start new businesses. Too few people to pay into pension funds and retirement programs and keep Social Security afloat," he said. "Why is Greece rioting? Look at those rioters. They're all gray-haired. There are too few young people to keep the Greek economy going."
Unlike other groups, The Population Research Institute celebrated the birth of the seven billionth baby, and welcomed many more to be born.
Mosher says America is for now managing to replace its population, but the situation will grow dire soon in some European nations.
"People in Italy and Spain are averaging about one child per couple. That means each generation is half the size of the previous generation," he explained.
"It doesn't take long to cut your population in half, then in half again. There are going to be tens of millions fewer Italians in the year 2100 unless they start having children," Mosher added. "Now, I like the Italians. I'm going to miss them. But if they don't start reproducing, they're gone."