Dan Gardner is the New York Times best-selling author of Risk, Future Babble, Superforecasting (co-authored with Philip E. Tetlock), and How Big Things Get Done (co-authored with Bent Flyvbjerg). His books have been published in 26 countries and 20 languages. Prior to becoming an author, Gardner was an award-winning investigative journalist. More >

7 Billion People Is No Reason For Panic Or Complacency

According to the United Nations, the world's population will top seven billion on Oct. 31. By 2050, there will likely be more than nine billion people on Earth.

So how do you feel about that? For many, these statistics are frightening as hell. Soaring population will surely lead to famine, resource depletion, poverty, disease, war, and environmental calamity. But for others - probably fewer in number - they are nothing to worry about. More people means more minds, more innovation, more technology, more wealth, and a better world.

These are the two extreme camps that have dominated debates about global population since the 1950s, or even the end of the 18th century, when the Reverend Thomas Robert Malthus gloomily forecast that rising populations would necessarily outstrip food supply until starvation, disease, and war drove them back down. The pessimists are naturally known as Malthusians. The optimists, who see only a horn of plenty in our future, are the Cornucopians.

Both sides are wrong. And it's critical that we understand why.

In the 19th century, Malthus's grim forecasts were defeated by advances in technology and human settlement. Agriculture not only kept the steadily growing number of mouths fed, it fed them better than ever.

In 1804, there were a billion people. The two-billion mark was crossed in 1927.

The first two best-selling books setting out the modern Malthusian case were published in 1948. The world's population stood at 2.38 billion.

In 1960, the population explosion made the cover of Time. There were a little more than three billion people on the planet.

In 1967, another influential best-seller was published. The thesis of Famine: 1975 was nicely summed up in the title. The following year, biologist Paul Ehrlich published The Population Bomb, which predicted mass global starvation in the 1970s and 1980s. Global population was 3.5 billion.

Millions of copies of The Population Bomb were sold and Ehrlich became a much-honoured environmentalist and a guru among modern Malthusians.

In paper after paper, book after book, Ehrlich insisted that starvation, disaster, anarchy, even civilizational collapse, were imminent. There was no escaping it.

The explanation lay in a simple formula: I = P x A x T. The "I" stands for humanity's impact on the natural world. It is equal to the combined total of Population, Affluence, and Technology.

So more people, more wealth, and more technology would inevitably destroy the natural support systems we depend on. And produce catastrophe.

Except it didn't work out that way. As I detailed in my book Future Babble, almost all Ehrlich's predictions were wrong. In fact, over the following 40 years, many key trends - global mortality rate, per capita food production, air and water pollution - did the opposite of what Ehrlich expected.

The Malthusians' basic mistake was to underestimate - again - the extent to which new technology could ramp up food production. This time it was the "Green Revolution," which used new plant varieties and chemical fertilizers to dramatically boost harvests.

But more fundamentally, the Malthusians misunderstood affluence and technology, which can increase the burden humanity puts on the environment but don't necessarily do so. In fact, they can ease it. When nations reach a certain level of affluence, for example, they invariably impose tighter controls on pollution. In effect, that is affluence paying to lessen impact.

Same with technology. That's the whole idea behind "green energy," and other green technologies - which affluent nations are better able and more willing to pay for.

But being a Malthusian means never having to say you're sorry: This week, Paul Ehrlich told The Guardian there is only a 10-percent chance of avoiding the collapse of global civilization in the coming decades.

Cornucopians love to talk about the many mistakes of Paul Ehrlich and the Malthusians because they treat them as proof they are right. Which is a mistake.

Go back and look at what Paul Ehrlich's Cornucopian critics were saying in the 1960s and 1970s and you'll find many weren't much better at predicting the future than Ehrlich.

True, they were right that the Malthusians' disaster scenarios wouldn't come to pass. But they were wrong about why. They said desalination would make all the difference. Or giant undersea kelp farms. Or dirt-cheap nuclear power. Wrong, wrong, wrong.

The more circumspect Cornucopians didn't try to predict how technology would evolve, however. They merely said human ingenuity was wonderful and it would take care of any problem posed by rising population. Which is closer to the truth. But it's still wrong.

The ingenuity that saved the world from starvation didn't just happen, like a sudden cloudburst over a drought-stricken land: The Green Revolution was the product of decades of laborious research and the vast sums of money - public and private - that paid for it.

Norman Borlaug understood this better than anyone, which is why the "father of the Green Revolution," who is lionized by Cornucopians, was not a Cornucopian.

In 1970, Borlaug won the Nobel Peace Prize. There isn't a trace of blithe confidence in his acceptance speech, not the slightest assumption that everything will work out just fine. Instead, Borlaug emphasizes the gravity of the problem - "most people still fail to comprehend the magnitude and menace of the 'Population Monster' " - and calls for greater efforts to feed, educate, house, and care for the world's poor.

On Wednesday, the UN released a report on the state of the world's population that confirmed, again, that much of what Borlaug called for has been done. Humanity collectively is healthier and wealthier than ever.

And the future? The UN report got that exactly right.

Nothing is inevitable, it said. We could have "a healthy, sustainable, and prosperous future." Or it could be one "marked by inequalities, environmental decline and economic setbacks."

What we decide now will determine our fate.