The population debate (A reply)

Well, yes. At any given time it often seems that there are too many people in the world, so the prospect of even more people seems downright terrifying. Yet when you look at the supposed population explosions of the past, the numbers seem downright minuscule compared to today’s.

Consider, for example, a population explosion that occurred in Britain four centuries ago. The population of England, some 3 million when Columbus discovered America, nearly doubled by 1650, to more than 5 million. Here was a genuine crisis: England’s available supply of arable land— the source of its food supply— remained finite, while the supply of trees— the source of its heat— dwindled along with other vital resources. From 25% to 50% of the English population lived in poverty. Plagues and famine were common. So many of the rural poor migrated to England’s cities in search of jobs that London’s population grew from about 200,000 in 1600 to 575,000 in 1700.

Parliament strikes back

More to the point, the English responded to this emergency by emigrating in droves to North America, which offered millions of acres of unoccupied land, not to mention abundant trees, lakes and rivers, all almost free for the taking. Those who could afford the trans-Atlantic passage leaped at the opportunity; those who couldn’t, bound themselves to American masters as indentured servants, in the hope of paying off their debts and sending for their families within a few years. In this manner the European population of America’s 13 original colonies, which numbered just a handful at the dawn of the 17th Century, expanded to 220,000 in 1690 and then soared to 1.5 million by 1760 and to 2.75 million by 1790, more than four-fifths of them English. This vast trans-Atlantic migration that we now take for granted became one of the great events in recorded history— what Bismarck called “the decisive fact in the modern world.” Do the math and you’ll realize that, by 1790, at least 25% of England’s population had pulled up stakes and moved to America.

Yet the British government did not greet this depopulation with a sigh of relief. On the contrary, by the mid-18th Century this mass exodus was widely perceived in the British government as a threat to the realm. As early as 1718, Parliament prohibited the emigration of skilled workers from the British Isles to North America. The only thing worse than too many people, the Parliamentarians apparently concluded, was not enough people— which is the very point I’ve been trying to make.

Today England’s population— just England alone, never mind Scotland, Wales or Northern Ireland— is 56 million. That’s more than ten times as many people as lived there during the supposed great explosion of the 17th Century. Today 8.3 million people live within London’s city limits alone— more than inhabited the entire country in the 17th Century. So why does no one talk of an English population explosion today? Why were 5 million people too many in 1650, and why are 56 million not too many in 2013?

For essentially three reasons, all of which we can chalk up to human ingenuity: First, agricultural innovations vastly expanded England’s food supply. Second, alternative heating fuels— like coal, oil and gas— were developed to replace wood. Third, the need to earn the income to feed their growing population gave the English the incentive to launch the Industrial Revolution. Necessity was the mother of these inventions— and the primary necessity, I would argue, was population growth.

Pre-human turmoil

But even if, as I contend, population growth has, on balance, benefitted humanity, has it benefitted the Earth and its lower animal forms? Like Tom Purdom, many scientists and people of conscience routinely hold our species responsible for overheating the Earth, polluting the atmosphere, threatening the ozone and otherwise tampering with the balance of nature. Yet by any commonly accepted definition, the turmoil produced by humans since our arrival on the planet remains tiny compared to the anarchy that reigned when natural forces were left to their own devices, unchecked by human interference.

As I discovered while researching a book on the coal industry (In the Kingdom of Coal, 2003), the Earth of some 225 to 350 million years ago was a far warmer and more humid place than it is today— so warm that much of the land in what we now call the Earth’s “temperate zones” consisted of large, muddy swamps where tropical plants, trees, ferns and mosses grew and multiplied with reckless abandon. As these plants and trees inevitably invaded each other’s turf and collided, their accumulated leaves, twigs, branches and trunks broke off and fell into the swamp bottoms or matted over the water’s surface in thick floating masses. Younger plants lived on these mats of dead plant life and eventually died as well, further swelling the accumulated plant debris.

Stagnant moisture and bacteria preserved this dead plant material and converted it into peat, a spongy substance whose primary elements— carbon, hydrogen and oxygen— are also the primary elements of coal. As these peat bogs sank beneath the surface over the course of millions of years, the heat from the Earth’s core, combined with pressure from above, compressed and hardened this peat into a sedimentary rock that differed from other rocks in one basic respect: Because of its carbon content, when dry it was capable of igniting and burning freely. Through this haphazard process, the force of nature first created coal, 200 million years before the first humans appeared. (In theory, at least, if the earth’s untapped coal reserves were left untouched for hundreds of millions more years, the Earth’s pressure would eventually convert all of it into diamonds.)

Of course Tom Purdom is right: The quality of the world’s population matters more than the quantity. That was precisely the point I was trying to make to population doomsayers in the first place. And of course we should never be smug about population growth. But then, we should never be smug about anything— including the notion that people are a drag on the planet. What Winston Churchill said about democrcy applies to people as well: We humans are the world's worst resource, except for all the other resources.

To read my previous columns on population growth, click here and here.