Last month, something old became new again. What’s new is that the world population crossed the eight-billion mark for the first time. What’s old is that, for more than two centuries, experts have been warning that we’re headed for calamity because our population is unsustainable.
When, in 1798, the world population crossed the one-billion mark, economist Thomas Malthus warned that the combination of linear growth in food production and exponential growth in population put us on a path to inevitable famine. Malthus’ warning was understandable. It took humans around 250,000 years to reach a population of one-half billion, and only another 200 years to add a second half-billion. That’s like a car taking four seconds to go from zero to 60, and then three-thousandths of a second to go from 60 to 120. Malthus was quite reasonable in his prediction that the world population was headed for an ugly crash.
The reality turned out to be worse than Malthus predicted. It took 200 years for the world population to double to the one-billion of Malthus’ time. It took only 120 years for it to double again to two-billion in 1927. It took 47 years to double again to four-billion in 1974. Malthus would have regarded today’s eight-billion as, at best, impossible, and at worst, apocalyptic. Actual world population growth has been far worse than Malthus could have imagined.
But the reality is also better than Malthus imagined. Not only did food production grow geometrically, it grew even faster than the population, so that the world can feed today’s eight-billion far more easily than it could feed Malthus’ one-billion. Yet, for two centuries, experts have repeated Malthus’ error by predicting the end of the world every time the population approaches another round number.
The Malthusians’ errors lay in not understanding resources.
Resources, experts warn, are limited. That’s not entirely correct. Specific resources are limited. There’s only so much oil. There’s only so much land. There’s only so much fresh water. But resources, in general, are not limited. Or, rather, they are limited only by human ingenuity. Millenia ago, the work a person could do was limited by his stamina and the strength of his muscles. Then some enterprising humans domesticated the horse and ox, and one person, leading a team of animals, could do the work of several people. Then humans invented steam power, and one person could do the work of several teams of animals. Then humans invented the internal combustion and electric engines, and work capacity multiplied again.
With computers and machines, a single farmer today can feed around ten times the number of people as a single farmer in 1940. And human ingenuity has not just made humans more productive. It has made the land more productive also. In 1960, worldwide, a hectare of land produced around 1.3 tonnes of cereals per year. Today, a hectare of land produces more than 4 tonnes.
In the 1400s, the world derived half of its energy from work animals and the other half from burning wood. Then humans discovered how to mine and transport large quantities of coal, an energy source with a 50 percent higher energy density than wood. By the early 1900s, more than half of the world’s energy came from coal. Then humans discovered how to drill for oil – a substance with an 80 percent higher energy density than coal. By the close of the twentieth century, oil had replaced coal as the primary energy source. Humans learned how to build pipelines and distribute natural gas, a substance with a 25 percent higher energy density than oil. Today, natural gas and oil together provide half of our energy needs. Within the next century, humans will learn how to harness nuclear fusion, and that will make energy virtually limitless and almost free.
Malthus was wrong because he believed that our ability to feed ourselves depended on natural resources. Natural resources do matter, but ultimately, they aren’t what feed us. Human ingenuity is what feeds us. Earth provides materials, but it’s human ingenuity that turns those materials into valuable resources. And so long as there is human ingenuity, there will always be resources.
And this brings us to what we might call the “Malthusian contradiction.” Only a small minority of humans have the intelligence, skill, drive, and luck to invent and discover new resources. To ensure that we have enough of these rare humans to keep invention and discovery going, we need more humans. If only one in a thousand of us is a genius, and only one in one-hundred of those has the outsized drive to search for new discoveries or create new inventions, and only one in ten of those has the luck that so often plays a role in discovery, then we’d need a population of one million to expect to get just a single Thomas Edison or George Washington Carver or Steve Jobs. And what if we needed thousands, or tens of thousands, of Edisons? We’d need a population well into the billions.
A second thing that Malthusians (the old and the modern) fail to appreciate is that complex systems are self-correcting. As the number of people grows, not only do we have more of those rare ingenious humans, but increased demand for specific resources drives prices of those resources up, and elevated prices summon armies of people to seek out, establish, finance, and assist those geniuses. Behind every Jeff Bezos are thousands of entrepreneurs, investors, consumers, and workers putting their own particular talents and treasures to work, also. The result is that exponential population growth necessarily gives rise to exponential resource growth.
The common counterargument is that, while we have managed to feed ourselves, the Earth’s environment is groaning under our collective weight. And yet here, again, the evidence points to ingenious humans saving the day. Since 1990, worldwide deaths due to air pollution are down 45 percent on a per-capita basis. Since 1990, deforestation in developed countries has reversed course and become reforestation. While deforestation continues in developing countries, the rate is slowing and shows every sign of turning around to reforestation within the next several decades. In 2000, 60 percent of the world’s people had access to safe drinking water. Today, it’s almost 75 percent and projected to rise above 80 percent by the end of the decade. Carbon emissions in the US peaked in the 2000s and are now down 30 percent. Carbon emissions worldwide are down 5 percent in 2020 versus 2019, and the major carbon emitters (China and the rest of Asia) are steadily slowing their emissions.
Malthusians err in thinking that resources are limited and that the key to saving humanity is to limit our consumption of those resources by limiting our numbers. The truth is that it’s humans who create resources in the first place. When Malthusians point to explosive population growth, they think they are identifying a problem. They are actually identifying the solution.