For centuries, men have believed that rising wealth and population would soon deplete all available resources, causing mass death and social collapse. For centuries, they have been wrong. Predictions of imminent collapse have been a constant since Thomas Malthus, who published An Essay on the Principle of Population in 1798. Malthus claimed that lowering birth rates would help prevent, or at least mitigate, this mass famine and suffering. His heirs say the same thing today. Today there are eight people for every man, woman, and child alive in Malthus’s day, and the eight eat better than the one. The days have passed when a bad winter in Europe or a megaflood on the Yellow River would cause starvation deaths by the hundred thousand. Now even the worst backwaters fear only “food insecurity” and fractional chances of stunted growth.

Claims of resource depletion and collapse have accompanied industrial society on every step from steamboats to container ships, from hot air balloons to Mars rovers. Of the many such arguments that have been put forward in our long history, the best was made in 1865, when William Stanley Jevons published The Coal Question. This book argued that industrial society was eventually doomed because of the limited supply of coal for power. Because consumption grows exponentially and supply is finite, we will eventually run out of coal and be unable to power our machines.

It’s true that the supply of coal is finite. What Jevons missed, understandably in his own time, is that coal is not the only possible source of industrial power. When he published, effectively all industrial power came from coal. In 2023, this was down to 26%. John D. Rockefeller founded Standard Oil, the first oil-producing megacorporation, five years after Jevons finished his book. A century after Jevons’s argument, in the 1960s, oil finally surpassed coal as the world’s top power source. Today coal, oil, and methane gas each provide about a quarter of the world’s power, with coal providing a bit more power than methane gas and a bit less than oil.

Peak Energy is Far in the Future

After World War II, as oil power approached and overtook coal power, the world saw similar predictions for the imminent arrival of “peak oil,” the forecasted point when oil production reaches its maximum and begins to decline. These prognosticators were more reckless and aggressive than Malthus or Jevons, in part because their motives were more ideological, and predicted that peak oil would arrive very soon, in some cases as early as the 1960s. This was bound up with the anti-industrial turn of the environmentalist movement, and rising activism for the dismantling of industrial society, which has since been euphemized as “degrowth.” Among the profusion of warnings from academics and activists, the most influential was 1972’s The Limits To Growth, which argued that exponential growth in resource demands would exceed the world’s possible supply while exponentially increasing pollution would destroy the biosphere, together causing “a rather sudden and uncontrollable decline in both population and industrial capacity.”

Since then, oil and coal production have both increased over time, sometimes with decade-long plateaus or minor dips, in defiance of these “peak” forecasts. There are two main reasons that the 20th century models and computer simulations underestimated production, even when they were done in good faith. The first is the ongoing discovery of new deposits. The Earth is incredibly, incredibly huge, and we are nowhere close to finding all of the stuff we can use. In May 2024, a Russian survey reported the discovery of Antarctic oil fields with estimated reserves of over 500 billion barrels. If these early estimates survive deeper investigation, it would be by far the largest oil discovery ever, three to five times bigger than Saudi Arabia’s world-record Ghawar field. “There are more things in … earth, Horatio, than are dreamt of in your philosophy.”

The other factor is that new technologies periodically turn useless rocks into economically valuable resources. The development of hydraulic fracturing—fracking—made it possible to extract oil from previously worthless shale, turning the U.S. from a net importer of oil to a net exporter and undercutting the economic base of rival exporters like Russia, Venezuela, and Iran. As of 2022, fracking accounted for 66% of U.S. oil production and 80% of U.S. methane gas. Earlier improvements like the invention of offshore drilling platforms had similar effects, and future technologies will no doubt continue the trend. From the 1865 vantage point of William Stanley Jevons, the 19th century technology to refine and exploit oil, or the 20th century technology to cryogenically liquify methane gas for transport and storage, also counts as turning useless rocks into new energy. It remains to be seen what advances will come in the 21st century, or the 22nd, or the 23rd.

Of course, none of this changes the fundamental logic of Jevons’s argument, it only pushes the timelines around. However gigantic the deposits of fossil fuels may be, they are still finite. If future technologies increase accessible reserves by a factor of ten, or a thousand, or a million, the underlying point remains the same: if exponential growth continues, it will use these deposits, not necessarily on the timescale of an individual person’s life, but certainly on the timescale of civilizations.

If fossil fuels were the only source of energy, this would be a civilization-shaking concern. Fortunately, they are not. In principle fission power, fusion power, geothermal power, and solar power are all capable, individually, of powering an industrial civilization far larger than our own for far longer than recorded history has lasted—billions of years, in the case of solar power. Decade by decade, the share of power from non-fossil power sources is growing at a rate roughly comparable to oil’s slow growth to eventually overtake coal. Of these sources, only fission power is yet developed enough that it could actually bear the weight of industrial civilization with our present technology. That alone is sufficient to knock down Jevons’s argument.

Geothermal or solar power might plausibly reach this point within our lifetimes, depending on advances in drilling and battery technology, respectively. Such swift success is far from certain, but if exponential growth continues and there is no interruption from civilizational collapse, then it seems very likely within a century or two, at most. Fusion power is more speculative and I’m hesitant to rely on breakthroughs in a technology where success has supposedly been right around the corner since before I was born, but who knows. We also shouldn’t discount the possibility that entirely new forms of power will someday be invented using scientific breakthroughs inconceivable to us today—after all, Jevons published not just before the creation of nuclear power plants, but before the discovery of radioactivity. None of these hypothetical advances are strictly necessary, however, since fission power with present technology is more than enough to fuel industrial civilization’s growth far past the point that anyone can forecast in any but the broadest strokes.

We Won’t Run Out of Food or Metals

More rarely, we see similar depletionist arguments for limits on durable metals like iron or aluminum. These are somewhat less dire, because if we did run out, then the possibility of recycling means this would merely prevent civilization from growing further rather than necessitate a collapse. The Limits To Growth used exponential models of resource consumption to illustrate scenarios where aluminum supplies ran out in 2003 and copper supplies ran out in 1993. Obviously this did not happen. Production of both metals has continued to increase.

Prospectors have not searched anywhere close to the entire globe and estimates of the world’s total reserves are revised upwards decade by decade. Prospecting for ores like bauxite or chalcocite which make people’s eyes glaze over is far less thorough even than prospecting for oil deposits which make corporations salivate and politicians sweat. Technological improvements regularly make more deposits accessible, whether directly by improving the economics of digging, or indirectly by allowing ores with lower and lower concentrations of metals like copper to be processed. This is not a new phenomenon. As T. A. Rickard recounts in the first volume of his 1932 magnum opus Man and Metals, p. 447, in the early 1900s slag heaps from ancient Roman lead mines were reprocessed “on a large scale” to extract metal the original miners had been unable to separate from the rock.

In principle, the limits are set by our ability to dig. The deepest mine ever dug is a gold mine 4 kilometers deep. If we could exploit all the matter within 4 kilometers of the surface—we can’t, yet—that would only amount to about one five-hundredth of the Earth’s volume. If mining technology continues to improve over the next centuries at about the same rate as the previous centuries, much much more of the Earth’s matter will come within our reach. Mining technology has long been a great stimulant to technology and growth. The world’s first useful steam engines were developed to pump water out of 0.05-kilometer-deep mines for coal and copper, making them possible to operate without flooding.

Improvements in materials technology also allow greater and greater substitutability of different resources. Within Elon Musk’s industrial empire alone, there are major efforts underway to use steel for rockets that once used only titanium, and aluminum for cars that once used only steel. Plastics and ceramics now serve many purposes which could once be fulfilled only by metals. Progress on this has been steady for centuries, and we are nowhere close to the limits imposed by the laws of physics and the structure of atoms.

The last major limit to growth is food production. Famously, this was the subject of Malthus’s warning in 1798. In 1968, Paul Ehrlich’s The Population Bomb predicted overpopulation would outpace food production and cause hundreds of millions of deaths from famine as early as the 1970s. This did not happen, although the fear it engendered prompted many governments and many individual families to reduce the number of children born. With decline in global fertility, this has become less of a concern among intellectual elites, with some early voices even worrying about population decline. The world’s population has fallen and risen many times in history. On the scale of centuries it will presumably fall again, and rise again, and so on, and the global population’s long-term upward trend will continue. Food will remain a necessity regardless.

The Limits To Growth makes much of the finite quantity of arable land as the reason that Malthusian mass starvation is inevitable. Technically this “limit” has been broken many times, from Bronze Age irrigation channels on the Nile River, to Iron Age dikes on the Yellow River, to medieval land reclamation works in the Netherlands, to today’s desalination plants in Israel. However, on a global scale, increases in arable acreage from projects like these have been relatively small. Much, much more significant have been increases in yield per acre, especially since the “Agricultural Revolution” began in 17th century Britain.

This exponential trend has continued steadily for centuries, thanks to improvements as diverse as the tractor, the Haber-Bosch process for mass-producing nitrogen fertilizer, the breeding of superior crops and livestock, pesticides, advances in soil science, and countless others. The improvements in efficiency show no signs of stopping. Since The Limits To Growth was published in 1972, the average yield per acre of most staple crops has roughly doubled, and the world’s population has increased by about the same fraction. As a result, the amount of land needed to feed the world’s growing population has stayed nearly the same. There is no particular reason to expect this trend will abruptly stop any time in the next few centuries. In 2200, the total amount of land needed to feed the world’s presumably higher population is as likely to be smaller than today as it is greater.

Reaching Towards the Limits of the Solar System

There must exist some maximum point of development that the Earth can sustain. We can imagine a civilization so advanced that they can mine every atom of uranium down to the Earth’s core, and capture every photon that strikes the planet, and convert it all to useful power with the unattainably perfect efficiency of a Carnot engine. This would be a civilization so inconceivably vast that, in comparison, we might as well be a pack of chimpanzees using grass to fish for termites. But logically, they would still be finite.

Equally logically, a civilization anywhere near that advanced would not be limited to the Earth. With a fraction of that knowledge and matter and energy, they would have no trouble settling on other planets, or mining asteroids, or building orbital solar-power arrays. Even our own civilization can already make fumbling, uneconomical attempts at these projects for scientific purposes, and the usual course of technological growth is that fumbling, uneconomical prototypes eventually become load-bearing industrial foundations, even if it sometimes takes centuries of development. The basic proofs of concept were mostly deployed in the 20th century, and have slowly improved since then. The exact course cannot be plotted, but the general direction seems clear.

When we look at spaceflight, we are in roughly the same position as Ben Franklin when he observed the early tests of hot air balloons in the 1780s, and understood vaguely but accurately that developments in flight would revolutionize warfare and “give a new turn to human affairs.” Eventually, perhaps the speculative spaceborne megaprojects like O’Neill cylinders will prove practical, or perhaps it will take a very different form. The Earth accounts for only about 0.2% of the matter orbiting the Sun and receives less than a billionth of the Sun’s energy. A sufficiently advanced civilization would end up in space somehow, because that’s where all the good stuff is.

The dream, of course, is to settle not just our own solar system, but to reach other stars. This seems much more doubtful. Sending ships to other stars is possible, in the sense that it is permitted by the laws of physics. Whether such a complex machine and its payload can be maintained on a journey of lightyears, with nothing except the mass and energy it brings along, is a tougher question. Unlike interplanetary travel, where our probes have already begun blazing the trail and men have already walked on the Moon, interstellar travel is nowhere close to anything that humans have ever done. Science fiction authors have dreamed up possibilities, but nothing that even vaguely resembles their precursors has ever been built. Perhaps future technology will solve these problems, presumably with methods that no one has yet thought of. Perhaps the challenges will prove impractical even to an ultra-advanced interplanetary civilization, as their prototypes encounter new difficulties unknown to us. If we someday figure it out and cross the chasms between stars, then we may eventually be able to cross the chasms between galaxies—a million times further—or we may not. It is far too early to say anything with confidence about such speculative technology.

Even if we can be confident that an interplanetary civilization, at least, is permitted by the resources available to us, none of this means that humanity inevitably will reach these heights. If the limits of Nature do not stop us, we might do it ourselves. Improvements in economic technology go hand-in-hand with improvements in weapons technology. Current nuclear arsenals are probably not enough to destroy industrial civilization, especially since they have shrunk fivefold with the end of the Cold War, and it is even less likely that they could end humanity itself. Fears of nuclear winter are generally overblown. Still, I would rather not try the experiment.

More recently, fears have risen of more exotic technologies like bioweapons or recursively self-improving artificial intelligence. Personally I’m more worried about the presently-inconceivable superweapons that will be developed after another century or two of technological advancement, far beyond our own imagination as the nuclear bomb was beyond Jevons. Mankind has worried about our capacity to destroy ourselves ever since the widespread use of the machine gun in World War I, and regardless of the specifics of any particular technology, we remain no closer to finding a solution while our power continues to grow.

Separately, it is entirely possible that humanity will simply choose not to leave the nest, at least for a time. Civilization after civilization has achieved several centuries of growth and scientific advance, and then petered out. At its height, classical Greco-Roman civilization made advanced prototypes like the Antikythera mechanism or the aeolipile, but by the time barbarians were pouring across the borders and carving out their kingdoms, these had vanished entirely—and more prosaically, yet more importantly, large-scale mining and water-powered mills vanished from Europe for centuries.

The stunning technological and industrial growth of China’s Tang and Song dynasties was eventually succeeded by the legendary stagnation of the Ming and Qing dynasties, famously illustrated by the decommissioning of Zheng He’s fleet in the 1430s. Our own civilization’s rate of advance remains substantial, but it has slowed down somewhat since its most frenetic pace in the days of Henry Bessemer, Thomas Edison, Henry Ford, Fritz Haber, and the Wright Brothers. Sooner or later, we will go the way of the Romans, whether that takes seventy years or two hundred and fifty. When it happens, it could delay mankind’s advance by a few centuries, unless and until a new civilization arises and picks up the torch.

Mankind’s trajectory depends on us, here, today. Every generation must build the society they want out of the parts left to them by their forebears. If we dismantle our engine of progress out of innumerate fears of resource shortages, or destroy it as we fight out internal resentments, or overburden it with a host of corrupt idlers and apparatchiks, or let it lapse out of mere sloth, then the advances of recent centuries will slow to a crawl. If we build a robust and dynamic society, if we repair and rejuvenate our institutions, then we will take the next step on the journey to set our grandchildren walking on other worlds.