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What an 18th century treatise on population can teach us about energy resources


A several hundred year old treatise on human population offers insight into understanding energy resources.

Thomas Malthus

In 1798, a fellow by the name of Thomas Malthus predicted what he believed to be impending doom for the human race. By his calculations, the human race was outpacing its ability to produce food for itself. Malthus, a British scholar and economist, figured that a single acre of cropland would only increase yields by some small percentage each year. Humans, on the other hand, would double their population every hundred years or so. In his treatise, “An Essay on the Principle of Population”, Malthus formalized his portent of cataclysmic famine by stating “the power of population, is so superior to the power of the earth to produce subsistence from man, that premature death must in some shape or other visit the human race.” This "premature death", by Matlhus’ reasoning, would occur midway through the 1800s.

As we know, Malthus’ prediction didn’t come true. Human kind didn’t succumb to a massive famine. From the time of his writing in 1798 to the mid-1800s, the global planet gained 100 million people, bringing the total to well over a billion people. New croplands were cultivated in the newly explored United States, rich in land and nutrients, helping to feed a growing world population.

World population increased over sixfold from 1800 through 2000.

But then something happened midway through the 20th century: population exploded. The number of people passed the 3 billion mark sometime in the 1960s, and crossed the 6 billion mark at the turn of the millennium. The reason? A new technological advance revolutionized modern agriculture: fertilizers. By pulling nitrogen out of the air in seemingly unlimited quantities, farmers could overcome the natural nutrient limitations in crop land and produce more food. No longer bound to natural limitations of agriculture, more calories could be supplied, which in turn, resulted in more people.

There are strong parallels to the growth of modern agriculture to the story of modern energy resources. New scientific and engineering advancements are challenging previously held beliefs about the world’s energy supplies. Developments such as horizontal drilling and hydraulic fracturing are unlocking previously unattainable oil and natural gas resources, essentially “feeding” a growing planet.


In the 1950s, a geologist at Shell Oil Company named M. King Hubbert proposed that humankind would run up against natural limits in terms of available oil reserves. By Hubbert’s calculations, humankind was consuming oil at a rate faster than it was being replenished by natural processes. By doing so, a peak in oil production was inevitable: the early 1970s for U.S. production, around the year 2000 for global production.

Hubbert’s peak projected that global crude oil production would peak around the turn of the millennium. Courtesy of Cornell University.

To his credit, Hubbert was essentially spot on with his U.S. estimate, which expected U.S. oil production to peak in the early 1970s and decline in following decades (coincidentally, the same holds true for Texas oil production). His estimates for a global peak, however, have not come true.

While useful at the time, if anything, to reinforce the idea of rates, Hubbert’s peak has grossly underestimated the world’s recoverable oil resources. Like Malthus before him in the 18th century, Hubbert’s estimate leaves out advancements in extraction technologies that have led to record global oil production levels, among other considerations. According to data from British Petroleum’s 2012 Statistical Review, global oil production exceed 83 million barrels per day, fueled in large part by domestic U.S. production. Most estimates expect global energy demand to continue, along with oil production (at least through the middle of this century).

Global oil production has continued to increase, aided by high demand and technological advances such as horizontal drilling and hydraulic fracturing.

At some point, however, no addition of technological advances will result in more natural oil production because of the previously mentioned timescales (which is why biofuels are particularly interesting because we can essentially fast forward millions of years of heat and pressure). We will essentially reach the top of the “S curve" for oil production, and by that time, it’s reasonable to assume that a substitute for oil will be available, which poses far more interesting questions: what will the new resources be, and what will be the triggers that initiate a shift?

As we have learned with the modern food economy, natural limits of energy resources must ultimately be respected, but so must technological advances.

The views expressed are those of the author and are not necessarily those of Scientific American.

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