The information presented here cannot be used directly to calculate Earth's long-term carrying capacity for human beings because, among other things, carrying capacity depends on both the affluence of the population being supported and the technologies supporting it. – Paul Ehrlich, 1986
One would expect scientists to pause when they realize their argument about resource collapse makes the king of environmental catastrophe, Paul Ehrlich, look moderate by comparison. Ehrlich is best known for a 40-year series of wildly inaccurate predictions of looming environmental disaster. Yet he looks positively reasonable compared to a paper recently published in the scientific journal Nature titled “Approaching a state shift in Earth’s biosphere.”
The paper predicts we are rapidly approaching a moment of “planetary-scale critical transition,” due to overuse of resources, climate change and other human-caused environmental damage. As a result, the authors conclude, this will “require reducing world population growth and per-capita resource use; rapidly increasing the proportion of the world’s energy budget that is supplied by sources other than fossil fuels,” and a range of other drastic policies. If these sound much like the ideas proposed in the 1970s by Ehrlich and others, like The Club of Rome, it is not a coincidence. The Nature paper is built on Ehrlich’s assumptions and cites his work more than once.
The Nature article, however, suffers from numerous simple statistical errors and assumptions rather than evidence. Its authors do nothing to deal with the fundamental mistakes that led Ehrlich and others like him down the wrong path so many times. Instead, the paper simply argues that with improved data, this time their predictions of doom are correct.
Ultimately, the piece is a good example of the great philosopher of science Thomas Kuhn’s hypothesis, written 50 years ago, that scientists often attempt to fit the data to conform to their particular scientific paradigm, even when that paradigm is obviously flawed. When confronted with failure to explain real-world phenomena, the authors of the Nature piece have, as Kuhn described in The Structure of Scientific Revolutions, devised “numerous articulations and ad hoc modifications of their theory in order to eliminate any apparent conflict.” Like scientists blindly devoted to a failed paradigm, the Nature piece simply tries to force new data to fit a flawed concept.
“Assuming this does not change”
During the last half-century, the world has witnessed a dramatic increase in food production. According to the U.N.’s Food and Agriculture Organization, yields per acre of rice have more than doubled, corn yields are more than one-and-a-half times larger than 50 years ago, and wheat yields have almost tripled. As a result, even as human population has increased, worldwide hunger has declined.
Despite these well-known statistics, the authors of the Nature study assume not only no future technological improvements, but that none have occurred over the last 200 years. The authors simply choose one data point and then project it both into the past and into the future. The authors explain the assumption that underlies their thesis in the caption to a graphic showing the Earth approaching environmental saturation. They write:
“The percentages of such transformed lands... when divided by 7,000,000,000 (the present global human population) yield a value of approximately 2.27 acres (0.92 ha) of transformed land for each person. That value was used to estimate the amount of transformed land that probably existed in the years 1800, 1900 and 1950, and which would exist in 2025 and 2045 assuming conservative population growth and that resource use does not become any more efficient.” (emphasis added)
In other words, the basis for their argument ignores the easily accessible data from the last half century. They take a snapshot in time and mistake it for a historical trend. In contrast to their claim of no change in the efficient use of resources, it would be difficult to find a time period in the last millennium when resource use did not become more efficient.
Ironically, this is the very error Ehrlich warns against in his 1986 paper – a paper the authors themselves cite several times. Despite Ehrlich’s admonition that projections of future carrying capacity are dependent upon technological change, the authors of the Nature article ignore history to come to their desired conclusion.
A Paradigm of Catastrophe
What would lead scientists to make such simplistic assumptions and flat-line projections? Indeed, what would lead Nature editors to print an article whose statistical underpinnings are so flawed? The simple belief in the paradigm of inevitable environmental catastrophe: humans are doing irreparable damage to the Earth and every bit of resource use moves us closer to that catastrophe. The catastrophe paradigm argues a simple model that eventually we will run out of space and resources, and determining the date of ultimate doom is a simple matter of doing the math.
Believing in this paradigm also justifies exaggeration in order to stave off the serious consequences of collapse. Thus, they describe the United Nations’ likely population estimate for 2050 as “the most conservative,” without explaining why. They claim “rapid climate change shows no signs of slowing” without providing a source citation for the claim, and despite an actual slowing of climate change over the last decade.
The need to avoid perceived global catastrophe also encourages the authors to blow past warning signs that their analysis is not built on solid foundations – as if the poor history of such projections were not already warning enough. Even as they admit the interactions “between overlapping complex systems, however, are providing difficult to characterize mathematically,” they base their conclusions on the simplest linear mathematical estimate that assumes nothing will change except population over the next 40 years. They then draw a straight line, literally, from today to the environmental tipping point.
Why is such an unscientific approach allowed to pass for science in a respected international journal? Because whatever the argument does not supply, the paradigm conveniently fills in. Even if the math isn’t reliable and there are obvious counterarguments, “everyone” understands and believes in the underlying truth – we are nearing the limits of the planet’s ability to support life. In this way the conclusion is not proven but assumed, making the supporting argument an impenetrable tautology.
Such a circumstance creates the conditions of scientific revolutions, where the old paradigm fails to explain real-world phenomena and is replaced by an alternative. Given the record of failure of the paradigm of resource catastrophe, dating back to the 1970s, one would hope we are moving toward such a change. Unfortunately, Nature and the authors of the piece are clinging to the old resource-depletion model, simply trying to re-work the numbers.
Let us hope policymakers recognize the failure of that paradigm before they make costly and dangerous policy mistakes that impoverish billions in the name of false scientific assumptions.