Fifty years ago, shortly after we arrived in Pennsylvania from Europe, I came across D’Arcy Wentworth Thompson’s classic On Growth and Form (originally published in 1917, with a revised edition published in 1942), which looks at the role of mathematics in biology. I almost immediately thought about writing a similarly systematic book someday that would go beyond organisms and look also at the evolution of growth trajectories in human artifacts (from simple tools to complex machines) and complex systems (from populations to economies).
Now I have finally done it. Growth: From Microorganisms to Megacities appraises our understanding of that ubiquitous reality encompassing both the diffusion of viral infections and the expansion of empires. This vast realm includes multitudes of fascinating phenomena ranging from the indefinite growth of giant trees to inverse power ranking of cities. All of these appear to be just matters of academic interest, however, when compared with the most consequential growth-related concern affecting our civilization: the contrast between the dominant model of economic progress and the need to preserve a habitable biosphere.
No phenomenon defining modern civilization has been more important and more pervasive than growth, and the seven post-1950 decades have seen an extraordinary concatenation of advances. On the global level, population has nearly tripled, harvests of staple grains have more than quadrupled, the consumption of energy has increased nearly sevenfold (and electricity generation is now nearly 30 times higher than it was) and the world uses nearly 10 times as much steel and more than 30 times as much nitrogen fertilizer. As a result, worldwide economic output is now more than 12 times higher than it was in 1950.
This growth has been translated into many welcome personal gains. Since 1950 the average global life expectancy at birth has increased by about 50 percent to more than 72 years, while the share of malnourished people has been reduced from more than 40 percent to less than 10 percent of the world’s population. The average global per capita GDP has more than quadrupled, and an increase in the average size of everything from American houses (2.5 times bigger than in 1950) to European cars (more than doubled over that time) has become a common experience during a single lifetime.
By far the greatest increases have been associated with travel and communication. Worldwide, flying (measured in passenger-kilometers per year) is now about 250 times more common, and at about 50 zettabytes (5 × 1021 bytes) the total amount of information generated per year is now two orders of magnitude higher than it was just two decades ago.
The obverse of this growth—anthropogenic changes and degradation of the biosphere—has reached an unprecedented intensity and extent. No major biome has escaped extensive destruction or modification by human activities; the decline of global biodiversity has been proceeding at rates that, on geological time scales, may already amount to the Earth’s sixth mass extinction; many densely populated regions have seen reduced availability and reliability of water supply; and oceans and their biota have been affected by things such as massive accumulations of microplastics and coastal eutrophication.
Concerns about these changes have been either intensified or overshadowed by worries about the impact of anthropogenic warming. Since 1950, carbon dioxide emissions from fossil fuel combustion, considered as tropospheric concentrations of the gas, have risen from less than 320 to more than 410 parts per million in 2018.
Moderating and eventually reversing this trend would require replacing the dominant source of energy with noncarbon alternatives, and if the goal were to limit global warming to an average temperature increase of less than two degrees Celsius, it would have to be done in a matter of decades—an unprecedented transition that would transform all aspects of modern civilization. And yet, in stark contrast to this now widely accepted conclusion, there are no expectations of an early end to energy, material and economic growth.
Forecasts by international organizations see the demand for oil and gas rising at least until 2040 (when coal would still be the dominant fuel in electricity generation). World economic output could be three times the current amount in 2060, and worldwide passenger-kilometers of travel are expected to more than triple by 2040. Assumptions of continued growth prevail even in the largest mature, affluent economy, with the American GDP forecast to double by 2060.
And despite the ubiquitous talk about sustainability, green economies and decarbonization, no nation has any thoughtful, deliberate long-term plans or policies that would lead to substantial slowdowns in the growth of energy, materials and economic output. Instead we are promised that future economic growth will be decoupled from energy and material consumption.
Relative decoupling—that is, reductions in energy intensity and in the material requirements of individual products or entire economies—has been essential to modern development, and it will continue. But absolute decoupling of economic growth from energy and materials on the global level (that is, their uses steadily declining as economic output keeps rising) contradicts physical laws: basic existential needs for the approximately two billion people who will be born by 2050 alone will demand substantially increased energy and material inputs.
Moreover, the complete global decarbonization of energy use cannot be accomplished in just a decade or two because of the large mass and dominance of carbon-based fossil fuels (about 10 billon metric tons a year are used now, supplying 85 percent of global primary energy use and because of the lack of readily available alternatives that could be deployed on the requisite scales and at affordable cost. How can we replace the fuels that heat the households of one billion people in cold climates? How can we replace the more than half a billion metric tons of refined fuels used in ocean and air transportation? What will substitute for the nearly one billion metric tons of fossil fuels destined for non-energy uses—above all for the synthesis of ammonia and plastics? How can we eliminate more than half a billion metric tons of coke used in iron-smelting blast furnaces?
If the consensus climate models are right, then maintaining the past rates and modes of global economic growth is incompatible with staying within tolerable temperature limits through 2050—but we have no realistic plans to do away with incessant growth.
In any case, rapid and drastic departures from those practices are not possible with our current technical capabilities, and they would only worsen existing global inequalities. I never make forecasts, but I wish I could be around in 2050 to see how the global civilization resolves this existential dilemma—or how it fails.