Humanity is engaged in a high-stakes race with its own growth: Lest our use of energy and materials get out of control, we must constantly innovate to become more efficient. Unfortunately, new research suggests we may be losing.
The rapid advancement of electronics technology illustrates how the race works. The number of transistors in the world’s devices has gone from one in 1947 to a thousand billion today — more than there are letters in all the written text produced in human history.
The proliferation hasn’t inundated the planet because the amount of physical material and energy used in each transistor has shrunk spectacularly, reflecting a relentless advance — seen in almost all technologies — that gets economists and tech enthusiasts excited about the possibilities for a cleaner and more environmentally friendly future.
The hope is that by doing more with less, we can keep growing without bumping up against physical limits — an
optimistic vision sometimes called “decoupling.” But is there any evidence for it? That’s less clear.
Long ago, the economist William Jevons noted that improvements in energy efficiency, by reducing prices, often induce people to use still more energy. For decoupling to work, efficiency gains in energy or material must outpace this “rebound effect,” as well as other factors such as overall growth in production and population. Despite all the progress humanity has made, a new parsing of the empirical data suggests that’s not happening.
Two engineers, Christopher Magee of the Massachusetts Institute of Technology and Tessaleno Devezas of the University of Beira Interior in Portugal, looked at two sets of data covering 116 different technologies existing between 1940 and 2010, ranging from the chemical industry and electronics to metals, wood and energy. Almost every technology over this period shows exponential improvement (though at different rates) in prices, performance and efficiency of energy and material use. Over 20 years up to 2009, for example, the price of photovoltaics consistently dropped about 10 percent per year.
The improvements weren’t enough, though, to outpace the combination of population growth, economic expansion and the rebound effect. As a result, overall material use tended to increase: Those photovoltaics, for example, consumed about 13 percent more materials each year.
To be sure, the data are far from perfect. Information on many of the 116 technologies exists over intervals of only one or two decades. Still, the fact that none of the data fit the usual story of decoupling suggests that the concept is at the very least highly questionable. The only six exceptions were technologies for producing substances such as asbestos, mercury and thallium — all toxic materials that were ultimately controlled by policy intervention and legal restriction.
The results don’t imply that humans won’t ever achieve decoupling. They simply suggest that the historical record so far isn’t encouraging, and that there’s no reason to expect it to happen on its own.
Magee and Devezas, for their part, remain optimistic. We might still find a solution, they told me, if we can manage to eschew politically motivated argument and predetermined conclusions in favor of more good science and especially empirical work. The more we recognize the burden that ever- increasing materials use puts on the planet, the more we might be able to encourage forces of many kinds — market, government or spontaneous social movements — to counter the trend.