COMMENT pubs.acs.org/est
The Calculus of Unsustainability
S
ustainability is a squishy term—and difficult to operationalize for public policy. As I give talks to civic groups and students, I am often asked, “Exactly what is it that is not sustainable?” Perhaps the underlying problem is the public’s lack of understanding about material stocks and flows, integrals and derivatives, i.e., the calculus of unsustainability. In the U.S., we simply do not seem to get it. On October 31 of this year, according to the United Nations, the global population reached 7 billion (http://www.unfpa.org/ public/home/news/pid/7597). What a milestone! When I was born there were 2.5 billion people on earth, so we’ve almost trebled population in one (old) editor’s lifetime. But emissions of greenhouse gases have increased even more, greater than 6-fold since that time. That rate of change in emissions (the derivative) makes for a huge accumulation of greenhouse gases in the atmosphere as shown in the figure (Source: Scripps-NOAA, 2010). Clearly, such accumulation (the integral—area under the curve) of a radiatively important trace gas is not sustainable over the long run. It is as simple as that. The good news is that the rate of population change is decreasing, and demographers tell us we may reach a plateau around 9 billion people sometime in the middle of the 21st century. The bad news is that the plateau is likely to not be sustainable either—it depends on how we use our resources. Resource utilization (land, labor, capital) defines our economics. My favorite economist is Herman Daly, of ecological economics fame at the University of Maryland. Daly is the one who wrote A Steady State Economy (http:// www.sd-commission.org.uk/publications.php?id=775) to which no one seems to have paid much policy attention. If economics really is the “dismal science”, then environmental science must be “depressing science on a suicide watch”. Contributing to our depression is the exploitation of natural capital like nonrenewable resources. Deaccumulation (an integral of a declining supply curve) can be perilous and also UNSUSTAINABLE. The static reserve index, that is how many years remain of proven reserves at current global usage rates, is only about 64 for petroleum, 13 for indium in LCD displays, 30 for antimony in drugs, and 29 years for silver (http:// en.wikipedia.org/wiki/Oil_reserves;http://img.labnol.org/files/ how_many_years.jpg). But that does not tell the whole story because nonrenewable resource usage is not static, rather the consumption rate is usually increasing exponentially. Fortunately, we are finding more “proven reserves” and recycling, reusing, and substituting for them. But can a mining company ever be sustainable? (See answer below). Erdmann and Graedel published a fascinating review article in ES&T arguing that static reserves are not the best way to view unsustainability of metals. Rather criticality, which considers both vulnerability and risk of supplies, is more meaningful. They show that the Rare Earth Elements (REE), Platinum Group Elements (PGE), niobium, cobalt, scandium, tungsten, gallium, and antimony are probably the critical ones we should be worrying about (Erdmann and Graedel, Environ. Sci. Technol. 2011, 45, 7620 7630, dx.doi.org/10.1021/es200563g). So many precious r 2011 American Chemical Society
metals are utilized in the exploding electronic consumer products of today. For example, the computer chip industry consumed about 11 metals in 1980 and now uses 60 elements today— almost 2/3 of the natural periodic table! (Schmitz and Graedel, Environment360, 2010, http://e360.yale.edu/content/feature. msp?id=2266) Likewise, the accumulation of greenhouse gases in the atmosphere is unsustainable in the absence of substitution for fossil energy. But U.S. Presidential candidate and Texas Governor Rick Perry said in a recent debate, “The science is not settled” on human-induced global warming. It reminds me of the principal error in The Skeptical Environmentalist—where Lomborg fails to appreciate that the accumulation of greenhouse gases (and climate change) will continue unimpeded for centuries in the absence of mitigation toward preindustrial levels (The Skeptical Environmentalist, 2001, Cambridge University Press). Perry and Lomborg fail the calculus test. We have warmed the earth so much already (in the early stages) that the ocean is absorbing an immense amount of heat. If every person on earth (7 billion) ran 40 industrial strength hair dryers of 1400 W each, it would be equivalent to the warming we add to the planet each year (http://www.climatestorytellers.org/stories/james-hansen-makikosato-perceptions-of-climate-change/). The U.S. could use some more math—the calculus of unsustainability. Our future depends upon it. (Answer: Yes, a mining company can be sustainable if they continuously discover new ways to recycle and/or substitute for nonrenewable minerals and avoid nonrecoverable, dissipative uses. Europe is approaching 100% recycle of lead. When that happens, it obviates the need for more lead mining and the company evolves into a recycling enterprise rather than an extractive industry.) Jerald L. Schnoor Editor-in-Chief
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Published: December 05, 2011 10289
dx.doi.org/10.1021/es2038118 | Environ. Sci. Technol. 2011, 45, 10289–10289
