All unsustainable activities resemble one another; each sustainable practice is sustainable in its own way.11xI wish to thank Wyatt Galusky, Laura Kolar, and Josh Yates for their feedback and discussion about earlier drafts of this essay. Those activities that cannot be sustained, alas, all succumb to the laws of thermodynamics and the very fact of organic life. They are alike in their need for resources and for inputs beyond themselves. They are not self-perpetuating. As for the sustainable options, whether they are ecological, economic, cultural, political, organizational, or moral, we have no shortage of ways to conceive of thinking in terms of keeping something going.
There is also no shortage of informed analysis of the problems of unsustainable activity. For the most part, these are commentaries on environmental health, from ecosystem integrity and public health to biodiversity, climate change, pollution, waste, and blight. A laundry list of metrics allows for these commentaries, revealing not only that the human draw from and impact on the nonhuman environment is increasing, but also that over the past century and a half the rate of increase is increasing. As Joshua Yates shows in his essay in this issue, those metrics range from GDP, carbon emissions, energy demands, and fossil fuel extraction to fertilizer use, water consumption, deforestation, and species extinction. While world population has more than tripled in the past century, water use has increased about fivefold, fertilizer consumption several hundredfold, forest and woodlands losses close to sixfold, and species extinction about twentyfold. The numbers are startling. Global expectations for how humans live on earth are insatiable.