The Uninhabitable Earth: Life After Warming

by David Wallace-Wells

the Air Quality Index categorizes the risks according to an idiosyncratic unit scale tabulating the presence of a variety of pollutants: the warnings begin at 51–100, and at 201–300 include promises of “significant increase in respiratory effects in the general population.” The index tops out with the 301–500 range, warning of “serious aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly” and “serious risk of respiratory effects in the general population”; at that level, “everyone should avoid all outdoor exertion.” The Chinese “airpocalypse” of 2013 doubled the high end of that upper range, reaching a peak Air Quality Index of 993, and scientists studying the phenomenon suggested that China had inadvertently invented an entirely new and unstudied kind of smog, one that combined the “pea soup” pollution of industrial-era Europe and the small-particulate pollution that has lately contaminated so much of the developing world. That year, smog was responsible for 1.37 million deaths in the country.