Climate change is a familiar fact of life today, but it was still a new concept thirty years ago, in 1989, when Bill McKibben’s landmark The End of Nature was published. The author and activist intended the book, his first, to be a warning about the fragility of nature and an entreaty to live lightly on the earth. Among the potential environmental disasters he described was an increase in the “greenhouse effect”: Like the transparent walls of a greenhouse, certain gases in the earth’s atmosphere trap the sun’s heat. Normally this effect is benign. In fact, without it the planet would be cold and barren. But in the 1980s scientists were beginning to realize that too great an increase in “greenhouse gases” — water vapor, carbon dioxide, methane, nitrous oxide, chlorofluorocarbons, and others — would cause runaway warming.