We may not live in the best of all possible worlds, but we have dodged some bullets:
In the annals of environmental history, humanity’s response to the ozone crisis stands out as a rare success story. During the 1970s and ‘80s, evidence started to mount that certain household chemicals used in refrigerators, air conditioners, and aerosol cans like hairspray were eating a giant hole in Earth’s ozone layer, which prevents harmful ultraviolet radiation from reaching the surface. Facing the terrifying prospect of a future without any atmospheric sunscreen at all, in the late 1980s nations came together to sign the Montreal Protocol, a global treaty to phase out so-called ozone-depleting substances like chlorofluorocarbons.
But if things hadn’t turned out that way—if the scientific evidence linking man-made chemicals to ozone depletion wasn’t strong enough, or if ozone deniers (yes, there were ozone deniers) successfully stymied the Montreal Protocol—the world might look very different.