The Uninhabitable Earth: Life After Warming

by David Wallace-Wells

You have probably heard of “coral bleaching”—that is, coral dying—in which warmer ocean waters strip reefs of the protozoa, called zooxanthellae, that provide, through photosynthesis, up to 90 percent of the energy needs of the coral. Each reef is an ecosystem as complex as a modern city, and the zooxanthellae are its food supply, the basic building block of an energy chain; when they die, the whole complex is starved with military efficiency, a city under siege or blockade. Since 2016, as much as half of Australia’s landmark Great Barrier Reef has been stripped in this way. These large-scale die-outs are called “mass bleaching events”; one unfolded, globally, from 2014 to 2017. Already, coral life has declined so much that it has created an entirely new layer in the ocean, between 30 and 150 meters below the surface, which scientists have taken to calling a “twilight zone.” According to the World Resources Institute, by 2030 ocean warming and acidification will threaten 90 percent of all reefs. This is very bad news, because reefs support as much as a quarter of all marine life and supply food and income for half a billion people. They also protect against flooding from storm surges—a function that offers value in the many billions, with reefs presently worth at least $400 million annually to Indonesia, the Philippines, Malaysia, Cuba, and Mexico—$400 million annually to each. Ocean acidification will also damage fish populations directly. Though scientists aren’t yet sur...