But Christianson and his colleagues were not just ice geeks mapping the hidden topography of the planet. They were mapping a future global disaster. As the world warms, determining exactly how quickly ice melts and seas rise may be one of the most important questions of our time. Half the world’s population lives within 50 miles of a coastline. Trillions of dollars of real estate is perched on beaches and clustered in low-lying cities like Miami and New York. A long, slow rise of the waters in the coming decades may be manageable. A more abrupt rise would not be. “If there is going to be a climate catastrophe,” says Ohio State glaciologist Ian Howat, “it’s probably going to start at Thwaites.”

The decade that just ended was by far the hottest ever measured on Earth, capped off by the second-warmest year on record, two U.S. agencies reported Wednesday. And scientists said they see no end to the way man-made climate change keeps shattering records.

That was was the first line of David Wallace-Wells’s horrifying 2017 essay in New York magazine about climate change. It was an attempt to paint a very real picture of our not-too-distant future, a future filled with famines, political chaos, economic collapse, fierce resource competition, and a sun that “cooks us.”

Wallace-Wells has since developed his terrifying essay into an even more terrifying book, titled The Uninhabitable Earth: Life After Warming. And it is a brutal read. Wallace-Wells was criticized in 2017 for being too hyperbolic, too doom-and-gloomy. But as Vox’s David Roberts explained at the time, those criticisms were mostly misplaced.

Wallace-Wells isn’t counseling despair or saying all is lost; he’s merely laying out the alarming facts of what is likely to happen if we don’t radically change course.