Jon Gertner writes:

Few places in Antarctica are more difficult to reach than Thwaites Glacier, a Florida-sized hunk of frozen water that meets the Amundsen Sea about 800 miles west of McMurdo. Until a decade ago, barely any scientists had ever set foot there, and the glacier’s remoteness, along with its reputation for bad weather, ensured that it remained poorly understood. Yet within the small community of people who study ice for a living, Thwaites has long been the subject of dark speculation. If this mysterious glacier were to “go bad”—glaciologist-­speak for the process by which a glacier breaks down into icebergs and eventually collapses into the ocean—it might be more than a scientific curiosity. Indeed, it might be the kind of event that changes the course of civilization.

In December 2008, a Penn State scientist named Sridhar Anandakrishnan and five of his colleagues made the epic journey to Thwaites, two days from McMurdo by plane, tractor, and snowmobile. All glaciers flow, but satellites and airborne radar missions had revealed that something worrisome was happening on Thwaites: The glacier was destabilizing, dumping ever more ice into the sea. On color-coded maps of the region, its flow rate went from stable blue to raise-the-alarms red. As Anandakrishnan puts it, “Thwaites started to pop.”

The change wasn’t necessarily cause for alarm. Big glaciers can speed up or slow down for reasons that scientists still don’t completely grasp. But Anandakrishnan knew that Thwaites’ unusual characteristics—it is shaped like a wedge, with the thin front end facing the ocean—left it vulnerable to losing vast quantities of ice quickly. What’s more, its size was something to reckon with. Many glaciers resemble narrow rivers that thread through mountain valleys and move small icebergs leisurely into the sea, like a chute or slide. Thwaites, if it went bad, would behave nothing like that. “Thwaites is a terrifying glacier,” Anandakrishnan says simply. Its front end measures about 100 miles across, and its glacial basin—the thick part of the wedge, extending deep into the West Antarctic interior—runs anywhere from 3,000 to more than 4,000 feet deep. A few years before Anandakrishnan’s first expedition, scientists had begun asking whether warming waters at the front edge could be playing a part in the glacier’s sudden stirring. But he wanted to know what was going on deep below Thwaites, where its ice met the earth. [Continue reading…]