Thwaites Glacier is an unusually broad and vast Antarctic glacier located east of Mount Murphy, on the Walgreen Coast of Marie Byrd Land. It was initially sighted by polar researchers in 1940, mapped in 1959–1966 and officially named in 1967, after the late American glaciologist Fredrik T. Thwaites. The glacier flows into Pine Island Bay, part of the Amundsen Sea, at surface speeds which exceed 2 kilometres (1.2 mi) per year near its grounding line. Its fastest-flowing grounded ice is centered between 50 and 100 kilometres (31 and 62 mi) east of Mount Murphy. Like many other parts of the cryosphere, it has been adversely affected by climate change, and provides one of the more notable examples of the retreat of glaciers since 1850.
Thwaites Glacier is closely monitored for its potential to elevate sea levels. Since the 1980s, Thwaites and Pine Island Glacier have been described as part of the "weak underbelly" of the West Antarctic Ice Sheet, in part because they seem vulnerable to irreversible retreat and collapse even under relatively little warming, but mainly because if they go, the entire ice sheet is likely to eventually follow. This hypothesis is based on both theoretical studies of the stability of marine ice sheets and observations of large changes on these two glaciers. In recent years, the flow of both of these glaciers has accelerated, their surfaces have lowered, and their grounding lines have retreated. They are believed very likely to eventually collapse even without any further warming. The outsized danger Thwaites poses has led to some reporters nicknaming it the Doomsday Glacier, although this nickname is controversial among scientists.
