Is Thwaites really a "Doomsday Glacier"?

Thwaites is not a doomsday glacier in the sense of an imminent catastrophe, and many of the scientists who study it say the nickname is misleading. But it is a real concern, because its retreat could help unlock the rest of the West Antarctic Ice Sheet and shape sea level over the coming centuries.

Thwaites sits in West Antarctica. At 120 kilometres wide it is the widest glacier in the world, and its fastest ice moves at more than 2 kilometres a year. It was named in 1967 after Fredrik Thwaites, a glacial geologist at the University of Wisconsin–Madison who had never visited it.

The worry comes from where it lies. Radar flights in the 1960s and 1970s showed that the bed under this part of West Antarctica slopes downward and lies well below sea level, and powerful ocean currents reach it. Since the 1980s, Thwaites and its neighbour Pine Island Glacier have been called the "weak underbelly" of the West Antarctic Ice Sheet, because if they retreat, the rest of the ice sheet is likely to follow in the end.

The numbers help keep this in proportion. Between 1992 and 2017, Thwaites lost over 600 billion tonnes of ice, about 4 percent of global sea level rise in that period. The amount lost this century is likely to be only several centimetres of sea level. Its breakdown would speed up in the 22nd and 23rd centuries, and all of its ice could ultimately add 65 centimetres, more than twice all the sea level rise to date.

The nickname Doomsday Glacier first appeared in a 2017 magazine article. Leading researchers including Ted Scambos, Eric Rignot, Helen Fricker and Robert Larter have criticised it as alarmist and inaccurate. Behind the label sit real measurements, and an international research collaboration founded in 2017 is studying the glacier up close.