Journey to the 'doomsday' glacier
Glaciologists have described Thwaites Glacier as the "most important" glacier in the world, the "riskiest" glacier, even the "doomsday" glacier.
A team of 40 or so scientists are part of the International Thwaites Glacier Collaboration, a five-year, $50m (£38m) joint UK-US effort to understand why it is changing so rapidly.
The project represents the biggest and most complex scientific field programme in Antarctic history.
The BBC's chief environment correspondent Justin Rowlatt went to meet the scientists behind the project.
Read more: Journey to the 'doomsday' glacier