The world’s most vulnerable glacier is also one of the hardest to reach. Our knowledge of it has been hard-won through challenging journeys, but this science from the bottom of the world has a lot to tell us.

Science is a fallible, communal human process; it moves by slow self-correction, threading its way through uncertainties like a ship among icebergs. In Pine Island Bay, where the ocean charts themselves are still being updated, precision is vital. But precision takes time, and Thwaites’s time seems to dwindle with each new study.