Danger on the mountain

John All is not only a climate scientist but also a high-level athlete, Mt. Everest-summitting climber, wilderness medic, scuba diver, and all around major badass and practitioner of what one might call extreme science — he goes with interdisciplinary teams of researchers to remote parts of the world to collect data and observe the natural world and the changes to it caused by human activities. And he trains other scientists to do this kind of work safely. His new book is Icefall: Adventures at the Wild Edges of Our Dangerous, Changing Planet, in which he talks about his adventures, including a terrifying fall 70 feet down a crevasse in the Himalayas.