How do you like your water – frozen or salty? In Ice Rivers, glaciologist Jemma Wadham tells the story of frozen landscapes across the globe, explaining how they are melting at an accelerating rate. In The Brilliant Abyss, Helen Scales talks about our relationship with the deep sea, how we imagine, explore and exploit it. It is the last, vast wilderness on the planet, home to fantastic creatures but also a space exploited by humans for minerals and food.

Jemma Wadham is Professor of Glaciology at University of Bristol. Helen Scales is a marine biologist, diver, broadcaster and author. Andy Fryers is Hay Festival Sustainability Director.