More than 1,000m underground is one of Britain's deepest mines. But it's not coal they're mining in North Yorkshire. It's a mineral that could help fight climate change. On this week's ClimateCast, Tom Heap explores the tunnels way beneath the North Sea bed to find out if what lies under the ground can help protect the atmosphere above. He discovers how miners are extracting polyhalite, a fertiliser that emits 85% less emissions than its counterparts, and learns why a multi-billion pound project is under way to extract more. Above ground, he's joined by professor of soil erosion and conservation, Jane Rickson from Cranfield University, to discuss the state and significance of the ground beneath our feet.Producers: Emma Rae WoodhouseEditor: Philly Beaumont