Robert Macfarlane, bestselling author, walker, mountaineer and campaigner, talks to Kirsty Lang

Robert Macfarlane walks into the mountains, along ancient paths and down into caves and potholes. He has written beautiful and popular books about these - Mountains of the Mind, The Old Ways, Underland. He is concerned about the depletion of the natural world, and the language we use to speak of it. Landmarks is a lexicon of landscape and nature. When a new edition of a famous children's dictionary left out several common nature words - bluebell, conker, kingfisher - he wrote a series of poems, spells to bring them back to use, and with the artist Jackie Morris created a book. The Lost Words: A Spell Book found its way into half the primary schools in England, and every one in Scotland, and has had a profound impact on the education of children about nature. He worked with several musicians, who set the spells to create an album.

Macfarlane is also a campaigner: moved by the felling of trees in Sheffield, and the protests against this, he gave a poem for anyone to use in protests. It has been translated into Telegu and used in India, as well as at HS2 demonstrations.

Now Macfarlane is working with the actor and singer Johnny Flynn, writing songs inspired by the oldest known written story, Gilgamesh. In this Gilgamesh takes an axe to a scared cedar grove in the first act of deforestation. In the month when Donald Trump has finalized plans to allow drilling for oil and gas in the Arctic Wildlife Refuge, the earliest story, Macfarlane explains, speaks across 4,000 year to us today.

Macfarlane talks to Kirsty Lang about books, collaborations and work in progress. He is deeply concerned about our treatment of the natural world, but his writing is charged with joy and, he explains, he his hopeful.

Presenter: Kirsty Lang Producer: Julian May