Stephen Campbell Moore reads Ben Rawlence's unflinching account of what the North's moving treeline will mean for humanity.

The trees are on the move. They shouldn't be. More than the Amazon rainforest, the northern boreal is truly the lung of the world. Covering one fifth of the globe and containing one third of all the trees on earth, it has been foundational to our climate for the last few million years. But now the northern forest is marching towards to the North Pole, turning the white Arctic green. And scientists are only just beginning to understand what this might mean for life on earth.

In Scotland, Scandinavia, Siberia, Canada and Greenland, Rawlence discovers what the trees and the people who live and work alongside them have to tell us about the past, present and future of our planet. At the treeline he sees the devastating and accelerating impact of climate change, but also some reasons for hope.

Today: Rawlence travels to Norway's rugged coastline, in search of birch and the reindeer herders of the north.

Writer: Ben Rawlence
Abridger: Richard Hamilton
Reader: Stephen Campbell Moore
Producer: Justine Willett Show less