The sami

The march of the larch: the Treeline is now encroaching on the arctic tundra

Covering 20 per cent of the Earth’s surface, the boreal forest is the largest living system, or ‘biome’, on land. It contains one third of all the planet’s trees and encircles much of the northern hemisphere in a halo of green. The northernmost extent of this forest, called the treeline, marks the point beyond which it is too cold for trees to grow. This is perhaps not where you’d expect to find Ben Rawlence, an author and journalist whose previous books have focused on humanitarian crises in Africa. But, as he explains in The Treeline, things are changing alarmingly fast in this biome: ‘The trees are on the move. They