Grass is not confined to the tropics.
It manages to grow even in the bitter conditions of the Arctic.
Beyond the limits of the last tree, the planet is barren and ice-locked.
A frozen no-man's land at the end of the Earth.
But for a short time each year, the long, dark winter releases its grip.
Temperatures rise, and grass that has lain dormant and frozen throughout the winter sprouts once more.
Green returns to the Arctic.
The receding ice reveals an immense flat plain the size of Australia.
This is the Arctic tundra.
It's a desolate, silent wilderness. But it's about to change.