Tundra and taiga appear
Two entirely new biomes form at high northern latitudes as the world cools.
- When
- —
- Duration
- 420 thousand years
- Known to
- ± 300 thousand years
- Era
- Pliocene, Cenozoic
Boreal conifer forest and, beyond it, treeless tundra are geologically young: they form only once northern latitudes become cold enough to exclude broadleaf trees and, further north, all trees. Together they now cover a substantial fraction of the land surface and hold an enormous carbon store in permafrost and peat. Their appearance in the late Pliocene completes the set of modern biomes — from this point on, the map of world vegetation types is one a modern ecologist would recognise.