Antarctica freezes
The last strait opens and isolates the continent
See it on the timeline →In depth
The opening of the Drake Passage and the Tasmanian Gateway established the Antarctic Circumpolar Current, which thermally isolates the continent from the rest of the world ocean. Combined with falling CO₂, this tipped the climate over a threshold at the Eocene–Oligocene transition: the ice sheet built rapidly, sea level fell, and the planet moved from a greenhouse into what is called an icehouse state — which it is still in. Antarctica today holds around 60 per cent of the world's fresh water. Fossil Nothofagus forests still lie in its mountains, beneath the ice.
For children
Antarctica had forests and animals for as long as it stayed joined to South America and Australia. When the last land bridges broke, an ocean current could run all the way around the continent — like a wall of cold water. Inside that wall everything froze. The ice has been there ever since.
Connects to
Part of Terra Saga — the story of Earth on a timeline. terrasaga.org