Oldest terrestrial biome

Earth’s current rainforests have been established for at least a million years. The last Ice Age, which ended around 10,000 years ago, had covered much of the world’s forests in ice, but left the equatorial forests uncovered.

The pollen record reveals that although tropical rainforests survived the last Ice Age, temperatures were then 5–6°C (9–10.8°F) cooler on average, so the forests underwent changes. For example, plants that were better suited to colder climates were able to establish themselves in the rainforest biome at this time.

Antarctica has a claim to be the oldest unchanged biome. It has shrunk since the last Ice Age, but the core that exists today – home to photosynthetic bacteria, mosses and microscopic worms – has remained in its original state.

In August 2017, scientists revealed that they had removed an ice core some 2.7 million years old from Allan Hills in East Antarctica. Air bubbles within the ice contain samples of Earth's atmosphere from that period, just before the wave of ice ages began.