Climate and ecology

The current geological age is called the Quaternary; it began 2.5 million years ago. During the Quaternary, there have been continuous cycles of increasing and decreasing temperature. Many of the cooler times were glacial periods, and the warmer times interglacials. These climatic changes have happened recently enough for the fossil record in some cases to be revealingly complete. When the weather turns cool, animals tend to migrate southwards and plant ranges contract. At any one site, the local ecology changes to one characteristic of the cooler climate; a change from a temperate to a tundra-type ecosystem has been well documented, from pollen records, in the northern temperate zone through recent Ice Ages.

The image opposite shows a range of different climates throughout the world today; each climate having a distinct flora and fauna. Clockwise from top left: neartic, neo-tropical, paleartic, ethiopian.