The Cenozoic Era

Throughout this period, Earth’s climate was cooling down. This cooling wasn’t a smooth decline but a sequence of warmer and cooler periods. The sea levels dropped dramatically between 50 million and 38 million years, indicating a new glaciation. Antarctica became climatically isolated due to the opening of the southern polar ocean when South America and Australia drifted northward. The Antarctic ice sheet grew, although evidence of Antarctic forest can be found even for a time of 25 million years ago.

At 12-14 million years, mountain glaciers are forming on the continents of the Northern hemisphere. The Arctic Ocean formed an ice cap at about 5 million years ago.

Shorter-lived disturbances in climate are attributed to processes involving the isolation and then opening of the Mediterranean Sea, which influenced sea levels and salinity of oceans world wide.

During the Pleistocene period up to 32% of the Earth’s surface were covered with ice. The glaciations were a fluctuating process with increasing amplitude, seven major periods known during the last 1.6 million years.

Notably, the first indications of human civilization align with the end of the last glaciation period.