Variations in the Earth's orbit around the Sun, changes in the Earth's tilt, and variations in the Earth's wobble can all cause climate change over long periods of time.

Paleoclimatology is the study of past climates, including the causes and effects of climate change.

Ice core analysis is the most common method used to study past climates because ice cores contain a record of past atmospheric conditions.

The Pleistocene is the period of time between 2.6 million and 11,700 years ago.

The Holocene is the current geological epoch, which began 11,700 years ago.

The Pliocene is the period of time between 5.3 million and 2.6 million years ago.

The Miocene is the period of time between 23 million and 5.3 million years ago.

The Oligocene is the period of time between 36 million and 23 million years ago.

The Eocene is the period of time between 56 million and 36 million years ago.

The Paleocene is the period of time between 66 million and 56 million years ago.

The Cretaceous is the period of time between 145 million and 66 million years ago.

The Jurassic is the period of time between 201 million and 145 million years ago.

The Triassic is the period of time between 252 million and 201 million years ago.

The Permian is the period of time between 299 million and 252 million years ago.

The Carboniferous is the period of time between 359 million and 299 million years ago.