Palaeoclimatology

Palaeoclimatology (or paleoclimatology) is the study of changes in climate over the entire history of Earth. Modern interest in climate change has caused a great increase in the climates of the past.
The climates of the past can only be studied by proxy. Data is got from rocks, sediments, ice and tree rings, corals, shells and microfossils. These records are used to work out the past states of the Earth's climate and its atmospheric system.
Studies of past changes in the life and ecosystems of the past may throw a light on the present. An example is the effect of climate on mass extinctions and the recovery of life after those extinctions.
Notable climate events in Earth history.
Knowledge of precise climatic events decreases as the record goes further back in time. Some notable climate events: