Palaeoclimatology

Palaeoclimatology (or paleoclimatology) is the study of changes in climate over paleontology or 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 comes from studying 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.^[1]

Knowledge of precise climatic events decreases as the record goes further back in time. Some notable climate events:

• Faint young Sun
• Huronian glaciation (~2400 mya Earth completely covered in ice probably due to Great Oxygenation Event)
• Later Neoproterozoic Snowball Earth (~600 mya, precursor to the Cambrian Explosion)
• Carboniferous rainforest collapse (~300 mya)
• Permian–Triassic extinction event (251.4 mya)
• Oceanic Anoxic Events (~120 mya, 93 mya, and others)
• Cretaceous–Paleogene extinction event (66 mya)
• Paleocene–Eocene thermal maximum (Paleocene–Eocene, 55mya)
• Younger Dryas/The Big Freeze (~11 kya)
• Holocene climatic optimum (~7-3 kya)
• Climate changes of 535–536 AD
• Medieval warm period (900–1300)
• Little ice age (1300–1800)