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.

File:All palaeotemps.png

Palaeotemperature graphs compressed together

Notable climate events in Earth history

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)

Palaeoclimatology Media

• Earth's average surface temperature over the past 500 million years.png

  Preliminary results from a Smithsonian Institution project, showing Earth's average surface temperature over the past 500 million years

• Palaeotemperature graphs placed together

• Sauerstoffgehalt-1000mj2.png

  The oxygen content in the atmosphere over the last billion years

• Core+Repository+core samples2.jpg

  Sea floor core sample labelled to identify the exact spot on the sea floor where the sample was taken. Sediments from nearby locations can show significant differences in chemical and biological composition.

• GlaciationsinEarthExistancelicenced annotated.jpg

  Timeline of glaciations, shown in blue

• Phanerozoic Climate Change.png

  Changes in oxygen-18 ratios over the last 500 million years, indicating environmental change

• "EDC TempCO2Dust".svg

  Ice core data for the past 800,000 years (x-axis values represent "age before 1950", so today's date is on the left side of the graph and older time on the right). Blue curve is temperature, red curve is atmospheric CO₂ concentrations, and brown curve is dust fluxes. Note length of glacial-interglacial cycles averages ~100,000 years.

• Holocene Temperature Variations.png

  Holocene temperature variations