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 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]
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
Palaeotemperature graphs placed together
The oxygen content in the atmosphere over the last billion years
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.
Timeline of glaciations, shown in blue
Changes in oxygen-18 ratios over the last 500 million years, indicating environmental change
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 Template:CO2 concentrations, and brown curve is dust fluxes. Note length of glacial-interglacial cycles averages ~100,000 years.
Holocene Temperature Variations
References
- ↑ Sahney S. and Benton M.J. (2008). "Recovery from the most profound mass extinction of all time". Proceedings of the Royal Society: Biological. 275 (1636): 759–65. doi:10.1098/rspb.2007.1370. PMC 2596898. PMID 18198148.