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Concept information

... > geologic time scale > geological age > Phanerozoic > Cenozoic > Quaternary > Holocene > Holocene climatic optimum
scientific discipline > stratigraphy > climatostratigraphy > climatostratigraphic period > Holocene climatic optimum

Preferred term

Holocene climatic optimum  

Definition

  • The Holocene Climate Optimum (HCO) was a warm period in the first half of the Holocene epoch, that occurred in the interval roughly 9,500 to 5,500 years BP,[1] with a thermal maximum around 8000 years BP. It has also been known by many other names, such as Altithermal, Climatic Optimum, Holocene Megathermal, Holocene Optimum, Holocene Thermal Maximum, Hypsithermal, and Mid-Holocene Warm Period. The warm period was followed by a gradual decline, of about 0.1 to 0.3 °C per millennium, until about two centuries ago. However, on a sub-millennial scale, there were regional warm periods superimposed on this decline. The HCO was approximately 4.9 °C warmer than the Last Glacial Maximum. A study in 2020 estimated that the average global temperature during the warmest 200 year period of the HCO, around 6,500 years ago, was around 0.7 °C warmer than the mean for nineteenth century AD, immediately before the Industrial Revolution, and 0.3 °C cooler than the average for 2011-2019. The 2021 IPCC report expressed medium confidence that temperatures in the last decade are higher than they were in the Mid-Holocene Warm Period. Temperatures in the Northern Hemisphere are simulated to be warmer than present average during the summers, but the tropics and parts of the Southern Hemisphere were colder than average. The average temperature change appears to have declined rapidly with latitude and so essentially no change in mean temperature is reported at low and middle latitudes. Tropical reefs tend to show temperature increases of less than 1 °C. The tropical ocean surface at the Great Barrier Reef about 5350 years ago was 1 °C warmer and enriched in 18O by 0.5 per mil relative to modern seawater. Temperatures during the HCO were higher than in the present by around 6 °C in Svalbard, near the North Pole. The climatic event was probably a result of predictable changes in the Earth's orbit (Milankovitch cycles) and a continuation of changes that caused the end of the last glacial period. (Adapted from: https://en.wikipedia.org/wiki/Holocene_climatic_optimum)

Broader concept

Entry terms

  • Altithermal
  • Holocene Megathermal
  • Holocene Optimum
  • Holocene Thermal Maximum
  • Hypsithermal
  • Mid-Holocene Warm Period

In other languages

  • optimum climatique de l'Holocène

    French

  • Altithermal
  • Hypsithermal
  • optimum climatique holocène
  • optimum climatique post-glacaire
  • période altithermale
  • période hypsithermale

URI

http://data.loterre.fr/ark:/67375/QX8-3X5KZ9GQ-C

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