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Paleoclimatology (thesaurus)

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Terme préférentiel

Dryas  

Définition

  • The Dryas is the name given by palaeoclimatologists to a series of three cold periods of unequal duration, which occurred in the last phase of the Pleistocene, and which are dated to approximately 16,500 to 11,700 years before present (BP). The Dryas thus corresponds to a final cooling of the climate before the rapid warming that ended the last ice age and ushered in the temperate period of the Holocene. Paleoclimatologists distinguish, within the Tardiglacial (last phase of the last glacial period) : the Older Dryas, from around 16,500 to 14,600 years ago ; the Middle (or Oldest) Dryas, a short period of temperature relapse around 14,000 years ago ; the Younger Dryas, a period of more than 1,000 years, from around 12,900 to 11,700 years ago, characterized by abrupt cooling (7°C drop in mean temperature for the Northern Hemisphere). The Younger Dryas represents the very last glacial phase of the Pleistocene. It is followed by the Holocene, which begins with rapid warming. One hypothesis is that this cooling was produced by the rupture of a huge cold-water lake in North America, whose discharge into the North Atlantic blocked thermohaline circulation. This seems to contradict the fact that the Younger Dryas is a global episode, and not just one confined to Europe and North America. The three cold periods of the Dryas are interspersed by two episodes of temporary rise in temperatures, the Bölling interstadial, between Older and Middle Dryas, and the Alleröd interstadial, between Middle and Younger Dryas. (Adapted and translated from: https://fr.wikipedia.org/wiki/Dryas_(pal%C3%A9oclimat))

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http://data.loterre.fr/ark:/67375/QX8-8PCVHC5J-H

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