8.2-kiloyear event
During the 8.2-kiloyear event, atmospheric methane levels dropped by 80 parts per billion, a 15% reduction, suggesting a broad cooling and drying trend across the Northern Hemisphere.
A rapid cooling around 8,200 years ago was first identified by Swiss botanist Heinrich Zoller in 1960, who named the event the Misox oscillation for the Val Mesolcina[2].
[citation needed] Researchers suggest that the discharge was probably superimposed upon a longer episode of cooler climate lasting up to 600 years, and it was merely one contributing factor to the event as a whole.
[21] Further afield from the Laurentide Ice Sheet, some tropical records report a 3 °C (5.4 °F) cooling, based on cores drilled into an ancient coral reef in Indonesia.
In 2003, the Office of Net Assessment (ONA) at the United States Department of Defense was commissioned to produce a study on the likely and potential effects of modern climate change.
[28] The study, conducted under ONA head Andrew Marshall, modeled its prospective climate change on the 8.2 kiloyear event, precisely because it was the middle alternative between the Younger Dryas and the milder Little Ice Age.
[32] Drier conditions were notable in North Africa; the area around the Charef River in eastern Morocco records an episode of extreme aridity around 8,200 BP.
In West Asia, especially Mesopotamia, the 8.2-kiloyear event was a 300-year aridification and cooling episode which may have provided the natural force for Mesopotamian irrigation agriculture and surplus production, which were essential for the earliest formation of classes and urban life.
[citation needed] However, changes taking place over centuries around the period are difficult to link specifically to the approximately 100-year abrupt event, as recorded most clearly in the Greenland ice cores.
[34] In northwestern Madagascar, the 8.2 kiloyear event is associated with a negative δ18O excursion and calcite deposition, indicating wet, humid conditions caused by the southward migration of the ITCZ.
[37] The sediment core records of the Fram Strait show a short-lived cooling during the 8.2 kiloyear event superimposed on a broader interval of warm climate.
[39] In the Iberian Peninsula, the 8.2 kiloyear event is linked to greater summer aridity that caused an increase in the frequency of fires and a consequent expansion of fire-resistant evergreen oak trees.
