Across much of the world, the 8.2 kiloyear event engendered drier environmental conditions. Northern Hemisphere monsoon precipitation declined by 12.4% for every °C of global mean temperature change, while Southern Hemisphere monsoon precipitation rose by 4.2%/°C. The 8.2 kiloyear event was also associated with an increase in ocean salinity and terrestrial dust flux.
North Africa and Mesopotamia 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.
East Africa was significantly affected by five centuries of general
drought. 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. 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. In particular, in
Tell Sabi Abyad,
Syria, significant cultural changes were observed at c. 6200 BC; the settlement was not abandoned at the time.
Madagascar 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. Summer monsoons in the Southern Hemisphere likely became stronger, contributing to precipitation increases. Humidification was two-phased, with an 8.3 kiloyear sub-event preceding the 8.2 kiloyear sub-event by about 20 years.
Europe 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. In western
Scotland, the 8.2 kiloyear event coincided with a dramatic reduction in the Mesolithic population. Around
Lake Mondsee in the
Alps of
Austria, deciduous forests declined while boreal vegetation took over. 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. At Tenaghi Philippon in northeastern
Greece, average winter temperatures dropped by over 4 °C, likely due to increased influence of the
Siberian High.
North Asia Lacustrine sediment records show that Western Siberia underwent humidification during the 8.2 kiloyear event. Southeastern Siberia experienced a precipitation decline.
South Asia Carbonates from the Riwasa Palaeolake show a weakening of the Indian Summer Monsoon (ISM) synchronous with the 8.2 kiloyear event. Stalagmites from Kotumsar Cave and from
Socotra and
Oman further confirm the ISM precipitously diminished in strength.
East Asia A sediment core from
Lop Nur in the
Tarim Basin shows a major dry spell occurred during the 8.2 kiloyear event. The impact of the 8.2 kiloyear event on
forests in the
Korean Peninsula was severe, shown by a sizeable reduction in
pollen production. It took approximately 400 years for forest
ecosystems to recover from the event to their state before the climatic perturbation.
Southeast Asia Evidence from the
Gulf of Thailand reveals that a sea level drop occurred concordantly with the 8.2 kiloyear event. Also detectable from
palynological and
sedimentological records is an increase in runoff. Rainfall in the
Indo-Pacific Warm Pool (IPWP) decreased for about 200 years, though this hydroclimatic response lagged the North Atlantic cooling by about 100 years.
North America In Greenland, the 8.2 kiloyear event is associated with a large negative spike in ice core δ18O values. Elk Lake in
Minnesota shifted from being well stratified to well mixed, and the area around it went from boreal forest to open prairie savanna. The waters off
Cape Hatteras experienced a major increase in
salinity.
Bat guano δ13C and
δD values in the
Grand Canyon declined. Southwestern Mexico became significantly drier, evidenced by the interruption of stalagmite growth. In the
Gulf of Mexico, bay-head deltas back stepped as sea levels rose.
Mustang Island was breached and ceased to be an effective salinity barrier. Gulf of Mexico δ18Oseawater values dropped by 0.8%.
South America In the Western Cordillera of
Colombia, the 8.2 kiloyear event coincides with a major dry event. The South American Summer Monsoon (SASM) drastically intensified during the 8.2 kiloyear event as revealed by sediment records from Juréia Paleolagoon. == See also ==