- 5.9 kiloyear event
The 5.9 kiloyear event was one of the most intense aridification events during the
Holocene . It ended theNeolithic Subpluvial and probably initiated the desiccation of theSahara desert. Thus, it also triggered world-wide migration to river valleys, e.g. from centralNorth Africa to theNile valley , what eventually led to the emergence of first complex, highly organised, state-level societies in the4th millennium BC . cite journal | last = Brooks | first = Nick | authorlink = | coauthors = | year = 2006 | month = | title = Cultural responses to aridity in the Middle Holocene and increased social complexity | journal = Quaternary International | volume = 151 | issue = 1 | pages = 29–49 | doi = 10.1016/j.quaint.2006.01.013 | url = | accessdate = | quote = ]A model by Claussen "et al." (1999) suggested rapid desertification associated with vegetation atmosphere interactions following the 5.9 kiloyear cooling event (Bond event 4). cite journal | last = Claussen | first = Mark | authorlink = | coauthors = "et al." | year = 1999 | month = | title = Simulation of an Abrupt Change in Saharan Vegetation in the Mid-Holocene | journal = Geophysical Research Letters | volume = 26| issue = 14 | pages = 2037–2040 | doi = | url = http://www.agu.org/pubs/crossref/1999/1999GL900494.shtml | accessdate = | quote = ]
Bond "et at." (1997) identified a North Atlantic cooling episode at 5,900 BP from ice-rafted debris, as well as other such now called
Bond event s that indicate the existence of a quasiperiodic cycle of Atlantic cooling events, which occur approximately every 1500 years.cite journal| author = Bond, G. | coauthors = "et al." | url=http://rivernet.ncsu.edu/courselocker/PaleoClimate/Bond%20et%20al.,%201997%20Millenial%20Scale%20Holocene%20Change.pdf | year = 1997 | title = A Pervasive Millennial-Scale Cycle in North Atlantic Holocene and Glacial Climates | journal = Science | volume = 278 | issue = 5341 | pages = 1257-1266 | doi = 10.1126/science.278.5341.1257 ] For some reason, all of the earlier of these arid events (including the8.2 kiloyear event ) were followed by recovery, as attested by the wealth of evidence of humid conditions in the Sahara between 10,000 and 6,000 BP.cite book |title=Third Millennium BC Climate Change and Old World Collapse |chapter=Holocene climate change and man in the present day Sahara desert |last=Petit-Maire |first=N. |authorlink= |coauthors= Beufort, L.; Page, N. |editor=Nüzhet Dalfes, H.; Kukla, G.; Weiss, H. (Eds.) |year=1997 |publisher=Springer |location=Berlin |isbn=3540618929 |pages=297–308 ] However, it appears that the 5.9 kiloyear event was followed by a partial recovery at best, with accelerated desiccation in the millennium that followed. For example, Cremaschi (1998) describes evidence of rapid aridification inTadrart Acacus of southwesternLibya , in the form of increased aeolian erosion, sand incursions and the collapse of the roofs of rock shelters.cite book |title=Wadi Teshuinat: Palaeoenvironment and prehistory in south-western Fezzan(Libyan Sahara) |chapter=Late Quaternary geological evidence for environmental changes in south-western Fezzan (Libyan Sahara) |last=Cremaschi |first=M. |authorlink= |editor=Cremaschi, M.; Di Lernia, S. (Eds.) |year=1998 |publisher=Ed. All' Insegna del Giglio |location=Firenze |isbn=8878141445 |pages=13–47 ]In the
Middle East the 5.9 kiloyear event led to the abrupt end of theUbaid period . cite journal | last = Parker | first = Adrian G. | authorlink = | coauthors = "et al." | year = 2006 | month = | title = A record of Holocene climate change from lake geochemical analyses in southeastern Arabia | journal = Quaternary Research | volume = 66 | issue = 3 | pages = 465–476 | doi = 10.1016/j.yqres.2006.07.001 | url = http://www.gulfnexus.org/articles/geo/2006a%20Parker%20et%20al.pdf | accessdate = | quote = ]The 5.9 kiloyear event was also recorded as a cold event in the
Erhai Lake (China) sediments. cite journal | author = Zhou Jing | authorlink = | coauthors = Wang Sumin; Yang Guishan; Xiao Haifeng | year = 2007 | month = | title = Younger Dryas Event and Cold Events in Early-Mid Holocene: Record from the sediment of Erhai Lake | journal = Advances in Climate Change Research | volume = 3 | issue = Suppl. | pages = 1673–1719 | id = | url = http://www.climatechange.cn/qikan/manage/wenzhang/08.pdf | accessdate = | quote = ]References
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