4.2 kilo-year event

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A 4.2-kilo-year event , 4.2-ka-event or 4.2-ka-BP-event for short , is a climate event or the connection between several climate events that occurred around 4200 years ago (4.2 ka for short) a BP , i.e. 4.2 thousand years before 1950). In various regions, especially the northern hemisphere, indications of periods of cooling and unusual drought were found during this period. According to numerous hypotheses about the effects of the 4,2-ka-BP event on the cultures existing at the time, it was probably one of the most momentous climatic cuts of the Holocene .

It continued around 2250 BC. And lasted the entire 22nd century BC. The collapse of the Old Kingdom in Egypt and the Akkadian Empire in Mesopotamia were probably triggered by him. The Indus civilization reacted to the prolonged drought by relocating their settlements to the southeast.

In chronostratigraphy , the 4,2-ka-BP event begins the Meghalayan , the highest stage of the Holocene . A speleothem from the Mawmluh cave in north-east India shows in a section in the δ 18 O isotope curve a rash dated to approx. 4200 BP, which clearly indicates exceptional dryness. This point is the GSSP of the Meghalayan.

proof

Reconstructed temperature records in central Greenland, obtained from the Gisp 2 ice core . Compared to the Misox fluctuation (8.2 kilo-year event), the 4.2-kilo-year event is only very indistinct.

A period of extreme drought that occurred 4,200 years ago can be clearly demonstrated for North Africa , the Middle East , the Red Sea , the Arabian Peninsula , the Indian subcontinent and for the interior of North America . At the same time, the glaciers in western Canada pushed forward again. Further evidence can be found in Italian cave deposits, in the ice cap of Kilimanjaro and in the glacier ice of the Andes . This period of drought, which began in Mesopotamia around 2150 BC. B.C. came to fruition and can be correlated with a cooling in the North Atlantic area , was also associated with the Bond event 3 .

The extent to which it was a uniform global event or whether different, regionally and temporally spaced climate events are referred to as 4.2-ka-BP events is still the subject of scientific research and discussion at the end of the 2010s.

Effects

Old Kingdom in Egypt

Around 2150 BC The Old Kingdom experienced a series of exceptionally low Nile floods that led to the collapse of central government. Famine, social turmoil and symptoms of social disintegration were the result. Large projects such as the pyramid construction came to a standstill. Only after 40 years could in some districts the old order be restored. After a change in the self-image of the Pharaohs, reunification finally succeeded, which was supported by capable provincial officials, judiciary, irrigation projects and a reform in the administration.

Mesopotamia

The drought in Mesopotamia may be causally related to cooler surface temperatures in the North Atlantic (Bond event 3). Modern measurements show that significant (more than 50%) reductions in annual precipitation in Mesopotamia always occur when the surface temperatures in the subpolar Northwest Atlantic experience anomalous cooling. The precipitation in the Euphrates and Tigris catchment areas, which comes from the eastern Mediterranean, occurs in winter and is caused by the altitude of eastern Anatolia.

The empire of Akkade , which was founded under Sargon von Akkad around 2300 BC. Was created - to Egypt, whose unification already around 3080 BC. The second comprehensive territorial state in history - experienced its inexorable decline due to the extremely long drought. Archaeologically it can be proven that around 2170 BC The agricultural plains of northern Mesopotamia were abandoned and as a result a flow of refugees to the south began. In order to prevent this influx of nomads, a 180-kilometer wall, the Amurriter dam , was built in central Mesopotamia . Demoralized by constant attacks, the Akkadian army was defeated in 2150 BC. Finally defeated by the Guteans coming from the Zagros , who then in 2115 BC The capital Akkad captured and destroyed.

Towards the end of the 3rd millennium BC A significant change in agriculture can be observed throughout the Middle East. Only around 1900 BC 200 years after the collapse of the Akkadian Empire, the northern plains were repopulated by smaller, sedentary groups.

Arabian Peninsula

In the Persian Gulf , the 4.2 kilo-year event can be recognized by a drastic change in settlement construction, in the ceramic style and in the grave complexes. The drought of the 22nd century BC BC marked the end of the Umm-an-Nar culture and the transition to the Wadi-Suq culture .

China

In central China , the drought may have been responsible for the collapse of the Neolithic cultures towards the end of the 3rd millennium. At that time, a series of exceptional floods occurred on the middle reaches of the Yellow River . In the Yishu Basin in Shandong , the flourishing Longshan culture was plagued by sudden drops in temperature, which resulted in a drastic reduction in rice production. The food shortage in turn caused a significant population decline, which is reflected in a far lower number of archaeological sites. Around 2000 BC The Longshan culture was replaced by the Yueshi culture , which compared to its predecessor has underdeveloped and much simpler features.

Mauritius

Research has shown that around 2200 BC For about 50 years there was a great drought on the island of Mauritius ; probably because the usual monsoon rains were missing.

Individual evidence

  1. ↑ a b deMenocal, Peter B .: Cultural Responses to Climate Change During the Late Holocene . In: Science . tape 292 , no. 5517 , 2001, p. 667-673 , doi : 10.1126 / science.1059287 .
  2. ↑ Gibbons, Ann: How the Akkadian Empire Was Hung Out to Dry . In: Science . tape 261 , no. 5124 , 1993, pp. 985 , doi : 10.1126 / science.261.5124.985 .
  3. ↑ a b Staubwasser, M. et al .: Climate change at the 4.2 ka BP termination of the Indus valley civilization and Holocene south Asian monsoon variability . In: Geophysical Research Letters . tape 30 , no. 8 , 2003, p. 1425 , doi : 10.1029 / 2002GL016822 .
  4. ↑ Mike Walker, Phil Gibbard, Martin J. Head, Max Berkelhammer, Svante Björck, Hai Cheng, Les C. Cwynar, David Fisher, Vasilios Gkinis, Antony Long, John Lowe, Rewi Newnham, Sune Olander Rasmussen, Harvey Weiss: Formal Subdivision of the Holocene Series / Epoch: A Summary . In: Journal Geological Society India . tape 93 , February 2019, doi : 10.1007 / s12594-019-1141-9 .
  5. ^ Gasse, Françoise and Van Campo, Elise: Abrupt post-glacial climate events in West Asia and North Africa monsoon domains . In: Earth and Planetary Science Letters . tape 126 , no. 4 , 1994, pp. 435-456 , doi : 10.1016 / 0012-821X (94) 90123-6 .
  6. ↑ Bar-Matthews, Miryam; Ayalon, Avner and Kaufman, Aaron: Late Quaternary Paleoclimate in the Eastern Mediterranean Region from Stable Isotope Analysis of Speleothems at Soreq Cave, Israel . In: Quaternary Research . tape 47 , no. 2 , 1997, p. 155-168 , doi : 10.1006 / qres.1997.1883 .
  7. ↑ Arz, Helge W. et al .: A pronounced dry event recorded around 4.2 ka in brine sediments from the northern Red Sea . In: Quaternary Research . tape 66 , no. 3 , 2006, p. 432-441 , doi : 10.1016 / j.yqres.2006.05.006 .
  8. ↑ a b Parker, Adrian G. et al .: A record of Holocene climate change from lake geochemical analyzes in southeastern Arabia . In: Quaternary Research . tape 66 , no. 3 , 2006, p. 465-476 , doi : 10.1016 / j.yqres.2006.07.001 .
  9. ↑ Booth, Robert K. et al .: A severe centennial-scale drought in midcontinental North America 4200 years ago and apparent global linkages . In: The Holocene . tape 15 , no. 3 , 2005, p. 321-328 , doi : 10.1191 / 0959683605hl825ft .
  10. ↑ Menounos, B. et al: Western Canadian glaciers advance in concert with climate change circa 4.2 ka . In: Geophysical Research Letters . tape 35 , no. 7 , 2008, p. L07501 , doi : 10.1029 / 2008GL033172 .
  11. ^ Drysdale, Russell et al .: Late Holocene drought responsible for the collapse of Old World civilizations is recorded in an Italian cave flowstone . In: Geology . tape 34 , no. 2 , 2005, p. 101-104 , doi : 10.1130 / G22103.1 .
  12. ↑ Thompson, LG et al .: Kilimanjaro Ice Core Records Evidence of Holocene Climate Change in Tropical Africa . In: Science . tape 298 , 2002, pp. 589 , doi : 10.1126 / science.1073198 .
  13. ^ Davis, Mary E. and Thompson, Lonnie G .: An Andean ice-core record of a Middle Holocene mega-drought in North Africa and Asia . In: Annals of Glaciology . tape 43 , 2006, p. 34-41 , doi : 10.3189 / 172756406781812456 .
  14. ^ Paul Voosen: New geological age comes under fire - timing and extent of ancient drought used to define the Meghalayan are uncertain . In: Science . tape 361 , no. 6402 , August 2018, doi : 10.1126 / science.361.6402.537 .
  15. ^ Stanley, Jean-Daniel et al.: Nile flow failure at the end of the Old Kingdom, Egypt: Strontium isotopic and petrologic evidence . In: Geoarchaeology . tape 18 , no. 3 , 2003, p. 395-402 , doi : 10.1002 / gea.10065 .
  16. ↑ Heidi Cullen , deMenocal, Peter B .: North Atlantic influence on Tigris-Euphrates streamflow . In: International Journal of Climatology . tape 20 , no. 8 , 2000, pp. 853-863 , doi : 10.1002 / 1097-0088 (20000630) 20: 8 <853 :: AID-JOC497> 3.0.CO; 2-M .
  17. ↑ Kerr, Richard A .: Sea-Floor Dust Shows Drought Felled Akkadian Empire . In: Science . tape 279 , no. 5349 , 1998, pp. 325–326 , doi : 10.1126 / science.279.5349.325 .
  18. ↑ a b Weiss, H. et al .: The Genesis and Collapse of Third Millennium North Mesopotamian Civilization . In: Science . tape 261 , no. 5124 , 1993, pp. 995-1004 , doi : 10.1126 / science.261.5124.995 .
  19. ↑ Riehl, S .: Climate and agriculture in the ancient Near East: a synthesis of the archaeobotanical and stable carbon isotope evidence . In: Vegetation History and Archaeobotany . tape 17 , no. 1 , 2008, p. 43-51 , doi : 10.1007 / s00334-008-0156-8 .
  20. ↑ Wu, Wenxiang and Liu, Tung Sheng: Possible role of the 'Holocene Event 3 "on the collapse of Neolithic Cultures around the Central Plain of China . In: Quaternary International . tape 117 , no. 1 , 2004, p. 153-166 , doi : 10.1016 / S1040-6182 (03) 00125-3 .
  21. ↑ Chun Chang Huang et al .: Extraordinary floods related to the climatic event at 4200 a BP on the Qishuihe River, middle reaches of the Yellow River, China . In: Quaternary Science Reviews . tape 30 (3–4) , 2011, pp. 460-468 , doi : 10.1016 / j.quascirev.2010.12.007 .
  22. ^ Gao, Huazhong, Zhu, Chengund Xu, Weifeng: Environmental change and cultural response around 4200 cal. Yr BP in the Yishu River Basin, Shandong . In: Journal of Geographical Sciences . tape 17 , no. 3 , 2007, p. 285-292 , doi : 10.1007 / s11442-007-0285-5 .
  23. ↑ Megadrought poisoned dodos with their own feces . @ Spektrum.de, April 29, 2015 with reference to A deadly cocktail: How a drought around 4200 cal. yr BP caused mass mortality events at the infamous 'dodo swamp' in Mauritius. ( Memento from July 6, 2015 in the Internet Archive ) “Analyzes of pollen, diatoms, XRF geochemistry, and pigments provide a unique window into how an insular ecosystem in Mauritius responded to an extreme drought event 4200 years ago ... This prolonged drought around the Indian Ocean is recorded in many regions dependent on monsoon precipitation and is suggested to cause the collapse of human societies in East Africa and India ... Abrupt increased aridity induced regional fires on Mauritius and caused decreased water levels, and a shrinking water surface resulting in further concentration of the animals in this coastal site ... The '4.2 ka megadrought' likely induced similar bottlenecks elsewhere in the SW Indian Ocean region. ", accessed May 30, 2015