Geographical sites:

  • Mesopotamia (click here to focus in map) (see also Pleiades #981534)
    Pleiades_icon Mesopotamia province Geocontext: province
    Description: An ancient place, cited: BAtlas 100 P4 Mesopotamia
  • Egypt (click here to focus in map) (see also Pleiades #766)
    Pleiades_icon Aegyptus province, region Geocontext: Egypt
    Description: The Roman province of Egypt (Aegyptus) was established in 30 BC after the defeat of Marcus Antonius and Cleopatra VII at the Battle of Actium.
  • North Atlantic Ocean (click here to focus in map) (see also GeoNames #3411923)
    Geonames_icon North Atlantic Ocean ocean Geocontext: America/Danmarkshavn
  • India (click here to focus in map) (see also Pleiades #50004)
    Pleiades_icon India region Geocontext: Barrington Atlas grid 5 D2
    Description: An ancient place, cited: BAtlas 5 D2 India
  • North America (click here to focus in map) (see also GeoNames #6255149)
    Geonames_icon North America continent Geocontext: America/Cambridge_Bay
  • Italy (click here to focus in map) (see also GeoNames #3175395)
    Geonames_icon Repubblica Italiana independent political entity Geocontext: Europe/Rome
  • Andes (click here to focus in map) (see also GeoNames #3923974)
    Geonames_icon Andes Mountains mountains Geocontext: America/Lima
    Description: BO,EC,CL,CO,AR,VE,PE
  • Greenland (click here to focus in map) (see also GeoNames #3425505)
    Geonames_icon Greenland dependent political entity Description: GL
  • Norway (click here to focus in map) (see also GeoNames #3144096)
    Geonames_icon Kingdom of Norway independent political entity Geocontext: Europe/Oslo
  • China (click here to focus in map) (see also GeoNames #1814991)
    Geonames_icon People’s Republic of China independent political entity


Text #9339

"The 4.2 Kiloyear Event", in Wikipedia.

The 4.2 kiloyear BP aridification event was one of the most severe climatic events of the Holocene period in terms of impact on cultural upheaval. Starting in about 2200 BC, it probably lasted the entire 22nd century BC. It is very likely to have caused the collapse of the Old Kingdom in Egypt as well as the Akkadian Empire in Mesopotamia. The drought may have also initiated southeastward habitat tracking within the Indus Valley Civilization.

A phase of intense aridity about 4.2 ka BP is recorded across North Africa, the Middle East, the Red Sea, the Arabian peninsula, the Indian subcontinent, and midcontinental North America. Glaciers throughout the mountain ranges of western Canada advanced at about this time. Evidence has also been found in an Italian cave flowstone, the Kilimanjaro Ice sheet, and in Andean glacier ice. The onset of the aridification in Mesopotamia about 4100 BP also coincided with a cooling event in the North Atlantic, known as Bond event 3. Despite this, evidence for the 4.2 kyr event in northern Europe is ambiguous, suggesting the origin and impact of this event is spatially complex.

Ancient Egypt

In c. 2150 BC the Old Kingdom was hit by a series of exceptionally low Nile floods, which was instrumental in the sudden collapse of centralized government in ancient Egypt. Famines, social disorder, and fragmentation during a period of approximately 40 years were followed by a phase of rehabilitation and restoration of order in various provinces. Egypt was eventually reunified within a new paradigm of kingship. The process of recovery depended on capable provincial administrators, the deployment of the idea of justice, irrigation projects, and an administrative reform.


The aridification of Mesopotamia may have been related to the onset of cooler sea surface temperatures in the North Atlantic (Bond event 3), as analysis of the modern instrumental record shows that large (50%) interannual reductions in Mesopotamian water supply result when subpolar northwest Atlantic sea surface temperatures are anomalously cool. The headwaters of the Tigris and Euphrates Rivers are fed by elevation-induced capture of winter Mediterranean rainfall.

The Akkadian Empire—which in 2300 BC was the second civilization to subsume independent societies into a single state (the first being ancient Egypt at around 3100 BC) —was brought low by a wide-ranging, centuries-long drought. Archaeological evidence documents widespread abandonment of the agricultural plains of northern Mesopotamia and dramatic influxes of refugees into southern Mesopotamia around 2170 BC. A 180-km-long wall, the “Repeller of the Amorites,” was built across central Mesopotamia to stem nomadic incursions to the south. Around 2150 BC, the Gutian people, who originally inhabited the Zagros Mountains, defeated the demoralized Akkadian army, took Akkad, and destroyed it around 2115 BC. Widespread agricultural change in the Near East is visible at the end of the third millennium BC.

Resettlement of the northern plains by smaller sedentary populations occurred near 1900 BC, three centuries after the collapse.

Text #9332

"Bond Event", in Wikipedia.

Bond events are North Atlantic climate fluctuations occurring every ≈1,470 ± 500 years throughout the Holocene. Eight such events have been identified, primarily from fluctuations in ice-rafted debris. Bond events may be the interglacial relatives of the glacial Dansgaard–Oeschger events, with a magnitude of perhaps 15–20% of the glacial-interglacial temperature change.

Gerard C. Bond of the Lamont–Doherty Earth Observatory at Columbia University, was the lead author of the 1997 paper that postulated the theory of 1,470-year climate cycles in the Holocene, mainly based on petrologic tracers of drift ice in the North Atlantic.

The existence of climatic changes, possibly on a quasi-1,500 year cycle, is well established for the last glacial period from ice cores. Less well established is the continuation of these cycles into the holocene. Bond et al. (1997) argue for a cyclicity close to 1470 ± 500 years in the North Atlantic region, and that their results imply a variation in Holocene climate in this region. In their view, many if not most of the Dansgaard–Oeschger events of the last ice age, conform to a 1,500-year pattern, as do some climate events of later eras, like the Little Ice Age, the 8.2 kiloyear event, and the start of the Younger Dryas.

The North Atlantic ice-rafting events happen to correlate with most weak events of the Asian monsoon for at least the past 9,000 years,[4][5] while also correlating with most aridification events in the Middle East for the past 55,000 years (both Heinrich and Bond events). Also, there is widespread evidence that a ≈1,500 yr climate oscillation caused changes in vegetation communities across all of North America.

For reasons that are unclear, the only Holocene Bond event that has a clear temperature signal in the Greenland ice cores is the 8.2 kyr event.

The hypothesis holds that the 1,500-year cycle displays nonlinear behavior and stochastic resonance; not every instance of the pattern is a significant climate event, though some rise to major prominence in environmental history. Causes and determining factors of the cycle are under study; researchers have focused attention on variations in solar output, and “reorganizations of atmospheric circulation.” Bond events may also be correlated with the 1800-year lunar tidal cycle.

0 ≈0.5 ka Little Ice Age
1 ≈1.4 ka Migration Period
2 ≈2.8 ka early 1st millennium BC drought in the Eastern Mediterranean, possibly triggering the collapse of Late Bronze Age cultures.
3 ≈4.2 ka 4.2 kiloyear event; collapse of the Akkadian Empire and the end of the Egyptian Old Kingdom.
4 ≈5.9 ka See 5.9 kiloyear event;
5 ≈8.2 ka See 8.2 kiloyear event;
6 ≈9.4 ka Erdalen event of glacier activity in Norway, as well as with a cold event in China.
7 ≈10.3 ka 8 ≈11.1 ka transition from the Younger Dryas to the boreal.

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