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    Geonames_icon North Atlantic Ocean ocean Geocontext: America/Danmarkshavn
  • Greenland (click here to focus in map) (see also GeoNames #3425505)
    Geonames_icon Greenland dependent political entity Description: GL
  • Antarctica (click here to focus in map) (see also GeoNames #6697173)
    Geonames_icon Antarctica territory
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    Geonames_icon Kingdom of Norway independent political entity Geocontext: Europe/Oslo
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    Geonames_icon People’s Republic of China independent political entity


Text #9331

"The 8.2 Kiloyear Event", in Wikipedia.

The 8.2 kiloyear event is the term that climatologists have adopted for a sudden decrease in global temperatures that occurred approximately 8,200 years before the present, or c. 6,200 BCE, and which lasted for the next two to four centuries. Milder than the Younger Dryas cold spell that preceded it, but more severe than the Little Ice Age that would follow, the 8.2 kiloyear cooling was a significant exception to general trends of the Holocene climatic optimum. During the event, atmospheric methane concentration decreased by 80 ppb or an emission reduction of 15%, by cooling and drying at a hemispheric scale.

A rapid cooling around 6200 BCE was first identified by Swiss botanist Heinrich Zoller in 1960, who named the event Misox oscillation (for the Val Mesolcina). It is also known as Finse event in Norway. Bond et al. argued that the origin of the 8.2 kiloyear event is linked to a 1,500-year climate cycle; it correlates with Bond event 5.

The strongest evidence for the event comes from the North Atlantic region; the disruption in climate shows clearly in Greenland ice cores and in sedimentary and other records of the temporal and tropical North Atlantic. It is less evident in ice cores from Antarctica and in South American indices. The effects of the cold snap were global, however, most notably in changes in sea level during the relevant era.

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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