Bond event

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 1470-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, like some climate events of later eras such as 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 9000 years and also correlate 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 1500-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.

List

Most Bond events do not have a clear climate signal; some correspond to periods of cooling, but others are coincident with aridification in some regions.

No.	Time (BP)	Time (AD, BC)	Notes
0	≈ −0.5 ka	≈ 1500 AD	See Little Ice Age;
1	≈ −1.4 ka	≈ 600 AD	See Migration Period;
2	≈ −2.8 ka	≈ 800 BC	Late Bronze Age collapse may have been triggered by drought in the Eastern Mediterranean.
3	≈ −4.2 ka	≈ 2200 BC	See 4.2 kiloyear event; collapse of the Akkadian Empire and the end of the Egyptian Old Kingdom.
4	≈ −5.9 ka	≈ 3900 BC	See 5.9 kiloyear event;
5	≈ −8.2 ka	≈ 6200 BC	See 8.2 kiloyear event;
6	≈ −9.4 ka	≈ 7400 BC	Erdalen event of glacier activity in Norway, as well as with a cold event in China.
7	≈ −10.3 ka	≈ 8300 BC
8	≈ −11.1 ka	≈ 9100 BC	transition from the Younger Dryas to the boreal.

See also

• Ice sheet dynamics
• Heinrich event