abstract
| - The theory of 1,500-year climate cycles in the Holocene was postulated by Gerard C. Bond of the Lamont-Doherty Earth Observatory at Columbia University, 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 climate cyclicity close to 1470 ± 500 years in the North Atlantic 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. Later proponents of this view include S. Fred Singer of the University of Virginia and Dennis Avery of the Hudson Institute, an American think-tank. They suggest that the current global warming is a Bond or Dansgaard-Oeschger event, and is therefore natural and unstoppable. The North Atlantic ice-rafting events happen to correlate with most weak events of the Asian monsoon over the past 9,000 years, as well as with most aridification events in the Middle East. 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. See also: Error: Template must be given at least one article name 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 patterns of tides, variations in solar output, and "reorganizations of atmospheric circulation."
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