Bond event
Encyclopedia
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
. 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
Gerard C. Bond
Gerard Clark Bond was a widely and highly respected American geologist. Bond received his Bachelor of Science degree at Capital University in Columbus, Ohio, where his father Ralph Bond was a Professor of Geology...
of the Lamont-Doherty Earth Observatory
Lamont-Doherty Earth Observatory
The Lamont–Doherty Earth Observatory is a research unit of Columbia University located on a campus in Palisades, N.Y., north of Manhattan on the Hudson River.- History :...
at Columbia University
Columbia University
Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...
, was the lead author of the paper published in 1997 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 core
Ice core
An ice core is a core sample that is typically removed from an ice sheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere. As the ice forms from the incremental build up of annual layers of snow, lower layers are older than upper, and an ice...
s. Less well established is the continuation of these cycles into the holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
. 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
Little Ice Age
The Little Ice Age was a period of cooling that occurred after the Medieval Warm Period . While not a true ice age, the term was introduced into the scientific literature by François E. Matthes in 1939...
, the 8.2 kiloyear event
8.2 kiloyear event
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...
, and the start of the Younger Dryas
Younger Dryas
The Younger Dryas stadial, also referred to as the Big Freeze, was a geologically brief period of cold climatic conditions and drought between approximately 12.8 and 11.5 ka BP, or 12,800 and 11,500 years before present...
.
The North Atlantic ice-rafting events happen to correlate with most weak events of the Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
n monsoon
Monsoon
Monsoon is traditionally defined as a seasonal reversing wind accompanied by corresponding changes in precipitation, but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with the asymmetric heating of land and sea...
over the past 9,000 years, as well as with most aridification events in the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far 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.
The hypothesis holds that the 1,500-year cycle displays nonlinear behavior
Nonlinearity
In mathematics, a nonlinear system is one that does not satisfy the superposition principle, or one whose output is not directly proportional to its input; a linear system fulfills these conditions. In other words, a nonlinear system is any problem where the variable to be solved for cannot be...
and stochastic resonance
Stochastic resonance
Stochastic resonance is a phenomenon that occurs in a threshold measurement system when an appropriate measure of information transfer is maximized in the presence of a non-zero level of stochastic input noise thereby lowering the response...
; 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 of Bond events
Most Bond events do not have a clear climate signal; some correspond to periods of cooling, others are coincident with aridification in some regions.- ≈1,400 BPBefore PresentBefore Present years is a time scale used in archaeology, geology, and other scientific disciplines to specify when events in the past occurred. Because the "present" time changes, standard practice is to use AD 1950 as the origin of the age scale, reflecting the fact that radiocarbon...
(Bond event 1) - ≈2,800 BP (Bond event 2) — correlates with an early 1st millennium BC1st millennium BCThe 1st millennium BC encompasses the Iron Age and sees the rise of many successive empires, and spanned from 1000 BC to 1 BC.The Neo-Assyrian Empire, followed by the Achaemenids. In Greece, Classical Antiquity begins with the colonization of Magna Graecia and peaks with the rise of Hellenism. The...
drought in the Eastern MediterraneanEastern MediterraneanThe Eastern Mediterranean is a term that denotes the countries geographically to the east of the Mediterranean Sea. This region is also known as Greater Syria or the Levant....
, possibly triggering the collapse of Late Bronze Age culturesBronze Age collapseThe Bronze Age collapse is a transition in southwestern Asia and the Eastern Mediterranean from the Late Bronze Age to the Early Iron Age that some historians believe was violent, sudden and culturally disruptive...
. - ≈4,200 BP4.2 kiloyear eventThe 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 ≈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...
(Bond event 3) — correlates also with the collapse of the Akkadian Empire and the end of the Egyptian Old KingdomOld KingdomOld Kingdom is the name given to the period in the 3rd millennium BC when Egypt attained its first continuous peak of civilization in complexity and achievement – the first of three so-called "Kingdom" periods, which mark the high points of civilization in the lower Nile Valley .The term itself was...
. - ≈5,900 BP5.9 kiloyear eventThe 5.9 kiloyear event was one of the most intense aridification events during the Holocene. It occurred around 3900 BC, ending the Neolithic Subpluvial and probably initiated the most recent desiccation of the Sahara desert. Thus, it also triggered worldwide migration to river valleys, e.g...
(Bond event 4) — correlates with the end of the Pre-Pottery Neolithic BPre-Pottery Neolithic BPre-Pottery Neolithic B is a division of the Neolithic developed by Dame Kathleen Kenyon during her archaeological excavations at Jericho in the southern Levant region....
, and the arrival of nomadic pastoralists in the Middle East. - ≈8,100 BP8.2 kiloyear eventThe 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...
(Bond event 5) - ≈9,400 BP (Bond event 6) — correlates with the Erdalen event of glacierGlacierA glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...
activity in NorwayNorwayNorway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
, as well as with a cold event in China. - ≈10,300 BP (Bond event 7)
- ≈11,100 BP (Bond event 8) — coincides with the transition from the Younger DryasYounger DryasThe Younger Dryas stadial, also referred to as the Big Freeze, was a geologically brief period of cold climatic conditions and drought between approximately 12.8 and 11.5 ka BP, or 12,800 and 11,500 years before present...
to the borealBoreal (period)In paleoclimatology of the Holocene, the Boreal was the first of the Blytt-Sernander sequence of north European climatic phases that were originally based on the study of Danish peat bogs, named for Axel Blytt and Rutger Sernander, who first established the sequence. In peat bog sediments, the...
.