Bond events are

North Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for ...

ice rafting events that Gerard C. Bond sought to link to climate fluctuations in the

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

. Eight such events have been identified. Bond events were previously believed to exhibit a roughly cycle, but the primary period of variability is now put at . Gerard C. Bond of the

Lamont–Doherty Earth Observatory The Lamont-Doherty Earth Observatory (LDEO) is a research, research institution specializing in the Earth science and climate change. Though part of Columbia University, it is located on a separate closed campus in Palisades, New York. The obs ...

, at

Columbia University Columbia University in the City of New York, commonly referred to as Columbia University, is a Private university, private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of Trinity Churc ...

, was the lead author of the 1997 paper that postulated the theory of 1470-year climate cycles in the

Late Pleistocene The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as the Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division ...

and the Holocene, mainly based on

petrologic Petrology () is the branch of geology that studies rock (geology), rocks, their mineralogy, composition, texture, structure and the conditions under which they form. Petrology has three subdivisions: igneous petrology, igneous, metamorphic rock, ...

tracers of

drift ice Drift or Drifts may refer to: Geography * Drift or ford (crossing) of a river * Drift (navigation), difference between heading and course of a vessel * Drift, Kentucky, unincorporated community in the United States * In Cornwall, England: ** D ...

in the

. However, more recent work at a single site suggested that the tracers did not provide sufficient support for 1,500-year intervals of climate change and suggested that the reported period was a statistical artifact. Furthermore, after the publication of the Greenland Ice Core Chronology 2005 (GICC05) for the

North Greenland Ice Core Project The drilling site of the North Greenland Ice Core Project (NGRIP or NorthGRIP) is near the center of Greenland (75.1 N, 42.32 W, 2917 m, ice thickness 3085). Drilling began in 1999 and was completed at bedrock in 2003. The ice core, cores are ...

ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier ...

, it became clear that Dansgaard–Oeschger events also show no such pattern. The North Atlantic ice-rafting events happen to correlate with episodes of lowered lake levels in the Mid-Atlantic region of the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, the weakest events of the Asian

monsoon A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in Atmosphere of Earth, atmospheric circulation and precipitation associated with annu ...

for at least the past 9,000 years and also with most

aridification Aridification is the process of a region becoming increasingly arid, or dry. It refers to long term change, rather than seasonal variation. It is often measured as the reduction of average soil moisture content. It can be caused by reduced preci ...

events in the

Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...

for the past 55,000 years (both Heinrich and Bond events).

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. Gaps between events havw been estimated to be 1,000-1,500 years, with Bond event # 4 as an outlying data point.

Influence in regional climate

Bond events have been detected in remote regions such as the central

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. Up to six Bond cycles during the upper and middle

have been identified in three ice core records of the tropical Andes. The records were extracted from the summits of

Nevado Sajama Nevado Sajama (; ) is an extinct volcano and the highest peak in Bolivia. The mountain is located in Sajama Province, in Oruro Department. It is situated in Sajama National Park and is a composite volcano consisting of a stratovolcano on top of ...

, Nevado Huascarán, and Nevado Illimani. The detected cycles were at 6400 years

Before Present Before Present (BP) or "years before present (YBP)" is a time scale used mainly in archaeology, geology, and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Because ...

(BP), 5500 years BP, 3700 years BP, 2700 years BP, 1300 years BP, and 200 years BP and represented temperature drops.

References

{{Global warming Atlantic Ocean History of climate variability and change

List

Influence in regional climate

See also

References