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5.9 Kiloyear Event
Bond events are North Atlantic ice rafting events that are tentatively linked to climate fluctuations in the Holocene. 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 at Columbia University was the lead author of the 1997 paper that postulated the theory of 1470-year climate cycles in the Late Pleistocene and Holocene, mainly based on petrologic tracers of drift ice in the North Atlantic. However, more recent work has shown that these tracers provide little support for 1,500-year intervals of climate change, and the reported period was a statistical artifact. Furthermore, following publication of the Greenland Ice Core Chronology 2005 (GICC05) for the North GRIP ice core, it became clear that Dansgaard–Oeschger events also show no such pattern. The North Atlantic ice-rafting events happen to correlate with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holocene Temperature Variations
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch, called the Flandrian interglacial.Oxford University Press – Why Geography Matters: More Than Ever (book) – "Holocene Humanity" section https://books.google.com/books?id=7P0_sWIcBNsC The Holocene corresponds with the rapid proliferation, growth and impacts of the human species worldwide, including all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of global signi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heinrich Event
A Heinrich event is a natural phenomenon in which large groups of icebergs break off from glaciers and traverse the North Atlantic. First described by marine geologist Hartmut Heinrich (Heinrich, H., 1988), they occurred during five of the last seven glacial periods over the past 640,000 years (Hodell, et al., 2008). Heinrich events are particularly well documented for the Wisconsin glaciation, last glacial period but notably absent from the Penultimate Glacial Period, penultimate glaciation (Obrochta et al., 2014). The icebergs contained rock mass that had been eroded by the glaciers, and as they melted, this material was dropped to the sea floor as ice rafted debris (abbreviated to "IRD") forming deposits called Heinrich layers. The icebergs' melting caused vast quantities of fresh water to be added to the North Atlantic. Such inputs of cold and fresh water may well have altered the density-driven, thermohaline circulation patterns of the ocean, and often coincide with indicatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sahara
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Old Kingdom Of Egypt
In ancient Egyptian history, the Old Kingdom is the period spanning c. 2700–2200 BC. It is also known as the "Age of the Pyramids" or the "Age of the Pyramid Builders", as it encompasses the reigns of the great pyramid-builders of the Fourth Dynasty, such as King Sneferu, who perfected the art of pyramid-building, and the kings Khufu, Khafre and Menkaure, who constructed the pyramids at Giza. Egypt attained its first sustained peak of civilization during the Old Kingdom, the first of three so-called "Kingdom" periods (followed by the Middle Kingdom and New Kingdom), which mark the high points of civilization in the lower Nile Valley. The concept of an "Old Kingdom" as one of three "golden ages" was coined in 1845 by the German Egyptologist Baron von Bunsen, and its definition would evolve significantly throughout the 19th and the 20th centuries. Not only was the last king of the Early Dynastic Period related to the first two kings of the Old Kingdom, but the "capi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Akkadian Empire
The Akkadian Empire () was the first ancient empire of Mesopotamia after the long-lived civilization of Sumer. It was centered in the city of Akkad () and its surrounding region. The empire united Akkadian and Sumerian speakers under one rule. The Akkadian Empire exercised influence across Mesopotamia, the Levant, and Anatolia, sending military expeditions as far south as Dilmun and Magan (modern Saudi Arabia, Bahrain, and Oman) in the Arabian Peninsula.Mish, Frederick C., Editor in Chief. "Akkad" ''Webster’s Ninth New Collegiate Dictionary''. ninth ed. Springfield, MA: Merriam-Webster 1985. ). The Akkadian Empire reached its political peak between the 24th and 22nd centuries BC, following the conquests by its founder Sargon of Akkad. Under Sargon and his successors, the Akkadian language was briefly imposed on neighboring conquered states such as Elam and Gutium. Akkad is sometimes regarded as the first empire in history, though the meaning of this term is not p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron Age Cold Epoch
The Iron Age Cold Epoch (also referred to as Iron Age climate pessimum or Iron Age neoglaciation) was a period of unusually cold climate in the North Atlantic region, lasting from about 900 BC to about 300 BC, with an especially cold wave in 450 BC during the expansion of ancient Greece. It was followed by the Roman Warm Period (250 BC – 400 AD). Gill Plunkett and Graeme T. Swindles of Queen's University Belfast , mottoeng = For so much, what shall we give back? , top_free_label = , top_free = , top_free_label1 = , top_free1 = , top_free_label2 = , top_free2 = , established = , closed = , type = Public research university , parent = ... used volcanic ash layers and radiocarbon dating to constrain the start of Iron Age climate deterioration in Ireland to 750 BC. References * * * * History of climate variability and change Iron Age Holocene {{climate-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Antique Little Ice Age
The Late Antique Little Ice Age (LALIA) was a long-lasting Northern Hemispheric cooling period in the 6th and 7th centuries AD, during the period known as Late Antiquity. The period coincides with three large volcanic eruptions in 535/536, 539/540 and 547. The volcanic winter of 536 was the early phenomenon of the century-long global temperature decline. One study suggested a global cooling of . Eruptions The existence of a cooling period was proposed as a theory in 2015, and subsequently confirmed as the period from 536 to about 660 CE. Volcanic eruptions, meteorites striking the earth's surface, and comet fragments exploding in the upper atmosphere have been proposed for the climatic cooling in 536 and afterwards. A problem is that no impact crater for a meteorite has been found, even though the land area and sea beds have been well surveyed for evidence. A comet fragment half a kilometer in size exploding in the atmosphere could cause a plume of debris on the earth and crea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Migration Period
The Migration Period was a period in European history marked by large-scale migrations that saw the fall of the Western Roman Empire and subsequent settlement of its former territories by various tribes, and the establishment of the post-Roman kingdoms. The term refers to the important role played by the migration, invasion, and settlement of various tribes, notably the Franks, Goths, Alemanni, Alans, Huns, early Slavs, Pannonian Avars, Magyars, and Bulgars within or into the former Western Empire and Eastern Europe. The period is traditionally taken to have begun in AD 375 (possibly as early as 300) and ended in 568. Various factors contributed to this phenomenon of migration and invasion, and their role and significance are still widely discussed. Historians differ as to the dates for the beginning and ending of the Migration Period. The beginning of the period is widely regarded as the invasion of Europe by the Huns from Asia in about 375 and the ending with the co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Little Ice Age
The Little Ice Age (LIA) was a period of regional cooling, particularly pronounced in the North Atlantic region. It was not a true ice age of global extent. The term was introduced into scientific literature by François E. Matthes in 1939. Matthes described glaciers in the Sierra Nevada of California that he believed could not have survived the hypsithermal; his usage of "Little Ice Age" has been superseded by " Neoglaciation". The period has been conventionally defined as extending from the 16th to the 19th centuries, (noted in Grove 2004:4). but some experts prefer an alternative timespan from about 1300 to about 1850. The NASA Earth Observatory notes three particularly cold intervals. One began about 1650, another about 1770, and the last in 1850, all of which were separated by intervals of slight warming. The Intergovernmental Panel on Climate Change Third Assessment Report considered that the timing and the areas affected by the Little Ice Age suggested largely independ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kiloannus
A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked. A calendar year is an approximation of the number of days of the Earth's orbital period, as counted in a given calendar. The Gregorian calendar, or modern calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars. For the Gregorian calendar, the average length of the calendar year (the mean yea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anno Domini
The terms (AD) and before Christ (BC) are used to label or number years in the Julian and Gregorian calendars. The term is Medieval Latin and means 'in the year of the Lord', but is often presented using "our Lord" instead of "the Lord", taken from the full original phrase "''anno Domini nostri Jesu Christi''", which translates to 'in the year of our Lord Jesus Christ'. The form "BC" is specific to English and equivalent abbreviations are used in other languages: the Latin form is but is rarely seen. This calendar era is based on the traditionally reckoned year of the conception or birth of Jesus, ''AD'' counting years from the start of this epoch and ''BC'' denoting years before the start of the era. There is no year zero in this scheme; thus ''the year AD 1 immediately follows the year 1 BC''. This dating system was devised in 525 by Dionysius Exiguus, but was not widely used until the 9th century. Traditionally, English follows Latin usage by placing the "AD" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Before Present
Before Present (BP) years, or "years before present", 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 the "present" time changes, standard practice is to use 1 January 1950 as the commencement date (epoch) of the age scale. The abbreviation "BP" has been interpreted retrospectively as "Before Physics", which refers to the time before nuclear weapons testing artificially altered the proportion of the carbon isotopes in the atmosphere, which scientists must now account for. In a convention that is not always observed, many sources restrict the use of BP dates to those produced with radiocarbon dating; the alternative notation RCYBP stands for the explicit "radio carbon years before present". Usage The BP scale is sometimes used for dates established by means other than radiocarbon dating, such as stratigraphy. This usage differs fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
