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A climate oscillation or climate cycle is any recurring cyclical oscillation within global or regional climate, and is a type of climate pattern. These fluctuations in atmospheric temperature, sea surface temperature, precipitation or other parameters can be quasi-periodic, often occurring on inter-annual, multi-annual, decadal, multidecadal, century-wide, millennial or longer timescales. They are not perfectly periodic and a Fourier analysis of the data does not give a sharp spectrum. A prominent example is the El Niño Southern Oscillation, involving sea surface temperatures along a stretch of the equatorial Central and East Pacific Ocean and the western coast of tropical South America, but which affects climate worldwide. Records of past climate conditions are recovered through geological examination of proxies, found in glacier ice, sea bed sediment, tree ring studies or otherwise. ==Examples== Many oscillations on different time-scales are hypothesized, although the causes may be unknown. (Some of them are more like a random walk than an oscillation.) Here is a list of known or proposed climatic oscillations: * the glacial periods of the last ice age – period around 100 000 years (see Quaternary glaciation#Astronomical cycles and 100,000-year problem) * North African climate cycles – tens of thousands of years * the Atlantic Multidecadal Oscillation – around 50 to 70 years, but unpredictable * the El Niño Southern Oscillation – 2 to 7 years * the Pacific decadal oscillation – 8 to 12 years? (not clear) * the Interdecadal Pacific Oscillation – 15 to 30 years? (not clear) * the Arctic oscillation – no particular periodicity * the North Atlantic Oscillation – no particular periodicity * the North Pacific Oscillation – ? * the Hale cycle or sunspot cycle – about 11 years (may be discernible in climate records; see solar variation) * the Quasi-biennial oscillation – about 30 months * a 60-year climate cycle recorded in many ancient calendars〔 Anomalies in oscillations sometimes occur when they coincide, as in the Arctic dipole anomaly (a combination of the Arctic and North Atlantic oscillations) and the longer-term Younger Dryas, a sudden non-linear cooling event that occurred at the onset of the current Holocene interglacial. In the case of volcanoes, large eruptions such as Mount Tambora in 1816, which led to the Year Without a Summer, typically cool the climate, especially when the volcano is located in the tropics. Around 70 000 years ago the Toba supervolcano eruption created an especially cold period during the ice age, leading to a possible genetic bottleneck in human populations. However, outgassing from large igneous provinces such as the Permian Siberian Traps can input carbon dioxide into the atmosphere, warming the climate. Triggering of other mechanisms, such as methane clathrate deposits as during the Paleocene-Eocene Thermal Maximum, increased the rate of climatic temperature change and oceanic extinctions. Another longer-term near-millennial oscillation involves the Daansgard-Oeschger cycles, occurring on roughly 1,500-year cycles during the last glacial maximum. They may be related to the Holocene Bond events, and may involve factors similar to those responsible for Heinrich events. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Climate oscillation」の詳細全文を読む スポンサード リンク
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