There are a number of paleoclimatic papers that note there is a correlation with C14 and other cosmogenic isotopes changes and abrupt climatic change. For example Gerald Bond’s, "Persistent Solar Influence on North Atlantic Climate During the Holocene."
http://www.essc.psu.edu/essc_web/sem...0al%202001.pdf
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…The evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon-14 and beryllium-10 and centennial to millennial time scale changes in proxies of drift ice measured in deep-sea sediment cores. A solar forcing mechanism therefore may underlie at least the Holocene segment of the North Atlantic’s 1500-year cycle…
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Another example is this paper which discusses the cause of the 11,200 year ago abrupt climatic change (The 11,200 year ago climate change is called the Younger Dryas. Named after a tundra flower, "Younger Dryas" that suddenly appears in the Northern Hemisphere in regions that are currently covered by forests). The YD climatic event interrupted the current Holocene interglacial returning the planet back to the glacial phase. The Greenland Ice sheet data shows the YD change occurred in less than a decade.
“Reduced solar activity as a trigger for the start of the Younger Dryas?”
http://www.geo.vu.nl/~renh/pdf/Renssen-etal-QI-2000.pdf
From the paper:
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“Estimates for the start of the YD all demonstrate a strong and rapid rise of C14 (Cosmogenic isotope that increases when there is decreased solar activity that hence allows increased galactic cosmic rays GCR to strike and interact with the atmosphere.) This change is the largest increase of atmospheric C14 known from the late glacial period and Holocene records.”
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As to what could possibly be causing a semi periodic solar magnetic field change, a number of papers have been written concerning an observed correlation of solar inertial motion and the solar magnetic changes.
For example:
Prolonged minima and the 179-yr cycle of the solar inertial motion by R.Fairbridge and J. Shirley
http://www.springerlink.com/content/w57236105034h657/
This paper, “Can origin of the 2400-year cycle of solar activity be caused by solar inertial motion?” provides a full explanation of the solar mechanisms and a summary of previous papers concerning solar inertial motion and solar magnetic cycle changes.
http://www.ann-geophys.net/20/115/20...0-115-2002.pdf
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...Time comparison of the epochs of high and low solar activity with climate alteration led to the conclusion that the cause of the approx. 2400-year cycle, both in the 14C concentration and in climate of the Earth, appears to be of a solar nature (Dergachev and Chistyakov, 1995)…
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…The first basic cycle of solar inertial motion, the cycle of 178.7 years, was found by Jose (1965) in a repetition of solar motion characteristics computed between 1653 and 2060, and most important the time derivative of the Sun's angular momentum was found…
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