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Solar-Powered Millennial-Scale Climatic Change
Volume 9, Number 1: 4 January 2006

Many palaeoclimate records from earth's North Atlantic region depict a millennial-scale oscillation of climate, which during the last glacial period was highlighted by Dansgaard-Oeschger events that regularly recurred at approximately 1,470-year intervals (Rahmstorf, 2003).  Because of the consistency of their occurrence, it was long believed that these well-tuned periodic events were orchestrated by similarly-paced solar activity; but a major problem with this idea was that no known solar process or orbital perturbation exhibited the periodicity of the Dansgaard-Oeschger events.  Now, however, Braun et al. (2005) have performed an analysis that successfully explains this dichotomy.

Noting that the periods of the well-known DeVries-Suess and Gleissberg solar cycles (~210 and 87 years, respectively) are close to prime factors of 1,470 years, the team of eight German scientists opined that "the superposition of two such frequencies could result in variability that repeats with a 1,470-year period."  In fact, they did more than opine about the matter; they proceeded to show, in their words, that "an intermediate-complexity climate model with glacial climate conditions simulates rapid climate shifts similar to the Dansgaard-Oeschger events with a spacing of 1,470 years when forced by periodic freshwater input into the North Atlantic ocean in cycles of ~86 and ~210 years."  The researchers' goal in this exercise was "not aimed at suggesting a certain mechanism for solar influence on freshwater fluxes," as they describe it, but merely to demonstrate that "the glacial 1,470-year climate cycles could have been triggered by solar forcing despite the absence of a 1,470-year solar cycle," which objective they admirably achieved.

For the same reason, and also without specifying a particular mechanism, Braun et al.'s exercise suggests that the similarly-paced millennial-scale oscillation of climate that has reverberated throughout the Holocene (but with less perfect regularity) is also driven by the combinatorial effect of the DeVries-Suess and Gleissberg solar cycles.  In fact, the German scientists say that the stimulus for their idea that "a multi-century climate cycle might be linked with century-scale solar variability comes from Holocene data," citing the work of Bond et al. (2001), who found that "over the last 12,000 years virtually every centennial time-scale increase in drift ice documented in our North Atlantic records was tied to a solar minimum," and who concluded that "a solar influence on climate of the magnitude and consistency implied by our evidence could not have been confined to the North Atlantic," suggesting that the cyclical climatic effects of the variable solar inferno are experienced throughout the entire world.

What are some of the better-known climatic manifestations of this cyclical solar-powered phenomenon?  Bond et al. report that the climatic oscillation's most recent cold node and the warm node that preceded it were "broadly correlative with the so called 'Little Ice Age' and 'Medieval Warm Period'."  Likewise, Rahmstorf states that "the so-called 'little ice age' of the 16th-18th century may be the most recent cold phase of this cycle."

The final logical extension of these observations should be obvious to all: the global warming of the past century or so, which propelled the earth out of the Little Ice Age and into the Current Warm Period, was in all likelihood a result of the most recent upswing in this continuing cycle of solar-induced climate change.  Hence, there is no longer any need to consider the historical rise in the atmosphere's CO2 concentration as being the primary driver of 20th-century warming.  Like everything else climate alarmists lump along with it, the much-maligned greenhouse gas was merely "along for the ride" on earth's eternally-oscillating climatic roller coaster whose operator is the sun.

Sherwood, Keith and Craig Idso

Bond, G., Kromer, B., Beer, J., Muscheler, R., Evans, M.N., Showers, W., Hoffmann, S., Lotti-Bond, R., Hajdas, I. and Bonani, G.  2001.  Persistent solar influence on North Atlantic climate during the Holocene.  Science 294: 2130-2136.

Braun, H., Christl, M., Rahmstorf, S., Ganopolski, A., Mangini, A., Kubatzki, C., Roth, K. and Kromer, B.  2005.  Possible solar origin of the 1,470-year glacial climate cycle demonstrated in a coupled model.  Nature 438: 208-211.

Rahmstorf, S.  2003.  Timing of abrupt climate change: A precise clock.  Geophysical Research Letters 30: 10.1029/2003GL017115.