Radiocarbon dating is used for estimating the ages of

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by Javier Summary: Holocene climate has been affected in different periods by several centennial to millennial solar cycles. The 980-year solar cycle was named the Eddy cycle by Abreu et al. For about a millennium centered in each Bray cycle low, the de Vries cycle reduces solar activity every ~ 208 years, and when a cluster of GSM takes place, it establishes the average spacing between them (figure 61). The modulation of the de Vries cycle by the Bray cycle is also apparent in the climatic data. (2012) analyzed the ~ 200-year periodicity during the past two millennia using seventeen near worldwide distributed tree chronologies, and found significant periodicities in the 208-year frequency band, corresponding to the De Vries cycle of solar activity, indicating a solar contribution in the temperature and precipitation series.The ~ 1000-year Eddy solar cycle seems to have dominated Holocene climate variability between 11,500-4,000 years BP, and in the last two millennia, where it defines the Roman, Medieval, and Modern warm periods. (2010), and its lows have been numbered here, from more recent, as E1, E2, … The climatic effect of the Eddy cycle should manifest in the two periods when solar activity was most affected by this millennial periodicity. b) Sunspot based solar activity reconstruction from the radiocarbon record showing the disposition of the GSM associated with the Bray (blue) and Eddy (orange) cycle lows. Outside these windows centered in the Bray cycle lows, the de Vries periodicity has very low power in wavelet analysis indicating it has little effect on solar activity (figure 58). The result continued being significant after the removal of the volcanic signal, and was most prominent in records from Asia and Europe (figure 85; Breitenmoser et al., 2012).a) Solar sunspot number reconstruction from cosmogenic C isotopes. b) Wavelet analysis of the sunspot number reconstruction, with the Eddy periodicity indicated by a continuous line, and the Bray periodicity by a dashed line. a) Solar sunspot number reconstruction from cosmogenic C isotopes. Blue curve, inferred iceberg activity in the North Atlantic (inverted) from petrological tracers. Other researchers have found that applying the trapezoidal filter of Gleissberg separately to dates of solar cycle minima and maxima from sunspot records then merging them, one also obtains an ~ 80-year time domain periodicity (Peristykh & Damon, 2003).A regularly spaced 980-year periodicity is shown as arches above. c) Scale-averaged wavelet power for the 800-1200 years band (Eddy periodicity, continuous line, left scale), and the 1700-2800 years band (Bray periodicity, dashed line, right scale). A regularly spaced 980-year periodicity is shown as arches above. They interpret this result as confirmation of the cycle, that would simultaneously regulate the 11-year cycle amplitude and period.

Some of the cycles, like the ~ 2400-year Bray and the ~ 1000-year Eddy cycle, appear to be featured in records several million years old (Kern et al., 2012).

The ~ 208-year de Vries cycle has been detected in ice-cores for at least the past 50,000 years (Raspopov et al., 2008b).

Other periodicities however, like the 88-year Gleissberg cycle, have only been found for a few millennia.

Wavelet analysis shows the ~ 1000-year periodicity having a strong signal between 11,500 and 4,000 yr BP, and between 2,000 and 0 yr BP, but a very low signal between 4,000 and 2,000 yr BP (figure 79; Ma 2007; Kern et al., 2012). Several authors have noticed this solar forcing dominance during the early Holocene (figure 41; Debret et al., 2007; Simonneau et al., 2014). b) Holocene record of North Atlantic iceberg activity determined by the presence of drift-ice petrological tracers. When the amplitude of the 1000-year solar signal is adjusted by its wavelet power (figure 81), a high correlation between North Atlantic iceberg activity and the 980-year Eddy solar cycle corresponds to the periods when the 1000-year solar signal is high, while the correlation is low at periods of weak 1000-year solar signal, strengthening the relationship between climatic Bond events and solar activity, that has been acknowledged by multiple authors, starting with Gerald Bond himself (Bond et al., 2001). Black curve, a 1000-year frequency cycle representing solar activity for that periodicity, whose amplitude reflects the relative power (colored bar) of that frequency in a solar activity reconstruction wavelet analysis. Two of these GSM, at 10,165 and 5,275 years BP, also coincide with the Eddy cycle, as both cycles tend to coincide in phase when two Bray cycles (4,950 years), and five Eddy cycles (4,900 years) have passed. The name refers in some cases to a GSM cluster (cl.). As originally described, the Gleissberg cycle is unacceptable by modern scientific standards (and I would dare to say inexistent), and due to it the term Gleissberg cycle means different things to different authors.

The average duration of the ~ 1000-year cycle can be calculated from the grand solar minimum at 11,115 yr BP to the one at 1,265 yr BP (dates from Usoskin et al., 2016) for ten periods at 985 years, a span in very good agreement with the calculated 970 years from frequency analysis (Kern et al., 2012) and the calculated 983.4 years from astronomical cycles (Scafetta, 2012). The 980-year Eddy cycle in solar activity reconstructions. The Bond series of North Atlantic drift-ice record reflects a clear ~ 1000-year periodicity during the first 6,500 years of the Holocene that correlates with the 980-year Eddy solar cycle (figures 48 & 80; Debret et al., 2007). The 980-year Eddy cycle correspondence to Bond events. The unusually long Roman Warm Period (2500-1600 BP; Wang et al., 2012) coincided with the final part of this interval of low Eddy solar cycle activity, while known warm and cold periods have faithfully followed the since strengthened 980-year Eddy solar cycle (figure 81). North Atlantic iceberg activity and the Eddy solar cycle. The cycle states if the GSM shows a temporal coincidence with a low from the Bray (B), or Eddy (E) cycle. For some authors it is a frequency peak of ~ 88 years that appears in frequency analysis of the cosmogenic record (Mc Cracken et al., 2013b; Knudsen et al., 2011; figure 86).

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