Harmonic Analysis of Worldwide Temperature Proxies for 2000 Years

Abstract

Abstract:The Sun as climate driver is repeatedly discussed in the literature but proofs are often weak. In order to elucidate the solar influence, we have used a large number of temperature proxies worldwide to construct a global temperature mean G7 over the last 2000 years. The Fourier spectrum of G7 shows the strongest components as ~1000-, ~460-, and ~190 -year periods whereas other cycles of the individual proxies are considerably weaker. The G7 temperature extrema coincide with the Roman, medieval, and present optima as well as the well-known minimum of AD 1450 during the Little Ice Age. We have constructed by reverse Fourier transform a representation of G7 using only these three sine functions, which shows a remarkable Pearson correlation of 0.84 with the 31-year running average of G7. The three cycles are also found dominant in the production rates of the solar-induced cosmogenic nuclides 14 C and 10 Be, most strongly in the ~190 -year period being known as the De Vries/Suess cycle. By wavelet analysis, a new proof has been provided that at least the ~190-year climate cycle has a solar origin.

On Time Scales of Intrinsic Oscillations in the Climate System

“…Figure 1 shows an example of the SFA analysis for record 5 of Table 1 ; here, this analysis identifies significant oscillations with central periods of 187, 485, and 970 years. These are closely similar to periods 188, 463 and 1003 years found in [ 14 ] using Fourier analysis. The analogous results for other records are shown in the Supplementary material (Figures S4–S14) .…”

Using Oscillatory Processes in Northern Hemisphere Proxy Temperature Records to Forecast Industrial-era Temperatures

“…These results are in good agreement with a study [18] reporting a harmonic analysis of worldwide temperature proxies for 2,000 years incorporating six previous global proxy temperature records. This showed the strongest components as sine waves with periodicities of ~1,000 years, ~460 years, and ~190 years, whereas other oscillations of the individual proxies are considerably weaker Another investigation [51] undertook wavelet analysis showing the dominant periodic variations of 1,130, 790-770, 560 and 390-360 years for Greenland ice core records extending over a period of 4,000 years.…”

“…Identification of continuing oscillatory patterns can potentially be valuable in forecasting temperatures. A number of studies have found evidence for oscillations in proxy records at millennial, centennial and decadal time scales by applying spectral analysis [18][19][20]. It has been suggested that some proxy records may not include low frequency oscillations because certain types of proxy (particularly tree rings) do not capture this compared to others proxies such as ice cores.…”

“…However, it may not be evident whether these are random oscillations or the combined effects of underlying sets of oscillations with persistent periodicities, amplitudes and phase relationships. The presence of persistent, defined oscillations has been found in both instrumental and proxy temperature records using spectral analysis [18]. For example, in an examination of tree-ring records over 1,300 years for the Gulf of Alaska [20] several multi-decadal oscillations were identified applying spectral analysis.…”

“…These can be compared with the range of millennial periodicities (978 -1,306 years) identified in the present study. Global ~1000 [18] Millennial-scale climatic oscillations of ~1,470 years are evident in numerous palaeo-climatic records in the North Atlantic and Pacific [67 -71]. A study [72] discussed the existence of a ~ 1,470 year cycle in the context of climate change.…”