LETTER


Harmonic Analysis of Worldwide Temperature Proxies for 2000 Years



Horst-Joachim Lüdecke1, *, Carl-Otto Weiss2
1 HTW, University of Applied Sciences, Saarbrücken, Germany
2 CINVESTAV, Querétaro, Mexico; visiting from PTB Braunschweig, Mexico, Germany


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© 2017 Lüdecke and Weiss.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the HTW, University of Applied Sciences, Saarbrücken, Germany, Tel: 0049-6221-781052; E-mail: moluedecke@t-online.de


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 14C and 10Be, 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.

Keywords: Worldwide temperature proxies, Solar-climate cycles, Solar origin of the ~190 year climate cycle with new accuracy.