We carried out wavelet and correlation analysis in the range of periods of 20–70 years of the following instrumental data series: the number of sunspots in 1700–2020, on the one hand, and the average global temperature and Earth rotation rate, as well as the and components of the geomagnetic field measured in magnetic observatories starting from the end of the 19th century, on the other hand. It was obtained that over the past ~150–170 years, ~40-year and ~20-year variations have been observed in the wavelet spectra. In all spectra of geophysical data at this time, 60–70-year variation dominates, in addition, fluctuations with periods from ~20 to ~40 years appear in different time intervals. The rotation rate correlates with the temperature at the level of 0.8 and both processes are almost the same in phase. Their main common period is 69 years. The identified ~60–70-year variations in the spectra of the geomagnetic field are caused by changes in internal sources in the Earth’s liquid core. Our results suggest that the influence of solar activity does not manifest itself in ~60–70 year changes in the magnetic field components, as well as in the temperature of the Earth. At the same time, solar activity appears to be able to contribute directly to temperature changes with periods of ~35 years; the correlation coefficient of the and temperature spectra in this period range was ≈0.5.
N.G. Ptitsyna (Wed,) studied this question.