Heliogeophysical Features and Viral Epidemics of the 21st Century

Heliogeophysical features of the 21st century are considered. It is discussed that the low solar dynamics of cycles 24 and 25 manifested themselves not only in sunspot number, but also as a significant decrease in geomagnetic events, decreased intensity of solar cosmic rays, and increased intensity of galactic cosmic rays. Changes in the solar GMF and a significant decrease in the amplitude of odd harmonics of the global magnetic field (GMF) of the Sun were also observed. It is proposed to use the maximum of the fifth zonal harmonic of the solar GMF as a predictor of the time of the maximum of the 11-year solar activity cycle, and the polar field of the Sun to predict the height of the cycle. The maximum of the 25th cycle of solar activity (SA) predicted by the authors was expected at the end of 2023–beginning of 2024 with a cycle height of no more than 131. A secondary solar activity maximum is possible during 2025. Epidemiological processes can serve as an additional predictor of global changes in solar activity. The number of viral pandemics during the 19th–21st centuries was tripled near centennial solar activity minima. Measles epidemics are developing approximately a year prior to the onset of extrema of the 11-year solar activity cycle. It is emphasized that the role of solar activity minima in the development of viral epidemics is significantly underestimated.