Long-Term Variability of Summer Temperature in the Southern Part of South America—Is There a Connection with Changes in Solar Activity?

Abstract

Reconstruction of the summer (December–February) temperature of the southern part of the South American continent was studied in the time interval 900–1995. Significant temporal variations with periods of ca 520 years, ca 220 years, and 90–150 years have been found. Since bicentennial and century-type climatic oscillations can be a manifestation of the respective solar cycles of Suess and Gleissberg, the correlation between the corresponding climatic and solar periodicities was investigated. Data on the concentration of cosmogenic beryllium in the ice of the South Pole, solar modulation potential, and total solar irradiance, reconstructed using cosmogenic isotopes, were used as indicators of activity of the Sun. It turned out that there was no correlation between bicentennial and century-long variations in solar activity and temperature in the southern part of the South American continent. On the other hand, a fairly significant (c.l. 0.92–0.94) correlation between the multi-centennial (periods of 393–548 years) temperature variations and solar proxies was found. Based on these results, it is difficult to draw an unambiguous conclusion about the solar forcing on the climate of South America. It is more important that the results obtained confirm the existence of natural variations in the Earth’s climate with periods close to solar cycles but independent of changes in solar activity. The presence of such periodicities can seriously complicate the identification of the solar influence on the climate, which should be taken into account in further solar-climatic studies.