The results of analyzing the paleodata on solar activity variations (variations of cosmogenic ¹⁴ C and ¹⁰ Be isotopes in the terrestrial records, such as glaciers, tree rings, sea-floor marine and lacustrine sediments, loess, etc.), the paleomagnetic and archeomagnetic data, as well as the paleoclimatic data, prove that the flows of galactic cosmic rays, modulated by heliomagnetic and geomagnetic fields, affect the climate of the Earth. In this study we analyzed different periods of time, namely, the last millennium, the Holocene epoch (up to 10-12 thousand years ago), and the time interval of 10-50 thousand years ago. Our analysis suggested that the variations of the cosmic ray fluxes seemed to be the most effective factor responsible for long-term climate variations.