Some features of climate change on Earth and its possible relation to solar-activity variations

Abstract

The global warming on Earth during the last century has been discussed in many studies. The most significant factors of climate change are the increase in the atmospheric concentration of greenhouse gases, catastrophic eruptions of volcanoes, and variations in the solar activity. In this paper, we consider the character of climate change and its possible relation to solar-activity variations using the data of the global network of meteorological stations on temperature variations in different regions across the globe from 1880 and information about variations in the relative sunspot number over the last 300 years and temporal variations in the total solar irradiation. We found that the annual mean sunspot number increased on average by about 0.2% per year in both 11-year and secular cycles. The increase in the globally averaged surface air temperature in the period 1880–2004 was Δt = 0.61 ± 0.04 °C. The difference in Δt calculated for periods with different solar-activity levels in 11-year cycles was estimated. This difference was most clearly revealed over land at high latitudes of the northern hemisphere. The medians of the distributions of the annual mean surface air temperature over land, ocean, and over the entire globe in years with high solar activity in the secular cycle are significantly greater than the corresponding values related to the years of low solar activity. Noticeable falls in temperature (by ∼0.1–0.2°C) through ∼1900–1920 and 1945–1980 are likely to be associated with the radiation balance perturbation caused by a large number of catastrophic volcanic eruptions during these periods. A considerable warming during the last three decades is most probably due to the substantial growth in the rate of carbon dioxide input to the atmosphere and the corresponding large increase in its concentration. The importance of this factor of global warming becomes even greater if we bear in mind that the solar activity in the secular cycle declines after 1970.