Contribution of changing galactic cosmic ray flux to global warming

Abstract

The well established excellent correlation between low-level clouds and primary cosmic ray intensity, which act as nuclei for cloud condensation, clearly shows that a decrease in primary cosmic ray intensity results in lesser low cloud cover. Reduced albedo radiation reflected back into space, due to lesser low cloud cover, results in an increase in the surface temperature on the earth. Extrapolation of the intensity of galactic cosmic radiation using ¹⁰Be measurements in deep polar ice as the proxy, clearly shows that the primary cosmic ray intensity has decreased by 9% during the last 150 years, due to the continuing increase in solar activity. We present evidence to show that the radiative forcing component due to the decrease in primary cosmic ray intensity during the last 150 years is 1.1 Wm⁻², which is about 60% of that due to CO₂ increase. We conclude that the future prediction of global warming presented by IPCC4 requires a relook to take into the effect due to long-term changes in the galactic cosmic ray intensity.