The Role of Clouds, Aerosols and Galactic Cosmic Rays in Climate Change

Abstract

A review of the role played by clouds, by natural and anthropogenic aerosols and by their interaction, on climate, is presented. The suggestion that galactic cosmic rays may affect the interaction between clouds/aerosols and climate is here discussed in the context of the CLOUD (Cosmics Leaving Outdoor Droplets) experiment at CERN. The experiment has shown that cosmic rays enhance aerosol nucleation and cloud condensation but the effect is too weak to have an impact on climate during a solar cycle or over the last century. The CLOUD experiment has also revealed a nucleation mechanism involving the formation of clusters containing sulphuric acid and oxidized organic molecules.