Global dimming and brightening

Abstract

A fundamental determinant of climate and life on our planet is the solar radiation (sunlight) incident at the Earth's surface. Any change in this precious energy source affects our habitats profoundly. Until recently, for simplicity and lack of better knowledge, the amount of solar radiation received at the Earth surface was assumed to be stable over the years. However, there is increasing observational evidence that this quantity undergoes significant multi-decadal variations, which need to taken into account in discussions of climate change and solar energy generation. Coherent periods and regions with prevailing declines (“dimming”) and inclines (“brightening”) in surface solar radiation have been detected in the worldwide observational networks, often in accord with anthropogenic air pollution patterns. This paper highlights the main characteristics of this phenomenon, and provides a conceptual framework for its causes as well as an overview over potential environmental implications.