Monday, 10 January 2005
From Dimming to Brightening: Trends in Solar Radiation inferred from Surface Observations
Variations in solar radiation incident at the Earth’s surface profoundly affect the human and terrestrial environment. Newly available surface observations from 1990 to present show that the decline of solar radiation at land surfaces found in earlier studies and known as global dimming fades in the 1990s. Rather, trends become positive since the late 1980s. The trend reversal is reconcilable with recently estimated trends in Earth reflectance, cloudiness and atmospheric transmission and may substantially affect surface climate, hydrology and ecosystems. Solar radiation decline may thus have no longer masked the enhanced greenhouse effect, resulting in the accelerated temperature increase observed during the 1990s.