ABSTRACT
Global dimming is a term describing the reduction in incoming sunlight (or insolation) reaching the earth’s surface in the last 50 years. Studies of sunlight data show that insolation reaching the earth’s surface decreased by around 5% during the second half of the twentieth century. The main cause has been determined to be higher levels of aerosols in the atmosphere and increased cloud cover, both of which reflect solar energy back to space, cooling the planet. Scientists believe that the cooling effect of aerosols has masked the real warming potential of greenhouse gases in the atmosphere and kept global temperature increases below what would otherwise have been the case. These findings mean that projections of future global temperature change could underestimate the real warming impact of anthropogenic greenhouse gas emissions.
