Aerosol forcing, climate response and climate sensitivity in the Hadley Centre climate model

An atmosphere/mixed-layer-ocean climate model is used to investigate the climate responses to forcing by 1860-2000 changes in anthropogenic sulfate, biomass-burning and black carbon aerosols, and how they compare with the effect of doubling CO2. While the patterns of temperature response from sulfate and black carbon aerosols are similar and reveal high sensitivity at high latitudes in the northern hemisphere, they are significantly different to that due to CO2 which shows high latitude sensitivity in both hemispheres, and to biomass-burning aerosols which shows a much more uniform temperature response. Climate sensitivity, the response of natural primary aerosols, and the degree to which forcings and responses are additive, are also investigated. The sum of the separate temperature and precipitation responses to each aerosol is found to be remarkably similar to that obtained if all aerosols are changed simultaneously.