CLIMATE EFFECTS OF SULPHATE AND BLACK CARBON ESTIMATED IN A GLOBAL CLIMATE MODEL

摘要

The work on climatic effects of aerosols has not come far enough to draw any firm conclusions, mainly due to uncertainties w.r.t. indirect effects. The concentration calculations as well as the forcing estimates need validation. Also organic carbon (OC), a large group of primary and secondary organic particles, should be included. Penner et al.(1996) estimated much larger indirect effects of OC to than the of sulphate, because OC-particles are not produced in clouds as opposed to sulphate. On the other hand, the indirect effects of sulphate estimated by Lohmann and Feichter (1997) is probably too high, since they did not take into account that much sulphate is produced in pre-existing droplets. The anthropogenic OC-burden in the troposphere is poorly known. Table 2 summarises our forcing estimates along with results by others. Despite the uncertainties it appears quite certain that the aerosols' impacts on radiative forcing is comparable to greenhouse gases. The pronounced regional patterns may affect the climate system more efficiently than indicated by the net global forcing. Climate scenario simulations are needed to reveal this.