Climatic impact of carbonaceous aerosols Although much more
difficult to assess than that of greenhouse gases, the climatic
role of aerosols is now an established fact. What is more, it is
the subject of a number of debates since a recent American study
(Hansen et al., 2000) showed that, in order to reduce climate
warming, the effort should concern carbonaceous aerosols as well
as greenhouse gas emissions. The study of the radiative impact
of carbonaceous aerosols is only beginning. This impact is
complex and multiple, due to the heterogeneity of the
geographical distribution of aerosols and to their
characteristics. Carbonaceous aerosols are composed of two
fractions of variable proportions with antagonistic radiative
properties: organic carbon (OC), whose direct radiative effect
mainly produces a cooling of the atmosphere, and black carbon
(BC), which has a warming effect. Strategies involving the
reduction of combustion-related CO2 emissions have a deep impact
on the production of carbonaceous particles, s