Brown Carbon From China

Modeling the climate we already have and the climate we might be getting is an important task that depends crucially on the atmospheric factors researchers take into account, especially if they relate to materials that contribute to greenhouse warming by absorbing light. Usually these carbonaceous particles are understood to be minimally-absorbing organic carbon (arising from processes in nature) and light-absorbing black carbon coming from the burning of fossil fuels, usually during the generation of electricity or biomass combustion. The size, amount, and optical properties of this carbon are regularly incorporated into computer simulations of climate studies.

Scientists have now studied another type of carbon aerosol, one with a brown color. This species of carbon consists of spheres much larger (up to ten times larger) than ordinary soot and, the researchers believe, are formed not during the original act of combustion but in some later condensation of carbon in the sky. The new study looked at air samples over the Yellow Sea, next to China. Peter Crozier and his colleagues argue that because these larger carbon spheres are rather abundant they need to be taken into account in future atmospheric warming models.

(The results were published in the 8 August issue of Science magazine.)