Aerosols and Climate

Prof. John H. Seinfeld
Division of Chemistry and Chemical Engineering
California Institute of Technology
Pasadena, CA  

Lavoisier Lecture #1
Department of Chemistry
University Paris Diderot – Paris 7

November 23, 2011
10:30 am

Atmospheric  particles  generally  exert  a  cooling  effect  on  climate  that counteracts  warming  from  greenhouse  gases.  The  amount  of  radiative  forcing  due  to  aerosols  is  generally  considered  as  the  most  uncertain component of the overall radiative forcing from pre-industrial to present day.
Aerosols scatter and absorb incoming solar radiation (referred to the direct effect)  and  act  as  cloud  condensation  nuclei  (referred  to  as  the  indirect effect).  While  most  aerosol  inorganic  and  organic  constituents  are  purely scattering  in  nature,  black  carbon  absorbs  solar  radiation  and  heats  the atmosphere.  The  overall  optical  properties  of  the  aerosol  depend  on  the fraction  of  black  carbon.  The  effect  of  aerosol  perturbations  on  cloud properties is considered as the most uncertain of the aerosol effects. In this presentation, we will review the current understanding of aerosol effects on climate  and  the  prospects  for  improving  estimates  of  aerosol  forcing  of climate.

Amphithéâtre Buffon, Rez-de-chaussée bas  
15 rue Hélène Brion, 75013 Paris