This doctoral thesis in history, sociology and philosophy of science intends to investigate the alterations of atmospheric chemistry as a scientific field and as an expertise field, from the mid-1980s. Some primary investigations have implied that these alterations may have been brought about by the rise of a climate change issue, as well as by new emerging ways of making atmospheric and environmental sciences. Moreover, the coming back of geoengineering as a political stake (after e.g. its use by the U.S. as weather warfare in the forests over North and South Vietnam, Laos, and Cambodia between 1967 and 1972) could constitute a new stage of evolution for atmospheric sciences. 

After a first introductive part on the building up of an atmospheric chemists' community around critical issues such as urban pollution, acid rains and ozone-layer depletion, the second and central part of our work will question how climate change has altered the epistemological and political ways atmospheric chemists have been producing and promoting their knowledge for the past thirty years. The last part deals with the geoengineering projects linked to atmospheric chemistry.