Prof. Wofsy’s work focuses on measuring, modeling, and mitigating the vast impacts that human beings have on the atmosphere. Combustion of fossil fuel, clearing of forests, agriculture, and chemical industry have caused concentrations of the most important atmospheric trace gases (CO2, CH4, N2O) to increase over the past 200 years, with accelerating change in the last 50 years. Emissions of industrial halocarbons (CFCs, such as CF2Cl2, "CFC-12") caused stratospheric ozone declines and formation of the Antarctic ozone “hole”. These changes have serious impacts on the environment of the earth and on society, such as climatic warming and global, regional and urban air pollution. Professor Wofsy’s research over many years has been motivated by the need for scientific information and analysis to make wise decisions on the future development and conservation of the world's resources.