The chemistry of stratospheric ozone

Compelling observational evidence shows that the chemical composition of the atmosphere is changing on a global scale at a rapid rate. The atmospheric concentrations of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and chloroflourocarbons (CFCs) 11 (CFCl3) and 12 (CF2Cl2) are currently increasing at rate ranging from 0.2 to 5% per year. The concentrations of other cases, including CFC 113 (C2F3Cl3) and halons 121 (CF2ClBr) and 1301 (CF3Br), important in the ozone depletion and global warming issues, are also increasing (at even faster rates). These changes in atmospheric composition reflect, on one part, the metabolism of the biosphere and, on another, the broad range of influencing human activities, including industrial, agricultural, and combustion practices. The only known sources of the CFCs and halons are industrial production prior to their use as aerosol propellants, refrigerants, foam blowing agents, solvents, and fire retardants. One of our greatest difficulties in accurately predicting future changes in ozone or global warming is our inability to predict the future atmospheric concentrations of these gases. This paper discusses the role of the biosphere in regulating the emissions of gases such as CH4, CO2, N2O, and methyl chloride (CH3Cl) to the atmosphere as well as the most probable future industrial release rates of the CFCs, halons, N2O, carbon monoxide (CO), and CO2, which depend upon a variety of economic, social, and political factors