The oxidizing capacity of the earth's atmosphere - Probable past and future changes

A number of critical atmospheric chemical problems depend on the earth's oxidizing capacity, which is essentially the global burden of oxidants in the lower atmosphere. There is limited direct evidence for changes in the earth's oxidizing capacity since recent preindustrial times when, because of industrial and poulation growth, increasing amounts of O3 precursor trace gases (carbon monoxide, nitrogen oxides, and hydrocarbons) have been released into the atmosphere. The concentrations of O3 and possibly H2O2 have increased over large regions. Models predict that tropospheric O3 will increase about 0.3-1.0 percent per year over the next 50 years with both positive and negative trends possible for OH and H2O2. Models and the observational network for oxidants are improving, but validation of global models is still at an early stage.