The various issues arising fro the pollution of Earth's atmosphere by a number of substances are often closely interrelate, both through chemistry and through potential control strategies. For example, chlorofluorocarbons (CFCs) both destroy ozone and are greenhouse gases; conservation of fossil fuels would contribute to addressing both acid rain and climate change problems; ozone depletion in the lower stratosphere and increasing aerosol concentrations have a cooling effect, which may be partially offsetting, and hence masking, the full extent of the enhanced greenhouse effect.
Sooner or later, the worst possible set of circumstances is bound to occur.
By definition, when you are investigating the unknown you do not know what you will find.