A similar process has already enabled some control over the global levels of ozone-destroying chlorofluorocarbons. Control of other gases, especially carbon dioxide, is also theoretically possible but could be much more difficult. The perturbation of the carbon cycle by anthropogenic emissions has been in progress since before the time of Arrhenius, and will take some time to restore. And because of the dependence of modern economies on fossil-fuels, reducing emissions will require major policy changes. In conclusion, we know that the composition of global atmosphere is changing.
Human activities are a major cause.
Management of our atmosphere s composition may be possible. The scientific understanding of the causes is improving but not complete. Then we may have more ability to predict or even manage future changes. We must also keep in mind that the atmosphere is a complex system and there may be surprises in store. Respiration of plants and trees is more important.