So all current worries are based on predictions of the response of the atmosphere to expected increases in emissions of greenhouse gases. The Second World Climatic Conference brought a high level of consensus among scientists that warming was probable and would be best avoided, but responses from politicians were muted. First, the causes of increased emissions include the key activities which sustain life and promise affluence. Second, an effective response must be global and is prevented by sharp differences in the interests of different countries. Methane is produced by rice paddies and cattle, as well as leaks from gas pipelines.
Nitrous oxide comes from vehicles, deforestation and agriculture.
Only CFCs are relatively easy to control, but they are extremely persistent once emitted. Apart from CFCs, controlling emissions of greenhouse gases would require huge increases in energy efficiency and the transformation of agriculture as well as reversal of deforestation. Agreement to implement such huge changes would have to overcome differences between countries. The more developed countries use much more energy than the less-developed, so they are arguably responsible for the problem. But they are reluctant to reduce coal or oil burning appreciably.