Summary of “global” factors that are well documented:
Intermittent “holes” in the ozone occur in nature.
The consistent decrease in stratospheric ozone was caused by people.
There is natural global warming and cooling.
Decreasing arctic ice (over the past 40 years) is significant and may directly result in major weather changes. 
The composition of the atmosphere is a factor in planetary temperature.
People are factor in composition of the atmosphere.  
The only responsible computation (to date to my knowledge) of the contribution
 people have made to climate change is 5% of the observed change.  
Bankers care about 5%, we should too.
                  Elwynn