Carbon Dioxide

I need some substantial discussion and information to help men understand and answer the following questions in a summary format. Also, I'm looking for good comprehensive examples that will add content to the answers.
What is the greenhouse effect, and how does it work?
What are the main greenhouse gases?
What is the present level of atmospheric carbon dioxide? Why has carbon dioxide concentration risen since 1860?
What are some predicted environmental damages if carbon dioxide emissions are not reduced?
In your analysis, how certain do we need to be about future predictions before acting on this problem?