Quote from Ricter:
Yes, we do. Just like adding a layer of glass to a greenhouse raises the greenhouse's interior temperature. What we don't know for sure is the sum of all the effects of other variables inside the greenhouse, but all other things being equal...
But don't take my word for it, look again at the statement on the matter from science.nasa.gov.
show us the proof that adding co2 to our environment causes warming.
all the info and data out right now says that climate sensitivity is far less than what the ipcc has been claiming which is why their models failed. The recent research done by some shows that the climates response to forcings is non linear.
At first adding greenhouse gases may cause warming but as you add more their effect non only ceases warming but aerosols and water vapor begin to cause cooling. (as they are finding now.)
We also know that co2 causes cooling in the upper atmosphere so what happens when you add more and it migrates up? cooling.