claim: there is no relationship between temperature and carbon dioxide emissions by humans[...] carbon dioxide has had a minuscule effect on global climate
evidence: NARRATOR: Only in the last few decades do rising global temperatures seem to coincide with the greenhouse gases we put into the atmosphere. [...] CO2 is minuscule, but through an accident of physics - the greenhouse effect -its consequences are significant. [...] FRED SINGER, George Mason University: I have no doubt that an increase in carbon dioxide in the atmosphere should lead to some increase in global temperatures. The question is, how much? And how can we be sure that any temperature increase that we do find in the record is, in fact, due to this additional carbon dioxide? Since we know that the climate also changes naturally - it warms, it cools - how can you distinguish a warming produced by an increase in carbon dioxide from a warming produced by some other cause, let's say by the sun?