claim: Greenhouse gases have been the main contributor of warming since 1970.
evidence: The seven sources of CO 2 from fossil fuel combustion are ( with percentage contributions for 2000–2004 ) : Carbon dioxide, methane, nitrous oxide ( N 2O ) and three groups of fluorinated gases ( sulfur hexafluoride ( SF 6 ), hydrofluorocarbons ( HFCs ), and perfluorocarbons ( PFCs ) ) are the major anthropogenic greenhouse gases, and are regulated under the Kyoto Protocol international treaty, which came into force in 2005.