claim: Each unit of CO2 you put into the atmosphere has less and less of a warming impact.
evidence: The international community began the long process towards building effective international and domestic measures to tackle GHG emissions ( carbon dioxide, methane, nitrous oxide, hydroflurocarbons, perfluorocarbons, sulphur hexafluoride ) in response to the increasing assertions that global warming is happening due to man-made emissions and the uncertainty over its likely consequences.