The Global Warming Potential of a Gas refers to the total contribution to global warming resulting from the emission of one unit of that gas relative to one unit of the reference gas, carbon dioxide, which is assigned a value of 1. For example, if methane has a global warming potential of 21, it means that 1 kg of methane has the same impact on climate change as 21 kg of carbon dioxide and thus 1 kg of methane would count as 21 kg of carbon dioxide equivalent. (Source: www.greenfacts.org/)
