HFC-134a is short for hydrofluorocarbon. Like CO2, he belongs to the band of baddies. Mercifully, HFC-134a does not linger in the atmosphere for long — just a few years. But at eight atoms, he is much larger than his compatriot, and he absorbs far more infrared light. In the short term, HFC-134a has 3,790 times the heating power of CO2.