The Carbon Culprits

Carbon dioxide gets the most attention because of its volume — humans release over forty billion tons annually, primarily from burning fossil fuels. But CO2 is not the most potent greenhouse gas per molecule.

Methane traps roughly eighty times more heat than CO2 over a twenty-year period.

Water vapor is actually the most abundant greenhouse gas, but humans do not emit it directly in significant quantities. Instead, as CO2 and methane warm the atmosphere, more water evaporates from oceans, which traps more heat, which causes more evaporation.