It’s probably fair to say that the importance of the greenhouse gas in the absorption of heat is proportional to the its area on the graph. The sum of all the blue areas equals water’s importance and the tiny green area is CO2’s importance. Doesn’t the blue area look more than ten times as large? Maybe as much as 30 times as large? That means water contributes between 1000% to 3000% more to the greenhouse effect than CO2. And the water is all natural.