the earth 's atmosphere is made of 04 to 1 percent water vapor by volume & water vapor is a kind of greenhouse gas ->  water vapor is a greenhouse gas accounting for 04 to 1 percent of the earth's atmosphere  carbon dioxide is a kind of greenhouse gas & the earth 's atmosphere is made of 036 percent carbon dioxide by volume ->  carbon dioxide is a greehouse gas accounting for 0036 percent of the earth's atmosphere  water vapor is a greenhouse gas accounting for 04 to 1 percent of the earth's atmosphere & carbon dioxide is a greehouse gas accounting for 0036 percent of the earth's atmosphere & 04 is bigger than 0036 -> water vapor is the largest amount of greenhouse gas in the atmosphere