NASA Earth Observatory. download large image (4 MB, PDF). Methane is an important trace gas in Earth’s atmosphere. Even though it only makes up 0.00017% (1.7 parts per million by volume) of the the atmosphere, methane traps a significant amount of heat, helping the planet remain warm and habitable.ASA Earth Observatory. download large image (4 MB, PDF). Methane is an important trace gas in Earth’s atmosphere. Even though it only makes up 0.00017% (1.7 parts per million by volume) of the the atmosphere, methane traps a significant amount of heat, helping the planet remain warm and habitable.