Traces of methane gas (about 0.0002% or 1745 ppb) occur in the Earth's atmosphere, produced primarily by methanogenic microorganisms, such as Archaea in the gut of ruminants.
tɹˈeɪsᵻz ʌv mˈɛθeɪn ɡˈæs ɐbˌaʊt zˈiəɹoʊ.zˈiəɹoʊzˈiəɹoʊzˈiəɹoʊtˈuː pɚsˈɛnt ɔːɹ wˈʌn θˈaʊzənd sˈɛvənhˈʌndɹɪd fˈoːɹɾi fˈaɪv pˌiːpˌiːbˈiː əkˈɜːɹ ɪnðɪ ˈɜːθz ˈætməsfˌɪɹ, pɹədˈuːst pɹaɪmˈɛɹᵻli baɪ mˌɛθɐnoʊdʒˈɛnɪk mˌaɪkɹoʊˈɔːɹɡənˌɪzəmz, sˈʌtʃ ɐz ɑːɹkˈiə ɪnðə ɡˈʌt ʌv ɹˈuːmɪnənts.