Measurement accuracy offsets between laboratories and scale contraction effects are technical pitfalls in the isotopic analysis of atmospheric CH4 that could be prevented if a suite of international isotope reference gases was available to all laboratories.Unfortunately,such reference material does not exist for CH4 in air.We are developing two methods to incorporate the hydrogen of VSMOW and the carbon of VPDB isotope scale material into CH4,so the CH4 is then itself representing the VSMOW and VPDB isotope reference scales for δ2H-CH4 and δ13C-CH4,respectively.