Global inventory of doubly substituted isotopologues of methane (Δ13CH3D and Δ12CH2D2)
Measurements of methane (CH4) molecules containing two rare isotopes (13CH3D and 12CH2D2), also termed doubly substituted or "clumped" isotopologues, have the potential to provide two additional isotopic dimensions to help investigate the mechanisms underlying global atmospheric trends in CH4. In this work, we summarise the current state of research on doubly substituted CH4 isotopologues, with an
