Working Group 1: Measurements
WG1 is responsible for producing the observational data needed to constrain the sources and sinks of atmospheric methane (CH4) and its isotopologues. This group leads both continuous monitoring efforts and targeted measurement campaigns, using advanced laboratory and field techniques to generate globally distributed and historically significant datasets.
Although methane is the second most important anthropogenic greenhouse gas, major uncertainties remain in its atmospheric budget. The lack of comprehensive data on source types (fossil, microbial, biomass burning) and chemical sinks (primarily oxidation by OH) limits our ability to understand both current trends and long-term climate feedbacks. Isotopic measurements of methane and its co-emitted species offer key insights, but until recently, these measurements were rare and lacked global coverage.
WG1 recently completed a full year of 14CO sampling at a global network of clean-air sites. These same sites are now being used to collect 14CH4 samples, with semi-automated sampling systems deployed in locations such as Alaska, the Canary Islands, Barbados, New Zealand, and American Sãmoa. We have collected more than 500 measurements of δD and δ13C of CH4 at nine stations worldwide. INSTAAR has completed development of a high-precision δD-CH4 system, and is now preparing to analyze NOAA flask samples. Lab-based studies of the kinetic isotope effect (KIE) in CH4+OH reactions are also underway. In addition, WG1 has launched the first intercomparison of 14CH4 measurements among five international laboratories.
WG1 will continue expanding its global measurement campaign, complete key laboratory experiments, and begin analyzing air samples from Greenland once recovered. These data will serve as anchor points for both the model simulations and machine learning efforts, helping to close the methane budget over time.