To accurately assess the current atmospheric methane budget and its future trends, it is essential to apportion and quantify the anthropogenic methane emissions to specific sources. This poses a significant challenge in the under-sampled Middle East, where estimates predominantly depend on remote sensing observations and bottom-up reporting of national emissions.

Here, we present in situ shipborne observations of greenhouse gases (GHGs) and non-methane hydrocarbons (NMHCs) collected along a >10,000-km route from Vigo, Spain, to Abu Dhabi, UAE. By comparing our observations with Lagrangian dispersion model simulations, coupled with two methane emission inventories, we identify periods of considerable mismatch and apportion the responsible sources.

Employing interspecies relationships with NMHCs has enabled the characterization of methane emissions from oil and gas (O&G) operations, urban centers, Red Sea deep water, enteric fermentation, and agriculture across diverse atmospheric environments.