Missing methane emissions from terrestrial plant leaves.

The striking apparent discovery that terrestrial plants aerobically emit CH4 remains to be corroborated with independent methodologies, and uncertainties associated with experimental procedures and analytical measurements cast doubt on current evidence. Here we show using simultaneous on-line measurements of CH4 fluxes and CO2 exchange that leaves of species with the C4 and C3 photosynthetic pathways are not statistically significant CH4 emitters. Our findings call into question those of Keppler et al. (2006), and suggest that attribution of anomalously high CH4 concentrations in the tropical troposphere to aerobic CH4 emissions by plants is premature