Global methane emission estimates from ultraviolet irradiation of terrestrial plant foliage

Several studies have reported in situ methane (CH₄) emissions from vegetation foliage, but there remains considerable debate about its significance as a global source. Here, we report a study that evaluates the role of ultraviolet (UV) radiation-driven CH₄ emissions from foliar pectin as a global CH₄ source. We combine a relationship for spectrally weighted CH₄ production from pectin with a global UV irradiation climatology model, satellite-derived leaf area index (LAI) and air temperature data to estimate the potential global CH₄ emissions from vegetation foliage. Our results suggest that global foliar CH₄ emissions from UV-irradiated pectin could account for 0.2-1.0 Tg yr^-1, of which 60% is from tropical latitudes, corresponding to < 0.2% of total CH₄ sources. Our estimate is one to two orders of magnitude lower than previous estimates of global foliar CH₄ emissions. Recent studies have reported that pectin is not the only molecular source of UV-driven CH₄ emissions and that other environmental stresses may also generate CH₄. Consequently, further evaluation of such mechanisms of CH₄ generation is needed to confirm the contribution of foliage to the global CH₄ budget. No claim to original US government works. Journal compilation