In a recent highly publicised paper, Keppler et al. [1] report the remarkable observation that methane is emitted directly by plants, and in an aerobic environment. Previously, emissions from vegetation were attributed to anaerobic microbial associations (e.g. in water-logged soils). But how important is this new source of what is a potent greenhouse gas? Keppler et al. [1] make a calculation that would estimate plant emissions to comprise 11–46% [2] of the current total annual methane emissions.