Train-borne measurements of tropical methane enhancements from ephemeral wetlands in Australia

We report greenhouse gas concentrations measured on a train covering a north-south transect through central Australia from north to south coast. During the monsoonal wet season we found significant enhancements in methane that correlate well with changing area of wetland inundation in Australian tropical savanna regions. We used a meteorological and air pollution model to quantify the ephemeral wetland fluxes necessary to cause the observed enhancements and estimate the constant Australian tropical wetland emissions. Annual Australian tropical ephemeral wetland fluxes are estimated at 0.4 +/- 0.2 Tg CH4, with permanent wetlands contributing a similar amount, 0.5 +/- 0.2 Tg CH4.