Seasonal wetting and drying dynamics drive greenhouse gas emissions across Australia’s river network

Streams and rivers are major contributors to global emissions of carbon dioxide and methane, yet seasonal hydrological variability in discharge and river surface area is often not fully represented in large-scale emission estimates. Here, we integrate riverine and dry riverbed carbon dioxide and methane data with geospatial data of the Australian drainage network to predict emissions at a monthly time-step. We show that flowing Australian rivers emit a total of 48.5 teragrams of carbon dioxide and 0.28 teragrams of methane annually, with dry riverbeds adding 13.9 teragrams of carbon dioxide, according to integrated river emission measurements and geospatial drainage network analysis. Spatiotemporal emission patterns closely follow variations in river surface area, with contrasting seasonal pulses from tropical regions in the wet season and temperate regions in winter. These results highlight the importance of hydrological dynamics, particularly the seasonal expansion and contraction of river networks, in governing riverine emissions across Australia. Australian rivers emit 48.5 teragrams of carbon dioxide and 0.28 teragrams of methane annually, with dry riverbeds adding 13.9 teragrams of carbon dioxide, according to integrated river emission measurements and geospatial drainage network analysis.