Coastal wetlands vegetated by common reed and rice paddies emit significant amounts of methane to the atmosphere whereas sea-blite marshes are net sinks for atmospheric methane. The main controlling factors for the methane emissions are water table, temperature, soil organic carbon and salinity. The methane emissions from coastal wetlands can be reduced by creating fluctuating water tables, including water tables below the soil surface, as well as by occasional flooding by high-salinity water.