Tropicalization Enhances Mangrove Methane Emissions to the Atmosphere

Abstract Organic‐rich mangrove soils release CH 4 , partially offsetting the climate benefits of high organic carbon sequestration. However, the local and global drivers and variability of mangrove CH 4 emissions remain poorly understood. Here, we quantify water‐atmosphere CH 4 emissions over hourly, daily, and weekly time scales in an Australian mangrove ecosystem. We then combine our new observations with earlier data sets to link temperature and mangrove CH 4 emissions on the global scale. The water‐atmosphere CH 4 emissions were partially controlled by temperature on both local and global scales. One degree warming increased mangrove water‐atmosphere CH 4 emissions by ∼23% locally and ∼13% globally. Globally scaled water‐atmosphere CH 4 emissions (0.07–0.10 Tg C yr −1 ) currently offset 6%–8% of mangrove carbon burial. CH 4 emissions are predicted to increase by 10%–33% by 2100 under global warming scenarios and tropicalization. Therefore, mangrove CH 4 emissions should be considered in blue carbon assessments in the context of global warming.