A mangrove nitrous oxide sink attenuates methane climate impacts

Abstract We resolve mangrove nitrous oxide (N 2 O), methane (CH 4 ), and carbon dioxide (CO 2 ) vertical exchange with the atmosphere and lateral exchange with the ocean. Our new observations in Brazil were combined with literature data to reassess the overall mangrove carbon sequestration potential. The pristine mangrove creek was a source of CO 2 and CH 4 , and a sink for N 2 O. The CO 2 ‐equivalent N 2 O uptake offset up to 71% of local CH 4 emissions. Global mangrove N 2 O sinks offset 34% of water–air CH 4 emissions, potentially absorbing 0.6 Tg CO 2 equivalents per year. Overlooking lateral exchange led to a large underestimation of mangrove N 2 O and CH 4 fluxes. Previous observations in mangroves receiving nitrogen‐rich freshwater may have misattributed N 2 O sources. Pristine seawater‐dominated mangroves typically act as N 2 O sinks while those influenced by anthropogenic inputs are sources. Overall, the observed N 2 O sink further enhances the net climate benefit of mangroves.