Atmospheric nitrous-oxide (N2O) is currently the most significant agent of stratospheric ozone depletion and also an important greenhouse gas. Oceanic emissions provide approximately a third of the natural sources of N2O to the atmosphere. N2O is produced in the ocean during the remineralisation of organic matter, by a combination of microbially-mediated processes that also display significant sensitivity to local oxygen level. Questions remain on the magnitude and distribution of the oceanic N2O flux to the atmosphere, on the underlying cycling mechanisms, and on how oceanic emissions will evolve under the impacts of global change (e.g., ocean warming, deoxygenation, and anthropogenic impacts on the marine nitrogen cycle).
In this talk I will present recent estimates of oceanic N2O emissions derived from global ocean biogeochemistry models in combination with observational datasets. I will discuss current model challenges towards obtaining accurate flux estimates, and also report on an ongoing ocean N2O model inter-comparison in support of the Global Carbon Project’s N2O budget initiative.