Freshwater aquaculture is a rapidly growing and important source of global blue foods, but produces substantial methane (CH₄) and nitrous oxide (N₂O) emissions from the aquatic environment. Meanwhile, marine aquaculture (mariculture) is a smaller sector with a large growth potential, but its climate impacts have not been accurately quantified due to observation scarcity. Here, based on marine biogeochemical cycles, we assess the greenhouse gas (GHG) emissions from mariculture’s aquatic environment in global potentially suitable areas at 10-km resolution, using GHG measurements from research cruises and satellite-observed net primary productivity. Mariculture’s aquatic emission intensities are estimated to be 1–6 gCH₄kg^-1CW (carcass weight) and 0.05–0.2 gN₂Okg^-1CW, >98% and >80% lower than freshwater systems because of suppressed microbial production in marine waters and inefficient ventilation to the atmosphere. The life-cycle assessment shows that mariculture’s carbon footprints are ~40% lower than those of freshwater aquaculture, suggesting considerable climate benefits of mariculture expansion to meet future protein needs.

marine aquaculture,greenhouse gas emissions,adaptation and mitigation measures