Marine anoxic carbon storage projects are a carbon-removal project type within the ocean & water segment of the carbon market. They involve biomass deposited in deep anoxic marine basins intended to slow decomposition and isolate carbon. In practice, biomass carbon is isolated from decomposition in an approved storage environment. Common project configurations include Depositing sustainably sourced lignin-rich biomass in anoxic marine basins under methodology controls.

The concept is still early and subject to significant scientific and governance scrutiny, which is why standards and safeguards are especially important. Ocean-based pathways are developing quickly and can be scientifically compelling, but they generally require especially careful MRV, strong ecological safeguards, and a clear accounting framework for permanence and reversals. For buyers and program designers, the most important diligence questions are: Are ecological safeguards, biomass sourcing, permanence assumptions, and marine governance robust enough for scaling?