Blue carbon is defined by the IPCC as: "Biologically driven carbon fluxes and storage in marine systems that are amenable to management."
Another definition states: "Blue carbon refers to organic carbon that is captured and stored by the oceans and coastal ecosystems, particularly by vegetated coastal ecosystems: seagrass meadows, tidal marshes, and mangrove forests."
Coastal blue carbon focuses on "rooted vegetation in the coastal zone, such as tidal marshes, mangroves and seagrasses". Seagrass, salt marshes and mangroves are sometimes referred to as "blue forests" in contrast to land-based "green forests".
Deep blue carbon is located in the high seas beyond national jurisdictions. It includes carbon contained in "continental shelf waters, deep-sea waters and the sea floor beneath them" and makes up 90% of all ocean carbon. Deep blue carbon is generally seen as "less amenable to management" and challenging due to lack of data "relating to the permanence of their carbon stores".