Kelp and other types of seaweed are not merely staples in the Japanese diet. There are growing expectations that they can play a role in mitigating climate change, with the government promoting the usage of so-called ‘blue carbon’ that’s stored in coastal and marine ecosystems.

Blue carbon is a sister of sorts to ‘green carbon,’ which refers to carbon stored in terrestrial ecosystems (i.e., forests, peatlands, and grasslands). Blue carbon began to gain attention following a 2009 report by the United Nations Environment Program (UNEP) that defined it as a new option for carbon sink measures to remove CO2 from the atmosphere.

The ocean is among the world’s largest carbon sinks, along with soil and forests. Coastal habitats like seagrass lands, mangroves, and salt marshes cover less than2% of total ocean area, but they account for about half of all sequestered CO2 in ocean sediments, according to the Blue Carbon Initiative (BCI), which brings together governments, research institutions and NGOs.

Coastal blue carbon ecosystems, however, are also among the most endangered, according to BCI, which estimates that 340,000 to 980,000 hectares are destroyed every year. Up to 67%, and at least 35% and 29% of the global coverage of mangroves, tidal marshes, and seagrass meadows, respectively, may have been lost so far. Furthermore, when degraded or lost, these ecosystems can release significant amounts of CO2 that’s been stored for centuries.

A new inter-ministerial initiative in Japan is starting to tackle the issue by addressing a blue carbon area that’s received little attention to date.