What is Blue Carbon?

“Blue carbon” refers to the vast amounts of carbon dioxide that Earth’s oceans absorb from the atmosphere. The name emerged in the 1990s when scientists realized the importance of marine vegetation as important carbon sinks. Along with forests, which store “green carbon,” coastal ecosystems such as mangrove swamps, salt marshes, peatlands, kelp beds, and sea grasses play a valuable role in the race to remove the greenhouse gases that cause climate change from the air. Yet like many of our land-based forests, we are losing these ecosystems to human encroachment, and when we do, these natural carbon sinks instead release enormous amounts of carbon, compounding our environmental challenges. Through photosynthesis, marine plants and algae extract carbon dioxide from the atmosphere throughout their growth cycle. When they die, the organic material precipitates to the ocean floor and gets embedded in soils, where it can remain undisturbed for millennia. More than two-thirds of the carbon on Earth circulates in the ocean, and oceans take up about 25% of the world’s annual Carbon Dioxide emissions. While coastal ecosystems constitute less than 2% of the total ocean area, they account for “approximately half of the total carbon sequestered in ocean sediments.” These environments store more carbon per area than land-based forests and at a rate three to five times faster, the equivalent of one billion barrels of oil per year. Wet soils retain more carbon because they have low oxygen levels, which slows down the rate of decomposition. That is also why the carbon trapped in coastal soils can remain there for thousands of years.