Blue Carbon …new name, old problem
Written by Caroline Silsbury
Thursday, 04 March 2010
World Wetlands Day has come and gone, but the event’s sponsor, the United Nations Environment Program, is still working to encourage better care for the world’s seacoasts. Last week, UNEP’s Executive Director and Indonesia’s Minister of Marine Affairs and Fisheries announced a joint “global scientific assessment on Blue Carbon”.
Blue carbon is the latest addition to UNEP’s climate change rainbow. “Black” and “brown” carbons are the soot and greenhouse gases produced when fossil fuels are burnt or carbon-containing materials (like garbage dumps and manure piles) break down. “Green” carbon refers to the greenhouse gases trapped and stored by the world’s forests and grasslands. “Blue” carbon refers to the portion trapped and stored in marine environments, including open sea, coral reefs, seagrass beds and coastal mangroves, estuaries and salt marshes.
The idea was actually launched with a report issued last October during National Marine Month in South Africa. The name “blue carbon” came from the report’s estimate that about 55% of the carbon dioxide captured and stored by the world’s natural carbon “sinks” went into marine environments. Plants – seagrass, mangroves and marshes – account for only about 1% of the total marine area but do about 70% of the carbon capturing.
We have known for a long time about the value of these areas as water purifiers, coastal defenses and nurseries for birds and marine life. They are vital to food security for nearly half the world’s people, including many of the poorest. In fact, the UNEP report puts an average annual “service value” of about US$90,000 on each hectare of the world’s mangroves, and about US$12,000 per hectare on seagrass beds. (A hectare is about 2.5 acres.)
Their value as intense, hard-working carbon sinks has been less appreciated. The total mass of marine plant life is tiny compared to the mass on land, but the UNEP report estimates that it traps just as much carbon dioxide every year. And marine carbon sinks are almost permanent. Carbon that finds its way to the sea floor will stay there for thousands of years, compared to a few decades for rainforests.
However, these areas are being damaged or destroyed, mostly by bad land use management. According to the report’s editor, “Since the 1940’s, over 30% of the mangroves, close to 25% of salt marshes and over 30% of seagrass meadows have been lost. We are losing these crucial ecosystems much faster than rainforests and at the very time we need them.”
The remedy, it seems, is “Save what’s left. Then plant more.” In fact, there has been a lot of mangrove replanting in Southeast Asia, especially in Vietnam and Indonesia. Salt marshes are being restored in the U.S. and Europe. In the Caribbrean, though, we’re just getting to “Save what’s left”.
UNEP has proposed a Blue Carbon Fund to provide technical and financial support for improved coastal management. This will likely be similar to the program that now pays developing countries to stop deforestation on land, and helps them sell the resulting “green carbon” credits. There may also be a profit opportunity in saving seagrass, mangroves and marshes. One of new fund’s objectives will be to measure and define blue carbon areas, and help the countries that look after them to market carbon credits – doing well by doing good.
