Current rates of mangrove loss are roughly estimated at around 150,000 hectares (370,050 acres) per year, or about 1% per annum (according to the United Nations Food and Agriculture Organization – FAO).
Mangrove loss = Loss of carbon sequestration potential
Almost 225,000 metric tons of carbon sequestration potential are lost each year with current rates of mangrove destruction.
Mangroves take up (sequester) approximately:
- 1.5 metric tons/hectare/yr of carbon
- 3.7 lbs/acre/day of carbon (1336 lbs/acre/yr)
Disturbed mangrove soils release greater than an additional 11 million metric tons of carbon annually.
Oxidation and release of stored mangrove carbon
Layers of soil and peat which make up the mangrove substrate have a high carbon content of 10% or more. Each hectare of mangrove sediment might contain nearly 700 metric tons of carbon per meter depth. When disturbed, carbon is released back into the atmosphere, further contributing to increased carbon emissions.
In building large numbers of shrimp farms, ranging in area from 1/2 hectare to several hectares in size, approximately 2 meters of sediment are dug out.
Clearing of mangroves and subsequent excavation of the mangrove substrate for shrimp ponds could result in the potential oxidation of 1,400 tons of carbon per ha.
According to Dr. Jin Eong Ong of the Universiti Sams in Malaysia, “Assuming that only half of this will become oxidized over a period of 10 years, we are looking at the return of 70 tons of carbon per hectare per year for ten years to the atmosphere.
“This is some 50 times the sequestration rate. This means that by converting a mere 2% of mangroves to shrimp aquaculture ponds, all of the advantages of mangroves as a sink of atmospheric carbon will be lost…”
Read Ong article (pdf 19 KB)
Restore mangroves – Sequester Carbon
MAP is working with organizations and communities in the global South and developed North toward conserving and restoringdegraded and destroyed mangrove areas.
Learn how to support MAP’s restoration efforts.