Found along the edges of much of the world’s tropical coastlines, mangroves are absorbing carbon dioxide from the
atmosphere at an impressive rate. Protecting them, a recent study says, could yield climate benefits, biodiversity
conservation and protection for local economies for a nominal cost — between $4 and $10 per ton of CO2.
Mangrove forests are ecosystems that lie at the confluence of freshwater rivers and salty seas. While they make up only 0.7
percent of the world’s forests, they have the potential to store about 2.5 times as much CO2 as humans produce globally
each year.
These environments, along with other forms of coastal ecosystems such as tidal marshes and sea grasses, have been given the
name “blue carbon” to differentiate them from the “green” carbon of other forests, where carbon is absorbed above ground in
trees.
Shrimp aquaculture, fishing and rice growing — especially in Southeast Asia — are slowly degrading mangroves. Every five
to 20 years, a biological or chemical problem affects a pond, forcing farmers or fishermen to abandon the area and dig a
new pond in an undisturbed mangrove forest. A World Bank study last year found that the removal of the typical coastal
wetland has added about 2,000 metric tons of carbon dioxide per square kilometer per year to the atmosphere over 50 years
In forests, researchers can use remote sensing data like satellite images and possibly verify those data with information
on the ground. For soils, scientists must measure the carbon content of a particular soil at a specific location and
develop a map from that.
The science of soil carbon dynamics is evolving, with some researchers finding that soil could even play a role in boosting
greenhouse gas emissions
http://www.scientificamerican.com/article.cfm?id=restoring-mangroves-may-prove-cheap-way-to-cool-climate