A further example of why chopping down mangrove forests, and destroying coastal salt marshes and sea grass beds is a bad idea: New research in PLoS ONE shows that we've radically underestimated the amount of greenhouse gases emitted every year from the destruction of coastal habitats.
In fact destruction of these ecosystems is contributing up to 1.2 billion tons of carbon into the atmosphere each year, 10 times more than previous estimates have shown.
Now, getting to the 'may' part of the headline...
The 1.2 billion tons figure is at the high end determined by the study—a figure the researchers point out is equal to that of the annual emissions of Japan. At the low end, however, 0.15 billion tons may be released.
The scientists say that there just isn't that much data available on these ecosystems and their current work attempted to provide "bookends that represent the lowest and highest probable emissions" from the destruction of these ecosystems, based on currently available information.
Study co-lead author Linwood Pendleton of the Nicholas Institute explains the type of landscape they researched, and the out-sized impact associated with their destruction:
These coastal ecosystems are a tiny ribbon of land, only 6% of the land area covered by tropical forest, but the emissions from their destruction are nearly one-fifth of those attributed to deforestation worldwide. One hectare of coastal marsh can contain the same amount of carbon as 488 cars produce in a year. Comparatively destroying one hectare of mangroves could produce as much greenhouse gas emissions as cutting down 3-5 hectares of tropical forest. (Science Daily)
As is the case with forests, these ecosystems absorb carbon from the atmosphere storing it both in the plants themselves and in the soil (or sea floor) in which they grow. Removing the vegetation or drying out the land, in the case of marshes, releases the stored carbon.