Destroyed coastal habitats may release tonnes of carbon

September 7th, 2012 - 2:25 pm ICT by IANS  

Washington, Sep 7 (IANS) Destruction of coastal habitats may saddle the atmosphere with an additional billion tonnes of carbon every year, 10 times higher than previously reported, according to a new study.

This carbon, stored in the sediment below mangroves, sea grasses and salt marshes, is called “blue carbon”.

When these wetlands are drained and destroyed, the sediment layers below begin to oxidize. Once this soil, which can be many feet deep, is exposed to air or ocean water it releases carbon dioxide over days or years.

The analysis provides the most comprehensive estimate of global carbon emissions from the loss of these coastal habitats to date. It suggests the release of their stored carbon costs roughly $6-$42 billion annually, the journal Public Library of Science ONE reported.

“On the high end of our estimates, emissions are almost as much as the carbon dioxide emissions produced by the world’s fifth-largest emitter, Japan,” said Brian Murray, director for economic analysis at Duke University’s Nicholas Institute for Environmental Policy Solutions.

“This means we have previously ignored a source of greenhouse gas emissions that could rival the emissions of many developed nations,” added Murray, according to a university statement.

“There’s so little data out there on how much carbon might be released when these eco-systems are disturbed,” said Oregon State University’s Daniel Donato, who led the study with Murray.

“These coastal eco-systems are a tiny ribbon of land, only six percent of the land area covered by tropical forest, but the emissions from their destruction are nearly one-fifth of those attributed to deforestation worldwide,” said Linwood Pendleton, study co-author and director of the Ocean and Coastal Policy Program at the Nicholas Institute.

“One hectare, or roughly two acres of coastal marsh, can contain the same amount of carbon as 488 cars produce in a year. Comparatively, destroying a hectare of mangroves could produce as much greenhouse gas emissions as cutting down three to five hectares of tropical forest,” added Pendleton.

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