Destruction of coastal habitats may release as much as 1 billion tons of carbon into the atmosphere each year, 10 times higher than previously reported, according to a new Duke led study.
Published online this week in PLOS ONE, the analysis provides the most comprehensive estimate of global carbon emissions from the loss of these coastal habitats to date: 0.15 to 1.2 billion tons. It suggests there is a high value associated with keeping these coastal-marine ecosystems intact as the release of their stored carbon costs roughly $6-$42 billion annually.
“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’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.”
This carbon, captured through biological processes and 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.
“There’s so little data out there on how much carbon might be released when these ecosystems are disturbed,” said Oregon State University’s Daniel Donato, co-lead author of the paper. “With this analysis we tried to reduce some of that uncertainty by identifying some ‘bookends’ that represent the lowest and highest probable emissions, given the information available.”