Mangrove conservation is 'economic' CO2 fix
Protecting mangroves to lock carbon away in trees may be an economic way to curb climate change, research suggests.
Carbon credit schemes already exist for rainforests; the new work suggests mangroves could be included too.
But other researchers say the economics depend on the global carbon price.
Presenting their results in Proceedings of the National Academy of Sciences (PNAS), the US-based team emphasises that protecting mangroves has important benefits for wildlife as well.
Mangrove habitats comprise less than 1% of all forest areas across the world.
But for the biodiversity they support, and the benefits they bring to communities in the form of fishing habitats and storm protection barriers, they are extremely important.
They are also being lost at a greater rate than tropical rainforests.
Similar to rainforests, they store carbon within their "biomass", which is released when the habitat is destroyed.
Their ability to capture carbon may be on average five times that of tropical rainforests, so they have become of interest to carbon-focused conservation strategists.
Now, Dr Juha Siikamaki of the think tank Resources for the Future and his US colleagues have shown that protecting mangroves and thereby reducing the amount of CO2 released may be an affordable way for countries to mitigate their carbon emissions.
"We make the surprising finding that in most places, preserving mangroves is justified solely based on the avoided emissions, without any regard for the many other ecological and economic benefits mangroves are particularly well known for," Dr Siikamaki told BBC News.
The research, which used new high resolution surveys of global mangrove biomass, suggests that protecting these habitats could be a viable means for reducing emissions in comparison to other "carbon offset" methods.
"The bonus is that in doing so, we can preserve important habitats critical to coastal fisheries, rich in biodiversity, and home to hundreds of species of plants and animals, many of them endangered," co-author Professor James Sanchirico, from the University of California, Davis, said in a press statement.
But Freya Roberts, a researcher at fact-checking service The Carbon Brief, told BBC News that the price of carbon quoted - on which this research is based - might be out-dated.
"Since [the research was conducted], carbon prices have dropped due to an over-supply of permits," she said.
"With too many permits available, and poor economic conditions meaning big businesses are emitting less carbon dioxide, competition isn't forcing the carbon price up."
Other incentive programs are available, such as the EU's Emission Trading Scheme (ETS). The authors report that the preservation of mangroves is cheaper than these other schemes; but Ms Roberts remained cautious.
"Carbon permits now cost roughly $8-10, which is at the lower end of the price range where the majority of emissions from mangroves could be avoided."
The recommendations of the researchers to protect mangroves in order to store "blue" carbon as part of climate policy frameworks resembles current REDD (Reducing Emissions from Deforestation and forest Degradation) strategies.
REDD enables nations to receive financial incentives for reducing deforestation, leading to decreases in carbon emissions.
"Projects that involve and respect local people and that use the market for carbon offsets to fund development and conservation are beginning to emerge," Professor Mark Huxham of Edinburgh Napier University, who was not involved with the study, told BBC News.
"This paper is further encouragement for them to succeed," he said.
Dr. Siikamaki said that "institutional" barriers, although still remaining, should not hinder mangrove conservation.
"Developing programmes to compensate for the CO2 benefits of mangrove conservation could provide an important step towards this goal," he said.