Mangroves shield against global warming
Mangroves, which have declined by up to half over the last 50 years,
are an important bulkhead against climate change, a study released on
Sunday has shown for the first time.
Destruction of these tropical coastal woodlands accounts for about 10
percent of carbon dioxide emissions from deforestation, the second
largest source of CO2 after fossil fuel combustion, the study found.
Declining Mangroves: Google |
Fewer trees not only mean less CO2 absorbed from the air, but also
the release of carbon stocks that have been accumulating in
shallow-water sediment over millennia.
Mangroves - whose twisted, exposed roots grace coastlines in more
than 100 countries - confer many benefits on humans living in their
midst..
The brackish tidal waters in which the trees thrive are a natural
nursery for dozens of species of fish and shrimp essential to commercial
fisheries around the world.
Another major "ecosystem service," in the jargon of environmental
science, is protection from hurricanes and storm surges.
Cyclone Nargis, which killed 138,000 people in Myanmar in 2008, would
have been less deadly, experts say, if half the country's mangroves had
not been ripped up for wood or to make way for shrimp farms.
Daniel Donato of the US Department of Agriculture's Forest Service in
Hilo, Hawaii and an international team of researchers examined the
carbon content in 25 mangroves scattered across the Indo-Pacific region.
The trees stored atmospheric CO2 just as well as land-based tropical
forests, they found. Below the water line, they were even more
efficient, hoarding five times more carbon over the same surface area.
"Mangroves are among the most carbon-rich forests in the tropics,"
Donato and his colleagues said in the study, published in Nature
Geoscience.
"Our data show that discussion of the key role of tropical wetland
forests in climate change could be broadened significantly to include
mangroves."
AFP |