Wetlands a ticking 'carbon bomb'
2008-07-21 19:13
Washington - The world's wetlands,
threatened by development, dehydration and climate change,
could release a planet-warming "carbon bomb" if they are
destroyed, ecological scientists said on Sunday.
Wetlands contain 771 billion tonnes of greenhouse gases,
one-fifth of all the carbon on Earth and about the same amount of
carbon as is now in the atmosphere, the scientists said before an
international conference linking wetlands and global warming.
If all the wetlands on the planet released the carbon they
hold, it would contribute powerfully to the climate-warming
greenhouse effect, said Paulo Teixeira, coordinator of the
Pantanal Regional Environment Program in Brazil.
"We could call it the carbon bomb," Teixeira said by
telephone from from Cuiaba, Brazil, site of the conference.
"It's a very tricky situation."
Carbon storage
Some 700 scientists from 28 nations are meeting this week
at the Intecol International Wetlands Conference at the edge of
Brazil's vast Pantanal wetland to look for ways to protect
these endangered areas.
Wetlands are not just swamps: they also include marshes,
peat bogs, river deltas, mangroves, tundra, lagoons and river
flood plains.
Together they account for 6 percent of Earth's land surface
and store 20% of its carbon. They also produce 25% of the world's food, purify water, recharge aquifers
and act as buffers against violent coastal storms.
Historically, wetlands have been regarded as an impediment
to civilisation.
About 60% of wetlands worldwide have
been destroyed in the past century, mostly due to draining for
agriculture.
Pollution, dams, canals, groundwater pumping,
urban development and peat extraction add to the destruction.
Image problem
"Too often in the past, people have unwittingly considered
wetlands to be problems in need of a solution, yet wetlands are
essential to the planet's health," said Konrad Osterwalder, UN
Under Secretary-General and rector of United Nations
University, one of the hosts of the meeting.
So far, the impacts of climate change are minor compared to
human depredations, the scientists said in a statement.
As is
the case with other environmental problems, it is far easier and
cheaper to maintain wetlands than try to rebuild them later.
As the globe warms, water from wetlands is likely to
evaporate, rising sea levels could change wetlands' salinity or
completely inundate them.
Even so, wetland rehabilitation is a viable alternative to
artificial flood control for coping with the larger, more
frequent floods and severe storms forecast for a warmer world.
Frozen soil
Northern wetlands, where permanently frozen soil locks up
billions of tonnes of carbon, are at risk from climate change
because warming is forecast to be more extreme at high
latitudes, said Eugene Turner of Louisiana State University, a
participant in the conference.
The melting of wetland permafrost in the Arctic and the
resulting release of carbon into the atmosphere may be
"unstoppable" in the next 20 years, but wetlands closer to the
equator, like those in Louisiana, can be restored, he said.
Teixeira admitted wetlands have an image problem with the
public, which is generally well-disposed to saving the
rainforest but not the swamp.
"People don't have a good impression about wetlands,
because they don't know about the environmental service that
wetlands provide to us," he said.