July 21, 2008

Destruction Of Wetlands May Cause “Carbon Bomb”

Threatened by climate change, development and dehydration, wetlands throughout the world could release a "carbon bomb" if they are destroyed, scientists reported Sunday.

These wetlands contain 771 billion tons of greenhouse gases, 20 percent of all the carbon on Earth and about the same amount of carbon as is now in the atmosphere, the ecologists told an international conference.

If all the wetlands on the planet released their carbon, it would substantially increase the climate-warming greenhouse effect, according to Paulo Teixeira, coordinator of the Pantanal Regional Environment Program in Brazil.

"We could call it the carbon bomb," Teixeira told Reuters during a telephone interview from Cuiaba, Brazil, where the conference is being held.

"It's a very tricky situation."

Nearly 700 scientists from 28 countries are convening this week at the INTECOL International Wetlands Conference to search for ways to protect the endangered wetlands.

The wetlands are not merely swamps, but also include river deltas, marshes, mangroves, peat bogs, tundra, lagoons and river flood plains, which together account for 6 percent of the planet's land surface and store 20 percent of its carbon.   Furthermore, they produce one quarter of the world's food, purify water, recharge aquifers and buffer violent coastal storms.

Wetlands have traditionally have been viewed as an impediment to civilization.  Indeed, nearly 60 percent of the planet's wetlands have been destroyed in the past 100 years, mostly due to agriculture draining.   Dams, Pollution, urban development, canals, groundwater pumping and peat extraction have each contributed to the destruction.

"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," Konrad Osterwalder, UN Under Secretary-General and director of UN University, told Reuters.

In a statement, the ecologists said the impacts of climate change, to date, are minor compared to human depredations.  As with other environmental challenges, it is far better to maintain the wetlands than attempt to rebuild them later, they said.

As the planet warms, water from wetlands will likely evaporate, and rising sea levels could change the salinity of the wetlands or completely overwhelm them. Nevertheless, wetland rehabilitation is a viable alternative to artificial flood control for managing the larger, more frequent floods and severe storms predicted for a warmer planet.

Northern wetlands, where billions of tons of carbon are stored in permanently frozen soil, are at risk as global warming is thought to be more extreme at high latitudes, according to conference participant Eugene Turner of Louisiana State University.

The melting of Arctic wetland permafrost and the subsequent release of carbon into the atmosphere may be "unstoppable" in the next two decades. However,  wetlands closer to the equator, such as those in Louisiana, can be restored, Turner told Reuters.

Teixeira acknowledged wetlands have a public image problem, and that people generally favor 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.


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