Page last updated at 11:54 GMT, Tuesday, 22 July 2008 12:54 UK

Warming world 'drying wetlands'

Lone plant in dried-out swamp (Getty Images)
Drained wetlands could release vast amounts of carbon into the atmosphere

More than 700 scientists are attending a major conference to draw up an action plan to protect the world's wetlands.

Organisers say a better understanding of how to manage the vital ecosystems is urgently needed.

Rising temperatures are not only accelerating evaporation rates, but also reducing rainfall levels and the volume of meltwater from glaciers.

Although only covering 6% of the Earth's land surface, they store up to an estimated 20% of terrestrial carbon.

Co-organised by the UN University and Brazil's Universidade Federal de Mato Grosso, the five-day Intecol International Wetlands Conference in Cuiaba, Brazil, will examine the links between wetlands and climate change.

"Humanity in many parts of the world needs a wake-up call to fully appreciate the vital environmental, social and economic services wetlands provide," said conference co-chairman Paulo Teixeira.

These included absorbing and holding carbon, regulating water levels and supporting biodiversity, he added.

Konrad Osterwalder, rector of the UN University, said that people in the past had viewed the habitats as a problem, which led to many being drained.

"Yet wetlands are essential to the planet's health," he explained. "With hindsight, the problems in reality have turned out to be the draining of wetlands and other 'solutions' we humans devised."

Under pressure

Scientists warn that if the decline of the world's wetlands continued, it could result in vast amounts of carbon being released into the atmosphere and "compound the global warming problem significantly".

Wetlands act as sponges and their role as sources, reservoirs and regulators of water is largely underappreciated
Professor Wolfgang Junk,
Max Planck Institute

It is estimated that drained tropical swamp forests release 40 tonnes of carbon per hectare each year, while drained peat bogs emit between 2.5 to 10 tonnes.

Data shows that about 60% of wetlands have been destroyed in the past century, primarily as a result of drainage for agriculture.

"Lessening the stress on wetlands caused by pollution and other human assaults will improve their resilience and represents an important climate change adaption strategy," explained Wolfgang Junk from the Max Planck Institute for Evolutionary Biology, Germany.

"Wetlands act as sponges and their role as sources, reservoirs and regulators of water is largely underappreciated," Professor Junk added.

"They also cleanse water of organic pollutants, prevent downstream flood inundations, protect river banks and seashores from erosion, recycle nutrients and capture sediment."

The conference organisers said the ecosystems, many of which have biodiversity that rivals rainforests and coral reefs, were in need of complex long-term management plans.

They hope the scientific meeting, which ends on Friday, will highlight the range of measures needed, such as agreements that covered the entire catchment areas of the wetlands.

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