Marshes

Preserving forests is often billed as one of the best ways to counter climate change because of the trees' carbon-storing properties. But experts say that another natural habitat plays an equally important role in combating global warming but is often ignored - marshes.

"Unfortunately, people are often unaware of the significance of marshes for the climate," John Couwenberg, a researcher at the University of Greifswald in eastern Germany, said.

Bogs and marshlands make up just about three percent of the world's area but they play an important role in stabilizing temperatures because they store more carbon dioxide than all the forests in the world combined.

Marshlands are mainly found in temperate climate zones between the 50th and 70th latitudes. Russia alone is home to a fifth of the world's wetlands. Large marshlands are also found in Canada, Scandinavia, in the Amazon Basin and southeast Asia. Couwenberg said it's believed that Africa too has large wetlands - for instance in the Congo basin and the Niger Delta.

Marshlands are formed when the ground is permanently flooded, as in the vicinity of river banks or when snow melts. A lack of oxygen in the water means that dead plants decay slower than the rate at which new ones grow above the surface.

That leads to a build-up of peat, which takes over the carbon dioxide previously stored in the plants. Healthy peat absorbs and stores carbon; but as it degrades, the carbon is released, ending up in the atmosphere as carbon dioxide.

The peat layer in the world's bogs grows at an average rate of a millimeter a year, storing around 150 to 250 tons of carbon dioxide in the ground.

Natural climate-killers

Marshlands have been drained by humans for centuries to make way for farms or to gather wood and other construction materials. That leads to the degrading of the peat layer, releasing the stored carbon and thus turning the large carbon sink into a dangerous greenhouse gas emitter.

"Around the world, around ten percent of all marshlands have been degraded through draining," Couwenberg said. It's estimated the resulting release of peat leads to carbon emissions of two billion tons a year.

And they're far more harmful than the one-off carbon dioxide emissions resulting from deforestation. The drying-up of marshes releases carbon for as long as it takes for the peat to degrade. The process can take several centuries depending on the thickness of the peat layer.

Carbon emissions from drained marshlands has risen by 20 percent worldwide in the last 20 years and developing countries contribute hugely to it.

Indonesia has one of the most extensive marshland degradations in the world because entire peat forests in the country have been drained to cultivate oil palms, rice or aloe vera.

Huge forest fires regularly break out on the dried up peat, making Indonesia the world's worst polluter when it comes to marshland-related emissions

Shift in attitudes

But a lot of countries have now realized the significant role of bogs in combating climate change and many have begun efforts to revive the wetlands.

Projects are underway in Belarus, the US, Canada, Germany and Russia where a huge marshland has been designated a protected zone.

Vera Luthardt of the German Society for Marshes and Peat Research said restoring marshlands often doesn't take much more than filling up drained land.

"The first marsh plants such as reeds, moss and sedges often grow within just two or three years," Luthardt said, adding that it however takes up to 15 years for the peat to grow again.

Experts say alternative use of marshlands is a must, if they are to play a role in curbing climate change in the future.

And that would involve economic advantages too, such as using the reedbeds in marshlands to generate biomass energy or using efficient modern irrigation techniques.

"There are plenty of ways to protect marshlands and the technology is available as well," said Luthardt. "But implementation and political conditions are often problematic."

But politicians might act more quickly to rectify that if they considered that yearly carbon emissions from dried-out marshlands far outstrip emissions produced by traffic worldwide.

Author: Janine Rabe (sp)
Editor: Mark Mattox