Melting Arctic Bogs May Hasten Warming, Study Says

December 1, 2004

The Arctic is warming at least twice as fast as the rest of the planet, according to a recent assessment by the Arctic Council, an intergovernmental agency of polar nations and native groups. And within the Arctic, there are regions that are warming more intensely than others. Scientists refer to them as hot spots.

"There's a great big hot spot over western Siberia," said Larry Smith, an associate professor of geography at the University of California (UCLA), Los Angeles.

The presence of the western Siberia hotspot concerns Smith. Earlier this year he published results of a study in the journal Science showing that an area known as the West Siberian Lowland is home to the world's largest peatlands.

Peatlands consist of layer upon layer of partially decomposed plant material. They play a crucial role in governing the atmospheric concentration of the greenhouse gases carbon dioxide and methane, Smith said. Increased concentrations of atmospheric greenhouse gases can accelerate global warming.

Healthy peatlands absorb carbon dioxide as new vegetation grows. But as peatlands incompletely break down, they release methane and carbon dioxide into the atmosphere.

Calculations by Smith and his colleagues show that, over the long term, Siberian peatlands currently have absorbed more greenhouse gasses through plant growth and storage than they have released through decomposition. Thus, the peatlands currently absorb more carbon dioxide than they release.

However, if temperatures in western Siberia continue to rise, its peatlands could thaw and dry out. They would then essentially become giant compost heaps and begin to release vast amounts of carbon dioxide. This could potentially cause a slight acceleration of global warming, Smith said.

Brenda Ekwurzel is a climate scientist with the Union of Concerned Scientists in Washington, D.C. She said the West Siberian Lowland indeed falls within a hot spot but added that whether thawing peatlands will accelerate global warming remains an open question.

Ekwurzel noted, for example, that while the peatlands have the potential to release large quantities of carbon dioxide and methane, changes in the soil and groundwater could lead to increased tree growth, which acts as a carbon sink.

"If it turns out the net impact is increased carbon dioxide and methane emissions to the atmosphere, this would lead to warming and subsequent feedback or amplification cycles," she said.

Hot Spots

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