Yet these same peatlands are credited with converting another greenhouse gas, carbon dioxide, into harmless carbon held in the soil. Because peatland vegetation doesn't properly decompose, much of the carbon dioxide taken in by living plants isn't returned to the air.
The new study suggests the West Siberian Lowland alone accounts for between 7 to 26 percent of global carbon reserves accumulated since the last Ice Age. Globally, peatlands contain an estimated 550 billion tons (541 billion metric tons) of stored carbon. If this carbon sink were released back into the atmosphere as carbon dioxide gas, the consequences could be dire.
Signs in northern Russia indicate this process may be about to start.
Smith said: "Sea ice is melting so quickly that it's at the lowest extent ever seen before. Shrubs are sprouting up in what used to be tundra. The growing season has lengthened, and the tree line may even be moving north. Studies have shown that permafrost is degrading at its southern boundaries, and permafrost temperatures are rising further north. There's no question that the Arctic is really heating up."
Similar concerns exist in other countries. At an international climate change conference in Milan, Italy, last month, the conservation group Wildlife Habitat Canada warned that climate change modeling studies forecast very severe effects on peatlands in the mid-belt of Canada. Peatlands cover 12 percent of the country.
The UCLA-led team says warmer temperatures, coupled with melting permafrost and a lowered water table, could eventually lead to aerobic decomposition due to peatland drying and increased soil oxygen levels. As a result, carbon dioxide would be produced instead of methane. They calculated that the long-term benefits of lower levels of methane (which has a shorter lifetime in the atmosphere) could be significantly outweighed by the increase in carbon dioxide, leading to "a positive warming impact to the atmosphere."
Smith added: "Since we focus so much today on manmade sources of greenhouse gases, it's easy to forget that global climate changes also occur naturally. But we're in uncharted territory when it comes to combining manmade sources with natural sources."
Smith cautions that if the Siberian peatlands, with 11,500 years' worth of carbon dioxide stored in them, start to rot away, we could be in for a shock.
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