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Monday, October 13, 2008

Rising Temperatures May Dry Up Peat Bogs, Causing Carbon Release

Rising Temperatures May Dry Up Peat Bogs, Causing Carbon Release

by Henry Fountain, New York Times, October 13, 2008

It’s increasingly clear that the effects of climate change will be felt — or are already being felt — in all corners of the globe, in all kinds of ecosystems.

Even, it appears, in peat bogs. A study in Nature Geoscience suggests that northern bogs may lose a significant portion of their peat as global temperatures rise. Organic matter in the peat will decompose, releasing carbon into the atmosphere.

Ordinarily peat bogs are a huge carbon sink. They consist of marsh grasses, trees and other organic matter that, because of the wet, oxygen-starved conditions, don’t decay much. What’s more, peat generally begets more peat: because it holds so much water and blocks drainage, as it accumulates the water table rises, reducing decay even further.

This water table-peat interaction is what scientists call a positive feedback loop. Takeshi Ise of the Japan Agency for Marine-Earth Science and Technology and colleagues looked at what would happen to this process when environmental conditions change.

Using data from bogs in northern Manitoba, the researchers simulated the effects of warming by 7 F. They found that higher temperatures would in effect reverse the feedback loop: the water table would drop, causing more peat to dry and decompose.

Over hundreds of years, their simulation suggests, 40% of organic carbon could be lost from bogs where the peat layer is shallow, while in deep bogs, the losses would be as much as 86%.

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