Arctic Peat May Release More Methane Than Previously Thought

As Arctic peatlands warm, they're releasing more and more greenhouse gases. Now, scientists have taken a closer look at these normally-frozen regions and have created more accurate models to predict methane emissions and carbon dioxide emissions.

"Peatlands cover about four percent of all land, but they hold 20 percent of all carbon stored on land," said Zhaosheng Fan, the lead researcher, in a news release.

Peatlands are common in the Arctic. Filled with dead and decaying organic matter, these wetlands are the result of millions of years of plants dying and breaking down into rich soil. This means that they contain a massive amount of carbon which is usually locked into the soil by the cold. As the ground warms, though, microbes come to life and decompose the organic matter, which releases carbon into the atmosphere.

In the past, researchers have created models in order to estimate this release. One particular area of interest is in which form the carbon will be released: CO2 or methane. While CO2 is a long-lived greenhouse gas, methane isn't. However, methane has an impact that's about 20 times greater than CO2. Until now, scientists have used a simple model that assumed water was the primary divider; soil above the water table would produce microbes that made CO2 while microbes below would produce methane.

"But experiments had been showing that there could be significant limits on oxygen availability above the water table, and this would affect what form of carbon microbes release," said Fan. "So we set out to make a model that would take these findings into account."

The size and characteristics of soil particles matter. Understanding this, the scientists created a new model that was much more accurate. More specifically, the model suggested that more methane is produced and proportionately less CO2 than predicted by older water table-based models.

"Revising this calculation will substantially affect current greenhouse gas production models in the Arctic," said Fan.

The findings are published in the journal Biogeochemistry.