Wetlands to Blame for Sudden Greenhouse Gas Emissions of Methane

It turns out that wetlands may be to blame for more greenhouse gas than previously thought. Scientists have discovered that a recent rise in atmospheric methane may actually stem from wetland emissions.

Methane is one of the strongest greenhouse gases, and can come from agriculture, fossil fuel use, and natural resources such as microbes in wetland soils. The amount of methane in the atmosphere has actually remained relatively stable for about a decade. But in 2007, levels started to rise again. This rise was suspected to be from thawing northern wetlands.

In order to find out the true source of these emissions, the researchers looked at almost 20,000 field data measurements collected from 70 sites across the artic, temperature and tropical regions. This allowed them to assess the areas where the methane was coming from.

"Our analyses show that northern fens, such as those created when permafrost thaws, can have emissions comparable to warm sites in the tropics, despite their cold temperatures," said Agnieszka Kotowska, one of the researchers, in a news release. "That's very important when it comes to scaling methane release at a global scale."

In fact, small temperature changes can release much more methane from wetland soils into the atmosphere. This can then exacerbate the global warming problem.

"Not only are fens one of the strongest sources of wetland greenhouse gases, but we also know that Canadian forests and tundra underlain by permafrost are thawing and creating these kinds of high methane-producing ecosystems," said Kotowska in a news release.

The findings reveal how important it is to understand what areas are most likely to give off methane. Learning regions that are at risk could allow researchers to develop ways to curb this release. In addition, the study highlights the importance of detecting different types of wetlands and methane release rates between flooded and drained areas.

The findings are published in the journal Global Change Biology.