Ancient plant and animal matter trapped within Arctic permafrost can be converted rapidly into climate-warming carbon dioxide when melted and exposed to sunlight, according to a new study.
In a report published Monday in the Proceedings of the National Academy of Sciences, a team of environmental and biological scientists examined 27 melting permafrost sites in Alaska and found that bacteria converted dissolved organic carbon materials into the greenhouse gas CO2 40% faster when exposed to ultraviolet light.
Study authors said that while it remained unclear just how much CO2 would be released as Arctic permafrost continues to melt, the findings were cause for concern. High latitude soils currently store twice the amount of carbon than is found in the atmosphere.
"What we can say now is that regardless of how fast the thawing of the Arctic permafrost occurs, the conversion of this soil carbon to carbon dioxide and its release into the atmosphere will be faster than we previously thought," senior author George Kling, a University of Michigan ecologist and aquatic biogeochemist, said in a statement.
"That means permafrost carbon is potentially a huge factor that will help determine how fast the Earth warms," Kling said.
Plant and animal matter has remained locked in frozen Arctic soils for thousands of years. When those soils begin to thaw, however, the organic matter begins to decay. As that matter decays, it is eaten by microbes, which produce either methane or CO2 as a byproduct. Methane -- an even more powerful greenhouse gas than CO2 -- occurs when the decaying matter is not exposed to oxygen.