The interaction of elemental iron with the vast stores of carbon locked away in Arctic soils is key to how greenhouse gases are emitted during thawing and should be included in models used to predict Earth’s climate, Oak Ridge National Laboratory scientists found.
Researchers set out to explore and model the chemistry going on as the Arctic permafrost thaws in response to global warming. Northern permafrost soils contain an estimated 1,460 billion to 1,600 billion metric tons of organic carbon — about twice as much as in the atmosphere, according to the National Oceanic and Atmospheric Administration.
Chemical processes in the soil control how organic matter decomposes and is stored in soils and whether it converts to carbon dioxide or the more powerful greenhouse gas methane when released into the atmosphere.
Arctic soils are typically organic-rich and often have a high iron content, frequently visible as rusty deposits in flooded soils in the region, said ORNL modeler and principal investigator Benjamin Sulman. But current Earth system models do not take iron cycling into account when predicting the climate-warming potential of thawing permafrost.
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