Standard climate models may be underestimating greenhouse gas emissions from thawing permafrost by missing one of the key pathways for carbon dioxide entering the atmosphere, according to new research published earlier this month in the journal Geophysical Research Letters.
By leaving out carbon that is flushed into waterways, then converted to CO2 by sunlight in a process known as photomineralization, models to date may have understated permafrost emissions by up to 14%, Yale Environment 360 reports.
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“Only recently have global climate models included greenhouse gases from thawing permafrost soils,” said University of Michigan environmental scientist Rose Cory, one of the study leads. “But none of them contain this feedback pathway.”
“Scientists have previously been cautious about including photomineralization in their models because it can be difficult to measure exactly how sunlight interacts with soil carbon,” Yale Environment 360 explains. But the study team, working in six Arctic locations, “developed a new tool that uses LED lights to measure the impacts of different wavelengths of light on organic carbon. They were then able to determine how light exposure affects the amount of soil carbon converted to CO2 emissions, as well as other factors that might accelerate the reaction,” like the amount of iron in the soil.
“What we have long suspected is that iron catalyzes this sunlight-driven process, and that’s exactly what our results show,” Cory said. “As the total amount of iron increases, the amount of carbon dioxide increases.”