Climate change models have underestimated the amount of carbon dioxide that will be emitted from thawing permafrost by as much as 14 percent, according to a new study published in the journal Geophysical Research Letters. The research incorporates a key pathway for CO2 to enter the atmosphere that is missing from other models: when carbon from thawing permafrost is flushed into waterways and converted to CO2 by sunlight.
Scientists estimate there are about 1,500 billion metric tons of carbon locked away in Arctic permafrost, and that 5 to 15 percent of this carbon could be emitted as carbon dioxide by 2100 — enough to increase global temperatures 0.3 to 0.4 degrees Celsius. But these estimates do not include the CO2 that forms when permafrost carbon escapes into Arctic lakes and rivers and is oxidized by ultraviolet and visible light, a process known as photomineralization.
Researchers at the University of Michigan studied organic carbon from six different Arctic locations and found that substantial carbon dioxide emissions could be released through photomineralization — enough to raise permafrost-related CO2 emissions by 14 percent.