Sunlight exposure stimulates conversion of permafrost carbon to CO2

Recent climate change has increased arctic soil temperatures and thawed large areas of permafrost, allowing microbes to convert previously frozen carbon into the greenhouse gas carbon dioxide (CO2).  Furthermore, soil destabilization from melting ice has caused “thermokarst failures,” soil slumping over a large area.  This increases exposure of buried carbon and also releases it to surface waters.  We are working to understand how and how quickly this newly exposed carbon can be converted to CO2.   Our first paper on this process is now published online.   We studied seven thermokarst failures on younger to older landscapes and found that thawed soil carbon in sunlight is at least 40% more susceptible to conversion than carbon still in the dark.

Our study has implications for the debate on how climate change in the Arctic will ultimately affect global temperatures.  We know that permafrost soils have the potential to double the amount of carbon in the atmosphere on a timescale similar to human inputs of greenhouse gases.  What we need to understand are the factors that control the conversion of this carbon once it moves from soils to surface waters, and our study is a step in that direction.