Arctic Amplification of Global Warming Strengthened by Sunlight Oxidation of Permafrost Carbon to CO<sub>2</sub>
Jennifer C. Bowen, Collin P. Ward, George W. Kling, Rose M. Cory
Abstract
Abstract Once thawed, up to 15% of the ∼1,000 Pg of organic carbon (C) in arctic permafrost soils may be oxidized to carbon dioxide (CO 2 ) by 2,100, amplifying climate change. However, predictions of this amplification strength ignore the oxidation of permafrost C to CO 2 in surface waters (photomineralization). We characterized the wavelength dependence of permafrost dissolved organic carbon (DOC) photomineralization and demonstrate that iron catalyzes photomineralization of old DOC (4,000–6,300 a BP) derived from soil lignin and tannin. Rates of CO 2 production from photomineralization of permafrost DOC are twofold higher than for modern DOC. Given that model predictions of future net loss of ecosystem C from thawing permafrost do not include the loss of CO 2 to the atmosphere from DOC photomineralization, current predictions of an average of 208 Pg C loss by 2,299 may be too low by ~14%.