Drought-induced peatland carbon loss exacerbated by elevated CO <sub>2</sub> and warming
Quan Quan, Jian Zhou, Paul J. Hanson, Daniel Ricciuto, Stephen D. Sebestyen, David J. Weston, Jeffrey P. Chanton, Rachel Wilson, Joel E. Kostka, Yu Zhou, Ning Wei, Lifen Jiang, Melanie A. Mayes, Jonathan M. Stelling, Andrew D. Richardson, Mirindi Eric Dusenge, Danielle A. Way, J. M. Warren, Yiqi Luo
Abstract
Extreme drought events are predicted to increase with climate change, yet their impacts on ecosystem carbon dynamics under warming and elevated carbon dioxide (eCO 2 ) remain unclear. In a peatland experiment with five warming treatments each under ambient carbon dioxide (aCO 2 ) and eCO 2 (+500 parts per million), a 2-month extreme drought in 2021 reduced net ecosystem productivity by 444.0 ± 65.8 and 736.6 ± 57.8 grams of carbon per square meter at +9°C under aCO 2 and eCO 2 , respectively—228.6 ± 56.8% and 381.9 ± 83.4% of the reduction at +0°C under aCO 2 . This exacerbation was driven by warming-induced water table decline, prolonged low water tables, and CO 2 -enhanced substrate availability through increased plant carbon inputs. Findings indicate that future climate will greatly amplify carbon loss during extreme drought, reinforcing positive carbon-climate feedbacks.