Wey et al. (2026): CMIP6 Models agree on similar carbon cycle feedbacks between enhancing terrestrial and marine carbon sinks
Hao-Wei Wey, Yiannis Moustakis, Tobias Nützel, Andreas Oschlies, Jörg Schwinger, Tomohiro Hajima, Rosie Fisher, Tilo Ziehn, Spencer K Liddicoat, Tronje Peer Kemena IN: IOP Science, DOI: 10.1088/1748-9326/adc617
In this study, the authors compare two complementary approaches that enhance the terrestrial and marine carbon sinks with afforestation and reforestation (A/R) and ocean alkalinity enhancement (OAE), respectively, under the high emission scenario SSP5-8.5. Eight CMIP6 Earth system models are utilized, enabling a quantification of both inter-model and internal variability. By mid-century, simulated large-scale deployment of A/R and OAE individually reduces atmospheric CO₂ concentrations by up to 20 ppm. For both methods, while carbon removal from the atmosphere is robust, it is difficult to detect the effects on global mean temperature, posing challenges for monitoring, reporting and verification of mitigation efforts. To quantify the carbon cycle feedbacks, we define the carbon cycle feedback ratio of A/R (OAE) as the ratio of changes in the marine (terrestrial) sink to changes in the terrestrial (marine) sink.