Strong Nonlinearity of Land Climate‐Carbon Cycle Feedback Under a High CO ₂ Growth Scenario

Projections of future climate change for given CO2 and other greenhouse gas emission scenarios depend on the response global climate-carbon cycle feedback, which consists carbon-concentration feedback (e.g., physiology effect land carbon sink) carbon-climate radiative sink). Previous studies have assumed no significant interaction between these two feedbacks within Earth system. This study quantifies feedbacks, or nonlinear using fully, biogeochemically, radiatively coupled simulations under a 1% yr−1 increase path from nine system models Coupled Model Intercomparison Project Phase 6 (CMIP6). The results show that is 1.64 ± 2.92 × 10−2 GtC ppm−1 K−1 at end 140-year simulation with quadrupling (4 CO2), where its strength 11% 18% −27% 49% land. Compared to previous assumptions did not consider this interaction, contributes about 8% 12% accumulated 4 CO2. largely combined increased CO2-induced additional fertilization warming-induced leaf area index vegetation productivity over Northern Hemisphere. magnitude decreases an in atmospheric warming high scenario. highlights significance increasing sink slowing down change.