2025/09/30 by Yinghuan Xie, Paul Spence, Stuart Corney +2 · 1 voice
Earth and Planetary Sciences · Environmental Science · #Atmospheric and Environmental Gas Dynamics #Climate variability and models #Oceanographic and Atmospheric Processes
paper · doi:10.1029/2024gb008482
openalex publication_date 2025/09/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22
Abstract Marine Carbon Dioxide Removal (mCDR) will likely play a role in efforts to keep global warming below 2°C. mCDR methods create a deficit in dissolved seawater CO 2 relative to the unperturbed counterfactual. This seawater CO 2 deficit induces either an uptake of atmospheric CO 2 or reduced CO 2 outgassing into the atmosphere. The immediate climatic benefit of mCDR depends on air‐sea CO 2 equilibration before the CO 2 depleted seawater deficit in the surface ocean loses contact with the atmosphere through water mass ventilation. Air‐sea CO 2 equilibration occurs over vast ocean regions, which are too large to constrain equilibration with current observational methods. As such, numerical modeling is needed to evaluate the spatial and temporal scales of air‐sea CO 2 equilibration. This study employs the ACCESS‐OM2 model at three resolutions (0.1°, 0.25°, and 1°) to evaluate the dependency of simulated equilibration timescales on model resolution. Results indicate that model resolution has limited influence on equilibration timescales in the tropics but exerts a more significant effect in polar regions. The main reason for the simulated differences is that different resolutions advect CO 2 ‐deficient seawater into different locations (horizontally and vertically) where air‐sea exchange can occur at different rates. The comparison of our results with simulations made with other ocean models further suggests that differences due to model resolution are smaller than differences between different models of similar resolutions. Our results are one step forward in evaluating the robustness of model‐based assessments of air‐sea CO 2 equilibration timescales.