资源环境科技发展态势分析平台

Ocean deoxygenation is an emerging hazard for marine ecosystems and a fingerprint of anthropogenic change. Interior ocean oxygen concentrations respond to changes in ventilation that supply oxygen and the demand of biogeochemical processes that consume oxygen. A better understanding of their regional importance would improve confidence in Earth System Model projections, which underpin ecosystem risk and vulnerability assessments. Using a hindcast reanalysis simulation, we find that oxygen trends between 1975-2014 in low-oxygen zones along eastern margins are strongly affected by biogeochemical process that alter oxygen demand, while oxygen-rich regions of the open ocean are driven by ventilation changes. A similar regional distinction emerges among CMIP6 Earth System models. Therefore, while biogeochemical functioning is an important source of uncertainty in low-latitude, low-oxygen regions, uncertainty in global trends is due to insufficient physical supply changes in Earth System Models, which is confirmed using repeat hydrographic section data in the southern mid-latitudes.