Will open ocean oxygen stress intensify under climate change

Abstract Global warming is expected to reduce oxygen solubility and vertical exchange in theocean, changes which would be expected to result in an increase in the volume ofhypoxic waters. A simulation made with a full earth system model with dynamical 5 atmosphere, ocean, sea ice and biogeochemical cycling shows that this holds true ifthe condition for hypoxia is set relatively high. However, the volume of the most hypoxicwaters does not increase under global warming, as these waters actually become moreoxygenated. We show that the rise in oxygen is associated with a drop in ventilationtime. A term-by-term analysis within the least oxygenated waters shows an increased 10 supply of oxygen due to lateral diffusion. compensating an increase in remineralizationwithin these highly hypoxic waters. This lateral diffusive flux is the result of an increaseof ventilation along the Chilean coast, as a drying of the region under global warmingopens up a region of wintertime convection in our model. 1 Introduction