A Plea for Temperature in Descriptions of the Oceanic Oxygen Status

Kurzfassung

For over 50 years, the ocean science community has traditionally reported hypoxic limits form marine animals simply as a concentration value independent of temperature and pressure, implying the same limit for the warmest shallow gulf or the coldest deep fjord. Similarly, deep-sea oxygen consumption rates are typically reported as exponential functions of depth. In implicitly combining temperature, pressure, and multiple other properties into a single variable, it becomes difficult to describe the future of an ocean under changing climate conditions. We report here on a series of recent papers that seek to provide improved descriptions, by mapping the ocean pO2 field and then matching it to the various concentration limits proposed. We describe the availability of O2 to marine animals as being governed by a diffusive boundary rate process similar to well-known descriptions of air-sea gas exchange. We also describe the challenge for a deep-sea animal exporting CO2 through the same boundary layer with known chemical reactivity imposed. The end result is a clear sense that ocean warming in most regions will add stress to the aerobic functioning of marine life, that the oxygen minimum zones appear to be more challenging than ever, and that the deepest abyssal ocean will retain quite favorable aerobic conditions.