Scripps-led review calls for aquatic deoxygenation to be recognized as a critical planetary process under threat. Scripps-led review calls for aquatic deoxygenation to be recognized as a critical planetary process under threat. The study reviews the widespread interactions between aquatic deoxygenation — the decline of dissolved oxygen in the ocean (ocean deoxygenation), coastal waters, rivers, lakes and streams — and the nine processes outlined by the Planetary Boundaries framework. The nine planetary boundaries are climate change, ocean acidification, biodiversity loss, atmospheric aerosol loading, stratospheric ozone depletion, freshwater change, land-use change, chemical pollution and biogeochemical flows (including the nitrogen cycle). The authors propose adding dissolved oxygen conditions to the framework.