Biblioteca

The ocean enabled the diversification of life on Earth by adding O₂ to the atmosphere, yet marine species remain most subject to O₂ limitation. Human industrialization is intensifying the aerobic challenges to marine ecosystems by depleting the ocean's O₂ inventory through the global addition of heat and local addition of nutrients. Historical observations reveal an ∼2% decline in upper-ocean O₂ and accelerating reports of coastal mass mortality events. The dynamic balance of O₂ supply and demand provides a unifying framework for understanding these phenomena across scales from the global ocean to individual organisms. Using this framework, we synthesize recent advances in forecasting O₂ loss and its impacts on marine biogeography, biodiversity, and biogeochemistry. We also highlight three outstanding uncertainties: how long-term global climate change intensifies ocean weather events in which simultaneous heat and hypoxia create metabolic storms, how differential species O₂ sensitivities alter the structure of ecological communities, and how global O₂ loss intersects with coastal eutrophication. Projecting these interacting impacts on future marine ecosystems requires integration of climate dynamics, biogeochemistry, physiology, and ecology, evaluated with an eye on Earth history...