Global Water Oxygen Levels Falling Rapidly, Researchers Warn of Ecosystem Threat

Scientists from the Scripps Institution of Oceanography and the University of California report that dissolved oxygen in the world’s oceans, lakes and rivers is decreasing at an alarming pace. The study links the decline to rising temperatures, excess nutrient runoff and altered deep‑water circulation, all driven by human activities. Researchers argue that the loss of oxygen could disrupt marine and freshwater food webs from microscopic organisms up to fish and marine mammals, and could undermine processes that regulate Earth’s climate.

The authors propose adding water‑borne oxygen to the Planetary Boundaries framework, noting that the planet’s health “depends on the condition of aquatic ecosystems that need oxygen to function normally.” They warn that continued trends may become irreversible within a human lifetime and urge immediate action to curb emissions, nutrient pollution and other stressors.

The findings underscore a global environmental risk that transcends national borders, calling for coordinated mitigation efforts.