Global Water Deoxygenation Study Highlights Planetary Threat

New research indicates a continuous decline of dissolved oxygen in oceans, seas, lakes and rivers, branding water deoxygenation as one of the most severe environmental threats to the planet. Scientists from the Scripps Institution of Oceanography and a team led by the University of California, San Diego argue that the loss of oxygen should be added as a distinct planetary boundary alongside climate change, biodiversity loss and other key Earth-system processes.

The studies identify three primary drivers: rising global temperatures that reduce oxygen solubility, nutrient pollution from excess nitrogen and phosphorus that fuels algal blooms, and alterations in oceanic and freshwater currents that limit oxygen transport to deeper waters. Since the 1970s, dissolved‑oxygen levels have dropped about 2%, creating expanding “dead zones” where most aquatic life cannot survive. Over 200 locations worldwide, especially near the poles and in the Pacific, Indian and Atlantic oceans, now show persistent low‑oxygen conditions, threatening biodiversity, fisheries and marine mammals.

Researchers warn that continued deoxygenation could disrupt critical biogeochemical cycles, diminish food resources and exacerbate climate feedbacks, underscoring the urgency of mitigating climate change and nutrient runoff.