Overview
- A peer-reviewed review published June 30 consolidates decades of research showing widespread loss of dissolved oxygen in oceans, coasts, rivers and lakes and argues the problem merits inclusion as a new Planetary Boundary.
- The paper identifies three main human drivers: warmer water holds less oxygen, stronger stratification prevents deep-water ventilation, and excess nitrogen and phosphorus fuel algal blooms that consume oxygen as they decompose.
- European Copernicus data cited in coverage estimate the global ocean has lost about 2% of dissolved oxygen since the 1950s with model projections of an additional 1% to 7% by 2100 under current scenarios.
- Falling oxygen threatens organisms from microbes to fish and marine mammals, can shrink fisheries and alter carbon and nutrient cycling, and the authors warn some impacts may be effectively irreversible within human lifetimes.
- To improve detection and governance the researchers propose four measurable indicators—oxygen concentration, proximity to oxygen capacity, changes in oxygen‑sensitive species, and a Metabolic Index—while noting monitoring and policy response remain fragmented.