Earth’s waters are quietly running out of oxygen, scientists warn
A new review warns that oxygen levels in oceans and freshwater systems are declining rapidly due to human-caused warming and nutrient pollution. Scientists argue that aquatic deoxygenation should be formally recognized as a critical planetary boundary to prevent irreversible ecological damage.
Why it matters
Declining oxygen levels threaten the stability of global aquatic ecosystems, which are essential for climate regulation and biodiversity.
Scientists led by UC San Diego's Scripps Institution of Oceanography are warning that oxygen is disappearing rapidly from oceans and freshwater systems, potentially pushing the planet into an "unsafe space." Some of the resulting changes could persist for centuries and may not be reversible within human lifetimes.
The new review examines aquatic deoxygenation, which refers to declining levels of dissolved oxygen in the ocean (ocean deoxygenation), coastal waters, rivers, lakes and streams. The researchers assessed how this growing problem interacts with the nine major Earth system processes included in the Planetary Boundaries framework.
Introduced in 2009, the framework identifies environmental processes that are essential for maintaining a stable and resilient planet. It also tracks how human activity is pushing those systems beyond safe conditions.
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