Scientists led by the Scripps Institution of Oceanography at the University of California, San Diego warn that oxygen is rapidly disappearing from oceans and freshwater systems, potentially pushing the planet into “dangerous space.” Some of the resulting changes may persist for centuries and may be irreversible within a human lifetime.
A new review examines aquatic deoxygenation, which refers to the reduction of dissolved oxygen levels in oceans (marine deoxygenation), coastal waters, rivers, lakes, and streams. Researchers assessed how this growing problem interacts with nine major Earth system processes included in the planetary boundaries framework.
Introduced in 2009, the framework identifies environmental processes essential to maintaining a stable and resilient planet. We also track how human activity pushes these systems beyond safe states.
The nine planetary boundaries are climate change, ocean acidification, biodiversity loss, atmospheric aerosol loading, stratospheric ozone depletion, freshwater change, land use change, chemical pollution, and biogeochemical fluxes (including the nitrogen cycle). Researchers argue that dissolved oxygen levels should also be formally included.
“The health and stability of our planet depends on the health and stability of aquatic ecosystems, which require oxygen to function properly,” said lead author Erica Ferrer, a Scripps Oceanography alumnus and now a postdoctoral fellow at the National Center for Ecological Analysis and Integration at the University of California, Santa Barbara. “This study aims to raise awareness that aquatic deoxygenation is a global threat and to show that it does not operate in isolation.”
Oxygen is being lost due to global warming and pollution
Anthropogenic warming, excessive nutrient pollution, and changes in deep water movement and ventilation are the main factors causing aquatic deoxygenation.
Lower oxygen levels can disrupt the biological and chemical processes that control Earth’s climate. This decline also threatens organisms throughout the aquatic food web, from microscopic creatures to fish and sharks.
Marine mammals can suffer even when breathing air at the surface. Loss of oxygen can reduce or displace prey, damage habitat, and alter the food webs upon which they depend.
Linking deoxygenation to other planetary risks
Ferrer and Scripps biological oceanographer Lisa Levin, the study’s lead author, developed the idea for the review after attending the 2019 United Nations climate change conference, COP25, in Madrid.
The researchers hope their findings will encourage researchers and policy makers to examine underwater oxygen loss alongside climate change, pollution, biodiversity loss and other global pressures, rather than treating it as a separate issue.
“Adding aquatic deoxygenation to the planetary boundary framework will help understand its impact on Earth system stability,” Ferrer said. “Reducing that impact is a key element in preserving biodiversity and climate.”
Research support and publication
Feller completed the review during his doctoral studies at Scripps. Her research was supported by the National Science Foundation Graduate Research Fellowship Program, graduate funding from Scripps and the University of California, San Diego, and subsequent postdoctoral support from the University of California, Santa Cruz and the University of California, Santa Barbara.
This study was published in the journal June 30, 2026. Limnology and Oceanography.
Additional authors include former Scripps doctoral students Shaiya Ganglade, Lillian McCormick, and Ariel Pesner, and Yasir Edebbar, now a climate scientist at Scripps. Other contributors are De’Marcus Robinson of UCLA, Véronique Carcon of the Paris Institute of Geophysics, and Kevin Rose of the Rensselaer Polytechnic Institute.
