WASHINGTON — A new global study has found that climate change is steadily lowering oxygen levels in rivers around the world, raising risks for fish, freshwater ecosystems, and communities that depend on them.
Researchers in China analyzed more than 21,000 rivers globally using satellite data and artificial intelligence, tracking oxygen trends since 1985. Their findings, published in the journal Science Advances, show that river oxygen levels have declined by an average of 2.1 percent over the period.
While the decline may appear modest, scientists warn it is enough to significantly disrupt aquatic ecosystems if the trend continues or accelerates.
The study explains that rising global temperatures are a major driver of oxygen loss in rivers. Warmer water naturally holds less dissolved oxygen, a basic principle of physics and chemistry. At the same time, warming water increases oxygen release into the atmosphere, further reducing levels available for aquatic life.
The study projects that if current conditions persist, rivers could lose an additional 4 percent of their oxygen by the end of the century, with some regions approaching 5 percent loss. Researchers say this level of “deoxygenation” could push many ecosystems toward critical stress, including fish die-offs and the formation of low-oxygen “dead zones.”
Lead author Qi Guan, an environmental scientist at the Chinese Academy of Sciences in Nanjing, said the process is gradual but dangerous over time. He warned that prolonged oxygen decline could trigger biodiversity loss, worsening water quality, and large-scale ecological disruption.
Independent experts not involved in the study said the findings align with earlier research showing increasing oxygen stress in freshwater systems. They noted that warming intensifies the impact of existing pollution, making rivers more vulnerable to low-oxygen conditions during heat waves.
The study also identified additional contributors to oxygen decline, including nutrient pollution from fertilizers and urban runoff, as well as dam construction and changes in river flow patterns. However, researchers found that nearly 63 percent of the oxygen loss is directly linked to rising water temperatures associated with human-driven climate change.
This link to climate change is critical, as scientists emphasize that greenhouse gas emissions from burning fossil fuels are driving global warming, which in turn heats rivers and accelerates oxygen depletion. As emissions continue to rise, river systems in regions such as Eastern United States, India, the Arctic, and parts of South America are expected to experience sharper declines in oxygen levels.
Previous research has also shown that some of the world’s major rivers, including the heavily polluted Ganges in India, have experienced rapid oxygen loss, with impacts far above the global average in past decades.
Experts warn that tropical rivers, including systems like the Amazon, may be especially vulnerable due to already high temperatures and increasing climate stress.
Scientists caution that as warming continues, the combined effects of pollution and rising temperatures could make river ecosystems increasingly fragile, with long-term consequences for biodiversity, fisheries, and freshwater resources.
Paraluman P. Funtanilla
Paraluman P. Funtanilla is Tutubi News Magazine's Marketing Specialist and is a Contributing Editor. She finished her degree in Communication Arts in De La Salle Lipa. She has worked as a Digital Marketer for start-up businesses and small business spaces for the past two years. She has earned certificates from Coursera on Brand Management: Aligning Business Brand and Behavior and Viral Marketing and How to Craft Contagious Content. She also worked with Asia Express Romania TV Show.
- Paraluman P. Funtanilla
- Paraluman P. Funtanilla
- Paraluman P. Funtanilla
- Paraluman P. Funtanilla
