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Scientists Find Climate Change Is Reducing Oxygen In Rivers Worldwide
A new study finds that warming water reduces oxygen levels in rivers around the world, threatening fish and people who depend on these waterways. The researchers project an average 4% additional oxygen loss by the century’s end, with some regions approaching 5%, driven mainly by warmer water and aided by pollution and dam effects.
Why It Matters
Deoxygenation could lead to dead zones and broader ecological crises in rivers, impacting biodiversity, water quality, and fisheries that billions rely on for sustenance and livelihoods.
Timeline
5 Events
Experts discuss ecological and policy implications
May 16, 2026
Duke University ecologist Emily Bernhardt notes that as rivers warm, pollution problems become more damaging to oxygen levels; University of Arizona geoscientist Karl Flessa warns of more dead zones during heat waves; Utrecht University hydrology professor Marc Bierkens notes rising oxygen stress and dead zone occurrences as the climate continues to warm.
Dead zones in rivers could threaten fish and river communities
May 16, 2026
Experts warn that oxygen loss could create dead zones in rivers, similar to those seen in the Gulf of Mexico, Chesapeake Bay, and Lake Erie, affecting fish and people who rely on waterways.
New study links warming to reduced river oxygen; projections
May 16, 2026
Qi Guan, environmental scientist at the Chinese Academy of Sciences in Nanjing, led a study finding that warmer water reduces dissolved oxygen in rivers worldwide. The project projects an average global oxygen loss of about 4% by the end of the century, with some regions near 5%. Warmer water is identified as the main driver, accounting for about 63% of the loss, with nutrient pollution from fertilizer and urban runoff, dam construction, and flow and wind effects contributing as well.
2025 study on global oxygen stress and dead zones
2025
A study by Marc Bierkens and colleagues published in 2025 found oxygen stress in the world's rivers increased by about 13 days per decade, and dead zone occurrences rose by nearly three days per decade since 1980.
Amazon dead zones rise since 1980
1980
The article cites a study noting that since 1980 the number of days with dead zone spots in the Amazon River rose by nearly 16 days per decade, illustrating long-term oxygen stress in tropical rivers.