Rivers around the world are gradually losing oxygen due to global warming, posing a threat to fish and aquatic life, according to a recent study. Researchers in China used satellite data and artificial intelligence to study oxygen levels in over 21,000 rivers globally since 1985. The study, published in Science Advances, reveals a 2.1% drop in oxygen levels on average since 1985. This decline, although seemingly small, could harm aquatic ecosystems significantly.
Key chemical and physical processes show that warmer water holds less oxygen. As human-driven climate change raises water temperatures, more oxygen escapes into the atmosphere. If current trends continue, rivers worldwide could lose an additional 4% of their oxygen by century’s end, with some losing nearly 5%, the study indicates.
Lead author Qi Guan from the Chinese Academy of Sciences warns that this deoxygenation could cause major issues for both aquatic life and people dependent on rivers. The decline in oxygen may result in ecological crises, including biodiversity loss and water quality decrease. Recent observations of dead zones in the Gulf of Mexico, Chesapeake Bay, and Lake Erie underline these threats.
University of Arizona geoscientist Karl Flessa predicts an increase in ‘stinky dead zones’ if oxygen levels continue to fall, especially during heatwaves. In extreme cases, even slight changes in temperature may tip some rivers into dangerous zones, significantly impacting fish populations.
Regions of concern include India’s Ganges River, which has experienced oxygen loss over 20 times faster than the global average earlier this century. With moderate emissions scenarios, rivers in the Eastern US, Arctic, India, and South America could see a 10% oxygen reduction by 2100. Notably, the Amazon River faces increased occurrences of dead zones, as shown in recent studies.
Additional reasons for oxygen decline are attributed to nutrient pollution, urban runoff, and dam constructions. However, the study finds that 63% of the problem links back to warming waters. Duke University ecologist Emily Bernhardt highlights the amplified impact of pollution as rivers warm, emphasizing the urgency for stronger water pollution measures.
Leave a Reply