By SETH BORENSTEIN / AP, Washington
Global warming is causing rivers to slowly lose oxygen, threatening fish and other lives in the waterways, a new study shows.Researchers in China used satellites and artificial intelligence to track and analyze oxygen levels in more than 21,000 rivers across the globe since 1985. They found oxygen levels have dropped an average of 2.1 percent since 1985, according to a study published in Science Advances. That does not seem like much but it adds up and if it continues or accelerates, rivers in the eastern US, India and across the tropics could lose enough oxygen by the end of the century to suffocate fish and create dead zones, the study said.Chemistry and physics dictate that warmer water holds less oxygen, scientists said. Warmer water, which happens with human-caused climate change, releases more oxygen into the atmosphere.
A fisherman walks to his boat in Santa Rosa, Peru, an island on the Amazon River, on Aug. 17, 2025.
If the oxygen loss rate continues at the current pace, the world’s rivers on average could lose an additional 4 percent of their oxygen by the end of the century — in some cases close to 5 percent — the study found. That is when oxygen loss — called deoxygenation — becomes problematic for fish and people who rely on rivers, according to the study’s lead author Qi Guan, an environmental scientist at the Chinese Academy of Sciences in Nanjing.MORE DEAD ZONES
