Climate change depleting oxygen levels in rivers worldwide: Study

Oxygen levels in rivers across the globe are declining at an alarming rate, with rising global temperatures driven by climate change identified as the primary cause, according to a new international study.

Researchers warn that the trend could pose a serious threat to freshwater biodiversity and river ecosystems worldwide.

The study was conducted by scientists from the Nanjing Institute of Geography and Limnology under the Chinese Academy of Sciences and published in the international scientific journal 'Science Advances'.

Researchers analysed data from more than 21,000 river systems worldwide between 1985 and 2023. Using advanced machine learning technology, they tracked long-term changes in dissolved oxygen levels in river water.

The findings show that river oxygen levels have declined by an average of 0.045 milligrams per liter every decade, with nearly 80 per cent of rivers experiencing a downward trend.

Rivers in equatorial regions were found to be the most severely affected. Although earlier assumptions suggested these rivers would face comparatively lower impacts, the study found they were already oxygen-deficient and are now losing oxygen at an even faster rate due to warming temperatures. Researchers say this raises the risk of dangerous low-oxygen conditions for aquatic life.

According to the study, around 63 per cent of the oxygen loss is linked to warmer water holding less dissolved oxygen. Changes in river ecosystems account for another 12 percent, while heatwaves contribute roughly 23 percent of the decline.

The researchers warned that the continuing loss of oxygen in rivers could become a major threat not only to freshwater species but also to global biodiversity and ecological balance.