River Deoxygenation: Nearly 800 Warming Rivers are Losing More Oxygen Faster Than Oceans [Study]

Deoxygenation has been a growing ecological and environmental problem in recent years, with most studies focusing on its impact on Earth's oceans in the context of global warming caused by climate change. Since the global ocean is a great emitter of oxygen, this body of water has already lost significant amounts of the said chemical element. In recent years, climate scientists have blamed human-induced global warming for causing the current ocean deoxygenation.

Now, a new study led by researchers from the United States found that nearly 800 rivers are warming rapidly and are losing oxygen faster than oceans. With this, river deoxygenation also threatens marine life, especially animals and plants in freshwater marine habitats. Previous research attributes anthropogenic greenhouse gas emissions and fossil fuel burning to the warming of the world's bodies of water.

River Deoxygenation

(Photo : Photo by Jeremy Bishop on Unsplash)

In the study published in the journal Nature Climate Change on September 14, an international team of researchers led by the University of Pennsylvania discovered the widespread deoxygenation in warming rivers. The research team highlighted that the deoxygenation phenomenon is commonly observed in oceans and lakes but is less expected in shallow waters like flowing rivers.

In particular, the team reconstructed daily water temperature and dissolved oxygen from nearly 800 rivers, including 580 across the U.S. and 216 in Central Europe. This data is made possible by training a deep learning model with temporal weather, water quality data, and static watershed attributes like: hydro-climate, topography, land use, and soil, according to the study.

Based on their results, the team showed that 87% of the rivers showed persistent warming, while 70% of the rivers exhibited deoxygenation. Geography and proximity with human settlements are also factors, since urban rivers showed the most rapid warming, while agricultural rivers incurred the slowest warming but fastest deoxygenation.

Also Read: World's Oceans May be Suffocating Due to Climate Change

Ocean Deoxygenation

As mentioned earlier, oceans and lakes are more often as a subject of focus when it comes to deoxygenation.

According to the International Union for Conservation of Nature (IUCN), the oxygen content of the world's ocean has decreased by 2% since the middle of the 20^th century, predicting that ocean oxygen levels may fall on average by 3% to 4% by the year 2100. This can be possible if the current state of the climate crisis and increased nutrient discharges continue.

The IUCN also notes that the ecological repercussions of ocean oxygen decline include decreased biodiversity, species distribution alterations, algal bloom expansion, and displacement or reduction in fishery resources. In addition, other studies have also shown that the global marine food web could be disrupted as the natural prey of some predators could migrate from their original habitats.

Regardless of which body of water it occurs, deoxygenation will certainly lead to the widespread death of marine organisms. Going back to the Nature Climate Change study, its authors project in the next 70 years, river systems, particularly in the South U.S., are likely to suffer from low oxygen levels that rivers could cause acute death for some fish species and other aquatic life.