New research finds Earth's rivers are warming even faster than its oceans, and could eventually be so hot and oxygen-deprived that certain fish start to die off.
A study published in Nature Climate Change this week found that in nearly 800 rivers across the world, 87% had warmed and 70% had lowered oxygen levels. The findings suggest that within a century, oxygen levels in some rivers will have dropped so low in certain regions that some fish won't be able to survive there.
The study analyzed data from 580 rivers in the U.S. and 216 in Europe. Urban rivers were warming fastest, according to the new data, and rural rivers were losing their oxygen at the fastest rate.
It's another sign of the global effects of climate change, researchers say.
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"We know that a warming climate has led to warming and oxygen loss in oceans, but did not expect this to happen in flowing, shallow rivers," said Li Li, Penn State’s Isett professor of civil and environmental engineering and corresponding author on the paper. "This is the first study to take a comprehensive look at temperature change and deoxygenation rates in rivers — and what we found has significant implications for water quality and the health of aquatic ecosystems worldwide."
Researchers say the death of fish could weaken and threaten the larger environments that depend on riverine ecosystems.
