PARIS, Sept 19 — In the USA and Europe, rivers are warming faster than the oceans, report US researchers who examined almost 800 rivers in these two regions of the world.

According to their findings, warming had occurred in 87 per cent of the rivers studied, and oxygen loss had occurred in 70 per cent, with potentially serious repercussions for aquatic life, as well as for local residents.

Climate change is having a definite impact on the health of the planet’s aquatic ecosystems: some lakes are changing colour, while oceans are acidifying.

Moreover, rivers are warming and losing oxygen, according to the findings of a study recently published in the journal, Nature Climate Change.

Carried out by researchers at Pennsylvania State University, the research is based on artificial intelligence and deep learning models, which the scientists used to reconstruct historically sparse water quality data for almost 800 rivers (580 in the USA and 216 in Central Europe).

From annual precipitation rates to soil type and sunlight, numerous criteria were taken into account to assess the quality of these waterways.

In analysing them, the authors found that rivers are warming and deoxygenating faster than oceans.

According to the study, 87 per cent of rivers have warmed over the past four decades, and 70 per cent of them have lost oxygen. Urban rivers have been the most affected by warming, while agricultural rivers have experienced the slowest warming but the fastest deoxygenation.

The researchers also state that, for all the rivers studied, future deoxygenation rates are forecast to be between 1.6 and 2.5 times higher than historical rates.

And that’s not all: over the next 70 years, river systems (particularly those in the southern USA) are likely to experience periods when oxygen levels are so low that rivers could “induce acute death” for certain fish species, threatening aquatic diversity as a whole.

“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, quoted in a news release.

“Rivers are essential for the survival of many species, including our own, but they have historically been overlooked as a mechanism for understanding our changing climate.

This is our first real look at how rivers throughout the world are faring — and it’s disturbing.” — ETX Studio