Rivers at risk: Climate change is diminishing global water quality

Climate change and extreme weather events are damaging water quality in rivers worldwide, according to a comprehensive review of almost 1,000 studies. The scale of the problem, and the urgent need for better water management strategies, are matters that can no longer be ignored.

An international team of researchers, including experts from the University of Adelaide, analyzed 965 studies that were conducted over a span of 22 years from 2000 to 2022. 

Ecological impacts 

One of the most alarming findings was that climate change had increased water temperatures and algae levels in 56 percent of studies. 

This phenomenon is contributing to a decline in dissolved oxygen concentrations in river water. Algae, particularly at excessive levels, can consume vast amounts of oxygen. This deprives other aquatic life and affecting the ecosystem’s balance.

Climate change

The analysis also revealed that droughts and heatwaves led to increased salinity and higher concentrations of pollutants, such as pharmaceuticals.

“The severe effects climate change is already having on water quality globally are very concerning. Previous climate change predictions flagged this, but unfortunately, we are now seeing these extreme events play out across the world,” said study co-author Professor Luke Mosley.

“Rivers are intrinsically important ecosystems but also provide key water sources for drinking water and agriculture. Poor quality water can result in the river water being unsuitable for these uses.”

Poor water quality

Some of the studies in Australia, led by Professor Mosley during the Millennium Drought spanning 2007 to 2020, revealed that water bodies like the River Murray and Lower Lakes experienced shockingly low water levels. These rivers also had poor water quality, notably extreme salinisation and acidification. 

The extreme ecological impacts, such as the tragic Lower Darling River fish kills in 2019, were direct outcomes of deteriorated water quality.

Gaps in our knowledge 

But while the study offers extensive insights, it also highlights gaps in our knowledge. Dr. Michelle van Vliet of Utrecht University, who led the research, wants to see more data on water quality collected in non-Western countries to improve our understanding of the implications of climate change on water quality.

“Most water quality studies now focus on rivers and streams in North America and Europe. We need a better monitoring of water quality in Africa and Asia,” said Dr. van Vliet.

Complex factors

Furthermore, it is not just climate change that’s impacting our rivers. Land use, human activities like wastewater treatment, and other anthropogenic factors are contributing to the damage in our waterways. 

“Understanding the complex interplay between climate, land use and human drivers, which together influence the sources and transport of pollutants is crucial,” said Dr. van Vliet.

Water management systems 

The study, published in the journal Nature Reviews Earth and Environment, paints a bleak portrait of climate change’s effects on global waterways, but there is hope. 

Professor Mosley believes that the research will act as a catalyst for the development of innovative water management systems. 

“Our findings stress the need to improve understanding of the complex hydroclimatic–geographic–human driver feedbacks and to develop technologies and water quality frameworks that support the design of robust water quality management strategies under increasing hydroclimatic extremes,” Professor Mosley said.

“It is hoped this research will spur increasing additional effort and collaboration globally to understand extreme water quality effects.”

“Governments and other policy makers should take note of the findings and consider contingency plans and strategies to try to minimize water quality risks.”

Weather extremes

The results of the study highlight an urgent need for a better understanding of water quality changes during extreme weather events, and the mechanisms underlying this. 

“Only then will we be able to develop effective water management strategies that can safeguard our access to clean water and ensure ecosystem health under climate change and increasing weather extremes,” said Dr. van Vliet.

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