A new study has revealed that rising global temperatures could render groundwater toxic for nearly 590 million people by the end of the century, highlighting a significant but often overlooked consequence of climate change.
Without easy access to freshwater lakes, streams, and dams, approximately one in four people globally depend on groundwater for survival. As surface water sources become increasingly scarce, reliance on groundwater is expected to grow. However, the study published in Nature Geoscience warns that this critical resource is under severe threat from global warming.
An international team of researchers developed a global-scale model of heat transport to quantify temperature changes in groundwater sources worldwide under various warming scenarios. The findings are alarming: under the worst-case scenario, nearly 590 million people could be relying on groundwater that fails to meet the strictest standards for potable water by 2100.
“A lot of focus on climate change has rightfully been to do with weather events and the availability of water,” explained Dylan Irvine, a hydrologist from Charles Darwin University in Australia. “But we do need to think more broadly about the impact that climate change will have on groundwater.”
The study’s lead author, Susanne Benz from the Karlsruhe Institute of Technology in Germany, added, “There are already about 30 million people living in regions where the groundwater is warmer than stipulated in the strictest drinking water guidelines.”
Warming groundwater by just a degree or two can have catastrophic results, including reduced oxygen levels, the growth of dangerous bacteria, and increased concentrations of heavy metals like arsenic and manganese. These changes could make water unsafe to drink without significant treatment.
In a moderate scenario where current trends continue, 77 to 188 million people could be affected by unsafe groundwater by 2100. However, in an extreme scenario of escalating carbon emissions, up to 588 million people could require extensive water treatment to make groundwater safe for consumption.
Not all regions will face equal risks. Areas with deep water tables, such as the Andes and Rocky Mountains, may remain safe longer. In contrast, regions with shallow water systems and high rates of atmospheric warming are likely to face more significant challenges, often lacking the resources needed to ensure water safety.
The research team has developed an interactive Google Earth Engine application allowing users to explore projected changes in groundwater temperatures in their areas. “Our results show how important it is to take action to protect groundwater and find lasting solutions to counteract the negative impact of climate change on groundwater,” emphasized Benz. (With inputs from sciencealert.com)