Without easy access to freshwater lakes, streams, and dams, roughly one out of every four humans depends on reservoirs beneath Earth’s surface for survival. By the end of the century, tens to hundreds of millions could be deprived of even this tenuous supply of moisture as rising temperatures risk turning shallow groundwater supplies into toxic sumps.
GROUNDWATER UNDER THREAT
An international team of researchers has developed a global-scale model of heat transport to quantify the temperature changes of groundwater sources around the world under various warming scenarios. In the worst case, nearly 590 million people in 2100 could be reliant on water sources that don’t meet the strictest standards for potable water.
Hydrologist Dylan Irvine from Charles Darwin University in Australia explains, “A lot of focus on climate change has rightfully been to do with weather events and the availability of water. But we do need to think more broadly about the impact that climate change will have on groundwater.”
HIDDEN IMPACT OF WARMING GROUNDWATER
Water trapped within porous rocks just below the surface can be full of dissolved minerals, pollutants, and potential pathogens, often making it a desperate last resort for communities reliant upon it. Warm these slow-moving reservoirs by just a degree or two, and the results can be catastrophic, robbing the environment of oxygen, facilitating the growth of dangerous bacteria, or dissolving excessive concentrations of heavy metals like arsenic or manganese.
Geoscientist Susanne Benz from the Karlsruhe Institute of Technology in Germany, and lead author of the study, highlights that “There are already about 30 million people living in regions where the groundwater is warmer than stipulated in the strictest drinking water guidelines. That means it may not be safe to drink the water there without treatment. It may need to be boiled first, for example. The drinking water also gets warmed up in water pipes by heat in the ground.”
PROJECTED IMPACTS AND REGIONAL DISPARITIES
Even for populations with sufficiently-sized surface reservoirs nearby, discharges of heated groundwater could alter key dynamics that keep its water safe for human consumption. Under a business-as-usual ‘shared socioeconomic pathway’ where little changes, current figures could more than double, with 77 to 188 million people projected to live in areas where groundwater fails to meet the strictest standards for drinkability by 2100. In an extreme case of escalating carbon emissions, up to 588 million individuals could require significant water treatment before consumption.
Not all locations will be at equal risk. Regions with deep water tables, such as the Andes and Rocky Mountains, could remain safe as waters stay cooler for far longer. Conversely, communities in areas with shallow water systems or exceedingly high rates of atmospheric warming will almost certainly need to cope with groundwater temperatures rising to concerning levels. In many cases, these are also the communities with the fewest resources available for making their water safe.
A CALL FOR ACTION
The team has developed an interactive Google Earth Engine application to allow anyone to explore the projected changes in their area. “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,” says Benz.
SOLUTIONS FOR SUSTAINABLE GROUNDWATER MANAGEMENT
- Investing in Renewable Energy Shifting towards renewable energy sources can significantly reduce carbon emissions, helping to mitigate global warming and its impact on groundwater temperatures.
- Implementing Advanced Water Treatment Technologies Developing and deploying advanced water treatment technologies can help ensure that groundwater remains safe for consumption, even as temperatures rise.
- Enhancing Groundwater Monitoring and Management Improved monitoring of groundwater temperatures and quality can help in early detection of potential issues, allowing for timely interventions to protect water supplies.
- Promoting Sustainable Water Use Practices Encouraging sustainable water use practices, including efficient irrigation techniques and water-saving technologies, can reduce the strain on groundwater resources.
- Fostering International Cooperation Global collaboration is crucial for sharing knowledge, technologies, and resources to address the challenges posed by climate change to groundwater supplies.
