Groundwater temperatures could rise several notches by 2100, making it too hot to drink for millions!

Groundwater, the Earth's largest source of unfrozen freshwater, is under threat. As our planet heats up, so too does the water hidden beneath our feet. Researchers at Karlsruhe Institute of Technology predict that by 2100, groundwater temperatures could rise significantly, exceeding safe drinking water standards in many regions.

The culprit? Greenhouse gases. Their build-up in the atmosphere traps heat, warming not just the air but also the ground and the water it holds. The study used two climate scenarios, one moderate and one extreme, to estimate the impact. In both cases, the results were concerning.

Under the more moderate scenario, groundwater temperatures are projected to rise by 2.1°C by 2100. This may not seem like much, but it's enough to push millions over the edge. Currently, around 30 million people already live in areas where groundwater exceeds safe drinking limits. With rising temperatures, this number could balloon to 77 to 188 million by 2100.

Extreme scenarios paint an even bleaker picture. Here, groundwater temperatures could soar by 3.5°C, potentially impacting a staggering 59 to 588 million people. The vast range reflects regional variations in climate change and population growth.

The consequences of this hidden warming are far-reaching. Warmer groundwater can harbour harmful substances like arsenic and manganese, threatening human health. It can also disrupt delicate ecosystems and even impact geothermal energy potential. Fish, particularly those that rely on cool groundwater for spawning, could face reproductive issues.

This isn't just an environmental concern; it's a public health crisis in the making. We need to act now to protect our precious groundwater resources. Sustainable practices, coupled with efforts to combat climate change, are crucial to ensure a future where clean drinking water remains a right, not a privilege.

The findings of this study have been detailed in Nature Geoscience and can be accessed here.