Ancient underworld waters fuel Earth’s hidden microbial empire
Scientists mapped a global network of hydrogen-rich waters trapped deep in Precambrian shield rocks and identified two reactions— radiolytic breakdown of water and serpentinization—that generate hydrogen, providing a long-lasting energy source for microbes isolated from the surface. Studied across 19 mines in Canada, South Africa, and Scandinavia, the hydrogen output may rival marine systems, suggesting a vast, enduring subsurface biosphere and reshaping ideas about Earth's habitable volume and the search for life on Mars.