
Earth’s Hidden Mantle Water May Outsize All Surface Freshwater
A diamond-hosted ringwoodite inclusion proves water is chemically bound in Earth's mantle transition zone (410–660 km deep). If representative, this hydrated zone could hold multiple times the volume of Earth’s surface oceans, making mantle water a vast, long-term reservoir that participates in the deep water cycle. The water is not liquid at surface conditions and isn’t recoverable on human timescales, but its existence reshapes our understanding of Earth's total water budget and how surface oceans are buffered over geological time.












