Dry land isn’t really dry. It’s saturated with truly vast volumes of groundwater, hidden in the spaces of the earth we walk on. How much? Recent estimates put it at almost two trillion Olympic swimming pools of water stored in the upper 10 km of continental crust.
Groundwater has been hugely beneficial to us for use in agriculture or as drinking water. As the world warms and waterways dry up, this extraction will only increase. But there’s a hidden problem. We used to think the organic matter in groundwater didn’t react when brought up. Sadly, the reverse is true. Our new research published in Nature Communications has found when groundwater – especially from deep down – is pumped to the surface, it brings with it dissolved organic matter preserved from long ago. Once sunlight and oxygen hit this matter, it can easily turn into carbon dioxide.