EAPS Department Lecture Series - Tom Gleeson, University of Victoria

"How much groundwater is on earth? The first global assessment of the volume and distribution of modern groundwater" | EAPS Department Lecture Series | Refreshments, 3:30 pm, Ida Green Lounge | More info: For the first time since a back-of-the-envelope calculation of the global volume of groundwater was attempted in the 1970s, we produced the first data-driven estimate of the Earth's total supply of groundwater and showed that less than six per cent of groundwater in the upper two kilometres of the Earth's landmass is renewable within a human lifetime. Using multiple datasets (including data from close to a million watersheds), and more than 40,000 groundwater models, we estimated a total volume of nearly 23 million cubic kilometres of total groundwater of which 0.35 million cubic kilometres is younger than 50 years old. Why is it important to differentiate old from modern groundwater? Young and old groundwater are fundamentally different in how they interact with the rest of the water and climate cycles. The volume of modern groundwater dwarfs all other components of the active water cycle and may be a more renewable resource but it's also more vulnerable to climate change and contamination by human activities.

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