Between Flood and Drought: The Metric That Could Better Explain What Happens to Water in the Age of Climate Change

“How much rain fell?” is a key question in any discussion about climate. But perhaps there is an even more important one. Like any household budget, the global water economy is based on “income,” that is, water entering the system as precipitation, and “expenditure” – water leaving the system through various forms of evaporation. On land, water evaporates mainly through vegetation, in a process known as evapo-transpiration.