Water as a Non-infinite Resource: Human Appropriation, Water Footprint, and Water Scarcity

Fresh water is a fundamental resource for humankind. However, renewable freshwaters constitute only 0.33% of the total earth water. Here will be presented an assessment of blue and green waters spatially and temporally available, the analysis of anthropic appropriation of these resources and a brief overview of future trends in a business-as-usual scenario. Estimates on spatially and temporally available global blue water flows range from 12,000 to 16,300 km3/year. The current anthropic withdrawal estimate of blue water is 6900 km3/year, consumption is 3400 km3/year, being 55 and 27% of the available flows, respectively. Both common sense and environmental indicators like the planetary boundary for consumptive freshwater use (1100–4500 km3/year), point out that current freshwater exploitation is not sustainable. There is an urgent need to implement new practices to decrease of water footprint, especially in food production. These practices must shift the use of freshwater resources from the paradigm of the cowboy economy, i.e. the negligibility of exploited resources, to the spaceship model (recycling and reuse).