The social-ecological dimensions of changing global freshwater availability

Abstract

Quantifying physical water security at the global scale remains hampered by a lack of systematically produced observational data. Here we combine the observed trends in global freshwater availability from the recently completed Gravity Recovery and Climate Experiment satellite mission1 with more than a dozen other global datasets and provide the missing observational basis to numerous existing perceptions of global water security. We find the disparity between the water ‘haves’ and ‘have nots’ of the world continues to widen2. Nearly one in two people who live in areas of extreme water shortage experienced drying over the 14-year observation period while a fifth of crop calories produced for human food are grown in regions that dried yet already suffer from water shortage. The global water availability trends reveal a clear human imprint1 and reflect a world-wide inability to manage water resources for long term water security. We identify 21 regions that stand to face especially high social-ecological system pressures from the water availability trends and assess flooding and water scarcity vulnerability at the global scale. This application of remotely sensed water availability trends contributes to the quantitative diagnosis of the world’s contemporary water security challenges that will be useful in global policy directive setting.