Water cooperation to cope with twenty-first century challenges

The twenty-first century, referred to as the Anthropocene, will leave us with tremendous environmental changes. Unprecedented population growth, a changing climate, rapid urbanization, expansion of infrastructure, migration, land conversion and pollution translate into changes in the fluxes, pathways and stores of water—from rapidly melting glaciers to the decline of groundwater due to overexploitation. Population density and per capita resource use have increased dramatically over the past century, and watersheds, aquifers and the associated ecosystems have undergone significant modifications that affect the vitality, quality and availability of the resource. Current United Nations predictions estimate that the world population will reach 9 billion in 2050. The exponential growth in population and the more intensive use of water per capita are among the leading key drivers behind hydrologic change and its impact. It is a huge challenge on an already resource-limited planet to meet the various needs of the people, especially of those who already lack access to clean water.1 The variability, vulnerability and uncertainty of global water resources will be further exacerbated by increasingly erratic weather events, including droughts, floods and storms. Such disasters seriously impede efforts to meet the Millennium Development Goals. Water scarcity due to drought, land degradation and desertification already affects 1.5 billion people in the world and is closely associated with poverty, food insecurity and malnutrition.