Global threats to human water security and river biodiversity

Protecting the world’s freshwater resources requires diagnosing threats over a broad range of scales, from global to local. Here we present the first worldwide synthesis to jointly consider human and biodiversity perspectives on water security using a spatial framework that quantifies multiple stressors and accounts for downstream impacts. We find that nearly 80% of the world’s population is exposed to high levels of threat to water security. Massive investment in water technology enables rich nations to offset high stressor levels without remedying their underlying causes, whereas less wealthy nations remain vulnerable. A similar lack of precautionary investment jeopardizes biodiversity, with habitats associated with 65% of continental discharge classified as moderately to highly threatened. The cumulative threat framework offers a tool for prioritizing policy and management responses to this crisis, and underscores the necessity of limiting threats at their source instead of through costly remediation of symptoms in order to assure global water security for both humans and freshwater biodiversity. Dual threat to river biodiversity and water security Access to fresh water is essential for all life forms, but water security for humans and biodiversity are often seen as competing priorities. A new analysis of the threats to the world's rivers breaks new ground by accounting for a broad array of stressors and their downstream effects, from both human and biodiversity perspectives. A subsequent analysis of investments in water resources offers insights into the sources of global disparities in human water security that separate rich from poor. The authors conclude that rivers are in a state of crisis, and that nearly 80% of humanity lives in areas where threat levels are relatively high. River-dwelling species face similarly great challenges around the world. Achieving a sustainable solution to these problems, the authors say, will require creative solutions that jointly address water security for humans and biodiversity, and that treat underlying causes rather than merely symptoms. Water security affects human wellbeing both directly and indirectly, through its effects on biodiversity. Here, a global map has been generated that shows threats to both direct and indirect water security from a full range of potential stressors. Technological investments have also been incorporated. The map shows that nearly 80% of the world's population is exposed to high level