Climate Change and Threats to Water Security: A Review

An overview of publications on the hydrological consequences of climate change in the context of the ongoing and projected threats to water security is presented. Two hydrological indicators of water security are considered both at the global and regional scales: mean river flow regime as an indicator of the provision of the territory with surface water resources, as well as the flood regime, as an indicator of flood hazard. The paper is structured as follows. The first section briefly discusses the current understanding of the mechanisms of the influence of anthropogenic climate change on water resources and flood hazard. The second section considers the methodological aspects of constructing assessments of the ongoing changes in the river regimes, and reviews some of the estimates of changes in water resources and high river flow in the world and Russia. The third section is devoted to the global and regional assessments of future changes in the river runoff regime in the twenty-first century and discusses the methodological challenges of carrying out such assessments. The fourth section evaluates socio-economic consequences of the current and forecasted hydrological changes and their influence on water security. The paper is finalized by several summarizing remarks.