A global water scarcity assessment under Shared Socio-economic Pathways – Part 1: Water use

摘要

A novel global water scarcity assessment for the 21st century ispresented in a two-part paper. In this first paper, water use scenarios arepresented for the latest global hydrological models. The scenarios arecompatible with the socio-economic scenarios of the Shared Socio-economicPathways (SSPs), which are a part of the latest set of scenarios on globalchange developed by the integrated assessment, the IAV (climate changeimpact, adaptation, and vulnerability assessment), and the climate modelingcommunity. The SSPs depict five global situations based on substantiallydifferent socio-economic conditions during the 21st century. Water usescenarios were developed to reflect not only quantitative socio-economicfactors, such as population and electricity production, but also keyqualitative concepts such as the degree of technological change and overallenvironmental consciousness. Each scenario consists of five factors:irrigated area, crop intensity, irrigation efficiency, and withdrawal-basedpotential industrial and municipal water demands. The first three factorsare used to estimate the potential irrigation water demand. All factors weredeveloped using simple models based on a literature review and analysis ofhistorical records. The factors are grid-based at a spatial resolution of0.5° × 0.5° and cover the whole 21stcentury in five-year intervals. Each factor shows wide variation among thedifferent global situations depicted: the irrigated area in 2085 variesbetween 2.7 × 106 and 4.5 × 106 km2,withdrawal-based potential industrial water demand between 246 and 1714 km3 yr?1,and municipal water between 573 and 1280 km3 yr?1. The water usescenarios can be used for global water scarcityassessments that identify the regions vulnerable to water scarcity andanalyze the timing and magnitude of scarcity conditions.