Integrated assessment of global water scarcity over the 21st century under multiple climate change mitigation policies

• DOI: 10.5194/hess-18-2859-2014
• Publication Date: 2014-08-06T08:37:10Z
• Authors: M. I. Hejazi; J. Edmonds; L. Clarke; P. Kyle; E. Davies; V. Chaturvedi; M. Wise; P. Patel; J. Eom; K. Calvin
• Keywords: Representative Concentration Pathways; Carbon tax; Baseline (sea)

Abstract. Water scarcity conditions over the 21st century both globally and regionally are assessed in context of climate change mitigation policies, by estimating water availability demand within Global Change Assessment Model (GCAM), a leading community-integrated assessment model energy, agriculture, climate, water. To quantify changes future availability, new gridded water-balance global hydrologic – namely, Availability (GWAM) is developed evaluated. demands for six major sectors (irrigation, livestock, domestic, electricity generation, primary energy production, manufacturing) modeled GCAM at regional scale (14 geopolitical regions, 151 sub-regions) then spatially downscaled to 0.5° × resolution match GWAM. Using baseline scenario (i.e., no policy) with radiative forcing reaching 8.8 W m−2 (equivalent SRES A1Fi emission scenario) three policy scenarios increasing stringency 7.7, 5.5, 4.2 A2, B2, B1 scenarios, respectively), we investigate effects policies on scarcity. Two carbon tax regimes (a universal (UCT) which includes land use emissions, fossil fuel industrial emissions (FFICT) excludes emissions) analyzed. The results more than half world population living under extreme end century. Additionally, years 2050 2095, 36% (28%) 44% (39%) population, respectively, projected live grid cells (in basins) that will experience greater amount available year index (WSI) > 1.0). When comparing while maintaining same socioeconomic assumptions, declines UCT but increases FFICT particularly stringent targets. Under scenario, increase, driven higher bio-energy crops.