Climate change and global water resources: SRES emissions and socio-economic scenarios

摘要: Abstract In 1995, nearly 1400 million people lived in water-stressed watersheds (runoff less than 1000 m 3 /capita/year), mostly south west Asia, the Middle East and around Mediterranean. This paper describes an assessment of relative effect climate change population growth on future global regional water resources stresses, using SRES socio-economic scenarios projections made six models driven by emissions scenarios. River runoff was simulated at a spatial resolution 0.5×0.5° under current climates macro-scale hydrological model, aggregated to watershed scale estimate resource availability for 1300 small islands projections. The A2 storyline has largest population, followed B2, then A1 B1 (which have same population). absence change, depends scenario 2025 ranges from 2.9 3.3 billion (36–40% world's By 2055 5.6 would live future, “only” 3.4 A1/B1. Climate increases stresses some parts world where decreases, including Mediterranean, Europe, central southern America, Africa. other world—particularly eastern Asia—climate runoff, but this may not be very beneficial practice because tend come during wet season extra available dry season. broad geographic pattern is consistent between models, although there are differences magnitude direction Asia. 2020s little clear difference impact or scenarios, large different models: 374 1661 projected experience increase stress. 2050s still assumptions effect. Under 1092 2761 stress; B2 range 670–1538 million, respectively. estimates due slightly patterns models. Sensitivity analysis showed that 10% variation totals could lead variations numbers with decrease stress 15% 20%. these changes actual will depend how managed future.