Future long-term changes in global water resources driven by socio-economic and climatic changes

Abstract

A global water model is used to analyse the impacts of climate change and socio-economic driving forces (derived from the A2 and B2 scenarios of IPCC) on future global water stress. This work extends previous global water research by analysing not only the impact of climate change and population, but also the effects of income, electricity production, water-use efficiency and other driving forces, on water stress. Depending on the scenario and climate model, water stress increases (between current conditions and the 2050s) over 62.0-75.8% of total river basin area and decreases over 19.7-29.0% of this area. The remaining areas have small changes. The principal cause of decreasing water stress (where it occurs) is the greater availability of water due to increased annual precipitation related to climate change. The principal cause of increasing water stress is growing water withdrawals, and the most important factor for this increase is the growth of domestic water use stimulated by income growth. (Population growth was a much less important factor and irrigated area was assumed to remain constant.) To address the uncertainty of water stress estimates, three different indicators of water stress were computed and compared. The overlap area of their computation of "severe stress" in the 2050s was large (approximately 23 10 6 km 2 or 56-73 % of the total "severe stress" area). This indicates a moderate level of agreement and robustness in estimates of future water stress. At the same time the indicators disagreed in many other areas, suggesting that work is still needed to elaborate general indicators and concepts of water stress.Key words global water resources; global change; water scenarios; water availability; water stress; climate change and water Changements futurs à long terme dans les ressources en eau globales forcés par les changements climatiques et socio-économiquesRésumé Un modèle hydrologique global est utilisé pour analyser les impacts du changement climatique et des forçages socio-économiques (déduits des scénarios A2 et B2 de l'IPCC) sur le stress hydrique global futur. Ce travail étend les recherches hydrologiques globales précédentes en analysant non seulement l'impact du changement climatique et de la population, mais aussi les effets des intrants, de la production électrique, de l'efficience des usages de l'eau et d'autres forçages sur le stress hydrique. Selon le scénario et le modèle climatique, le stress hydrique augmente (entre les conditions actuelles et les années 2050) sur 62.0-75.8% de l'aire totale des bassins hydrographiques et diminue sur 19.7-29.0% de cette aire. L'aire restante présente de faibles changements. La cause principale de la décroissance du stress hydrique (là où elle survient) est la plus grande disponibilité de l'eau due à l'augmentation de la précipitation annuelle en relation avec le changement climatique. La cause principale de l'augmentation du stress hydrique est l'augmentation des prélèvements d'eau, dont le facteur le plus important est la croissance des...

Water security, global change and land–atmosphere feedbacks

“…(c) Anthropogenic interventions in the water cycle While physical science can provide important information on the availability of water in the future, the role of changing anthropogenic intervention is often as critical in developing scenarios of change in freshwater systems [29,30]. Anthropogenic interventions that form part of natural resource management include the regulation of river flows using dams, artificial abstraction from surface or groundwater stores and the use of water from a range of sources for irrigation.…”

Water availability in +2°C and +4°C worlds

“…A large number of studies have assessed the impact of climate change on global water resources and have been reported in the series of assessment reports conducted by the Intergovernmental Panel on Climate Change (IPCC) [4] and in a number of other publications [5][6][7][8][9][10][11]. These analyses have typically used ensembles of global climate models (GCMs) developed by a number of modelling centres across the globe, the so-called ensembles of opportunity or multi-model ensembles (MMEs).…”

On the credibility of climate predictions

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