Multi‐model and multi‐scenario assessments of Asian water futures: The Water Futures and Solutions (WFaS) initiative

Abstract

This paper presents one of the first quantitative scenario assessments for future water supply and demand in Asia to 2050. The assessment, developed by the Water Futures and Solutions (WFaS) initiative, uses the latest set of global climate change and socioeconomic scenarios and state-of-the-art global hydrological models. In Asia, water demand for irrigation, industry, and households is projected to increase substantially in the coming decades (30-40% by 2050 compared to 2010). These changes are expected to exacerbate water stress, especially in the current hotspots such as north India and Pakistan, and north China. By 2050, 20% of the land area in the Asia-Pacific region, with a population of 1.6-2 billion, is projected to experience severe water stress. We find that socioeconomic changes are the main drivers of worsening water scarcity in Asia, with climate change impacts further increasing the challenge into the 21st century. Moreover, a detailed basin-level analysis of the hydro-economic conditions of 40 Asian basins shows that although the coping capacity of all basins is expected to improve due to gross domestic product (GDP) growth, some basins continuously face severe water challenges. These basins will potentially be home to up to 1.6 billion people by mid-21st century.Plain Language Summary Home to almost 4.5 billion people, Asia has experienced unprecedented economic and population growth in recent decades. In order to sustain growing food demand and increasing standard of living, water use has been increasing rapidly in many parts of Asia. At present, water withdrawals in Asia represent 65% of the global total. This huge abstraction of water resources has resulted in many Asian regions undergoing pervasive water scarcity conditions. The imminent global changes from climate change and socioeconomic development in Asia are expected to place additional pressures on water resources in the coming decades. In such a context, it is imperative to evaluate future water scarcity conditions and identify regions at highest risk in Asia. We found that by 2050, 20% of the land area in Asia, with population exceeding 1.6-2.0 billion, is projected to experience severe water scarcity. Here, we for the first time highlight that socioeconomic changes are the main driver of worsening water scarcity in Asia, much larger than the climate change impacts.

Global exposure and vulnerability to multi-sector development and climate change hotspots

“…Risks are not just dependent on the severity of climate change and subsequent hazards but critically depend on the population's spatial distribution (exposure) and their vulnerability and capacity to prepare for and manage changing risks [5]. Increasingly studies are showing that the world's poorest are disproportionately exposed to changes in temperature extremes [6,7] and challenging hydro-climatic complexity [8][9][10]. In the water sector, between 8%-14% of the global population are expected to face severe reductions in available water resources between 1.7 • C-2.7 • C [11] and in the energy sector, more than 70% of a 'business as usual' 2050s population could expect climate sensitive changes in energy demand of +/− 5%, with negative impacts overwhelmingly in low and middle income countries [12].…”

A Global Analysis of Future Water Deficit Based On Different Allocation Mechanisms

“…A comparison of three different models showed for SSP2 a range of 25–125% increase, with an average of 85% (Wada et al, ), showing that our results are within this range—although on the low side (in an earlier paper, we discussed that the main reason is that we assume a higher efficiency increase; Bijl et al, ). Regional patterns across the models are comparable showing most increase in Africa and Asia (Satoh et al, ; Wada et al, ). In the WaterEff scenario, the socioeconomic drivers from SSP‐2 combined with the efficiencies of SSP‐1 result in a nonagricultural demand increase of 37% during 2010–2050.…”

“…Hanasaki et al () developed a set of integrative scenarios of water use for all sectors based on the Shared Socioeconomic Pathways (SSPs; O'Neill et al, ) and demonstrated that the socioeconomic scenarios and associated water use scenario dominate the impact of the water scarcity in the 21st century. Since then, different integrated model‐based scenarios have been developed to understand the global water use and demand (Parkinson et al, ; Satoh et al, ; Wada et al, ), mostly using the SSP scenarios as their basis focusing on industrial use or, for instance, on coupled climate development impacts (Parkinson et al, ). These studies conclude that socioeconomic changes are the main drivers of water scarcity, for all SSP scenarios.…”

Influence of Groundwater Extraction Costs and Resource Depletion Limits on Simulated Global Nonrenewable Water Withdrawals Over the Twenty‐First Century

“…Continued depletion of finite groundwater reserves raises globally significant threats, including abrupt agricultural decline (Aeschbach-Hertig & Gleeson, 2012) and associated disruption to internationally traded food supplies (Dalin et al, 2017). The problem is likely to worsen as socioeconomic development increases global demands for water (Satoh et al, 2017). Sustainable management of groundwater is thus marked as a major global policy challenge, requiring risk analysis informed by long-range projections of aquifer exploitation and exhaustion across the world's most important basins of irrigated agriculture (Ashraf et al, 2017;Connor, 2015).…”