T. Kahil

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

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 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.

A continental-scale hydro-economic model for integrating water-energy-land nexus solutions

This study presents the development of a new bottom‐up large‐scale hydro‐economic model, Extended Continental‐scale Hydro‐economic Optimization (ECHO), that works at a sub‐basin scale over a continent. The strength of ECHO stems from the integration of a detailed representation of local hydrological and technological constraints with regional and global policies, while accounting for the feedbacks between water, energy and agricultural sectors. In this study, ECHO has been applied over Africa as a case study with the aim of demonstrating the benefits of this integrated hydro‐economic modeling framework. Results of this framework are overall consistent with previous findings evaluating the cost of water supply and adaptation to global changes in Africa. Moreover, results provide critical assessments of future investment needs in both supply and demand side water management options, economic implications of contrasting future socio‐economic and climate change scenarios, and the potential tradeoffs among economic and environmental objectives. Overall, this study demonstrates the capacity of ECHO to address challenging research questions examining the sustainability of water supply, and the impacts of water management on energy and food sectors and vice versa. As such, we propose ECHO as useful tool for water‐related scenario analysis and management options evaluation.

Agriculture and climate change: Potential for mitigation in Spain

Agriculture and forestry activities are one of the many sources of greenhouse gas (GHG) emissions, but they are also sources of low-cost opportunities to mitigate these emissions compared to other economic sectors. This paper provides a first estimate of the potential for mitigation in the whole Spanish agriculture. A set of mitigation measures are selected for their cost-effectiveness and abatement potential and an efficient mix of these measures is identified with reference to a social cost of carbon of 40 €/tCO2e. This mix of measures includes adjusting crop fertilization and managing forests for carbon sequestration. Results indicate that by using the efficient mix of mitigation measures the annual abatement potential could reach 10 million tCO2e, which represents 28% of current agricultural emissions in Spain. This potential could further increase if the social cost of carbon rises covering the costs of applying manure to crops. Results indicate also that economic instruments such as input and emission taxes could be only ancillary measures to address mitigation in agriculture. These findings can be used to support the mitigation efforts in Spain and guide policymakers in the design of country-level mitigation strategies.

Global assessment of water challenges under uncertainty in water scarcity projections

Water scarcity, a critical environmental issue worldwide, has primarily been driven by a significant increase in water extractions during the last century. In the coming decades, climate and societal changes are projected to further exacerbate water scarcity in many regions worldwide. Today, a major issue for the ongoing policy debate is to identify interventions able to address water scarcity challenges in the presence of large uncertainties. Here, we take a probabilistic approach to assess global water scarcity projections following feasible combinations of shared socioeconomic pathways and representative concentration pathways for the first half of the twenty-first century. We identify—alongside trends in median water scarcity—changes in the uncertainty range of anticipated water scarcity conditions. Our results show that median water scarcity and the associated range of uncertainty are generally increasing worldwide, including many major river basins. On the basis of these results, we develop a general decision-making framework to enhance policymaking by identifying four representative clusters of specific water policy challenges and needs.Designing interventions to address water scarcity under climate change is challenging given the large uncertainties in projected water availability. In this study, changes in the uncertainty range of anticipated water scarcity conditions are identified, and a general decision-making framework to support policy decisions is developed.