Seite - 15 - in options, Band summer 2018

15 summer 2018 ◼ optionswww.iiasa.ac.at Asia is currently home to 4.5 billion people, who use around 65% of the world’s water supply. Around 30% of the Asian population is already facing water scarcity. India and China have experienced close to double-digit GDP growth in recent years, as well as a population boom. Many river basins already cannot cope with the demands placed upon them. As the effects of climate change really become visible and a continued improvement of socioeconomic conditions cause population numbers to rise still further–with wealthier societies on average requiring more water anyway–what will happen to water supply and demand? Will the problems be worse in some areas than in others? What will exacerbate the situation? Can the problem be reduced? These are just some of the issues faced by policymakers in Asia today. IIASA Water Program researchers are coming to their aid using multiple hydrological models together with the latest global climate change and socioeconomic scenarios. Yusuke Satoh and a team of other IIASA researchers were tasked by the Asian Development Bank to evaluate the risks and find out which areas of the continent might be most vulnerable. Understanding potential risks are vital to developing management and adaptation strategies. Although there are studies on future water scarcity under climate change, they are all missing something essential. “Most existing studies discuss the impact of climate change on water scarcity, but because there were no water use scenarios, they couldn’t assess the impact of changing water demand,” says Satoh. This is groundbreaking work undertaken by the Water Futures and Solutions (WFaS) initiative as part of the IIASA Water Program. New scenarios WFaS was set up six years ago by IIASA, with partners including UNESCO, the International Water Association, and the World Water Council, to look at sustainable solutions to local, national, and global water challenges. It aims to include a wide range of stakeholders, rather than just scientific researchers. “The biggest feature of WFaS, I think, is stakeholder engagement,” says Satoh. ”In order to include as many potential futures as possible we need more, broader perspectives, and we need stakeholder opinions.” One of the major achievements of WFaS has been to develop water use scenarios. The scenarios were developed at a WFaS stakeholder meeting and were based on the five existing Shared Socioeconomic Pathways (SSPs) and the four Representative Concentration Pathways (RCPs). The SSP scenarios were originally developed by IIASA researchers to suggest different ways in which the world and society could progress, depending on decisions made by policymakers and society, while the RCPs are the four greenhouse gas concentration trajectories used by the Intergovernmental Panel on Climate Change in compiling its Fifth Assessment Report. IIASA was also involved in the development of the RCPs. “The SSP and RCP scenarios do not include information on water use, because their interest is emissions,” explains Satoh. “What we did, is develop water use scenarios to make projections for water security.” Each scenario is a combination of an SSP and an RCP. “For each combination of SSP and RCP, we assumed water use change according to socioeconomic change. In SSP1, society will