The impact of climate change policy on the risk of water stress in southern and eastern Asia

Abstract

The adequacy of freshwater resources remains a critical challenge for a sustainable and growing society. We present a self-consistent risk-based assessment of water availability and use under future climate change and socioeconomic growth by midcentury across southern and eastern Asia (SEA). We employ large ensemble scenarios from an integrated modeling framework that are consistent across the spectrum of regional climate, population, and economic projections. We find socioeconomic growth contributes to an increase in water stress across the entire ensemble. However, climate change drives the ensemble central tendency toward an increase in water stress in China but a reduction in India, with a considerable spread across the ensemble. Nevertheless, the most deleterious unabated climate-change impact is a low probability but salient extreme increase in water stress over China and India. In these outcomes, annual withdrawals will routinely exceed water-storage capacity. A modest greenhouse gas mitigation pathway eliminates the likelihood of these extreme outcomes and also benefits hundreds of millions of people at risk to various levels of water stress increase. Over SEA we estimate an additional 200 million people under threat of facing at least heavily water-stressed conditions from climate change and socioeconomic growth, but the mitigation scenario reduces the additional population-under-threat by 30% (60 million). Nevertheless, there remains a 1-in-2 chance that 100 million people across SEA experience a 50% increase in water stress and a 1-in-10 chance they experience a doubling of water stress. Therefore, widespread adaptive measures may be required over the coming decades to meet these unavoidable risks in water shortfalls.

A Spatially Explicit Assessment of Growing Water Stress in China From the Past to the Future

“…Various indicators have been proposed which indicate the level of water demand relative to water availability at a place during a specific period of time (Smakhtin et al, 2004). Toward the future, increasing water stress is projected for many regions (including China) of the world due to population growth, socioeconomic development and climate change (Gao et al, 2018;Greve et al, 2018;Schewe et al, 2014;Vörösmarty et al, 2005). Toward the future, increasing water stress is projected for many regions (including China) of the world due to population growth, socioeconomic development and climate change (Gao et al, 2018;Greve et al, 2018;Schewe et al, 2014;Vörösmarty et al, 2005).…”

“…With a growing population and rapid economic development, many areas of China have been experiencing severe water stress for recent decades Wang et al, 2016). Water stress in China has been assessed in previous studies at different geographical scales, ranging from provincial level (Cai et al, 2017;Zhao et al, 2015), large river basin level (Gao et al, 2018), to small catchment level (Wang et al, 2016). Water stress in China has been assessed in previous studies at different geographical scales, ranging from provincial level (Cai et al, 2017;Zhao et al, 2015), large river basin level (Gao et al, 2018), to small catchment level (Wang et al, 2016).…”

“…Many regions of the world have suffered water stress to different extents (Oki & Kanae, 2006;. Toward the future, increasing water stress is projected for many regions (including China) of the world due to population growth, socioeconomic development and climate change (Gao et al, 2018;Greve et al, 2018;Schewe et al, 2014;Vörösmarty et al, 2005). Understanding the nature of water stress can assist in developing effective water resources management strategies associated with regional development within the context of global change.…”

“…Severe water stress may cause various environmental and social issues, such as reduction of crop production and degraded water quality that threatens human health (Cheng et al, 2009). Water stress in China has been assessed in previous studies at different geographical scales, ranging from provincial level (Cai et al, 2017;Zhao et al, 2015), large river basin level (Gao et al, 2018), to small catchment level (Wang et al, 2016). These assessments demonstrated the general regional feature of water stress and helped understand water stress at relatively large scales in China.…”

City water stress and industrial water-saving potential in stringent management of China

“…Although nation-wide China is deficient in water 11 , with a wicked problem between water demand and availability 4,12 , city-level water scarcity has not been fully explored 13 . The science of water scarcity assessment has developed for the past 30 years and, as more spatial geo-data have been available, studies have adopted more integrated and multi-faceted approaches typically based on spatial resolution in grid units at the river basin scale 14,15 or global levels [16][17][18] , rather than at administrative/territory based units such as the city level. There is only a single city-level based study in 2005 from the Ministry of Water Resources in China, which is not widely available to the public 19 .…”