Editing IPCC:AR6/WGII/Cross-Chapter-Paper-5 (section)

==== CCP5.3.2.2 KR2: Risks to Livelihoods and the Economy from Changing Water Resources ====

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KR2 encompasses the relative and absolute dependence on water resources for economic activities and livelihood sustainment in mountain regions and in lowlands (Table SMCCP5.19). Particularly affected by changes in water resources will be regions with (seasonally) high dependence on snow and glacier melt, i.e., arid and semiarid zones in the Andes, Central Asia and the Upper Indus Basin ( [[#Huss--2017|Huss et al., 2017]] ; [[#Huss--2018|Huss and Hock, 2018]] ; [[#Viviroli--2020|Viviroli et al., 2020]] ) (Section CCP5.3.1).

Consequences that are considered severe refer to the magnitude (number of people and economic activities affected), timing (increase of water stress as early as mid-century in several regions) and likelihood (severe risk consequences are more ''likely'' where high population density is projected) ( ''high confidence'' ) (Figures CCP5.1 and CCP5.6, Section 4..5.7 and 4.7) ( [[#Fuhrer--2014|Fuhrer et al., 2014]] ; [[#Wijngaard--2018|Wijngaard et al., 2018]] ; [[#Biemans--2019|Biemans et al., 2019]] ; [[#Immerzeel--2020|Immerzeel et al., 2020]] ; [[#Viviroli--2020|Viviroli et al., 2020]] ). Severe consequences are that by mid-century more than half of agricultural regions equipped for irrigation are projected to be dependent on mountain runoff and could therefore be unsustainably using blue water (e.g., water from river, lakes and aquifers) ( [[#Viviroli--2020|Viviroli et al., 2020]] ) or that the number of people being water stressed will increase by 50% to 100% in areas already currently water stressed ( [[#Munia--2020|Munia et al., 2020]] ). Hotspot regions are those with large lowland populations depending on essential mountain water resource contributions and include river catchments such as the Ganges, Brahmaputra, Meghna, Yangtze, Nile, Niger, Indus, Euphrates-Tigris or Pearl ( ''high confidence'' ) ( [[#Viviroli--2020|Viviroli et al., 2020]] ) (Figure CCP5.6). Limited governance and integrated management of water resources, power and gender inequalities and level of disruption of local community practices also contribute to making risks more severe ( ''medium confidence'' ) ( [[#Lynch--2012|Lynch, 2012]] ; [[#Boelens--2014|Boelens, 2014]] ; [[#Wijngaard--2018|Wijngaard et al., 2018]] ; [[#Scott--2019|Scott et al., 2019]] ; [[#Immerzeel--2020|Immerzeel et al., 2020]] ). Consequences for hydropower are comparatively less severe than for agriculture and domestic/municipal use, although this depends on region and timing (see also [[IPCC:Wg2:Chapter:Chapter-5#5.2.2|Section 5.2.2.2]] ). For example, a study shows low risk to hydropower production in High Mountain Asia until the end of the century and even for warming levels beyond 3°C ( ''robust evidence, moderate agreement'' ) ( [[#Mishra--2020|Mishra et al., 2020]] ) ''.''

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'''Figure CCP5.6 |''' '''Risk levels assessed per AR6 WGI reference region (AR6 WGI Atlas (Gutiérrez et al.''' ''', 2021)).''' The majority of studies assessed focus on impacts up to mid-century (2030–2060) and for RCP-2.6, RCP-4.5 and RCP-6.0, which was converted into the corresponding warming level range 1.5°C–2.0°C GWL (Cross-Chapter Box CLIMATE in Chapter 1). Methodological details are provided in Section SMCCP5.4, Figure SMCCP5.1, Table SMCCP5.17 and SMCCP5.19. Due to the ''limited evidence'' available to determine risks against high GWLs and the relatively high uncertainty associated with future irrigation trends for the second half of the century (e.g., [[#Viviroli--2020|Viviroli et al., 2020]] ), assessment of risks associated with GWLs greater than 2.0°C GWL was not conducted.

Large-scale and transformative interventions can reduce the high-end impacts of changing water resources and in particular the risks of water scarcity (Section CCP5.4.1). These interventions have long lead times, are costly and may face institutional constraints ( [[IPCC:Wg2:Chapter:Chapter-4#4.7|Section 4.7]] ), resulting in adaptation shortfalls. Therefore, high-risk to very high-risk levels cannot be excluded in regions where other key risk characteristics, such as magnitude, timing and likelihood, are assessed as high due to potential losses (e.g., in many Asian regions) (Figure CC5.6, SMCCP5.4 and Table SMCCP5.16).

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