Editing IPCC:AR6/SROCC/Chapter-2 (section)

==== 2.3.1.4 Water Governance and Response Measures ====

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Cryospheric changes induced by climate change, and their effects on hydrological regime and water availability, bear relevance for the management and governance of water as a resource for communities and ecosystems (Hill, 2013 <sup>[[#fn:r421|421]]</sup> ; Beniston and Stoffel, 2014 <sup>[[#fn:r422|422]]</sup> ; Carey et al., 2017 <sup>[[#fn:r423|423]]</sup> ), particularly in areas where snow and ice contribute significantly to river runoff ( ''medium confidence'' ) (Section 2.3.1.1). However, water availability is one aspect relevant for water management and governance, given that multiple and diverse decision making contexts and governance approaches and strategies can influence how the water resource is accessed and distributed ( ''medium confidence'' ) (De Stefano et al., 2010; Beniston and Stoffel, 2014 <sup>[[#fn:r424|424]]</sup> ).

A key risk factor that influences how water is managed and governed, rests on existing and unresolved conflicts that may or may not necessarily arise exclusively from demands over shared water resources, raising tensions within and across borders in river basins influenced by snow and glacier melt (Valdés-Pineda et al., 2014 <sup>[[#fn:r425|425]]</sup> ; Bocchiola et al., 2017 <sup>[[#fn:r426|426]]</sup> ). For example, in Central Asia, competing demand for water for hydropower and irrigation between upstream and downstream countries has raised tensions (Bernauer and Siegfried, 2012 <sup>[[#fn:r427|427]]</sup> ; Bocchiola et al., 2017 <sup>[[#fn:r428|428]]</sup> ). Similarly, competing demand for water is also reported in Chile (Valdés-Pineda et al., 2014 <sup>[[#fn:r429|429]]</sup> ) and in Peru (Vuille, 2013 <sup>[[#fn:r430|430]]</sup> ; Drenkhan et al., 2015 <sup>[[#fn:r431|431]]</sup> ). Since AR5, some studies have examined the impacts and risks related to projections of cryosphere-related changes in streamflow in transboundary basins in the 21 st century, and suggest that these changes create barriers in effectively managing water in some settings ( ''medium confidence'' ) ''.'' For instance, within the transnational Indus River basin, climate change impacts may reduce streamflow by the end of this century, thus putting pressure on established water sharing arrangements between nations (Jamir, 2016 <sup>[[#fn:r432|432]]</sup> ) and subnational administrative units (Yang et al., 2014b <sup>[[#fn:r433|433]]</sup> ). In this basin, management efforts may be hampered by current legal and regulatory frameworks for evaluating new dams, which do not take into account changes in streamflow that may result from climate change (Raman, 2018 <sup>[[#fn:r434|434]]</sup> ). Within the transnational Syr Darya and Amu Darya basins in Central Asia, competition for water between multiple uses, exacerbated by reductions in flow later in this century, may hamper future coordination (Reyer et al., 2017 <sup>[[#fn:r435|435]]</sup> ; Yu et al., 2019 <sup>[[#fn:r436|436]]</sup> ). However, other evidence from Central Asia suggests that relative water scarcity may not be the only factor to exacerbate conflict in this region (Hummel, 2017 <sup>[[#fn:r437|437]]</sup> ). Overall, there is ''medium confidence'' in the ability to meet future water demands in some mountain regions, given the combined uncertainties associated with accurate projections of water supply in terms of availability and the diverse sociocultural and political contexts in which decisions on water access and distribution are taken.

Since AR5, several studies highlight that integrated water management approaches, focused on the multipurpose use of water that includes water released from the cryosphere, which are important as adaptation measures, particularly for sectors reliant on this water source to sustain energy production, agriculture, ecosystems and drinking water supply (Figure 2.9). These measures, backed by effective governance arrangements to support them, demonstrate an ability to address increasing challenges to water availability arising from climate change in the mountain cryosphere, providing co-benefits through the optimisation of storage and the release of water from high mountain reservoirs ( ''medium confidence'' ). Studies in Switzerland (e.g., Haeberli et al., 2016; Brunner et al., 2019 <sup>[[#fn:r438|438]]</sup> ), Peru (e.g., Barriga Delgado et al., 2018; Drenkhan et al., 2019 <sup>[[#fn:r439|439]]</sup> ), Central Asia (Jalilov et al., 2018 <sup>[[#fn:r440|440]]</sup> ) and Himalaya (Molden et al., 2014 <sup>[[#fn:r441|441]]</sup> ; Biemans et al., 2019 <sup>[[#fn:r442|442]]</sup> ) highlight the potential of water reservoirs in high mountains, including new reservoirs located in former glacier beds, alleviating seasonal water scarcity for multiple water usages. However, concerns are also raised in the environmental literature about their actual and potential negative impacts on local ecosystems and biodiversity hotspots, such as wetlands and peat bogs, which have been reported for small high mountain reservoirs, for example, in the European Alps (Evette et al., 2011 <sup>[[#fn:r443|443]]</sup> ) and for large dam construction projects in High Mountain Asia (e.g., Dharmadhikary, 2008).

Transboundary cooperation at regional scales are reported to further support efforts that address the potential risks to water resources in terms of its availability and its access and distribution governance (Dinar et al., 2016 <sup>[[#fn:r444|444]]</sup> ). Furthermore, the UN 2030 Agenda and its Sustainable Development Goals (SDGs) (UN, 2015) may offer additional prospects to strengthen water governance under a changing cryosphere, given that monitoring and reporting on key water-related targets and indicators, and their interaction across other SDGs, direct attention to the provision of water as a key condition for development (Section 2.4). However, there is ''limited evidence'' to date to assess their effectiveness on an evidentiary basis.

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