Editing IPCC:AR6/WGII/Chapter-4 (section)

=== 4.5.2 Projected Risks to Energy and Industrial Water Use ===

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AR5 concluded with ''high confidence'' that climate-induced changes, including changes in water flows, will affect energy production, and the actual impact will depend on the technological processes and location of energy production facilities ( [[#Arent--2014|Arent et al., 2014]] ). SR1.5 concluded with ''high confidence'' that climate change is projected to affect the hydropower production of northern European countries positively. However, Mediterranean countries like Greece, Spain and Portugal are projected to experience approximately a 10% reduction in hydropower potential under a 2°C warming level, which could be reduced by half if global warming could be limited to 1.5°C ( [[#Hoegh-Guldberg--2018|Hoegh-Guldberg et al., 2018]] ). In addition, SROCC concluded with ''high confidence'' that an altered amount and seasonality of water supply from snow and glacier melt is projected to affect hydropower production negatively ( [[#IPCC--2019a|IPCC, 2019a]] ).

Since AR5, a large number of studies have modelled future changes in hydropower production due to climate-induced changes in volume and seasonality of streamflow and changes in sediment load due to accelerated melting of cryosphere at both global ( [[#van%20Vliet--2016b|van Vliet et al., 2016b]] ; [[#Turner--2017|Turner et al., 2017]] ) and regional scales ( [[#Tarroja--2016|Tarroja et al., 2016]] ; [[#Ali--2018|Ali et al., 2018]] ; [[#de%20Jong--2018|de Jong et al., 2018]] ; [[#Tobin--2018|Tobin et al., 2018]] ; [[#Arango-Aramburo--2019|Arango-Aramburo et al., 2019]] ; [[#Carvajal--2019|Carvajal et al., 2019]] ; [[#Arias--2020|Arias et al., 2020]] ; [[#Meng--2021|Meng et al., 2021]] ).

For hydropower production at a global scale, Turner et al. (2017) projected an uncertainty in the direction of change in global hydropower production to the tune of +5% to −5% by the 2080s, under a high-emissions scenario. On the other hand, [[#van%20Vliet--2016b|van Vliet et al. (2016b)]] projected an increase in global hydropower production between +2.4% to +6.3% under RCP4.5 and RCP8.5, respectively, by the 2080s, as compared to a baseline period of 1971–2000, but with significant regional variations ( ''high confidence'' ). For example, regions like central Africa, India, central Asia and northern high-latitude areas are projected to see more than 20% increases in gross hydropower potential ( ''high confidence'' ). On the other hand, southern Europe, northern Africa, southern USA and parts of South America, southern Africa and southern Australia are projected to experience more than 20% decreases in gross hydropower potential. The Mediterranean region is projected to see almost a 40% reduction in hydropower production ( ''high confidence'' ) ( [[#Turner--2017|Turner et al., 2017]] ). On the other hand, northern Europe and India are projected to add to their hydropower production capacity due to climate change by mid-century ( ''high confidence'' ) ( [[#van%20Vliet--2016b|van Vliet et al., 2016b]] ; [[#Turner--2017|Turner et al., 2017]] ; [[#Emodi--2019|Emodi et al., 2019]] ).

In hydropower plants located in the Zambezi basin, electricity output is projected to decline by 10–20% by 2070 compared to baseline (1948–2008) under a drying climate; only marginal increases are projected under a wetting climate ( [[#Spalding-Fecher--2017|Spalding-Fecher et al., 2017]] ). In the Mekong Basin, the total hydropower generation is projected to decline by 3.0% and 29.3% under 1.5°C and 2°C, respectively ( [[#Meng--2021|Meng et al., 2021]] ). In this context, 1.5°C will come up in 2036 under RCP2.6 and in 2033, under RCP6.0; and 2°C will come up in 2056 under RCP6.0 ( [[#Frieler--2017a|Frieler et al., 2017a]] ). In India, hydropower production is projected to increase by up to 25% by the end of the 21st century due to increased temperature and precipitation under the RCP8.5 scenario. However, hydropower production is projected to decline in plants located in snow-dominated rivers due to earlier snowmelt ( [[#Ali--2018|Ali et al., 2018]] ). In Colombia, hydropower production is projected to decrease by ~10% under the RCP4.5 dry scenario by 2050 ( [[#Arango-Aramburo--2019|Arango-Aramburo et al., 2019]] ). In a sub-basin of the Amazon River (one of the hydropower hotspots in Brazil), dry-season hydropower potential is projected to decline by −7.4 to −5.4% from historical baseline conditions under RCP4.5 ( [[#Arias--2020|Arias et al., 2020]] ). In the São Francisco basin of Brazil, hydropower production is projected to reduce by −15% to −20% by 2100 under the IPCC A1B scenario ( [[#de%20Jong--2018|de Jong et al., 2018]] ), which will affect the Brazilian energy mix in the future. In Ecuador, under various policy pathways and dry and wet scenarios under RCP4.5, hydropower production is projected to increase by +7% to +21% or decline by −25% to −44% by 2050 ( [[#Carvajal--2019|Carvajal et al., 2019]] ). In Europe, different impacts are projected across different sub-regions (WGII, Chapter 13, Table 13.7- Projected climate change risks for energy supply in Europe by 2100). In northern Europe, up to 20% of hydropower potential increases are projected under 3°C warming; increases of up to 15% and 10% are projected under 2°C and 1.5°C warming levels. In Mediterranean parts of Europe, hydropower potential reductions of up to −40% are projected under 3°C warming; while reductions below −10% and −5% are projected under 2°C and 1.5°C warming levels, respectively ( [[#van%20Vliet--2016b|van Vliet et al., 2016b]] ; [[#Tobin--2018|Tobin et al., 2018]] ). Hydropower plants in Switzerland are projected to lose ~1.0 TWh of hydroelectricity production per year by 2070–2090 due to net glacier mass loss in the earlier part of the century ( [[#Schaefli--2019|Schaefli et al., 2019]] ). In the Italian Alps, under the warmest scenario of RCP8.4, up to 4% decreases in hydropower production are projected ( [[#Bombelli--2019|Bombelli et al., 2019]] ). The magnitude of change differs significantly among models. In California, USA, the average annual hydropower generation is expected to decline by 3.1% under RCP4.5 by 2040–2050, compared to the baseline 2000–2010 ( [[#Tarroja--2016|Tarroja et al., 2016]] ). In the Skagit River basin in the USA, hydropower generation is projected to increase by 19% in the winter/spring and decline by 29% in summer by the 2080s ( [[#Lee--2016|Lee et al., 2016]] ).

Apart from climate impacts on hydropower production, climate-induced flood loads and reservoir water level change may lead to dam failure under RCP2.6 and RCP4.5 scenarios ( [[#Fluixá-Sanmartín--2018|Fluixá-Sanmartín et al., 2018]] ; [[#Fluixá-Sanmartín--2019|Fluixá-Sanmartín et al., 2019]] ) ( ''medium confidence'' ). For example, the incidence of 100-year floods in the Skagit River basin in the USA and peak winter sediments are projected to increase by 49% and 335%, respectively, by 2080, necessitating fundamental changes in hydropower plant operation. Nevertheless, some risks, such as floods, will remain unmitigated even with changes in hydropower operation rules ( [[#Lee--2016|Lee et al., 2016]] ). Overall, impacts of future extreme events on energy infrastructure have been less studied than impacts of gradual changes ( [[#Cronin--2018|Cronin et al., 2018]] ). Furthermore, future hydropower development may also impact areas of high freshwater megafauna in South America, South and East Asia and in the Balkan region, and sub-catchments with a high share of threatened freshwater species are particularly vulnerable ( [[#Zarfl--2019|Zarfl et al., 2019]] ). Therefore, future hydropower dams will need to be sited carefully ( [[#Dorber--2020|Dorber et al., 2020]] ).

There is ''high confidence'' that changes in future cooling water availability are projected to affect thermoelectric production capacity negatively at global ( [[#van%20Vliet--2016b|van Vliet et al., 2016b]] ; [[#Zhou--2018b|Zhou et al., 2018b]] ) and regional scales ( [[#Bartos--2015|Bartos and Chester, 2015]] ; [[#Behrens--2017|Behrens et al., 2017]] ; [[#Ganguli--2017|Ganguli et al., 2017]] ; [[#Zhou--2018b|Zhou et al., 2018b]] ; [[#Emodi--2019|Emodi et al., 2019]] ). Global mean water temperature is projected to increase by +1°C for RCP2.6 and +2.7°C for RCP8.5 ( [[#van%20Vliet--2016b|van Vliet et al., 2016b]] ). Correspondingly, global cooling water sufficiency is projected to decline by −7.9% to −11.4% by 2040–2069 and −11.3% to −18.6% by 2070–2090 ( [[#Zhou--2018b|Zhou et al., 2018b]] ), thereby impacting thermoelectric power production.

In Asia, under a 2°C global warming scenario, coal power plants’ annual usable capacity factor in Mongolia, Southeast Asia and parts of China and India are projected to decrease due to water constraints ( [[#Wang--2019b|Wang et al., 2019b]] ). In the EU, an assessment of 1326 thermal electric plants in 818 basins projected that the number of basins with water stress would increase from 47 in 2014 to 54 in 2030 ( [[#Behrens--2017|Behrens et al., 2017]] ) with consequent impacts on cooling water supplies. In the western USA, by 2050, vulnerable power plants are projected to lose 1.1–3.0% of average summer generation capacity, which could rise to 7.2 to 8.8% loss under a 10-year drought condition ( [[#Bartos--2015|Bartos and Chester, 2015]] ). Further, 27% of thermoelectric production in the USA may be at severe risk of low-capacity utilisation due to water stress by 2030 ( [[#Ganguli--2017|Ganguli et al., 2017]] ). Thermoelectric plant capacity on the hottest summer day in the USA and EU is projected to fall by 2% under a 2°C global warming and by 3.1% under a 4°C global warming, requiring overbuilding of electricity infrastructure by 1–7% given the current energy mix portfolio ( [[#Coffel--2020|Coffel and Mankin, 2020]] ). A systematic review showed consistent decreases in mid to end of the century in thermal power production capacity due to insufficiency of cooling water in southern, western and eastern Europe ( ''high confidence'' ); North America and Oceania ( ''high confidence'' ), central, southern and western Asia ( ''high confidence'' ) and western and southern Africa ( ''medium confidence'' ) ( [[#Emodi--2019|Emodi et al., 2019]] ). Overall, apart from emissions benefits, moving away from thermal power generation to other renewable energy will also lower the chances of climate-induced curtailment of energy production ( ''high confidence'' ).

Global freshwater demand for the energy sector is projected to increase under all 2°C scenarios due to the rapid increase in electricity demand in developing countries ( [[#Fricko--2016|Fricko et al., 2016]] ). Despite the water shortage and climate change impacts, industry and energy sectors’ share in global water demand has been projected to rise to 24% by 2050 ( [[#UN%20Water--2020|UN Water, 2020]] ), which will increase the competition among various water-use sectors ( [[#Boretti--2019|Boretti and Rosa, 2019]] ). Furthermore, mining activities, which are highly dependent on sufficient water availability, are also at risk due to climate change ( [[#Aleke--2016|Aleke and Nhamo, 2016]] ). Given that some of the intensely mined regions, such as the Atacama Desert in Chile, are already water-scarce, even small changes in rainfall could destabilise water-intensive mining operations and affect the production and processing activities at mines ( [[#Odell--2018|Odell et al., 2018]] ). Overall, there is a lack of literature on the impact of climate change on future mining activities and other water-intensive industries.

In summary, globally, hydropower and thermoelectric power capacities are projected to increase and decrease, respectively, due to changes in river runoff and increases in ambient water temperatures ( ''high confidence'' ). In the future, freshwater demand for energy and industrial sectors is projected to rise significantly at the global level, triggering competition for water across sectors. Although climate change also poses risks to mining and other water-intensive industries, quantifying these risks is difficult due to limited studies.

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