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

==== 4.7.1.2 Benefits, Including Co-benefits of Water-related Adaptation Responses and Resulting Maladaptation ====

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There is no consensus in the literature about ways of measuring the effectiveness of current adaptation responses in reducing climate-related impacts ( [[#Singh--2021|Singh et al., 2021]] ). However, various methodologies, including feasibility assessment, have been deployed ( [[#Williams--2021|Williams et al., 2021]] ). Given the methodological challenges in defining and measuring the effectiveness of adaptation in reducing climate risks, in this section, we focus on outcomes of water-related adaptation across several dimensions. A total of 359 studies were identified to contain sufficiently ''robust evidence'' of documented adaptation outcomes to form the basis of this assessment (SM4.2, Table SM4.5; [[#Berrang-Ford--2021a|Berrang-Ford et al., 2021a]] ; [[#Mukherji--2021|Mukherji et al., 2021]] ). Positive outcomes denote benefits of adaptation, while negative outcomes may mean that adaptation was not effective in bringing any benefits or that it was maladaptive ( [[#Schipper--2020|Schipper, 2020]] ).

We assess outcomes across five indicators: (a) economic and financial indicators, such as improvements in crop yields and resulting incomes; increase in profits, higher savings or lesser losses from hazards; (b) impacts on vulnerable people, for example, on women, children and Indigenous Peoples; (c) water-related impacts, for example, improved water use efficiency, water saving, reduction in water withdrawals and application; (d) ecological and environmental impacts such as lesser energy use, better soil structures and better thermal comfort.; (e) institutional and sociocultural impacts such as improved social capital and stronger communities of practice, equity; and strengthening of local institutions or national policies. Of these 359 studies, 319 documented beneficial outcomes across one or more indicators, while the remaining 40 presented no beneficial outcomes. Illustrative examples are shown in Table 4.9, while the distribution of these responses with positive outcomes is shown in Figure 4.27, and indicates that economic benefits of adaptation are more common in developing countries, while benefits along ecological dimensions are more common in the developed countries,

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[[File:2518c328ae4e704d76634c50e1050e2f IPCC_AR6_WGII_Figure_4_027.png]]

'''Figure 4.27 |''' '''Top panel: location of case studies of water-related adaptation responses (996 data points from 319 studies).''' In these 996 data points, at least one positive outcome was recorded in one of the five outcome indicators. These outcome indicators are economic/financial, outcomes for vulnerable people, ecological/environmental, water-related, and sociocultural and institutional. Middle panel: the top six documented adaptation options per region as a fraction of the total of reported studies, with grey bars containing the share of all other adaptation responses. In most instances, the top six adaptation categories include nearly 3/4 of the studies. Bottom panel: The spider diagrams show the number of studies reporting beneficial outcomes for one or more dimensions for the top six adaptation options identified in each region. Due to a small number of studies in small island states, a spider diagram was not generated for the small island states.

Co-benefits are defined as mitigation benefits resulting from an adaptation response ( [[#Deng--2017|Deng et al., 2017]] ). Around a quarter of papers that documented positive adaptation outcomes also reported mitigation co-benefits. Agroforestry, community forests and forest-based adaptations are the most oft-cited examples of mitigation co-benefits ( [[#Bhatta--2015|Bhatta et al., 2015]] ; [[#Etongo--2015|Etongo et al., 2015]] ; [[#Weston--2015|Weston et al., 2015]] ; [[#Pandey--2017|Pandey et al., 2017]] ; [[#Sain--2017|Sain et al., 2017]] ; [[#Sánchez--2017|Sánchez and Izzo, 2017]] ; [[#Wood--2017|Wood et al., 2017]] ; [[#Adhikari--2018a|Adhikari et al., 2018a]] ; [[#Hellin--2018|Hellin et al., 2018]] ; [[#Aniah--2019|Aniah et al., 2019]] ; [[#Quandt--2019|Quandt et al., 2019]] ; also see Box 5.11). Other examples include mitigation benefits of climate-smart agricultural practices that reduce input intensity and help in carbon sequestration ( [[#Arslan--2015|Arslan et al., 2015]] ; [[#Somanje--2017|Somanje et al., 2017]] ), retrofitting buildings in urban areas with energy-efficient devices for lowering electricity bills and emissions ( [[#Fitzgerald--2016|Fitzgerald and Lenhart, 2016]] ) and reuse of treated wastewater for irrigation and urban uses ( [[#Morote--2019|Morote et al., 2019]] ) (Box 4.5, 4.7.6).

Not all adaptation responses reduce risks, and some may have long-term maladaptive outcomes, even if they are beneficial in the short term. Maladaptation often stems from poor planning and implementation of adaptation responses and because of not addressing the root causes of vulnerability ( [[#Schipper--2020|Schipper, 2020]] ; [[#Eriksen--2021|Eriksen et al., 2021]] ). Of the 319 case studies where adaptation response was found to have some beneficial outcomes, around one third of them also mentioned the possibility of maladaptation. Migration can often have maladaptive outcomes because migration can exacerbate the inherent vulnerabilities of migrants ( [[#4.6.8|Section 4.6.8]] ). For example, slum dwellers in cities may earn higher incomes, but their quality of life worsens ( [[#Ayeb-Karlsson--2016|Ayeb-Karlsson et al., 2016]] ). In some instances, even wage rates in migration hotspots can remain low due to the high volume of the migrant population ( [[#Fenton--2017b|Fenton et al., 2017b]] ); as such, it does not help buffer consumption against rainfall shocks ( [[#Gao--2018|Gao and Mills, 2018]] ). Migration also has gendered impacts, with girls from migrating families being taken out of school ( [[#Gioli--2014|Gioli et al., 2014]] ) or interrupting children’s education overall ( [[#Warner--2014|Warner and Afifi, 2014]] ). In planned relocation from vulnerable urban slums, relocation sites can be far from job sites and increase social conflicts ( [[#Tauhid--2018|Tauhid and Zawani, 2018]] ).

Adaptation responses that focus on improving incomes through production intensification can have maladaptive outcomes. An oft-cited example of this is groundwater overuse as a result of irrigation intensification. There is widespread evidence of groundwater overuse in many countries in Africa ( [[#Mapfumo--2017|Mapfumo et al., 2017]] ), in the Middle East and North Africa ( [[#Petit--2017|Petit et al., 2017]] ; [[#Daly-Hassen--2019|Daly-Hassen et al., 2019]] ), in Asia ( [[#Burchfield--2016|Burchfield and Gilligan, 2016]] ; [[#Zhang--2016b|]] [[#Zhang--2016|Zhang et al., 2016]] b ; [[#Kattumuri--2017|Kattumuri et al., 2017]] ), in Spain ( [[#Petit--2017|Petit et al., 2017]] ) and in Australia ( [[#Kirby--2014|Kirby et al., 2014]] ) (Sections 4.2.6, 4.6.2, Box 4.3). Intensification-based approaches also increase costs of cultivation ( [[#Mussetta--2016|Mussetta et al., 2016]] ; [[#Wang--2018|Wang and Chen, 2018]] ; [[#Quan--2019|Quan et al., 2019]] ), and can lead to more use of fertilisers and herbicides ( [[#Thierfelder--2015|Thierfelder et al., 2015]] ; [[#Sujakhu--2016|Sujakhu et al., 2016]] ; [[#Khanal--2018a|Khanal et al., 2018a]] ; [[#Yamba--2019|Yamba et al., 2019]] ). Diversification away from food crops can also compromise domestic food security ( [[#Kloos--2014|Kloos and Renaud, 2014]] ; [[#Brüssow--2017|Brüssow et al., 2017]] ).

Even interventions that have positive carbon co-benefits like forestry and agroforestry can have maladaptive consequences on land and water resources, especially if inappropriate species ( [[#Etongo--2015|Etongo et al., 2015]] ) with higher water demands are grown ( [[#Krishnamurthy--2019|Krishnamurthy et al., 2019]] ) ( [[#4.7.6|Section 4.7.6]] ).

In summary, current adaptation responses have benefits across several dimensions. In developing countries, most adaptation measures improve economic outcomes ( ''high confidence'' ). Adaptation responses also have benefits in terms of water outcomes and environmental and ecological parameters, and these benefits are more commonly manifested in developed countries ( ''high confidence'' ). Of the papers assessed for water-related adaptation, roughly one fourth reported adaptation co-benefits ( ''high confidence'' ). In contrast, one third of studies reported maladaptive outcomes, now or in the future ( ''high confidence'' ), emphasizing the importance of looking at synergies and trade-offs. Despite many adaptation case studies, there is a knowledge gap in understanding if the benefits of adaptation also translate into a reduction of climate impacts, and if so, to what extent, and under what conditions ( ''high confidence'' ). In view of this critical knowledge gap, our assessment is limited to benefits of current adaptation responses.

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