Editing IPCC:AR6/SRCCL/Chapter-3 (section)

=== 3.6.4 Limits to adaptation, maladaptation, and barriers for mitigation ===

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Chapter 16 in the IPCC Fifth Assessment Report (AR5) (Klein et al. 2015 <sup>[[#fn:r1799|1799]]</sup> ) discusses the existence of soft and hard limits to adaptation, highlighting that values and perspectives of involved agents are relevant to identify limits (Sections 4.8.5.1 and 7.4.9). In that sense, adaptation limits vary from place to place and are difficult to generalise (Barnett et al. 2015 <sup>[[#fn:r1486|1486]]</sup> ; Dow et al. 2013 <sup>[[#fn:r1800|1800]]</sup> ; Klein et al. 2015 <sup>[[#fn:r1801|1801]]</sup> ). Currently, there is a lack of knowledge on adaptation limits and potential maladaptation to combined effects of climate change and desertification (see Section 4.8.6 for discussion on resilience, thresholds, and irreversible land degradation, also relevant for desertification). However, the potential for residual risks (those risks which remain after adaptation efforts were taken, irrespective of whether they are tolerable or not, tolerability being a subjective concept) and maladaptive outcomes is high ( ''high confidence'' ). Some examples of residual risks are illustrated below in this section. Although SLM measures can help lessen the effects of droughts, they cannot fully prevent water stress in crops and resulting lower yields (Eekhout and de Vente 2019 <sup>[[#fn:r1487|1487]]</sup> ). Moreover, although in many cases SLM measures can help reduce and reverse desertification, there would still be short-term losses in land productivity. Irreversible forms of land degradation (for example, loss of topsoil, severe gully erosion) can lead to the complete loss of land productivity. Even when solutions are available, their costs could be prohibitive, presenting the limits to adaptation (Dixon et al. 2013 <sup>[[#fn:r1488|1488]]</sup> ). If warming in dryland areas surpasses human thermal physiological thresholds (Klein et al. 2015; Waha et al. 2013 <sup>[[#fn:r1489|1489]]</sup> ), adaptation could eventually fail (Kamali et al. 2018 <sup>[[#fn:r1490|1490]]</sup> ). Catastrophic shifts in ecosystem functions and services (for example coastal erosion (Chen et al. 2015; Schneider and Kéfi 2016 <sup>[[#fn:r1491|1491]]</sup> ) (Section 4.9.8)) and economic factors can also result in adaptation failure (Evans et al. 2015). Despite the availability of numerous options that contribute to combating desertification, climate change adaptation and mitigation, there are also chances of maladaptive actions ( ''medium confidence'' ) (see Glossary). Some activities favouring agricultural intensification in dryland areas can become maladaptive due to their negative impacts on the environment ( ''medium confidence'' ). Agricultural expansion to meet food demands can come through deforestation and consequent diminution of carbon sinks (Godfray and Garnett 2014 <sup>[[#fn:r1492|1492]]</sup> ; Stringer et al. 2012 <sup>[[#fn:r1493|1493]]</sup> ). Agricultural insurance programmes encouraging higher agricultural productivity and measures for agricultural intensification can result in detrimental environmental outcomes in some settings (Guodaar et al. 2019 <sup>[[#fn:r1494|1494]]</sup> ; Müller et al. 2017 <sup>[[#fn:r1495|1495]]</sup> ) (Table 6.12). Development of more drought-tolerant crop varieties is considered as a strategy for adaptation to shortening rainy seasons, but this can also lead to a loss of local varieties (Al Hamndou and Requier-Desjardins 2008 <sup>[[#fn:r1496|1496]]</sup> ). Livelihood diversification to collecting and selling firewood and charcoal production can exacerbate deforestation (Antwi-Agyei et al. 2018 <sup>[[#fn:r1497|1497]]</sup> ). Avoiding maladaptive outcomes can often contribute both to reducing the risks from climate change and combating desertification (Antwi-Agyei et al. 2018 <sup>[[#fn:r1498|1498]]</sup> ). Avoiding, reducing and reversing desertification would enhance soil fertility, increase carbon storage in soils and biomass, thus reducing carbon emissions from soils to the atmosphere (Section 3.7.2 and Cross-Chapter Box 2 in Chapter 1). In specific locations, there may be barriers for some of these activities. For example, afforestation and reforestation programmes can contribute to reducing sand storms and increasing carbon sinks in dryland regions (Chu et al. 2019) (Sections 3.6.1 and 3.7.2). However, implementing agroforestry measures in arid locations can be constrained by lack of water (Apuri et al. 2018 <sup>[[#fn:r1499|1499]]</sup> ), leading to a trade-off between soil carbon sequestration and other water uses (Cao et al. 2018). Thus, even when solutions are available, social, economic and institutional constraints could post barriers to their implementation ( ''medium confidence'' ).

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