Editing IPCC:AR6/WGII/Chapter-16 (section)

==== 16.3.2.4 Adaptation Effectiveness, Adequacy and Risk Reduction ====

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Despite a lack of systematic methods for assessing general adaptation effectiveness, there is some evidence of risk reduction for particular places and hazards, especially flood and heat vulnerability. There is some evidence of a reduction in global vulnerability, particularly for flood risk ( [[#Jongman--2015|Jongman et al., 2015]] ; [[#Tanoue--2016|Tanoue et al., 2016]] ; [[#Miao--2019|Miao, 2019]] ) and extreme heat ( [[#Bobb--2014|Bobb et al., 2014]] ; [[#Boeckmann--2014|Boeckmann and Rohn, 2014]] ; [[#Gasparrini--2015|Gasparrini et al., 2015]] ; [[#Arbuthnott--2016|Arbuthnott et al., 2016]] ; [[#Chung--2017|Chung et al., 2017]] ; [[#Sheridan--2018|Sheridan and Allen, 2018]] ; [[#Folkerts--2020|Folkerts et al., 2020]] ). Investment in flood protection, including building design and monitoring and forecasting, have reduced flood-related mortality over time and are cost-effective (Bouwer and Jonkman 2018; Ward et al. 2017). Declining heat sensitivity, primarily reported in developed nations, has also been observed, and has been linked to air conditioning, reduced social vulnerability and improved population health ( [[#Boeckmann--2014|Boeckmann and Rohn, 2014]] ; [[#Chung--2017|Chung et al., 2017]] ; [[#Kinney--2018|Kinney, 2018]] ; [[#Sheridan--2018|Sheridan and Allen, 2018]] ). [[#Formetta--2019|Formetta and Feyen (2019)]] demonstrate declining global all-cause mortality and economic loss due to extreme weather events over the past four decades, with the greatest reductions in low-income countries, and with reductions correlated with wealth. Studies that correlate changes in mortality or economic losses with wealth indicators, to infer changes in vulnerability or exposure, lack direct empirical measures of vulnerability or exposure and are limited in their ability to assess how indirect effects of extreme events (e.g., morbidity, relocation, social disruption) may have changed or how changes may redistribute risk across populations.

There remain persistent difficulties in defining and measuring adaptation effectiveness and adequacy for many climate risks. No studies have systematically assessed the adequacy and effectiveness of adaptation at a global scale, across nations or sectors, or for different levels of warming. There has, however, been progress in operationalising assessment of adaptation feasibility (Cross-Chapter Box FEASIB in Chapter 18). Effectiveness of adaptation-related responses reflects whether a particular response actually reduces climate risk, typically through reductions in vulnerability and exposure (Figure 1.7 in [[IPCC:Wg2:Chapter:Chapter-1#1.4|Section 1.4]] ). Some adaptation-related responses may increase risk or create new risks (maladaptation) or have no or negligible impact on risk. Adequacy of adaptation-related responses refers to the extent to which responses are collectively sufficient to reduce the risks or impacts of climate change (Figure 1.7 in [[IPCC:Wg2:Chapter:Chapter-1#1.4|Section 1.4]] ). A set of adaptation-related responses may, for example, result in reduced climate risk (effectiveness), but these reductions may be insufficient to offset the level of risk and avoid loss and damages. Feasibility reflects the degree to which climate responses are possible or desirable, and integrates consideration of potential effectiveness. A feasibility assessment drawing on these methods is presented in Cross-Chapter Box FEASIB in Chapter 18.

Global adaptation is predominantly slow, siloed and incremental with little evidence of transformative adaptation ( ''high confidence'' ). In the absence of a general method to assess the adequacy of adaptation actions, we assessed evidence for transformational adaptation documented in peer-reviewed publications identified by a global stock-taking initiative ( [[#Berrang-Ford--2021b|Berrang-Ford et al., 2021b]] ) and in other AR6 chapters (2–15) (see Supplemental Material, SM16.1 for details). ‘Transformational adaptation’ refers to the degree to which adaptations have been implemented widely (scope), reflect major shifts (depth), occur rapidly (speed) and challenge limits to adaptation (limits, [[#Pelling--2015|Pelling et al., 2015]] ; [[#Few--2017|Few et al., 2017]] ; [[#Termeer--2017|Termeer et al., 2017]] , Table 16.1).

Based on the literature, the overall transformative nature of adaptation across most global regions and sectors is low ( ''high confidence)'' (Figure 16.6). Documented adaptations tend to involve minor modifications to usual practices taken to address extreme weather conditions ( ''high confidence'' ). For example, changing crop variety or timing of crop planting to address floods or droughts, new types of irrigation, pursuing supplementary livelihoods, and home elevations are widely reported but typically do not reflect radical or novel shifts in practice or values and are therefore considered low depth ( ''high confidence'' ) (see SM16.1 for more examples). Adaptations documented in the literature are also frequently focused on a single sector or small geographic area ( ''high confidence'' ). Actions taken by individuals or households are generally small in scope ( [[#Hintz--2018|Hintz et al., 2018]] ; [[#Hlahla--2018|Hlahla and Hill, 2018]] ) unless they are widely adopted (e.g., by farmers across a region) or address numerous aspects of life. National policies are more likely to be broad in scope ( [[#Puthucherril--2014|Puthucherril et al., 2014]] ), although they frequently focus on a single sector and are therefore still limited. The speed of adaptation is rarely noted explicitly, but the average speed documented in the literature is slow ( ''medium confidence'' ) (Cross-Chapter Box FEASIB in Chapter 18). Adaptation efforts frequently encounter either soft or hard limits (see [[#16.4|Section 16.4]] ), but there is ''limited evidence'' to suggest these limits are being challenged or overcome ( ''medium confidence'' ).

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'''Figure 16.6 |''' '''Evidence of transformative adaptation by sector and region.''' Evidence of transformational adaptation does not imply effectiveness, equity or adequacy. Evidence of transformative adaptation is assessed based on the scope, speed, depth and ability to challenge limits of responses reported in the scientific literature (see Supplementary Material for methods). Studies relevant to multiple regions or sectors are included in assessment for each relevant sector/region.

Few documented responses are simultaneously widespread, rapid and novel ( ''high confidence'' ). Some examples exist, such as village relocations or creation of new multi-stakeholder resource governance systems ( [[#Schwan--2018|Schwan and Yu, 2018]] ; [[#McMichael--2020|McMichael and Katonivualiku, 2020]] ), but these are rare. In general, adaptations that are broad in scope tend to be slow ( ''medium confidence'' ), suggesting that achieving high transformation in all four categories (depth, scope, speed and limits) may be particularly challenging or even involve trade-offs.

'''Table 16.1 |''' Evidence of transformational adaptation assessed across four components (depth, scope, speed and limits). Transformational adaptation does not imply adequacy or effectiveness of adaptation (low transformation may be sufficient for some climate risks, and high transformation may be insufficient to offset others). Nevertheless, these components provide a systematic framework for tracking adaptation progress and assessing the state of adaptation-related responses. The ‘high’ categories across each component reflect more transformative scenarios. Methods are described in SM16.1.

{| class="wikitable"
|-
!
! colspan="3"| Transformative potential of adaptation

|-
| Dimensions

| '''Low'''

| '''Medium'''

| '''High'''

|-
| '''Overall'''

| ''Adaptation is largely sporadic and consists of small adjustments to Business-As-Usual. Coordination and mainstreaming are limited and fragmented.''

| ''Adaptation is expanding and increasingly coordinated, including wider implementation and multi-level coordination.''

| ''Adaptation is widespread and implemented at or very near its full potential across multiple dimensions.''

|-
| '''Depth'''

| Adaptations are largely expansions of existing practices, with minimal change in underlying values, assumptions or norms.

| Adaptations reflect a shift away from existing practices, norms or structures to some extent.

| Adaptations reflect entirely new practices involving deep structural reform, complete change in mindset, major shifts in perceptions or values, and changing institutional or behavioural norms.

|-
| '''Scope'''

| Adaptations are largely localised and fragmented, with ''limited evidence'' of coordination or mainstreaming across sectors, jurisdictions or levels of governance.

| Adaptations affect wider geographic areas, multiple areas and sectors, or are mainstreamed and coordinated across multiple dimensions.

| Adaptations are widespread and substantial, including most possible sectors, levels of governance, and actors.

|-
| '''Speed'''

| Adaptations are implemented slowly.

| Adaptations are implemented moderately quickly.

| Change is considered rapid for a given context.

|-
| '''Limits'''

| Adaptations may approach but do not exceed or substantively challenge soft limits.

| Adaptations may overcome some soft limits but do not challenge or approach hard limits.

| Adaptations exceed many soft limits and approach or challenge hard limits.

|}

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