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

== 3.6 Planned Adaptation and Governance to Achieve the Sustainable Development Goals ==

<div id="3.6.1" class="h2-container"></div>

<span id="introduction-4"></span>
=== 3.6.1 Introduction ===

<div id="h2-20-siblings" class="h2-siblings"></div>

Human adaptation comprises an array of measures (adaptation options; [[#IPCC--2014a|IPCC, 2014a]] ) that modulate harm or exploit opportunities from climate change ( [[IPCC:Wg2:Chapter:Chapter-1#1.2.1.3|Section 1.2.1.3]] ). Adaptation options that respond to key ocean and coastal risks ( [[#3.4|Section 3.4]] ) focus on individuals, livelihoods and economic sectors that benefit from ocean and coastal ecosystem services ( [[#3.5|Section 3.5]] ). AR5 concluded that local adaptation measures would not alone be enough to offset global effects of increased climate change on marine and coastal ecosystems, and that mitigation of emissions would also be necessary ( ''high confidence'' ) (Table 3.27; [[#Pörtner--2014|Pörtner et al., 2014]] ; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ). SROCC assessed that ecosystem-based adaptation, including MPAs ( ''high confidence'' ) ( [[#Bindoff--2019a|Bindoff et al., 2019a]] ) and adaptive management, are effective to reduce climate-change impacts ( [[#IPCC--2018|IPCC, 2018]] ; [[#IPCC--2019b|IPCC, 2019b]] ), but that existing marine governance is insufficient to provide an effective adaptation response in the marine ecosystem ( ''high confidence'' ) ( [[#IPCC--2019c|IPCC, 2019c]] ).

'''Table 3.27 |''' Conclusions from previous IPCC assessments about implemented adaptation, enablers and limits, and contribution to Sustainable Development Goals (SDGs)

{| class="wikitable"
|-
!
! AR5

! SR15

! SROCC

|-
| Degree of implementation ( [[#3.6.3.1|Section 3.6.3.1]] )

| ‘The analysis and implementation of coastal adaptation towards climate-resilient and sustainable coasts has progressed more

significantly in developed countries than in developing countries ( ''high confidenc'' e)’

( [[#Wong--2014|Wong et al., 2014]] ).

| ‘Adaptation (to SLR) is

already happening ( ''high confidence'' ) and will remain important over

multi-centennial time scales’

( [[#Hoegh-Guldberg--2018a|Hoegh-Guldberg et al., 2018a]] ).

| ‘A diversity of adaptation responses to coastal impacts and risks have been implemented around the world, but mostly as a reaction to current coastal risk or experienced disasters ( ''high confidence'' )’

( [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ).

|-
| Conservation and restoration

( [[#3.6.3.2|Section 3.6.3.2]] )

| ‘With continuing climate change, local adaptation measures (such as conservation) or a reduction in human activities (such as

fishing) may not sufficiently offset global-scale effects on marine ecosystems ( ''high confidence'' )’

( [[#Pörtner--2014|Pörtner et al., 2014]] ).

| ‘Existing and restored natural coastal ecosystems may be effective in reducing the adverse impacts of rising sea levels and intensifying storms by protecting coastal and deltaic regions ( ''medium confidence'' )’

( [[#Hoegh-Guldberg--2018a|Hoegh-Guldberg et al., 2018a]] ).

| ‘Ecosystem restoration may be able to locally reduce climate risks ( ''medium confidence'' ) but at relatively high cost and effectiveness limited to low-emissions scenarios and to less-sensitive ecosystems ( ''high confidence'' )’

( [[#Bindoff--2019a|Bindoff et al., 2019a]] ).

|-
| Enablers, barriers and limits of adaptation ( [[#3.6.3.3|Section 3.6.3.3]] )

| ‘Adaptation strategies for ocean regions beyond coastal waters are generally poorly developed but will benefit from international legislation and expert networks, as well as marine spatial planning ( ''high agreement'' )’

( [[#Hoegh-Guldberg--2014|Hoegh-Guldberg et al., 2014]] ).

| ‘Lower rates of change [associated with a 1.5°C temperature increase] enhance the ability of natural and human systems to adapt, with substantial benefits for a wide range of terrestrial, freshwater, wetland, coastal and ocean ecosystems (including coral reefs) ( ''high confidence'' )’

( [[#Hoegh-Guldberg--2018a|Hoegh-Guldberg et al., 2018a]] ).

| ‘There are a broad range of identified barriers and limits

for adaptation to climate change in ecosystems and human systems ( ''high confidence'' ). Limitations include [...] availability of technology, knowledge and financial support, and existing governance structures ( ''medium confidence'' )

( [[#Bindoff--2019a|Bindoff et al., 2019a]] ).

Existing ocean-governance structures are already facing multi-dimensional, scale-related challenges because of climate change [...] ( ''high confidence'' )’

( [[#Bindoff--2019a|Bindoff et al., 2019a]] ).

|-
| SDGs and other policy frameworks ( [[#3.6.4|Section 3.6.4]] )

| ‘Overall, there is a strong need to develop ecosystem-based monitoring and adaptation strategies to mitigate rapidly growing risks and uncertainties to the coastal and oceanic industries, communities and nations ( ''high agreement'' )’

( [[#Hoegh-Guldberg--2014|Hoegh-Guldberg et al., 2014]] ).

| ‘Adaptation strategies can result in trade-offs with and among the SDGs ( ''medium evidence, high agreement'' )’

( [[#Roy--2018|Roy et al., 2018]] ).

| ‘Achieving [the SDGs] and charting Climate Resilient Development Pathways depends in part on ambitious and sustained mitigation efforts to contain SLR coupled with effective adaptation actions to reduce SLR impacts and risk ( ''medium evidence, high agreement'' )’

( [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ).

|}

This section builds on the SROCC assessment of the portfolio of available solutions, their applicability and their effectiveness in reducing climate-change-induced risks to ocean and coastal ecosystems. [[#3.6.2|Section 3.6.2]] assesses the set of planned adaptation measures. [[#3.6.3|Section 3.6.3]] assesses implementation of adaptation solutions and the enablers, barriers and limitations that affect their feasibility. [[#3.6.4|Section 3.6.4]] evaluates the contribution of planned adaptation to the Sustainable Development Goals (SDGs) and other policy-relevant frameworks, and [[#3.6.5%20|Section 3.6.5]] synthesises emerging evidence about best practices.

<div id="3.6.2" class="h2-container"></div>

<span id="adaptation-solutions"></span>
=== 3.6.2 Adaptation Solutions ===

<div id="h2-21-siblings" class="h2-siblings"></div>

Adaptation in ocean and coastal ecosystems continues to be informed primarily by theory, as there is still ''limited evidence'' about implemented solutions ( ''high agreement'' ) ( [[#Seddon--2020|Seddon et al., 2020]] ) and their success across regions, especially in low-income nations ( [[#Chausson--2020|Chausson et al., 2020]] ). Adapting to climate change depends on society’s ability and willingness to anticipate the change, recognise its effects, plan to accommodate its consequences ( [[#Ling--2019|Ling and Hobday, 2019]] ; [[#Wilson--2020b|Wilson et al., 2020b]] ) and implement a coordinated portfolio of informed solutions. Here, the complete portfolio of adaptation solutions is assessed using the taxonomy of [[#Abram--2019|Abram et al. (2019)]] : (1) socio-institutional adaptation, (2) built infrastructure and technology, and (3) marine and coastal nature-based solutions (NbS) (Figure 3.23).

<div id="_idContainer104" class="Figure"></div>

[[File:f7a83a5d5165c1a48b109a75653d5687 IPCC_AR6_WGII_Figure_3_023.png]]

'''Figure 3.23 |''' '''Adaptation solutions for ocean and coastal ecosystems that address climate-change risk in different ocean ecosystems, communities and economic sectors.''' Box colour indicates confidence in the solution’s potential to reduce mid-term risks (based on the amount of evidence and agreement supporting the solutions; see SM3.5.1 for full assessment). The feasibility and effectiveness of each solution (low, medium or high) indicates its ability to support ecosystems and societies as they adapt to climate change impacts, based on Table 3.SM.3.

<div id="3.6.2.1" class="h3-container"></div>

<span id="socio-institutional-adaptation"></span>
==== 3.6.2.1 Socio-Institutional Adaptation ====

<div id="h3-35-siblings" class="h3-siblings"></div>

Increasing evidence shows that an effective solution portfolio includes social and institutional adaptation (Figure 3.23, top; Table 3.28). Social adaptation to climate change is already occurring, as people use strategies ranging from accommodating change, to coping, adapting and transforming their livelihoods ( [[#Béné--2018|Béné and Doyen, 2018]] ; [[#Fedele--2019|Fedele et al., 2019]] ; [[#Galappaththi--2019|Galappaththi et al., 2019]] ; [[#Barnes--2020|Barnes et al., 2020]] ; [[#Ojea--2020|Ojea et al., 2020]] ; [[#Green--2021c|Green et al., 2021c]] ). Although management and institutions have major roles in adaptation ( [[#Gaines--2018|Gaines et al., 2018]] ; [[#Barange--2019|Barange, 2019]] ), marine governance is impeded by increasing numbers of often-competing users and uses ( [[#Boyes--2014|Boyes and Elliott, 2014]] ); sector-led, fragmented efforts ( [[#Nunan--2020|Nunan et al., 2020]] ); and a legal framework less clear than those on land ( [[#Crespo--2019|Crespo et al., 2019]] ; [[#Guggisberg--2019|Guggisberg, 2019]] ). Future social responses depend on warming levels and on the institutional, socioeconomic and cultural constructs that allow or limit livelihood changes ( ''medium confidence'' ) (Chapter 18; [[#Galappaththi--2019|Galappaththi et al., 2019]] ; [[#Ford--2020|Ford et al., 2020]] ; [[#Green--2021c|Green et al., 2021c]] ). Both social and institutional transformations are needed to change the structures of power, culture, politics and/or identity associated with marine ecosystems ( [[IPCC:Wg2:Chapter:Chapter-1#1.5.2|Section 1.5.2]] ; [[#Wilson--2020b|Wilson et al., 2020b]] ). Ideally, institutional and social adaptation will work together to sustain knowledge systems and education, enhance participation and social inclusion, facilitate livelihood support and transformational change of dependent coastal communities, provide economic and financial instruments, and include polycentric and multi-level governance of transboundary management ( [[#Fedele--2019|Fedele et al., 2019]] ; [[#Fulton--2019|Fulton et al., 2019]] ).

'''Table 3.28 |''' Assessment of socio-institutional adaptation solutions to reduce mid-term climate impacts in oceans and coastal ecosystems a

{| class="wikitable"
|-
! Solution

! Confidence in solution (mid-term potential)

! Contribution to adaptation

! Selected references

! Examples of implementation

|-
| Knowledge diversity

| ''High confidence''

| Consideration of IK and LK systems is beneficial to communities, increases their resilience and is relevant and transferable beyond the local scale.

| [[#Norström--2020|Norström et al. (2020)]] ; [[#Petzold--2020|Petzold et al. (2020)]] ; [[#Gianelli--2021|Gianelli et al. (2021)]] ; [[#Schlingmann--2021|Schlingmann et al. (2021)]]

| Ecotourism ( [[#3.6.3.1.3|Section 3.6.3.1.3]] ), conservation ( [[#3.6.3.2|Section 3.6.3.2.1]] )

|-
| Socially inclusive policies

| ''High confidence''

| Policies that promote participation of a diversity of groups are able to address existing vulnerabilities in coastal communities and promote adaptation and transformational change.

| Brodie [[#Rudolph--2020|Rudolph et al. (2020)]] ; [[#Ford--2020|Ford et al. (2020)]] ; [[#Friedman--2020|Friedman et al. (2020)]]

| Finance ( [[#3.6.3|Section 3.6.3.4.2]] )

|-
| Participation

| ''Medium confidence''

| Participation in decision making and adaptation processes is recommended across a range of different hazards and contexts, and has the potential to improve adaptation outcomes.

| Brodie [[#Rudolph--2020|Rudolph et al. (2020)]] ; [[#Claudet--2020a|Claudet et al. (2020a)]] ; [[#Hügel--2020|Hügel and Davies, 2020]] ); [[#Sumaila--2021|Sumaila et al. (2021)]]

| Fisheries and mariculture ( [[#3.6.3.1.2|Section 3.6.3.1.2]] ), Indigenous Peoples ( [[#3.6.3|Section 3.6.3.4.1]] )

|-
| Livelihood diversification

| ''Medium confidence''

| Livelihood diversification in communities dependent on marine and coastal ecosystems reduces climate risks and confers flexibility to individuals, which is key to adaptive capacity.

| [[#Blanchard--2017|Blanchard et al. (2017)]] ; [[#Cinner--2019|Cinner and Barnes (2019)]] ; [[#Shaffril--2020|Shaffril et al. (2020)]] ; [[#Owen--2020|Owen (2020)]] ; [[#Pinsky--2021|Pinsky (2021)]] ; [[#Taylor--2021|Taylor et al. (2021)]]

| Fisheries and mariculture ( [[#3.6.3.1.2|Section 3.6.3.1.2]] ), coastal communities (Cross-Chapter Box SLR in Chapter 3), tourism ( [[#3.6.3.1.3|Section 3.6.3.1.3]] )

|-
| Mobility

| ''Medium confidence''

| When individuals are given the choice about mobility, they may elect to use this response to minimise climate risks and benefit their livelihoods.

| [[#Barnett--2018|Barnett and McMichael (2018)]]

| Fisheries and mariculture ( [[#3.6.3.1.2|Section 3.6.3.1.2]] )

|-
| Migration

| ''Low confidence''

| Migration often involves different spatial and temporal scales than mobility. Migration could be considered an adaptation solution for some coastal and island populations in the cases of extreme events, but also as a response to more gradual changes (e.g., coastal erosion from sea level rise).

| [[#Maharjan--2020|Maharjan et al. (2020)]] ; [[#Biswas--2021|Biswas and Mallick (2021)]] ; [[#Zickgraf--2021|Zickgraf (2021)]]

| Coastal livelihoods ( [[#3.6.3.1.1|Section 3.6.3.1.1]] )

|-
| Finance and market mechanisms

| ''High confidence''

| Financial mechanisms and credit provision for marine-dependent livelihoods are effective for overcoming impacts from SLR, extreme events and other climate-induced drivers.

| Shaffril et al. (2017); [[#Dunstan--2018|Dunstan et al. (2018)]] ; [[#Hinkel--2018|Hinkel et al. (2018)]] ; [[#Moser--2019|Moser et al. (2019)]] ; [[#Sainz--2019|Sainz et al. (2019)]] ; Woodruff et al. (2020)

| Economic dimensions ( [[#3.6.3|Section 3.6.3.4.2]] )

|-
| Disaster response programmes

| ''High confidence''

| Disaster response programmes confer resilience to communities and contribute to adaptation, when designed to be inclusive, participatory and adaptive.

| [[#Nurhidayah--2019|Nurhidayah and McIlgorm (2019)]]

| Climate services ( [[#3.6.3|Section 3.6.3.4.3]] ) '','' tourism cruise-ship sector ( [[#3.6.3.1.3|Section 3.6.3.1.3]] )

|-
| Multi-level ocean governance

| ''High confidence''

| The multi-scale nature of ocean and coastal climate-change risk demands adaptation solutions at multiple levels of governance that consider the objectives and perceptions of all stakeholders to support local implementation of broad strategies.

| [[#Miller--2018|Miller et al. (2018)]] ; [[#Gilfillan--2019|Gilfillan (2019)]] ; [[#Holsman--2019|Holsman et al. (2019)]] ; [[#Obura--2021|Obura et al. (2021)]]

| Policy frameworks ( [[#3.6.4.3|Section 3.6.4.3]] )

|-
| Institutional transboundary agreements

| ''Medium confidence''

| Institutional agreements for the management of transboundary marine resources are key for a sustainable future given current impacts on marine species distribution due to climate change.

| [[#Engler--2020|Engler (2020)]] ; [[#Mason--2020|Mason et al. (2020)]] ; [[#Oremus--2020|Oremus et al. (2020)]] ; [[#Melbourne-Thomas--2021|Melbourne-Thomas et al. (2021)]]

| Fisheries ( [[#3.6.3.1.2|Section 3.6.3.1.2]] ; Cross-Chapter Box MOVING SPECIES in Chapter 5)

|}

(a) Confidence is assessed in SM3.5.1. Feasibility and effectiveness are assessed in Figure 3.24.

<div id="3.6.2.2" class="h3-container"></div>

<span id="built-infrastructure-and-technology"></span>
==== 3.6.2.2 Built Infrastructure and Technology ====

<div id="h3-36-siblings" class="h3-siblings"></div>

Engineering and technology support marine and coastal adaptation (Table 3.29). Built infrastructure includes engineered solutions that protect, accommodate or relocate coastal assets using hard engineering, like seawalls, and soft engineering, such as beach and shore nourishment (Cross-Chapter Box SLR in Chapter 3). Technological tools include early-warning systems for extreme events ( [[#Bindoff--2019a|Bindoff et al., 2019a]] ; [[#Collins--2019a|Collins et al., 2019a]] ), improved forecast and hindcast models ( [[#Winter--2020|Winter et al., 2020]] ; [[#Davidson--2021|Davidson et al., 2021]] ; [[#Spillman--2021|Spillman and Smith, 2021]] ) and environmental monitoring ( [[#Claudet--2020a|Claudet et al., 2020a]] ; [[#Wilson--2020a|Wilson et al., 2020a]] ; [[#Melbourne-Thomas--2021|Melbourne-Thomas et al., 2021]] ) that support informed decision making ( [[#Tommasi--2017|Tommasi et al., 2017]] ; [[#Rilov--2020|Rilov et al., 2020]] ; A. [[#Maureaud--2021|Maureaud et al., 2021]] ). Emerging adaptation technologies, such as habitat development, active restoration and assisted evolution ( [[#Boström-Einarsson--2020|Boström-Einarsson et al., 2020]] ; [[#Kleypas--2021|Kleypas et al., 2021]] ), intend to accelerate recovery of damaged ecosystems and promote ecological adaptation to climate change ( [[#Jones--2018a|Jones et al., 2018a]] ; [[#Boström-Einarsson--2020|Boström-Einarsson et al., 2020]] ; [[#Kleypas--2021|Kleypas et al., 2021]] ).

'''Table 3.29 |''' Assessment of built infrastructure and technology solutions to reduce mid-term climate impacts in oceans and coastal ecosystems a

{| class="wikitable"
|-
! Solution

! Confidence in solution (mid-term potential)

! Contribution to adaptation

! Selected references

! Examples of implementation

|-
| Accommodation and relocation

| ''High confidence''

| Asset modification and relocation of livelihoods to adapt to sea level rise, extreme events and coastal erosion.

| [[#Hanson--2020|Hanson and Nicholls (2020)]] ; [[#Monios--2020|Monios and Wilmsmeier (2020)]] ; [[#Zickgraf--2021|Zickgraf (2021)]]

| Cross-Chapter Box SLR in Chapter 3, coastal development ( [[#3.6.3.1.1|Section 3.6.3.1.1]] )

|-
| Protection and beach and shore nourishment

| ''Medium confidence''

| Protection of coastal ecosystems with interventions, such as beach and shore nourishment, is a common response to beach erosion around the world, and an alternative to hard protection structures such as seawalls.

| Pinto et al. (2020); [[#de%20Schipper--2021|de Schipper et al. (2021)]] ; [[#Elko--2021|Elko et al. (2021)]]

| Cross-Chapter Box SLR in Chapter 3, coastal development ( [[#3.6.3.1.1|Section 3.6.3.1.1]] )

|-
| Early-warning systems

| ''High confidence''

| Early-warning systems can support decision making, limit economic losses from extreme events and aid in the enterprise and development of adaptive management systems.

| Bindoff et al. (2019); [[#Collins--2019a|Collins et al. (2019a)]] ; [[#Winter--2020|Winter et al. (2020)]] ; [[#Neußner--2021|Neußner (2021)]]

| Coastal development ( [[#3.6.3.1.1|Section 3.6.3.1.1]] ), human health ( [[#3.6.3.1.5|Section 3.6.3.1.5]] )

|-
| Seasonal and dynamic forecasts

| ''High confidence''

| The proliferation of real-time and seasonal forecasts of temperature extremes, marine heatwaves, storm surges, harmful algal blooms and the distribution of living marine resources greatly contribute to adaptation through monitoring, early-warning systems, adaptive management and ecosystem-based management.

| [[#Payne--2017|Payne et al. (2017)]] ; [[#Hazen--2018|Hazen et al. (2018)]] ; [[#Fernández-Montblanc--2019|Fernández-Montblanc et al. (2019)]] ; [[#Holbrook--2020|Holbrook et al. (2020)]] ; [[#Winter--2020|Winter et al. (2020)]] ; Bever et al. (2021); [[#Davidson--2021|Davidson et al. (2021)]] ; [[#Spillman--2021|Spillman and Smith (2021)]]

| Fisheries and mariculture ( [[#3.6.3.1.2|Section 3.6.3.1.2]] ), marine protected areas (MPAs) ( [[#3.6.3.2|Section 3.6.3.2.1]] ), climate services ( [[#3.6.3.2|Section 3.6.3.2.4]] )

|-
| Monitoring systems

| ''Medium confidence''

| Monitoring systems that address climate-induced drivers, ecosystem impacts and social vulnerabilities in marine social–ecological systems are key for adaptation.

| [[#Nichols--2019|Nichols et al. (2019)]] ; [[#Claudet--2020a|Claudet et al. (2020a)]] ; [[#Wilson--2020a|Wilson et al. (2020a)]]

| MPAs ( [[#3.6.3.2|Section 3.6.3.2.1]] ), climate services ( [[#3.6.3.2|Section 3.6.3.2.4]] ), fisheries ( [[#3.6.3.1.2|Section 3.6.3.1.2]] )

|-
| Habitat development

| ''Low confidence''

| Accelerates the recovery of damaged ecosystems and promotes ecological or biological adaptation to future climate change.

| [[#Jones--2018a|Jones et al. (2018a)]] ; [[#Boström-Einarsson--2020|Boström-Einarsson et al. (2020)]] ; [[#Kleypas--2021|Kleypas et al. (2021)]]

| Restoration ( [[#3.6.3.2.2|Section 3.6.3.2.2]] )

|-
| Active restoration

| ''High confidence''

| Reintroduces species or augments existing populations, for example, propagating and transplanting heat-tolerant coral species.

| [[#Boström-Einarsson--2020|Boström-Einarsson et al. (2020)]] ; [[#Rinkevich--2021|Rinkevich (2021)]]

| Restoration (3.6.3.2.2)

|-
| Assisted evolution

| ''High confidence''

| Manipulates species’ genes to accelerate natural selection.

| [[#Bulleri--2018|Bulleri et al. (2018)]] ; [[#National%20Academies%20of%20Sciences--2019|National Academies of Sciences (2019)]] ; [[#Morris--2020c|Morris et al. (2020c)]]

| Restoration ( [[#3.6.3.2.2|Section 3.6.3.2.2]] )

|}

(a) Confidence is assessed in SM3.5.1. Feasibility and effectiveness are assessed in Figure 3.24.

<div id="3.6.2.3" class="h3-container"></div>

<span id="marine-and-coastal-nature-based-solutions"></span>
==== 3.6.2.3 Marine and Coastal Nature-Based Solutions ====

<div id="h3-37-siblings" class="h3-siblings"></div>

The ocean and coastal adaptation portfolio (Figure 3.23) also includes marine and coastal NbS (Table 3.30). NbS that contribute to climate adaptation, also known as ecosystem-based adaptations (EBA), are cross-cutting actions that harness ecosystem functions to restore, protect and sustainably manage marine ecosystems facing climate-change impacts, while also benefiting social systems and human security ( [[#Abelson--2015|Abelson et al., 2015]] ; [[#Barkdull--2019|Barkdull and Harris, 2019]] ) and supporting biodiversity ( ''high confidence'' ) (Annex II: Glossary; Cross-Chapter Box NATURAL in Chapter 2; [[#Seddon--2021|Seddon et al., 2021]] ). NbS are expected to contribute to global adaptation and mitigation goals ( ''high confidence'' ) ( [[#Beck--2018|Beck et al., 2018]] ; [[#Cooley--2019|Cooley et al., 2019]] ; [[#Hoegh-Guldberg--2019b|Hoegh-Guldberg et al., 2019b]] ; [[#Menéndez--2020|Menéndez et al., 2020]] ; [[#Morris--2020a|Morris et al., 2020a]] ) by protecting coastal environments from SLR and storms (Cross-Chapter Box SLR; [[#Reguero--2018|Reguero et al., 2018]] ), and by storing substantial quantities of carbon (Sections 3.4.2.5, 3.6.3.1.5; WGIII AR6 Chapter 7; [[#Howard--2017|Howard et al., 2017]] ; [[#Chow--2018|Chow, 2018]] ; [[#Smale--2018|Smale et al., 2018]] ; [[#Singh--2019b|Singh et al., 2019b]] ; [[#Soper--2019|Soper et al., 2019]] ). Marine NbS are cost-effective, can generate social, economic and cultural co-benefits, and can contribute to the conservation of biodiversity in the near- to mid-term ( ''high confidence'' ) ( [[#Secretariat%20of%20the%20Convention%20on%20Biological%20Diversity--2009|Secretariat of the Convention on Biological Diversity, 2009]] ; [[#Gattuso--2018|Gattuso et al., 2018]] ; [[#Barkdull--2019|Barkdull and Harris, 2019]] ; [[#McLeod--2019|McLeod et al., 2019]] ).

<div id="FAQ 3.4" class="h2-container"></div>

<span id="faq-3.4-which-industries-and-jobs-are-most-vulnerable-to-the-impacts-of-climate-change-in-the-oceans"></span>
=== FAQ 3.4 | Which industries and jobs are most vulnerable to the impacts of climate change in the oceans? ===

<div id="h2-32-siblings" class="h2-siblings"></div>

''The global ocean underpins human well-being through the provision of resources that directly and indirectly feed and employ many millions of people. In many regions, climate change is degrading ocean health and altering stocks of marine resources. Together with over-harvesting, climate change is threatening the future of the sustenance provided to Indigenous Peoples, the livelihoods of artisanal fisheries, and marine-based industries including tourism, shipping and transportation.''

The ocean is the lifeblood of the planet. In addition to regulating planetary cycles of carbon, water and heat, the ocean and its vast resources support human livelihoods, cultural practices, jobs and industries. The impacts of climate change on the ocean can influence human activities and employment by altering resource availability, spreading pathogens, flooding shorelines and degrading ocean ecosystems. Fishing and mariculture are highly exposed to change. The global ocean and inland waters together provide more than 3.3 billion people at least 20% of the protein they eat and provide livelihoods for 60 million people. Changes in the nutritional quality or abundance of food from the oceans could influence billions of people.

Substantial economic losses for fisheries resulting from recent climate-driven harmful algal blooms and marine pathogen outbreaks have been recorded in Asia, North America and South America. A 2016 event in Chile caused an estimated loss of 800 million USD in the farmed-salmon industry and led to regional government protests. The recent closure of the Dungeness crab and razor clam fishery in the USA due to a climate-driven algal bloom harmed 84% of surveyed residents from 16 California coastal communities. Fishers and service industries that support commercial and recreational fishing experienced the most substantial economic losses, and fishers were the least able to recover their losses. This same event also disrupted subsistence and recreational fishing for razor clams, important activities for Indigenous Peoples and local communities in the Pacific Northwest of the USA.

Other goods from the ocean, including non-food products like dietary supplements, food preservatives, pharmaceuticals, biofuels, sponges and cosmetic products, as well as luxury products like jewellery coral, cultured pearls and aquarium species, will change in abundance or quality due to climate change. For instance, ocean warming is endangering the ‘candlefish’ ooligan ( ''Thaleichthys pacificus'' ), whose oil is a traditional food source and medicine of Indigenous Peoples of the Pacific Northwest of North America. Declines in tourism and real estate values, associated with climate-driven harmful algal blooms, have also been recorded in the USA, France and England.

Small-scale fisheries livelihoods and jobs are the most vulnerable to climate-driven changes in marine resources and ecosystem services. The abundance and composition of their harvest depend on suitable environmental conditions and on IKLK developed over generations. Large-scale fisheries, though still vulnerable, are more able to adapt to climate change due to greater mobility and greater resources for changing technologies. These fisheries are already adapting by broadening catch diversity, increasing their mobility to follow shifting species, and changing gear, technology and strategies. Adaptation in large-scale fisheries, however, is at times constrained by regulations and governance challenges.

Jobs, industries and livelihoods which depend on particular species or are tied to the coast can also be at risk from climate change. Species-dependent livelihoods (e.g., a lobster fishery or oyster farm) are vulnerable due to a lack of substitutes if the fished species are declining, biodiversity is reduced, or mariculture is threatened by climate change or ocean acidification. Coastal activities and industries ranging from fishing (e.g., gleaning on a tidal flat) to tourism to shipping and transportation are also vulnerable to sea level rise and other climate-change impacts on the coastal environment. The ability of coastal systems to protect the shoreline will decline due to sea level rise and simultaneous degradation of nearshore systems, including coral reefs, kelp forests and coastal wetlands.

The vulnerability of communities to losses in marine ecosystem services varies within and among communities. Tourists seeking to replace lost cultural services can adapt by engaging in the activity elsewhere. But communities who depend on tourism for income or who have strong cultural identity linked to the ocean have a more difficult time. Furthermore, climate-change impacts exacerbate existing inequalities already experienced by some communities, including Indigenous Peoples, Pacific Island countries and territories and marginalised peoples, such as migrants and women in fisheries and mariculture. These inequities increase the risk to their fundamental human rights by disrupting livelihoods and food security, while leading to loss of social, economic and cultural rights. These maladaptive outcomes can be avoided by securing tenure and access rights to resources and territories for all people depending on the ocean, and by supporting decision-making processes that are just, participatory and equitable.

[[File:53e757327a32692fda6ba24464c408ff IPCC_AR6_WGII_Figure_3_FAQ_3_4.png]]

'''Figure FAQ3.4.1 |''' '''Illustration of vulnerable ocean and coastal groups, the climate-induced hazards they experience, and anticipated outcomes for human systems.'''

A key adaptation solution is improving access to credit and insurance in order to buffer against variability in resource access and abundance. Further actions that decrease social and institutional vulnerability are also important, such as inclusive decision-making processes, access to resources and land for Indigenous Peoples, and participatory approaches in management. For the fishing industry, international fisheries agreements and investing in sustainable mariculture and fisheries reforms is often recommended. Immediate adaptations to other challenges, such as harmful algal blooms, frequently include fishing-area closures; these can be informed by early-warning forecasts, public communications; and education. These types of adaptations are more effective when built on trusted relationships and effective coordination among involved parties, and are inclusive of the diversity of actors in a coastal community.

'''Table 3.30 |''' Assessment of marine and coastal nature-based solutions to reduce mid-term climate impacts in oceans and coastal ecosystems a

{| class="wikitable"
|-
! Solution

! Confidence in solution (mid-term potential)

! Contribution to adaptation

! Selected references

! Examples of implementation

|-
| Habitat restoration

| ''High confidence''

| Marine habitat restoration increases biodiversity and protects shorelines and coastal livelihoods from climate oceanic hazards.

| Colls et al. (2009); [[#Arkema--2017|Arkema et al. (2017)]] ; [[#Espeland--2018|Espeland and Kettenring (2018)]] ; [[#McLeod--2019|McLeod et al. (2019)]]

| Restoration ( [[#3.6.3.2.2|Section 3.6.3.2.2]] )

|-
| Marine protected areas (MPAs) and other effective area-based conservation measures (OECMs)

| ''High confidence''

| MPAs and MPA networks that are carefully designed to address climate change, strategically placed and well enforced, hold great potential to deliver adaptation outcomes. OECMs can confer climate resilience to dependent communities outside of MPAs.

| [[#3.4.3.3.4|Section 3.4.3.3.4]] ; [[#Queirós--2016|Queirós et al. (2016)]] ; [[#Roberts--2017|Roberts et al. (2017)]] ; [[#Maxwell--2020a|Maxwell et al. (2020a)]] ; [[#Arafeh-Dalmau--2021|Arafeh-Dalmau et al. (2021)]] ; [[#Gurney--2021|Gurney et al. (2021)]] ; [[#Sala--2021|Sala et al. (2021)]]

| Conservation ( [[#3.6.3.2|Section 3.6.3.2.1]] )

|-
| Conservation of climate refugia

| ''Medium confidence''

| Protecting areas that retain climate and biodiversity conditions for longer durations under climate change can increase the resilience of marine ecosystems to warming and marine heatwaves (MHWs), and facilitate marine species range shifts.

| [[#3.4.3.3.4|Section 3.4.3.3.4]] ; Cross-Chapter Box MOVING SPECIES in Chapter 5; [[#Rilov--2020|Rilov et al. (2020)]] ; [[#Wilson--2020a|Wilson et al. (2020a)]] ; [[#Arafeh-Dalmau--2021|Arafeh-Dalmau et al. (2021)]]

| Conservation ( [[#3.6.3.2|Section 3.6.3.2.1]] )

|-
| Transboundary marine spatial planning (MSP) and integrated coastal zone management (ICZM)

| ''Low confidence''

| Transboundary MSP and ICZM that incorporate climate-change impacts and adaptation in their design can support climate adaptation and foster international ocean cooperation.

| Rosendo et al. (2018); [[#Tittensor--2019|Tittensor et al. (2019)]] ; [[#Frazão%20Santos--2020|Frazão Santos et al. (2020)]] ; [[#Rilov--2020|Rilov et al. (2020)]] ; [[#Pinsky--2021|Pinsky et al. (2021)]]

| Tourism ( [[#3.6.3.1.3|Section 3.6.3.1.3]] ), conservation, ( [[#3.6.3.2|Section 3.6.3.2.1]] .)

|-
| Sustainable harvesting

| ''High confidence''

| Sustainable harvesting is a nature-based solution that contributes to adaptation by safeguarding the provision of marine food and cultural services while reducing the ecological vulnerability of marine ecosystems.

| [[#Gattuso--2018|Gattuso et al. (2018)]] ; [[#Burden--2019|Burden and Fujita (2019)]] ; [[#Duarte--2020|Duarte et al. (2020)]]

| Fisheries and mariculture ( [[#3.6.3.1.2|Section 3.6.3.1.2]] )

|-
| Climate-adaptive management

| ''High confidence''

| Incorporating climate-adaptive management allows climate knowledge and information available for the system to be iteratively updated in the management plan. It also facilitates consideration of species distribution shifts and other climate-change responses.

| Cross-Chapter Box MOVING SPECIES in Chapter 5; [[#Rilov--2019|Rilov et al. (2019)]] ; [[#Free--2020|Free et al. (2020)]] ; [[#Wilson--2020a|Wilson et al. (2020a)]] ; [[#Melbourne-Thomas--2021|Melbourne-Thomas et al. (2021)]]

| Fisheries and mariculture ( [[#3.6.3.1.2|Section 3.6.3.1.2]] ), conservation, ( [[#3.6.3.2|Section 3.6.3.2.1]] ), restoration ( [[#3.6.3.2.2|Section 3.6.3.2.2]] )

|-
| Ecosystem-based management (EbM)

| ''High confidence''

| EbM focuses on ecosystems. By incorporating many of the above tools, ecosystem-based adaptation benefits adaptation of marine ecosystems and supports provision of ecosystem services to people.

| Fernandino et al. (2018); [[#Lowerre-Barbieri--2019|Lowerre-Barbieri et al. (2019)]]

| Fisheries and mariculture ( [[#3.6.3.1.2|Section 3.6.3.1.2]] )

|}

(a) Confidence is assessed in SM3.5.1. Feasibility and effectiveness are assessed in Figure 3.24.

<div id="3.6.3" class="h2-container"></div>

<span id="implementation-and-effectiveness-of-adaptation-and-mitigation-measures"></span>
=== 3.6.3 Implementation and Effectiveness of Adaptation and Mitigation Measures ===

<div id="h2-22-siblings" class="h2-siblings"></div>

This section assesses implemented adaptations introduced in [[#3.6.2|Section 3.6.2]] for selected marine sectors ( [[#3.6.3.1|Section 3.6.3.1]] ) and ecosystems ( [[#3.6.3.2|Section 3.6.3.2]] ), using case studies to emphasise characteristics that enable or inhibit adaptation ( [[#3.6.3.3|Section 3.6.3.3]] ). The feasibility and effectiveness of these adaptations are assessed in Figure 3.24.

<div id="_idContainer115" class="Figure"></div>

[[File:249b35bf2d448ba466510a4f2992ed36 IPCC_AR6_WGII_Figure_3_024.png]]

'''Figure 3.24 |''' '''Assessment of feasibility and effectiveness of adaptation solutions for ocean and coastal ecosystems.''' Feasibility dimensions assessed include: technical and economic capacity to deliver and implement the solution; the institutional and geophysical capacity to implement a solution; and associated social and ecological implications that make a solution more feasible. The general feasibility level is obtained from assessment of the three dimensions together. Note that feasibility is assessed for marine and coastal ecosystems as a whole and not by ecosystem type or region. Feasibility dimensions and assessment are updated and adapted from [[#IPCC--2018|IPCC (2018)]] and [[#Singh--2020|Singh et al. (2020)]] . Effectiveness: ability of the adaptation solution to reduce climate-change mid-term risks. The main solutions are assessed per sector. (Underlying data are available in Table 3.SM.3.)

<div id="3.6.3.1" class="h3-container"></div>

<span id="degree-of-implementation-and-evidence-of-effectiveness-across-sectors"></span>
==== 3.6.3.1 Degree of Implementation and Evidence of Effectiveness Across Sectors ====

<div id="h3-38-siblings" class="h3-siblings"></div>

<div id="3.6.3.1.1" class="h4-container"></div>

<span id="coastal-community-development-and-settlement"></span>
===== 3.6.3.1.1 Coastal community development and settlement =====

<div id="h4-18-siblings" class="h4-siblings"></div>

Coastal adaptation often addresses the risk of flooding and erosion from SLR, changes in storm activity and degradation of coastal ecosystems and their services ( ''high confidence'' ) (Sections 3.4.2, 3.5; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ). Without coastal protection, people and property will be increasingly exposed to coastal flooding after 2050, especially under RCP8.5 (Cross-Chapter Box SLR in Chapter 3; [[#Bevacqua--2020|Bevacqua et al., 2020]] ; [[#Kirezci--2020|Kirezci et al., 2020]] ). This section assesses adaptation responses for coastal ecosystems, addressing loss of natural coastal protection (Sections 3.4.2.1, 3.4.2.4–3.4.2.6), and the need for relocation ( [[#3.6.2.1|Section 3.6.2.1.2]] ). Adaptation responses specific to SLR are assessed in detail in Cross-Chapter Box SLR in Chapter 3, while adaptation in coastal cities and settlements is assessed in Chapter 6.

Coastal conservation tends to involve cost-effective, low-impact actions that aim to support both adaptation and mitigation by conserving a wide array of ecosystem functions and services ( [[#Gattuso--2018|Gattuso et al., 2018]] ; [[#Gattuso--2021|Gattuso et al., 2021]] ), and that are achievable by nations with extensive coastlines or low-income status ( [[#Herr--2017|Herr et al., 2017]] ; [[#Taillardat--2018|Taillardat et al., 2018]] ). Where coastlines are undeveloped, the lowest-risk option is to avoid new development, but elsewhere, coastal conservation includes protection of key assets, accommodation of SLR, advancing defences seawards or upwards, or planned retreat from the coast (Cross-Chapter Box SLR in Chapter 3).

Hard-engineered structures like seawalls are generally more costly than nature-based adaptations ( ''high confidence'' ) ( [[#Hérivaux--2018|Hérivaux et al., 2018]] ; [[#Haasnoot--2019|Haasnoot et al., 2019]] ; [[#Nicholls--2019|Nicholls et al., 2019]] ; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ) and can lock communities into engineered responses in the future (Cross-Chapter Box SLR in Chapter 3), creating trade-offs with mitigation goals, which constitutes maladaptation ( [[#Nunn--2021|Nunn et al., 2021]] ) that carries ecological and cultural costs (Sections 3.4.2.4, 3.4.2.6, 3.5.6). As a result, there is ''high agreement'' on the importance of shifting from hard infrastructure to soft infrastructure for coastal defence ( [[#Toimil--2020|Toimil et al., 2020]] ; [[#Nunn--2021|Nunn et al., 2021]] ). The common remedy for beach erosion is beach nourishment ( [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ; [[#Pinto--2020|Pinto et al., 2020]] ; [[#Elko--2021|Elko et al., 2021]] ), which provides rapid results but poorly quantified trade-offs between efficacy, long-term cost, utility to beach users and ecological damage ( [[#de%20Schipper--2021|de Schipper et al., 2021]] ).

Since SROCC, coastal adaptation using NbS, like restoration of coastal vegetation, has advanced substantially ( [[#Cohen-Shacham--2019|Cohen-Shacham et al., 2019]] ; [[#Kuhl--2020|Kuhl et al., 2020]] ; [[#Kumar--2020|Kumar et al., 2020]] ; [[#Morris--2020a|Morris et al., 2020a]] ). Field and modelling studies confirm that wetland restoration and preservation are key actions to restore coastal protection and reduce community vulnerability to flooding ( ''very high confidenc'' e) (see also [[#3.6|Section 3.6]] ; Chapter 15; Cross-Chapter Box SLR in Chapter 3; [[#Jones--2020|Jones et al., 2020]] ; [[#Menéndez--2020|Menéndez et al., 2020]] ; [[#Van%20Coppenolle--2020|Van Coppenolle and Temmerman, 2020]] ), while maintaining coastal ecosystem services ( [[#3.5|Section 3.5]] ). Restoring coral reefs, oyster reefs and mangroves ( [[#3.6.2.1|Section 3.6.2.1]] ) and protecting macrophyte meadows dissipates wave energy ( [[#3.4.2.1|Section 3.4.2.1]] ; [[#Yates--2017|Yates et al., 2017]] ; [[#Beck--2018|Beck et al., 2018]] ; [[#Wiberg--2019|Wiberg et al., 2019]] ; [[#Menéndez--2020|Menéndez et al., 2020]] ), accretes sediment and elevate shorelines, which reduces exposure to waves and storm surges, and offsets erosional losses ( ''medium confidence'' ) ( [[#Kench--2017|Kench and Mann, 2017]] ; [[#Pomeroy--2018|Pomeroy et al., 2018]] ; [[#Dasgupta--2019|Dasgupta et al., 2019]] ; [[#James--2019|James et al., 2019]] ; [[#Morris--2019|Morris et al., 2019]] ; [[#David--2020|David and Schlurmann, 2020]] ; [[#Masselink--2020|Masselink et al., 2020]] ). However, irreversible regime shifts in ocean ecosystems due to SLR and extreme events, such as MHWs, can limit or compromise restoration in the long term ( ''high confidence'' ) ( [[#3.4.3.3.3|Section 3.4.3.3.3]] ; Cross-Chapter Box SLR in Chapter 3; [[#Marzloff--2016|Marzloff et al., 2016]] ; [[#Johnson--2017a|Johnson et al., 2017a]] ). Under all warming scenarios, coastal wetlands will be impacted by warming and MHWs (Sections 3.2.2.1, 3.2.4.5; Cross-Chapter Box 9.1 in WGI Chapter 9; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ), while also being pressed inland by RSLR ( [[#3.4.2.5|Section 3.4.2.5]] ; Cross-Chapter Box SLR in Chapter 3). Therefore, restoration and conservation are more successful when non-climate drivers are also minimised ( ''high confidence'' ) ( [[#Brodie--2020|Brodie et al., 2020]] ; [[#Duarte--2020|Duarte et al., 2020]] ; [[#Liu--2021|Liu et al., 2021]] ).

For highly exposed human settlements, migration is an adaptation option (e.g., for some island populations under extreme circumstances), but there are important uncertainties ( [[IPCC:Wg2:Chapter:Chapter-15#15.3.4.6|Section 15.3.4.6]] ), as international regimes develop around human rights, migration ( [[#Scobie--2019a|Scobie, 2019a]] ), displacement (George [[#Puthucherril--2012|Puthucherril, 2012]] ) and the implications for national sovereignty ( [[#Yamamoto--2014|Yamamoto and Esteban, 2014]] ) of disappearing land spaces caused by climate change. Colonial power dynamics can influence climate-change responses (Chapter 18), for example, when external funders favour migration over local desires to adapt in place to preserve national identity and sovereignty ( [[#Bordner--2020|Bordner et al., 2020]] ). Examples of relocation within livelihoods’ customary land show some successes ( [[IPCC:Wg2:Chapter:Chapter-15#15.3.4.6|Section 15.3.4.6]] ).

Evidence since SROCC (Section, 5.5.2.3.3; [[#Bindoff--2019a|Bindoff et al., 2019a]] ) continues to show that built infrastructure cannot address all of the adaptation challenges that coastal communities face. Coastal squeeze creates tensions between coastal development, armouring and habitat management (Sections 3.4.2.4–3.4.2.6). Managed realignment is the best option to reduce risks from SLR ( ''high confidence'' ) (Cross-Chapter Box SLR in Chapter 3) but requires transformative changes in coastal development and settlement (Felipe [[#Pérez--2021|Pérez and Tomaselli, 2021]] ; [[#Fitton--2021|Fitton et al., 2021]] ; [[#Mach--2021|Mach and Siders, 2021]] ; [[#Siders--2021|Siders et al., 2021]] ). Implementation of protective measures varies among nations and lack of financial resources limits the options available ( ''very high confidence'' ) (Cross-Chapter Box SLR in Chapter 3; [[#Hinkel--2018|Hinkel et al., 2018]] ; [[#Klöck--2019|Klöck and Nunn, 2019]] ).

<div id="3.6.3.1.2" class="h4-container"></div>

<span id="fisheries-and-mariculture"></span>
===== 3.6.3.1.2 Fisheries and mariculture =====

<div id="h4-19-siblings" class="h4-siblings"></div>

SROCC ( [[#Bindoff--2019a|Bindoff et al., 2019a]] ) assessed adaptation in fisheries and mariculture (marine aquaculture), and socioeconomically focused updates are provided in [[IPCC:Wg2:Chapter:Chapter-5#5.8.4|Section 5.8.4]] and Cross-Chapter Box MOVING SPECIES in Chapter 5. Here, we present a brief synthesis of how fisheries and mariculture adaptations interact with the natural environment, with further detail and supporting material in SM3.5.2.

Mobility allows fishing fleets and fishers to adapt to shifts in marine species distributions ( ''high agreement'' ) (Sections 3.4.3.1, 3.5.3; [[#Peck--2018|Peck and Pinnegar, 2018]] ; [[#Pinsky--2018|Pinsky et al., 2018]] ; [[#Frazão%20Santos--2020|Frazão Santos et al., 2020]] ) but with limits and unintended consequences ( [[#Pinsky--2012|Pinsky and Fogarty, 2012]] ; [[#Bell--2021|Bell et al., 2021]] ). Diversification of target species, harvest tactics and employment sectors, including transitions from fisheries to mariculture and ecotourism, allows some fishers to accommodate some impacts on their livelihoods ( [[#Miller--2018|Miller et al., 2018]] ; [[#Robinson--2020|Robinson et al., 2020]] ; [[#Gonzalez-Mon--2021|Gonzalez-Mon et al., 2021]] ). Technology and infrastructure adaptations can improve marine harvest efficiency, reduce risk and support resource management goals ( [[#Friedman--2020|Friedman et al., 2020]] ; [[#Bell--2021|Bell et al., 2021]] ; [[#Melbourne-Thomas--2021|Melbourne-Thomas et al., 2021]] ), but their ability to overcome climate-change impacts remains uncertain ( [[#Bell--2020|Bell et al., 2020]] ). Improving capacity to predict anomalous conditions in coastal and marine ecosystems ( [[#Jacox--2019|Jacox et al., 2019]] ; [[#Holbrook--2020|Holbrook et al., 2020]] ; [[#Jacox--2020|Jacox et al., 2020]] ), storm-driven flooding in reef-lined coasts ( [[#Scott--2020|Scott et al., 2020]] ; [[#Winter--2020|Winter et al., 2020]] ) and fisheries stocks ( [[#Payne--2017|Payne et al., 2017]] ; [[#Tommasi--2017|Tommasi et al., 2017]] ; [[#Muhling--2018|Muhling et al., 2018]] ) can improve forecasts of coastal and marine resources; these can enhance sustainability of wild-capture fisheries under climate change ( ''high confidence'' ) ( [[#Blanchard--2017|Blanchard et al., 2017]] ; [[#Tommasi--2017|Tommasi et al., 2017]] ; [[#Pinsky--2020a|Pinsky et al., 2020a]] ; [[#Bell--2021|Bell et al., 2021]] ). Limiting overexploitation is the central goal of fishery management, and it ''very likely'' benefits fisheries adaptation to climate change ( [[#Burden--2019|Burden and Fujita, 2019]] ; [[#Free--2019|Free et al., 2019]] ; [[#Sumaila--2020|Sumaila and Tai, 2020]] ). Conventional tools include catch and size limits, spatial management and adaptive management. Ecosystem-based fisheries management outperforms single-species management ( [[#Fulton--2019|Fulton et al., 2019]] ), is widely legislated ( [[#Bryndum-Buchholz--2021|Bryndum-Buchholz et al., 2021]] ) and can reduce climate impacts in fisheries in the near-term, especially under low-emission scenarios ( [[#Karp--2019|Karp et al., 2019]] ; [[#Holsman--2020|Holsman et al., 2020]] ). Transboundary agreements on shifting fisheries will reduce the risk of overharvesting ( ''medium confidence'' ) ( [[#Gaines--2018|Gaines et al., 2018]] ). Permits tradable across political boundaries could also address this challenge, but ''limited evidence'' is available regarding their efficacy (Cross-Chapter Box MOVING SPECIES in Chapter 5; [[#Pinsky--2018|Pinsky et al., 2018]] ). Climate-smart conservation ( [[#3.6.3|Section 3.6.3]] 2.1) under the negotiations on areas beyond national jurisdiction (ABNJ) ( [[#Pinsky--2018|Pinsky et al., 2018]] ; [[#Tittensor--2019|Tittensor et al., 2019]] ; [[#Frazão%20Santos--2020|Frazão Santos et al., 2020]] ), and in the Convention on Biological Diversity (CBD) areas designed as other effective area-based conservation measures (OECMs) ( [[#Tittensor--2019|Tittensor et al., 2019]] ), provide further benefits. Despite the potential for adaptive management to achieve sustainable fisheries, outcomes will ''very likely'' be inequitable ( [[#Gaines--2018|Gaines et al., 2018]] ; [[#Lam--2020|Lam et al., 2020]] ), with lower-income countries suffering the greater biomass and economic losses, increasing inequalities, especially under higher-emission scenarios ( ''high confidence'' ) ( [[#Boyce--2020|Boyce et al., 2020]] ). Flexible and polycentric governance approaches have facilitated some short-term successes in achieving equitable, sustainable fisheries practices, but these may be challenging to implement where other governance systems, especially hierarchical systems, are well established ( [[#Cvitanovic--2018|Cvitanovic et al., 2018]] ; [[#Bell--2020|Bell et al., 2020]] ).

<div id="3.6.3.1.3" class="h4-container"></div>

<span id="tourism"></span>
===== 3.6.3.1.3 Tourism =====

<div id="h4-20-siblings" class="h4-siblings"></div>

Coastal areas, coastal infrastructure and beaches, sustaining tourism that contributes significantly to local economies ( [[#James--2019|James et al., 2019]] ; [[#Ruiz-Ramírez--2019|Ruiz-Ramírez et al., 2019]] ), are under threat from development, SLR and increased wave energy during storms ( ''high confidence'' ) (Sections 3.4.2.4–3.4.2.6, 3.5.6, SM3.3.1; [[#Lithgow--2019|Lithgow et al., 2019]] ; [[#Ruiz-Ramírez--2019|Ruiz-Ramírez et al., 2019]] ). Engineered solutions, such as seawalls and revetments, have traditionally been used to address coastal erosion ( [[#3.6.3.1.1|Section 3.6.3.1.1]] ), but soft infrastructure approaches, including beach nourishment, submerged breakwaters and groins, and NbS ( [[#3.6.2.1|Section 3.6.2.1]] ), are becoming more common, partly due to demand from the tourism industry ( ''medium confidence'' ) ( [[#Pranzini--2018|Pranzini, 2018]] ; [[#Pranzini--2018|Pranzini et al., 2018]] ).

Elsewhere, interactions between tourism and climate impacts worsen outcomes for coastal and ocean environments ( [[#3.6.3.1.4|Section 3.6.3.1.4]] ). Climate change is opening up new cruise-ship routes in the Arctic ( [[#Sun--2018|Sun et al., 2018]] ), increasing the number of visitors and associated stressors, such as litter, to previously undisturbed areas ( [[#Anfuso--2020|Anfuso et al., 2020]] ; [[#Hovelsrud--2020|Hovelsrud et al., 2020]] ; [[#Suaria--2020|Suaria et al., 2020]] ). Risk reduction for cruise-ship tourism includes disaster response management, improved mapping and passenger codes of conduct ensuring social, cultural and ecological sustainability ( [[#Stewart--2015|Stewart et al., 2015]] ; [[#Dawson--2016|Dawson et al., 2016]] ).

Marine ecotourism, integrating conservation, education and provision of benefits to local communities ( [[#Donohoe--2006|Donohoe and Needham, 2006]] ) can provide significant economic benefits ( [[#Wabnitz--2019|Wabnitz, 2019]] ) and is among the most common livelihood alternatives to support both marine conservation and climate-change adaptation ( [[#Kutzner--2019|Kutzner, 2019]] ; [[#Pham--2020|Pham, 2020]] ; [[#Prasetyo--2020|Prasetyo et al., 2020]] ). Ecotourism can enhance social and political will for marine conservation ( [[#Cisneros-Montemayor--2014|Cisneros-Montemayor and Sumaila, 2014]] ) and facilitates integration of local and Indigenous Peoples in employment, ownership and industry governance. The community of Cabo Pulmo, Mexico, self-imposed an MPA and replaced fishing with ecotourism, which now generates millions of USD yr –1 , sustains locally owned and operated tour companies and has increased some fish populations tenfold ( [[#Knowlton--2020|Knowlton, 2020]] ). In Misool, Indonesia, local ecotourism incorporates IK by including local communities’ preferences and sustainable resource use ( [[#Prasetyo--2020|Prasetyo et al., 2020]] ).

Unintended consequences of ecotourism, such as detrimental ecological impacts on reefs ( [[#Giglio--2020|Giglio et al., 2020]] ), sharks, marine birds ( [[#Monti--2018|Monti et al., 2018]] ) and whales ( [[#Higham--2016|Higham et al., 2016]] ; [[#Barra--2020|Barra et al., 2020]] ; [[#Hoarau--2020|Hoarau et al., 2020]] ), can be minimised by relying on evidence-based management of associated activities ( [[#Blumstein--2017|Blumstein et al., 2017]] ). Public perception of climate-change connections to tourism can create obstacles ( [[#Meynecke--2017|Meynecke et al., 2017]] ; [[#Atzori--2018|Atzori et al., 2018]] ) such as deterring long-term investment in SIDS tourism initiatives ( [[#Santos-Lacueva--2017|Santos-Lacueva et al., 2017]] ), or benefits like inclining tourists to participate in conservation projects ( [[#Curnock--2019|Curnock et al., 2019]] ; [[#Miller--2020b|Miller et al., 2020b]] ; [[#Ziegler--2021|Ziegler et al., 2021]] ). Social and cultural networks may decrease climate vulnerability, as with Indigenous tourism operators in SIDS ( [[#Parsons--2018|Parsons et al., 2018]] ). Tourism-based adaptation can also be improved by equitable access to resources as well as recognition and inclusion of all stakeholders during policy planning and implementation. The principles of marine spatial planning ( [[#Papageorgiou--2016|Papageorgiou, 2016]] ) provide for effectively incorporating stakeholders and could inform development of activities to assess climate-associated risks (e.g., [[#Tzoraki--2018|Tzoraki et al., 2018]] ; [[#Loehr--2020|Loehr, 2020]] ). The recent decrease in global tourism due to the COVID-19 pandemic may offer opportunities to transform existing practices to more sustainable approaches (Cross-Chapter Box COVID in Chapter 7; [[#Gössling--2021|Gössling et al., 2021]] ).

<div id="3.6.3.1.4" class="h4-container"></div>

<span id="maritime-transport"></span>
===== 3.6.3.1.4 Maritime transport =====

<div id="h4-21-siblings" class="h4-siblings"></div>

Increased maritime transport and cruise-ship tourism in the Arctic are already impacting local and Indigenous Peoples, revealing conflicts over the uses of the ocean and the governance needed to support local people and a sustainable blue economy ( ''high confidence'' ) ( [[#Debortoli--2019|Debortoli et al., 2019]] ; [[#Palma--2019|Palma et al., 2019]] ; [[#Berman--2020|Berman et al., 2020]] ; [[#Dundas--2020|Dundas et al., 2020]] ). While shipping and its associated environmental impacts are projected to grow ( [[#Palma--2019|Palma et al., 2019]] ; [[#Dawson--2020|Dawson et al., 2020]] ), adaptation efforts are only at the planning stage ( [[#Debortoli--2019|Debortoli et al., 2019]] ). Increased Arctic traffic due to ice loss can benefit trade, transportation and tourism ( ''medium confidence'' ), but will also affect Arctic marine ecosystems and livelihoods ( ''high confidence'' ) ( [[#Palma--2019|Palma et al., 2019]] ; [[#Dawson--2020|Dawson et al., 2020]] ). Increasing search-and-rescue activities ( [[#Ford--2019|Ford and Clark, 2019]] ) reveal capacity gaps to support future demands ( [[#Ford--2019|Ford and Clark, 2019]] ; [[#Palma--2019|Palma et al., 2019]] ). The Low-Impact Shipping Corridors initiative has been developed as an adaptation strategy in the Arctic, although with limited inclusion of IKLK ( [[#Dawson--2020|Dawson et al., 2020]] ).

Relative SLR and the increased frequency and severity of storms are already affecting port activity, infrastructure and supply chains, sometimes disrupting trade and transport ( [[#Monios--2020|Monios and Wilmsmeier, 2020]] ), but these hazards are not systematically incorporated into adaptation planning ( ''medium evidence'' ) ( [[#Monios--2020|Monios and Wilmsmeier, 2020]] ; [[#O’Keeffe--2020|O’Keeffe et al., 2020]] ). Climate-change impacts that increase food insecurity, income loss and poverty can exacerbate maritime criminal activity, including illegal fishing, drug trafficking or piracy ( ''medium evidence'' ) ( [[#Germond--2019|Germond and Mazaris, 2019]] ). A transformational adaptation approach to address climate impacts on maritime activities and increase security ( [[#Germond--2019|Germond and Mazaris, 2019]] ) would relocate ports, change centres of demand, reduce shipping distances or shorten supply chains ( ''medium agreement'' ) ( [[#Walsh--2019|Walsh et al., 2019]] ; [[#Monios--2020|Monios and Wilmsmeier, 2020]] ) as well as decrease marginalisation of vulnerable groups, develop polycentric governance systems and eliminate maladaptive environmental policies and resource loss ( [[#Belhabib--2020|Belhabib et al., 2020]] ; [[#O’Keeffe--2020|O’Keeffe et al., 2020]] ).

<div id="3.6.3.1.5" class="h4-container"></div>

<span id="human-health"></span>
===== 3.6.3.1.5 Human health =====

<div id="h4-22-siblings" class="h4-siblings"></div>

Health-focused adaptations to climate-driven changes in ocean and coastal water quality ( [[#3.5.5.3|Section 3.5.5.3]] ) leverage mainly technology and infrastructure ( [[#3.6.2.2|Section 3.6.2.2]] ) to improve water-quality monitoring and forecasting to inform socio-institutional adaptation ( [[#3.6.2.1|Section 3.6.2.1]] ) and NbS ( [[#3.6.2.3|Section 3.6.2.3]] ). Seafood quality and safety are decreasing due to climate-driven increases in marine-borne diseases (Cross-Chapter Box ILLNESS in Chapter 2), toxic HABs or toxin bioaccumulation ( ''high agreement'' ) ( [[#Karagas--2012|Karagas et al., 2012]] ; [[#Krabbenhoft--2013|Krabbenhoft and Sunderland, 2013]] ; [[#Rafaj--2013|Rafaj et al., 2013]] ; [[#Curtis--2019|Curtis et al., 2019]] ; [[#Schartup--2019|Schartup et al., 2019]] ; [[#Thackray--2019|Thackray and Sunderland, 2019]] ). Future exposure to seafood-borne contaminants also depends partly on consumers’ seafood preferences ( [[#Elsayed--2020|Elsayed et al., 2020]] ) and seafood supply ( [[#Sunderland--2018|Sunderland et al., 2018]] ). Reducing this risk by decreasing seafood consumption increases the risk of eating less nutritious foods, and loss of cultural practices (Chapter 5; Cross-Chapter Box MOVING SPECIES in Chapter 5; [[#Donatuto--2011|Donatuto et al., 2011]] ; [[#Bindoff--2019a|Bindoff et al., 2019a]] ). Models incorporating high-resolution satellite images, field survey data, meteorological observations and historical records can provide early-warning forecasts of HABs or conditions that favour microbial pathogen outbreaks (Cross-Chapter Box ILLNESS in Chapter 2; [[#Semenza--2017|Semenza et al., 2017]] ; [[#Franks--2018|Franks, 2018]] ; [[#Hattenrath-Lehmann--2018|Hattenrath-Lehmann et al., 2018]] ; [[#Borbor-Cordova--2019|Borbor-Cordova et al., 2019]] ; [[#Davis--2019|Davis et al., 2019]] ; [[#Campbell--2020a|Campbell et al., 2020a]] ; [[#Davidson--2021|Davidson et al., 2021]] ). Forecasts facilitate preventive public health measures ( [[#World%20Health%20Organisation%20and%20United%20Nations%20Children’s%20Fund--2017|World Health Organisation and United Nations Children’s Fund, 2017]] ), or seafood harvest guidance ( [[#Maguire--2016|Maguire et al., 2016]] ; [[#Leadbetter--2018|Leadbetter et al., 2018]] ; [[#Anderson--2019|Anderson et al., 2019]] ; [[#Bolin--2021|Bolin et al., 2021]] ), reducing risks of disease outbreaks, waste and contaminated seafood entering the market ( ''medium confidence'' ) (Cross-Chapter Box ILLNESS in Chapter 2; [[#Nichols--2018|Nichols et al., 2018]] ). Monitoring of water quality and seafood safety (Cross-Chapter Box ILLNESS in Chapter 2), paired with effective public communication and education ( [[#Ekstrom--2020|Ekstrom et al., 2020]] ), inform individual and local adaptations, including use of (a) personal protective equipment, (b) seafood selection and preparation ( [[#Elsayed--2020|Elsayed et al., 2020]] ; [[#Froelich--2020|Froelich and Daines, 2020]] ; [[#Fielding--2021|Fielding et al., 2021]] ), (c) income diversification ( [[#3.6.2.1|Section 3.6.2.1]] ; [[#Moore--2020b|Moore et al., 2020b]] ), (d) public education ( [[#Borbor-Cordova--2019|Borbor-Cordova et al., 2019]] ) or (e) community-level actions to decrease risk from coastal aquifer and soil salinisation ( [[#Slama--2020|Slama et al., 2020]] ; [[#Mastrocicco--2021|Mastrocicco and Colombani, 2021]] ), HAB toxins ( [[#Ekstrom--2020|Ekstrom et al., 2020]] ) and other contaminants (e.g., methylmercury, metals, persistent organic pollutants) in seafood ( [[#Chan--2021|Chan et al., 2021]] ). A full assessment of climate-change impacts on human health is found in [[IPCC:Wg2:Chapter:Chapter-7|Chapter 7]] and Cross-Chapter Box ILLNESS in Chapter 2.

<div id="3.6.3.2" class="h3-container"></div>

<span id="cross-cutting-solutions-for-coastal-and-ocean-ecosystems"></span>
==== 3.6.3.2 Cross-Cutting Solutions for Coastal and Ocean Ecosystems ====

<div id="h3-39-siblings" class="h3-siblings"></div>

SROCC concluded that protection, restoration and pollution reduction can support ocean and coastal ecosystems ( ''high confidence'' ), and that EbA lowers climate risks locally and provides multiple societal benefits ( ''high confidence'' ) ( [[#IPCC--2019c|IPCC, 2019c]] ). This section updates the assessment of the effectiveness of these strategies for addressing climate impacts.

<div id="3.6.3.2.1 " class="h4-container"></div>

<span id="area-based-protection-mpas-for-adapting-to-climate-change"></span>
===== 3.6.3.2.1 Area-based protection: MPAs for adapting to climate change =====

<div id="h4-23-siblings" class="h4-siblings"></div>

Marine protected areas are the most widely implemented area-based management approach ( [[#3.6.2.3|Section 3.6.2.3.2]] ), commonly intended to conserve, preserve or restore biodiversity and habitats, protect species or manage resources (especially fisheries) ( [[#National%20Research%20Council--2001|National Research Council, 2001]] ). By August 2021, 7.74% of the ocean was protected (in both MPAs and OECMs) ( [[#UNEP-WCMC%20and%20IUCN--2021|UNEP-WCMC and IUCN, 2021]] ), primarily within nations’ exclusive economic zones (EEZs). These MPAs support adaptation by sustaining nearshore ecosystems that provide natural erosion barriers (Sections 3.4.2.1–3.4.2.5; Cross-Chapter Box SLR in Chapter 3), ecosystem function ( [[#Cheng--2019|Cheng et al., 2019]] ), habitat, natural filtration, carbon storage, livelihoods and cultural opportunities (Sections 3.5.5, 3.5.6; [[#Erskine--2021|Erskine et al., 2021]] ), and help ecosystems and livelihoods recover after extreme events ( [[#Roberts--2017|Roberts et al., 2017]] ; [[#Aalto--2019|Aalto et al., 2019]] ; [[#Wilson--2020a|Wilson et al., 2020a]] ). However, in 2021 only 2.7% of the ocean was in fully or highly protected MPAs ( [[#Marine%20Conservation%20Institute--2021|Marine Conservation Institute, 2021]] ), the hard-to-achieve states that most effectively rebuild biomass and fish community structure ( [[#Sala--2017|Sala and Giakoumi, 2017]] ; [[#Bergseth--2018|Bergseth, 2018]] ; [[#Zupan--2018|Zupan et al., 2018]] ; [[#Ohayon--2021|Ohayon et al., 2021]] ). Only 1.18% of ABNJ is protected ( [[#UNEP-WCMC%20and%20IUCN--2021|UNEP-WCMC and IUCN, 2021]] ), mostly due to governance limitations ( [[#O’Leary--2017|O’Leary and Roberts, 2017]] ; [[#Vijayaraghavan--2021|Vijayaraghavan, 2021]] ), but calls to protect more ABNJ emphasise the need to protect the habitats of long-range pelagic fish and marine mammals, maintain the ocean’s regulating functions and minimise impacts from uses such as maritime shipping or deep-sea mining (Table 3.30).

Marine protected areas are theorised to facilitate ecological climate adaptation and contribute to SDG14 (Life Below Water) (Table 3.30; Figure 3.26; [[#Bates--2014|Bates et al., 2014]] ; [[#Lubchenco--2015|Lubchenco and Grorud-Colvert, 2015]] ; [[#Gattuso--2018|Gattuso et al., 2018]] ) because they alleviate non-climate drivers and promote biodiversity (i.e., ‘managed resilience hypothesis’) ( [[#Bruno--2019|Bruno et al., 2019]] ; [[#Maestro--2019|Maestro et al., 2019]] ; [[#Cinner--2020|Cinner et al., 2020]] ). Current MPAs offer conservation benefits such as increases in biomass and diversity of habitats, populations and communities ( ''high confidence'' ) ( [[#Pendleton--2018|Pendleton et al., 2018]] ; [[#Bates--2019|Bates et al., 2019]] ; [[#Stevenson--2020|Stevenson et al., 2020]] ; [[#Lenihan--2021|Lenihan et al., 2021]] ; [[#Ohayon--2021|Ohayon et al., 2021]] ), and these benefits may last after some (possibly climate-enhanced) disturbances (e.g., tropical cyclones) ( [[#McClure--2020|McClure et al., 2020]] ). But current MPAs do not provide resilience against observed warming and heatwaves in tropical-to-temperate ecosystems ( ''medium confidence'' ) ( [[#Bates--2019|Bates et al., 2019]] ; [[#Bruno--2019|Bruno et al., 2019]] ; [[#Freedman--2020|Freedman et al., 2020]] ; [[#Graham--2020|Graham et al., 2020]] ; [[#Rilov--2020|Rilov et al., 2020]] ). There is ''robust evidence'' that processes around MPA design and implementation strongly influence whether outcomes are beneficial or harmful for adjacent human communities (Mc [[#Neill--2018|Neill et al., 2018]] ; [[#Zupan--2018|Zupan et al., 2018]] ; [[#Ban--2019|Ban et al., 2019]] ).

Current placement and extent of MPAs will not provide substantial protections against projected climate change past 2050 ( ''high confidence'' ), as the placement of MPAs has been driven more often by political expediency (e.g., [[#Leenhardt--2013|Leenhardt et al., 2013]] ) than by managing key drivers of biodiversity loss ( [[#Cockerell--2020|Cockerell et al., 2020]] ; [[#Stevenson--2020|Stevenson et al., 2020]] ) or climate-induced drivers ( [[#Bruno--2018|Bruno et al., 2018]] ). Only 3.5% of the area currently protected will provide refuges from both SST and deoxygenation by 2050 under both RCP4.5 and RCP8.5 ( [[#Bruno--2018|Bruno et al., 2018]] ), and MPAs are more exposed to climate change under RCP8.5 than non-MPAs ( [[#3.4.3.3.4|Section 3.4.3.3.4]] ; Figure 3.20d). Community thermal tolerances will be exceeded by 2050 in the tropics and by 2150 for many higher-latitude MPAs ( [[#Bruno--2018|Bruno et al., 2018]] ). Most MPA design has focused on the surface ocean, but MPAs are assumed to protect the entire water column and benthos. Climate-induced drivers ( [[#3.2|Section 3.2]] ) throughout the water column and rapidly accelerating climate velocities at depths below 200 m ( [[#Johnson--2018|Johnson et al., 2018]] ; [[#Brito-Morales--2020|Brito-Morales et al., 2020]] ) are projected to affect virtually all North Atlantic deep-water and open-ocean area-based management zones in the next 20–50 years ( [[#Johnson--2018|Johnson et al., 2018]] ), and the conservation goals of benthic MPAs in the North Sea are not expected to be fulfilled ( [[#Weinert--2021|Weinert et al., 2021]] ). Heightened risk of non-indigenous species immigration from vessel traffic plus climate change further endangers MPA success ( [[#Iacarella--2020|Iacarella et al., 2020]] ), a particular concern in the Mediterranean ( [[#D’Amen--2020|D’Amen and Azzurro, 2020]] ; [[#Mannino--2021|Mannino and Balistreri, 2021]] ), where the current MPA network is already highly vulnerable to climate change ( [[#Kyprioti--2021|Kyprioti et al., 2021]] ). This new evidence supports SROCC’s ''high confidence'' assessment that present governance arrangements, including MPAs, are too fragmented to provide integrated responses to the increasing and cascading risks from climate change in the ocean (SROCC SPMC1.2; [[#IPCC--2019c|IPCC, 2019c]] ).

Strategic conservation planning can yield future MPA networks substantially more ready for climate change (e.g., [[#3.6.3.1.5|Section 3.6.3.1.5]] ; SROCC SPM C2.1; [[#IPCC--2019c|IPCC, 2019c]] ; [[#Frazão%20Santos--2020|Frazão Santos et al., 2020]] ; [[#Rassweiler--2020|Rassweiler et al., 2020]] ). Global protection is increasing ( [[#Worm--2017|Worm, 2017]] ; [[#Claudet--2020b|Claudet et al., 2020b]] ) as nations pursue international targets (e.g., SDG14, Life Below Water aimed to conserve 10% of the ocean by 2020), and the UN CBD proposes to protect 30% by 2030 ( [[#3.6.4|Section 3.6.4]] ; SM3.5.3; [[#CBD--2020|CBD, 2020]] ). A growing body of evidence ( [[#Tittensor--2019|Tittensor et al., 2019]] ; [[#Zhao--2020a|Zhao et al., 2020a]] ; [[#Pörtner--2021b|Pörtner et al., 2021b]] ; [[#Sala--2021|Sala et al., 2021]] ) underscores the urgent need to pursue biodiversity, ecosystem-service provision and climate-adaptation goals simultaneously, while acknowledging inherent trade-offs ( [[#Claudet--2020a|Claudet et al., 2020a]] ; [[#Sala--2021|Sala et al., 2021]] ). Frameworks to create ‘climate-smart’ MPAs ( [[#Tittensor--2019|Tittensor et al., 2019]] ) generally include: (a) defining conservation goals that embrace resource vulnerabilities and co-occurring hazards; (b) carefully selecting adaptation strategies that include IKLK while respecting Indigenous rights and accommodating human behaviour ( [[#Kikiloi--2017|Kikiloi et al., 2017]] ; [[#Thomas--2018|Thomas, 2018]] ; [[#Yates--2019|Yates et al., 2019]] ; [[#Failler--2020|Failler et al., 2020]] ; [[#Wilson--2020a|Wilson et al., 2020a]] ; [[#Croke--2021|Croke, 2021]] ; Reimer et al., 2021; [[#Vijayaraghavan--2021|Vijayaraghavan, 2021]] ); (c) developing protection that is appropriate for all ocean depths ( [[#Brito-Morales--2018|Brito-Morales et al., 2018]] ; [[#Frazão%20Santos--2020|Frazão Santos et al., 2020]] ; [[#Wilson--2020a|Wilson et al., 2020a]] ), especially considering climate velocity ( [[#Arafeh-Dalmau--2021|Arafeh-Dalmau et al., 2021]] ); (d) using dynamic national and international management tools to accommodate extreme events or species distribution shifts ( [[#Gaines--2018|Gaines et al., 2018]] ; [[#Pinsky--2018|Pinsky et al., 2018]] ; [[#Bindoff--2019a|Bindoff et al., 2019a]] ; [[#Scheffers--2019|Scheffers and Pecl, 2019]] ; [[#Tittensor--2019|Tittensor et al., 2019]] ; [[#Cashion--2020|Cashion et al., 2020]] ; [[#Crespo--2020|Crespo et al., 2020]] ; [[#Frazão%20Santos--2020|Frazão Santos et al., 2020]] ; [[#Maxwell--2020b|Maxwell et al., 2020b]] ), which could build on dynamic regulations already in place for fishing or ship strikes ( [[#Maxwell--2020b|Maxwell et al., 2020b]] ); and (e) seeking to increase connectivity ( [[#Wilson--2020a|Wilson et al., 2020a]] ), using genomic or multi-species model insights ( [[#Xuereb--2020|Xuereb et al., 2020]] ; [[#Friesen--2021|Friesen et al., 2021]] ; [[#Lima--2021|Lima et al., 2021]] ).

There is growing international support for a 30% conservation target for 2030 ( [[#Gurney--2021|Gurney et al., 2021]] ), which will need efforts beyond protected areas. For example, OECMs recognise management interventions that sustain biodiversity, irrespective of their main objective ( [[#Maxwell--2020b|Maxwell et al., 2020b]] ; [[#Gurney--2021|Gurney et al., 2021]] ). There is ''high agreement'' on the potential of OECMs to contribute to conservation and equity, for example, by recognising Indigenous territories as OECMs ( [[#Maxwell--2020b|Maxwell et al., 2020b]] ; [[#Gurney--2021|Gurney et al., 2021]] ); however, the capacity of these conservation tools to provide adaptation outcomes remains unexplored.

In summary, MPAs and other marine spatial-planning tools have great potential to address climate-change mitigation and adaptation in ocean and coastal ecosystems, if they are designed and implemented in a coordinated way that takes into account ecosystem vulnerability and responses to projected climate conditions, considers existing and future ecosystem uses and non-climate drivers, and supports effective governance ( ''high confidence'' ).

<div id="3.6.3.2.2" class="h4-container"></div>

<span id="ecological-restoration-interventions-and-their-limitations"></span>
===== 3.6.3.2.2 Ecological restoration, interventions and their limitations =====

<div id="h4-24-siblings" class="h4-siblings"></div>

Restoration of degraded ecosystems is a common NbS increasingly deployed at local scales in response to climate change (Cross-Chapter Box NATURAL in Chapter 2; [[#Duarte--2020|Duarte et al., 2020]] ; [[#Bertolini--2021|Bertolini and da Mosto, 2021]] ; [[#Braun%20de%20Torrez--2021|Braun de Torrez et al., 2021]] ). Despite covering limited areas and having uncertain efficacy under future climate change ( [[#Gordon--2020|Gordon et al., 2020]] ), these actions have successfully restored marine populations and ecosystems at regional to global scales ( [[#Duarte--2020|Duarte et al., 2020]] ), and enhanced livelihoods and the well-being of coastal peoples as well as the biodiversity and resilience of ecological communities ( [[#Silver--2019|Silver et al., 2019]] ; [[#Gordon--2020|Gordon et al., 2020]] ; [[#Braun%20de%20Torrez--2021|Braun de Torrez et al., 2021]] ). Technology-based approaches, such as active restoration, assisted evolution and ecological forecasting, can aid in moving beyond restoring ecosystems ( [[#3.6.2.3|Section 3.6.2.3]] ) towards enhancing resilience, reviving biodiversity and guarding against loss of foundational, ornamental or iconic species ( [[#Bulleri--2018|Bulleri et al., 2018]] ; [[#Collins--2019a|Collins et al., 2019a]] ; [[#da%20Silva--2019|da Silva et al., 2019]] ; [[#National%20Academies%20of%20Sciences--2019|National Academies of Sciences, 2019]] ; [[#Boström-Einarsson--2020|Boström-Einarsson et al., 2020]] ; [[#Fredriksen--2020|Fredriksen et al., 2020]] ; [[#Morris--2020c|Morris et al., 2020c]] ; [[#Kleypas--2021|Kleypas et al., 2021]] ).

Local restoration projects often target vegetated ecosystems like mangroves, seagrasses and salt marshes that are valued and used by coastal communities ( [[#Veettil--2019|Veettil et al., 2019]] ; [[#Duarte--2020|Duarte et al., 2020]] ; [[#Wu--2020a|Wu et al., 2020a]] ; [[#Bertolini--2021|Bertolini and da Mosto, 2021]] ). Detail on mangroves and corals as EbA and protection/restoration hotspots is provided in SM3.8. Common and effective actions ( [[#Sasmito--2019|Sasmito et al., 2019]] ; [[#Duarte--2020|Duarte et al., 2020]] ; [[#Oreska--2020|Oreska et al., 2020]] ) include securing accommodation space (Sections 3.4.2.4–3.4.2.5), restoring hydrological ( [[#Kroeger--2017|Kroeger et al., 2017]] ; [[#Al-Haj--2020|Al-Haj and Fulweiler, 2020]] ) and sediment dynamics; managing harvesting (particularly in mangroves); reducing pollution (especially in seagrasses) ( [[#de%20los%20Santos--2019|de los Santos et al., 2019]] ); and replanting appropriate species in suitable environmental settings ( [[#Wodehouse--2019|Wodehouse and Rayment, 2019]] ; [[#Friess--2020a|Friess et al., 2020a]] ). Although efficacy is context dependent ( [[#Zeng--2020|Zeng et al., 2020]] ; [[#Krause-Jensen--2021|Krause-Jensen et al., 2021]] ) and implementation is most often local ( [[#Alongi--2018a|Alongi, 2018a]] ), such projects facilitate tangible community engagement in climate action. Moreover, because these ecosystems sequester disproportionate amounts of carbon (blue carbon) (Annex II: Glossary; see Box 3.4), restoration supports climate-change mitigation ( [[#Lovelock--2020|Lovelock and Reef, 2020]] ; [[#Gattuso--2021|Gattuso et al., 2021]] ). Yet, constraints remain. For instance, Southeast Asia has 1.21 million km 2 of terrestrial, freshwater and mangrove area biophysically suitable for reforestation, which could mitigate 3.43 ± 1.29 Pg CO 2 e yr −1 through 2030; however, reforestation is only feasible in a small fraction of this area (0.3–18%) given financial, land-use and operational constraints ( [[#Zeng--2020|Zeng et al., 2020]] ). Nevertheless, the multiple benefits offered by ecosystem restoration will ''likely'' outweigh competing costs and increase its relevance as part of adaptation-strategy portfolios ( [[#Silver--2019|Silver et al., 2019]] ; [[#Wedding--2021|Wedding et al., 2021]] ), national carbon-accounting systems and nationally determined contributions by parties to the Paris Agreement ( [[#Friess--2020a|Friess et al., 2020a]] ; [[#Wu--2020a|Wu et al., 2020a]] ).

Restoration efficacy of coral reefs, kelp forests and other habitat-forming coastal ecosystems (Sections 3.4.2.2–3.4.2.6) are jeopardised by the near-term nature of climate-driven risks ( [[#McLeod--2019|McLeod et al., 2019]] ; [[#National%20Academies%20of%20Sciences--2019|National Academies of Sciences, 2019]] ; [[#Coleman--2020b|Coleman et al., 2020b]] ). Modelling studies indicate that available practices will not prevent degradation of coral reefs from &gt;1.5°C of global average surface warming (Figure 3.25; [[#National%20Academies%20of%20Sciences%20Engineering%20and%20Medicine--2019|National Academies of Sciences Engineering and Medicine, 2019]] ; [[#Condie--2021|Condie et al., 2021]] ; [[#Hafezi--2021|Hafezi et al., 2021]] ). Proposed interventions include assisted migration ( [[#Boström-Einarsson--2020|Boström-Einarsson et al., 2020]] ; [[#Fredriksen--2020|Fredriksen et al., 2020]] ; [[#Morris--2020c|Morris et al., 2020c]] ), assisted evolution ( [[#Bay--2019|Bay et al., 2019]] ; [[#National%20Academies%20of%20Sciences--2019|National Academies of Sciences, 2019]] ) and other engineering solutions like artificial shading and enhanced upwelling ( [[#Condie--2021|Condie et al., 2021]] ; [[#Kleypas--2021|Kleypas et al., 2021]] ).

<div id="_idContainer117" class="Figure"></div>

[[File:d481dbbb29b57218790cb7abc53fb919 IPCC_AR6_WGII_Figure_3_025.png]]

'''Figure 3.25 |''' '''Implemented and potential future adaptations in ocean and coastal ecosystems.'''

'''(a)''' Global implementation since 1970 of (top) cumulative habitat-restoration projects ( [[#Duarte--2020|Duarte et al., 2020]] ), (middle) cumulative area-based conservation protected area (MPA total) ( [[#Boonzaier--2016|Boonzaier and Pauly, 2016]] ), no-take areas (UN Environment World Conservation Monitoring Centre et al., 2018; [[#UNEP-WCMC--2019|UNEP-WCMC, 2019]] ) and (bottom) percentage of total fish stocks rebuilt ( [[#Kleisner--2013|Kleisner et al., 2013]] ).

'''(b)''' Adaptation pathways for coral reefs to maintain healthy cover (line weight: solid lines, ''likely'' effectiveness; dashed lines, ''more likely'' ''than not'' to ''likely ;'' dotted lines = ''unlikely to more likely than not'' ), with confidence noted for each intervention ( [[#3.4.2.1|Section 3.4.2.1]] , 3.6.3.2; [[#Anthony--2019|Anthony et al., 2019]] ; [[#National%20Academies%20of%20Sciences--2019|National Academies of Sciences, 2019]] )

'''(c)''' As in (b), but for mangrove ecosystems. (Underlying data are available in Tables SM3.4–3.6.)

Transplanting heat-tolerant coral colonies can increase reef resistance to bleaching ( [[#Morikawa--2019|Morikawa and Palumbi, 2019]] ; [[#Howells--2021|Howells et al., 2021]] ) but potentially lower species diversity and alter ecosystem function ( [[#3.4.2.1|Section 3.4.2.1]] ). Genetic manipulation or assisted evolution that propagates genes from heat-tolerant populations could enhance restoration of corals ( [[#Anthony--2017|Anthony et al., 2017]] ; [[#Epstein--2019|Epstein et al., 2019]] ) and kelp ( ''medium agreement, limited evidence'' ) ( [[#Coleman--2019|Coleman and Goold, 2019]] ; [[#Coleman--2020b|Coleman et al., 2020b]] ; [[#Fredriksen--2020|Fredriksen et al., 2020]] ; [[#Wade--2020|Wade et al., 2020]] ). Managed breeding of corals has also had limited success in the laboratory and at small local scales ( [[#National%20Academies%20of%20Sciences--2019|National Academies of Sciences, 2019]] ). There is also ''limited evidence'' that physiological interventions, such as algal-symbiont or microbiome manipulation, could increase coral thermal tolerance in the field ( [[#National%20Academies%20of%20Sciences--2019|National Academies of Sciences, 2019]] ). Employing the natural adaptive capacity of species or individuals in active restoration for corals and kelps with current technology involves fewer risks than assisted evolution or long-distance relocation ( ''high confidence'' ) ( [[#Filbee-Dexter--2019|Filbee-Dexter and Smajdor, 2019]] ; [[#National%20Academies%20of%20Sciences--2019|National Academies of Sciences, 2019]] ). More ambitious engineered interventions like reef shading remain theoretical and not scalable to the reef level ( [[#Condie--2021|Condie et al., 2021]] ). Debate continues on how to apply planned adaptation in cost-effective ways that will accomplish the intended goals ( [[#National%20Academies%20of%20Sciences--2019|National Academies of Sciences, 2019]] ; [[#Duarte--2020|Duarte et al., 2020]] ; [[#Kleypas--2021|Kleypas et al., 2021]] ).

Models show that a combination of available management approaches (restoration, reducing non-climate drivers) and speculative interventions (e.g., enhanced corals, reef shading) can contribute to sustaining some coral reefs beyond 1.5°C of global warming with declining effectiveness beyond 2°C of global warming ( ''medium confidence'' ) (Figure 3.25; WGII Chapter 17). These proposed interventions are also currently theoretical and impractical over large scales; for example, engineered solutions like reef shading are untested and not scalable at the reef level ( [[#Condie--2021|Condie et al., 2021]] ). Existing projects suggest that restoration and ecological interventions to habitat-forming ecosystems have the additional benefits of raising local awareness, promoting tourism, and creating jobs and economic benefits ( [[#Fadli--2012|Fadli et al., 2012]] ; [[#Boström-Einarsson--2020|Boström-Einarsson et al., 2020]] ; [[#Hafezi--2021|Hafezi et al., 2021]] ), provided communities are involved in planning, operation and monitoring ( [[#Boström-Einarsson--2020|Boström-Einarsson et al., 2020]] ).

<div id="3.6.3.3" class="h3-container"></div>

<span id="enablers-barriers-and-limitations-of-adaptation-and-mitigation"></span>
==== 3.6.3.3 Enablers, Barriers and Limitations of Adaptation and Mitigation ====

<div id="h3-40-siblings" class="h3-siblings"></div>

Not only is mitigation necessary to support ocean and coastal adaptation ( [[#Pörtner--2014|Pörtner et al., 2014]] ; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ), but the global emission pathways also impose limits to ocean and coastal adaptation, with lower warming levels enabling greater effectiveness of adaptations ( ''high confidence'' ) (Figure 3.25). [[IPCC:Wg2:Chapter:Chapter-17|Chapter 17]] broadly assesses the limits to adaptation, while this section focuses on barriers and limits to adaptation imposed by cultural ( [[#3.6.3.3.1|Section 3.6.3.3.1]] ), economic ( [[#3.6.3.3.2|Section 3.6.3.3.2]] ) and governance ( [[#3.6.3.3.3|Section 3.6.3.3.3]] ) dimensions ( [[#Hinkel--2018|Hinkel et al., 2018]] ). Globally, these factors more strongly influence ocean development than does local natural resource availability ( [[#Cisneros-Montemayor--2021|Cisneros-Montemayor et al., 2021]] ), and are key to avoiding maladaptation. This section also assesses enablers and limits to mitigation ( [[#3.6.3.3.4|Section 3.6.3.3.4]] ).

<div id="3.6.3.3.1" class="h4-container"></div>

<span id="sociocultural-dimensions-culture-ethics-identity-behaviour"></span>
===== 3.6.3.3.1 Sociocultural dimensions (culture, ethics, identity, behaviour) =====

<div id="h4-25-siblings" class="h4-siblings"></div>

Every coastal community values marine ecosystems for more than the material and intangible resources they deliver, or the physical protection they offer ( [[#Díaz--2018|Díaz et al., 2018]] ). Cultural services that provide identity, spiritual and cultural continuity, religious meaning or options for the future (e.g., genetic or mineral resources) ( [[#Bindoff--2019a|Bindoff et al., 2019a]] ) are not substitutable. Furthermore, interactions between climate impacts and existing inequalities can threaten the human rights of already-marginalised peoples by disrupting livelihoods and food security, which further erodes people’s social, economic and cultural rights ( [[#Finkbeiner--2018|Finkbeiner et al., 2018]] ). For instance, European colonisation and ongoing development blocked the Cucapá Indigenous People’s access and rights to resources in the Colorado River Delta, USA, over the 20th century. Recent reallocation of water rights and fishing access is allowing the Cucapá people to reconstruct their cultural identity ( [[#Sangha--2019|Sangha et al., 2019]] ), but future climate-change impacts could reverse the community’s recovery of their cultural heritage. Adaptations that consider local needs may help sustain cultural services ( [[#Ortíz%20Liñán--2021|Ortíz Liñán and Vázquez Solís, 2021]] ).

Interactions with oceans are fundamental to the identities of many coastal Indigenous Peoples ( [[#Norman--2017|Norman, 2017]] ), and this influences Indigenous responses to climate hazards and adaptation. Around 30 million Indigenous Peoples live along coasts ( [[#Cisneros-Montemayor--2016|Cisneros-Montemayor et al., 2016]] ). Seafood consumption among Indigenous Peoples is much higher than for non-Indigenous populations, and marine species support many cultural, medicinal and traditional activities contributing to public health ( [[#3.5.3|Section 3.5.3.1]] ; [[#Kenny--2018|Kenny et al., 2018]] ). Perpetuation of Indigenous cultures depends on protecting marine ecosystems and on adapting to changes in self-led ways ( [[#3.5.6|Section 3.5.6]] ; [[#Sangha--2019|Sangha et al., 2019]] ) that promote self-determination ( [[#von%20der%20Porten--2019|von der Porten et al., 2019]] ). Indigenous resurgence, or reinvigorating Indigenous ways of life and traditional management, can include marine resource protection and ocean-sector development founded on culturally appropriate strategies and partnerships that are consistent with traditional norms and beneficial to local communities ( [[#von%20der%20Porten--2019|von der Porten et al., 2019]] ). Successful adaptation would simultaneously improve ecosystem health and address current and historical inequities ( [[#Bennett--2018|Bennett, 2018]] ). Examples include practicing traditional resource management, protecting traditional territories, engaging with monitoring, collaborations with non-Indigenous partners and reinvesting benefits into capacity-building within communities ( [[#von%20der%20Porten--2019|von der Porten et al., 2019]] ; [[#Equator%20Initiative--2020|Equator Initiative, 2020]] ). The legitimacy of different adaptation strategies depends on local and Indigenous Peoples’ acceptance, which is based on cultural values ( [[#Adger--2017|Adger et al., 2017]] ); financial gain cannot compensate for loss of IK or LK ( [[#Wilson--2020b|Wilson et al., 2020b]] ). Palau’s recent goal of shifting seafood consumption away from reef fishes (Remengesau Jr., 2019) as well as limiting and closely monitoring the expansion of ecotourism was prompted by the cultural importance of protecting these reefs and associated traditional fisheries for local consumption, a recognition of the importance of tourism and the hazard of climate change ( [[#Wabnitz--2018a|Wabnitz et al., 2018a]] ).

Adaptations implemented at the local level that consider IKLK systems are beneficial ( ''high confidence'' ) ( [[#Nalau--2018|Nalau et al., 2018]] ; [[#Sultana--2019|Sultana et al., 2019]] ). Studies in SIDS and the Arctic have shown how IKLK facilitate the success of EbA ( [[#Nalau--2018|Nalau et al., 2018]] ; [[#Peñaherrera-Palma--2018|Peñaherrera-Palma et al., 2018]] ; [[#Raymond-Yakoubian--2018|Raymond-Yakoubian and Daniel, 2018]] ), reinforce and improve institutional approaches and enhance the provision of ecosystem services ( [[#Ross--2019|Ross et al., 2019]] ; [[#Terra%20Stori--2019|Terra Stori et al., 2019]] ). Perspectives on adaptation also vary among groups of age, race, (dis)ability, class, caste and gender ( [[#Wilson--2020b|Wilson et al., 2020b]] ), so engaging different groups results in more robust and equitable adaptation to climate change (Cross-Chapter Box GENDER in Chapter 18; [[#McLeod--2018|McLeod et al., 2018]] ). Some coastal communities have developed substantial social capital and dense local networks based on trust and reciprocity ( [[#Petzold--2015|Petzold and Ratter, 2015]] ), with individual and community flexibility to learn, adapt and organise themselves to help local adaptation governance ( [[#Silva--2020|Silva et al., 2020]] ). Recent evidence suggests that policies supporting local institutions can improve adaptation outcomes ( ''medium confidence'' ) ( [[#Berman--2020|Berman et al., 2020]] ). Coastal communities can be engaged using novel approaches to co-generate adaptation solutions ( [[#van%20der%20Voorn--2017|van der Voorn et al., 2017]] ; [[#Flood--2018|Flood et al., 2018]] ) that benefit education ( [[#Koenigstein--2020|Koenigstein et al., 2020]] ) and engagement in adaptation processes ( [[#Rumore--2016|Rumore et al., 2016]] ). Successful adaptation implementation in line with climate resilient development pathways (WGII Chapter 18) depends on bottom-up, participatory and inclusive processes ( [[#3.6.1|Section 3.6.1.2.1]] ) that engage diverse stakeholders ( [[#Basel--2020|Basel et al., 2020]] ; [[#McNamara--2020|McNamara et al., 2020]] ; [[#Ogier--2020|Ogier et al., 2020]] ; [[#Williams--2020|Williams et al., 2020]] ) and protect Indigenous customary rights ( [[#Farbotko--2019|Farbotko and McMichael, 2019]] ; [[#Ford--2020|Ford et al., 2020]] ), empower women and give rights to climate refugees ( [[#McLeod--2018|McLeod et al., 2018]] ).

<div id="3.6.3.3.2" class="h4-container"></div>

<span id="economic-dimensions-planning-finance-costs"></span>
===== 3.6.3.3.2 Economic dimensions (planning, finance, costs) =====

<div id="h4-26-siblings" class="h4-siblings"></div>

Finance is a key barrier globally for ocean health, governance and adaptation to climate change ( ''high agreement'' ) (Annex II: Glossary; Cross-Chapter Box FINANCE in Chapter 17; [[#Hinkel--2018|Hinkel et al., 2018]] ; [[#Miller--2018|Miller et al., 2018]] ; [[#Wabnitz--2019|Wabnitz and Blasiak, 2019]] ; [[#Woodruff--2020|Woodruff et al., 2020]] ; [[#Sumaila--2021|Sumaila et al., 2021]] ). Global adaptation finance was estimated to total 30 billion USD yr –1 in 2017–2018, or 5% of all climate finance ( [[#CPI--2019|CPI, 2019]] ), with no tracking specifically for coastal or marine adaptation in low- to middle-income countries. Marine-focused adaptation finance is difficult to trace and label due to the cross-sectoral nature of many projects ( [[#Blasiak--2018|Blasiak and Wabnitz, 2018]] ) and the lack of clear definitions about what qualifies as adaptation or as new and additional finance ( [[#Donner--2016|Donner et al., 2016]] ; [[#Weikmans--2019|Weikmans and Roberts, 2019]] ). Finance for marine conservation from Overseas Development Assistance doubled between 2003 and 2016, reaching 634 million USD in 2016, similar to the level provided by philanthropic foundations ( [[#Berger--2019|Berger et al., 2019]] ). Yet coastal adaptation to SLR alone is projected to cost hundreds of billions of USD yr –1 , depending on the model and emission scenario (e.g., [[#Wong--2014|Wong et al., 2014]] ; [[#Nicholls--2019|Nicholls et al., 2019]] ). Economic and financing barriers to marine adaptation are often higher in low- to middle-income countries, where resources influence governance and constrain options for implementation and maintenance ( ''high confidence'' ) ( [[#Hinkel--2018|Hinkel et al., 2018]] ; [[#Klöck--2019|Klöck and Nunn, 2019]] ; [[#Tompkins--2020|Tompkins et al., 2020]] ), and impacts on their coastal and marine ecosystems could total several percentage points of their gross domestic product ( [[#Wong--2014|Wong et al., 2014]] ). Current financial flows are insufficient to meet the costs of coastal and marine impacts of climate change ( ''very high confidence'' ) and ocean-focused finance is unevenly distributed, with higher flows within, and to, developed countries ( ''very high confidence'' ).

Development assistance can help resolve resource constraints, but additional governance and coordination challenges can arise from short-term, project-based funding, shifting the priorities of donor institutions and the pressures placed on human resources in the receiving nation ( [[#Parsons--2019|Parsons and Nalau, 2019]] ; [[#Nunn--2020|Nunn et al., 2020]] ). Innovative policy instruments, such as concessional loans, tax-policy reforms, climate bonds and public-debt forgiveness, can supplement traditional financial instruments ( [[#Bisaro--2018|Bisaro and Hinkel, 2018]] ; [[#McGowan--2020|McGowan et al., 2020]] ). Mechanisms for solving the persistent problem of securing upfront investments for coastal protection and other adaptation measures ( [[#Bisaro--2018|Bisaro and Hinkel, 2018]] ; [[#Moser--2019|Moser et al., 2019]] ; [[#Kok--2021|Kok et al., 2021]] ) include integrating adaptation investments into insurance schemes ( [[#Reguero--2020|Reguero et al., 2020]] ) and using debt financing to bridge the time until benefits are realised ( [[#Ware--2020|Ware and Banhalmi-Zakar, 2020]] ). Insurance mechanisms that link payments to losses from a trigger event (e.g., MHW) can confer resilience to marine-dependent communities ( [[#Sumaila--2021|Sumaila et al., 2021]] ). All innovative financial instruments are most effective when they are inclusive and reach vulnerable groups and marginalised communities ( ''low evidence, high agreement'' ) ( [[#Claudet--2020a|Claudet et al., 2020a]] ; [[#Sumaila--2021|Sumaila et al., 2021]] ).

Countries with large ocean areas within their EEZs have opportunities to develop ‘blue–green economies’ to reduce emissions and finance adaptation pathways ( [[#Chen--2018a|Chen et al., 2018a]] ; [[#Lee--2020|Lee et al., 2020]] ). Shifting from grants to results-based financing can help attract more private capital to ocean adaptation ( [[#Lubchenco--2016|Lubchenco et al., 2016]] ; [[#Claudet--2020a|Claudet et al., 2020a]] ). Public–private partnerships can also increase ocean adaptation finance ( [[#Goldstein--2019|Goldstein et al., 2019]] ; [[#Sumaila--2021|Sumaila et al., 2021]] ). For example, the financial benefits that biodiversity conservation confers to seafood harvest resilience could be used to leverage industry participation in adaptation and conservation finance ( [[#Barbier--2018|Barbier et al., 2018]] ). Connecting restoration of blue carbon ecosystems with offset markets (e.g., [[#Vanderklift--2019|Vanderklift et al., 2019]] ) shows potential, but uncertainties remain about the international emissions trading under the UN Framework Convention on Climate Change and climate impacts on blue carbon ecosystems ( [[#3.6.3.1|Section 3.6.3.1.6]] ; [[#Lovelock--2017a|Lovelock et al., 2017a]] ; [[#Macreadie--2019|Macreadie et al., 2019]] ).

Transparency, coherence between different actors and initiatives, and project monitoring and evaluation enhance success in adapting and achieving SDG14 (Life Below Water) ( [[#Blasiak--2019|Blasiak et al., 2019]] ). Maladaptation (WGII Chapter 16; [[#Magnan--2016|Magnan et al., 2016]] ) is a common risk of current project-based funding due to the pressure to produce concrete results ( ''medium confidence'' ) ( [[#Parsons--2019|Parsons and Nalau, 2019]] ; [[#Nunn--2020|Nunn et al., 2020]] ; [[#Nunn--2021|Nunn et al., 2021]] ). Maladaptation can be avoided through a focus on building adaptive capacity, community-based management, drivers of vulnerability and site-specific measures ( ''low confidence'' ) ( [[#Magnan--2018|Magnan and Duvat, 2018]] ; [[#Piggott-McKellar--2020|Piggott-McKellar et al., 2020]] ; [[#Schipper--2020|Schipper, 2020]] ). More research is needed to identify ways that governance and financing agreements can help overcome financial barriers and sociocultural constraints to avoid maladaptation in coastal ecosystems ( ''high confidence'' ) ( [[#Hinkel--2018|Hinkel et al., 2018]] ; [[#Miller--2018|Miller et al., 2018]] ; [[#Piggott-McKellar--2020|Piggott-McKellar et al., 2020]] ; [[#Schipper--2020|Schipper, 2020]] ).

<div id="3.6.3.3.3" class="h4-container"></div>

<span id="governance-dimension-institutional-settings-decision-making"></span>
===== 3.6.3.3.3 Governance dimension (institutional settings, decision making) =====

<div id="h4-27-siblings" class="h4-siblings"></div>

Ocean governance has become increasingly complex as new initiatives, new international agreements, institutions and scientific evidence arise at global, national and subnational scales ( ''high agreement'' ) ( [[#Bindoff--2019a|Bindoff et al., 2019a]] ; [[#Scobie--2019b|Scobie, 2019b]] ), limiting the present effectiveness of adaptation ( [[#IPCC--2019c|IPCC, 2019c]] ). Marine climate governance is within the normatively contested marine governance space ( [[#Frazão%20Santos--2020|Frazão Santos et al., 2020]] ), which is influenced by geopolitics ( [[#Gray--2020|Gray et al., 2020]] ) and profit maximisation ( [[#Flannery--2016|Flannery et al., 2016]] ; [[#Haas--2021|Haas et al., 2021]] ) in ways that can entrench exclusionary processes in decision making, science management and funding ( [[#Levin--2018|Levin et al., 2018]] ). This limits just and inclusive ocean governance ( [[#Bennett--2018|Bennett, 2018]] ), perpetuates historical and cultural extractive practices and climate inaction, and leaves little space for Indigenous-led adaptation frameworks and approaches ( [[#Nursey-Bray--2019|Nursey-Bray et al., 2019]] ). At the national level, ocean governance for climate-change adaptation is often transversal, requiring consideration of biophysical and environmental conditions ( [[#Furlan--2020|Furlan et al., 2020]] ) while fitting into existing economic ( [[#Kim--2020|Kim, 2020]] ) and political processes. Adaptation governance that couples existing top-down structures with decentralised and participatory approaches generates shared goals and unlocks required resources and monitoring ( [[#Gupta--2016|Gupta et al., 2016]] ; [[#Haas--2021|Haas et al., 2021]] ).

Communities and governments at all levels increasingly use decision-making frameworks (e.g., structured decision making) or decision-analysis tools to evaluate trade-offs between different responses, rather than applying generic best practices to different physical, technical or cultural contexts ( ''high confidence'' ) ( [[#Watkiss--2015|Watkiss et al., 2015]] ; [[#Haasnoot--2019|Haasnoot et al., 2019]] ; [[#Palutikof--2019|Palutikof et al., 2019]] ). Increased effort has also been devoted to developing climate services (actionable information and data products) that bridge the gap between climate prediction and decision making ( [[#Hewitt--2020|Hewitt et al., 2020]] ). Climate services have the potential to inform decision making related to disaster-risk reduction, adaptation responses, marine environmental management (e.g., fisheries management and MPA management) and ocean-based climate mitigation (e.g., renewable-energy installations) ( [[#Le%20Cozannet--2017|Le Cozannet et al., 2017]] ; [[#Gattuso--2019|Gattuso et al., 2019]] ; [[#Gattuso--2021|Gattuso et al., 2021]] ). Although improving observational and modelling capacity is important to developing ocean-focused services, particularly in high-risk regions like SIDS where regional climate projections are scarce (WGI AR6 Chapter 9; [[#Morim--2019|Morim et al., 2019]] ; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ), data are not the only limiting factor in decision making ( [[#Weichselgartner--2019|Weichselgartner and Arheimer, 2019]] ). Focusing on user engagement, relationship building and the decision-making context ensures that climate services are useful to, and used by, different stakeholders ( ''high confidence'' ) ( [[#Soares--2018|Soares et al., 2018]] ; [[#Mackenzie--2019|Mackenzie et al., 2019]] ; [[#Weichselgartner--2019|Weichselgartner and Arheimer, 2019]] ; [[#Findlater--2021|Findlater et al., 2021]] ; [[#West--2021|West et al., 2021]] ).

<div id="3.6.3.3.4" class="h4-container"></div>

<span id="mitigation"></span>
===== 3.6.3.3.4 Mitigation =====

<div id="h4-28-siblings" class="h4-siblings"></div>

Ocean and coastal NbS can contribute to global mitigation efforts, especially with ocean renewable energy and restoration and preservation of carbon ecosystems (see Box 3.4; [[#3.6.2.3|Section 3.6.2.3]] ). Technological, economic and financing barriers presently hamper development of renewable ocean energy (AR6 WGIII Chapter 6). Such development could help small nations reliant on imported fuel meet their climate-mitigation goals and decrease risk from global fuel-supply dynamics ( [[#Millar--2017|Millar et al., 2017]] ; [[#Chen--2018a|Chen et al., 2018a]] ), but progress is limited by lack of investment ( [[#Millar--2017|Millar et al., 2017]] ; [[#Lee--2020|Lee et al., 2020]] ) or equipment ( [[#Aderinto--2018|Aderinto and Li, 2018]] ; [[#Rusu--2018|Rusu and Onea, 2018]] ). Wave-energy installations, possibly co-located with wind turbines ( [[#Perez-Collazo--2018|Perez-Collazo et al., 2018]] ), are promising for both low- to middle-income nations and areas with significant island or remote coastal geographies ( [[#Lavidas--2016|Lavidas and Venugopal, 2016]] ; [[#Bergillos--2018|Bergillos et al., 2018]] ; [[#Jakimavičius--2018|Jakimavičius et al., 2018]] ; [[#Kompor--2018|Kompor et al., 2018]] ; [[#Penalba--2018|Penalba et al., 2018]] ; [[#Saprykina--2018|Saprykina and Kuznetsov, 2018]] ; [[#Lavidas--2019|Lavidas, 2019]] ). Wave-energy capture may also diminish storm-induced coastal erosion ( [[#Abanades--2018|Abanades et al., 2018]] ; [[#Bergillos--2018|Bergillos et al., 2018]] ). Tidal energy is a relatively new technology ( [[#Haslett--2018|Haslett et al., 2018]] ; [[#Liu--2018|Liu et al., 2018]] ; [[#Neill--2018|Neill et al., 2018]] ) with limiting siting requirements ( [[#Mofor--2013|Mofor et al., 2013]] ). Ocean renewable-energy expansion faces other technological obstacles including lack of implementable or scalable energy-capture devices, access to offshore sites, competing coastal uses, potential environmental impacts and lack of power-grid infrastructure at the coast ( [[#Aderinto--2018|Aderinto and Li, 2018]] ; [[#Neill--2018|Neill et al., 2018]] ).

<div id="cross-chapter-box-slr" class="h2-container box-container"></div>

'''Cross-Chapter Box SLR | Sea Level Rise'''
<div id="h2-33-siblings" class="h2-siblings"></div>

Authors: Gonéri Le Cozannet (France, Chapter 13, CCP4), Judy Lawrence (New Zealand, Chapter 11), David S. Schoeman (Australia, Chapter 3), Ibidun Adelekan (Nigeria, Chapter 9), Sarah R. Cooley (USA, Chapter 3), Bruce Glavovic (New Zealand/South Africa, Chapter 18, CCP2), Marjolijn Haasnoot (The Netherlands, Chapter 13, CCP2), Rebecca Harris (Australia, Chapter 2), Wolfgang Kiessling (Germany, Chapter 3), Robert E. Kopp (USA, WGI), Aditi Mukherji (Nepal, Chapter 4), Patrick Nunn (Australia, Chapter 15), Dieter Piepenburg (Germany, Chapter 13), Daniela Schmidt (UK/Germany, Chapter 13), Craig T. Simmons (Australia), Chandni Singh (India, Chapter 10, CCP2), Aimée Slangen (The Netherlands, WGI), Seree Supratid (Thailand, Chapter 4).

Sea level rise is already impacting ecosystems, human livelihoods, infrastructure, food security and climate mitigation at the coast and beyond. Ultimately, it threatens the existence of cities and settlements in low-lying areas, and some island nations and their cultural heritage (Chapters 9–15; Cross-Chapter Papers 2, 4; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ). The challenge can be addressed by mitigation of climate change and coastal adaptation.

'''Current impacts of sea level rise'''
The rate of global mean SLR was 1.35 mm yr –1 (0.78–1.92 mm yr –1 , ''very likely'' range) during 1901–1990, faster than during any century in at least 3000 years ( ''high confidence'' ) (WGI AR6 Chapter 9; [[#Stanley--1994|Stanley and Warne, 1994]] ; [[#Woodroffe--2016|Woodroffe et al., 2016]] ; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ). Global mean SLR has accelerated to 3.25 mm yr –1 (2.88–3.61 mm yr –1 , ''very likely'' range) during 1993–2018 ( ''high confidence'' ). Extreme sea levels have increased consistently across most regions (WGI AR6 Chapter 9; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ). The largest observed changes in coastal ecosystems are being caused by the concurrence of human activities, waves, current-induced sediment transport and extreme storm events ( ''medium confidence'' ) (Chapters 3, 15, 16; [[#Takayabu--2015|Takayabu et al., 2015]] ; [[#Mentaschi--2018|Mentaschi et al., 2018]] ; [[#Duvat--2019|Duvat, 2019]] ; [[#Murray--2019|Murray et al., 2019]] ; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ). Early impacts of accelerating SLR detected at sheltered or subsiding coasts include chronic flooding at high tides, wetland salinisation and ecosystem transitions, increased erosion and coastal flood damage (Chapters 3, 11, 13–16; WGI AR6 Chapter 9; [[#Sweet--2014|Sweet and Park, 2014]] ; [[#Moftakhari--2015|Moftakhari et al., 2015]] ; [[#Nunn--2017|Nunn et al., 2017]] ; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ; [[#Sharples--2020|Sharples et al., 2020]] ; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ; [[#Strauss--2021|Strauss et al., 2021]] ). The exposure of many coastal populations and ecosystems to SLR is high: economic development is disproportionately concentrated in and around coastal cities and settlements ( ''virtually certain'' ) (Chapters 3, 9–15; Cross-Chapter Papers 2, 4).

'''Projected risks to coastal communities, infrastructure and ecosystems'''
Risks from SLR are ''very likely'' to increase by one order of magnitude well before 2100 without adaptation and mitigation action as agreed by parties to the Paris Agreement ( ''very high confidence'' ). Global mean SLR is ''likely'' to continue accelerating under SSP1-2.6 and more strongly forced scenarios (Figure BoxSLR1; WGI AR6 Chapter 9; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ), increasing the risk of chronic coastal flooding at high tide, serious flooding during extreme events such as swells, storms and hurricanes, and erosion, and coastal ecosystem losses across many low-lying and erodible coasts ( ''very high confidence'' ) (Chapters 3, 9–15; Cross-Chapter Paper 2; [[#Hinkel--2014|Hinkel et al., 2014]] ; [[#McLachlan--2018|McLachlan and Defeo, 2018]] ; [[#Kulp--2019|Kulp and Strauss, 2019]] ; [[#Vousdoukas--2020b|Vousdoukas et al., 2020b]] ). The compounding of rainfall, river flooding, rising water tables, coastal surges and waves are projected to exacerbate SLR impacts on low-lying areas and rivers further inland (Chapters 4, 11–15; [[#Bevacqua--2020|Bevacqua et al., 2020]] ).

There is ''high confidence'' that coastal risks will increase by at least one order of magnitude over the 21st century due to committed SLR ( [[#Hinkel--2013|Hinkel et al., 2013]] ; [[#Hinkel--2014|Hinkel et al., 2014]] ; [[#IPCC--2019b|IPCC, 2019b]] ). Exposure of population and economic assets to coastal hazards is projected to increase over the next decades, particularly in coastal regions with fast-growing populations in Africa, Southeast Asia and Small Islands ( ''medium evidence'' ) (Chapters 9–15; Cross-Chapter Papers 2, 4; [[#Neumann--2015|Neumann et al., 2015]] ; [[#Jones--2016|Jones and O’Neill, 2016]] ; [[#Merkens--2016|Merkens et al., 2016]] ; [[#Merkens--2018|Merkens et al., 2018]] ; [[#Rasmussen--2020|Rasmussen et al., 2020]] ). For RCP8.5, 2.5–9% of the global population and 12–20% of the global gross domestic product is projected to be exposed to coastal flooding by 2100 ( [[#Kulp--2019|Kulp and Strauss, 2019]] ; [[#Kirezci--2020|Kirezci et al., 2020]] ; [[#Rohmer--2021|Rohmer et al., 2021]] ). Above 3°C global warming levels (GWL) and with low adaptation, SLR may cause disruptions to ports and coastal infrastructure ( [[#Camus--2019|Camus et al., 2019]] ; [[#Christodoulou--2019|Christodoulou et al., 2019]] ; [[#Verschuur--2020|Verschuur et al., 2020]] ; [[#Yesudian--2021|Yesudian and Dawson, 2021]] ), which in turn may cascade and amplify across sectors and regions, generating impacts to financial systems (Chapters 11, 13; [[#Mandel--2021|Mandel et al., 2021]] ). Depending on the hydrogeological context, SLR causes salinisation of groundwater, estuaries, wetlands and soils, adding constraints to water management and livelihoods in agriculture sectors, for example, in deltas (Chapters 9, 15; Cross-Chapter Paper 4; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ; [[#Nicholls--2020|Nicholls et al., 2020]] ).

Coastal ecosystems can migrate landward or grow vertically in response to SLR, but their resilience and capacity to keep up with SLR will be compromised by ocean warming and other drivers, depending on regions and species, for example, above 1.5°C for coral reefs ( ''high confidence'' ) (Chapters 3, 16; [[#IPCC--2018|IPCC, 2018]] ; [[#Melbourne--2018|Melbourne et al., 2018]] ; [[#Perry--2018|Perry et al., 2018]] ; [[#IPCC--2019b|IPCC, 2019b]] ; [[#Cornwall--2021|Cornwall et al., 2021]] ). Sediments and space for landward retreat are crucial for mangroves, salt marshes and beach ecosystems ( ''high confidence'' ) (Chapter 3; [[#Peteet--2018|Peteet et al., 2018]] ; [[#Schuerch--2018|Schuerch et al., 2018]] ; [[#FitzGerald--2019|FitzGerald and Hughes, 2019]] ; [[#Friess--2019|Friess et al., 2019]] ; [[#Leo--2019|Leo et al., 2019]] ; [[#Schuerch--2019|Schuerch et al., 2019]] ). Loss of habitat is accompanied by loss of associated ecosystem services, including wave-energy attenuation, habitat provision for biodiversity, food production and carbon storage (Chapter 3; Cross-Chapter Box NATURAL in Chapter 2).

Under a high-emissions, low-likelihood/high-impact scenario, where ''low confidence'' ice-sheet mass loss occurs, global mean SLR could exceed the ''likely'' range by more than one additional metre in 2100 (Figure BoxSLR1b; Cross-Chapter Box DEEP in Chapter 17; WGI AR6 Technical Summary and Chapter 9; [[#Arias--2021|Arias et al., 2021]] ; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ). This is a reason for concern given that rapid SLR after the last glacial–interglacial transition caused a drowning of coral reefs ( ''high confidence'' ) ( [[#Camoin--2015|Camoin and Webster, 2015]] ; [[#Sanborn--2017|Sanborn et al., 2017]] ; [[#Webster--2018|Webster et al., 2018]] ), extensive loss of coastal land and islands, habitats and associated biodiversity ( ''high confidence'' ) (AR6 WGI Chapter 9; [[#Fruergaard--2015|Fruergaard et al., 2015]] ; [[#Fernández-Palacios--2016|Fernández-Palacios et al., 2016]] ; [[#Hamilton--2019|Hamilton et al., 2019]] ; [[#Helfensdorfer--2019|Helfensdorfer et al., 2019]] ; [[#Kane--2020|Kane and Fletcher, 2020]] ; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ), and triggered Neolithic migrations in Europe and Australia ( ''medium confidence'' ) (Cross-Chapter Box PALEO in Chapter 1; [[#Turney--2007|Turney and Brown, 2007]] ; [[#Brisset--2018|Brisset et al., 2018]] ; [[#Williams--2018|Williams et al., 2018]] ).

<div id="_idContainer108" class="Box_Header-continued"></div>

Cross-Chapter Box SLR

At centennial time scales, projected SLR represents an existential threat for island nations, low-lying coastal zones and the communities, infrastructure, and cultural heritage therein (Chapters 9–15; Cross-Chapter Paper 4). Even if climate warming is stabilised at 2°C to 2.5°C GWL, coastlines will continue to reshape over millennia, affecting at least 25 megacities and drowning low-lying areas where 0.6–1.3 billion people lived in 2010 ( ''medium confidence'' ) (WGI AR6 Chapter 9; [[#Marzeion--2014|Marzeion and Levermann, 2014]] ; [[#Clark--2016|Clark et al., 2016]] ; [[#Kulp--2019|Kulp and Strauss, 2019]] ; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ; [[#Strauss--2021|Strauss et al., 2021]] ).

'''Solutions, opportunities and limits to adaptation'''
The ability to adapt to current coastal impacts, to cope with future coastal risks and to prevent further acceleration of SLR beyond 2050 depends on immediate mitigation and adaptation actions ( ''very high confidence'' ). The most urgent adaptation challenge is chronic flooding at high tide (Chapters 10, 11, 13–15). Reducing the acceleration of SLR beyond 2050 will only be achieved with fast and profound mitigation of climate change ( [[#Nicholls--2018|Nicholls et al., 2018]] ; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ). Until 2050, adaptation planning and implementation needs are projected to increase significantly in most inhabited coastal regions (see Figure BoxSLR1; WGI AR6 Chapter 9; [[#IPCC--2019b|IPCC, 2019b]] ; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ). For SSP1-2.6 and more strongly forced scenarios, SLR rates continue to increase (WGI AR6 Chapter 9; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ), and so do the scale and frequency of adaptation interventions needed in coastal zones (Figure BoxSLR1; [[#Haasnoot--2020|Haasnoot et al., 2020]] ).

Risks can be anticipated, planned and decided upon, and adaptation interventions can be implemented over the coming decades considering their often long lead- and lifetimes, irrespective of the large uncertainty about SLR beyond 2050 ( ''high confidence'' ) (Figure BoxSLR1; Cross-Chapter Box DEEP in Chapter 17; Cross-Chapter Paper 2; Chapters 11, 13; [[#Haasnoot--2018|Haasnoot et al., 2018]] ; [[#Stephens--2018|Stephens et al., 2018]] ; [[#Stammer--2019|Stammer et al., 2019]] ). Adaptation capacity and governance to manage risks from projected SLR typically require decades to implement and institutionalise ( ''high confidence'' ) (Chapters 11, 13; [[#Haasnoot--2021|Haasnoot et al., 2021]] ). Without considering both short- and long-term adaptation needs, including beyond 2100, communities are increasingly confronted with a shrinking solution space, and adverse consequences are disproportionately borne by exposed and socially vulnerable people (Chapters 1, 8). Sea level rise is ''likely'' to compound social conflict in some settings ( ''high confidence'' ) ( [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ).

Coastal impacts of SLR can be avoided by preventing new development in exposed coastal locations (Chapters 3, 9–15; Cross-Chapter Paper 2; [[#Doberstein--2019|Doberstein et al., 2019]] ; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ). For existing developments, a range of near-term adaptation options exists, including: (a) engineered, sediment- or ecosystem-based protection; (b) accommodation and land-use planning, to reduce the vulnerability of people and infrastructure; (c) advance through, for example, land reclamation; and (d) retreat through planned relocation or displacements and migrations due to SLR (Chapters 9–15; Cross-Chapter Paper 2; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ). Only avoidance and relocation can remove coastal risks for the coming decades, while other measures only delay impacts for a time, have increasing residual risk or perpetuate risk and create ongoing legacy effects and ''virtually certain'' property and ecosystem losses ( ''high confidence'' ) (Cross-Chapter Paper 2; [[#Siders--2019|Siders et al., 2019]] ). Large-scale relocation has immense cultural, political, social and economic costs, and equity implications, which can be reduced by fast implementation of climate mitigation and adaptation policies (Chapter 8; Cross-Chapter Paper 2; [[#Gibbs--2015|Gibbs, 2015]] ; [[#Haasnoot--2021|Haasnoot et al., 2021]] ). While relocation may currently appear socially unacceptable, economically inefficient or technically infeasible today ( [[#Lincke--2021|Lincke and Hinkel, 2021]] ), it becomes the only feasible option as protection costs become unaffordable and the limits to accommodation become obvious (Chapters 11, 13, 15; [[#Hino--2017|Hino et al., 2017]] ; [[#Siders--2019|Siders et al., 2019]] ; [[#Strauss--2021|Strauss et al., 2021]] ). Effective responses to rising sea level involve locally applicable combinations of decision analysis, land-use planning, public participation and conflict resolution approaches; together these can anticipate change and help to chart adaptation pathways, over time addressing the governance challenges due to rising sea level ( ''high confidence'' ) ( [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ).

Ecosystem-based adaptation can reduce impacts on human settlements and bring substantial co-benefits, such as ecosystem services restoration and carbon storage, but they require space for sediment and ecosystems and have site-specific physical limits, at least above 1.5°C GWL ( ''high confidence'' ) (Cross-Chapter Box NATURAL in Chapter 2; Chapters 3, 9, 11, 15; [[#Herbert--2015|Herbert et al., 2015]] ; [[#Brown--2019|Brown et al., 2019]] ; [[#Van%20Coppenolle--2019|Van Coppenolle and Temmerman, 2019]] ; [[#Watanabe--2019|Watanabe et al., 2019]] ; [[#Neijnens--2021|Neijnens et al., 2021]] ). For example, planting and conserving vegetation helps sediment accumulation by dissipating wave energy and reducing impacts of storms, at least at present-day sea levels ( ''high confidence'' ) ( [[#Temmerman--2013|Temmerman et al., 2013]] ; [[#Narayan--2016|Narayan et al., 2016]] ; [[#Romañach--2018|Romañach et al., 2018]] ; [[#Laengner--2019|Laengner et al., 2019]] ; [[#Leo--2019|Leo et al., 2019]] ). Coastal wetlands and ecosystems can be preserved by landward migration ( [[#Schuerch--2018|Schuerch et al., 2018]] ; [[#Schuerch--2019|Schuerch et al., 2019]] ) or sediment supply ( [[#VanZomeren--2018|VanZomeren et al., 2018]] ), but they can be seriously damaged by coastal defences designed to protect infrastructure (Chapters 3, 13; [[#Cooper--2020b|Cooper et al., 2020b]] ). Sediment nourishment can prevent erosion, but it can also negatively impact beach amenities and ecosystems through ongoing dredging, pumping and deposition of sand and silts ( [[#VanZomeren--2018|VanZomeren et al., 2018]] ; [[#de%20Schipper--2021|de Schipper et al., 2021]] ; [[#Harris--2021|Harris et al., 2021]] ).

[[File:9d7ef33b97d234e8d52d2d6d35c26042 IPCC_AR6_WGII_Figure_3_Cross-Chapter_Box_SLR_1.png]]

'''Figure Cross-Chapter BoxSLR.1 |''' '''The challenge of coastal adaptation in the era of sea level rise (SLR):''' '''(a)''' '''typical time scales for the planning, implementation (grey triangles) and operational lifetime of current coastal risk-management measures (blue bars);''' '''(b)''' '''global sea level projections, which are representative of relative SLR projected for 60–70% of global shorelines, within ±20% errors (WGI AR6 Chapter 9; Fox-Kemper et al.''' ''',''' 2021); '''(c)''' frequency of illustrative adaptation decisions to +0.5 m of SLR under different SSP-RCP scenarios. In response to accelerated SLR, adaptation either occurs earlier and faster, or accounts for higher amounts of SLR (e.g., to +1 m instead of to +0.5 m). Adaptation to +0.5 m from today’s sea levels have a lifetime of 90 years for SSP1-2.6, but lifetime is reduced to 60 years for SSP5-8.5 and 30 years for a high-end scenario involving ''low confidence'' processes. Adaptations to +0.5 m are comparable to, for example, the Thames Barrier in the United Kingdom or the Delta Works in the Netherlands, which primarily had an intended lifetime of 100–200 years. Adaptation measures to +0.2 m may include nourishment or wetland or setback zones.

There is increasing evidence that current governance and institutional arrangements are unable to address the escalating risks in low-lying coastal areas worldwide ( ''high confidence'' ). Barriers to adaptation, such as decision making driven by short-term thinking or vested interests, funding limitations and inadequate financial policies and insurance, can be addressed equitably and sustainably through implementation of suites of adaptation options and pathways (Chapters 11, 13, 17–18; Cross-Chapter Paper 2). Improved coastal adaptation governance can be supported by approaches that consider changing risks over time, such as ‘dynamic adaptation pathways’ planning (Chapters 11, 13, 18; Cross-Chapter Box DEEP in Chapter 17). Integrated coastal zone management and land-use and infrastructure planning are starting to consider SLR by, for example, monitoring early signals ( [[#Haasnoot--2018|Haasnoot et al., 2018]] ; [[#Stephens--2018|Stephens et al., 2018]] ; [[#Kool--2020|Kool et al., 2020]] ), updating sea level projections ( [[#Stephens--2017|Stephens et al., 2017]] ; [[#Hinkel--2019|Hinkel et al., 2019]] ; [[#Kopp--2019|Kopp et al., 2019]] ; [[#Stammer--2019|Stammer et al., 2019]] ), considering uncertainties of sea level projections and coastal impacts (e.g., [[#Stephens--2017|Stephens et al., 2017]] ; [[#Jevrejeva--2019|Jevrejeva et al., 2019]] ; [[#Rohmer--2019|Rohmer et al., 2019]] ), as well as engaging with communities, practitioners and scientists, recognising the values of current and future generations (e.g., [[#Nicholls--2014|Nicholls et al., 2014]] ; [[#Buchanan--2016b|Buchanan et al., 2016b]] ). While there is ''high agreement'' that the majority of adaptation needs are not met yet, there is ''robust evidence'' of SLR increasingly being considered in coastal adaptation decision making and being embedded in national and local guidance and regulations ( [[#Nicholls--2014|Nicholls et al., 2014]] ; [[#Le%20Cozannet--2017|Le Cozannet et al., 2017]] ; [[#Lawrence--2018|Lawrence et al., 2018]] ; [[#Kopp--2019|Kopp et al., 2019]] ; [[#McEvoy--2021|McEvoy et al., 2021]] ).

<div id="_idContainer111" class="Box_Header-continued"></div>

Cross-Chapter Box SLR

<div id="FAQ 3.5" class="h2-container"></div>

<span id="faq-3.5-how-can-nature-based-solutions-including-marine-protected-areas-help-us-to-adapt-to-climate-driven-changes-in-the-oceans"></span>
=== FAQ 3.5 | How can nature-based solutions, including marine protected areas, help us to adapt to climate-driven changes in the oceans? ===

<div id="h2-34-siblings" class="h2-siblings"></div>

''Coastal habitats, such as mangroves or vegetated dunes, protect coastal communities from sea level rise and storm surges while supporting fisheries, sequestering carbon and providing other ecosystem services as well. Efforts to restore, conserve and/or recover these natural habitats help people confront the impacts of climate change. These marine nature-based solutions (NbS), such as Marine protected areas (MPAs), habitat restoration and sustainable fisheries, are cost-effective and provide myriad benefits to society.''

In the oceans, NbS comprise attempts to recover, restore or conserve coastal and marine habitats to reduce the impacts of climate change on nature and society. Marine habitats, such as seagrasses and coral reefs, provide services like food and flood regulation in the same way as forests do on land. Coastal habitats, such as mangroves or vegetated dunes, protect coastal communities from sea level rise and storm surges while supporting fisheries as well as recreational and aesthetic services. Seagrasses, coral reefs and kelp forests also provide important benefits that help humans adapt to climate change, including sustainable fishing, recreation and shoreline protection services. By recognising these services and benefits of the ocean, NbS can improve the quality and integrity of the marine ecosystems.

Nature-based solutions offer a wide range of potential benefits, including protecting ecosystem services, supporting biodiversity and mitigating climate change. Coastal and marine examples include MPAs, habitat restoration, habitat development and maintaining sustainable fisheries. While local communities with limited resources might find NbS challenging to implement, they are generally ‘no-regret’ options, which bring societal and ecological benefits regardless of the level of climate change.

Carefully designed and placed MPAs, especially when they exclude fishing, can increase resilience to climate change by removing additional stressors on ecosystems. While MPAs do not prevent extreme events, such as marine heatwaves (FAQ3.2), they can provide marine plants and animals with a better chance to adapt to a changing climate. Current MPAs, however, are often too small, too poorly connected and too static to account for climate-induced shifts in the range of marine species. MPA networks that are large, connected, have adaptable boundaries and are designed following systematic analysis of future climate projections can better support climate resilience.

Habitat restoration and development in coastal systems can support biodiversity, protect communities from flooding and erosion, support the local economy and enhance the livelihoods and well-being of coastal peoples. Restoration of mangroves, salt marshes and seagrass meadows provide effective ways to remove carbon dioxide from the atmosphere and at the same time protect coasts from the impacts of storms and SLR. Active restoration techniques that target heat-resistant individuals or species are increasingly recommended for coral reefs and kelp forests, which are highly vulnerable to marine heatwaves and climate change.

Sustainable fishing is also seen as an NbS because managing marine commercial species within sustainable limits maximises the catch and food production, thus contributing to the UN’s Sustainable Development Goal 2 (Zero Hunger). Currently, the oceans provide 17% of the animal protein eaten by the global population, but the contribution could be larger if fisheries were managed sustainably. Aquaculture, such as oyster farming, can be an efficient and sustainable means of food production and also provide additional benefits like shoreline protection. Through NbS that conserve and restore marine habitats and species, we can sustain marine biodiversity, respond to climate change and provide benefits to society.

[[File:3c662aa1ddeb3cce47d84665d58957a5 IPCC_AR6_WGII_Figure_3_FAQ_3_5.png]]

'''Figure FAQ3.5.1 |''' '''Contributions of nature-based solutions (NbS) in the oceans to the Sustainable Development Goals.''' The icons at the bottom show the Sustainable Development Goals to which NbS in the ocean possibly contribute.

<div id="3.6.4" class="h2-container"></div>

<span id="contribution-to-the-sustainable-development-goals-and-other-relevant-policy-frameworks"></span>
=== 3.6.4 Contribution to the Sustainable Development Goals and Other Relevant Policy Frameworks ===

<div id="h2-23-siblings" class="h2-siblings"></div>

The impacts of climate change on ocean and coastal ecosystems and their services threaten achievement of the UN SDGs by 2030 ( ''high confidence'' ), particularly ocean targets (Table 3.31; [[#Nilsson--2016|Nilsson et al., 2016]] ; [[#Pecl--2017|Pecl et al., 2017]] ; [[#IPCC--2018|IPCC, 2018]] ; [[#Singh--2019a|Singh et al., 2019a]] ; [[#Claudet--2020a|Claudet et al., 2020a]] ). Nevertheless, local to international decision-making bodies have assigned the lowest priority to SDG14, Life Below Water ( [[#Nash--2020|Nash et al., 2020]] ).

<div id="3.6.4.1" class="h3-container"></div>

<span id="climate-mitigation-effects-on-ocean-related-sdgs"></span>
==== 3.6.4.1 Climate Mitigation Effects on Ocean-Related SDGs ====

<div id="h3-41-siblings" class="h3-siblings"></div>

SROCC underscored the need for ambitious mitigation to control climate hazards in the ocean to achieve SDGs ( ''medium evidence, high agreement'' ) ( [[#Bindoff--2019a|Bindoff et al., 2019a]] ; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ). Delays in achieving ocean-dependent SDGs observed in SROCC and SR15 can be addressed with ambitious planned adaptation and mitigation action ( ''high agreement'' ) ( [[#Hoegh-Guldberg--2019b|Hoegh-Guldberg et al., 2019b]] ). Since the ocean can contribute substantially to the attainment of mitigation targets aiming to limit warming to 1.5°C above pre-industrial levels ( [[#Hoegh-Guldberg--2019b|Hoegh-Guldberg et al., 2019b]] ), and to adaptation solutions facilitating attainment of social and economic SDGs, climate policy is treating the ocean less as a victim of climate change and more as a central participant in solving the global climate challenge ( [[#Cooley--2019|Cooley et al., 2019]] ; [[#Hoegh-Guldberg--2019a|Hoegh-Guldberg et al., 2019a]] ; [[#Dundas--2020|Dundas et al., 2020]] ).

Relationships between Climate Action (SDG13) targets and SDG14 targets are mostly synergistic (Figure 3.26; [[#Fuso%20Nerini--2019|Fuso Nerini et al., 2019]] ). Responding to climate-change impacts requires transformative governance ( ''high confidence'' ) (Chapters 1, 18; [[#Collins--2019a|Collins et al., 2019a]] ; Brodie [[#Rudolph--2020|Rudolph et al., 2020]] ; [[#Claudet--2020a|Claudet et al., 2020a]] ), especially for extreme events and higher-impact scenarios (e.g., higher emissions) ( [[#Fedele--2019|Fedele et al., 2019]] ), and for achieving SDGs through one of the global ecosystems transitions (Chapter 18; [[#Sachs--2019|Sachs et al., 2019]] ; Brodie [[#Rudolph--2020|Rudolph et al., 2020]] ). Opportunities to transform ocean governance exist in developing new international and local agreements, regulations and policies that reduce the risks of relocating ocean and coastal activities ( [[#3.6.3.1.1|Section 3.6.3.1.1]] ) or in reinventing established practices ( [[#3.6.3.3.3|Section 3.6.3.3.3]] ). Policy transformations improving ocean sustainability under SDG14 also help address SDG13 (Brodie [[#Rudolph--2020|Rudolph et al., 2020]] ; [[#Dundas--2020|Dundas et al., 2020]] ; [[#Claudet--2021|Claudet, 2021]] ; [[#Sumaila--2021|Sumaila et al., 2021]] ). Emergent situations, such as the COVID-19 pandemic, may provide opportunities to implement transformative ‘green recovery plans’ that support achievement of the SDGs and NDCs (Cross-Chapter Box COVID in Chapter 7).

<div id="_idContainer123" class="Figure"></div>

[[File:e799a5137958685b36b76a4fb2b0f503 IPCC_AR6_WGII_Figure_3_026.png]]

'''Figure 3.26 |''' '''Synergies and trade-offs between SDG13 Climate Action, SDG14 Life Below Water and social, economic and governance SDGs.''' Achieving SDG13 provides positive outcomes and supports the achievement of all SDG14 targets. In turn, meeting SDG14 drives mostly positive interactions with social, economic and governance SDGs. The interaction types, ‘Indivisible’ (inextricably linked to the achievement of another goal), ‘Reinforcing’ (aids the achievement of another goal), ‘Enabling’ (creates conditions that further another goal), ‘Consistent’ (no significant positive or negative interactions) and ‘Constraining’ (limits options on another goal), follow Nilsson et al.’s (2016) scoring system based on the authors’ assessment, and agreement denotes consistency across author ratings. (Full data are available in Table 3.SM.7.)

<div id="3.6.4.2 " class="h3-container"></div>

<span id="contribution-of-ocean-adaptation-to-sdgs"></span>
==== 3.6.4.2 Contribution of Ocean Adaptation to SDGs ====

<div id="h3-42-siblings" class="h3-siblings"></div>

Marine-focused adaptations show promise in helping achieve social SDGs, especially when they are designed to achieve multiple benefits ( ''medium confidence'' ) (Figure 3.26; [[#Ntona--2018|Ntona and Morgera, 2018]] ; [[#Claudet--2020a|Claudet et al., 2020a]] ). Technology- and infrastructure-focused adaptations ( [[#3.6.2.2|Section 3.6.2.2]] ) can help relieve coastal communities from risks associated with poverty (SDG1), hunger (SDG2), health and water sanitation (SDG3 and SDG6), and inequality (SDG10) by supporting aquaculture (Sections 3.5.3, 3.6.3.1), alerting the public about poor water quality (Sections 3.5.5.3, 3.6.3.1) and empowering marginalised groups, such as women and Indigenous Peoples, with decision-relevant information ( ''medium evidence, high agreement'' ) (Sections 3.5.5.3, 3.6.3.1). Effectively implemented and managed marine NbS ( [[#3.6.2.3|Section 3.6.2.3]] ) contribute to attainment of social SDGs by: (a) preserving biodiversity ( [[#Carlton--2018|Carlton and Fowler, 2018]] ; [[#Warner--2018|Warner, 2018]] ; [[#Scheffers--2019|Scheffers and Pecl, 2019]] ), which benefits most ocean and coastal ecosystem services ( [[#3.5.3|Section 3.5.3]] ; Figure 3.22); (b) increasing marine fishery and aquaculture sustainability ( [[#3.6.3|Section 3.6.3]] ); (c) including vulnerable people and communities in management ( [[#3.6.3.2|Section 3.6.3.2.1]] ); (d) lowering risk of flooding from storms and SLR (Cross-Chapter Box SLR in Chapter 3; Sections 3.6.3.1.1); and (e) implementing spatial-management tools that make room for new uses like renewable-energy development ( [[#3.6.3.3.4|Section 3.6.3.3.4]] ). Nature-based solutions can therefore help support achievement of No Poverty (SDG1) ( [[#Ntona--2018|Ntona and Morgera, 2018]] ), Zero Hunger (SDG2), Good Health and Well-Being (SDG3) ( [[#Duarte--2020|Duarte et al., 2020]] ), Affordable and Clean Energy (SDG7) ( [[#Fuso%20Nerini--2019|Fuso Nerini et al., 2019]] ; [[#Levin--2020|Levin et al., 2020]] ) and Reduced Inequality (SDG10). Socio-institutional marine adaptations ( [[#3.6.2.2|Section 3.6.2.2]] ) that support current livelihoods and help develop alternatives can contribute to attainment of social SDGs by enhancing social equity and supporting societal transformation ( ''medium confidence'' ) ( [[#Cisneros-Montemayor--2019|Cisneros-Montemayor et al., 2019]] ; [[#Pelling--2019|Pelling and Garschagen, 2019]] ; [[#Nash--2021|Nash et al., 2021]] ). Even societal changes that are not directly marine related can decrease human vulnerability to ocean and coastal climate risks by improving overall human adaptive capacity ( [[IPCC:Wg2:Chapter:Chapter-1#1.2|Section 1.2]] ).

Marine adaptation also shows promise for helping support achievement of economic SDGs ( ''medium confidence'' ) (Figure 3.26). Marine NbS could help blue-economy frameworks achieve Decent Work and Economic Growth (SDG8) ( [[#Lee--2020|Lee et al., 2020]] ) by sustainably and equitably incorporating ecosystem-based fisheries management, restoration or conservation (Sections 3.6.3.1.2, 3.6.3.2.1, 3.6.3.2.2; [[#Voyer--2018|Voyer et al., 2018]] ; [[#Cisneros-Montemayor--2019|Cisneros-Montemayor et al., 2019]] ; [[#Cohen--2019|Cohen et al., 2019]] ; [[#Okafor-Yarwood--2020|Okafor-Yarwood et al., 2020]] ). Nature-based solutions that involve active restoration or accommodation can contribute to Sustainable Cities and Communities (SDG11) and Infrastructure (SDG9) ( [[#3.6.3.1.1|Section 3.6.3.1.1]] ). Newly developed marine industries and livelihoods associated with NbS might support attainment of Sustainable Communities (SDG11) ( [[#Cisneros-Montemayor--2019|Cisneros-Montemayor et al., 2019]] ). Finance and market mechanisms to support disaster relief or ocean ecosystem services, such as blue carbon or food provisioning, and innovations (SDG9) including new technologies like vessel-monitoring systems ( [[#Kroodsma--2018|Kroodsma et al., 2018]] ), can contribute to Responsible Consumption and Production (SDG12) ( [[#Sumaila--2020|Sumaila and Tai, 2020]] ). Blue-economy growth that includes sustainable shipping, tourism, renewable ocean energy and transboundary fisheries management ( [[#Pinsky--2018|Pinsky et al., 2018]] ) have the potential to contribute to Economic Development (SDG8), affordable and clean energy (SDG7) as well as global mitigation efforts (SDG13) ( [[#Hoegh-Guldberg--2019b|Hoegh-Guldberg et al., 2019b]] ; [[#Duarte--2020|Duarte et al., 2020]] ). Participatory approaches and co-management systems ( [[#3.6.2.1|Section 3.6.2.1]] ) in many maritime sectors can contribute to SDG11 and SDG12 while helping align the blue economy and the SDGs ( ''high agreement'' ) ( [[#Lee--2020|Lee et al., 2020]] ; [[#Okafor-Yarwood--2020|Okafor-Yarwood et al., 2020]] ).

Developing marine adaptation pathways that offer multiple benefits requires transformational adaptation ( ''high confidence'' ) ( [[#Claudet--2020a|Claudet et al., 2020a]] ; [[#Friedman--2020|Friedman et al., 2020]] ; [[#Wilson--2020b|Wilson et al., 2020b]] ; [[#Nash--2021|Nash et al., 2021]] ) that avoids risky and maladaptive actions ( [[#Magnan--2018|Magnan and Duvat, 2018]] ; [[#Ojea--2020|Ojea et al., 2020]] ). Ocean and coastal extreme events and other hazards disproportionately harm the most vulnerable communities in SIDS, tropical and Arctic regions, and Indigenous Peoples (Chapter 8.2.1.2). Presently implemented adaptation activity, at the aggregate level, adversely affects multiple gender targets under SDG5 ( ''high confidence'' ) (Cross-Chapter Box GENDER in Chapter 18). Although women make up over half of the global seafood production workforce (fishing and processing sectors), provide more than half the artisanal landings in the Pacific region ( [[#Harper--2013|Harper et al., 2013]] ), dominate some seafood sectors such as seaweed ( [[#Howard--2019|Howard and Pecl, 2019]] ) and shellfish harvesting ( [[#Turner--2020a|Turner et al., 2020a]] ) and account for 11% of global artisanal fisheries participants ( [[#Harper--2020b|Harper et al., 2020b]] ), they are often not specifically counted in datasets and excluded from decision making and support programmes (Cross-Chapter Box GENDER in Chapter 18; [[#Harper--2020b|Harper et al., 2020b]] ; [[#Michalena--2020|Michalena et al., 2020]] ). Targeted efforts to incorporate knowledge diversity, and include artisanal fishers, women and Indigenous Peoples within international, regional and local policy planning, promote marine adaptation that supports achievement of gender equality (SDG5) and reduces inequalities (SDG10) ( ''limited evidence, high agreement'' ) ( [[#FAO--2015|FAO, 2015]] ). Integrated planning, financing and implementation can help overcome these limitations ( [[#3.6.3.3.2|Section 3.6.3.3.2]] ; Cross-Chapter Box FINANCE in Chapter 17), ensuring that marine adaptations do not compromise overall human equity or specific SDGs ( [[#Österblom--2020|Österblom et al., 2020]] ; [[#Nash--2021|Nash et al., 2021]] ), but are in fact fully synergistic with these goals ( [[#Bennett--2021|Bennett et al., 2021]] ).

<div id="3.6.4.3" class="h3-container"></div>

<span id="relevant-policy-frameworks-for-ocean-adaptation"></span>
==== 3.6.4.3 Relevant Policy Frameworks for Ocean Adaptation ====

<div id="h3-43-siblings" class="h3-siblings"></div>

The intricacy, scope, time scales and uncertainties associated with climate change challenge ocean governance, which already is extremely complex because it encompasses a variety of overlapping spatial scales, concerns and governance structures (see Figure CB3.1 in SROCC Chapter 1; [[#Prakash--2019|Prakash et al., 2019]] ). Assessment of how established global agreements and regional, sectoral or scientific bodies address climate adaptation and resilience, and how current practices can be improved, is found in SM3.5.3.

There is growing momentum to include the ocean in international climate policy ( ''robust evidence'' ), paving the way for a more integrated approach to both mitigation and adaptation. Following adoption of the Paris Agreement in 2015, the UN SDGs (Table 3.31) came into force in 2016, including SDG14 specifically dedicated to Life Below Water (Table 3.31). In 2017, the first UN Ocean Conference was held (United Nations, 2017), the UNFCCC adopted the Ocean Pathway to increase ocean-targeted multilateral climate action ( [[#COP23--2017|COP23, 2017]] ) and the UN Assembly declared 2021–2030 the Decade for Ocean Science for Sustainable Development ( [[#Visbeck--2018|Visbeck, 2018]] ; [[#Lee--2020|Lee et al., 2020]] ). Next, 14 world leaders formed the High-Level Panel for a Sustainable Ocean Economy to produce the New Ocean Action Agenda, founded on 100% sustainable management of national ocean spaces by 2025 ( [[#Ocean%20Panel--2020|Ocean Panel, 2020]] ). All of these initiatives position oceans centrally within the climate-policy and biodiversity-conservation landscapes and seek to develop a coherent effort and common frameworks to achieve marine sustainability ( [[#Visbeck--2018|Visbeck, 2018]] ; [[#Lee--2020|Lee et al., 2020]] ), new economic opportunities ( [[#Konar--2020|Konar and Ding, 2020]] ; [[#Lee--2020|Lee et al., 2020]] ), more equitable outcomes ( [[#Österblom--2020|Österblom et al., 2020]] ) and decisive climate mitigation and adaptation ( [[#Hoegh-Guldberg--2019a|Hoegh-Guldberg et al., 2019a]] ), to achieve truly transformative change ( [[#Claudet--2020a|Claudet et al., 2020a]] ).

'''Table 3.31 |''' Sustainable Development Goals, grouped into broader categories as discussed in this section a

{| class="wikitable"
|-
! Category

! Goal

|-
| Society

| SDG1: No Poverty

SDG2: Zero Hunger

SDG3: Good Health and Well-Being

SDG4: Quality Education

SDG5: Gender Equality

SDG6: Clean Water and Sanitation

SDG7: Affordable and Clean Energy

|-
| Economy

| SDG8: Decent Work and Economic Growth

SDG9: Industry, Innovation and Infrastructure

SDG10: Reduced Inequality

SDG11: Sustainable Cities and Communities

SDG12: Responsible Consumption and Production

|-
| Environment

| SDG13: Climate Action

SDG14: Life Below Water

SDG15: Life on Land

|-
| Governance

| SDG16: Peace and Justice Strong Institutions

SDG17: Partnerships to Achieve the Goals

|}

(a) See http://sdgs.un.org/goals

There is ''high confidence'' in the literature that multilateral environmental agreements need better alignment and integration to support achievement of ambitious international development, climate mitigation and adaptation goals (Swilling et al., 202; [[#Duarte--2020|Duarte et al., 2020]] ; [[#Friedman--2020|Friedman et al., 2020]] ; [[#Conservation%20International%20and%20IUCN--2021|Conservation International and IUCN, 2021]] ; [[#Pörtner--2021b|Pörtner et al., 2021b]] ; [[#Sumaila--2021|Sumaila et al., 2021]] ). The ocean targets of the CBD (e.g., the Post-2020 Global Biodiversity Framework), the SDGs (Agenda 2030) and the Paris Agreement are already inclusive and synergistic ( [[#Duarte--2020|Duarte et al., 2020]] ). However, specific policy instruments and sectors within them could be additionally integrated, especially to address such cross-cutting impacts as ocean acidification and deoxygenation ( [[#Gallo--2017|Gallo et al., 2017]] ; [[#Bindoff--2019a|Bindoff et al., 2019a]] ), increasing plastic pollution ( [[#Ostle--2019|Ostle et al., 2019]] ; [[#Duarte--2020|Duarte et al., 2020]] ), high-seas governance ( [[#Johnson--2019|Johnson et al., 2019]] ; [[#Leary--2019|Leary, 2019]] ) or deep-sea uses ( [[#Wright--2019|Wright et al., 2019]] ; [[#Levin--2020|Levin et al., 2020]] ; [[#Orejas--2020|Orejas et al., 2020]] ). National adaptation plans present opportunities to synergistically build on mitigation to support equitable development ( [[#Morioka--2020|Morioka et al., 2020]] ), economic planning ( [[#Dundas--2020|Dundas et al., 2020]] ; [[#Lee--2020|Lee et al., 2020]] ) and ocean stewardship ( [[#von%20Schuckmann--2020|von Schuckmann et al., 2020]] ). Alignment of multilateral agreements is expected to increase mitigation impact as well as increase adaptation options ( [[#3.6.3|Section 3.6.3]] ; Figure 3.25; [[#Roberts--2020|Roberts et al., 2020]] ). Opportunities to improve multilateral environmental agreements and policies beyond UNFCCC and CBD processes are discussed in SM3.5.3, and an assessment of commercial species-management initiatives and needs is in Chapter 5.

<div id="3.6.5 " class="h2-container"></div>

<span id="emerging-best-practices-for-ocean-and-coastal-climate-adaptation"></span>
=== 3.6.5 Emerging Best Practices for Ocean and Coastal Climate Adaptation ===

<div id="h2-24-siblings" class="h2-siblings"></div>

There is ''robust evidence'' that a combination of global and local solutions offers the greatest benefit in reducing climate risk ( [[#Gattuso--2018|Gattuso et al., 2018]] ; [[#Hoegh-Guldberg--2019a|Hoegh-Guldberg et al., 2019a]] ; [[#Hoegh-Guldberg--2019b|Hoegh-Guldberg et al., 2019b]] ). Ambitious and swift global mitigation offers more adaptation options and pathways to sustain ecosystems and their services (Figure 3.25). Some solutions target both mitigation and adaptation (e.g., blue carbon conservation; Cross-Chapter Box NATURAL in Chapter 2; see Box 3.4), and cross-cutting solutions simultaneously support several ocean-related sectors (e.g., area-based measures support fishing, tourism; [[#3.6.3.2|Section 3.6.3.2.1]] ) or ecosystem functions (e.g., NbS support coastal protection, biodiversity, habitat, etc.; [[#3.6.3.2.2|Section 3.6.3.2.2]] ; [[#Sala--2021|Sala et al., 2021]] ). Combined solutions also leverage a variety of existing policies and governance systems ( [[#3.6.4.3|Section 3.6.4.3]] ; [[#Duarte--2020|Duarte et al., 2020]] ) to advance climate mitigation and adaptation. Even communities that face the limits of adaptation, like those who must relocate to cope with rising seas ( [[#McMichael--2019|McMichael et al., 2019]] ; [[#Bronen--2020|Bronen et al., 2020]] ), urgently require solutions that combine scientific projections, IKLK, cultural and community values, and ways to preserve cultural identity to support planning and implementation of relocation ( [[#McMichael--2020|McMichael and Katonivualiku, 2020]] ).

Nature-based solutions are showing promising results in achieving adaptation and mitigation outcomes across marine and coastal ecosystems (Sections 3.6.3.2.1–3.6.3.2.2), but NbS have different degrees of readiness in marine ecosystems ( [[#Duarte--2020|Duarte et al., 2020]] ). Habitat restoration and recovery are highly effective in specific settings and conditions ( [[#McLeod--2019|McLeod et al., 2019]] ). Restoring and conserving vegetated coastal habitats (Sections 3.4.2.4–3.4.2.5) represent robust NbS, especially in the tropics, and particularly when paired with restoration and conservation of terrestrial ecosystems ( ''robust evidence'' ) (e.g., peatlands and forests; WGIII AR6 Chapter 7; [[#Hoegh-Guldberg--2019b|Hoegh-Guldberg et al., 2019b]] ; [[#Duarte--2020|Duarte et al., 2020]] ; [[#Griscom--2020|Griscom et al., 2020]] ). Although most of the focus on NbS efficacy has been on coastal and shelf ecosystems ( [[#3.6.3.2|Section 3.6.3.2]] ), recent advances point to an emerging role of NbS beyond coastal waters in the form of area-based management tools in marine areas beyond national jurisdiction ( [[#3.6.2.3|Section 3.6.2.3]] ; [[#Gaines--2018|Gaines et al., 2018]] ; [[#Pinsky--2018|Pinsky et al., 2018]] ; [[#Crespo--2020|Crespo et al., 2020]] ; [[#O’Leary--2020|O’Leary et al., 2020]] ; [[#Visalli--2020|Visalli et al., 2020]] ; [[#Wagner--2020|Wagner et al., 2020]] ), because sustainable fisheries and aquaculture and climate-responsive MPAs have high potential to adapt ( [[#Tittensor--2019|Tittensor et al., 2019]] ).

Adaptation efforts (Sections 3.6.3.1–3.6.3.2) have three common characteristics that facilitate implementation and success, and contribute to climate resilient development pathways (Chapter 18). First, availability of multiple types of information (e.g., monitoring, models, climate services; [[#3.6.3.3|Section 3.6.3.3]] ) exposes the magnitude and nature of the adaptation challenge. Well-developed observation and modelling capabilities ( [[#Reusch--2018|Reusch et al., 2018]] ) offer insights on climate-associated risks at different time scales ( [[#Cvitanovic--2018|Cvitanovic et al., 2018]] ; [[#Hobday--2018|Hobday et al., 2018]] ), and this facilitates adaptation within multiple areas (e.g., industries over shorter time scales, societies over longer scales) ( [[#Hobday--2018|Hobday et al., 2018]] ). Environmental data have supported building societal and political (socio-institutional) will to adopt national and subnational adaptive management principles ( [[#Hobday--2016b|Hobday et al., 2016b]] ; [[#Champion--2018|Champion et al., 2018]] ; [[#McDonald--2019|McDonald et al., 2019]] ). However, incorporating IKLK at the same time provides more diverse social–environmental insight ( [[#3.6.3|Section 3.6.3.4.1]] ; [[#Goeldner-Gianella--2019|Goeldner-Gianella et al., 2019]] ; [[#Petzold--2019|Petzold and Magnan, 2019]] ; [[#Wilson--2020b|Wilson et al., 2020b]] ). This can help align adaptation solutions with cultural values and increase their legitimacy with Indigenous and local communities (Chapter 1.3.2.3), achieving climate resilient development pathways (Chapter 18; [[#Adger--2017|Adger et al., 2017]] ; [[#Nalau--2018|Nalau et al., 2018]] ; [[#Peñaherrera-Palma--2018|Peñaherrera-Palma et al., 2018]] ; [[#Raymond-Yakoubian--2018|Raymond-Yakoubian and Daniel, 2018]] ; [[#Wamsler--2018|Wamsler and Brink, 2018]] ). Second, implementation of multiple low-risk options ( [[#Hoegh-Guldberg--2019a|Hoegh-Guldberg et al., 2019a]] ; [[#Gattuso--2021|Gattuso et al., 2021]] ) such as economic diversification ( [[#3.6.2.1|Section 3.6.2.1]] ) can provide culturally acceptable livelihood alternatives and food supplies (e.g., fishing to ecotourism and mariculture) ( [[#Froehlich--2019|Froehlich et al., 2019]] ) while also providing environmental benefits (e.g., seaweed mariculture’s potential carbon storage co-benefits) (WGIII AR6 Chapter 7; [[#Hoegh-Guldberg--2019a|Hoegh-Guldberg et al., 2019a]] ; [[#Gattuso--2021|Gattuso et al., 2021]] ). Third, inclusive governance that is well aligned to the systems at risk from climate change is fundamental for effective adaptation ( [[#Barange--2018|Barange et al., 2018]] ). Solutions implemented within polycentric governance systems ( [[#3.6.3|Section 3.6.3]] ; [[#Bellanger--2020|Bellanger et al., 2020]] ) benefit from synergies between knowledge, action and social–ecological contexts and stimulate governance responses at appropriate spatio-temporal scales ( [[#Cvitanovic--2018|Cvitanovic and Hobday, 2018]] ). Governance aligned with Indigenous structures and local structures supports successful outcomes that prioritise the concerns and rights of involved communities ( [[#3.6.3|Section 3.6.3]] ; [[#Mawyer--2018|Mawyer and Jacka, 2018]] ) and better leverages existing social organisation (i.e., network structures), learning processes and power dynamics ( [[#Barnes--2020|Barnes et al., 2020]] ).

There is an opportunity to improve current practices when developing new ocean and coastal adaptation efforts so that they routinely contain these successful characteristics and resolve technical, economic, institutional, geophysical, ecological and social constraints (Figure 3.25; [[#3.6.3.3|Section 3.6.3.3]] ; [[#IPCC--2018|IPCC, 2018]] ; [[#Singh--2020|Singh et al., 2020]] ). Enhancements are needed in human, technical and financial resources; regulatory frameworks ( [[#Ojwang--2017|Ojwang et al., 2017]] ); political support ( [[#Rosendo--2018|Rosendo et al., 2018]] ); institutional conditions and resources for fair governance ( [[#Gupta--2016|Gupta et al., 2016]] ; [[#Scobie--2018|Scobie, 2018]] ); political leadership; stakeholder engagement; multidisciplinary data availability ( [[#Gopalakrishnan--2018|Gopalakrishnan et al., 2018]] ); funding and public support for adaptation (Cross-Chapter Box FINANCE in Chapter 17; [[#Ford--2015|Ford and King, 2015]] ); and incorporating IKLK in decision making ( [[#Nalau--2018|Nalau et al., 2018]] ; [[#Jabali--2020|Jabali et al., 2020]] ; [[#Petzold--2020|Petzold et al., 2020]] ). As climate change continues to challenge ocean and coastal regions, there is ''high confidence'' associated with the benefits of developing robust, equitable adaptation strategies that incorporate scientific projections, employ portfolios of low-risk options, internalise IKLK and address social aspects of governance from international to local scales ( [[#Finkbeiner--2018|Finkbeiner et al., 2018]] ; [[#Gattuso--2018|Gattuso et al., 2018]] ; [[#Miller--2018|Miller et al., 2018]] ; [[#Raymond-Yakoubian--2018|Raymond-Yakoubian and Daniel, 2018]] ; [[#Cheung--2019|Cheung et al., 2019]] ; [[#Gattuso--2021|Gattuso et al., 2021]] ).

<div id="Acknowledgements" class="h4-container"></div>

<span id="acknowledgements"></span>
===== Acknowledgements =====

<div id="h4-29-siblings" class="h4-siblings"></div>

We acknowledge the kind contributions of Rita Erven (GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany), Miriam Seifert (Alfred Wegener Institute for Polar and Marine Research, Germany), Sebastian Rokitta (Alfred Wegener Institute for Polar and Marine Research, Germany), Amy Marie Campbell (National Oceanography Centre, Southampton/Centre for Environment, Fisheries and Aquaculture Science, UK), Mariana Castaneda-Guzman (Virginia Polytechnic Institute and State University, USA), Stephen Goult (Plymouth Marine Laboratory/National Centre for Earth Observation, UK), Josh Douglas (Plymouth Marine Laboratory, UK), Carl Reddin (Museum für Naturkunde, Berlin, Germany) and the PML Communications and Graphics Team (Plymouth Marine Laboratory, UK) who assisted in drafting figures and tables.

<div id="references" class="h1-container"></div>