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

=== 3.6.5 Emerging Best Practices for Ocean and Coastal Climate Adaptation ===

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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]] ).

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===== Acknowledgements =====

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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.

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