Editing IPCC:AR6/SROCC/Chapter-5 (section)

== Box 5.5 Coral Reef Restoration as Ocean-based Adaptation ==

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Anthropogenic global change is impacting all warm water corals and the reef structures (Section 5.2.2.3.3; IPCC 5th Assessment Report (AR5)). These impacts are rapidly increasing in scale and intensity, exposing coral reefs to enhanced degradation rates and diminishing capacities to maintain ecological resilience, to absorb disturbances, and to adapt to the changes (Box 5.1) (Graham et al., 2014 <sup>[[#fn:r1910|1910]]</sup> ; Rinkevich, 2015a <sup>[[#fn:r1911|1911]]</sup> ; Harborne et al., 2017 <sup>[[#fn:r1912|1912]]</sup> ). With the growing awareness that traditional reef conservation measures are insufficient to address climate change impacts on coral reefs (Section 5.2.2.1), adaptation interventions to enhance the resilience of coral reefs are being called for (Rinkevich, 1995 <sup>[[#fn:r1913|1913]]</sup> ; Rinkevich, 2000 <sup>[[#fn:r1914|1914]]</sup> ; Barton et al., 2017 <sup>[[#fn:r1915|1915]]</sup> ). Intervention strategies that are still at the ‘proof-of-concept’ stage, include: ‘assisted colonisation’ – actively moving species that are confined to disappearing habitats (Hoegh-Guldberg et al., 2008 <sup>[[#fn:r1916|1916]]</sup> ; Chauvenet et al., 2013 <sup>[[#fn:r1917|1917]]</sup> ); ‘assisted evolution’ – developing corals resistant to climate change via accelerated natural evolution processes (van Oppen et al., 2015 <sup>[[#fn:r1918|1918]]</sup> ); assisted coral chimerism (Rinkevich, 2019 <sup>[[#fn:r1919|1919]]</sup> ); novel coral symbiont associations (McIlroy and Coffroth, 2017 <sup>[[#fn:r1920|1920]]</sup> ); and coral microbiome manipulation (Bourne et al., 2016 <sup>[[#fn:r1921|1921]]</sup> ; Sweet and Bulling, 2017 <sup>[[#fn:r1922|1922]]</sup> ; van Oppen et al., 2017b <sup>[[#fn:r1923|1923]]</sup> ). In contrast, the ‘coral gardening’ approachs⁠—coral farmed in nurseries and transplanted using a range of tactics to increase survivability, growth rates and reproduction (Rinkevich, 2006 <sup>[[#fn:r1924|1924]]</sup> ; Rinkevich, 2014 <sup>[[#fn:r1925|1925]]</sup> )—is already in use. Other interventions that have already been implemented in some coral reefs, such as the use of artificial reefs (Ng et al., 2017) are limited in impacts, and all are also revealing considerable challenges (Riegl et al., 2011 <sup>[[#fn:r1926|1926]]</sup> ; Coles and Riegl, 2013 <sup>[[#fn:r1927|1927]]</sup> ; Ferrario et al., 2014 <sup>[[#fn:r1928|1928]]</sup> ).

Many of the alternative interventions that aim to increase the climate resilience of coral reefs involve culturing, selectively breeding and transplanting corals to enhance the adaptability of reef organisms to climate change, for example, by supporting the natural poleward range expansion of corals (West et al., 2017 <sup>[[#fn:r1933|1933]]</sup> ; Vergés et al., 2019 <sup>[[#fn:r1934|1934]]</sup> ). Advances in reef restoration techniques have been made in the last two decades (Rinkevich, 2014 <sup>[[#fn:r1935|1935]]</sup> ; Lirman and Schopmeyer, 2016 <sup>[[#fn:r1936|1936]]</sup> ), but assessments of the effectiveness of these techniques have mostly focused on the short-term feasibility of the technique (Frias-Torres and van de Geer, 2015 <sup>[[#fn:r1937|1937]]</sup> ; Lirman and Schopmeyer, 2016 <sup>[[#fn:r1938|1938]]</sup> ; Montoya Maya et al., 2016 <sup>[[#fn:r1939|1939]]</sup> ; Jacob et al., 2017 <sup>[[#fn:r1940|1940]]</sup> ; Rachmilovitz and Rinkevich, 2017 <sup>[[#fn:r1941|1941]]</sup> ), while longer-term evaluation in the context of all the pillars of sustainable development (Section 5.4.2) is limited (Rinkevich, 2015b <sup>[[#fn:r1942|1942]]</sup> ; Barton et al., 2017 <sup>[[#fn:r1943|1943]]</sup> ; Flores et al., 2017 <sup>[[#fn:r1944|1944]]</sup> ; Hein et al., 2017 <sup>[[#fn:r1945|1945]]</sup> ). These alternative interventions, primarily the coral gardening approach, face two challenges. The first is scaling up; currently, these interventions have been tested at scales of hundreds of meters, while application at larger scale is lacking (Rinkevich, 2014 <sup>[[#fn:r1946|1946]]</sup> ). The second challenge (Box 5.5, Figure 1) is the effectiveness of active reef restoration to mitigate or rehabilitate global change impacts (Shaish et al., 2010a <sup>[[#fn:r1947|1947]]</sup> ; Schopmeyer et al., 2012 <sup>[[#fn:r1948|1948]]</sup> ; Coles and Riegl, 2013 <sup>[[#fn:r1949|1949]]</sup> ; Hernández-Delgado et al., 2014 <sup>[[#fn:r1950|1950]]</sup> ; Rinkevich, 2015a <sup>[[#fn:r1951|1951]]</sup> ; Wilson and Forsyth, 2018 <sup>[[#fn:r1952|1952]]</sup> ) and whether it can keep up with rising sea levels (Perry et al., 2018 <sup>[[#fn:r1953|1953]]</sup> ), especially in low-lying ocean states.

Altogether, coral reefs of the future will not resemble those of today because of the projected decline and changes in the composition of corals and associated species in the remaining reefs (Section 5.3.4, Box 5.5 Figure 1) (Rinkevich, 2008 <sup>[[#fn:r1954|1954]]</sup> ; Ban et al., 2014 <sup>[[#fn:r1955|1955]]</sup> ) ( ''high confidence)'' . The very high vulnerability of coral reefs to warming, ocean acidification, increasing storm intensity and SLR under climate change (AR5 WG2), including enhanced bioerosion (Schönberg et al., 2017 <sup>[[#fn:r1956|1956]]</sup> ) ( ''high confidence'' ) point to the importance of considering both mitigation (Section 5.5.1) and adaptation (Section 5.3.3.6) for coral reefs. Extensive research has explored adaptation measures involving the cultivation and transplantation of corals; however, the literature contains ''limited evidence'' on the comprehensive analysis of the relative costs and benefits of these interventions across the economic, ecological, social and cultural dimensions (Bayraktarov et al., 2016 <sup>[[#fn:r1957|1957]]</sup> ; Flores et al., 2017 <sup>[[#fn:r1958|1958]]</sup> ; Linden and Rinkevich, 2017 <sup>[[#fn:r1959|1959]]</sup> ).

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<span id="box-5.5-figure-1"></span>
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'''Box 5.5, Figure 1'''

<span id="box-5.5-figure-1-coral-reef-restoration-as-an-ocean-based-adaptation-tool-to-climate-change.-the-squiggly-line-represents-non-linear-ecological-statuses-along-a-trajectory-and-five-reef-states-circles-15-in-varying-ecological-complexity-x-axis-and-service-levels-y-axis-including-two-extreme-statuses-a-pristine-versus-a-highly-degraded-state-circles-5-and"></span>
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'''Box 5.5, Figure 1 | Coral reef restoration as an ocean-based adaptation tool to climate change. The squiggly line represents non-linear ecological statuses along a trajectory and five reef states (circles 1–5; in varying ecological complexity [x-axis] and service levels [y-axis]) including two extreme statuses (a pristine versus a highly degraded state, circles 5 and […]'''
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[[File:7b53eceae95a9669a4525f9a8809f182 IPCC-SROCC-CBox_5_4.jpg]]

Box 5.5, Figure 1 | Coral reef restoration as an ocean-based adaptation tool to climate change. The squiggly line represents non-linear ecological statuses along a trajectory and five reef states (circles 1–5; in varying ecological complexity [x-axis] and service levels [y-axis]) including two extreme statuses (a pristine versus a highly degraded state, circles 5 and 1, respectively). Two ‘restored reef-state’ scenarios (circles 2, 3), lead to the state of the restored ‘reef of tomorrow’ (circle 4). The route from the state of the ‘reef of tomorrow’ (circle 4) to a pristine state (circle 5) is doubtful (the question mark) and is still at a theoretical level. The routes from the two ‘restored reef-state’ scenarios to the ‘reef of tomorrow’ are under investigations (the question marks). Based on Rinkevich (2014) (Figure 1). A–C represent different reef statuses. A = a denuded knoll at the Dekel Beach, Eilat, Israel before reef transplantation (November 2005; Photo: Y. Horoszowski-Fridman); B = the same knoll, restored (June 2016; photo by Shai Shafir). More than 300 nursery-grown colonies of 7 coral species were transplanted during three successive transplantations (years 2005, 2007, 2009). In 2016 the knoll was surrounded by reef inhabiting schools of fish. C = a pristine reef, not existing under current and anticipated reef conditions. Restoration scenarios are developed along paths from a degraded reef (low ecological complexity, minimal reef services) toward a healthy ‘reef of tomorrow’, passing through two restored reef states that are impacted by climate change (Shaish et al. 2010a <sup>[[#fn:r1929|1929]]</sup> ; Schopmeyer et al. 2012 <sup>[[#fn:r1930|1930]]</sup> ; Hernández-Delgado et al. 2014 <sup>[[#fn:r1931|1931]]</sup> ; Rinkevich, 2015a <sup>[[#fn:r1932|1932]]</sup> ). The employment of ecological engineering approaches may help in moving the ecological states from either restored reef to the ‘reef of tomorrow’ status (medium confidence).

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<span id="adaptation-in-mangroves-and-other-coastal-ecosystems"></span>
===== 5.5.2.1.3 Adaptation in mangroves and other coastal ecosystems =====

Mangroves provide significant ecosystem services, including localised coastal protection from extreme storm events (Section 5.4.1), supporting services through increased sedimentation rates (Hayden and Granek, 2015 <sup>[[#fn:r1960|1960]]</sup> ) and provisioning services for local communities, for example, habitats for nurseries to support fisheries. Mangroves provide limited carbon mitigation, in terms of global emissions reduction, and substantial job creation (Table 5.7) co-benefits (for example through Reducing Emissions from Deforestation and Forest Degradation programmes) when managed properly (Section 5.4.1, 5.5.1.1), and there is evidence of their value in supporting aquaculture and fishery initiatives (Huxham et al., 2015 <sup>[[#fn:r1961|1961]]</sup> ; Ahmed and Glaser, 2016a <sup>[[#fn:r1962|1962]]</sup> ).

Mangrove EbA responses most commonly reported included ecosystem restoration (Sierra-Correa and Cantera Kintz, 2015 <sup>[[#fn:r1963|1963]]</sup> ; Romañach et al., 2018 <sup>[[#fn:r1964|1964]]</sup> ) and management such as mangroves re-planting through community participation programmes (Nanlohy et al., 2015 <sup>[[#fn:r1965|1965]]</sup> ; Nguyen et al., 2017 <sup>[[#fn:r1966|1966]]</sup> ; Triyanti et al., 2017 <sup>[[#fn:r1967|1967]]</sup> ). Mangrove EbA has been reported to provide multiple co-benefits in terms of improvement in support for coastal physical processes, including: shoreline stabilisation (Hayden and Granek, 2015 <sup>[[#fn:r1968|1968]]</sup> ; Nanlohy et al., 2015 <sup>[[#fn:r1969|1969]]</sup> ); ecological functioning (Sierra-Correa and Cantera Kintz, 2015 <sup>[[#fn:r1970|1970]]</sup> ; Miller et al., 2017 <sup>[[#fn:r1971|1971]]</sup> ) with improved ecosystem services (Alongi, 2015 <sup>[[#fn:r1972|1972]]</sup> ; Nanlohy et al., 2015 <sup>[[#fn:r1973|1973]]</sup> ; Palacios and Cantera, 2017 <sup>[[#fn:r1974|1974]]</sup> ); carbon mitigation (5.5.1.1); supporting livelihoods (Nanlohy et al., 2015 <sup>[[#fn:r1975|1975]]</sup> ; Nguyen et al., 2017 <sup>[[#fn:r1976|1976]]</sup> ); and reductions in coastal infrastructure damage and community vulnerability to climate change impacts. Managed retreat to counter coastal squeeze (Section 5.3) through improved governance, creation of finance and land use planning can allow mangroves to move up the shoreline contour or down the latitudinal gradient (Sierra-Correa and Cantera Kintz, 2015 <sup>[[#fn:r1977|1977]]</sup> ; Ward et al., 2016 <sup>[[#fn:r1978|1978]]</sup> ; Romañach et al., 2018 <sup>[[#fn:r1979|1979]]</sup> ). Therefore, mangrove EbA responses can strengthen coastal ecosystem services through shoreline stabilisation and provide multiple co-benefits for coastal communities, like job creation and improved access to ecosystem services ( ''high confidence'' ).

There are, however, examples where community mangrove restoration projects have resulted in maladaptive outcomes, in which the resulting ecosystem degradation could not provide the ecosystem services required (Nguyen et al., 2017 <sup>[[#fn:r1980|1980]]</sup> ; Romañach et al., 2018 <sup>[[#fn:r1981|1981]]</sup> ). Such maladaptation can be a result of poor governance processes or a lack of community compliance with restoration plans. These examples emphasise the value of designing effective governance to implement adaptation responses with broad community participation to improve the climate risk reduction outcomes and co-benefits (Sierra-Correa and Cantera Kintz, 2015 <sup>[[#fn:r1982|1982]]</sup> ; Nguyen et al., 2017 <sup>[[#fn:r1983|1983]]</sup> ) ( ''medium evidence, high agreement'' ).

Mangrove and other coastal ecosystems restoration and management can be applied through reducing non-climatic hazards (Gilman et al., 2008 <sup>[[#fn:r1984|1984]]</sup> ; Ataur Rahman and Rahman, 2015 <sup>[[#fn:r1985|1985]]</sup> ; Sierra-Correa and Cantera Kintz, 2015 <sup>[[#fn:r1986|1986]]</sup> ; Ahmed and Glaser, 2016a <sup>[[#fn:r1987|1987]]</sup> ; Nguyen et al., 2017 <sup>[[#fn:r1988|1988]]</sup> ; Romañach et al., 2018 <sup>[[#fn:r1989|1989]]</sup> ). Coastal and catchment development, including wetland transformation and degradation (Miloshis and Fairfield, 2015 <sup>[[#fn:r1990|1990]]</sup> ; Schaeffer-Novelli et al., 2016 <sup>[[#fn:r1991|1991]]</sup> ; Watson et al., 2017a <sup>[[#fn:r1992|1992]]</sup> ; Schuerch et al., 2018 <sup>[[#fn:r1993|1993]]</sup> ), the disruption of physical processes impacting sedimentation rates (Watson et al., 2017a <sup>[[#fn:r1994|1994]]</sup> ) and coastal squeeze compound coastal climate change impacts like erosion, flooding and saltwater intrusion (Ondiviela et al., 2014 <sup>[[#fn:r1995|1995]]</sup> ; Miloshis and Fairfield, 2015 <sup>[[#fn:r1996|1996]]</sup> ; Schaeffer-Novelli et al., 2016 <sup>[[#fn:r1997|1997]]</sup> ; Wigand et al., 2017 <sup>[[#fn:r1998|1998]]</sup> ) (Section 5.3). This reduces the ability of these ecosystems to provide protection from wave and storm impacts, whilst positive feedbacks may occur that cause a net release of carbon into the atmosphere, for example, in salt marshes (Wong et al., 2014a <sup>[[#fn:r1999|1999]]</sup> ) (Section 5.4.1). In some cases, effective interventions requires management at a broad spatial scale that includes a variety of ecosystems, for example, including ecosystems like mussel beds on the seaward side of seagrass beds to reduce wave energy and erosion (Ondiviela et al., 2014 <sup>[[#fn:r2000|2000]]</sup> ). Where sediment accretion matches the SLR rate, wetlands and salt marshes provide effective coastal protection and other important ecosystem services ( ''high confidence'' ).

Coastal dune systems are widely transformed globally. Human disturbance and the limited stabilising ability of dune vegetation are key causes of degradation (Onaka et al., 2015 <sup>[[#fn:r2001|2001]]</sup> ; Ranasinghe, 2016 <sup>[[#fn:r2002|2002]]</sup> ; MacDonald et al., 2017 <sup>[[#fn:r2003|2003]]</sup> ; Pranzini, 2017 <sup>[[#fn:r2004|2004]]</sup> ; Salgado and Martinez, 2017 <sup>[[#fn:r2005|2005]]</sup> ; Vikolainen et al., 2017 <sup>[[#fn:r2006|2006]]</sup> ; Gracia et al., 2018 <sup>[[#fn:r2007|2007]]</sup> ), while restoration efforts can be supported by both hard (Sutton-Grier et al., 2015 <sup>[[#fn:r2008|2008]]</sup> ; Pranzini, 2017 <sup>[[#fn:r2009|2009]]</sup> ) and soft (Sutton-Grier et al., 2015 <sup>[[#fn:r2010|2010]]</sup> ; Vikolainen et al., 2017 <sup>[[#fn:r2011|2011]]</sup> ) engineering responses. Reduced coastal erosion (Sánchez-Arcilla et al., 2016 <sup>[[#fn:r2012|2012]]</sup> ; Goreau and Prong, 2017 <sup>[[#fn:r2013|2013]]</sup> ; Vikolainen et al., 2017 <sup>[[#fn:r2014|2014]]</sup> ; Carro, 2018 <sup>[[#fn:r2015|2015]]</sup> ; Gracia et al., 2018 <sup>[[#fn:r2016|2016]]</sup> ) and flood risk (Onaka et al., 2015 <sup>[[#fn:r2017|2017]]</sup> ; MacDonald et al., 2017 <sup>[[#fn:r2018|2018]]</sup> ; Nehren et al., 2017 <sup>[[#fn:r2019|2019]]</sup> ) through maintaining dunes as natural buffers against wave energy (Nehren et al., 2017 <sup>[[#fn:r2020|2020]]</sup> ) can increase resilience to climate change impacts (Sutton-Grier et al., 2015 <sup>[[#fn:r2021|2021]]</sup> ; Magnan and Duvat, 2018 <sup>[[#fn:r2022|2022]]</sup> ). Engineered responses and sand replenishment are considered complementary approaches (Onaka et al., 2015 <sup>[[#fn:r2023|2023]]</sup> ; Martínez et al., 2017 <sup>[[#fn:r2024|2024]]</sup> ). Section 4.4.4.1 provides an overview of sediment-based adaptation response measures, including cost estimates for beach nourishment and dune maintenance, a discussion of co-benefits and drawbacks of combining hard and soft infrastructure measures, and challenges with sourcing sediment for beach replenishment. In some cases dune restoration and sand replenishment projects have not been successful, due to fire damage (Shumack and Hesse, 2017 <sup>[[#fn:r2025|2025]]</sup> ) or the rapid loss of sand within replenishment schemes due to coastal processes and stakeholder rejection of adaptation activities (Pranzini, 2017 <sup>[[#fn:r2026|2026]]</sup> ). Coastal dune restoration and beach replenishment are effective responses against coastal erosion and flooding, where sufficient materials and space to implement are available ( ''medium confidence'' ).

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<span id="ecosystem-based-adaptation-1"></span>
===== 5.5.2.1.4 Ecosystem-based adaptation =====

There is a growing body of literature regarding the effectiveness and economics of EbA. In addition to building resilience to climate change, EbA is expected to bring a wide range of co-benefits that include increasing ecological complexity, with multiple ecosystem services, and other economic co-benefits (Perkins et al., 2015 <sup>[[#fn:r2027|2027]]</sup> ; Perry, 2015 <sup>[[#fn:r2028|2028]]</sup> ; Moosavi, 2017 <sup>[[#fn:r2029|2029]]</sup> ; Scarano, 2017 <sup>[[#fn:r2030|2030]]</sup> ). The cost-effectiveness of EbA approaches varies between marine ecosystem types; for example, coral reefs (Perkins et al., 2015 <sup>[[#fn:r2031|2031]]</sup> ; Beetham et al., 2017 <sup>[[#fn:r2032|2032]]</sup> ; Elliff and Silva, 2017 <sup>[[#fn:r2033|2033]]</sup> ; Beck et al., 2018 <sup>[[#fn:r2034|2034]]</sup> ; Comte and Pendleton, 2018 <sup>[[#fn:r2035|2035]]</sup> ) and salt-marshes (Ondiviela et al., 2014 <sup>[[#fn:r2036|2036]]</sup> ; Miloshis and Fairfield, 2015 <sup>[[#fn:r2037|2037]]</sup> ; Schaeffer-Novelli et al., 2016 <sup>[[#fn:r2038|2038]]</sup> ; Wigand et al., 2017 <sup>[[#fn:r2039|2039]]</sup> ) performed best at reducing wave heights, whilst salt marshes and mangroves were two to five times cheaper than submerged breakwaters for wave heights of less than half a meter. Although low regrets, win-win approaches like EbA are supported in the literature (Watkiss et al., 2014 <sup>[[#fn:r2040|2040]]</sup> ; Barange et al. 2018 <sup>[[#fn:r2041|2041]]</sup> ), syntheses of experience from context-specific practical implementation of EbA and assessment of their cost-effectiveness are limited (Narayan et al., 2016). Therefore, EbA can be a cost-effective approach for securing climate change-related ecosystem services with multiple co-benefits ( ''medium evidence, high agreement'' ).

The application of EbA approaches can be more effective when incorporating local knowledge and Indigenous knowledge and cultural practices into adaptation responses (Ataur Rahman and Rahman, 2015 <sup>[[#fn:r2042|2042]]</sup> ; Perkins et al., 2015 <sup>[[#fn:r2043|2043]]</sup> ; Sutton-Grier et al., 2015 <sup>[[#fn:r2044|2044]]</sup> ; Sánchez-Arcilla et al., 2016 <sup>[[#fn:r2045|2045]]</sup> ; van der Nat et al., 2016 <sup>[[#fn:r2046|2046]]</sup> ). The application of synergistic combinations of adaptation responses in multiple ecosystems can provide a range of co-benefits, and this approach is strengthened when combined with socioinstitutional approaches (Kochnower et al., 2015 <sup>[[#fn:r2047|2047]]</sup> ; MacDonald et al., 2017 <sup>[[#fn:r2048|2048]]</sup> ). Research to improve and refine EbA approaches and increase their specificity to local context is important for their effectiveness in reducing climate risks and generating co-benefits (Sutton-Grier et al., 2015 <sup>[[#fn:r2049|2049]]</sup> ). Conversely, a lack of inclusion of local communities and economic undervaluation of specific coastal and marine ecosystems, compounded by gaps in scientific data, can undermine the potential effectiveness of EbA approaches (Perkins et al., 2015 <sup>[[#fn:r2050|2050]]</sup> ; Hernández-González et al.; Narayan et al., 2016 <sup>[[#fn:r2051|2051]]</sup> ; Roberts et al., 2017 <sup>[[#fn:r2052|2052]]</sup> ).

Despite the abundance of EbA examples in the literature, knowledge gaps pertaining to their implementation and limitations remain. Developing this literature could help with understanding context specific application of EbA and improve their effectiveness ( ''medium confidence'' ).

<div id="section-5-5-2-2human-systems"></div>

<span id="human-systems"></span>
==== 5.5.2.2 Human Systems ====

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Many of the world’s great cities lie within the coastal region, and climate change impacts put these cities, their inhabitants and their economic activities at risk. Section 5.5.2.2 assesses the impacts of climate change, adaptation response and benefits upon human systems, including coastal communities, built infrastructure, fisheries and aquaculture, coastal tourism, government and health systems. Table 5.8 provides a summary of the assessment, with citations provided in the Supplementary Material Table 5.7.

Poorly planned (Ataur Rahman and Rahman, 2015), located (Abedin et al., 2014; Betzold and Mohamed, 2017; Linkon, 2018) and managed urban settlements or human systems, driven by growing human coastal populations (Perkins et al., 2015; Moosavi, 2017; Carter, 2018) and compounded by the disruption of coastal and catchment physical processes (Nagy et al., 2014; Broto et al., 2015; Marfai et al., 2015; Kabisch et al., 2017) and pollution (Zikra et al., 2015; Peng et al., 2017) are major human drivers of change compounding the impacts of climate change.

Coastal communities, built infrastructure and fisheries and aquaculture (Table 5.8) are likely to be significantly affected through the disruption of coastal physical processes (DasGupta and Shaw, 2015; Betzold and Mohamed, 2017; Hagedoorn et al., 2019) leading to coastal erosion, flooding, salt water intrusion and built infrastructure damage (Dhar and Khirfan, 2016; Hobday et al., 2016a; Jurjonas and Seekamp, 2018) ( ''robust evidence, high agreement'' ). Ecosystem degradation and biodiversity loss will further compound impacts in coastal communities and fisheries and aquaculture (Ataur Rahman and Rahman, 2015; Petzold and Ratter, 2015; Dhar and Khirfan, 2016), with sub-lethal species impacts like changes in the productivity and distribution of fisheries target species reported for the latter (Gourlie et al., 2018; Nursey-Bray et al., 2018; Pinsky et al., 2018) ( ''high confidence'' ). This is likely to result in decreased access to ecosystem services (Asch et al., 2018; Cheung et al., 2018b; Finkbeiner et al., 2018) ( ''medium evidence, high agreement'' ), local declines in agriculture and fisheries (Cvitanovic et al., 2016; Faraco et al., 2016) ( ''high confidence'' ) and livelihood impacts (Harkes et al., 2015; Busch et al., 2016; Valmonte-Santos et al., 2016) ( ''high confidence'' ) in coastal communities and fisheries and aquaculture, particularly increased food insecurity and health risk in the latter ( ''high confidence'' ). These livelihood impacts are likely to increase social vulnerability ( ''high confidence'' ). Businesses within coastal communities are likely to experience disruptions and losses ( ''robust evidence, high agreement'' ).

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<span id="coastal-communities"></span>
===== 5.5.2.2.1 Coastal communities =====

This section describes a range of adaptation responses reported at the level of the individual or community. Hard engineering responses included small scale hard infrastructure coastal defenses (Betzold and Mohamed, 2017; Jamero et al., 2018), design responses at the household level (Ataur Rahman and Rahman, 2015; Linkon, 2018) and retreat (Marfai et al., 2015). Ecosystem restoration and protection, particularly in mangroves (Ataur Rahman and Rahman, 2015; Bennett et al., 2016; Jamero et al., 2018; Hagedoorn et al., 2019) through community participation programmes (Barbier, 2015; Petzold and Ratter, 2015; Bennett et al., 2016; Dhar and Khirfan, 2016; Jamero et al., 2018) was strongly supported in the literature as a means to improve access to or storage of natural resources ( ''medium evidence, high agreement'' ).

<span id="table-5.8"></span>
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'''Table 5.8'''
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Summary of reported Adaptation responses (A), the Impacts (I) they aimed to address, and the expected Benefits (B) in human systems within Physical, Ecological, Social, Governance, Economic and Knowledge categories. Legend: a + sign indicates ''robust evidence'' , a triangle indicates ''medium evidence'' and an underline indicates ''limited evidence'' . Dark blue cells indicate ''high agreement'' , blue indicates ''medium agreement'' and light blue indicates either ''low agreement'' (denoted by presence of a sign) if sufficient papers were reviewed for an assessment or no assessment (if less than three papers were assessed per cell). Papers used for this assessment can be found in SM5.6.

[[File:45deab12541685d2376343e8da1e06ee table5.8-a.png]]<br />
[[File:bc37cad80eb1a60e368fa87016caa777 table5.8-b.png]]<br />
[[File:6f5e3a87b2abe433837f028526abd908 table5.8-c.png]]<br />
[[File:2d719840af122114e3ade0243a4cb455 table5.8-d.png]]<br />
[[File:087dbd6264aa15d76f86ce8f67a6fe29 table5.8-e.png]]<br />
[[File:42bfe550b404d5e9121c160bed4261a7 table5.8-f.png]]

Social responses include increasing climate change awareness, improving participatory decision making through bottom-up approaches, community organisation for action and engagements with local management authorities (Dutra et al., 2015; Tapsuwan and Rongrongmuang, 2015; Galappaththi et al., 2017; Ray et al., 2017; Cinner et al., 2018; Hagedoorn et al., 2019). In coastal communities, and indeed in most other sectors, despite consensus on the importance of cooperation in tackling climate change (Elrick-Barr et al., 2016), adaptation progress may be hampered by competing economic interests and worldviews (Hamilton and Safford, 2015), which can be compounded by limited climate change knowledge (Nanlohy et al., 2015). Factors like home ownership and a general future planning ability support resilience (Elrick-Barr et al., 2016). Climate change adaptation capacity is shaped by historical path dependencies, local context and international linkages, while action is shaped by science, research partnerships and citizen participation (Hernández-Delgado, 2015; Sheller and León, 2016). Locally context-specific data to guide appropriate adaptation response remains a knowledge gap (Abedin and Shaw, 2015; Hobday et al., 2015; Lirman and Schopmeyer, 2016; Williams et al., 2016)

Coastal and oceanic adaptation responses are greatly complicated by the presence of competing interests (either between user groups, communities or nations), where considerations other than climate change need to be incorporated into cooperation agreements and policy (Wong et al., 2014a). The deployment of either built or natural protection systems, or adopting a ‘wait and see’ approach, is subject to the social acceptance of these approaches in communities (Poumadère et al., 2015; Sherren et al., 2016; Torabi et al., 2018). Similarly, the willingness to move away from climate change impacted zones is dependent upon a range of other socioeconomic factors like age, access to resources and crime (Bukvic et al.; Rulleau and Rey-Valette, 2017). Adaptation to climate change includes a range of non-climatic and social variables that complicate implementation of adaptation plans ( ''robust evidence, high agreement'' ).

Improving community participation and integrating knowledge systems (local, traditional and scientific) supports coastal community adaptation responses ( ''high confidence'' ), providing improved co-production of knowledge ( ''medium evidence, high agreement'' ), improved community awareness ( ''medium evidence, medium agreement'' ) and better-informed, more cohesive coastal communities ( ''limited evidence, medium agreement'' ).

<!-- END IMG -->
<div id="section-5-5-2-2human-systems-block-3"></div>

<span id="built-infrastructure"></span>
===== 5.5.2.2.2 Built infrastructure =====

Built infrastructure impacts are most frequently addressed through hard engineering approaches including: construction of groins, seawalls, revetments, gabions and breakwaters (Friedrich and Kretzinger, 2012; Vikolainen et al., 2017); improving drainage and raising the height of roadways and other fixed-location infrastructure (Perkins et al., 2015; Becker et al., 2016; Colin et al., 2016; Asadabadi and Miller-Hooks, 2017; Brown et al., 2018a); erosion control systems (Jeong et al., 2014); and the relocation of infrastructure (Friedrich and Kretzinger, 2012; Colin et al., 2016). Nature-based responses are increasingly being reported as complementary and supporting tools (van der Nat et al., 2016; Kabisch et al., 2017; Gracia et al., 2018) using ecological engineering (Perkins et al., 2015; van der Nat et al., 2016; Moosavi, 2017) combined with innovative construction strategies (Moosavi, 2017).

When implemented together, hard and soft engineering responses provide social (Gracia et al., 2018, Martínez et al., 2018; Woodruff, 2018) and ecological (Perkins et al., 2015; van der Nat et al., 2016; Gracia et al., 2018) co-benefits with reduced damage costs (Jeong et al., 2014). Constraints on implementation include the space and extra cost required by ecological infrastructure, sub-optimal performance when impacted by natural physical processes that are disrupted (Gracia et al., 2018) or restrictions associated with governance (Vikolainen et al., 2017). Adaptation planning including local communities can improve implementation and help fill knowledge gaps (Kaja and Mellic, 2017; Moosavi, 2017; Martínez et al., 2018; Mikellidou et al., 2018). Benefits include increased resilience in coastal infrastructure and better informed decision making tools ( ''medium confidence'' ),

<div id="section-5-5-2-2human-systems-block-4"></div>

<span id="adaptation-in-fisheries-and-aquaculture"></span>
===== 5.5.2.2.3 Adaptation in fisheries and aquaculture =====

Sixty percent of assessed species are projected to be at high risk from both overfishing and climate change by 2050 (RCP8.5), particularly tropical and subtropical species (Cheung et al., 2018b). Overfishing is one of the most important non-climatic drivers affecting the sustainability of fisheries (Islam et al., 2013; Heenan et al., 2015; Faraco et al., 2016; Dasgupta et al., 2017; Cheung et al., 2018b; Harvey et al., 2018). Pursuing sustainable fisheries practices under a low emissions scenario would decrease risk by 63%. This highlights the importance of effective fisheries management (Gaines et al., 2018). Eliminating overfishing would, however, require reducing current levels of fishing effort, with a potential short-term reduction in catches impacting livelihoods and the food security of coastal communities (Hobday et al., 2015; Dey et al., 2016; Rosegrant et al., 2016; Campbell, 2017; Finkbeiner et al., 2018). Despite consensus on the effectiveness of eliminating overfishing in supporting climate change adaptation in fisheries ( ''robust evidence, high agreement)'' , successful adaptation outcomes remain aspirational.

Range shifts under ocean warming (Section 5.2.3) will alter the distribution of fish stocks across political boundaries, thus demand for transboundary fisheries management will increase. Redistribution of transboundary fish stocks between countries (Ho et al., 2016; Gourlie et al., 2017; Asch et al., 2018) could destabilise existing international fisheries agreements and increase the risk of international conflicts (Section 5.4.2). Adaptation to reduce risks in international fisheries management could involve improving planning for cooperative management between countries informed by reliable predictions (Payne et al., 2017) and projections (Pinsky et al., 2018) of species shifts and associated uncertainties. Cooperative international fisheries arrangements, such as flexible fishing effort allocation and adaptive frameworks (Colburn et al., 2016; Cvitanovic et al., 2016; Faraco et al., 2016) may also improve the robustness of fisheries management (Miller et al., 2013). Thus, although range shifts pose significant challenges to transboundary fisheries management, proactive planning and adjustment of fisheries management arrangements, informed by scientific projections, could help improve adaptive capacity ( ''medium confidence'' ). The effectiveness of incorporating MPAs as an adaptation strategy to climate change can be improved by considering climate impacts in the design of MPAs ( ''medium, high agreement'' ).

Improving integrated coastal management and better planning for MPAs by incorporating projected shifting biological communities, abundance and life history changes (Álvarez-Romero et al., 2018) due to climate change could contribute towards improved fisheries adaptive management by, for example, increasing resilience of habitats, providing refugia for species with shifting distributions and by conserving biodiversity (Faraco et al., 2016; Valmonte-Santos et al., 2016; Dasgupta et al., 2017; Le Cornu et al., 2017; Roberts et al., 2017; Asch et al., 2018; Cheung et al., 2018b; Harvey et al., 2018; Jones et al., 2018; O’Leary and Roberts, 2018) (Sections 5.2.3, 5.3, 5.4.1), but MPAs may also reduce access to subsistence fishers, increasing their vulnerability to food insecurity (Bennett et al., 2016; Faraco et al., 2016). The global area of MPAs is rapidly increasing towards the United Nations’ target of 10% of the global ocean. While this is encouraging, it is estimated that only 2% of the ocean is well enough managed, as described in (Edgar et al., 2014), to meet conservation goals (Sala et al., 2018). Improving the implementation and coordination of policies, and improving integrated coastal management and MPAs have emerged in the literature as important adaptation governance responses ( ''robust evidence, medium agreement'' ).

Governance responses to support adaptation in fisheries communities include conducting vulnerability assessments, improving monitoring of ecosystem indicators and evaluating management strategies (Himes-Cornell and Kasperski, 2015b; Busch et al., 2016). Socioeconomic factors like access to alternative income, mobility, gender and religion collectively shape a community’s adaptation response (Arroyo Mina et al., 2016). In West Africa, the industrial fishery response to climate change induced reductions in landings was the expansion of fishing grounds, which increased operational costs (Belhabib et al., 2016). This response is not available to artisanal and local fishing communities, who are considered highly vulnerable (Kais and Islam, 2017). Access to finance to support these communities or their governments could help them reach novel fishing grounds, and, therefore, potentially reduce their vulnerability. Food security linked to fisheries depends on stock recovery, but also on access to and distribution of the harvest, as well as gender considerations (Béné et al., 2015). Hence, granting preferential access to dependent coastal communities should be considered in examining policy options. Other adaptation responses include improved fishing gear and technology, use of fish aggregating devices and uptake of insurance products (Zougmoré et al., 2016) [see Barange et al. (2018) for a summary of possible adaptation responses]. Community response as a part of climate change adaptation for local fisheries is an important element in assessing adaptive capacity ( ''medium evidence, good agreement'' ),

Fisheries management strategies depend heavily upon data collection and monitoring systems. These include the accuracy of data collected in respect of predicting environmental conditions, over time scales from months to decades (Dunstan et al., 2018), effective monitoring and evaluative mechanisms (Le Cornu et al., 2017; Gourlie et al., 2018), controlling for aspects of fish population dynamics like recruitment success and fish movement (Mace, 2001). Seasonal to decadal  [https://www.sciencedirect.com/topics/earth-and-planetary-sciences/climate-prediction climate prediction]  systems allow for skillful predictions of climate variables relevant to fisheries management strategies (Hobday et al., 2016b; Payne et al., 2017). Effective fisheries adaptation responses will require knowledge development including better monitoring, modelling and improving decision support frameworks ( ''medium evidence, high agreement'' ) and improving forecasting and early warning systems ( ''medium evidence, medium agreement'' ).

In considering a participatory decision making approach for fisheries management that responds to climate change, Heenan et al. (2015){Heenan,  #274;Heenan, 2015 #274} provided a number of key elements that contribute towards a successful outcome. These include expert knowledge of climate change threats to fish habitats, stocks and landings, the necessity of transdisciplinary collaboration and stakeholder participation, broadening the range and scope of fisheries systems and increased commitment of resources and capacity. This was considered in the context of the ability of developing countries to sustainably exploit fisheries resources and related ecosystems. More research is required on socioecological responses to climate change impacts on fishery communities, including such aspect as like risk reduction, adaptive capacity through knowledge attainment and social networks, developing alternative skills and participatory approaches to decision making (Dubey et al., 2017; Shaffril et al., 2017; Finkbeiner et al., 2018). Important fisheries adaptation responses in relation to knowledge management include improving participatory processes ( ''robust evidence, high agreement'' ), integrating knowledge systems ( ''medium evidence, high agreement'' ), and stakeholder identification, outreach and education ( ''medium evidence, medium agreement'' ). Ecosystem-based adaptation, community participatory programmes, and improving agricultural and fisheries practices are very strongly supported in the literature ( ''high confidence'' ).

Less still is known about how climate change will affect the deep oceans and its fisheries (Section 5.2.3 and 5.2.4), the vulnerability of its habitats to fishing disturbance and future effects on resources not currently harvested (FAO, 2019). Johnson et al. (2019) concluded that in a 20- to 50-year timeframe, the effectiveness of virtually all north Atlantic deep water and open ocean area-based management tools can be expected to be affected. They concluded that more precise and detailed oceanographic data are needed to determine possible refugia, and more research on adaptation and resilience in the deep sea is needed to predict ecosystem response times.

As with fisheries, community- and ecosystem-based adaptation responses, an integrated coastal management framework is considered useful for planning for anticipated challenges for aquaculture (Ahmed and Diana, 2015b; Barange et al. 2018). Where ''in situ'' adaptation is not possible, translocation and polyculture (Ahmed and Diana, 2015a; Bunting et al., 2017) have been suggested as appropriate responses, but this would suit commercial rather than subsistence interests. Policy, economic, knowledge and other types of support are required to build socioecological resilience of vulnerable coastal aquaculture communities (Harkes et al., 2015; Bunting et al., 2017; Rodríguez-Rodríguez and Bande Ramudo, 2017), which requires a deep understanding of the nature of stressors and a commitment for collective action (Galappaththi et al., 2017). Climate resilient pathway development (see Cross-Chapter Box 2) is considered a useful framework for Sri Lankan shrimp aquaculture (Harkes et al., 2015). Another example of successful aquaculture adaptation is the employment of near real time monitoring technology to track the carbonate chemistry in water to reduce bio-erosion in shellfish from acidification (Barton et al., 2015; Cooley et al., 2016). Numerous adaptation responses are available for aquaculture, but some options, like translocation and technological responses may not be available to subsistence-based communities ( ''medium evidence'' ).

An example of eco-engineering-based adaptation option in seaweed aquaculture under climate change is

artificial upwelling, as shown by experiments and observations. Artificial upwelling powered by green energy (solar, wind, wave or tidal energy) to seaweeds (Jiao et al., 2014b; Zhang et al., 2015; Pan and Schimel, 2016) can moderate the amount of deep water upwelled to the euphotic zone to just meet the demands of nutrients and DIC by the seaweed for photosynthesis, while avoiding the acidification and hypoxia that often occur in natural upwelling systems (Jiao et al., 2018a; Jiao et al., 2018b) ( ''high confidence'' ). Such artificial upwelling based eco-engineering may also gradually release the ‘bomb’ of rich nutrients and hypoxia in the bottom water, which could otherwise breakout following storms (Daneri et al., 2012) ( ''high confidence'' ).

<div id="section-5-5-2-2human-systems-block-5"></div>

<span id="coastal-tourism"></span>
===== 5.5.2.3.4 Coastal tourism =====

The coastal tourism economic sector is highly sensitive to climate change. Tourism response, in terms of mitigating carbon emissions and adapting to climate change impacts, are assessed here. Coastal tourism is likely to be impacted by ecosystem degradation and loss ( ''limited evidence, medium agreement'' ), which underscores the importance of nature-based tourism. An example of coastal erosion in Latin America illustrates this, whereby SLR interacting with non-climate change impacts including sand mining, inappropriate development and habitat destruction (e.g., mangroves), resulted in declines in tourism (Rangel-Buitrago et al., 2015). The management recommendation was appropriate legislation with a marine spatial planning emphasis, enforcement, sustainable funding mechanisms and support networks for decision making.

Climate change impacts upon tourism are nuanced and not restricted to just physical impacts on tourism establishments (Biggs et al., 2015). Understanding the drivers of tourist choices could help support adaptation in the industry through marine spatial planning processes (Papageorgiou, 2016). For example, in an survey ranking mitigation and adaptation responses in Greece, tourists prioritised rational energy use, energy efficiency and water saving measures (Michailidou et al., 2016b). Location specific information of tourist choices could help shape local industries. In one example from the Thailand dive industry, climate change adaptation responses of participants were reported to be based on misconceptions about climate change and personal observations (Tapsuwan and Rongrongmuang, 2015). To improve community-based adaptation, efforts aimed at broadening the level of awareness about climate change could improve decision making processes (Tapsuwan and Rongrongmuang, 2015). Tourist behaviour is shaped by changing ocean physical processes and degrading ecosystems at tourist destinations, which drive destination changes, economic flows and market share adjustments. (Bujosa et al., 2015; De Urioste-Stone et al., 2016).

It is very likely that climate change will have direct and nuanced impacts upon coastal tourism. Improving decision support frameworks ( ''low evidence, medium agreement'' ) for better-informed decision making tools could contribute towards increasing resilience in coastal tourism ( ''low evidence, limited agreement'' ).

<div id="section-5-5-2-2human-systems-block-6"></div>

<span id="government-responses"></span>
===== 5.5.2.2.5 Government responses =====

Government responses included adopting and mainstreaming sustainability policies, including investments and policies for climate change (Aylett, 2015; Buurman and Babovic, 2016) and applying the precautionary principle in the absence of precise scientific guidance (Johnson et al., 2018). Developing adequate governance and management systems (Johnson et al., 2018), strengthening capacity (Gallo et al., 2017; Paterson et al., 2017), increasing cooperation (Nunn et al., 2014; Gormley et al., 2015) and aligning policies of local authorities (Porter et al., 2015; Gallo et al., 2017; Rosendo et al., 2018) could help to improve implementation (Sano et al., 2015; Elsharouny, 2016). This includes planning for MPAs and improving integrated coastal management (Abelshausen et al., 2015; Roberts et al., 2017; Rosendo et al., 2018) by incorporating climate science (Hopkins et al., 2016; Johnson et al., 2018) to optimise priority marine habitats (Gormley et al., 2015; Jones et al., 2018). An advantage of integrated coastal management is that it helps manage the interactions between multiple climate and non-climatic drivers of coastal ecosystems and sectors. Incorporating stakeholder participation with local knowledge and Indigenous knowledge could help to reduce the risk of maladaptation, and increase buy-in for implementation (Serrao-Neumann et al., 2013). Improving participatory processes strengthens governance decision making and flexible risk management processes (Gerkensmeier and Ratter, 2018; Rosendo et al., 2018), while stimulating bi-directional knowledge flow and improving social learning (Abelshausen et al., 2015).

Technology for environmental monitoring, for example using drones (Clark, 2017), web-based coastal information systems (Mayerle et al., 2016; Newell and Canessa, 2017), the Internet of Things and machine learning solutions promise to improve the local scale knowledge base, which should improve climate adaptation planning and resilience effort and environmental management decisions (Conde et al., 2015). Where such knowledge gaps persist, the implementation of climate change adaptation measures could proceed on the basis of a set of general principals of best practice (Sheaves et al., 2016; Thorne et al., 2017).

Benefits of effective government adaptation response includes the promotion of sustainable use, development and protection of coastal ecosystems (Rosendo et al., 2018) and the protection of biodiversity through setting appropriate conservation priorities (Gormley et al., 2015). Improved governance includes consideration of social processes in risk management (Gerkensmeier and Ratter, 2018; Rosendo et al., 2018) and improved systematic conservation planning (Johnson et al., 2018). At a local level, this translates into sustained service delivery (Aylett, 2015), improved rationality and effective policy making (Serrao-Neumann et al., 2013; Rosendo et al., 2018).

Improving the implementation and coordination of policies and improving integrated coastal management are both considered important climate change adaptation governance responses ( ''robust evidence, high agreement'' ), as are developing partnerships and building capacity ( ''medium evidence, high agreement'' ) and adopting or mainstreaming sustainability policies ( ''limited evidence, medium agreement'' ). Benefits include improved ecosystem resilience, better planning processes, implementation and policies (all ''limited evidence, medium agreement'' ).

<div id="section-5-5-2-3ocean-based-climate-change-adaptation-frameworks"></div>

<span id="ocean-based-climate-change-adaptation-frameworks"></span>
==== 5.5.2.3 Ocean-based Climate Change Adaptation Frameworks ====

<div id="section-5-5-2-3ocean-based-climate-change-adaptation-frameworks-block-1"></div>

Adaptation action in pursuit of a climate resilient development pathway is likely to have a deeper transformative outcome than stepwise or ad hoc responses (Cross-Chapter Box 2 in Chapter 1). Recent literature highlighting the effectiveness of components of adaptation planning includes quantitative assessments of vulnerability in ecosystems (Kuhfuss et al., 2016), species (Cheung et al., 2015; Cushing et al., 2018), and communities (Islam et al., 2013; Himes-Cornell and Kasperski, 2015b), and integrated assessments of all of the above (Peirson et al., 2015; Kaplan-Hallam et al., 2017; McNeeley et al., 2017; Ramm et al., 2017; Mavromatidi et al., 2018). Seasonal and decadal forecasting tools have improved rapidly since AR5, especially in supporting management of living marine resources (Payne et al., 2017) and modelling to support decision making processes (Čerkasova et al., 2016; Chapman and Darby, 2016; Jiang et al., 2016; Justic et al., 2016; Joyce et al., 2017; Mitchell et al., 2017). Decision making processes are supported by economic evaluations (Bujosa et al., 2015; Jones et al., 2015), evaluations of ecosystem services (MacDonald et al., 2017; Micallef et al., 2018), participatory processes (Byrne et al., 2015) and social learning outcomes, the development of adaptation pathways, frameworks and decision making (Buurman and Babovic, 2016; Dittrich et al., 2016; Michailidou et al., 2016a; Osorio-Cano et al., 2017; Cumiskey et al., 2018), and indicators to support evaluation of adaptation actions (Carapuço et al., 2016; Nguyen et al., 2016) through monitoring frameworks (Huxham et al., 2015). Climate change adaptation responses are more effective when developed within institutional frameworks that include effective planning and cross-sector integration.

Evidence-based decision making for climate adaptation is strongly supported in the literature (Endo et al., 2017; Thorne et al., 2017) through better understanding of coastal ecosystems and human adaptation responses (Dutra et al., 2015; Cvitanovic et al., 2016), as well as consideration of non-climate change related factors. Relevant research includes the topics of: multiple-stakeholder participatory planning (Archer et al., 2014; Abedin and Shaw, 2015); trans-boundary ocean management (Gormley et al., 2015; Williams et al., 2016); ecosystem-based adaptation (Hobday et al., 2015; Dalyander et al., 2016; McNeeley et al., 2017; Osorio-Cano et al., 2017); and community-based adaptation with socioeconomic outcomes (Merkens et al., 2016). Research on applying ‘big data’ and high end computational capabilities could also help develop a comprehensive understanding of climate and non-climate variables in planning for coastal adaptation (Rumson et al., 2017). New knowledge from these research areas could substantially improve planning, implementation and monitoring of climate adaptation responses for marine systems, if research processes are participatory and inclusive ( ''medium confidence'' ).

Despite such interest, evaluations of the planning, implementation and monitoring of adaptation actions remain scarce (Miller et al., 2017). In a global analysis of 401 local governments, only 15% reported on adaptation actions (mostly large cities in high income countries), and 18% reported on planning towards adaptation policy (Araos et al., 2016). Thus, integrated adaptation planning with non-climate change related impacts remains an under-achieved ambition, especially in developing countries (Finkbeiner et al., 2018). Challenges reported for adaptation planning include uncoordinated, top-down approaches, a lack of political will, insufficient resources (Elias and Omojola, 2015; Porter et al., 2015), and access to information (Thorne et al., 2017).

Characteristics of successful adaptation frameworks include: a robust but flexible approach, accounting for deep uncertainty through well-coordinated participatory processes (Dutra et al., 2015; Jiao et al., 2015; Buurman and Babovic, 2016; Dittrich et al., 2016); well-developed monitoring systems (Barrett et al., 2015; Bell et al., 2018b); and taking a whole systems approach (Sheaves et al., 2016), with the identification of co-benefits for human development and the environment (Wise et al., 2016). The coastal adaptation framework literature is dominated by Australian, North American and European cities, with fewer studies from African and Caribbean sites, least developed countries and SIDS (Kuruppu and Willie, 2015; Torresan et al., 2016).

In contrast with the many examples of proposed frameworks for climate resilient coastal adaptation, few studies have assessed their success, possibly due to the time-lag between implementation, monitoring, evaluation and reporting. Nevertheless, there is substantial support for ‘no regrets’ approaches addressing both proximate and systematic underlying drivers of vulnerability (Sánchez-Arcilla et al., 2016; Pentz and Klenk, 2017; Zandvoort et al., 2017) with leadership, adaptive management, capacity and the monitoring and evaluation of actions considered useful in governance responses (Dutra et al., 2015; Doherty et al., 2016). More extensive learning processes could help build decision makers’ capacity to tackle systemic drivers, guide pursuance climate change appropriate policies (Barange et al. 2018) and to scrutinise potentially maladaptive infrastructural investments (Wise et al., 2016). More effective coordination across a range of stakeholders, within and between organisations, especially in developing countries, would strengthen the global coastal adaptation response ( ''medium confidence'' ).

<div id="section-5-5-2-4the-role-of-education-and-local-knowledge-in-adapting-to-climate-change"></div>

<span id="the-role-of-education-and-local-knowledge-in-adapting-to-climate-change."></span>
==== 5.5.2.4 The Role of Education and Local Knowledge in Adapting to Climate Change. ====

<div id="section-5-5-2-4the-role-of-education-and-local-knowledge-in-adapting-to-climate-change-block-1"></div>

Education can help improve understanding of issues related to climate change and increase adaptive capacity (Fauville et al., 2011; Marshall et al., 2013; von Heland et al., 2014; Pescaroli and Magni, 2015; Tapsuwan and Rongrongmuang, 2015; Wynveen and Sutton, 2015). Participatory processes can facilitate the development of networks between coastal communities and environmental managers for the purposes of developing and implementing adaptation strategies (Wynveen and Sutton, 2015). Education, combined with other forms of institutional support empowers fisheries and aquaculture communities (Table 5.8) to make informed adaptation decisions and take action ( ''medium evidence, medium agreement)'' .

Local knowledge and Indigenous knowledge systems can complement scientific knowledge by, for example, improving community ability to understand their local environment (Andrachuk and Armitage, 2015), forecast extreme events (Audefroy and Sánchez, 2017) and help to increase community resilience (Leon et al., 2015; Sakakibara, 2017; Cinner et al., 2018; Panikkar et al., 2018). Committing resources could strengthen local level adaptation planning (Alam et al., 2016; Novak Colwell et al., 2017) through the inclusion of cultural practices (Audefroy and Sánchez, 2017; Fatorić and Seekamp, 2017) and Indigenous knowledge systems (Kuruppu and Willie, 2015; von Storch et al., 2015). Local knowledge can, however, act as a barrier to adaptation where there is a strong dependency upon such knowledge for immediate survival, to the detriment of long-term adaptation planning (Marshall et al., 2013; Metcalf et al., 2015). There is evidence, however, to suggest that vulnerability in fisheries communities and coastal tourism operators with high levels of local knowledge is reduced where they have a correspondingly high level of adaptive capacity (Marshall et al., 2013). Resource users with high levels of local knowledge may also be able to identify signals of change within their environment, and recognise the need to adapt. In these instances, fishers with higher local knowledge are expected to demonstrate a higher adaptive capacity than fishers with lower local knowledge, and can be expected to progress towards developing new strategies to combat the impacts of climate change (Kittinger et al., 2012). In these instances, local knowledge acts to promote adaptation ( ''medium confidence'' ).

Localised, individual-scale behaviors can aggregate rapidly and contribute to the global adaptation response. This can be supported by clear messaging that clarifies the role of individuals, households and local businesses in addressing climate change. Coastal communities can improve the co-production of climate change knowledge ( ''medium evidence, good agreement'' ) through the integration of knowledge systems (Table 5.8). In fisheries and aquaculture, better-informed decision making tools ( ''medium evidence, medium agreement'' ) are supported by improved participatory processes ( ''high confidence'' ), integrating knowledge systems ( ''medium evidence, good agreement'' ) and improving decision support frameworks ( ''medium evidence, medium agreement'' ).

<div id="section-5-5-2-5costs-and-limits-for-coastal-climate-change-adaptation"></div>

<span id="costs-and-limits-for-coastal-climate-change-adaptation"></span>
==== 5.5.2.5 Costs and Limits for Coastal Climate Change Adaptation ====

<div id="section-5-5-2-5costs-and-limits-for-coastal-climate-change-adaptation-block-1"></div>

Challenges persist in conducting economic assessments for built infrastructure adaptation due to complicated uncertainties such as the accuracy of climate projections and limited information regarding paths for future economic growth and adaptation technologies. Annual investment and maintenance costs of protecting coasts were projected to be 12–71 billion USD (Hinkel et al., 2014), which was considered significantly less than damage costs in the absence of such action. In an analysis of twelve Pacific island countries, 57% of assessed built infrastructure was located within 500 m of coastlines, requiring a replacement value of 21.9 billion USD. Substantial coastal adaptation costs (and international financing) are likely to be required in these countries ( ''medium confidence'' ).

In West African fisheries, loss of coastal ecosystems and productivity are estimated to require 5–10% of countries’ GDP in adaptation costs (Zougmoré et al., 2016). Similarly, for Pacific Islands and Coastal Territories, fisheries adaptation will require significant investment from local governments and the private sector (Rosegrant et al., 2016), with adaptation costs considered beyond the means of most of these countries (Campbell, 2017). In SIDS, tourism could provide the funding for climate change adaptation, but concerns with creating investment barriers, assumptions around cost-effectiveness and consumer driven demand remain barriers (Hess and Kelman, 2017). MPAs with multiple co-benefits, are considered a cost-effective strategy (Byrne et al., 2015). In 2004, the annual cost of managing 20–30% of global seas as MPAs was estimated at between 5–19 billion USD, with the creation of approximately one million jobs (Balmford et al., 2004).

Estimating adaptation costs is challenging because of wide ranging regional responses and uncertainty (Dittrich et al., 2016). Despite these challenges, the protection from flooding and frequent storms that coral reefs provide has been quantified by (Beck et al., 2018), who estimated that without reefs, damage from flooding and costs from frequent storms would double and triple respectively, while countries from Southeast Asia, East Asia and Central America could each save in excess of 400 million USD through good reef management. Although quantifying global adaptation costs remains challenging because of a wide range of regional responses and contexts, it is likely that managing ecosystems will contribute towards reducing costs associated with climate change associated coastal storms ( ''medium confidence'' ). Further research evaluating natural infrastructure is required (Roberts et al., 2017) to better understand costs and benefits of EBA.

There is a broad range of reported barriers and limits to climate change adaptation for both ecosystems and human systems. Coastal ecosystem-based adaptation can be physically constrained by space requirements and coastal squeeze (Sutton-Grier et al., 2015; Robins et al., 2016; Sánchez-Arcilla et al., 2016; Ahmed et al., 2017; Peña-Alonso et al., 2017; Salgado and Martinez, 2017; Triyanti et al., 2017; Schuerch et al., 2018), while the pace of climate change may exceed the adaptive capacity of ecosystems, for example, SLR may outpace the vertical reef accretion rate (Beetham et al., 2017; Elliff and Silva, 2017; Joyce et al., 2017). One technical limit for coral reef adaptation is that tools have not yet been developed for large-scale implementation (van Oppen et al., 2017a). Ecosystems may also have physiological and ecological constraints which are exceeded by climate change impacts (Miller et al., 2017; Wigand et al., 2017), and the recovery periods of natural systems (Gracia et al., 2018) and for ecological succession (Salgado and Martinez, 2017) may be outpaced by climate change impacts. The performance of ecosystems in EBA projects may be inhibited by the poor condition of the ecosystem (Nehren et al., 2017), highlighting the importance of effective implementation (Salgado and Martinez, 2017).<br />
<br />
Social and cultural norms with conflicting and competing values (Miller et al., 2017), public lack of knowledge on climate change and distrust of information sources (Wynveen and Sutton, 2015), as well as populations increasingly distanced from, and unconcerned about nature (Romañach et al., 2018), may constrain ecosystem-based adaptation response. Examples of governance adaptation constraints include: inadequate policy, governance and institutional structures (Sánchez-Arcilla et al., 2016; Miller et al., 2017; Wigand et al., 2017), limited capacity (Sutton-Grier et al., 2015; Thorne et al., 2017), ineffective implementation (Nguyen et al., 2017; Comte and Pendleton, 2018), and poor enforcement (Nguyen et al., 2017). Governance constraints are compounded by lack of finances (Miller et al., 2017), financial costs of design and implementation (Gallagher et al., 2015) and the high cost of coastal land (Gracia et al., 2018), although ecosystem-based adaptation is considered cheaper than human-made structures (Nehren et al., 2017; Salgado and Martinez, 2017; Vikolainen et al., 2017; Gracia et al., 2018).

Knowledge limitations can include a lack of data (Sutton-Grier et al., 2015; Wigand et al., 2017; Romañach et al., 2018), for example, when an absence of baseline data may undermine coastline management (Perkins et al., 2015). Scale-relevant information may be required for local decision making (Robins et al., 2016; Thorne et al., 2017) and to comply with localised design requirements (Vikolainen et al., 2017). Other knowledge barriers include inherent uncertainties in models (Schaeffer-Novelli et al., 2016) and complexity of coastal systems (Wigand et al., 2017). A more nuanced knowledge barrier is the disconnect between scientific, community and decision making processes (Romañach et al., 2018).

Substantial knowledge gaps are reported for ecosystem-based adaptation, including restoration of coral reef systems as an adaptation tool (Comte and Pendleton, 2018), managing mangrove and human response to climate change (Ward et al., 2016), advancing coastal EBA science by quantifying ecosystem services (Hernández-González et al.), and evaluating natural infrastructure (Roberts et al., 2017). Few syntheses of the context-specific application and cost-effectiveness of EBA approaches are to be found in the literature (Narayan et al., 2016).<br />

Human systems have similar limitations. Improved understanding of limitations in built infrastructure, beach nourishment and nature-based adaptation responses, especially with respect to cost effectiveness and resilience, would substantially aid shoreline stabilisation attempts (Mackey and Ware, 2018). For artisanal fisheries, a range of physical and socioinstitutional limits and barriers to adaptation have been reported, including increasing occurrence and severity of storms limiting fishing time, technologically poor boats and fishing equipment and lack of access to credit and markets, among others (Islam et al., 2013). Conflicting interests and values of stakeholders (Evans et al., 2016), the path-dependent nature of organisations and resistance to change (Evans et al., 2016) and inadequate collaboration and public awareness (Oulahen et al., 2018) have been reported as socioinstitutional barriers. A knowledge gap persists in understanding how such limits and barriers interact to suppress adaptation response.

In some communities, climate change may not be prioritised in the face of chronic, daily challenges to secure livelihoods (Esteban et al., 2017; Fischer, 2018) or risk severity may be underestimated due to a high frequency of exposure in the recent past (Esteban et al., 2017). In a world with competing risks and urgent priorities, some local inhabitants appear to be unable to avoid, or are willing to carry, the risk associated with a climate impact in order to meet other, more pressing needs. This example reflects the reality of many poor, informal settlement dwellers in coastal areas around the world ( ''medium confidence'' ). Other human system barriers to effective adaptation action include insufficient climate change knowledge, inappropriate coping strategies, high dependency upon natural resources, level of exposure to hazards and weak community networks (Islam et al., 2013; Nanlohy et al., 2015; Lohmann, 2016; Koya et al., 2017; Senapati and Gupta, 2017; Cumiskey et al., 2018).

In summary, it is concluded that the broad range of reported barriers and limits to climate change adaptation for ecosystem and human system adaptation responses ( ''high confidence'' ). Limitations include the space that ecosystems require, non-climatic drivers and human impacts that need to be addressed as part of the adaptation response, the lowering of adaptive capacity of ecosystems because of climate change, and slower ecosystem recovery rates relative to the recurrence of climate impacts, availability of technology, knowledge and financial support and existing governance structures ( ''medium confidence'' ). (5.5.2.5)

<div id="section-5-5-2-6summary"></div>

<span id="summary"></span>
==== 5.5.2.6 Summary ====

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There has been a substantial amount of literature focused on coastal and oceanic adaptation since AR5. Socio-institutional adaptation responses are the more numerous of the three types of adaptation responses assessed in this chapter. There is broad agreement that hard engineering responses are optimally supported by ecosystem-based adaptation approaches, and both approaches should be augmented by socioinstitutional approaches for adaptation ( ''high confidence'' ) (Nicholls et al., 2015; Peirson et al., 2015; Sánchez-Arcilla et al., 2016; van der Nat et al., 2016; Francesch-Huidobro et al., 2017; Khamis et al., 2017). In planning adaptation responses, awareness-raising and stakeholder engagement processes are important for buy-in and ownership of responses ( ''robust evidence, high agreement'' ) as is institutional capacity within local government organisations, whose importance in coastal adaptation initiatives has been emphasised in the recent literature ( ''robust evidence, high agreement'' ). With all three types of adaptation, basic good governance and effective implementation of service delivery processes are prerequisites for successful adaptation planning and response.

<span id="governance-across-all-scales"></span>
=== 5.5.3 Governance Across All Scales ===

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There are many global, regional, national and local governance structures with interests in climate-driven ocean warming, acidification, deoxygenation and SLR, and their impacts on marine ecosystems and dependent communities (Galland et al., 2012 <sup>[[#fn:r2428|2428]]</sup> ; Stephens, 2015 <sup>[[#fn:r2429|2429]]</sup> ; Fennel and VanderZwaag, 2016 <sup>[[#fn:r2430|2430]]</sup> ; Diamond, 2018 <sup>[[#fn:r2431|2431]]</sup> ). The legal, policy and institutional response is therefore shared by many institutions developed for a number of distinct but inter-related fields, including governance regimes for ocean systems, climate change, marine environment, fisheries and the environment generally. A changing ocean poses several scale-related challenges for these governance institutions and processes, arising from:

* The global and transboundary scales of the major changes to ocean properties (temperature, circulation, oxygen loss, acidification, etc.), with variability in their local expression;
* The regional scales of changes in ecosystem services following from the changes in ocean properties (including services provided to humans living far from the coasts);
* The global scales of land-based drivers of those changes (both greenhouse gas emissions and changes in ecosystems services), which often motivate policy responses (primarily at the national level) and behavioural responses (primarily at the community level);
* The scale dependent need for coordinated responses by the different governance structures, to ensure their overall effectiveness (see also Chapter 1)

For all of these challenges, the scales of the climate-related issues may be poorly matched to the scales of most governance institutions and processes, making effective responses or proactive initiatives difficult. Sections 5.2 to 5.4 provide evidence, through case histories and thematic overviews, that illustrates these four types of challenges. In some cases, more than one type of challenge is illustrated in a single example, such as when a change in an amount or availability of an ecosystem service is discussed in the context of factors influencing the vulnerability of socio-ecological systems to climate change (Sections 5.2., 5.3 and 5.4).

Existing ocean governance structures for the ocean already face multi-dimensional challenges because of climate change, and this trend of increasing complexity will continue (Galaz et al., 2012 <sup>[[#fn:r2432|2432]]</sup> ). Current international governance regimes and structures for fisheries and the ocean environment do not yet adequately address the issues of ocean warming, acidification and deoxygenation (Oral, 2018 <sup>[[#fn:r2433|2433]]</sup> ); Box 5.6). At the time of the initial development and adoption of these legal and governance regimes, minimal attention was given to climate change and the effects of carbon dioxide emissions on the ocean, with associated impacts on the interacting physical, chemical, biological properties of the ecosystems, and the resulting risks and vulnerabilities of dependent communities and economic sectors. In particular, the governance of ocean ABNJ is a major challenge (Levin and Le Bris, 2015 <sup>[[#fn:r2434|2434]]</sup> ); the collaborative structures and mechanisms for environmental assessment in ABNJ need further development (Warner, 2018 <sup>[[#fn:r2435|2435]]</sup> ) ( ''high confidence'' ). Negotiations are currently ongoing regarding a new international agreement for marine biodiversity of ABNJ (UNEP, 2016 <sup>[[#fn:r2436|2436]]</sup> ).

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<span id="section-2"></span>
<!-- START TABLE -->
'''Table 5.9:''' Ocean Governance and Climate Change: Major Issues

<!-- TABLE -->
{| class="wikitable"
|-
| Area of Governance
| Major Legal Instruments
| Major Issues and Actions
|-
| Marine Environment Generally
| UNCLOS, CBD, CITES, WHC, MARPOL and other IMO legal instruments, regional seas conventions and other legal instruments
| UNCLOS imposes obligations on state parties to take action to combat the main sources of ocean pollution. Tools and techniques in UNCLOS may need adjustment in response to the emerging challenges created by ocean climate change (Redgwell, 2012). However, success of the umbrella regulatory framework of UNCLOS depends heavily on the further development, modification and implementation of detailed regulations by relevant international, regional and national institutions (Karim, 2015).
The London Protocol to the London Convention was amended in 2006 to address the issue of carbon dioxide storage processes for sequestration. Two subsequent amendments concern sharing transboundary sub-seabed geological formations for sequestration projects, and ocean fertilisation and other marine geoengineering. One of these new amendments prohibits ocean fertilisation except for research purposes (Dixon et al., 2014).

The issue of ocean acidification has been considered within the framework of the OSPAR Convention, the CCAMLR Convention (Herr et al., 2014), and the CBD (CBD,2014) ; this issue is discussed further in Box 5.6.

The CBD has also considered regulatory issues relating to ocean fertilisation and other (marine) geoengineering (Williamson and Bodle, 2016). In 2018, the CBD adopted ''Voluntary Guidelines for the Design and Effective Implementation of Ecosystem-Based Approaches to Climate Change Adaptation and Disaster Risk Reduction'' . However, even if Parties to the Convention choose to adopt the voluntary guidelines, there is no mechanism to implement them beyond their exclusive economic zones in the water column and their extended continental shelves (if recognised) in the seabed

Most of the 29 world heritage listed coral reefs are facing severe heat stress (Heron, 2017) and the WHC may play a role for coral reef protection.

|-
| Climate Change
| UNFCCC, Paris Agreement, MARPOL Convention and other legal instruments
| Existing international legal instruments do not adequately address climate change challenges for the open ocean and coastal seas (Galland et al., 2012; Redgwell, 2012; Herr et al., 2014; Magnan et al., 2016; Gallo et al., 2017; Heron, 2017). Nevertheless, ocean and coastal areas will benefit from the overall UNFCCC goal for preventing dangerous interference with the climate system. A study of the 161 national pledges for climate change mitigation and adaptation (NDCs) identified ‘gaps between scientific [understanding] and government attention, including on ocean deoxygenation, which is barely mentioned’ (Gallo et al., 2017).
In 2011, the MARPOL convention was amended to include technical and operational measures for the reduction of greenhouse gas emissions from ships. However, the effectiveness of these provisions depends on the national implementation by flag, port and coastal states, with no international enforcement authority (Karim, 2015).

|-
| Fisheries
| UNCLOS, UN Fish Stocks Agreement, FAO Compliance Agreement,
FAO PSMA, Regional Fisheries Agreements and other legal instruments

| The impact of climate change on marine fisheries is expected to be very significant (Sections 5.3, 5.4) (Barange et al. 2018; FAO, 2019), with adverse impacts on food security, livelihood and national development in many coastal countries; least developed countries seem particularly vulnerable (Blasiak et al., 2017). Regional fisheries management systems need to address these emerging challenges (Brooks et al., 2013). The ecological and socioecological criteria and standards for performance can be set at regional levels where Regional Fisheries Management Organizations have been established, but their effectiveness is variable depending on the characteristics of regulatory instruments and other factors (Ojea et al., 2017). The current international regulatory framework for fisheries management has a responsiveness gap, since it does not fully incorporate issues related to the fluctuating and changing distribution of fisheries (Pentz and Klenk, 2017; Pinsky et al., 2018).
However, some regional fisheries management organisations (RFMOs) have initiated processes to improve the equity of sharing fishery resources affected by climate change (Aqorau et al., 2018). A climate-informed ecosystem-based fisheries governance approach has been suggested for enhancing climate change resilience of marine fisheries in the developing world (Heenan et al., 2015), but robust and effective management, policy, legislation and planning based on flexibility and scientific understanding will be required for coastal fisheries (Gourlie et al., 2017). The existing failing condition of many stocks, coupled with maladaptive responses to climate change, may create serious challenges for the sustainability of global fisheries; improved fisheries governance can offset some of these challenges (Gaines et al., 2018).

The fisheries agreements and the provisions in UNCLOS have helped RFMOs to increase the sustainability of fisheries on stocks in or migrating through international waters, and equity of access to them. Because the distribution of many stocks changes with changes in physical oceanic conditions (particularly temperature and current regimes), many of the measures and access arrangements negotiated and adopted by the RFMOs have reduced effectiveness in a changing climate. New arrangements have been difficult to negotiate, in part because of concerns that the distributions and productivities will continue to change as climate change continues to drive changes on ocean conditions (Blasiak et al., 2017; Ojea et al., 2017; Pentz and Klenk, 2017; Aqorau et al., 2018; Pinsky et al., 2018).

|}
<!-- END TABLE -->

<div id="section-5-5-3governance-across-all-scales-block-3"></div>

Acronyms and organisations: CBD, Convention on Biological Diversity; CCAMLR, Convention on the Conservation of Antarctic Marine Living Resources; CITES, Convention on International Trade in Endangered Species of Wild Fauna and Flora; IMO: International Maritime Organization; London Convention: Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter; London Protocol: 1996 Protocol to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter; MARPOL Convention: International Convention for the Prevention of Pollution from Ships; NDCs: Nationally Determined Contributions; OSPAR Convention: Convention for the Protection of the Marine Environment of the North-East Atlantic; UN Fish Stocks Agreement: The Agreement for the Implementation of the Provisions of the United Nations Convention on the Law of the Sea of 10 December 1982 relating to the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks; UNCLOS: United Nations Convention on the Law of the Sea; UNFCCC: United Nations Framework Convention on Climate Change; WHC, World Heritage Convention: Convention Concerning the Protection of the World Cultural and Natural Heritage; FAO Compliance Agreement: The Agreement to Promote Compliance with International Conservation and Management Measures by Fishing Vessels on the High Seas; FAO PSMA: The Agreement on Port State Measures

The following changes in governance may improve the ability of governance institutions and processes to address the challenges identified above:

* Cooperation on regional and global scales through various types of agreements of varying degrees of formality for States and other participants in governance
* Increasing the voice and role in decision making for non-governmental participants such as Indigenous peoples, social and labour organisations
* Increasing the horizontal integration of decision making across industry and societal sectors, under processes such as ‘integrated management’ and ‘marine spatial planning’
* Increasing resource mobilisation at the community scale to enable communities to experiment and innovate to address the challenges, and then to share their experiences with other communities and build cooperative approaches to promote strategies with successful outcomes

These governance innovation strategies have the potential to increase the ability of the governance institutions and processes to successfully respond to all four types of scale-related challenges listed earlier. However, any of them also have the potential to fail to address their intended concerns effectively if implemented inappropriately, or to create new challenges as the initial priorities are addressed. In some countries, lack of capacity of the existing governance institutions, lack of access to basic facilities, insufficient income diversification and illiteracy are major hindrance for ocean governance in a changing climate (Bennett et al., 2014 <sup>[[#fn:r2437|2437]]</sup> ; Salik et al., 2015 <sup>[[#fn:r2438|2438]]</sup> ; Weng et al., 2015 <sup>[[#fn:r2439|2439]]</sup> ; Karim and Uddin, 2019 <sup>[[#fn:r2440|2440]]</sup> ; Sarkodie and Strezov, 2019 <sup>[[#fn:r2441|2441]]</sup> ) ( ''high confidence'' )

Additional considerations identified by recent studies of ocean related mitigation and adaptation include the need for: early warning and precautionary management; multi-level and multi-sectoral governance responses; holistic, integrated and flexible management systems; integration of scientific and local knowledge as well as natural, social and economic investigation; identification and incorporation of a set of social indicators and checklists; adaptive governance; and incorporation of climate change effects in marine spatial planning (Hiwasaki et al., 2014 <sup>[[#fn:r2470|2470]]</sup> ; Kettle et al., 2014 <sup>[[#fn:r2471|2471]]</sup> ; Hernández-Delgado, 2015 <sup>[[#fn:r2472|2472]]</sup> ; Himes-Cornell and Kasperski, 2015a <sup>[[#fn:r2473|2473]]</sup> ; Pittman et al., 2015 <sup>[[#fn:r2474|2474]]</sup> ; Colburn et al., 2016 <sup>[[#fn:r2475|2475]]</sup> ; Creighton et al., 2016 <sup>[[#fn:r2476|2476]]</sup> ; Hobday et al., 2016a <sup>[[#fn:r2477|2477]]</sup> ; Audefroy and Sánchez, 2017 <sup>[[#fn:r2478|2478]]</sup> ; Gissi et al., 2019 <sup>[[#fn:r2479|2479]]</sup> ; Tuda et al., 2019 <sup>[[#fn:r2480|2480]]</sup> ). Diverse adaptations of governance are being tried, and some are producing promising results (Sections 5.2, 5.3 and 5.4). However, rigorous further evaluation is needed regarding the effectiveness of these adaptations in achieving their goals in addressing specific governance challenges. Robust conclusions on the effectiveness of specific types of governance adaptations in various socioecological contexts would require a targeted assessment of ocean (and terrestrial) governance in a changing climate, possible as a key part of AR6.

<div id="section-5-5-3governance-across-all-scales-block-4" class="box"></div>

<span id="box-5.6-policy-responses-to-ocean-acidification-is-there-an-international-governance-gap"></span>