Editing IPCC:AR6/WGII/Chapter-15 (section)

=== 15.3.4 Observed Impacts and Projected Risks on Human Systems ===

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==== 15.3.4.1 Island Settlements and Infrastructure ====

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As a result of slow-onset ocean and climate changes and changes in extreme events, settlements and infrastructure of small islands are at growing risk due to climate change in the absence of adaptation measures ( ''high confidence'' ). Ocean acidification and deoxygenation, increased ocean temperatures and relative SLR are impacting marine, coastal and terrestrial biodiversity and ecosystem services, making settlements more exposed and vulnerable to climate-related hazards. Changes in rainfall patterns such as heavy precipitation result in annual flood events that damage major assets and result in a loss of human life. Examples of settlements where this has occurred are Port of Spain ( [[#Mycoo--2014b|Mycoo, 2014b]] ; 2018a), Haiti ( [[#Weissenberger--2018|Weissenberger, 2018]] ), Viti Levu ( [[#Brown--2017|Brown et al., 2017]] ; [[#Singh-Peterson--2018|Singh-Peterson and Iranacolaivalu, 2018]] ), urban areas of Fiji and Kiribati ( [[#McAneney--2017|McAneney et al., 2017]] ; [[#Cauchi--2021|Cauchi et al., 2021]] ), Male’, Maldives ( [[#Wadey--2017|Wadey et al., 2017]] ), and Mahé, in the Seychelles ( [[#Etongo--2019|Etongo, 2019]] ).

The main settlements of small islands are located along the coast and with decades of high-density coastal urban development, their population, buildings and infrastructure are currently exposed to multiple climate change-related hazards ( [[#Kumar--2015|Kumar and Taylor, 2015]] ; [[#Mycoo--2017|Mycoo, 2017]] ) and face key risks ( ''high confidence'' ) (KR5 in Figure 15.5). In many small islands, population is concentrated in the low-elevation coastal zone (LECZ), which is defined as coastal areas below 10-m elevation. Approximately 22 million in the Caribbean live below 6-m elevation ( [[#Cashman--2017|Cashman and Nagdee, 2017]] ) and an estimated 90% of Pacific Islanders live within 5 km of the coast, if Papua New Guinea is excluded ( [[#Andrew--2019|Andrew et al., 2019]] ). In the Solomon Islands and Vanuatu, over 60% of the population lives within 1 km of the coast ( [[#Andrew--2019|Andrew et al., 2019]] ). Most Pacific islands have ≥50% of their infrastructure within 500 m of the coast ( [[#Kumar--2015|Kumar and Taylor, 2015]] ), and in Kiribati, Marshall Islands and Tuvalu, &gt;95% of the infrastructure is located in the LECZ ( [[#Andrew--2019|Andrew et al., 2019]] ) (Figure 15.3). Sustainable development challenges including insufficient land use planning and land use competition contribute to increased vulnerability of human settlements to climate change in small islands ( [[#Kelman--2014|Kelman, 2014]] ; Mycoo, 2021).

Categories 4 and 5 TCs are severely impacting settlements and infrastructure in small islands. TC Maria in 2017 destroyed nearly all of Dominica’s infrastructure and losses per unit of GDP amounted to more than 225% of the annual GDP ( [[#Eckstein--2018|Eckstein et al., 2018]] ). Destruction from TC Winston in 2016 amounted to more than 20% of Fiji’s current GDP ( [[#Cox--2018|Cox et al., 2018]] ). Additionally, living conditions in human settlements are changing due to storm surge which is already penetrating further inland compared with a few decades ago ( [[#IPCC--2018|IPCC, 2018]] , [[IPCC:Wg2:Chapter:Chapter-3#3.4.4|Section 3.4.4.3]] ; [[#Brown--2018|Brown et al., 2018]] ).

A growing percentage of the population in small islands lives in informal settlements which occupy marginal lands leading to increased population exposure and vulnerability to climate-related hazards ( [[#Mycoo--2017|Mycoo and Donovan, 2017]] ). Unplanned settlements have compounded flooding brought on by slow-onset hazards such as coastal and riverine flooding and fast-onset events such as TCs and storm surges ( [[#Butcher-Gollach--2015|Butcher-Gollach, 2015]] ; [[#Chandra--2016|Chandra and Gaganis, 2016]] ; [[#Mycoo--2017|Mycoo, 2017]] ). Unsustainable land use practices and difficulties in enforcing land use zoning and building guidelines in informal settlements make them highly vulnerable to such events ( [[#Butcher-Gollach--2015|Butcher-Gollach, 2015]] ; [[#Mecartney--2017|Mecartney and Connell, 2017]] ; [[#Mycoo--2017|Mycoo, 2017]] ; 2018b; 2021; [[#Trundle--2018|Trundle et al., 2018]] ).

TC intensification in the future is ''likely'' to cause severe damage to human settlements and infrastructure in small islands. Additionally, SLR is expected to cause significant losses and damages ( [[#Martyr-Koller--2021|Martyr-Koller et al., 2021]] ). Based on SLR projections, almost all port and harbour facilities in the Caribbean will suffer inundation in the future ( [[#Cashman--2017|Cashman and Nagdee, 2017]] ). In Jamaica and St. Lucia, SLR and ESLs are projected to be key risks to transport infrastructure at 1.5°C unless further adaptation is undertaken ( [[#Monioudi--2018|Monioudi et al., 2018]] ). Similar findings were reported for Samoa ( [[#Fakhruddin--2015|Fakhruddin et al., 2015]] ). Even islands of higher elevation are expected to be threatened, given the high amount of infrastructure located near the coast, for example, Fiji ( [[#Kumar--2015|Kumar and Taylor, 2015]] ).

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==== 15.3.4.2 Human Health and Well-Being ====

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Small islands face disproportionate health risks associated with changes in temperature and precipitation, climate variability, and extremes (Cross-Chapter Box INTERREG in Chapter 16; KR4 in [[#15.3|Section 15.3.9]] , Figure 15.5). Climate change is projected to increase the current burden of climate-related health risks ( [[#Weatherdon--2016|Weatherdon et al., 2016]] ; [[#Ebi--2018|Ebi et al., 2018]] ; [[#Schnitter--2019|Schnitter et al., 2019]] ). Health risks can arise from exposures to extreme weather and climate events, including heatwaves; changes in ecological systems associated with changing weather patterns that can result, for example, in more disease vectors, or in compromised safety and security of water and food; and exposures related to disruption of health systems, migration, and other factors (see Cross-Chapter Box ILLNESS in Chapter 2; [[#McIver--2016|McIver et al., 2016]] ; [[#Mycoo--2018a|Mycoo, 2018a]] ; [[#WHO--2018|WHO, 2018]] ).

Extreme weather and climate events, particularly TCs, floods, drought, and heatwaves can cause injuries, infectious diseases, and deaths (Box 15.1; [[#Schütte--2018|Schütte et al., 2018]] ). For example, Category 5 TC Winston hit Fiji on 20 February 2016. During the national state of emergency (7 March and 29 May 2016), the World Health Organization portable toolkit for an early warning alert and response system (EWARS in a Box) was deployed within 24 h; it recorded 34,113 cases of the nine syndromes among 326,861 consultations in a population of about 900,000; 48% of cases were influenza-like illnesses, 30% were acute watery diarrhoea, and 13% were suspected cases of dengue. There also were 583 cases of Zika-like illness (1.7% of all cases) and two large outbreaks of viral conjunctivitis (total of 880 cases). During TC Maria in Puerto Rico, there were more deaths per 100,000 among individuals living in municipalities with the lowest socioeconomic development and for men 65 years of age or older ( [[#Santos-Burgoa--2018|Santos-Burgoa et al., 2018]] ); this excess risk persisted for at least 1 year after the event. The first human cases of leptospirosis in the U.S. Virgin Islands occurred in 2017 after TC Irma and Maria. TCs also can affect treatment and care for people with non-communicable diseases, including exacerbation or complications of illness and premature death ( [[#Ryan--2015|Ryan et al., 2015]] ).

Heat-related mortality and risks of occupational heat stress in small island states are projected to increase with higher temperatures ( [[#Hoegh-Guldberg--2018|Hoegh-Guldberg et al., 2018]] ; [[#Mendez-Lazaro--2018|Mendez-Lazaro et al., 2018]] ). Higher temperatures can also affect the productivity of outdoor workers ( [[#Taylor--2021|Taylor et al., 2021]] ). Climate change, urbanisation, and air pollution are risk factors for the rise of allergic diseases in Asia Pacific ( [[#Pawankar--2020|Pawankar et al., 2020]] ).

Tropical and subtropical islands face risks from vector-borne diseases, such as malaria, dengue fever, and the Zika virus. El Niño events can increase the risk of diseases such as Zika virus by increasing biting rates, decreasing mosquito mortality rates and shortening the time required for the virus to replicate within the mosquito ( [[#Caminade--2017|Caminade et al., 2017]] ). By combining disease prediction models with climate indicators that are routinely monitored, alongside evaluation tools, it is possible to generate probabilistic dengue outlooks in the Caribbean and early warning systems ( [[#Oritz--2015|Oritz et al., 2015]] ; [[#Lowe--2018|Lowe et al., 2018]] ). Projections suggest that more individuals will become at risk of dengue fever by the 2030s and beyond because of an increasing abundance of mosquitos and larger geographic range ( [[#Ebi--2018|Ebi et al., 2018]] ). Projected increases in mean temperature could double the dengue burden in New Caledonia by 2100 ( [[#Teurlai--2015|Teurlai et al., 2015]] ). In the Caribbean, Saharan dust transported across the Atlantic can interact with Caribbean seasonal climatic conditions to become respirable and contribute to asthma presentations at the emergency department (See Table 15.5; [[#Akpinar-Elci--2015|Akpinar-Elci et al., 2015]] ).

Ciguatera fish poisoning (CFP) is a foodborne illness caused by toxic dinoflagellate algae that proliferate on degraded coral reefs and that can contaminate reef fish; symptoms can remain for a few weeks to months. CFP occurs in tropical and subtropical regions, primarily in the South Pacific and Caribbean, but wherever reef fish are consumed ( [[#Traylor--2020|Traylor and Singhal, 2020]] ). In the Caribbean Sea, increasing ocean temperatures are expected to stabilise or slightly decrease the incidence of CFP because of shifts in species distribution of dinoflagellates associated with CFP ( [[#Kibler--2015|Kibler et al., 2015]] ). CFP is endemic in the Cook Islands and French Polynesia, where incidence is associated with SST anomalies ( [[#Zheng--2020|Zheng et al., 2020]] ). In the Canary Islands, tropicalisation trends due to climate change are expected to increase CFP occurrence in the future ( [[#Rodriguez--2017|Rodriguez et al., 2017]] ). In addition, in the Caribbean, increased density of ''Sargassum'' algae, possibly due to ocean temperature impacts on ocean currents compounded by agricultural pollution, may lead to increased respiratory illnesses ( [[#Resiere--2018|Resiere et al., 2018]] ; 2019; 2020).

Climate-driven changes in the ability to access locally grown or harvested food, either through environmental degradation or changes in extreme event magnitude and/or frequency, can increase dependence on imported food and increase rates of malnutrition and non-communicable diseases ( [[#Springmann--2016|Springmann et al., 2016]] ; [[#WHO--2018|WHO, 2018]] ; [[#Savage--2019|Savage et al., 2019]] ; [[#Lieber--2020|Lieber et al., 2020]] ). Projections suggest that local food accessibility could be reduced by 3.2% in the low- and middle-income countries of the Western Pacific (including the Philippines, Fiji, Papua New Guinea, Solomon Islands, and other Pacific islands) by 2050, with approximately 300,000 associated deaths possible ( [[#Springmann--2016|Springmann et al., 2016]] ). A climate change-related 20% decline in coral reef fish production in some Pacific Island countries by 2050 could exacerbate the population growth-driven gap between volume of fish needed for nutritional security and fish available through sustained harvest ( [[#Bell--2013|Bell et al., 2013]] ; [[#Cauchi--2019|Cauchi et al., 2019]] ; [[#Savage--2019|Savage et al., 2019]] )).

Heavy reliance on aquifers and rainwater harvesting in small islands, particularly atolls, coupled with overcrowding, population growth and contamination increase the risk of waterborne disease ( [[#McIver--2014|McIver et al., 2014]] ; 2016; [[#Strauch--2014|Strauch et al., 2014]] ). For example, seasonal rainfall in Kiribati is associated with waterborne disease (such as diarrhoea, cholera, and typhoid fever). Future projections indicate increases in the number of days of heavy rainfall by 2050, suggesting future increases in risk in heavily populated areas ( [[#McIver--2014|McIver et al., 2014]] ). Damage to water and sanitation services can cause infectious disease outbreaks, such as the cholera outbreak that occurred in Haiti following TC Matthew ( [[#Raila--2017|Raila and Anderson, 2017]] ; [[#Hulland--2019|Hulland et al., 2019]] ).

Evidence is emerging of the mental health impacts of climate change (limited evidence). Tuvaluans are experiencing distress because of the local environmental impacts caused or exacerbated by climate change, and by hearing about the potential future consequences of climate change ( [[#Gibson--2020|Gibson et al., 2020]] ).

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==== 15.3.4.3 Water Security ====

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Climate change impacts on freshwater systems frequently exacerbate existing pressure, especially in locations already experiencing water scarcity ( [[#15.3.3.2|Section 15.3.3.2]] and Cross-Chapter Box INTERREG in Chapter 16; [[#Schewe--2014|Schewe et al., 2014]] ; [[#Holding--2016|Holding et al., 2016]] ; [[#Karnauskas--2016|Karnauskas et al., 2016]] ), making water security a key risk (KR4 in Figure 15.5) in small islands. Small islands are usually environments where demand for resources related to socioeconomic factors such as population growth, urbanisation and tourism already place increasing pressure on limited freshwater resources. In many small islands, water demand already exceeds supply. For example, in the Caribbean, Barbados is utilising close to 100% of its available water resources and St. Lucia has a water supply deficit of approximately 35% ( [[#Cashman--2014|Cashman, 2014]] ). On many Mediterranean islands, water demand regularly outstrips supply as a result of low average precipitation coupled with increasing water demand from economic activities such as irrigated agriculture and tourism ( [[#Hof--2014|Hof et al., 2014]] ; [[#Papadimitriou--2019|Papadimitriou et al., 2019]] ).

Population growth plays a major role in projected future water stress ( [[#Schewe--2014|Schewe et al., 2014]] ). Combining projected aridity change (fractional change compared to historical climatology) with population projections derived from SSP2 shows that the SIDS with high projected population growth rates are expected to experience the most severe freshwater stress by 2030 under a 2°C warming threshold scenario ( [[#Karnauskas--2018|Karnauskas et al., 2018]] ). For several SIDS (e.g., Belize and Jamaica), increasing aridity change is a prominent exacerbating factor, but for others (e.g., the Solomon Islands and Comoros) population growth is the main factor. An increase in temperature of 1°C (from 1.7°C to 2.7°C) could result in a 60% increase in the number of people projected to experience severe water resources stress in the period 2043–2071 ( [[#Schewe--2014|Schewe et al., 2014]] ; [[#Karnauskas--2018|Karnauskas et al., 2018]] ). Research on Jamaica concluded that the ability of rainwater harvesting to meet potable water needs between the 2030s and 2050s will be reduced based on predicted shorter intense showers and frequent dry spells ( [[#Aladenola--2016|Aladenola et al., 2016]] ).

The Caribbean and Pacific regions have historically been affected by severe droughts ( [[#Peters--2015|Peters, 2015]] ; [[#FAO--2016|FAO, 2016]] ; [[#Barkey--2017|Barkey and Bailey, 2017]] ; [[#Paeniu--2017|Paeniu et al., 2017]] ; [[#Trotman--2017|Trotman et al., 2017]] ; [[#Anshuka--2018|Anshuka et al., 2018]] ) with significant physical impacts and negative socioeconomic outcomes. Water quality is affected by drought as well as water availability. The El Niño related 2015–1016 drought in Vanuatu led to reliance on small amounts of contaminated water left at the bottom of household tanks ( [[#Iese--2021a|Iese et al., 2021a]] ). The highest land disturbance percentages have coincided with major droughts in Cuba ( [[#de%20Beurs--2019|de Beurs et al., 2019]] ). Drought has been shown to have an impact on rainwater harvesting in the Pacific ( [[#Quigley--2016|Quigley et al., 2016]] ) and Caribbean ( [[#Aladenola--2016|Aladenola et al., 2016]] ), especially in rural areas where connections to centralised public water supply have been difficult. Increasing trends in drought are apparent in the Caribbean ( [[#Herrera--2017|Herrera and Ault, 2017]] ) although trends in the western Pacific are not statistically significant ( [[#McGree--2016|McGree et al., 2016]] ).

Areas where a freshwater lens is thinner are most likely to be impacted by multiple climate stressors, and these areas tend to be in coastal zones where populations are likely to be most concentrated ( [[#Holding--2016|Holding et al., 2016]] ). In Barbados, where groundwater is relied upon for food production, urban use and environmental needs, higher food prices are expected in the future if informed land use management and integrated water resources policies are not implemented to manage groundwater in the short term, even with modest climate change threats ( [[#Gohar--2019|Gohar et al., 2019]] ).

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==== 15.3.4.4 Fisheries and Agriculture ====

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Fisheries provide small islands with opportunities for economic development, revenues, food security and livelihoods ( [[#Bell--2018|Bell et al., 2018]] ). Ten Pacific Island countries and territories derive between 5% and &gt;90% of all government revenue (except grants) from access fees paid by industrial tuna-fishing fleets, mainly from distant-water fishing nations ( [[#Bell--2018|Bell et al., 2018]] ; [[#SPC--2019|SPC, 2019]] ). Under a high greenhouse gas emissions scenario (RCP8.5), the total biomass of three tuna species in the waters of 10 Pacific SIDS could decline by an average of 13% (range = −5–−20%) due to a greater proportion of fish occurring in the high seas ( [[#Bell--2021|Bell et al., 2021]] ), while projected increases have been anticipated for Ascension Island and Saint Helena in the South Atlantic ( [[#Townhill--2021|Townhill et al., 2021]] ). Additionally, seafood plays an important role in achieving food security in many islands. In the Pacific, fish protein is estimated to make up 50–90% of animal protein consumption in rural areas and 40–80% in urban areas ( [[#Bell--2009|Bell et al., 2009]] ; [[#Hanich--2018|Hanich et al., 2018]] ) with similar values reported for some Indian Ocean and Caribbean islands (e.g., Maldives, Antigua and Barbuda). It has been suggested that island nations may need to retain more of their tuna catch rather than to rely solely on coastal fisheries to achieve food security in the future (Cross-Chapter Box MOVING PLATE in Chapter 5; [[#Bell--2015|Bell et al., 2015]] ; [[#Bell--2018|Bell et al., 2018]] ). Furthermore, small island fisheries can be severely impacted by extreme events such as TCs, yet rapidly recovering pelagic fisheries can help to alleviate immediate food insecurity pressures in some circumstances, helping to build resilience ( [[#Pinnegar--2019|Pinnegar et al., 2019]] ).

Observed impacts of climate change on fish and fisheries in small islands include declines in reef-associated species due to coral bleaching or cyclone damage ( [[#Robinson--2019|Robinson et al., 2019]] ; [[#Magel--2020|Magel et al., 2020]] ), oceanic-scale shifts in the distribution of large pelagic fish and hence their fisheries ( [[#Erauskin-Extramiana--2019|Erauskin-Extramiana et al., 2019]] ), changes to the size structure or breeding behaviour of species (e.g., ( [[#Asch--2018|Asch et al., 2018]] ) (Sections 3.3.3.2 and 3.4.3.1)). Many studies of future fishery productivity in a changing climate suggest that yields will fall as a result of ocean productivity reductions, local species extinction and/or migration ( [[#Nurse--2011|Nurse, 2011]] ; [[#Asch--2018|Asch et al., 2018]] ; [[#Robinson--2019|Robinson et al., 2019]] ). Asch et al. (2018) provided future projections for biodiversity and the maximum catch potential of fisheries in Pacific Island countries and territories. These authors concluded that nine of 17 Pacific Island entities (Cook Islands, Federated States of Micronesia, Guam, Kiribati, Marshall Islands, Niue, Papua New Guinea, Solomon Islands, and Tuvalu) could experience ≥50% declines in maximum catch potential by 2100 relative to 1980–2000 under both an RCP2.6 and RCP8.5 scenario ( ''medium confidence'' ). In Wallis and Futuna, maximum catch potential was projected to increase slightly (around 10%) by 2050, later declining by the year 2100. Similar projections have now been provided for all countries worldwide, including Pacific, Caribbean, Atlantic, Mediterranean and Indian Ocean small islands ( [[#Cheung--2018|Cheung et al., 2018]] ). The small islands that show the largest anticipated decrease in the maximum catch potential of fisheries by the end of the century (according to an RCP4.5 and RCP8.5 scenario) include the Federated States of Micronesia, Kiribati, Nauru, Palau, Tokelau, Tuvalu, São Tomé and Príncipe, whereas some other small islands such as Bermuda, Easter Island (Chile), and Pitcairn Islands (UK), might actually witness increases in fish catch potential ( ''medium confidence'' ) ( [[#Cheung--2018|Cheung et al., 2018]] ). [[#Monnereau--2017|Monnereau et al. (2017)]] showed that for the fisheries sector, small island states are generally more vulnerable to climate change impacts compared to continental least-developed countries or coastal states because of their increased reliance on fisheries, the exposure of coastal communities to potential climatic threats and their limited adaptive capacity.

Projected impacts of climate change on agriculture and fisheries pose serious threats to dependent human populations ( [[#Ren--2018|Ren et al., 2018]] ; [[#Hoegh-Guldberg--2019|Hoegh-Guldberg et al., 2019]] ), making the risk caused to livelihoods a key risk in small islands (KR7 in Figure 15.5). On small islands, despite biophysical commonalities (e.g., size and isolation), differences in economic status and level of dependence on agriculture and fisheries produce dynamic climate impacts ( [[#Balzan--2018|Balzan et al., 2018]] ). Climate change is impacting agricultural production in small islands through slow-onset stressors such as rising average temperatures, shifting rainfall patterns, SLR and extreme events like TCs. For example, TC Pam, a Category 5 cyclone, devastated Vanuatu in 2015 and caused losses and damages to the agriculture sector valued at USD 56.5 million (64.1% of GDP) ( [[#Nalau--2017|Nalau et al., 2017]] ), and TC Winston in 2016 resulted in losses and damages in the agriculture sector in Fiji valued at USD 254.7 million ( [[#Iese--2020|Iese et al., 2020]] ). In 2017, total losses and damages associated with hurricane Maria (Category 5) amounted to 224% of Dominica’s 2016 GDP ( [[#Barclay--2019|Barclay et al., 2019]] ). Losses and damages in agriculture often led to people eating imported processed foods affecting their diet and nutrition ( [[#Haynes--2020|Haynes et al., 2020]] ). Small islands communities are also witnessing the indirect effects of the COVID-19 pandemic on agricultural systems ( [[#Hickey--2020|Hickey and Unwin, 2020]] ). However, the limited diversity of agriculture production and reduced household incomes are contributing to low diet diversity (Iese et al., 2021b). [[#Bell--2015|Bell and Taylor (2015)]] assessed the effects of climate change on specific sectors of agriculture in the Pacific islands region and found that, by 2090, staple food crops of taro, sweet potato and rice are expected to suffer from moderate to high impact. Among export crops, coffee is expected to sustain the most significant impact due largely to increased temperatures in the highland areas of Papua New Guinea—a high production area ( [[#Bell--2016|Bell et al., 2016]] ). Livestock is an important protein source in some small islands and is particularly vulnerable to changes in temperature through heat stress ( [[#Bell--2015|Bell and Taylor, 2015]] ; [[#Lallo--2018|Lallo et al., 2018]] ). With the concentration of island people along (often reef-fringed) coasts, there is a comparatively large dependence on nearshore marine foods and coastal agricultural systems ( [[#Ticktin--2018|Ticktin et al., 2018]] ).

In the Caribbean, additional warming by 0.2°–1.0°C could lead to a predominantly drier region (5–15% less rain than present-day), a greater occurrence of droughts ( [[#Taylor--2018|Taylor et al., 2018]] ) along with associated impacts on agricultural production and yield in the region ( [[#Gamble--2017|Gamble et al., 2017]] ; [[#Hoegh-Guldberg--2019|Hoegh-Guldberg et al., 2019]] ; [[#Nicolas--2020|Nicolas et al., 2020]] ). Crop suitability modelling on several commercially important crops grown in Jamaica found that even an increase of less than 1.5°C could result in a reduction in the range of crops that farmers may grow ( [[#Rhiney--2018|Rhiney et al., 2018]] ).

Sugar yield in Fiji could decline by 2–14% under projected scenarios ( [[#McGree--2020|McGree et al., 2020]] ). Farmers in some small islands have utilised Indigenous knowledge systems built on local ontology to sharpen their sensitivity to environmental conditions ( [[#Shah--2018|Shah et al., 2018]] ). However, projected climate change across the Pacific could undermine climate-sensitive agricultural livelihoods and exacerbate food insecurity challenges ( [[#McCubbin--2017|McCubbin et al., 2017]] ; [[#Campbell--2021|Campbell et al., 2021]] ).

Projected climate impacts on island agroecosystem services could accentuate a myriad of social and ecological risks ( [[#Campbell--2021|Campbell, 2021]] ). Without proactive farm management practices, the projected impacts of climate change on drought patterns is a major threat to cocoa pollination services ( [[#Arnold--2018|Arnold et al., 2018]] ). Many tropical island agroforestry crops are completely dependent on insect pollination and it is therefore important to understand the climatic drivers of changing conditions related to pollinator abundance. Coastal agroforestry systems in small Pacific islands are vital to national food security but native biodiversity is rapidly declining ( [[#Ticktin--2018|Ticktin et al., 2018]] ). Biodiversity loss from traditional agroecosystems is a major threat to food and livelihoods security in SIDS ( [[#UNEP--2014a|UNEP, 2014a]] ). Additionally, while coastal-lowland salinisation and more frequent flooding attributable to SLR have impacted coastal agriculture on some islands ( [[#Cruz--2017|Cruz and Andrade, 2017]] ; [[#Wairiu--2017|Wairiu, 2017]] ), stronger TCs can sometimes shock island terrestrial food production warranting reconfiguration ( [[#Mertz--2010|Mertz et al., 2010]] ; [[#Duvat--2016|Duvat et al., 2016]] ; [[#Chakrabarti--2017|Chakrabarti et al., 2017]] ). Calls to conserve associated environments and to make terrestrial food production on islands more resilient to climate-driven shocks underscore concern about future food security ( [[#Connell--2013|Connell, 2013]] ; [[#de%20Scally--2014|de Scally, 2014]] ). Implicit in the latter is reversing the decades-long loss of Indigenous knowledge about food production in many island societies and incorporating it into future strategies ( [[#Mercer--2014b|Mercer et al., 2014b]] ; [[#Janif--2016|Janif et al., 2016]] ).

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==== 15.3.4.5 Economies ====

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Small island economies vary greatly in their nature, history/trends and viability under a changed climate. As elsewhere, few small island economies are overseen by governments that are adequately prepared for the economic impacts of climate change over the next few decades ( [[#Connell--2013|Connell, 2013]] ; [[#Hay--2013|Hay, 2013]] ). In particular, the lack of diversity that characterises most small island economies means they are especially vulnerable to global (climate-driven) shocks (Cross-Chapter Box DEEP in Chapter 17), be these the impacts of extreme events or more gradual longer-term change, which makes the maintenance of traditional mechanisms for coping with such shocks in many island societies all the more important ( [[#Granderson--2017|Granderson, 2017]] ; [[#Wilson--2018|Wilson and Forsyth, 2018]] ; [[#Nunn--2019b|Nunn and Kumar, 2019b]] ). As a result, the risk from climate change to economies constitutes a key risk (KR7 in Figure 15.5) in small islands.

Many island environments have been commercially exploited by external interests for much of their recent history. This is especially common for timber, the wholesale removal of forests, especially on tropical islands, exposing land to heavy rain that leads to denudation and increases lowland sedimentation ( [[#Wairiu--2017|Wairiu, 2017]] ; [[#Eppinga--2018|Eppinga and Pucko, 2018]] ). Negative aspects of both processes will be exacerbated by climate change, demonstrating the practical need for reforestation in many island contexts ( [[#Thomson--2016|Thomson et al., 2016]] ). Some small island economies are sustained by extractive industries such as mining, creating dependencies that lead to their environmental impacts being downplayed ( [[#Tserkezis--2016|Tserkezis and Tsakanikas, 2016]] ; [[#Shepherd--2018|Shepherd et al., 2018]] ). It is important to address these impacts as they will add to negative impacts of climate change ( [[#Clifford--2019|Clifford et al., 2019]] ).

Many small island economies are sustained by tourism and have invested heavily in associated infrastructure and capacity building ( [[#Cannonier--2018|Cannonier and Burke, 2018]] ). Some rural island communities have become dependent on tourism to the point that it would be difficult to revert to subsistence living ( [[#Lasso--2018|Lasso and Dahles, 2018]] ). Coast-focused (beach-sea) tourism in island contexts is already being impacted by beach erosion, elevated high SST causing coral bleaching, and associated marine-biodiversity loss, as well as more intense TCs ( [[#Tapsuwan--2015|Tapsuwan and Rongrongmuang, 2015]] ; [[#Parsons--2018|Parsons et al., 2018]] ; [[#Wabnitz--2018|Wabnitz et al., 2018]] ). The COVID-19 pandemic travel disruption significantly affected the tourism sector of Caribbean islands by reducing incomes that would have been used to enhance climate resilience ( [[#Sheller--2020|Sheller, 2020]] ). Many tourism interests downplay the impacts and future risks from climate change ( [[#Shakeela--2015|Shakeela and Becken, 2015]] ), a position that may be borne out by sustained/rising demand for small island vacationing in some locales ( [[#Katircioglu--2019|Katircioglu et al., 2019]] ). A way forward is for island tourism to emphasize its low-carbon and sustainable attributes, and to encourage smaller-scale eco-friendly holiday opportunities ( [[#Lee--2018|Lee et al., 2018]] ), in other words for island nations to embrace a ‘blue economy’ in line with SDG14 to conserve and utilise their oceans for sustainable futures ( [[#Hampton--2020|Hampton and Jeyacheya, 2020]] ; [[#Hassanali--2020|Hassanali, 2020]] ).

Given the high cost of imported goods, especially foodstuffs, larger island jurisdictions are striving to transform their economies to favour locally produced or locally constituted materials that employ local people and reduce their cost of living. The exposure of this component of island economies varies, yet manufacturing/commercial operations are usually found in the lowest-lying areas, often on reclaimed lands. This makes them especially vulnerable to rising sea level, part of a larger issue around the disproportionate exposure of infrastructure on small islands to climate change ( [[#Fakhruddin--2015|Fakhruddin et al., 2015]] ; [[#Kumar--2015|Kumar and Taylor, 2015]] ).

It is challenging to disentangle the role of climate change from that of globalisation and development in recent changes to human livelihoods on small islands, given that the latter have characterised many—especially SIDS—within the last few decades. However, recent climate change is clearly implicated in livelihood deterioration in many island contexts ( [[#Hernandez-Delgado--2015|Hernandez-Delgado, 2015]] ; [[#Nunn--2018|Nunn and Kumar, 2018]] ). For example, livelihood impacts of climate-driven stressors (including shoreline/riverbank erosion, flooding and erratic rainfall) in three Mahishkhocha island chars (river-mouth sand islands of Bangladesh) have been amplified by inadequate/misguided policy ( [[#Saha--2017|Saha, 2017]] ).The subordination of IKLK in favour of external adaptation strategies has accelerated livelihood decline in many island contexts ( [[#Wilson--2018|Wilson and Forsyth, 2018]] ). Although economic and financial development has the potential to reduce environmental (and livelihood) degradation in SIDS ( [[#Seetanah--2019|Seetanah et al., 2019]] ), it is also clear that uneven development can steepen core–periphery disparities, especially in archipelagic contexts, resulting in deteriorating rural/peripheral livelihoods at the expense of improving urban ones ( [[#Wilson--2013|Wilson, 2013]] ; [[#Sofer--2015|Sofer, 2015]] ) and increased rural–urban migration ( [[#Birk--2014|Birk and Rasmussen, 2014]] ; [[#Connell--2015|Connell, 2015]] ).

<div id="15.3.4.6" class="h3-container"></div>

<span id="migration"></span>
==== 15.3.4.6 Migration ====

<div id="h3-9-siblings" class="h3-siblings"></div>

Climate-related migration is considered to be a particular issue for small islands because changes in extreme events and slow-onset changes affect increasingly highly exposed and vulnerable low-lying coastal populations, therefore causing a threat to small island habitability (KR9 in Figure 15.5) ( [[#Storey--2010|Storey and Hunter, 2010]] ; [[#Kumar--2015|Kumar and Taylor, 2015]] ; [[#Duvat--2017b|Duvat et al., 2017b]] ; [[#Weir--2017|Weir and Pittock, 2017]] ; [[#Hoegh-Guldberg--2018|Hoegh-Guldberg et al., 2018]] ; [[#Mycoo--2018a|Mycoo, 2018a]] ; [[#Rasmussen--2018|Rasmussen et al., 2018]] ). A typology of climate-related migration is provided in Cross-Chapter Box MIGRATE in Chapter 7. It is assumed that climate-related migration will increase in small islands; however, as is the case globally, the causes, form and outcomes are highly context specific. Types of climate-related migration occur across a continuum of agency from involuntary displacement at one end to voluntary movement to strategically reduce risks and planned resettlement at the other end ( [[#15.5.1|Section 15.5.1]] , also see Chapter 7; [[#Birk--2014|Birk and Rasmussen, 2014]] ; [[#Betzold--2015|Betzold, 2015]] ; McNamara and Des Combes, 2015; [[#Gharbaoui--2016|Gharbaoui and Blocher, 2016]] ; [[#Stojanov--2017|Stojanov et al., 2017]] ; [[#Weir--2020|Weir, 2020]] ).

Studies do not provide sufficiently robust evidence to attribute the various forms of migration to anthropogenic climate change directly on small islands or to accurately estimate the current number of climate-related migrants (see Chapter 7). Climate events and conditions strongly interact with other environmental stressors and economic, social, political and cultural reasons for migrating ( ''robust evidence, high agreement'' ) ( [[#Birk--2014|Birk and Rasmussen, 2014]] ; [[#Campbell--2014|Campbell and Warrick, 2014]] ; [[#Laczko--2014|Laczko and Piguet, 2014]] ; Marino and [[#Lazrus--2015|Lazrus, 2015]] ; [[#Connell--2016|Connell, 2016]] ; [[#Weber--2016b|Weber, 2016b]] ; [[#Stojanov--2017|Stojanov et al., 2017]] ; [[#Cashman--2019|Cashman and Yawson, 2019]] ).

Despite difficulties with attribution, the literature establishes that climate variability and extreme events and broad environmental pressures have contributed to some degree to human mobility on small islands over time ( ''medium evidence, high agreement'' ) ( [[#Birk--2014|Birk and Rasmussen, 2014]] ; [[#Campbell--2014a|Campbell, 2014a]] ; [[#Campbell--2014|Campbell and Warrick, 2014]] ; [[#Donner--2015|Donner, 2015]] ; [[#Kelman--2015a|Kelman, 2015a]] ; [[#Connell--2016|Connell, 2016]] ; [[#Stojanov--2017|Stojanov et al., 2017]] ; [[#Barnett--2018|Barnett and McMichael, 2018]] ; [[#Martin--2018|Martin et al., 2018]] ) and these studies can provide analogues from which to inform climate-migration responses ( [[#Birk--2014|Birk and Rasmussen, 2014]] ; [[#Kelman--2015a|Kelman, 2015a]] ; [[#Connell--2016|Connell, 2016]] ).

Similarly, studies do not provide robust evidence to project how the full range of climate drivers may influence migration patterns on small islands into the future, although studies are emerging that estimate populations affected as a consequence of projected SLR. [[#Rasmussen--2018|Rasmussen et al. (2018)]] estimated current populations of the world that are potentially subject to permanent inundation from projected local mean SLR associated with global mean surface temperature stabilisation targets of 1.5°C, 2.0°C and 2.5°C occurring in 2100. For the affected land area and population, this analysis included a subset of 58 SIDS, as defined by the United Nations, for which the results are shown in Table 15.4.

'''Table 15.4 |''' Global mean sea level rise (SLR) at 2100 projections and associated population of SIDS exposed to permanent inundation for global mean surface temperature stabilisation targets of 1.5°C, 2.0°C and 2.5°C. [[#Rasmussen--2018|Rasmussen et al. (2018)]] .

{| class="wikitable"
|-
! Stabilised Warming at 2100 a

! colspan="2"| 1.5°C

! colspan="2"| 2.0°C

! colspan="2"| 2.5°C

|-
! ''Percentile''

! ''50th''

! ''5th–95th''

! ''50th''

! ''5th–95th''

! ''50th''

! ''5th–95th''

|-
| Global mean SLR (cm) by percentile b

| 48

| 28–82

| 56

| 28–96

| 58

| 37–93

|-
| SIDS population exposure (thousands) by percentile c

| 400

| 300–560

| 420

| 300–640

| 430

| 320–630

|}

Notes:

(a) Above pre-industrial level.

(b) Values are centimetres above 2000 current-era baseline.

(c) Potentially affected population due to local mean SLR. Local mean SLR projections used for individual SIDS take account of variations from the global mean due to factors such as glacial isostatic adjustment, gravitational changes from ice melting, deltaic subsidence and tectonic movements.

The aggregate figures of population that could potentially be affected by permanent inundation shown in Table 15.4 and Figure 15.3 mask important differences in relative exposure between individual SIDS. Further, population affected by permanent inundation does not take into account the change in the frequency of ESL events and associated water-level attenuation (as per [[#Vafeidis--2019|Vafeidis et al., 2019]] ), nor does it account for adaptation measures that may alleviate impacts, future population growth or the extent to which populations could adaptively migrate ( [[#15.5.3|Section 15.5.3]] ). However, the analysis by [[#Rasmussen--2018|Rasmussen et al. (2018)]] shows that comparatively small changes in mean sea level can result in large increases in the frequencies of ESL events and, hence, the risk of coastal flooding of inhabited land, suggesting many areas of SIDS may become uninhabitable well before the time of permanent inundation (see also studies referenced in [[#15.3.3.1.1|Section 15.3.3.1.1]] ). A similar conclusion is drawn by [[#Kulp--2019|Kulp and Strauss (2019)]] , who show that land area home to 10% or more of the population of many SIDS is at risk of chronic coastal flooding or permanent inundation by 2100.

[[#Duvat--2021a|Duvat et al. (2021a)]] employed an integrated systems approach to analyse future risk to habitability in atoll islands, taking into account changes in various ocean and atmospheric climate drivers and a moderate adaptation scenario (i.e., adaptation responses that remain similar in nature and magnitude to currently observed responses). They found that, compared to present-day risk, additional risk to habitability in Male’, Maldives, and Fongafale, Tuvalu, is minimal under a low emissions scenario (RCP2.6) at 2050, although it may become moderate for Male and high for Fongafale by 2090. Under a worse-case emissions scenario (RCP8.5), future risk to habitability in these two urban islands may increase slightly in 2050, but may increase to moderate-to-high (for Male’) and high-to-very high (for Fongafale) by 2090.

Even where settlement locations and livelihoods remain secure, an increase in health diseases, decrease in the availability of potable water and increasing exposure to extreme events may reduce habitability ( [[#15.3.4.9.2|Section 15.3.4.9.2]] ; [[#Campbell--2014|Campbell and Warrick, 2014]] ; [[#Storlazzi--2018|Storlazzi et al., 2018]] ). For example, the Fijian coastal community of Vunidogoloa made the decision to relocate in response to regular inundation during high tides. Raising houses on stilts and constructing a seawall failed to prevent regular flood damage to buildings and the entire community eventually relocated as a ‘last resort’ adaptation measure to a site within customary land. The availability of customary land for the new site was a key factor of success in this relocation example although this will not guarantee success in every case as relocation may expose communities to new risks (McNamara and Des Combes, 2015; [[#Piggott-McKellar--2019a|Piggott-McKellar et al., 2019a]] ).

<div id="15.3.4.7" class="h3-container"></div>

<span id="culture"></span>
==== 15.3.4.7 Culture ====

<div id="h3-10-siblings" class="h3-siblings"></div>

Small island societies have developed IKLK-based responses to living in dynamic environments susceptible to climate variability and extremes, which are based in broader systems of culture and heritage ( ''high confidence'' ) ( [[#Barnett--2010|Barnett and Campbell, 2010]] ; [[#Lazrus--2015|Lazrus, 2015]] ; [[#Nunn--2017b|Nunn et al., 2017b]] ; [[#Bryant-Tokalau--2018b|Bryant-Tokalau, 2018b]] ; [[#Nalau--2018b|Nalau et al., 2018b]] ; [[#Perkins--2018|Perkins and Krause, 2018]] ). As expanded upon in [[#15.6.5|Section 15.6.5]] , cultural resources are thought to play an important role in climate change adaptation on small islands through contributing to adaptive capacity and resilience ( [[#McMillen--2014|McMillen et al., 2014]] ; [[#Petzold--2015|Petzold and Ratter, 2015]] ; [[#Nunn--2017b|Nunn et al., 2017b]] ; [[#Warrick--2017|Warrick et al., 2017]] ; [[#Falanruw--2018|Falanruw, 2018]] ; [[#Mondragón--2018|Mondragón, 2018]] ; [[#Neef--2018|Neef et al., 2018]] ; [[#Parsons--2018|Parsons et al., 2018]] ; [[#Perkins--2018|Perkins and Krause, 2018]] ; [[#Hagedoorn--2019|Hagedoorn et al., 2019]] ; 2020a) ( ''robust evidence, medium agreement)'' . Thus, loss of culture (KR8 in Figure 15.5) threatens adaptive capacity.

Some studies from the Pacific suggest that climate-migration linked to reduced habitability ( [[#15.3.4.6|Section 15.3.4.6]] ) can have particularly severe cultural implications in a small island context where community solidarity and cohesion linked to place-based identity are important aspects of adaptive capacity ( [[#Hofmann--2014|Hofmann, 2014]] ; [[#Lazrus--2015|Lazrus, 2015]] ; [[#Warrick--2017|Warrick et al., 2017]] ). In the Federated States of Micronesia, land is owned through the matrilineal system and hence puts women at the centre of decision-making. The deterioration and loss of land (through saltwater intrusion, flooding, drought, erosion) not only can lead to economic deprivation but it also compromises cultural identities: ‘Where land signifies political, social, and economic well-being, becoming bereft of land cuts off an important thread of people’s sense of belonging’ ( [[#Hofmann--2017|Hofmann, 2017]] , p. 82) particularly for Chuuk women. Land degradation and loss involves the ‘interruption to the matrilineal transmission of land’ ( [[#Hofmann--2017|Hofmann, 2017]] ; p. 82), the loss of identities, relationships and their customary authority.

The unquantifiable and highly localised cultural losses resulting from climate drivers are less researched and less acknowledged in policy than physical and economic losses ( [[#Karlsson--2015|Karlsson and Hovelsrud, 2015]] ; [[#Thomas--2018a|Thomas and Benjamin, 2018a]] ). In the Bahamas, prolonged displacement of the entire population of Ragged Island following Hurricane Irma (2017) highlighted the cultural losses that can result from climate-induced displacement from ancestral homelands. Threats to identity, sense of place and community cohesion resulted from displacement, although all were important foundational features of the Islanders’ self-initiated rehabilitation efforts and eventual return. Nonetheless, non-economic losses were not accounted for by policy addressing displacement ( [[#Thomas--2018a|Thomas and Benjamin, 2018a]] ). In the case of Monkey River Village in Belize, coastal erosion is threatening the community’s cemetery. Residents place significant spiritual and emotional value on the cemetery, which serves important community functions, and, thus, threats to it are perceived to be serious and necessary to be taken into account in any planned response ( [[#Karlsson--2015|Karlsson and Hovelsrud, 2015]] ). A similar situation exists on Carriacou in the West Indies where culturally and historically significant archaeological sites are being lost due to coastal erosion caused by a combination of sand mining and extreme climate-ocean events exacerbated by SLR ( [[#Fitzpatrick--2006|Fitzpatrick et al., 2006]] ).

Population and settlement concentration in coastal areas and high exposure to climate-driven coastal hazards on small islands mean that threats to tangible cultural heritage (archaeological sites, buildings, historic sites, UNESCO World Heritage Sites etc.) are high ( [[#Marzeion--2014|Marzeion and Levermann, 2014]] ; [[#Reimann--2018|Reimann et al., 2018]] ), although few studies examine this issue specifically in a small island context. On the island of Barbuda, archaeological sites containing important information on historical ecology and climatic shifts are at risk from coastal erosion and hurricanes. This loss of heritage represents identity loss, as “learning about the past is a crucial exploration of self that grounds and connects people to places” ( [[#Perdikaris--2017|Perdikaris et al., 2017]] ; p. 145). Losses and damages to heritage sites may also impact tourism and thus have significant economic impacts for narrow small island economies ( [[#15.3.4.5|Section 15.3.4.5]] ).

<div id="15.3.4.8" class="h3-container"></div>

<span id="transboundary-risksissues"></span>
==== 15.3.4.8 Transboundary Risks/Issues ====

<div id="h3-11-siblings" class="h3-siblings"></div>

Inter-regional transboundary impacts are those generated by processes originating in another region or continent well beyond the borders of an individual archipelagic nation or small island. Intra-regional transboundary impacts originate from a within-region source (e.g., the Caribbean). Some transboundary processes may have positive effects on the receiving small island or nation, although most that are reported have negative impacts (Table 15.5).

'''Table 15.5 |''' Summary of inter- and intra-regional transboundary risks and impacts on small islands.

{| class="wikitable"
|-
! '''Transboundary risks/issues'''

! '''Small island examples'''

! '''Reference'''

|-
| Large ocean waves from distant sources

| Unusually large deep ocean swells generated from sources in the mid- and high latitudes by extratropical cyclones (ETCs) cause considerable damage on the coasts of small islands thousands of kilometres away in the tropics. Impacts include inundation of settlements, infrastructure, and tourism facilities as well as coastal erosion. These waves can propagate to and influence reef islands in equatorial areas not usually exposed to high-energy waves.

Examples of extratropical swell waves causing flooding and inundation have been reported throughout the Pacific (French Polynesia, Fiji, Micronesia, the Marshall Islands, Kiribati, Papua New Guinea and the Solomon Islands). Modelling of future wave climates has been carried out for 25 tropical Pacific islands, and results suggests that December–February extreme wave heights will decrease for most islands by 2100 under both an RCP4.5 and RCP8.5 scenario, although the frequency of the large winter wave events may increase around the Hawaiian Islands. In the Caribbean, northerly swells affecting the islands have been recognised as a significant coastal hazard. They cause considerable seasonal damage to beaches, marine ecosystems and coastal infrastructure throughout the region.

| [[#Hoeke--2013|Hoeke et al. (2013)]] ; [[#Smithers--2014|Smithers and Hoeke (2014)]] ; [[#Shope--2016|Shope et al. (2016)]] ; [[#Canavesio--2019|Canavesio (2019)]] ; [[#Wandres--2020|Wandres et al. (2020)]]

[[#Jury--2018|Jury (2018)]]

|-
| Transcontinental dust clouds and their impacts

| The transport of airborne Saharan dust across the Atlantic into the Caribbean has been intensively studied. In the West African Sahel, where drought has been persistent since the mid-1960s, analysis has shown that there have been remarkable changes in dust emissions since the late 1940s. Variability in Sahel dust emissions may be related not only to droughts, but also to changes in the North Atlantic Oscillation (NAO), North Atlantic SST and the Atlantic Multidecadal Oscillation (AMO). The frequency of dust storms has been on the rise during the last decade. Forecasts suggest that their incidence will increase further. Transboundary movement of Saharan dust into the island regions of the Caribbean and the Mediterranean has been associated with human health problems including asthma cases in the Caribbean, cardiovascular morbidity in Cyprus and pulmonary disease in the Cape Verde islands.

| [[#Prospero--2003|Prospero and Lamb (2003)]] ; [[#Goudie--2014|Goudie (2014)]] ; [[#Schweitzer--2018|Schweitzer et al. (2018)]] ; [[#Goudie--2020|Goudie (2020)]] ; [[#Middleton--2008|Middleton et al. (2008)]] ; [[#Martins--2009|Martins et al. (2009)]] ; [[#Akpinar-Elci--2015|Akpinar-Elci et al. (2015)]] ; [[#Sakhamuri--2019|Sakhamuri and Cummings (2019)]]

|-
| Influx of Sargassum from distant sources

| Since 2011, the Caribbean region has witnessed unprecedented influxes of the pelagic seaweed Sargassum. These extraordinary sargassum ‘blooms’ have resulted in mass deposition of seaweed on beaches throughout the Lesser Antilles, with damage to coastal habitats, mortality of seagrass beds and associated corals, as well as consequences for fisheries and tourism. This recent phenomenon has been linked to climate change as well as the possible influence of nutrients from Amazon River floods and/or Sahara dust.

| [[#van%20Tussenbroek--2017|van Tussenbroek et al. (2017)]] ; [[#Oviatt--2019|Oviatt et al. (2019)]]

Franks et al. (2016); [[#Putman--2018|Putman et al. (2018)]]

|-
| Large-scale changes in the distribution of fisheries resources

| Ocean warming and other climatic phenomena (e.g., ENSO events and Indian Ocean Dipole) have been linked to observed oceanic shifts in tuna distribution with significant impacts on revenue for vulnerable small island states that depend on fisheries licences (e.g., 98% of national income in Tokelau, 66% of national income in Kiribati). The projected eastward redistribution of skipjack and yellowfin tuna due to climate change is expected to reduce the total tuna catch within the combined Exclusive Economic Zones of the 10 Pacific Island Countries and territories (PICTs) where most purse-seine activity occurs by approximately 10% by 2050. Projected increases in tuna biomass have been anticipated for Ascension Island and Saint Helena in the South Atlantic.

| [[#Bell--2018|Bell et al. (2018)]] ; [[#SPC--2019|SPC (2019)]] ; [[#Oremus--2020|Oremus et al. (2020)]] ; [[#Bell--2021|Bell et al. (2021)]] ; [[#Townhill--2021|Townhill et al. (2021)]]

|-
| Movement and impact of introduced and invasive species across boundaries

| The spread of IAS is regarded as a significant transboundary threat to the health of biodiversity and ecosystems worldwide.

The extent to which IAS (both animals and plants) successfully establish themselves at new locations in a changing climate will be dependent on many variables, but non-climate factors such as transmission pathways, suitability of the destination, ability to compete and adapt to new environments, and susceptibility to invasion of host ecosystems are deemed to be critical. Modelling studies have been used to project the future ‘invisibility’ of small island ecosystems subject to climate change and therefore to anticipate marine and terrestrial habitat degradation in the future.

Evidence suggests that hurricanes may have hastened the spread of highly invasive Indo-Pacific lionfish ( ''Pterois volitans'' ) throughout the Caribbean in recent years. Two IAS, the Common Green Iguana ( ''Iguana iguana'' ) and Cuban Treefrog ( ''Osteopilus septentrionalis'' ) were reported in the Caribbean island of Dominica, following the passage of TC Maria in 2017. Observations 7 months after the hurricane, within close proximity to ports, suggest that these animals were stowaways on ships or within relief containers.

| [[#Russell--2017|Russell et al. (2017)]]

[[#Vorsino--2014|Vorsino et al. (2014)]] ; [[#Taylor--2016b|Taylor and Kumar (2016b)]]

[[#Johnston--2015|Johnston and Purkis (2015)]] ; van den Burg et al. (2020)

|-
| Spread of pests and pathogens within and between island regions

| Increased climate instability has contributed to the emergence and spread of serious diseases carried by mosquitoes such as dengue, chikungunya and Zika. The incidence and severity of mosquito-borne diseases have increased significantly in Pacific, Indian Ocean and Caribbean islands during the past 10 years, which calls for a better understanding of how climate change is shaping disease prevalence and transmission.

Rising sea temperatures are thought to increase the frequency of disease outbreaks affecting reef buildings. Of the range of bacterial, fungal and protozoan diseases known to affect stony corals, many have explicit links to temperature. Global projections suggest that disease is as likely to cause coral mortality as bleaching in the coming decades at many localities, with effects occurring earlier at sites in the Caribbean compared to the Pacific and Indian oceans. Model hindcasts suggest that climate-driven changes in SST as well as extreme heatwave events have all played a significant role in the spread of white-band disease throughout the Caribbean.

Global food security is threatened by climate-related increases in crop pests and diseases. Black Sigatoka disease of bananas has recently completed its invasion of Latin American and Caribbean banana-growing areas. Infection risk has increased by a median of 44.2% across the Caribbean since the 1960s, due to increasing canopy wetness and improving temperature conditions for the pathogen.

| [[#Cao-Lormeau--2014|Cao-Lormeau and Musso (2014)]] ; [[#Caminade--2017|Caminade et al. (2017)]] ; [[#Pecl--2017|Pecl et al. (2017)]] ; [[#Filho--2019|Filho et al. (2019)]]

[[#Maynard--2015|Maynard et al. (2015)]] ; [[#Randall--2015|Randall and van Woesik (2015)]]

[[#Bebber--2019|Bebber (2019)]]

|-
| Human migration and displacement

| Currently there is limited empirical evidence that long-term climate change is driving transboundary human migration from islands; however, following Hurricane Maria, Puerto Rico witnessed ‘depopulation’ of 14% in only 2 years as a result of emigration to the US mainland.

| [[#Campbell--2014a|Campbell (2014a)]] ; [[#Melendez--2017|Melendez and Hinojosa (2017)]]

|-
| Transboundary risks to island food security. COVID-19 caused disruptions to food supply and disaster risk management operations

| While SIDS are a diverse group of nations, most share such characteristics as limited land availability, insularity and susceptibility to natural hazards that make them particularly vulnerable to global environmental and economic change processes leading to regional food insecurity. The Pacific Islands Forum Secretariat (PIFS) has established a transboundary Framework for Action on Food Security, that promotes cooperation, investments, research and development, capacity-building, and adaptation to mitigate climate change threats.

| [[#Connell--2013|Connell (2013)]] ; [[#Islam--2020|Islam and Kieu (2020)]] ; [[#Sheller--2020|Sheller (2020)]]

|}

<div id="15.3.4.9" class="h3-container"></div>

<span id="key-risks-in-small-islands"></span>
==== 15.3.4.9 Key Risks in Small Islands ====

<div id="h3-12-siblings" class="h3-siblings"></div>

<div id="15.3.4.9.1" class="h4-container"></div>

<span id="key-risk-approach"></span>
===== 15.3.4.9.1 Key risk approach =====

<div id="h4-9-siblings" class="h4-siblings"></div>

This section builds on cross-chapter work led by [[IPCC:Wg2:Chapter:Chapter-16|Chapter 16]] aimed at identifying and assessing KRs across sectors and regions ( [[IPCC:Wg2:Chapter:Chapter-16#16.5|Section 16.5]] and SM16). KRs are the risks of most pressing concern that are caused or exacerbated by climate change in a given region. A KR is defined as a ‘potentially’ severe risk, which can either be already severe or projected to become severe in the future, as a result of (a) changes in associated climate-related hazards and/or the exposure and/or vulnerability of natural and human systems to these hazards, and/or of (b) the adverse consequences of adaptation or mitigation responses to the risk. In line with the guidelines used in the WGII AR6, the identification of KRs in small islands is based on the chapter authors’ expert judgement, using scientific literature and five types of criteria: (1) importance of the affected system or dimension of the system, which is a value judgement left to readers to make; (2) magnitude of adverse consequences, based on their pervasiveness, degree and irreversibility, and on the potential for impact thresholds and cascading effects across the system; (3) likelihood of adverse consequences, although this probability is rarely quantifiable for small islands due to limited downscaled data at a small island level; (4) temporal characteristics of the risk, including its period of emergence, persistence over time and trend; and (5) ability to respond to the risk, with the severity of the risk being inversely proportional to this ability.

<div id="15.3.4.9.2" class="h4-container"></div>

<span id="key-risks-in-small-islands-1"></span>
===== 15.3.4.9.2 Key risks in small islands =====

<div id="h4-10-siblings" class="h4-siblings"></div>

Slow-onset climate and ocean changes, and changes in extreme events, are expected to cause and/or to amplify nine KRs in small islands, through both direct (e.g., decrease in rainfall will increase water insecurity) and indirect, that is, cascading effects: For example, loss of terrestrial biodiversity and ecosystem services will increase water insecurity, which will in turn cause the degradation of human health and well-being (Figure 15.5, Table 15.6 and SM16).

'''Table 15.6 |''' Adaptation options per key risk in small islands. This table summarises risk-oriented adaptation options, their level of implementation, enablers and effectiveness in reducing exposure and vulnerability, co-benefits and disbenefits in small islands. For KR2 (submergence of reef islands), not included, adaptation options are the same as for KR5.

{| class="wikitable"
|-
! Key risks

! colspan="2"| Risk-oriented adaptation options

! Evidence and agreement

! Implementation

! Key enablers

! Reduction of exposure and vulnerability

! Co-benefits

! Disbenefits

|-
| rowspan="5"| KR1. Loss of marine and coastal biodiversity and ecosystem services

| rowspan="2"| EbA measures (15.4.4)

| MPAs; paired terrestrial and MPAs

| ''Medium evidence, low agreement'' with regard to climate change adaptation and benefits

| Widespread across small islands, with climate resilience being a target of some MPAs

| Strong governance and sufficient financial resources

| Reduces the ecosystem exposure to human disturbances, increasing their resistance and resilience to climate events

| For biodiversity, food supply, economics, human health and well-being

|
|-
| Active restoration of coastal and marine ecosystems

| ''Limited evidence, low agreement'' with regard to long-term success

| Mostly small-scale: replanting of mangroves, seagrasses and beach vegetation; transplantation of corals; beach nourishment

| Funding: adaptation taxes and levies imposed on tourism; blue bonds; public–private partnerships

| Reduces the vulnerability of natural ecosystems by increasing their resilience

| Improved water quality; reduction in coastal erosion and flood risks; economic benefits

|
|-
| Hard protection (15.5.1)

| Hard structures designed to enhance marine biodiversity

| ''Medium evidence, medium agreement''

| Artificial reefs

| Funding: adaptation and environmental taxes and levies, with ''limited evidence'' of direct reinvestment in conservation and management

| Uncertainty on reduction of exposure and vulnerability of marine ecosystems; reduces the exposure of population and infrastructure to coastal risks

| For food supply, economies (tourism), human health and well-being

|
|-
| Diversifying livelihoods (15.5.6)

| Diversifying fisheries livelihoods (e.g., to aquaculture and tourism), changing fishing grounds and/or target species

| ''Limited'' to ''medium evidence'' , ''medium agreement''

| Examples in the Caribbean region and in the Pacific and Indian Oceans

| Improved governance and cooperation (e.g., through regional strategies); weather insurance to enhance resilience

| Reduces exposure and vulnerability of livelihoods through the diversification of income and spreading of risks; targeting less offshore pelagic species reduces exposure of coastal habitats to overfishing

| Sustainably managed fisheries, improved food and income security, greater economic and social resilience

|
|-
| Reef-to-ridge ecosystem management (Figure 15.4)

| Improved land use as a driver of marine ecosystem health, including better management of forests, nutrients and wastewater upland catchments

| ''Limited evidence, medium agreement''

| Mostly in the Caribbean region and Pacific

| Improved governance

| Reduces the exposure of coral reefs to human degradation, increasing their resilience

| Improved ecosystem protection services (e.g., against flooding, landslides and mudflows), biodiversity, human health and livelihoods

|
|-
| rowspan="5"| KR3. Loss of terrestrial biodiversity and ecosystem services

| Decreased deforestation (15.5.4)

|
| ''Limited'' to ''medium evidence, high agreement''

| Mostly in the Caribbean region and Pacific

| National determined contributions (NDCs), external and long-term funding, engagement of local landowners and resolution of land ownership issues, gender-sensitive participation

| For example, increase in forest extent, reduction in human exposure to natural disasters (hurricanes, landslides), improvement in vulnerability assessment scores

| Increased connectivity between forest fragments, reduced erosion, improved water supply and quality, improved human health and sanitation, improved livelihoods and soil health; decreased poverty; supports global mitigation

|
|-
| Increased reforestation (native species) (15.5.4)

| Towards habitat connectivity, heterogeneity and diversity

| ''Medium evidence, high agreement''

| Relatively widespread, with examples in the Caribbean region and Pacific

| NDC, funding, technical assistance, supply materials, provision of land, awareness raising, enforcement of policies, sense of shared responsibility, inclusion of IKLK, social capital

| Generally ''limited evidence'' , lack of long-term monitoring

| Increased DRR; fewer floods and landslides; reduced erosion; increased human health and well-being; increased quality of ecosystem services; increased adaptive capacity; supports global mitigation

|
|-
| EbA (15.5.4)

| Agroforestry and other silvicultural/agroecological practices (e.g., climate-smart agriculture)

| ''Medium evidence, high agreement''

| Widespread in the Caribbean region and Pacific Ocean

| NDC, shared access and benefit, local knowledge and training, farmers, private sector for developing technology, financing, data availability; political, institutional and socioeconomic conditions

| Limited examples, some increases in adaptive capacity

| Improved climate change awareness, increased well-being, improved gender equity, improved productivity and livelihoods

|
|-
| Watershed management/conservation (15.5.4)

| Reforestation, slope revegetation

| ''Medium evidence, high agreement''

| Widespread (e.g., in the Caribbean region and Pacific Ocean)

| Less socially and politically acceptable than engineering solutions; communication and trust between stakeholders; sustainable financing mechanisms; island remoteness barrier to logistical implementation

| Yes, through improved water security, reduced adaptation costs, reduced vulnerability to drought

| DRD, improved climate change awareness, increased water security and quality, reduced run-off and sedimentation, increased well-being and financial stability

|
|-
| Ridge-to-reef ecosystem management (Figure 15.4)

| Improved land use as a driver of terrestrial ecosystem health

| ''Medium evidence, high agreement''

| See above

| See above

| ''Limited but slowly increasing evidence'' to date

|
|-
| rowspan="2"| KR3. Loss of terrestrial biodiversity and ecosystem services

| Increasing the connectivity of protected areas (PAs) across elevation/climatic gradients to facilitate climate-driven redistribution of species (Figure 15.4)

| Establishment of new PAs, forested migration corridors across elevation/climatic gradients, improving landscape connectivity by permanent protection of stepping stones

| ''Very limited evidence, high agreement''

| Low degree of new implementations due to terrain limitations combined with competition from human land use needs; large variation in PA coverage among islands

| Conservation of larger areas of forest habitat surrounding PAs, reforestation of degraded areas, increasing and enforcement of forest cover within PAs, policies towards the coordination of conservation actions/partnerships, incorporation of ‘Other Effective area-based Conservation Measures’ (OECMs)

| Yes, especially if landscape connectivity is improved (migration corridors)

| Improved water security, improved coastal ecosystem health, greater resiliency and recovery from wildfires, reduced pollution, DRR

| May facilitate movement of IAS

|-
| Eradication of IAS (15.3.3.3)

|
| ''Robust evidence, high agreement''

| Widespread (&gt;700 islands)

| Integration of changing climate conditions within ongoing prevention, control and eradication strategies, prevention via ongoing vigilance and biosecurity via quarantine, control and monitoring of incoming cargo and goods into islands

| Yes, positive demographic and distributional responses of native species following eradication of IAS

| Food security, protection of ecosystem health and services, increased livelihood security

| A few native species harmed by eradication process

|-
| rowspan="4"| KR4. Water insecurity

| Rainwater harvesting (15.3.4.3)

|
| ''Robust evidence, high agreement''

| Widespread across small islands (e.g., Jamaica, Barbuda, Solomon Islands)

| Sociocultural and financial

| Yes

| Biodiversity (watershed protection); health; economic (reduced dependence on public supply); food security

| Dependent on mode of implementation. Nothing mentioned in the chapter.

|-
| Desalination (15.6.1)

|
| ''Limited evidence, high agreement''

| Relatively limited (e.g., Maldives)

| Financial

| Yes

| Health; economic (reduced dependence on public supply)

| Energy intensive (carbon footprint)

|-
| Reforestation (15.5.4)

|
| ''Medium evidence, high agreement''

| Examples reported in the Caribbean and Pacific (e.g., Fiji, Papua New Guinea)

| Governance–whole-of-island approaches foster integrated management practices in small islands

| Yes, through supporting wetland-oriented tourism

| Economic (agroforestry); biodiversity (watershed restoration); food security; DRR

| rowspan="2"| Dependent on mode of implementation. Nothing mentioned in the chapter.

|-
| PA management (terrestrial) (15.5.4)

|
| ''Medium evidence, high agreement''

| Widespread across small islands (e.g., Samoa, Jamaica, Haiti, Grenada)

| Financial/governance

| Yes, through soil stabilisation and sequestration of pollutants

| Biodiversity (forest conservation); DRR

|-
| rowspan="5"| KR5. Destruction of settlements and infrastructure

| Hard protection (15.5.1)

|
| ''Medium agreement, limited evidence'' with regard to climate change adaptation and success

| Widespread in both urban and rural areas of the Caribbean, Pacific and Indian Oceans

| External funding; sociocultural (meets the preference of the population); political–institutional (e.g., supported by business-as-usual approach of coastal risks); technical (requires materials and skills)

| Reduces exposure in some places but not in others; increases vulnerability

| ''Limited evidence'' of co-benefits

| Beach loss; erosion acceleration; ecosystem degradation through material extraction; increased SLR impacts

|-
| Accommodation (15.5.2)

|
| ''Limited evidence'' with regard to climate change adaptation and success

| Relatively limited

| Technological, financial, institutional, sociocultural

| ''Limited evidence'' to date

| Maintains the functionalities of coastal systems and allows their maintenance through landward migration, under SLR

|
|-
| Advance with land raising and/or through the creation of artificial islands (15.5.2)

|
| ''Limited evidence'' with regard to climate change adaptation (driven by population growth in the Maldives)

| Limited (e.g., Hulhumalé, Maldives)

| Technological, financial, institutional, sociocultural, high potential in urban (compared to rural) areas

| Reduces population exposure where high standard as in Hulhumalé, Maldives

| Offers new land for economic development, generates revenues through sale or lease of land in urban areas

| Widespread ecosystem destruction, increased negative impacts of SLR

|-
| Migration including planned resettlement (15.5.3)

|
| ''Limited evidence, low agreement'' with regard to climate change adaptation

| Village-scale planned resettlement supported by government policy/legislation in the Pacific

| Participatory inclusion of all social groups; financial (for small and remote communities); social–cultural connections; strong governance frameworks; enabling legislation; land availability or ownership; conditions in receiving locations; technical support

| Reduced exposure locally; has created new vulnerabilities at some locations by bearing significant economic cost, impacting social capital and reducing access to services

| New livelihood opportunities

| Loss of cultural heritage, impacts on receiving communities

|-
| EbA measures (15.4.4)

|
| ''Medium agreement, medium evidence''

| Increasingly experienced; includes artificial reefs, beach nourishment and vegetation (including mangrove) restoration

| Environmental/physical conditions; social acceptability; technical capacities (enhanced by external support); funding; inclusion in national adaptation policies

| ''Limited evidence'' to date

| Biodiversity strengthening; increased food supply; increased human health and well-being

|
|-
| KR6. Health degradation

| Increasing public awareness of health risks associated with climate change; providing training to health sector staff; improving reliability and safety of water storage practices (15.6.2)

|
| ''Limited evidence''

| Few examples

| Financial and human resources to implement options; early warning and response systems; integrating climate services into health decision-making systems; public uptake and buy in; improving health data collection systems

| Primarily reduces vulnerability

| Increased water security

|
|-
| rowspan="5"| KR7. Economic decline and livelihood failure

| Circular migration (15.5.3)

|
| ''Limited evidence'' with regard to climate change adaptation (mostly driven by economic or social factors)

| Examples in Tuvalu from outer to capital atoll and locations overseas

| Labour and education opportunities in Funafuti, Tuvalu, and overseas

| Yes, on Nanumea Atoll, Tuvalu

| Job and education for migrants

|
|-
| Diversifying livelihoods (15.5.6)

|
| ''Limited'' to ''medium evidence, low agreement''

| Observed in the Caribbean region and Pacific

| Use of IKLK and changing fishing areas; investment in technology and education

| Yes, in documented places (e.g., Antigua, Vanuatu, Madagascar, Dominican Republic)

| Reduction of pressure on previous fishing areas

| Greater catch putting increasing pressure on fish stock

|-
| Improved technology and equipment/training (15.5.6)

|
| ''Limited evidence, medium agreement''

| Examples in the Caribbean region and Pacific

| Investments in technologies and education (e.g., irrigation technologies, growing salt-tolerant crops and relocating crop cultivation in Jamaica)

| Yes, in documented places

| New technologies and education strengthening

|
|-
| Livestock husbandry (15.5.6)

|
| ''Limited evidence''

| Limited (e.g., small-scale livestock husbandry in Jamaica)

| Farm inputs and investments in technologies and education

| No evidence to date. Limited examples of successful livestock husbandry only in Jamaica

| Investments in farm inputs

|
|-
| Adaptive finance/education (15.5.6)

|
| ''Limited evidence, medium agreement''

| Limited (e.g., in Puerto Rico, women engage in new commercial enterprises that do not rely on traditional coffee supply chains or government assistance)

| Tourism income; investment in education and capacity building; working with nature and EbA

| Yes, reduces risk and avoids negative knock-on effects

| Generates opportunities (e.g., for wetland tourism)

|
|-
| rowspan="2"| KR7. Economic decline and livelihood failure

| Product/market diversification (15.5.6)

| Diversity of crops, gardening in different areas, storage and preservation of foodstuffs, engagement of women in new commercial enterprises

| ''Medium evidence, high agreement''

| Examples in the Caribbean region and Pacific

| Availability of crops and land, new markets

| Reduces vulnerability to tropical cyclones in Fiji and Vanuatu; new markets in Puerto Rico

| Increases food security and improves nutrition; increases income security

|
|-
| Adaptation in tourism policies (15.5.6)

|
| ''Limited evidence, high agreement''

| Limited (e.g., in the British Virgin Islands, policies like adaptation taxes and levies imposed on tourism can provide funding for adaptation measures)

| Tourism regulations and policies that mainstream climate change adaptations; taxes and levies imposed on tourism

| ''Limited evidence'' in reducing vulnerability

|
|-
| rowspan="2"| KR8. Loss of cultural resources and heritage

| Integrating IKLK with Western science to provide integrated approaches to climate change (15.6.5)

|
| ''Medium evidence, high agreement''

| Reported in the Pacific and Caribbean

| Use of IKLK for preparing for disasters and understanding environmental change; social networks in sharing information and helping others; eco-theology increasing people’s awareness of the environment

| Yes, can reduce vulnerability when IKLK supports robust adaptation; No, can increase vulnerability if IKLK no longer provides accurate information

| Can increase climate change information and its understanding in communities, and increase culturally appropriate climate adaptation

| Reports from Vanuatu indicate that IKLK are at times inaccurate (e.g., seasonal calendars, biophysical weather indicators) due to climate change

|-
| Hard protection (15.5.5.1)

|
| ''Medium agreement, limited evidence'' with regard to climate change adaptation and success

| Widespread in protecting cultural sites and villages in both urban and rural areas of the Caribbean, Pacific and Indian Oceans

| External funding; sociocultural (generally meets the preference of the population); political-institutional (e.g., supported by business-as-usual approach of coastal risks); technical (requires materials and skills)

| Reduces exposure in some places but not in others; increases vulnerability

| ''Limited evidence'' of co-benefits

| Beach loss; erosion acceleration; ecosystem degradation through material extraction; increased SLR impacts

|}

These KRs include loss of marine and coastal biodiversity and ecosystem services ( ''high confidence'' ) (KR1; for details on KR coverage, see [[#15.3.3.1|Section 15.3.3.1]] ); submergence of reef islands ( ''low confidence'' ) (KR2; [[#15.3.3.1.1|Section 15.3.3.1.1]] ); loss of terrestrial biodiversity and ecosystem services ( ''high confidence'' ) (KR3; [[#15.3.3.3|Section 15.3.3.3]] ); water insecurity ( ''medium-high confidence'' ) (KR4; [[#15.3.4.3|Section 15.3.4.3]] ); destruction of settlements and infrastructure ( ''high confidence'' ) (KR5; [[#15.3.4.1|Section 15.3.4.1]] ); degradation of human health and well-being ( ''low confidence'' ) (KR6; [[#15.3.4.2|Section 15.3.4.2]] ); economic decline and livelihood failure ( ''high confidence'' ) (KR7; Sections 15.3.4.4 and 15.3.4.5); and loss of cultural resources and heritage ( ''low confidence'' ) (KR8; [[#15.3.4.7|Section 15.3.4.7]] ).

Risk accumulation and amplification through cascading effects from ecosystems and ecosystem services to human systems will likely cause reduced habitability of some small islands ( ''high confidence'' ) identified as the overarching KR (KR9). Habitability is understood as the ability of these islands to support human life by providing protection from hazards which challenge human survival; by assuring adequate space, food and freshwater; and by providing economic opportunities, which contribute to health and well-being—recognising that both supportive ecosystems and sociocultural conditions (i.e., beliefs and values, institutions and governance arrangements, sense of community and attachment to place) play a critical role in habitability ( [[#Duvat--2021a|Duvat et al., 2021a]] ). The reduction of island habitability is expected to cause increased migration, along the afore-mentioned involuntary displacement to planned resettlement spectrum ( [[#15.3.4.6|Section 15.3.4.6]] ), which may eventually lead to population movements from exposed areas and depopulation of some islands. This risk is the highest for atoll nations, where some islands might become uninhabitable over this century ( [[#15.3.4.6|Section 15.3.4.6]] ; [[#Storlazzi--2018|Storlazzi et al., 2018]] ; [[#Duvat--2021a|Duvat et al., 2021a]] ). Despite a lack of literature assessing the risk of reduced habitability in non-atoll islands, the latter are also expected to experience decreased habitability, especially in their coastal areas.

<div id="box-15.1" class="h2-container box-container"></div>

'''Box 15.1 | Key Examples of Cumulative Impacts from Compound Events: Maldives Islands and Caribbean Region'''
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'''Cumulative Impacts of the Compound Events of the 1998–2016 Period in the Maldives Islands'''
Between 1998 and 2016, the Maldives Islands were affected by three major climate events, including the 1997–1998 ENSO event, the 2007 flood event and the 2016 ENSO event, and by one tectonic event, the 2004 Indian Ocean tsunami ( [[#Morri--2015|Morri et al., 2015]] ). These events illustrate the cumulative and cascading risks that a series of events may cause in reef-dependent atoll contexts (Figure Box 15.1).

[[File:9e99beca64cbd208d342f2a881860f31 IPCC_AR6_WGII_Figure_15_Box_15_1_1.png]]

'''Figure Box 15.1.1 |''' '''Cascading and cumulative impacts of the compound events of the 1998–2016 period in the Maldives Islands.'''

The 1997–1998 ENSO event was severe in the Maldives and as a result the living coral cover dropped to &lt;10% ( [[#Bianchi--2003|Bianchi et al., 2003]] ). Recovery was still in progress in 2004 when the tsunami caused further (although not quantitatively assessed ( [[#Gischler--2006|Gischler and Kikinger, 2006]] )) damage to the reef ecosystem. Post-1998 recovery ultimately took 15 years, (i.e., longer than following the 1987 ENSO event, after which recovery had only taken a few years) and also longer than in the neighbouring undisturbed Chagos atolls, thereby suggesting the alteration of the recovery capacity of the reef ecosystem by human-induced reef degradation and climate change ( [[#Morri--2015|Morri et al., 2015]] ; [[#Pisapia--2017|Pisapia et al., 2017]] ). Mid-2016, a new ENSO event occurred, which reduced living coral cover by 75% ( [[#Perry--2017|Perry and Morgan, 2017]] ). Future recovery of the reef ecosystem, which is critical to both current livelihoods and economic activities (especially diving-oriented tourism and fishing) and to long-term island persistence, will mainly depend first on the frequency and magnitude of future bleaching events, which are expected to increase due to ocean warming, and second on the highly variable effects of anthropogenic disturbances locally ( [[#Perry--2017|Perry and Morgan, 2017]] ; [[#Pisapia--2017|Pisapia et al., 2017]] ; [[#Duvat--2019b|Duvat and Magnan, 2019b]] ).

Additionally, the 2004 Indian Ocean tsunami ( [[#Magnan--2006|Magnan, 2006]] ) and the 2007 flood ( [[#Wadey--2017|Wadey et al., 2017]] ) caused damage totalling 62% of the country’s GDP ( [[#Luetz--2017|Luetz, 2017]] ). The tsunami also downgraded the Maldives (now a middle-income country) to the Least Developed Countries category and caused within-country migration, with 30,000 people (9.6% of the country’s population) displaced ( [[#Republic%20of%20Maldives--2009|Republic of Maldives, 2009]] ). These successive events, which had cumulative devastating effects on the reef ecosystem and cascading effects on health and well-being, livelihoods and the economy, highlighted the risk posed by limited recovery time to the whole social–ecological system as well as the detrimental effect of local human disturbances on reef recovery.

'''Cumulative Impacts of the 2017 Hurricanes in the Caribbean Region'''
Among the 29 Caribbean SIDS, 22 were affected by at least one Category 4 or 5 TC in 2017. These events highlighted how the pre-cyclone high exposure and vulnerability of these islands and their populations has caused a ‘cumulative community vulnerability’ ( [[#Lichtveld--2018|Lichtveld, 2018]] , p. 28) that has amplified the impacts of these TCs, which will in turn increase the long-term vulnerability of affected islands. The exposure of these islands over their entire surface, combined with the concentration of people, infrastructure, utilities and public services in flood-prone coastal areas, inadequate housing, limited access to healthy food and transportation, and unpreparedness explains widespread-to-total devastation ( [[#Shultz--2018|Shultz et al., 2018]] ; [[#Briones--2019|Briones et al., 2019]] ). The destruction of transport systems ( [[#Lopez-Candales--2018|Lopez-Candales et al., 2018]] ) and island supply chains ( [[#Kim--2019|Kim and Bui, 2019]] ), which heavily depend on ports, roads, power and communications, made rescue logistically complex, explaining the lack of freshwater, food supplies, medications and fuel on some islands for several weeks after the event. This cumulative vulnerability caused ‘cascading public health consequences’ ( [[#Shultz--2018|Shultz et al., 2018]] , p. 9), including delayed (i.e., over the next year) mortality, physical injury during the clean-up and recovery phase and increased risk of chronic, vector-borne, contaminated water-related diseases as well as of mental sequelae ( [[#Kishore--2018|Kishore et al., 2018]] ; [[#Ferre--2019|Ferre et al., 2019]] ).

The loss of mangroves ( [[#Branoff--2018|Branoff, 2018]] ; [[#Walcker--2019|Walcker et al., 2019]] ; [[#Taillie--2020|Taillie et al., 2020]] ) and terrestrial forests ( [[#Eppinga--2018|Eppinga and Pucko, 2018]] ; [[#Feng--2018|Feng et al., 2018]] ; [[#Hu--2018|Hu and Smith, 2018]] ; [[#Van%20Beusekom--2018|Van Beusekom et al., 2018]] ) exacerbated the cyclone-induced economic crisis. In the most affected islands, the destruction of buildings and outmigration generated a significant loss of tangible (e.g., museums) and intangible (e.g., traditional artistry) cultural heritage ( [[#Boger--2019|Boger et al., 2019]] ). Prolonged displacement of entire island populations (e.g., Ragged Island, the Bahamas, Barbuda) caused ‘non-economic loss and damage’, including threats to health and well-being, and loss of culture, sense of place and agency ( [[#Thomas--2019|Thomas and Benjamin, 2019]] ), which may further exacerbate the long-term vulnerability of concerned communities.

In early 2020, while island communities were still recovering from the 2017 hurricanes, the COVID-19 pandemic caused the closure of global transportation, with devastating socioeconomic impacts on tourism-dependent Caribbean economies ( [[#Sheller--2020|Sheller, 2020]] ), illustrating how compounding crises increase island vulnerability to both climate- and non-climate-related events.

<div id="box-15.2" class="h2-container box-container"></div>

'''Box 15.2 | Loss and Damage and Small Islands'''
<div id="h2-20-siblings" class="h2-siblings"></div>

Loss and damage has a range of conceptualisations ( [[IPCC:Wg2:Chapter:Chapter-1#1.4.4.2|Section 1.4.4.2]] ; Cross-Chapter Box LOSS in Chapter 17) and is a critical issue for many small islands, closely related to issues of climate justice ( [[#15.7|Section 15.7]] ). Small islands are already experiencing an array of negative climate change impacts while climate risks are projected to increase as global average temperatures rise (Sections 15.3, 16.2; Cross-Chapter Paper 2). Barriers and limits to adaptation also contribute to greater levels of both economic and non-economic loss and damage for small islands (Sections 15.6, 16.4).

For SIDS in particular, loss and damage has negative implications for sustainable development ( [[#Benjamin--2018|Benjamin et al., 2018]] ). The costs of loss and damage, particularly from extreme events, can deplete national capital reserves ( [[#Noy--2019|Noy and Edmonds, 2019]] ). [[#Thomas--2017|Thomas and Benjamin (2017)]] show how loss and damage can lead to an ‘unvirtuous cycle of climate-induced erosion of development and resilience’. In this cycle, addressing loss and damage strains limited national resources, diverting public funding and other resources to address negative climate impacts. This in turn reduces resources and capacities which could be allocated to adaptation, building resilience and sustainable development, thereby increasing vulnerability to climate change and leading to further loss and damage where the cycle begins again. The cascading and cumulative impacts of extreme events experienced in Pacific and Caribbean SIDS exemplify that this cycle may already be in effect.

In addition to the strain on national resources that loss and damage currently presents, credit ratings of SIDS have recently begun to include vulnerability to climate change, which may have negative impacts on their abilities to borrow external funds, attract foreign investment or access concessional financing ( [[#Buhr--2018|Buhr et al., 2018]] ; [[#Volz--2020|Volz et al., 2020]] ). Costs of addressing loss and damage may also affect the ability of SIDS to repay external debt, thus endangering eligibility for future access to funding ( [[#Baarsch--2016|Baarsch and Kelman, 2016]] ; [[#Klomp--2017|Klomp, 2017]] ; [[#Shutter--2020|Shutter, 2020]] ). These factors may place SIDS in situations where they face mounting costs of climate change with eroding capacities and resources to address loss and damage.

In the international policy arena, small islands—as part of the AOSIS—have been strong advocates for including loss and damage in the United Nations Framework Convention on Climate Change (UNFCCC); highlighting the increasing and irreversible risks that climate change poses for islands in particular ( [[#Roberts--2015|Roberts and Huq, 2015]] ; [[#Adelman--2016|Adelman, 2016]] ; [[#Mace--2016|Mace and Verheyen, 2016]] ). AOSIS, along with other developing countries and groups, have advocated that there is a pressing need for finance and resources to address loss and damage as well as greater integration of loss and damage in the UNFCCC and the Paris Agreement, including in capacity building, technology and the global stocktake ( [[#Benjamin--2018|Benjamin et al., 2018]] ; [[#Nand--2020|Nand and Bardsley, 2020]] ).

<div id="15.4" class="h1-container"></div>

<span id="detection-and-attribution-of-observed-impacts-of-climate-change-on-small-islands"></span>