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

==== 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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