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

== 15.2 Points of Departure from AR5 ==

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Points of departure from AR5 are highlighted in this section in relation to exposure, vulnerability, impacts and risks ( [[#15.2.1|Section 15.2.1]] ), and adaptation options ( [[#15.2.2|Section 15.2.2]] ).

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=== 15.2.1 Points of Departure on Exposure, Vulnerability, Impacts and Risks ===

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Scientific studies since AR5 confirm that global temperature will continue to increase even if greenhouse gas emissions are drastically reduced and will escalate the vulnerability, impacts and multiple interrelated risks experienced by small islands ( ''high confidence'' ) ( [[#IPCC--2018|IPCC, 2018]] ). A greater sense of urgency in lowering global greenhouse gas emissions and a call for action now is resonating among small island states.

Post-AR5 new studies confirm observed impacts on the natural and human systems and indicate projected risks in both these systems over time. Over the past four decades, there was a significant increase in the probability of the global exceedances of tropical cyclones (TCs) of major intensity ( [[#Kossin--2020|Kossin et al., 2020]] ), a trend confirmed by the occurrence of a growing number of intense TCs affecting the Atlantic and Pacific regions since AR5 ( [[#Magee--2016|Magee et al., 2016]] ; [[#Bhatia--2019|Bhatia et al., 2019]] ; [[#Knutson--2019|Knutson et al., 2019]] ). Also, scientific evidence since AR5 has confirmed that tropical corals are presently at high risk ( ''very high confidence'' ) and if global warming exceeds 1.5°C, known coral reef restoration options may be ineffective ( [[#IPCC--2018|IPCC, 2018]] ). Even achieving emission reduction targets consistent with the ambitious goal of 1.5°C of global warming under the Paris Agreement will result in the further loss of 70–90% of reef-building corals compared to today, with 99% of corals being lost under warming of 2°C or more above the pre-industrial period ( ''high confidence'' ) ( [[#Hoegh-Guldberg--2018|Hoegh-Guldberg et al., 2018]] ).

Additionally, since the last assessment, more robust scientific evidence exists on the impacts of sea level rise (SLR) and extreme sea level (ESL) events on small islands. Under Representative Concentration Pathways emission scenarios, RCP2.6, RCP4.5 and RCP8.5, many low-lying coastal areas at all latitudes, including small islands, will experience SLR and ESL events such as coastal storm surges and coastal flooding more frequently in the coming decades ( [[IPCC:Wg2:Chapter:Chapter-4#4.2.3|Section 4.2.3.4.1]] ; [[#IPCC--2019|IPCC, 2019]] ). SLR and ESL events will affect atoll islands and islands with higher elevations differently. New studies forecast that small islands are ''likely'' to experience some of the largest increases in endemic extinctions and may substantially contribute to future global biodiversity loss as well as to impaired ecosystem functioning ( [[#Fortini--2015|Fortini et al., 2015]] ; [[#Vogiatzakis--2016|Vogiatzakis et al., 2016]] ; [[#Cramer--2018|Cramer et al., 2018]] ). Scientific evidence points to large population reductions with an extinction risk of 100% for endemic species within insular biodiversity hotspots by 2100 ( [[#IPBES--2018|IPBES, 2018]] ; [[#Manes--2021|Manes et al., 2021]] ). An overarching concern since AR5 is the reduced habitability of small islands. Eight key risks (KRs) affecting the habitability of small islands are identified in this assessment and these are covered in the pertinent sections of this chapter which assess adaptation responses.

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=== 15.2.2 Points of Departure on Adaptation ===

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New knowledge of adaptation responses used in small islands has grown significantly since AR5. Strategies include hard protection, land reclamation and permanent relocation, with improved appreciation for when each strategy is relevant ( [[#IPCC--2019|IPCC, 2019]] ). Evidence of migration as an adaptation response to climate change remains limited ( [[#Roland--2020|Roland and Curtis, 2020]] ). Understanding of ecosystem-based adaptation (EbA) has improved considerably but there is ''medium agreement'' regarding its benefits ( [[#Doswald--2014|Doswald et al., 2014]] ; [[#Nalau--2018a|Nalau et al., 2018a]] ) and ''limited evidence and low agreement'' on its economic efficiency and long-term effectiveness ( [[#Renaud--2016|Renaud et al., 2016]] ; [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ).

Since the previous assessment, integration of IKLK into adaptation is recognised as a major benefit in preparing and recovering from TCs and EbA ( [[#Narayan--2020|Narayan et al., 2020]] ). The roles of social capital, health-related adaptation strategies and livelihood responses are more fully understood ( [[#Nalau--2018b|Nalau et al., 2018b]] ; [[#Nunn--2018|Nunn and Kumar, 2018]] ; [[#Abram--2019|Abram et al., 2019]] ; [[#IPCC--2019|IPCC, 2019]] ). Gender equity, climate justice, climate services, early warning systems and disaster risk reduction (DRR) ( [[#Vaughan--2014|Vaughan and Dessai, 2014]] ; [[#Newth--2018|Newth and Gunasekera, 2018]] ), which were data gaps in AR5, have received more treatment, especially in the context of small islands. Stronger evidence confirms that education and awareness-raising enhance household and community adaptation ( ''high confidence'' ).

Knowledge has improved on limits to adaptation, including projected timeframes of limits for hard protection ( ''high confidence'' ) and EbA ( ''medium confidence'' ) ( [[#IPCC--2019|IPCC, 2019]] ). There is also a better understanding that barriers and governance challenges vary by island and island groups ( ''high confidence'' ) and result in them having different adaptive capacities ( [[#IPCC--2019|IPCC, 2019]] ). A major barrier to adaptation is limited information on the feasibility, outcomes and sustainability of adaptation responses in small islands. Moreover, limited time series data on monitoring and evaluation make evaluating the feasibility of adaptation responses difficult.

Adaptation financing for small islands has increased since AR5 although leveraging finance is a constraint and remains complex ( [[#Robinson--2017|Robinson and Dornan, 2017]] ). Informal microfinancing has grown and risk transfer mechanisms are being explored although funding and access to insurance schemes are limited ( [[#Handmer--2019|Handmer and Nalau, 2019]] ; [[#Nunn--2019a|Nunn and Kumar, 2019a]] ; [[#Petzold--2019|Petzold and Magnan, 2019]] ). In small islands the methods and mechanisms to assess climate-induced losses and damages remain undeveloped ( ''medium confidence'' ) ( [[#Thomas--2017|Thomas and Benjamin, 2017]] ; [[#Handmer--2019|Handmer and Nalau, 2019]] ).

Many small islands have experienced economic shock arising from COVID-19 and have had to re-direct investment previously targeting sustainable development ( [[#Sheller--2020|Sheller, 2020]] ). Adaptation will be affected by economic contraction and indebtedness. Framing adaptation within climate resilient development pathways (CRDPs) that emphasize systems transition and are implemented at scale may bolster small islands’ resilience to multiple shocks such as COVID-19.

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