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

== 15.8 Research Gaps ==

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Despite intensive study, many knowledge gaps remain due to the complexity of biophysical and social interactions as well as the local and regional diversity of small islands. Research and data gaps exist in four areas: island-scale data availability; ecosystem services data; vulnerability and resilience, and adaptation (Table 15.8).

'''Table 15.8 |''' Research gaps in small islands.

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! Research gap

! Elaboration

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| rowspan="7"| Unavailability of adequately downscaled climate data

| There is a lack of oceanographic (e.g., tidal), meteorological, high-resolution topographic and bathymetric data, as well as future sea level and wave climate projections for most islands, which severely constrain modelling studies and therefore improved understanding of future coastal flooding, erosion, and rates of saline intrusion into aquifers ( [[#Giardino--2018|Giardino et al., 2018]] ; [[#Lal--2019|Lal and Datta, 2019]] )

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| There is a need for further developing context-specific numerical models, especially through the inclusion of sediment transport, production and delivery ( [[#Shope--2019|Shope and Storlazzi, 2019]] ), coastal and marine ecosystems’ responses ( [[#Beetham--2017|Beetham et al., 2017]] ), and various societal responses (e.g., engineering and ecosystem-based solutions ( [[#Giardino--2018|Giardino et al., 2018]] )) under different climate change and SLR scenarios

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| The complexity and specificities of small island environments and unavailability of robust baseline data considerably challenge modelling studies in small islands contexts, as reflected by the serious limitations of global modelling impact studies for these ( [[#Mentaschi--2018|Mentaschi et al., 2018]] ; [[#Vousdoukas--2020|Vousdoukas et al., 2020]] )

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| Data and model developments are therefore urgently needed to assess the future habitability or exploitability of the islands that are the most critical to small island countries and territories, and to help identify and promote appropriate (especially in technical terms) solutions

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| Adequately downscaled Regional Climate Model (RCM) data (sub-5 km 2 ) is also required to conduct modelling assessments for small island terrestrial ecosystems. This is particularly needed for islands with complex topography which could be important in providing much-needed climate refugia for the survival of narrow range species such as endemics ( [[#Balzan--2018|Balzan et al., 2018]] ). Such spatial data could be used to maximise the potential of islands to deliver critical ecosystem services ( [[#Katovai--2015|Katovai et al., 2015]] ; [[#Balzan--2018|Balzan et al., 2018]] )

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| Widely used WorldClim data may not be suitable when applied to the small island context (Box [https://www.ipcc.ch/chapter/15#CCP1.1 CCP1.1] ). Without such data, robust ecosystem-based adaptation strategies such as climate-smart PA planning and management under changing climate conditions cannot be developed

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| [[#Thomas--2017|Thomas and Benjamin (2017)]] highlighted the lack of data as an area of concern related to assessing loss and damage at 1.5°C. Understanding losses and damages also requires more detail on island-specific losses and damages accruing from anthropogenic climate change impacts. At the moment, such assessments are limited, and most of the small islands have not yet documented these factors in their national adaptation plans or policies ( [[#Handmer--2019|Handmer and Nalau, 2019]] ). There is a need for specific studies also on biophysical variables and species (e.g., impact of temperature rise on mangroves); long-term impacts of ocean acidification on species, including relationship to disease outbreaks, and changing breeding grounds of marine species and impacts on fisheries and marine-based livelihoods; incorporating biophysical feedback and interconnectivity of environments into models; and more detailed datasets (e.g., bathymetry, coastal assets) ( [[#World%20Bank--2016|World Bank, 2016]] ; [[#McField--2017|McField, 2017]] ; [[#Wilson--2017|Wilson, 2017]] )

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| rowspan="4"| Vulnerability and resilience

| There is need for new research that investigates the variability of vulnerability within and between islands and states, typologies of best practice ( [[#Oculi--2018|Oculi and Stephenson, 2018]] ), frequency of knowledge sharing among islands and regions ( [[#Foley--2018|Foley, 2018]] ), identification of regional framework mechanisms, and mapping the complex impact and hazard interactions at a regional scale ( [[#Duvat--2017b|Duvat et al., 2017b]] ; [[#Neef--2018|Neef et al., 2018]] ; [[#Scandurra--2018|Scandurra et al., 2018]] ; [[#Thiault--2018|Thiault et al., 2018]] ). Research needs to also examine resilience-building efforts within the four domains of islandness (boundedness, smallness, isolation, and littorality) to effectively capture subjective nuances associated with climate development efforts on islands ( [[#Kelman--2018|Kelman, 2018]] )

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| Research gaps in place-based assessments of social service bundles coupled with policy actions ( [[#Balzan--2018|Balzan et al., 2018]] ) highlight the need for new knowledge to strengthen communication, collaboration and networks between academia, donors, the private sector, community and government ( [[#Allahar--2016|Allahar and Brathwaite, 2016]] ; [[#Schipper--2016|Schipper et al., 2016]] ) so as to improve understanding of vulnerability and resilience in small islands

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| A paucity of research exists currently on the vulnerability of island ecosystem services to climate change ( [[#Balzan--2018|Balzan et al., 2018]] ). While there is rich scientific evidence on the pressures of habitat loss and degradation, impacts of natural hazards and invasive species, far less is known about the interactions of these factors with adaptive capacity and livelihood conditions on islands. In small island contexts, there is a specific need for assessing the effectiveness and cost of ecosystem- and community-based solutions where the latter have been implemented ( [[#Filho--2020|Filho et al., 2020]] ). The design of generic assessment methods and tools is required to allow for comparative analyses that will, in turn, provide useful guidance for the promotion of context-specific adaptation strategies ( [[#Blair--2018|Blair and Momtaz, 2018]] ). For many of the small islands, especially SIDS, the economic valuation of marine and coastal ecosystem services—coastal protection, fisheries, tourism—is of great importance, as well as the subsequent losses in these sectors and related livelihoods due to climate change impacts ( [[#Waite--2014|Waite et al., 2014]] ; [[#Schuhmann--2015|Schuhmann and Mahon, 2015]] ; [[#World%20Bank--2016|World Bank, 2016]] ; Layne, 2017; [[#Duijndam--2020|Duijndam et al., 2020]] ). There are few integrated modelling studies to inform future habitability of differentiated small island types and how these models can inform decision support processes for ridge to reef stewardship ( [[#Povak--2020|Povak et al., 2020]] ). Existing studies ( [[#Rasmussen--2018|Rasmussen et al., 2018]] ) have progressed knowledge since AR5, but island-specific analyses are required to robustly estimate the future ability of land to support life and livelihoods, taking into account multiple climate-drivers, future population exposure, and adaptation responses

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| More research is also needed in understanding how ecosystem benefits are modified under changing climate conditions and how these benefits can be quantified ( [[#Doswald--2014|Doswald et al., 2014]] ). For example, many small islands lack comprehensive (and disaggregated) data related to food security, which makes it challenging to attribute climate impacts on local food systems ( [[#Taylor--2019|Taylor et al., 2019]] ). Balzan et al. (2018) highlight the importance of quantifying the role of biodiversity in delivering key ecosystem services and demonstrate how such data could provide insights into the interrelatedness of island ecosystems and transboundary service benefits

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| rowspan="4"| Adaptation

| In the last decade or so, there has been a significant increase in climate-related financing for small island states. However, monitoring and tracking of funding and metrics to evaluate overall impact are lacking ( [[#Boyd--2017|Boyd et al., 2017]] ; [[#Mallin--2018|Mallin, 2018]] ). Research into adaptation costs could benefit from the inclusion of indirect effects of climate change such as psychological costs ( [[#Vincent--2014|Vincent and Cull, 2014]] ; [[#Gibson--2019|Gibson et al., 2019]] ) but to date this research is missing. Greater effort could also be placed on quantifying the relationship between adaptation costs and adverse events ( [[#Adelman--2016|Adelman, 2016]] ). There is also a need for overall land use planning guidelines in small coastal communities, including small islands ( [[#Major--2016|Major and Juhola, 2016]] ). The usefulness and utility of insurance mechanisms for building resilience to climate hazards require up-to-date information on assets at risk ( [[#Tietze--2018|Tietze and van Anrooy, 2018]] ) and further exploration of adaptation measures in small island contexts ( [[#Baarsch--2016|Baarsch and Kelman, 2016]] ). Additionally, the differences between theoretical adaptation practices and observed results from actual implementation, along with the integration of IKLK and external knowledge, are currently not well understood ( [[#Mercer--2014b|Mercer et al., 2014b]] ; [[#Kelman--2015b|Kelman, 2015b]] ; [[#Saint%20Ville--2015|Saint Ville et al., 2015]] ; [[#Robinson--2016|Robinson and Gilfillan, 2016]] ; [[#Robinson--2017b|Robinson, 2017b]] ). Documenting experience-based knowledge of adaptation projects and programme implementation could fill important data gaps. At the project design stage, the paucity of climate finance data is a barrier to accessing climate finance ( [[#Bhandary--2021|Bhandary et al., 2021]] )

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| Although studies examining the association between climate and weather extremes, events and conditions and mobility in small islands have increased since AR5 ( [[#Birk--2014|Birk and Rasmussen, 2014]] ; [[#Kelman--2015a|Kelman, 2015a]] ; [[#Connell--2016|Connell, 2016]] ; [[#Stojanov--2017|Stojanov et al., 2017]] ; [[#Barnett--2018|Barnett and McMichael, 2018]] ), few studies robustly examine the attribution of migration of small island populations, communities and individuals to anthropogenic climate change and other non-climate migration drivers. Biophysical, socioeconomic and in situ adaptation thresholds that force small island populations to migrate remain under-explored ( [[#Barnett--2017|Barnett, 2017]] ; [[#Handmer--2019|Handmer and Nalau, 2019]] ). The implications of forced and voluntary immobility ( [[#Allgood--2017|Allgood and McNamara, 2017]] ; [[#Farbotko--2018|Farbotko, 2018]] ; [[#Suliman--2019|Suliman et al., 2019]] ), the socioeconomic, health, psychological and cultural outcomes of climate migrants, and gender dimensions of climate migration all remain under-researched

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| Limits to adaptation is still a largely under-researched topic globally ( [[#Nalau--2018|Nalau and Filho, 2018]] ) and specifically in small island contexts, as are the linkages between adaptation limits, loss and damage and transformative adaptation ( [[#Thomas--2020|Thomas et al., 2020]] ). In terms of projected risks and adaptation responses, further work is needed to improve knowledge of commonalities, differences, successes, and failures of natural and human adaptation responses ( [[#Kuruppu--2015|Kuruppu and Willie, 2015]] ). One of the failings of the current literature on limits to adaptation revolves largely around the use of barriers for sector-specific or small-scale scenarios, which provides an understanding only for that particular scenario and does not identify common constraints ( [[#Kuruppu--2015|Kuruppu and Willie, 2015]] ). Research gaps on loss and damage include: how to assess the economic costs of loss and damage; mechanisms to develop robust policies in small island contexts; specific data on experienced loss and damage across socioeconomic groups and demographics; monitoring and tracking of slow-onset events ( [[#Thomas--2017|Thomas and Benjamin, 2017]] ; [[#Thomas--2020|Thomas et al., 2020]] ) and the non-economic aspects including sense of place, health and community cohesion ( [[#Thomas--2019|Thomas and Benjamin, 2019]] )

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| More studies are needed on the role that organisations (international, national and regional) play in adaptation efforts—their effectiveness at achieving desired outcomes, roles and accountability ( [[#Robinson--2016|Robinson and Gilfillan, 2016]] ; [[#Scobie--2016|Scobie, 2016]] ; [[#Mallin--2018|Mallin, 2018]] ). It is also important that the impacts of sociopolitical relations inter-state are researched ( [[#Belmar--2015|Belmar et al., 2015]] ) and more focus on climate justice ( [[#Baptiste--2019|Baptiste and Devonish, 2019]] ; [[#Moulton--2019|Moulton and Machado, 2019]] ; [[#Gahman--2020|Gahman and Thongs, 2020]] ) and gender is similarly needed ( [[#McLeod--2018|McLeod et al., 2018]] ). Given the high number of place-specific case studies in the adaptation literature, more reviews are needed that synthesise key lessons and principles of adaptations in small island contexts from this knowledge. Further research is also needed to capture the lessons from COVID-19 response in small islands and how these could enable more robust adaptation and climate resilient development transitions as has been suggested at a broader scale by [[#Schipper--2020|Schipper et al. (2020)]] . There is also little to no information on impacts upon terrestrial and freshwater biodiversity from the relocation of coastal human populations inland due to SLR

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