Editing IPCC:AR6/WGII/Chapter-12 (section)

== 12.7 Knowledge Gaps ==

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Data deficiencies and heterogeneity in quantity, quality and geographical bias in knowledge limit people’s understanding of climate change, evaluation of its impacts and the implementation of adaptation and mitigation measures ( [[#Harvey--2018|Harvey et al., 2018]] ) in CSA. The number of publications is not representative of the sensitivity to climate change and vulnerability contexts of different sub-regions and sectors. This lack of representation in the mainstream literature may lead to a bias and, therefore, an underestimation of the overall climate-related impact for some CSA sub-regions ( [[#Sietsma--2021|Sietsma et al., 2021]] ). The reason for the relatively few quantitative studies might be the complexities of socio-demographic and economic factors and the lack of long-term and reliable data in these areas ( [[#Harvey--2018|Harvey et al., 2018]] ), along with other social, economic and technical constraints.

Most studies that assess vulnerability to climate change do not yet follow the concept adopted since AR5, which isolates exposure as an external variable (WGII AR5 Figure SPM 1) ( [[#IPCC--2014|IPCC, 2014]] ), and many still use the A and B system of climate-change scenarios from AR4, because the adoption of the RCP models has been slow. There is still limited literature on severe risks and little specific and explicit consideration of risk drivers in the region. Moreover, limits to adaptation and the effectiveness of adaptation measures in CSA remain largely understudied.

Research on the interactions between climate change and socioeconomic processes is not extensive ( [[#Barnes--2013|Barnes et al., 2013]] ; [[#Leichenko--2019|Leichenko and O’Brien, 2019]] ; [[#Thomas--2019|Thomas et al., 2019]] ). There is limited understanding of the multi-level synergistic effects of climate change and other drivers, including economic development from the household to the country level ( [[#Wilbanks--2010|Wilbanks and Kates, 2010]] ; [[#Leichenko--2014|Leichenko and Silva, 2014]] ; [[#Tanner--2015a|Tanner et al., 2015a]] ; [[#Carey--2017|Carey et al., 2017]] ). In the region, this deficit is greater for sectors other than agriculture, water and food.

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=== 12.7.1 Knowledge Gaps in the Sub-regions ===

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The knowledge gaps in the eight sub-regions are quite heterogeneous. In CA, climate-change research is notably insufficient in all sectors included in this report, considering that climatic change, variability and extremes are impacting and will continue to severely impact this sub-region, and the vulnerability of the social and natural systems is high. Data deficiencies must be overcome as renewed research on climate change updates models, scenarios and projected impacts across sectors and levels (i.e., household to country). In NWS, there is a lack of studies on the relationships with increased fire events, and the impacts on the infrastructure of all kinds, on certain lowland, marine and coastal ecosystems and on ecosystem functioning and the provision of environmental services. Experimental studies are rare and most necessary to identify critical ecological thresholds to support decision-making processes, linking glacier retreat to its consequences on biodiversity and ecosystems, combined with different land use trajectories. Complex interactions with processes such as peace agreements in Colombia are yet to be investigated ( [[#Salazar--2018|Salazar et al., 2018]] ). In NSA, there remains a limited amount of peer-reviewed literature addressing the implications of climate change on Indigenous cultures and their livelihoods. In SAM, further data are needed on the vulnerability of traditional populations, impacts on water availability and soil degradation, risks to biodiversity and resilience of ecosystems in connection with climate change.

There is a knowledge gap about the likely impact of climate change on NES biodiversity, soil degradation and best adaptation measures. SES is the most urbanised sub-region of CSA, but there are severe knowledge deficits related to the design, implementation and evaluation of adaptation policy plans with respect to climate change. Forecasts related to risk prevention require new studies that address down-scaled climate-change models with concrete solutions to increase cities’ resilience. In SWS, there is a lack of long-term studies addressing climate-change impacts on terrestrial, freshwater and marine ecosystems, which is mainly due to the lack of integrated observational systems. There is a lack of studies projecting future impacts of climate change on the cryosphere, water resources, hazards, risks and disasters on natural and human systems. This is mainly due to the lack of systematic documentation, analysis and evaluation of adaptation strategies adopted, as well as their limitations and the lessons learned from maladaptation processes. There is scant evidence about transformational adaptation to climate change and system resilience. In SSA, there is a need for information related to the cities’ vulnerability to climate change and the impacts of the direct effects of future climate change on cities, energy infrastructure and health. Also, there is a knowledge gap about the financing of climate-change adaptation in SSA.

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=== 12.7.2 Knowledge Gaps by Sector ===

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==== 12.7.2.1 Terrestrial and Freshwater Ecosystems and their Services ====

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Advances in scientific knowledge on the risks of climate-change impacts and the vulnerability and resilience of ecosystems to climate change are needed ( [[#Bustamante--2020|Bustamante et al., 2020]] ). Persistent climate change in tropical rainforests requires deeper study and understanding, overall in connection with the role of nutrients, deep-water availability and biodiversity. Further research is needed to understand feedback to climate systems of large-scale changes in the land surface in SA biomes. The region has important freshwater Global 200 Ecoregions, including the Orinoco River and Flooded Forests, Upper Amazon River and streams, and Amazon River and Flooded Forests, which represent a priority for freshwater biodiversity conservation at a global scale ( [[#Manes--2021|Manes et al., 2021]] ) (Cross-Chapter Paper 1; Figure 12.8). There is, however, a clear knowledge gap on the impacts of climate change on freshwater biodiversity in the region (Section [https://www.ipcc.ch/chapter/12#CCP1.2.3 CCP1.2.3] ; [[#Manes--2021|Manes et al., 2021]] ). Lastly, more interdisciplinary research is needed regarding conservation strategies and stable financial resources focusing on adaptation of ecosystems in the region ( [[#Mistry--2016|Mistry et al., 2016]] ; [[#Gebara--2017|Gebara and Agrawal, 2017]] ; [[#Ruggiero--2019|Ruggiero et al., 2019]] ; [[#To--2019|To and Dressler, 2019]] ).

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==== 12.7.2.2 Ocean and Coastal Ecosystems and Their Service ====

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There is an important lack of knowledge about the state of health of the ocean and coastal ecosystems along CSA (i.e., social-ecological data integration, poor sampling efforts, lack of information about the value of ecosystem services, lack of information about ecosystems cover and distribution, lack of studies about climate-change perceptions and social concerns), including marine fisheries (i.e., landing statistics not available, lack of reliable information on the scope of resource extraction, among others). Poor or absent monitoring programmes (physical, environmental and biological variables) that feed alert and surveillance systems are lacking in CSA. There is a general absence of a continuous line of scientific research or adequate baseline information about the impacts of climate change, as well as continuous monitoring of the adaptation plans adopted in ocean and coastal ecosystems that limit the formulation of adequate conservation and management programmes. When studies are performed, inadequate access to data limits the analyses of the existing information, making difficult to detect climate-change trends and impacts and develop effective adaptation strategies.

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==== 12.7.2.3 Water ====

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As in other sectors and environmental systems, for the water sector there are important limitations in terms of monitoring and data collection. High-quality, long-term hydrological data are unevenly available for different sub-regions and limit the possibility of obtaining a deeper understanding of changes in river runoff and lake or groundwater changes. Groundwater data are particularly scarce. There are important gaps related to the projections of water resources for the future. Much of current knowledge on future changes in water resources and water scarcity and flood risks is based on information from global-scale studies because studies specific to this region are scarce. Several elements that are important for IWRM, such as water quality, water demand, privatisation and other economic dynamics, and nutrient, pollutant and sediment flux are poorly known currently due to missing data and insufficient efforts to monitor them.

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==== 12.7.2.4 Food, Fibre and Other Ecosystem Products ====

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Integrative evaluation on impacts on food security, including agricultural production, distribution and access, leading to adaptation strategies is limited within the region. Limited information regarding cost-benefit analyses of adaptation in the food production sector is available in the region. It is also important to obtain a better understanding of adaptation effects to avoid maladaptation and promote site-specific and dynamic adaptation options considering available technologies. Compiling and systematising existing scientific and local knowledge on the relationship between forests, land cover/use and hydrological services is a gap that must be filled from a broader perspective in the region, which could contribute to formulating recommendations and inform restoration practices and policies. The literature also highlights widespread gaps between farmers’ information needs and services that are routinely available. There is evidence that when climate information services are created with farmer input and targeted in a timely and inclusive manner, they are a positive determinant of adaptation through the adoption of more resilient farm-level practices. However, current assessments of the economic impacts of climate information services are scarce; hence, more such studies are needed.

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==== 12.7.2.5 Cities, Settlements and Infrastructure ====

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Despite the high level of urbanisation in the region, studies on urban adaptation initiatives are still underreported by municipalities, and several practical results have not yet been demonstrated ( [[#Araos--2016|Araos et al., 2016]] ). This issue is particularly relevant to medium-sized cities because most of the literature and data available on adaptation refer to the major capital cities. The potential of applying new resilient parameters in building and land use regulations for adaptation is underreported. The same can be said about the impact of housing improvement and slum upgrading on climate resilience, even when initiatives are focused on reducing environmental and climate risk. Also relevant in the region is a gap in research about NbS applied to urban area adaptation, as in the case of the urban forestry potential for adaptation ( [[#Barona--2020|Barona et al., 2020]] ). Even though the importance of urban ecological infrastructure in providing ecosystem services, such as flood control, is reasonably well documented, its practical application in urban planning in CSA remains limited ( [[#Romero-Duque--2020|Romero-Duque et al., 2020]] ). Added to this is the lack of monitoring data on adaptation initiatives in general and, in particular, on adaptation initiatives in water systems that have already been implemented and their effects on risk reduction. A lack of monitoring data contributes to the lack of information about maladaptation in urban areas and its consequences. Mobility and transport system adaptation options remained virtually entirely unexplored, while mitigation options receive significant attention.

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==== 12.7.2.6 Health and Well-being ====

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There is a growing body of evidence that climate variability and climate change (CVC) cause harm to human health in CSA. However, there is a lack of information about the current and future projected impacts of CVC events on overall illness and death in this region. It is challenging to attribute specific health outcomes to CVC in models and field experiments due to multiple factors, including the following:

* lack of long-term, high-quality health surveillance data
* multiple interacting infectious disease and chronic health issues
* mismatch in the spatial and temporal scales of CVC and health measurements
* complex climate and human system dynamics, including non-linear time lags
* limited longitudinal data on non-climate factors that influence health outcomes (e.g., public health interventions, migration of human populations, seasonal patterns in livelihoods).

The uncertainty inherent in predictive models also makes it challenging to expand current localised knowledge on the impacts of infectious diseases associated with CVC to other regions or future climate scenarios ( [[#UNEP--2018|UNEP, 2018]] ).

Improved risk assessments based on better models and empirical research are needed to bridge the knowledge gap and inform the design of adaptation strategies. A systematic multi-scalar analysis of the impact of CVC on human health is needed across distinct social-ecological contexts. Data collection systems need to be strengthened to accurately estimate the burden of mortality and morbidity from heat and extreme events. The data deficit is a common problem in functioning civil registration and vital statistics systems, including lack of information on causes of death ( [[#UNEP--2018|UNEP, 2018]] ). In addition, there is a lack of consensus on globally accepted and operational definitions for both climate-related extremes and exposures/outcomes.

For infectious disease (vector-borne and water-borne), the technology available to estimate current and future risk areas is often limited by human or financial resource constraints in developing countries. There is a geographical mismatch between the areas producing the technology and knowledge (in the global north) and the areas most affected by CVC (in the global south). User-friendly tools that bring together climate and health information—without the need for modelling or GIS expertise—are needed for health sector decision makers.

There is a lack of studies that assess the feasibility of health adaptation measures ( [[#12.5.10|Section 12.5.10]] ), thereby limiting the ability of decision makers to compare different health interventions and identify bottlenecks for implementation. The growing field of implementation science could help to address barriers to mainstreaming climate information in the health sector as an adaptation strategy.

Finally, there is an almost complete absence of studies that address relationships of climate change with well-being in CSA, broadly understood as including emotions and moods, satisfaction with life, sense of meaning and positive functioning, including the capacity for unimpaired cognitive functioning and economic productivity ( [[IPCC:Wg2:Chapter:Chapter-7#7.1.4|Section 7.1.4.1]] ).

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==== 12.7.2.7 Poverty, Livelihood and Sustainable Development ====

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Climate change is becoming a major obstacle to poverty reduction and overcoming poverty traps. There is a need to better understand how poor and vulnerable communities are affected and the more effective ways to prevent it. The large majority of the poor in the region are living in urban areas ( [[#UNDESA--2019|UNDESA, 2019]] ); extreme urban poverty is increasingly more relevant, including the needs and priorities of informal settlements and economies, but less studied within the interaction with climate change. There is little reporting of major adaptation options implemented by or for vulnerable and poor urban dwellers ( [[#Ryan--2019|Ryan and Bustos, 2019]] ; [[#Berrang-Ford--2021|Berrang-Ford et al., 2021]] ).

Adaptation options are being increasingly documented for poverty-related impacts, despite the fact that the uncertain context from climate impacts is not uniform across communities and the very local scale of the type of adaptation responses needed ( [[#Miranda%20Sara--2016|Miranda Sara et al., 2016]] ; [[#Rosenzweig--2018|Rosenzweig et al., 2018]] ; [[#Dodman--2019|Dodman et al., 2019]] ). There is a huge gap in understanding how the poor respond to climate change, what is needed to support them and the interconnections among development policies, poverty and risk reduction with climate-change actions ( [[#Ryan--2019|Ryan and Bustos, 2019]] ; [[#Satterthwaite--2020|Satterthwaite et al., 2020]] ).

The literature to assess the effectiveness of pro-poor or low-income adaptation options continues to be weak; a very small proportion shows results associated with adaptation efforts ( [[#Magrin--2014|Magrin et al., 2014]] ; [[#Berrang-Ford--2021|Berrang-Ford et al., 2021]] ). Without this kind of approach and in-depth understanding there is the risk that top-down climate-change adaptation options could reinforce poverty cycles and neglect cultural values, even eroding them ( [[#Bartlett--2016|Bartlett and Satterthwaite, 2016]] ; [[#Walshe--2016|Walshe and Argumedo, 2016]] ; [[#Allen--2017a|Allen et al., 2017a]] ; [[#Hallegatte--2018|Hallegatte et al., 2018]] ; [[#Kalikoski--2018|Kalikoski et al., 2018]] ; [[#UN-Habitat--2018|UN-Habitat, 2018]] ).

The impacts of climate change on vulnerable groups remain understudied. There are little or no climate data on the remote mountain regions of CSA as well as research measuring the vulnerability of smallholders living there, making it hard to assess the expected changes or the possible adaptation measures ( [[#Pons--2016|Pons et al., 2016]] ; [[#Donatti--2019|Donatti et al., 2019]] ).

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==== 12.7.2.8 Cross-Cutting Issues in the Human Dimension ====

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A significant number of studies address the impacts of climate change on the Amazon rainforest ( [[#Brienen--2015|Brienen et al., 2015]] ; [[#Doughty--2015|Doughty et al., 2015]] ; [[#Feldpausch--2016|Feldpausch et al., 2016]] ; [[#Rammig--2020|Rammig, 2020]] ; [[#Sullivan--2020|Sullivan et al., 2020]] ); however, assessment of the tangible and intangible impacts of climate change on Indigenous Peoples’ cultures and livelihoods in this forest need to be further advanced ( [[#Brondízio--2016|Brondízio et al., 2016]] ; [[#Hoegh-Guldberg--2018|Hoegh-Guldberg et al., 2018]] ).

Studies on the perception of climate change in rural and urban populations throughout the region have increased, but there is a lack of more specific research on the perception of specific groups, such as economic or political actors, that influence public institutions and policies at the local, regional and national levels.

While studies on climate-change gender-differentiated impacts have grown over the past 10 years in CSA, studies on how gender intersects with other dimensions such as race, ethnicity, age or rural/urban setting are still needed. This will help to further understand how gender inequalities are connected to broader power structures in society and, thus, to produce evidence on the importance of an intersectional approach to climate change.

Regarding the relation of social movements and climate-change adaptation, institutions and politics, two major issues stand out: youth movements for climate change and the resistances, mainly urban, to climate-change adaptation policies. Little connection is found in research concentrating on resistance to climate-change adaptation policies and their interaction with the politics of place. Conflictivity related to climate change is another understudied issue.

Although there are several case studies on migrations and displacements caused by strong and immediate climatic threats, such as hurricanes or floods, and on slow-onset impacts, such as droughts or temperature increase, there are gaps in the attribution or relative weight of climate change in these processes.

Still important to note is that synergies between mitigation, adaptation, risk reduction and sustainable development have not been jointly explored, which would better facilitate adaptation policy approaches.

There are critical knowledge gaps in the interlinkages between social and environmental dynamics that are important for climate-change adaptation, as in Andean forest landscapes. A salient knowledge gap in this thematic area is the need to characterise how multi-level and multi-actor governance systems can enable sustainable land management practices, including ecosystem restoration ( [[#Mathez-Stiefel--2017|Mathez-Stiefel et al., 2017]] ). More capacities are needed to increase the generation of relevant knowledge. Even small grant programmes can sustain research projects that target the linkages between knowledge and decision-making at multiple scales ( [[#Báez--2020|Báez et al., 2020]] ).

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