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

==== 12.5.5.3 Adaptation Options in Urban Design and Planning ====

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Both the shape and activities of a city have an impact on carbon emissions, adaptation and mitigation opportunities ( ''high confidence'' ) ( [[#Raven--2018|Raven et al., 2018]] ; [[#Satterthwaite--2018|Satterthwaite et al., 2018]] ). Combining urgent measures, strategic action ( [[#Chu--2017|Chu et al., 2017]] ) on long-term planning is central for transformative adaptation and avoiding maladaptation ( [[#Filho--2019|Filho et al., 2019]] ). Urban planning, considering climate risk assessments, and regulation (e.g., land use and building codes), including climate-adapted parameters, are central to coordinating and fostering private and public investments in adaptation, reducing risks related to features of the built environment (infrastructure and buildings) and the occupation of risk areas (e.g., threatened by floods and landslides) ( [[#Rosenzweig--2018|Rosenzweig et al., 2018]] ). A lack of information at the local scale, human resources and clear liability for climate-change response planning can limit adaptation ( [[#Aylett--2015|Aylett, 2015]] ).

Strategic adaptation approaches have been adopted by many cities in dealing with the multi-level and intersectoral complexity of urban systems, with gains in fostering leadership and facing the predominant pattern of uneven urban development in the region ( ''medium confidence: limited evidence, high agreement'' ) ( [[#Chu--2017|Chu et al., 2017]] ). Medellin’s metropolitan green belt, for example, focuses on problems such as irregular settlements, inequality and poor governance, formulating programmes and projects of the municipality of Medellin and the municipalities of the Vale do Aburra in a strategic long-term plan. Places with informal and precarious settlements were slated to be transformed with the belt’s integration areas: eco-parks and eco-gardens ( [[#Alcaldía%20de%20Medellín--2012|Alcaldía de Medellín, 2012]] ; [[#Chu--2017|Chu et al., 2017]] ).

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===== 12.5.5.3.1 Housing, Informality and Risk Areas =====

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Informality and precariousness in housing is one of the most sensitive issues for adaptation in CSA cities ( ''medium confidence: medium evidence, high agreement'' ) ( [[#Satterthwaite--2018|Satterthwaite et al., 2018]] ; [[#UN-Habitat--2018|UN-Habitat, 2018]] ). Housing deficit in 2009, as a regional baseline, estimated that 37% of households suffered from quantitative or qualitative deficiencies due to the high cost of housing and the incidence of poverty ( [[#Blanco%20Blanco--2014|Blanco Blanco et al., 2014]] ; [[#McTarnaghan--2016|McTarnaghan et al., 2016]] ; NU CEPAL et al., 2016; [[#Vargas--2018a|Vargas et al., 2018a]] ; [[#Rojas--2019|Rojas, 2019]] ).

Policies and programmes have been implemented accumulating good practices and reducing the percentage of population in informal and precarious settlements (33.7% in 1990 to 21% in 2014) (NU CEPAL et al., 2016; [[#Satterthwaite--2018|Satterthwaite et al., 2018]] ; [[#Teferi--2018|Teferi and Newman, 2018]] ; [[#UN-Habitat--2018|UN-Habitat, 2018]] ). Slum upgrading and built-environment interventions (housing and infrastructure improvement and provision) in informal settlements can enhance adaptation ( ''high confidence'' ) ( [[#Teferi--2018|Teferi and Newman, 2018]] ; [[#Núñez%20Collado--2020|Núñez Collado and Wang, 2020]] ; [[#Satterthwaite--2020|Satterthwaite et al., 2020]] ) while reducing floods, landslides and cascading impacts of storms, floods and epidemics, as observed with the ‘incremental housing approach’ in Quinta Monroy ( [[#Rojas--2019|Rojas, 2019]] ) and the ‘social urbanism’ in Medellin ( [[#Garcia%20Ferrari--2018|Garcia Ferrari et al., 2018]] ).

The climate adaptation plans of several large CSA cities include efficient land use and occupation planning and urban control systems (comprising regulation, monitoring), fostering the articulation with housing and environmental policy (by means of intersectoral and multi-level governance), inhibiting and reducing the occupation of risk areas (mainly flooding and landslides risks); increasing population density in areas already served by infrastructure; expanding slum urbanisation and technical assistance programmes to improve and expand social housing ( ''high confidence'' ) ( [[#Municipio%20del%20Distrito%20Metropolitano%20de%20Quito--2020|Municipio del Distrito Metropolitano de Quito, 2020]] ; [[#Prefeitura%20Municipal%20do%20Salvador--2020|Prefeitura Municipal do Salvador, 2020]] ; [[#Municipalidad%20de%20Lima--2021|Municipalidad de Lima, 2021]] ; [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2021|Prefeitura da Cidade do Rio de Janeiro, 2021]] ; [[#Prefeitura%20do%20Município%20de%20São%20Paulo--2021|Prefeitura do Município de São Paulo, 2021]] ).

Housing programmes and initiatives that consider resilient construction and site selection strategies are still in their nascent stages ( [[#Martin--2013|Martin et al., 2013]] ). Initiatives in slum upgrading, social housing improvement and regularising land tenure, associated with infrastructure provision, do not usually focus on adaptation, although they often focus on risk reduction. Those initiatives, associated with a housing policy that guarantees access to land and decent housing, represent a comprehensive intervention in vulnerable neighbourhoods for their adaptation to climate change, and CbA (community-based adaptation) strategies, including housing self-management and the participation of cooperatives, demonstrate the need and opportunity to transition to a transformative urban agenda that encompasses sustainable development, poverty reduction, disaster-risk reduction, climate-change adaptation and climate-change mitigation ( ''high confidence'' ) ( [[#Muntó--2018|Muntó, 2018]] ; [[#UN-Habitat--2018|UN-Habitat, 2018]] ; [[#Valadares--2018|Valadares and Cunha, 2018]] ; [[#Bárcena--2020b|Bárcena et al., 2020b]] ; [[#Núñez%20Collado--2020|Núñez Collado and Wang, 2020]] ; [[#Satterthwaite--2020|Satterthwaite et al., 2020]] ).

Several large cities are implementing municipal risk management plans and management and restoration plans for hydrologically relevant areas, considering threats of drought and heat waves, integrated watershed management and flood control programmes ( ''high confidence'' ) ( [[#Municipio%20del%20Distrito%20Metropolitano%20de%20Quito--2020|Municipio del Distrito Metropolitano de Quito, 2020]] ; [[#Prefeitura%20Municipal%20do%20Salvador--2020|Prefeitura Municipal do Salvador, 2020]] ; [[#Municipalidad%20de%20Lima--2021|Municipalidad de Lima, 2021]] ; [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2021|Prefeitura da Cidade do Rio de Janeiro, 2021]] ; [[#Prefeitura%20do%20Município%20de%20São%20Paulo--2021|Prefeitura do Município de São Paulo, 2021]] ). Quito and Rio de Janeiro are two examples of comprehensive and effective city-level climate action that includes creating environmental protected areas, managing appropriate land use, household relocation and EWSs in areas vulnerable to high levels of precipitation associated with EbA, such as reforestation projects, to address natural hazards ( [[#ELLA--2013|ELLA, 2013]] ; [[#Anguelovski--2014|Anguelovski et al., 2014]] ; [[#Calvello--2015|Calvello et al., 2015]] ; [[#Alcaldía%20de%20Quito--2017|Alcaldía de Quito, 2017]] ; [[#Sandholz--2018|Sandholz et al., 2018]] ; [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2021|Prefeitura da Cidade do Rio de Janeiro, 2021]] ) ( [[#12.6.1|Section 12.6.1]] ). EWS and the use of mapping tools as undertaken in La Paz proved to be an effective adaptation measure in the face of increasing hydro-climatic extreme events ( [[#Aparicio-Effen--2018|Aparicio-Effen et al., 2018]] ).

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===== 12.5.5.3.2 Green and Grey Infrastructure =====

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Hybrid solutions, combining green and grey infrastructure (GGI), have been adopted for better efficiency in flood control ( [[#Ahmed--2019|Ahmed et al., 2019]] ; [[#Drosou--2019|Drosou et al., 2019]] ; [[#Romero-Duque--2020|Romero-Duque et al., 2020]] ), sanitation, water scarcity, landslide prevention and coastal protection ( ''high confidence'' ) ( [[#12.5.6.4|Section 12.5.6.4]] ; [[#Mangone--2016|Mangone, 2016]] ; [[#Depietri--2017|Depietri and McPhearson, 2017]] ; [[#Leal%20Filho--2018|Leal Filho et al., 2018]] ; [[#McPhearson--2018|McPhearson et al., 2018]] ). The adoption of NbS, which embraces well-known approaches such as GI and EbA ( [[#Pauleit--2017|Pauleit et al., 2017]] ; [[#Le--2020|Le, 2020]] ), has increased (Box 1.3). The Fund for the Protection of Water (FONAG) and the Participative Urban Agriculture (AGRUPAR) are initiatives using NbS in Quito ( [[#12.6.1|Section 12.6.1]] ). An example of GGI is a stormwater detention pond as a water storage solution to flood prevention, allowing multiple uses of an urban space, and adapting and revitalising a degraded area in Mesquita, Rio’s metropolitan region ( [[#Jacob--2019|Jacob et al., 2019]] ). These systemic and holistic solutions still need to overcome governance and sectorial barriers to be more widely adopted ( [[#Herzog--2019|Herzog and Rozado, 2019]] ; [[#Wamsler--2020|Wamsler et al., 2020]] ; [[#Valente%20de%20Macedo--2021|Valente de Macedo et al., 2021]] ).

Managing water in cities in an adaptive way has been central to reducing impacts such as floods and contributes to water security ( ''high confidence'' ) ( [[#Van%20Leeuwen--2016|Van Leeuwen et al., 2016]] ; [[#Okumura--2021|Okumura et al., 2021]] ). Many cities facing frequent heavy storms that impact mostly underprivileged communities, slums and vulnerable areas could benefit from integrated NbS for disaster risk reduction and adaptation ( ''high confidence'' ) ( [[#Sandholz--2018|Sandholz et al., 2018]] ; [[#Ronchi--2019|Ronchi and Arcidiacono, 2019]] ). A study covering 70 Latin American cities estimated that 96 million people would benefit from improving main watersheds with GI ( [[#Tellman--2018|Tellman et al., 2018]] ). In several municipal climate plans, NbSs were introduced mainly to enhance rainwater management, reduce energy consumption and urban heat areas, improve water quality, prevent landslides and set aside green areas ( ''high confidence'' ) ( [[#Gobierno%20de%20la%20Ciudad%20de%20Buenos%20Aires--2015|Gobierno de la Ciudad de Buenos Aires, 2015]] ; [[#Municipio%20del%20Distrito%20Metropolitano%20de%20Quito--2020|Municipio del Distrito Metropolitano de Quito, 2020]] ; [[#Prefeitura%20Municipal%20de%20Curitiba--2020|Prefeitura Municipal de Curitiba, 2020]] ; [[#Alcaldía%20de%20Medellín--2021|Alcaldía de Medellín, 2021]] ; [[#Municipalidad%20de%20Lima--2021|Municipalidad de Lima, 2021]] ; [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2021|Prefeitura da Cidade do Rio de Janeiro, 2021]] ; [[#Prefeitura%20do%20Município%20de%20São%20Paulo--2021|Prefeitura do Município de São Paulo, 2021]] ). São Paulo’s project for Jaguaré River proposes a large-scale landscape transformation applying innovative multi-functional NbSs instead of exclusively large, expensive and monofunctional hard-engineered solutions to manage stormwater ( [[#Marques--2018|Marques et al., 2018]] ; [[#Herzog--2019|Herzog and Rozado, 2019]] ). In Bogota, the Humedales Foundation has restored wetlands to enhance areas near the Van Der Hammen reserve to improve water quality and quantity, restore habitat for biodiversity and provide flood protection ( [[#Portugal%20Del%20Pino--2020|Portugal Del Pino et al., 2020]] ). In Petrópolis, a medium-sized city in the hills of Rio de Janeiro state, the water service company has implemented 10 NbS multi-functional micro wastewater treatment plants in low-income areas, helping to reduce cascading impacts of storms, floods and epidemics ( [[#Herzog--2019|Herzog and Rozado, 2019]] ). In Costanera Sur, Buenos Aires, a public initiative to protect an auto-regenerated River Plate bank, which had received demolition material to create land, currently offers numerous ecosystem services for residents and attract visitors, activating the tourist industry and helping reducing riverine floods ( [[#Bertonatti--2021|Bertonatti, 2021]] ; [[#OICS--2021|OICS, 2021]] ).

A hybrid solution to water management that merges traditional interventions in urban areas with sustainable urban drainage systems (SUDSs) ( [[#Davis--2017|Davis and Naumann, 2017]] ), considering small-scale low-impact development (LID) measures scattered over the watershed instead of concentrate huge hydraulic grey structures, can help reduce the risk and damage of flooding ( ''high confidence'' ) ( [[#Miguez--2014|Miguez et al., 2014]] , 2015a; [[#Depietri--2017|Depietri and McPhearson, 2017]] ; [[#Da%20Silva--2018a|Da Silva et al., 2018a]] ; [[#de%20Macedo--2018|de Macedo et al., 2018]] ). Quito’s climate plan explicitly cites the strategy for implementing blue and grey infrastructure to reduce risk due to extreme precipitation and its associated impacts such as flooding and landslides and the possible impact of water scarcity ( [[#Municipio%20del%20Distrito%20Metropolitano%20de%20Quito--2020|Municipio del Distrito Metropolitano de Quito, 2020]] ). The Integrated Iguaçu-Sarapuí River Basin Flood Control Master Plan, in Rio’s metropolitan area, combines different solutions to flood protection, focusing on river restoration by retrofitting levee systems combined with adapting land use to provide a multi-functional landscape as an alternative to bring together green and grey solutions, creating urban parks to prevent further paving and avoid irregular occupation of riverbanks and provide storage capacity for damping flood peaks ( [[#Miguez--2015b|Miguez et al., 2015b]] ).

Many cities are implementing adaptation measures on integrated water and flood management systems ( [[#Sarkodie--2019|Sarkodie and Strezov, 2019]] ), improving basic sanitation services ( ''medium confidence: medium evidence, high agreement'' ). The main strategies are established by NAPs periodically focusing on improving water distribution network and reservoir systems, as in Honduras ( [[#Government%20of%20Honduras--2018|Government of Honduras, 2018]] ) and Ecuador ( [[#Mills-Novoa--2020|Mills-Novoa et al., 2020]] ), sewage and effluent treatment, as in Guatemala, Brazil and Paraguay ( [[#Government%20of%20Brazil--2007|Government of Brazil, 2007]] ; [[#Government%20of%20Guatemala--2016|Government of Guatemala, 2016]] ; [[#Government%20of%20Paraguay--2017|Government of Paraguay, 2017]] ), facing water scarcity and environmental degradation. Local authorities follow this guideline in an effort to maintain and upgrade existing drainage systems in Georgetown ( [[#Mycoo--2014|Mycoo, 2014]] ) or in Medellin, focusing on improving drainage systems to prevent landslides or flooding ( [[#Núñez%20Collado--2020|Núñez Collado and Wang, 2020]] ; [[#Alcaldía%20de%20Medellín--2021|Alcaldía de Medellín, 2021]] ). Rio de Janeiro has constructed three large stormwater detention reservoirs to deal with frequent flood, ( [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2015|Prefeitura da Cidade do Rio de Janeiro, 2015]] ), adopting a set of exclusively grey solutions, not combined into a NbS that could improve urban flood resilience ( [[#Rezende--2019|Rezende et al., 2019]] ). The main proposed actions still consider the traditional approach in improving the hydraulic capacity of urban drainage systems as an adaptive measure ( ''high confidence'' ) (Gobierno de la Ciudad de Buenos Aires, 2020; [[#Prefeitura%20Municipal%20do%20Salvador--2020|Prefeitura Municipal do Salvador, 2020]] ; [[#Municipalidad%20de%20Lima--2021|Municipalidad de Lima, 2021]] ; [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2021|Prefeitura da Cidade do Rio de Janeiro, 2021]] ). In addition to this strategy, several local plans propose actions for the retention and storage of rainwater, both in urban drainage networks on a smaller intervention scale ( [[#Prefeitura%20Municipal%20de%20Curitiba--2020|Prefeitura Municipal de Curitiba, 2020]] ) and along rivers and canals with large-scale works ( ''medium confidence: medium evidence, high agreement'' ) (Gobierno de la Ciudad de Buenos Aires, 2020; [[#Prefeitura%20Municipal%20de%20Curitiba--2020|Prefeitura Municipal de Curitiba, 2020]] ; [[#Alcaldía%20de%20Medellín--2021|Alcaldía de Medellín, 2021]] ; [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2021|Prefeitura da Cidade do Rio de Janeiro, 2021]] ).

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===== 12.5.5.3.3 Mobility and Transport System =====

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Mobility and transport systems play a key role in urban resilience ( ''high confidence'' ) ( [[#Walker--2014a|Walker et al., 2014a]] ; [[#Caprì--2016|Caprì et al., 2016]] ; [[#Espinet--2016|Espinet et al., 2016]] ; [[#Lee--2016|Lee and Lee, 2016]] ; [[#Ford--2018|Ford et al., 2018]] ; [[#Mehrotra--2018|Mehrotra et al., 2018]] ; [[#Quinn--2018|Quinn et al., 2018]] ). Examples reported in the scientific literature assessed focus on mitigation strategies, even when they are labelled as adaptation measures ( [[#da%20Silva--2016|da Silva and Buendía, 2016]] ; [[#Di%20Giulio--2018|Di Giulio et al., 2018]] ; [[#Valderrama--2019|Valderrama et al., 2019]] ; [[#Goes--2020|Goes et al., 2020]] ).

The integration of transport and land use planning and the improvement of public transport, also as important mitigation actions, has emerged as a consensus in countries’ adaptation plans; nevertheless, emphasis on mobility and transport systems in the many published NAPs is low ( ''medium confidence: medium evidence, high agreement'' ). The NAPs of Honduras, Costa Rica and El Salvador do not approach adaptation or mitigation in the sector, while those of Peru, Ecuador, Guatemala and Paraguay focus on mitigation only. The NAPs of Chile, Colombia and Brazil focus on both mitigation and adaptation of mobility and transport systems. Chile’s and Colombia’s plans dedicate specific action lines to adapting mobility and transport systems to climate change, while Brazil published a complementary volume to accompany its NAP that is dedicated exclusively to sectoral strategies, although it presents only general guidelines ( [[#Government%20of%20Peru--2010|Government of Peru, 2010]] ; [[#Government%20of%20Chile--2014|Government of Chile, 2014]] ; [[#Government%20of%20Ecuador--2015|Government of Ecuador, 2015]] ; [[#Government%20of%20Brazil--2016|Government of Brazil, 2016]] ; [[#Government%20of%20Colombia--2016|Government of Colombia, 2016]] ; [[#Government%20of%20Guatemala--2016|Government of Guatemala, 2016]] ; [[#Government%20of%20Paraguay--2017|Government of Paraguay, 2017]] ; [[#Government%20of%20Costa%20Rica--2018|Government of Costa Rica, 2018]] ; [[#Government%20of%20Honduras--2018|Government of Honduras, 2018]] ; [[#Government%20of%20El%20Salvador--2019|Government of El Salvador, 2019]] ).

On the municipal scale, among the biggest cities, São Paulo, Rio de Janeiro, Lima and Santiago stand out for including mobility and transport as a strategic axis of its climatic plans, though they prioritise mitigation, while Buenos Aires and Bogota do not delve into the issue in their plans ( [[#Gobierno%20de%20la%20Ciudad%20de%20Buenos%20Aires--2015|Gobierno de la Ciudad de Buenos Aires, 2015]] ; [[#Prefeitura%20da%20Cidade%20do%20Rio%20de%20Janeiro--2016|Prefeitura da Cidade do Rio de Janeiro, 2016]] ; [[#Alcaldía%20Mayor%20de%20Bogotá%20D.C.--2018|Alcaldía Mayor de Bogotá D.C., 2018]] ; [[#Municipalidad%20de%20Lima--2021|Municipalidad de Lima, 2021]] ; [[#Municipalidad%20de%20Santiago--2021|Municipalidad de Santiago, 2021]] ; [[#Prefeitura%20do%20Município%20de%20São%20Paulo--2021|Prefeitura do Município de São Paulo, 2021]] ). Most of those same cities have sectoral mobility plans, which are key tools in urban resilience. Those plans, however, do not focus on adaptation actions, instead emphasising mitigation ( [[#Government%20of%20Peru--2005|Government of Peru, 2005]] ; [[#Gobierno%20de%20la%20Ciudad%20de%20Buenos%20Aires--2011|Gobierno de la Ciudad de Buenos Aires, 2011]] ; [[#Prefeitura%20do%20Município%20de%20São%20Paulo--2015|Prefeitura do Município de São Paulo, 2015]] ; [[#Alcaldía%20Mayor%20de%20Bogotá%20D.C.--2017|Alcaldía Mayor de Bogotá D.C., 2017]] ; [[#Ilustre%20Municipalidad%20de%20Santiago--2019|Ilustre Municipalidad de Santiago, 2019]] ; [[#Município%20de%20Rio%20de%20Janeiro--2019|Município de Rio de Janeiro, 2019]] ).

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