Pamela Smith, Eugenia Gayó, Estela Blanco, Pablo Sarricolea, Karla Yohannessen, Anahí Urquiza, Marco Billi, CR2 researchers, and Teresita Alcántara, School of Government and Public Transformation, Tecnológico de Monterrey, Mexico
Edited by: José Barraza, CR2 Science Disseminator
- The urban climate is characterized by the existence of heat islands, which implies that cities generally have a higher temperature relative to their rural surroundings.
- In Chile, it has been verified that different temperatures exist within the same city. In summer, both daytime and nighttime temperatures are lower in higher-income neighborhoods and higher in lower-income neighborhoods.
- The country lacks a legal framework that guarantees high-quality urban climates for the population.
The 21st century marks a turning point both in terms of accelerated urban expansion and the increasingly evident impacts of climate change on our cities. At this intersection, attention – and concerns – about how changing climatic conditions behave and manifest within cities are beginning to take on increasing prominence.
Latin America is one of the most urbanized regions on the planet, with about 80% of its population living in cities. This phenomenon is even more evident in Chile, as the urban population reaches 88% (INE, 2017). It is known that urban growth modifies natural and semi-natural land covers, replacing them with artificial land uses and covers that alter energy balances and, therefore, generate different climatic conditions. This phenomenon is called urban climate, which is defined by modifications of the original conditions of temperature, air humidity, pollution, and albedo, among others.
Usually, the urban climate is characterized by the existence of heat islands, which imply that the city has a higher air temperature compared to its rural surroundings, which undoubtedly has effects, for example, on population health, thermal comfort, or energy demand for air conditioning [1].
Additionally, under climate change scenarios, it is anticipated that temperature extremes will intensify in the future, thus increasing the frequency of heat waves or nocturnal heat. These extreme temperature events interact with heat islands, increasing their intensity and duration. According to future projections (2035-2065) available on the ARClim platform, the occurrence of such extreme events and the urban heat island (UHI) would increase in all cities, especially in the northern and central zones of the country. This is concerning, as heat exposure can cause heat exhaustion or sunstroke and produce or exacerbate health conditions (e.g., headaches, dizziness) and aggravate existing chronic diseases, mainly due to the cardiovascular response to heat and dehydration.
Scientific evidence indicates that urban climate behavior is related to and depends on city design and planning at different scales, such as the percentage of soil sealing, the percentage of vegetation cover, colors and types of construction materials, or building heights (Smith & Romero, 2016). Because urban morphology, green areas, and other parameters vary across the city, temperature also varies, with variations occurring at the neighborhood and block scale. Consequently, inequity arises regarding the degree to which different population groups are exposed to these climatic hazards. Work conducted by the CR2 Resilient Cities Line further indicates that these inequities are compounded by other social and economic conditions of inequality specific to each neighborhood (Sarricolea et al., 2022). For example, it has been verified that in different larger, medium-sized Chilean cities, the average summer surface temperature during the day and night is lower (lesser heat island) in neighborhoods with higher economic incomes (ABC1 and C2). The opposite occurs in neighborhoods with lower socioeconomic levels, regardless of latitude and position relative to the sea, city size, and number of inhabitants (Figure 1).
Figure 1. Relationship between summer daytime surface temperature (in °C) and the socioeconomic level of each analyzed block in the cities of Arica (left) and Coyhaique (right). Note: In the graph, red points represent extreme values of variance.
As an example of temperature differences within a city, Figure 2 shows the differences between the maximum temperatures reached and the number of heat wave episodes among official meteorological stations (SINCA and Meteochile network) located in different areas of the same city during an extremely hot summer. The differences between the two communes of Santiago city, Las Condes and Independencia, stand out, with one and six heat wave episodes, respectively, which could be explained because they represent very different environmental and urban conditions. Las Condes generally has lower construction densities and more vegetation cover, with trees and grass, which cools surfaces and provides shade.
Figure 2. Spatial differences in heat waves recorded in Santiago, summer 2015-2016. The column “T° above threshold” corresponds to the days when the maximum temperature exceeds the 90th percentile, as defined by the Chilean Meteorological Directorate. The “T°” column represents the maximum temperature reached during the period, from highest (red) to lowest (blue). Note: It should be noted that the Puente Alto and Parque O’Higgins stations are in vegetated areas; therefore, they do not adequately represent the urban conditions of their surroundings
In contrast, Independencia, a commune with a lower socioeconomic level than Las Condes, is characterized by higher construction density and less green space. This implies that the poorest neighborhoods in cities are more exposed to high temperatures. At the same time, people with a lower socioeconomic level have more significant difficulties in reducing the intensity of the urban heat island due to a lack of access to technological resources (e.g., air conditioning or housing with better thermal insulation) or potable water, which could allow them to maintain adequate thermal comfort conditions both outside and inside their homes. In this way, the inequitable distribution of heat islands (an urban design problem) combines with the inequitable distribution of income and poverty (a social justice problem) and radicalizes the vulnerability of the poorest populations. This forces us to reflect more deeply on the issues of climate injustice linked to extreme heat and urban planning.
Climate justice has garnered increasing interest in recent years associated with climate change, making visible recurrent inequity in the distribution of benefits and impacts (Schlosberg, 2013). On a global scale, this has led to questions such as whether and how there should be compensation from those countries and populations that have emitted or emit more greenhouse gases to those that have emitted less, but which today – or in the future – will suffer more markedly from the impacts of climate change, affecting their ways and quality of life (Williges et al., 2022). Despite the importance of justice and the effects of climate change in cities, they have yet to be considered in urban studies (Bulkeley et al., 2013), especially in our country.
Urban Planning and Climate
Although some Chilean cities are regulated by urban and environmental norms and standards (air quality, noise, etc.), in general, until now there has not been a legal framework in the country that guarantees high-quality urban climates for the population (Alcoforado et al., 2009). This lack of institutionalization could be explained, in part, by budgetary constraints, conflicts of interest, lack of political will, lack of adequate meteorological data, and short-term priority setting and planning.
Communal Regulatory Plans (PRC) in Chile are territorial planning instruments that define, among other things, occupancy density criteria, maximum building heights, buildability coefficients, and other urban parameters that can affect the urban microclimate and, in turn, the comfort of public spaces. However, climate behavior is not considered a factor contributing to decision-making. If what is declared in the PRCs is compared with current characteristics, the wide margin that many sectors in Chilean cities still must increase density and height is evident, which can mean a decrease in visible sky or sky openness, causing effects on direct solar radiation, and access to sun and shade within a street.
The documents and reports prepared in the country concerning adaptation and mitigation to climate change have meant the progressive installation of the climate factor in decision-making. For example, it can be mentioned that an essential part of the strategies presented in the “Adaptation Plan for Climate Change in Cities” (MMA, 2018) require implementation through local governments. Furthermore, with the enactment of the Framework Law on Climate Change (LMCC; Law 21,455, 2022), an obligation was generated for all communes to address the climate crisis with greater ambition to achieve resilience and carbon neutrality by 2050 at the latest through the development of Communal Climate Change Action Plans (Article 12, LMCC), in which they must indicate appropriate measures to address the climate risks faced by cities and their inhabitants, including UHIs and heat waves.
It should be noted that the LMCC establishes (in its Article 2, letter d) “Equity and Climate Justice” as one of its fundamental guiding principles, stating in this regard that “it is the duty of the State to ensure a fair allocation of burdens, costs, and benefits, safeguarding the capacity of future generations to meet their own needs, with a gender approach and special emphasis on sectors, territories, communities, and ecosystems vulnerable to climate change. Climate justice seeks fair treatment for all people, as well as avoiding discrimination that may be entailed by certain policies and decisions intended to address climate change.” This makes it necessary to incorporate, both in local climate planning instruments and in territorial planning, heat islands, extreme climate events, and their correlation with other forms of territorial inequality as crucial dimensions for diagnosis and action, identifying vulnerable groups to promote territorial justice and equity.
Additionally, municipalities in Chile have different environmental and climate management instruments or initiatives, three of which are voluntary: 1. The Municipal Environmental Certification System (SCAM) of the Ministry of Environment, whose highest level corresponds to Communal Environmental-Climate Governance, 2. the Energy Commune Program of the Energy Sustainability Agency, and 3. the communal water strategies of the Agency for Sustainability and Climate Change (ASCC). However, it is essential to remember that the elaboration and implementation of the documents mentioned above, as well as strategies, involve mobilizing resources, gathering information, and installing capacities that depend on the institutional capacity of each commune. This can mean widening existing gaps, resulting in different levels of adaptation and resilience to climate change in their territories. Indeed, significant differences are already revealed in the degree of preparation and action of local governments in the face of risks associated with climate change, as well as in the degree of updating and implementation of their territorial planning and management instruments (in some cases, such as Rapa Nui, that have not updated these instruments for several decades).
Final Reflections
Cities are not uniform entities in terms of their climate and environmental quality. Unequal urban and environmental characteristics, combined with disparate population capacities and resources, generate marked climate inequality within urban boundaries. Not all people experience the same level of environmental quality; consequently, the climate threats to which they are exposed vary considerably.
Those who lack access to resources such as housing and air conditioning, for example, are in a situation of greater vulnerability and, therefore, at greater risk in the face of adverse climatic conditions. Differences in resources and capacities are also observed at the communal scale. Local governments vary in their ability to respond and prepare for climate and climate change challenges, resulting in unequal levels of adaptation and resilience.
Recommendations
- Promote the creation of climate refuges in the city. These spaces, which could be both open (parks, squares) and closed (gyms, libraries), would provide thermal comfort and strengthen community bonds.
- Incorporating better materials, natural ventilation, and other measures in urban planning and design can significantly increase society’s adaptive capacity to high temperatures. This can also generate co-benefits by mitigating heat, increasing thermal comfort, and reducing energy needs, thus contributing to climate change mitigation.
- Implement nature-based strategies that include green infrastructure. However, these must be carefully evaluated to avoid negative impacts, mainly related to water availability.
- From a public health perspective, evidence-based strategies are urgently needed to address the health risks associated with exposure to extreme heat. These strategies should have a long-term territorial perspective rather than a short-term individual approach, such as using air conditioning or fans, which, while convenient, does not promote resilience in a lasting way.
- Build low-carbon and climate-resilient development agendas through networking, reduction of regional disparities, exchange of good practices, generation of public policies that arise from the territories, continuous improvement of processes and evaluation mechanisms, expansion of binding decision-making spaces, and promotion of the democratization of technical-scientific knowledge.
- Considering that the effects of high temperatures can quickly become life-threatening, especially for those vulnerable groups of the population (including older adults, children, pregnant women, people with chronic diseases, and those groups or individuals of lower socioeconomic level or who are socially isolated), public policies must focus on climate-sensitive urban planning, considering the design of public spaces that provide – from a climate justice perspective – access to shade, wind or sun protection. It is necessary to generate means that allow cities to adapt, improve their quality of life, and ensure the health of their populations.
References
Alcoforado, M., Andrade, H., Lopes, A., & Vasconcelos, J. (2009). Application of climatic guidelines to urban planning: the example of Lisbon (Portugal). Landscape & Urban Planning, 90(1-2), 56 – 65.
Bulkeley, H. (2013). Cities and climate change. Routledge.
Sarricolea, P., Smith, P., Romero-Aravena, H., Serrano- Notivoli, R., Fuentealba, M., & Meseguer-Ruiz, O. (2022). Socioeconomic inequalities and the surface heat island distribution in Santiago, Chile. Science of the Total Environment, 832, 155152.
Schlosberg, D. (2013). Theorising environmental justice: the expanding sphere of a discourse. Environmental politics, 22(1), 37-55.
Smith, P., & Romero, H. (2016). Factores explicativos de la distribución espacial de la temperatura del aire de verano en Santiago de Chile. Revista de Geografía Norte Grande, (63), 45 – 62.
Williges, K., Meyer, L. H., Steininger, K. W., & Kirchengast, G. (2022). Fairness critically conditions the carbon budget allocation across countries. Global Environmental Change, 74, 102481.
Notes
[1] Information on surface heat islands in Chilean metropolitan areas and larger medium-sized cities is available on the resilient cities’ platform developed by the Center for Climate and Resilience Research CR2 at the following link: https://ciudadesresilientes.cr2.cl/isladecalor
[2] Cities between 100,000 and 299,999 inhabitants (Minvu, 2017)
