Definition and characteristics of climate-adaptive cities: a systematic review

This study encompassed published articles and books addressing the definition, characteristics, and features of climate-adaptive cities within the scope of the research questions. The inclusion of articles and documents was not restricted by time, covering works available until March 6, 2018. It is crucial to clarify that while there was no limitation on the publication date of included materials, the retrieval process and study focus encompassed documents available until the specified date. Following the collection of studies, the examination of entered studies commenced and persisted until August 26, 2021. Excluded were studies not addressing the definitions or characteristics of climate-adaptive cities, those solely examining other components, studies unrelated to events, disasters, accidents, or crises, and articles not related to a human population residing in a specific geography. Additionally, documents not available in full text and not relevant to our research topic, as well as studies not in English, were excluded.

This systematic review utilized available books, manuals, guidelines, and scientific resources, as well as electronic searches on various websites and databases available on the Internet, including PubMed, Web of Science, EMBASE, Cochrane Library, Scopus, ScienceDirect, and Google Scholar, without any limitations on the date or type of study. The language of the research in the above-mentioned databases was English. In addition to these databases, reputable international websites, such as those affiliated with the United Nations (UNDP, UN-HABITAT, UNISDR, UNEP), were also examined. Moreover, articles on Google Scholar were searched manually. Reading the articles' references and using the snowball mechanism were other methods used to find relevant articles. This study was conducted on March 6, 2018.

The following English keywords and their similar terms extracted from the MeSH database or the Tazaroos database, which is specifically designed to identify synonymous terms, were used. It should be noted that consultation and agreement with experts and stakeholders were carried out before the search regarding the keywords and types of terms. In general, only two groups of words were used to increase the study's sensitivity, which are:

Based on the inclusion and exclusion criteria, the researchers (AY, AM, HA, MN, NY, AM, SHS) screened the titles and abstracts of the retrieved articles using the EndNote software to find relevant articles. Then, the full-text of the selected articles was independently reviewed by two researchers (AY, AM). In case of disagreement between the two researchers, a third researcher (AOT) resolved the differences and helped them make the best selection. The process of reviewing and selecting articles is shown in Fig. 1.

The quality of the articles was evaluated by the researchers using the Critical Appraisal Skills Program (CASP), which provides a systematic way to evaluate the overall quality, reliability, and quality of different study designs [25, 26]. CASP provides a structured framework for assessing key aspects such as research methodology, sampling, data analysis, and result reporting.

Each article underwent a detailed evaluation based on specific parameters outlined in the CASP criteria. These parameters encompassed methodological rigor, validity of findings, appropriateness of statistical methods, and the clarity of reporting. The evaluation process resulted in the categorization of articles into three quality groups: low, moderate, and high. Documents and articles that were categorized in the low-quality group were excluded, and articles categorized in the moderate and high-quality groups were included in the study. This thorough quality appraisal process aimed to uphold the integrity and credibility of the included studies, ensuring that the findings synthesized in the systematic review are built upon a foundation of methodologically sound and reliable research.

The extracted data was recorded in two separate forms. The first form included general characteristics of the article, such as the article's identification number in this study, title of the study, first author of the article, year of the study, type of study, country or city where the study was conducted, the subject matter extracted from the article for the present review, and the study's objective. The second form was related to the extraction of definitions and features of climate-resilient cities. Then, descriptive and thematic analysis was performed for the selected articles and texts. In this study, the authors coded the extracted descriptive information, definitions, and features of climate-resilient cities. Then, similar codes were grouped together. Finally, the grouped findings were analyzed for categorizing these strategies. The accuracy and completeness of the extracted data were discussed by the research team in a group discussion.

The reviewed articles were primarily from the United States, accounting for approximately 18.42% of the total. Canada contributed around 7.89%, both individually and as part of a joint article with Saudi Arabia. Australia and England followed closely, with approximately 15.78% and 10.52%, respectively. Thailand comprised about 5.26% of the articles. Other countries collectively contributed approximately 42.13% of the total. Regarding the types of articles, original articles constituted the majority at around 39.4%. Case studies followed, representing about 21.05%, and review articles accounted for 7.8%. Additionally, there was one mixed review and case study, making up approximately 2.6% of the total. Furthermore, two books, two surveys, and two theses were identified, each contributing approximately 5% to the overall distribution.

51.3% of the reviewed articles referred to the characteristics of climate-adaptive cities, 2.3% to the definition of resilience, 20.6% to the definition of adaptation, 10.4% to the definition of climate-adaptive city, 7.7% to the definition of adaption to climate change, and 7.7% to both the definition and characteristics of climate-adaptive cities. The specifications of the entered articles are shown in Table 1.

Given that this study focuses on defining and outlining the characteristics of climate-adaptive cities, the thematic analysis begins by separating codes related to the definitions of adaptive cities from those related to their features. Following this division, codes within each category are further classified into relevant subcategories. Both categories are integral to our understanding, as the definitions aim to articulate what constitutes an adaptive city, while the characteristics elaborate on the specific attributes of such cities. In essence, characteristics serve as complementary elements, providing detailed insights into the nature of adaptive cities.

A total of 75 codes were extracted from 38 articles, including 55 codes related to the characteristics of climate-resilient cities and 20 codes related to definitions. The highest number of codes in the category of features of climate-resilient cities was related to the subcategory of effective resource management with 18 codes. In the category of definitions, the highest number of codes was related to the definition of resilience with 16 codes (Table 2). In this review, only four definitions of climate-resilient cities were extracted. It should also be noted that the subcategories of stakeholder participation and knowledge utilization had the lowest number of codes with only three codes among the subcategories in this review. Based on this study, many of the features of climate-resilient cities were extracted from the experiences of resilient cities or cities that have taken steps in this regard.

According to definitions of climate adaptation, it is a multidimensional, location-based challenge [43]. In fact, adaptation to climate change is a process [65], and in another definition, it is the coordination between future climate change scenarios and current change strategies and programs [33]. Some definitions of climate adaptation refer to capacities, which are sustainable and the abilities of communities to cope with environmental changes [34], or the capacity of a system, society, or community to resist or adapt to a risk, to achieve and maintain a level of performance and structure [36]. However, the capacity for adaptation is more interpreted as the ability of stakeholders, individuals, groups, and systems [30]. In another definition, climate adaptation is defined as learning to live with severe weather events, changing weather patterns, and preparing for some unavoidable changes [44]. From the health perspective, adaptation is a responsive action for public health, which is necessary to prevent, reduce, and manage climate-related risks [42]. In fact, climate adaptation is the adjustment of natural or human systems to real or potential climate stimuli or their effects, mitigating damages and taking advantage of opportunities [35] and results in preventing or reducing vulnerability to climate change [28].

Although there are numerous definitions regarding adaptation to climate change, the definitions of climate-adapted cities are limited and very few. Moreover, none of these definitions are comprehensive, applying solutions to change and reducing the effects in a timely and effective manner before uncontrollable changes occur, and learning from non-adaptive ways used by other cities for defining climate-adapted cities [37]. In this definition, solutions are generally mentioned, while clarifying this issue is very important. Another definition mainly refers to reducing social vulnerability and emphasizes the importance of bottom-up adaptation [39], while ignoring other characteristics of climate-adapted cities.

In another definition, a climate-adapted city is defined as a city that can only maintain stability against heat islands [32]. Although this definition is in line with the global Paris Agreement aimed at global adaptation, it cannot be considered a comprehensive goal. This goal seeks to ensure sufficient adaptation response to the global temperature goal, ultimately leading to sustainable development [20, 66]. Finally, a relatively better definition of urban resilience to climate change is as follows: the flexibility of the capacity of individuals, communities, institutions, businesses, and systems within a city to survive, adapt, and grow regardless of the chronic stress and acute shocks they experience [39]. Therefore, based on the characteristics of climate-adapted cities and the texts reviewed in this study, it can be suggested that a climate-adapted city is a city that, through effective resource management, future-oriented planning, education, knowledge utilization, innovation in governance and industry, decentralized management, and low-carbon economy, leads to adaptation, resilience, sustainability, and flexibility of the capacity of individuals, communities, institutions, businesses, and systems within a city, against all impacts of climate change and reducing the resulting consequences.

In the literature review conducted in this study, no specific study was found to investigate the characteristics of climate-adapted cities. Nevertheless, determining the features, characteristics, and standards of adaptation can be highly effective in assessing its efficiency and categorizing the factors that foster adaptive capacity.

Identifying adaptation criteria is often challenging for development interventions, which can lead to difficulties in classifying whether anything that creates adaptive capacity can be called adaptation [67, 68]. Therefore, in this review, all variables and factors that can be considered as characteristics of a climate-adapted city were extracted and categorized in a scientific and systematic manner.

Based on the literature review and considering the effective role of social coordination in resilience [59], one of the characteristics of climate-adapted cities is the use of participatory techniques, including local stakeholders [50] and community participation [45, 54]. Friend (2010) also considers community participation as a prominent feature of climate-adapted cities [54]. Although this participation should be comprehensive, Al-Zubari et al. (2018) only referred to the necessity of stakeholder participation in achieving proper water resources [45]. However, the community-based adaptation process in climate-adapted cities involves engaging other institutional elements in decision-making, ensuring the compatibility of top-down planning with local needs, and using participatory research to facilitate the participation of local communities in shaping adaptation planning processes [21]. Therefore, it can be said that community-based adaptation can provide an opportunity for people's participation in planning and adaptation activities in a comprehensive and proper manner. Facilitating people's participation leads to understanding and enhancing their awareness of their risk, vulnerability, and resilience to climate change [69].

Effective resource management [45, 47] and efficient use of limited resources [30, 47] are among the most important characteristics of climate-adapted cities. Al-Zubari (2018) [45] emphasizes the need to create sustainable strategies by estimating the assessment of each household's contribution to global warming based on different lifestyles and climatic conditions in different parts of the world, as well as reducing energy consumption to control greenhouse gas emissions [45]. This highlights the importance of resource management for achieving effective adaptation. This adaptation strategy may vary across different climates, as individuals' thermal responses to a consistent thermal environment differ from one location to another [70].

Kilkis S (2016) [47] also highlights the importance of sustainability, resource management, and the judicious use of resources in climate-adapted cities. He argues that achieving sustainable development in cities requires attention to factors such as energy consumption, carbon dioxide emissions, transportation systems, waste management, water resources, socio-economic capacity, and inter-sectoral sustainability [47]. Although, the current global progress and sustainable initiatives, as outlined in international frameworks such as the Paris Climate Agreement and the United Nations Sustainable Development Goals (SDGs), are not advancing rapidly or at the expected pace in reducing greenhouse gas emissions and addressing climate change. In other words, advancements in these areas are encountering challenges and obstacle [71].

In line with the focus on transportation systems, Garg (2001) writes in his article that since greenhouse gases SO2 and NOx in Indian cities are more emitted from industries, focusing on transportation systems as sources of greenhouse gas emissions will have a higher cost-effectiveness in reducing emissions [57]. Based on the above, it can be concluded that reducing greenhouse gas emissions from urban transportation systems is one of the characteristics of climate-adapted cities, which will also lead to economic benefits.

In his study, Quay R (2010) presents the characteristics of different cities based on a review of their experiences. For example, the city of Denver has developed a water adaptation planning process based on scenarios, while New York City has developed new strategies for water and sewage systems and flood control to enhance their resilience to climate change [63]. In addition to these, other solutions for effective resource management towards climate adaptation have been mentioned, including: effective energy use management through wind catchers, chimneys, summer spaces with dome or elevated ceilings, courtyards, basements, underground water tanks, and natural refrigerators [52]; access to vegetation coverage [62]; centralized sustainable water management [55]; lifestyle change and proper use of resources [30]; low-carbon technologies and new energy sources [56]; focusing on cost-effectiveness in reducing greenhouse gas emissions [57]; reducing energy consumption to control greenhouse gas emissions [45]; and the use of renewable energy sources [72] for climate adaptation in urban areas.

One of the most important characteristics of climate-adapted cities is foresight, future prediction, and planning for the future to achieve effective adaptation. In this regard, Alhashmi et al. (2017) emphasizes the need for planning to reduce the use of fossil fuels and use renewable energy sources such as solar, wind, nuclear, and biomass to reduce carbon emissions [46]. Nanos and Filion (2016) also point to the importance of foresight in climate adaptation planning, considering resilience and executive criteria to assess the flexibility and vulnerability of urban drainage networks in Kingstone. They argue that this can be achieved through forecasting and designing models for hard weather periods to assess how a storm will behave in the future [49]. Carrero et al. (2013) also mentions the characteristics of foresight, stakeholder participation, and resource management. In his article, he emphasizes considering the economic dimensions in climate change policy planning, identifying stakeholders and their participation, and having a future-oriented approach as effective factors for management [50]. Additionally, Keenan et al. (2016) includes foresight and collective response to current conditions as characteristics of resilience [29]. Therefore, foresight, resource efficiency, and proper resource management can be considered essential for cities to achieve climate adaptation.

One of the key characteristics of climate-adaptive cities is education, which involves teaching adaptation strategies at all levels. THP (2017) suggests using social media to increase local farmers' adaptability and learning to enhance resilience to climate change. Therefore, it can be concluded that education and capacity building on effective adaptation strategies and changes in lifestyle and resource use are critical for climate adaptation [30]. Geirsdóttir et al. (2014) emphasizes the importance of community awareness of their living conditions in climate adaptation. For example, knowledge of past communities in reading weather signs and sea changes had prepared them to react to hazards and raised their preparedness level [59]. In conclusion, numerous adaptation strategies and solutions can be taught to communities to enhance their participation in climate adaptation. Therefore, one of the characteristics of climate-adaptive communities is to pay attention to the following while teaching adaptation strategies: using learning methods and teaching techniques appropriate for the community's culture and awareness level, using social media capacity, using virtual spaces and modern teaching methods, and engaging local leaders and educators for education.

The gap between knowledge and action in the field of climate change has made it difficult to understand and establish a relationship with it [73]. Tapan Kumar Dhar (2016) [35] believes that using indigenous, interdisciplinary and community-based knowledge along with governmental collaborations, as well as integrating physical and socio-environmental characteristics, are necessary for successful adaptation [35]. Therefore, it seems that the use of indigenous knowledge and interdisciplinary research [35], is one of the necessities for achieving climate-adaptive cities. Community awareness of their living conditions can play a significant role in identifying and interpreting environmental changes, which can enhance their preparedness and response to climate change hazards [59]. In this regard, Odemerho emphasizes the importance of utilizing the experiences and human knowledge of flood-prone areas to adapt to floods and recognize the dominant type of flood and its root causes [74, 75]. Overall, it can be inferred that utilizing knowledge, especially interdisciplinary, local, and indigenous knowledge, and utilizing past experiences are characteristics of climate-adaptive cities and can enhance their awareness, preparedness, and adaptation to climate change.

Governance [30] and industry play a crucial role in enhancing the resilience of communities to climate change, and innovation in these areas is one of the key characteristics of climate-adaptive cities. For example, Guangkuo Gao (2015) [56] considers the development of low-carbon policies through industrial structure, innovation in governance, low-carbon technology, incentive mechanisms, and new energy supply as characteristics of climate-adaptive cities [56]. Based on the review conducted in this study, other examples of innovation in governance and industry include: increasing the resilience of local water resources with a bottom-up approach in decision-making [60], low-energy consumption through sustainable house design [61], attention to energy and carbon dioxide emissions, transportation systems, waste management, water, social-economic capacity, and intersectoral sustainability for achieving sustainable development in cities [47], and attention to resistance and capacity building [51]. Therefore, the adaptation of climate-adaptive cities requires the creation, expansion, or imitation of innovative strategies and plans for climate adaptation in governance and industry. This issue, including some insights on corporate social responsibility, should receive the attention and support of policymakers and industry leaders.

Another characteristic of climate-adaptive cities is decentralized management. One example of this is decentralized urban risk management [53, 58]. For instance, decentralization of urban risk management in the central system in Vietnam is an example of decentralization [53]. One aspect of climate adaptation is decentralized planning based on local risk assessments. Moreover, decentralized management signifies the involvement and participation of communities in decision-making. In this regard, Gonzales (2017) argues that a bottom-up approach in decision-making can help increase the resilience of local water resources [60]. Furthermore, increasing the capacity of local governments to assist the adaptive growth of people, especially farmers, to environmental changes has been recommended [30].

One of the prominent features of climate-adaptive cities is a focus on a low-carbon economy [64]. Li (1995) identifies the creation of green jobs, the possibility of transforming existing jobs into green jobs, and the ability to continue working under lower consumption conditions as examples of a low-carbon economy [76]. In this regard, it is also possible to mention the imposition of taxes on carbon dioxide, its trading, and investment in wind, solar, water, biomass, and other types of renewable energy [56] should be promoted. Although recent studies on the transition to a global low-carbon economy or decarbonization are not encouraging, as both human and natural carbon dioxide emissions are increasing due to human factors [77], attention to this issue is essential for climate-adaptive cities. In summary, a low-carbon economy is critical for reducing greenhouse gas emissions and addressing climate change. Climate-adaptive cities must prioritize the development of a low-carbon economy to reduce their carbon footprint and promote sustainability.

The main limitations of this study were associated with the extended duration of the project. This study was part of a larger systematic review. Due to the substantial scale of the overarching project, the execution time of the work and its completion extended. While the implementation date is specified in the methodology, the prolonged duration can be justified to some extent given the significance of the climate change issue and the contemporary nature of the topic. Another limitation pertained to accessing articles. Some articles were not readily available, prompting researchers to attempt retrieval through contacting authors, purchasing articles, or utilizing accessible academic databases.