Heat and the city: Thermal control,governance and health in urban Asia

Why heat?

This special issue focuses on the under-studied but increasingly pressing issue of urban heat. Cities are getting hotter, both due to the global crisis of climate change, and the related phenomenon of Urban Heat Islands (UHI), which locally amplify increased global temperatures and exposure to solar radiation. We know a great deal about how heat is affecting cities from a scientific and public health perspective; indeed, the STEM literature on the UHI effect is immense and constantly growing (Marx et al., 2021). Urban studies scholarship, however, has been slower to foreground heat as a social, spatial, and political category of analysis, at least in comparison to discussions of carbon emissions and their control, energy and infrastructure, rising sea levels or flooding, and activism towards sustainability. While many of these themes also figure in the following collection, our focus is on the varied phenomena of urban dwellers feeling, avoiding, suffering under, mitigating, culturally interpreting and attempting to anticipate and plan for, the reality of elevated air temperatures and solar radiation. What we call thermal control, governance, and health is the multi-level and multivalent social and material response to uncomfortable and potentially injurious temperatures, an elusive topic which this special issue makes visible and constitutes what we hope will be an ongoing urban research agenda.

We argue that the myriad challenges posed by heat cannot be fully met until the thermal environment of cities is made an interdisciplinary concern in its own right, a consensus already reached in regard to the larger, related crisis of climate change (Castán Broto et al., 2020). Climatologists have identified the problem of the UHI effect (Howard, 1833; Peppler, 1929), geographers and architects have studied the thermal transformation of urban landscapes (Castán Broto, 2017; Munro and Grierson, 2012; Chow and Roth, 2006), public health specialists have explored heat stress and its epidemiology (Jay et al., 2021), and urban historians and ethnographers have chronicled the socially selective effects of heatwaves (Keller, 2015; Klinenberg, 2015). More recently, urban planners have also emphasised the importance for cities to engage with heat governance through design and planning interventions, such as the provision of shade infrastructure (Keith et al., 2023; Meerow and Keith, 2022; Turner et al., 2023), as a part of the emerging scholarship on ‘critical heat studies’ or ‘critical temperature studies’ (Hamstead, 2023; Starosielski, 2021). Yet this existing research landscape has been inadequately integrated, with significant gaps and uncharted overlaps in themes and objectives (Khosla et al., 2020). Our collection advances this integration by bringing together the work of historians, sociologists, anthropologists, architectural theorists, geographers and science & technology studies (STS) scholars around heat as a named urban problem of great contemporary relevance, with an inevitably long future, but also with a largely unexplored past.

The linked themes of the volume are how urban dwellers attempt to control their exposure to heat, how this control is affected for better or worse by governance regimes and how the interaction of both scales functions as a determinant of urban health. Our papers range across scales from informal street vendors engaged in shade-seeking behaviour in Karachi to urban planners in Bangkok stymied by bureaucratic inertia and political neglect. We also foreground history as a source of both legacy and radical change, such as the urban transition from informal ways of mitigating heat in the cities of southern China to the use of artificial cooling. A number of papers in our collection deal with everyday practices of living with heat, excavating down to the choices urban dwellers make of how and where to shelter, what cooling technologies to purchase and how these and other choices are constrained or advanced by governance regimes. Others discuss how heat is (and is not) accounted for in urban planning, and yet is always one of its products. Still others explore how the concept of heat has multiple cultural codings, for example in ‘traditional’ Chinese medicine, subverting the idea of a universal human reaction to or interpretations of, heat as a simple temperature reading. In sum, the volume explores how different cultural, social, technical, design and planning practices interact to relieve, exacerbate and interpret the meaning of heat in urban settings.

Why urban Asia?

The beginnings of a sustained urban studies interest in heat can be traced largely to the brutal heatwaves experienced by cities in the Global North over the past 10–15 years (Habeeb et al., 2015; Marx et al., 2021). The comparative newness yet more frequent occurrence of such events in cities like Paris (Keller, 2015) and Chicago (Klinenberg, 2015) during this period has, more than any factor, made global warming ‘real’ for urban residents of temperate zones. It is, however, just as real and potentially more devastating for cities in the tropics and semi-tropics, despite their centuries-long experience with elevated temperatures (Im et al., 2017; Kang and Eltahir, 2018). In fact, recent reports have highlighted that urban temperatures in the hot climatic regions are projected to increase more than those of cities in the Global North. These high temperatures and more intense heat waves in tropical and subtropical cities will be further exacerbated by inadequate cooling infrastructure in most of them (International Energy Agency, 2018; Sustainable Energy for all, 2019). Our volume thus widens this nascent scholarship to include some of the hottest cities on Earth, located in a belt across the continent of Asia between the equator and (roughly) latitude 30° north: Doha, Karachi, Ahmedabad, Bangkok, Singapore, Chongqing, Wuhan and others. These cities have always been hot by global standards, but climate change and the UHI effect have now lifted temperatures in each to unprecedented levels, in some cases approaching the limits of human endurance, that is, maximum summer temperatures of 40°C and higher. Most (though not all) of the cities we consider are simultaneously dealing with rapid urbanisation, an increase in carbon emissions and an erosion of existing green space (Harlan and Ruddell, 2011). Many also contain an abundance of those classes of people most vulnerable to heat-related illnesses: the elderly, children, and the poor (Ebi et al., 2021). This combination of factors marks them as essential sites in the growing but still formative discussion of heat as a critical factor shaping urban life.

We write in and about Asia with the awareness that heat has, historically speaking, been over-determining in Western constructions of this continent, including its cities. For the geographer Ellsworth Huntington (1924), most of urban Asia lay in the torrid zone, where heat was the direct enemy of ‘civilisation’. The only explanation he could conceive of for the rise of historic urban centres in tropical and semi-tropical locations was that their climates had been more temperate in the distant past. The orientalist and colonialist linkage between climate and race has a history both pre-dating and post-dating Huntington (Arnold, 1996), and has even been expanded upon by Asian theorists, such as Watsuji (1961). Nor has it entirely disappeared in contemporary discourse, despite some cities in Asia’s southern tier now being among the most economically productive and high-tech on the planet (as some also were in previous epochs). A commonly cited explanation for the economic success of modern Singapore, for example, is its widespread adaptation of cooling technology, hence turning it into an ‘air-conditioned nation’ (Chang and Winter, 2015). This was popularised by the first Prime Minister of Singapore, Lee Kuan Yew, who believed that the ‘tempering’ of the indoor climate by mechanical cooling helped the city-state overcome a hot climatic barrier to productive work and socio-economic development. Such climatic/technological determinism not only overlooks the myriad other successful solutions Asian cities crafted to deal with heat and climate in daily life before (and into) the modern period but ignores the still-existing economic and social disparities within and among air-conditioned centres in the same climatic zones, and their varied access to networks of global capital.

Heat (and cold) have actively shaped the configuration of urban life and infrastructures for as long as cities have existed (Lefebvre, 2013). The citizens of Asia’s tropical and semi-tropical cities thus have substantial histories of engagement with heat, which has to be factored into any discussion involving their current thermal control, governance and health. Indeed, the increase in the length and severity of heat waves in cities outside Asia makes the issue of how Asian urban cultures govern, discuss, endure, mitigate and cope with heat even more globally relevant. Heat is thus an urban issue that transcends global climate change per se, although the current and ongoing climate crisis has made its study more crucial.

Heat as science and culture

The thermal environment of cities, we argue, affects nearly all aspects of their existence. Heat as an analytical category in the urban context arises most transparently in scholarship on the Urban Heat Island (UHI) effect, and increasingly in the planning literature (Corburn, 2009; Gabbe et al., 2024; Turner et al., 2022). Most UHI research, however, is conducted within a STEM framework of what Starosielski (2021: 2–8) calls ‘thermal objectivity’, aiming to pinpoint how and at what rates heat is increasing, and what technical solutions can be used to measure and mitigate. Our papers are informed by UHI scholarship but go beyond its frame to consider urban heat over longer historical periods, as a political and cultural condition as well as a physical one and as having a role in shaping (or further sustaining) urban social structures. Of the available solutions to high heat, the ones most common in cities today tend to be the most energy-intensive and least sustainable (Winter, 2016). An increasing number of people in heat-prone and humid cities have abandoned well-shaded and naturally ventilated buildings, for example, in favour of hermetically sealed climate-controlled apartments and office spaces (Barber, 2020; Chang, 2022; Sahakian, 2014). While air-conditioning tackles the problem of heat on an individual level, it makes the collective situation worse in a vicious cycle (Jay et al., 2021).

Until recently, urban planning has likewise paid inadequate attention to the thermal environment, thus contributing through action or neglect to making heat a social justice issue. While ‘climate urbanism’ has become a new urban paradigm in the Global North (Castán Broto and Robin, 2021; Long and Rice, 2019) its take-up in the Global South has been slower and more sporadic (Rahman et al., 2023), and the social inequality issues that it highlights are in many instances even more intractable. Even with an increasing global (and urban) consensus on methodologies and solutions at the governance level, as Zoe Hamstead (2023) points out, ‘there has been little effort to understand the embodied and lived experience of heat’ (p. 153). ‘Narrowly defining heat as a “meteorological state” subject to technocratic governance she continues, tends to ‘invisibilize human heat experience’ (Hamstead, 2023, p. 154). That heat itself is invisible to the eye adds another layer of complexity to attempts to define it beyond temperature readings, or mortality statistics following a heatwave.

Heat and cold also have a variety of cultural meanings that extend beyond temperature, particularly in many Asian traditional medicines (from Ayurveda to Chinese medicine) and related dietetic systems, as pointed out by Chee et al. (2024, this issue). Such readings have survived within Asian modernity both informally and, in some places, at the level of governance. This strongly suggests a need for more historically informed ethnographies of heat (Venkat, 2020) at various scales, and interrogating cultural understandings of what heat is and means. Culturally specific understandings of heat are not set apart from universalising science-based ones, however, but interact with them at every level, including individuals’ self-diagnoses of discomfort and decisions about what to eat and drink.

Planning for heat

The most sustained forum for discussion of urban heat has probably been the planning literature, and the response of city planners to heat is the subject of the first four papers. In ‘Scale and Modularity in Thermal Governance’, Khandekar et al. (2024) introduce the theme of thermal governance in urban India through the medium of the Heat Action Plan (HAP). First drawn up for the city of Ahmedabad in Gujarat (one of the hottest parts of the Indian subcontinent), this initial planning model was carefully crafted, according to the authors, with due consideration of local social and environmental conditions. Its virtue was also its shortcoming, however, as it was then ‘scaled up’ and ‘modularised’ in 30 other Indian municipalities with little allowance for their own social, political and planning situations. Two of the ‘modules’ most commonly replicated were also the most problematic, namely categorising heat waves as ‘disasters’ (and thus circumscribed in time) and reducing local data-gathering to mortality and illness statistics. Both approaches allowed Indian cities to ignore the more long-term factors that construct local thermal vulnerability, such as poverty, poor housing and urban design, distancing the HAPs and the agencies they activate from ‘the everyday realities of local practices’. The result was to favour short-term emergency response regulated by temperature readings on the one hand and mortality statistics on the other. Likewise, even the model HAP crafted for Ahmedabad failed to recognise the ‘ingenuity and resourcefulness of the local populations’ in sustaining heat-reducing practices, instead classifying ‘cultural norms’ as a factor increasing vulnerability.

Continuing the theme of thermal governance, Marks and Connell (2024) take us deep into the planning culture of Bangkok, a city beset with huge challenges in reversing an intensifying UHI. Adopting an urban political ecology approach, the authors interviewed over a dozen planners, architects, realters and other parties involved with Bangkok’s urban development culture, describing as ‘Unequal and Unjust’ a process of city-building which inadequately plans for ever-rising heat levels. Among major Asian cities, the Thai capital has one of the lowest amounts of green space per capita, unchecked levels of private vehicle usage (and exhaust), and burgeoning population growth. It is also one of the largest cities on Earth without a master plan, making planning itself more of a ‘symbolic ritual’, subject to business and political manipulation favouring the wealthy and middle class over the poor. While the middle and upper classes create most of the city’s UHI burden through car usage, building with concrete and heavy use of air conditioning, the poor bear the brunt in terms of un-comfortability and ill-health. Bangkok’s UHI is thus categorised by the authors as a neglected site of injustice and inequality, which they interrogate in order ‘to tease out the actors and processes that produce these risks’.

‘Urban Heat Islands and the Transformation of Singapore’, the next article by Jung (2024), offers a stark contrast in thermal governance and planning to Bangkok, although the end result has still been an increasing UHI. The city-state was shaped by strong planning regimes from its beginnings, first as a British colonial port and then under a succession of masterplans in its post-colonial period. Jung elucidates how Singapore’s UHI was expanded by each of these plans, the cumulative effect being to spread it beyond its original urban core to cover most of the island’s formerly rural regions. The major contributor to the expansion of Singapore’s UHI was not the build-up of industrial areas, however, but the spread of high-rise ‘new towns’, whose ‘urban canyon’ effect had more consequence for heat than generally low-rise industrial estates. Alleviating heat was not a major consideration in Singapore’s master-planning until this century, although, unlike Bangkok, Singapore had a colonial inheritance of public parks and botanic gardens which the current government has more recently leveraged in re-inventing the city-state as ‘green’. Although not discussed by Jung, a practice of tree-planting begun and strongly promoted by the city-state’s founder, Lee Kuan Yew, has also embedded that practice more deeply into local culture than in most Asian cities. Whether enhanced tree-planting and more high-tech efforts such as creating a Digital Urban Twin of the city to model heat-mitigation strategies will reduce 21st century Singapore’s UHI ahead of global warming remains to be seen.

Doha offers a still different thermal planning picture than Singapore, Bangkok or the cities of India, according to the fourth article by Chang (2024). Here the author’s emphasis is on ‘Thermal Governance, Urban Metabolism, and Carbonised Comfort’, the process by which hydrocarbon, as both an energy source and a commodity, is turned into air-conditioned urban fabric in the Gulf states. Chang reveals that mechanical cooling arrived in the Gulf as early as the 1940s with the establishment of oil towns by foreign petroleum companies, which provided the template for urban development in the region. These enclaves embodied an extreme thermal contrast between the air-conditioned houses and workspaces of the technical and political elite and those of workers (what the author calls a ‘race-based system of thermal privilege’), one that has continued as imported foreign labour has taken over the risk of working outdoors in extreme desert heat. The petrodollars generated by oil and gas have allowed the creation of cities ‘with highly uneven spatio-temporal distribution of urban temperatures’, a pattern we see replicated to different degrees in most of the cities covered in this issue. Doha, however, like other cities flush with petrodollars in the region, has had the resources to heavily subsidise the cost of electricity. This has resulted in overcooled spaces, an early and emblematic example of which was the Sheraton Hotel and Conference Center of 1982, which the article discusses in some detail as among the first of the city’s signature architectural landmarks to radically break from traditional approaches to establishing thermal envelopes.

Heat on the street

While planning dominates the study of heat in social science literature, historians and ethnographers, sociologists and others have increasingly turned their attention to heat at the street or neighbourhood level: what it feels like, what actions it elicits, how it consolidates and fractures social groups and how its cultural meanings extend well beyond its definition as a temperature reading. In ‘Hot Climates in Urban South Asia’, Macktoom et al. (2024) bring analysis literally to the level of the street, or more specifically shade-seeking behaviour by Karachi street-vendors. Citing Mike Davis’ contention that shade is an inalienable right (Davis, 1997), the authors point out that this is still far from true in Karachi, where shade has to be negotiated and in some cases even paid for. In a city of 16 million people which has lost 40% of its green space since 2001, and where summer daytime highs can reach 42 degrees C, accompanied by high humidity, street-venders are among the most vulnerable classes of worker. Within these strained conditions, the authors reveal, shade-seeking sorts workers into hierarchies based on their abilities to occupy favoured shaded spots (sometimes with the enforcement of the state), while in other instances shade has to be forfeited in favour of proximity to customers. Still other workers, tasked with clearing vendors from shaded areas, suffer under the comparatively heavy uniforms of security guards. Although Karachi adopted the Ahmedabad HAP, the article demonstrates the truth of the warning by Khandekar et al (2024) that such plans are inadequate to the extent that they ignore local conditions, particularly the everyday lives of the most vulnerable and the long-term and deeply institutionalised processes that create thermal injustice.

Further deepening our understanding of heat from the perspective of affected bodies, the article by Courtney (2024) on Wuhan traces an historical arc from the Mao era to the present day and from the materiality of bamboo beds to room air conditioners, literally ‘The Birth of Cool’. Academic accounts of the dramatic transitions in Chinese society over the last half-century generally ignore temperature and thermal comfortability, Courtney points out, although popular narratives of the same period, at least in the city of Wuhan and elsewhere in southern China, focus on these same phenomena. Wuhan has transitioned from a city where virtually the entire population slept outside communally in order to mitigate summer heat, to one where everyone has been forced into their own apartments and bedrooms at least in part by the social adoption of room air conditioners. And as in other cities we have considered, interior air conditioning produces external heat which helps make the Wuhan UHI hotter than it ever was, despite its already historic reputation as one of China’s ‘great furnaces’. Courtney traces what he calls the ‘dialectical relationship’ between air-conditioning and socio-economic reforms, an overlooked factor marking if not contributing to the gradual decrease in communal living and sensibilities, and the ‘shift away from the older culture of the street’ in the Deng period and after.

Kobi’s (2024) article on the nearby Chinese city of Chongqing serves as a valuable companion piece to Courtney’s, affirming many of his observations about the Mao period and after within the frame of a contemporary ethnographic account of the city’s ‘material culture of cooling’. Like Wuhan, Chongqing is one of China’s ‘great furnace’ cities and has similarly made a transition from communal outdoor sleeping to indoor private sleeping with room air conditioning. Following Castán Broto (2019), the author traces an ‘Urban Energy Landscape in Practice’, concentrating on ‘the close relation between the human body, built environment, and energy infrastructure’ over time, and the way they shape everyday thermal rhythms. Her landscape extends from the Three Gorges Dam at one extreme, providing cheap electricity for the city’s burgeoning population of air conditioners, to the use of underpasses for shade by the urban poor.

Rounding out the issue, the article ‘Heat, Cold, and Climatic Determinism in China’s Urban Epidemics’ by Chee et al. (2024) extends the definition of thermal governance to public health interventions by Traditional Chinese Medicine (TCM) as an official state medicine of the People’s Republic of China. While ‘heat’ is defined simply by temperature in biomedicine, many traditional medical systems around the world, including Chinese medicine and Ayurveda, consider it a more fundamental component of bodily existence, and not subject to instrumental definition. TCM has been supported and subsidised as a state medicine in China since the 1950s, but the recent SARS and COVID-19 viruses elevated its status as a medicine of emergency, and thus brought medical theories around the binaries of hot/cold (and damp/dry) into the diagnosis and treatment of urban epidemics. TMC diagnostics are also meteorological, making connections between the state of the patient and that of the weather and even climate. On the other hand, climate-based diagnoses by state-employed elite physicians – which are not always in agreement – are just as often ignored or misunderstood by urban consumers, who amid epidemics rush to protect themselves with ‘heat-clearing’ off-the-shelf formulas regardless of official advice. The authors suggest that ignoring the cultural subtleties of how heat (and cold) are interpreted beyond simply temperature readings, misses important discussions and actions involving (and influencing) the health of large segments of Asia’s urban population.

Making heat visible

Unlike many other manifestations of the current climate crisis, such as rising ocean levels, swelling rivers, more ferocious storms and wildfires and increases in disease-bearing insect populations, heat is still considered in many quarters to be a problem for individuals to solve, a matter of ‘personal protection’, secured through seeking shade, purchasing devices (fans or air conditioners), remaining hydrated, eating the right food, taking the right medications, wearing the proper clothing, etc. Urban planning and civil engineering initiatives taken to mitigate the effects of climate change on urban infrastructure do not usually start with protecting populations from solar radiation and hot temperatures, and often never get around to it. Architects are becoming more sensitive to protecting the inhabitants of the buildings they design, and yet architecture, as opposed to mere building, is a luxury for the middle and upper classes and can even come at the expense of the most vulnerable. Urban planners are beginning to recognise the necessity of mitigating UHI effects through greening and other measures, and yet long-standing development paradigms are slow to change, as is existing urban fabric. The result is too often vulnerable urban populations doing their best with inadequate resources, and increasing demographic gaps in thermal control, comfort and health.

This issue argues that urban heat is not just a matter between individuals and the sun, but an element baked into the way cities are planned, built and managed. Thermal control, governance and health are a continuum in urban life, and always have been, whether the source of greatest danger was heat or cold. In the cities of the Global North, including parts of northern Asia, the provision of winter fuel, clothing and shelter has always been of the greatest necessity, though unequally distributed (Plueckhahn, 2022), while mitigating against summer heat has until recently been more option than prerogative. For the historically hot Asian cities we have discussed, heat and humidity have always been primary factors in urban life, though never to the extent they are today. In nearly all places, however, the social and political factors that shape the thermal environment of cities have too often been masked, or at least under-analysed, and heat has ranked relatively low on the list of urban vulnerabilities. This issue strives to render those factors more visible and make heat in all its nuances a higher priority in histories, ethnographies and other accounts of modern urban life.