The Summer of Heat Islands
Photo: Eddy Pellegrino from Pixabay
Indian urban centres are getting hotter every year due to the heat island effect. With millions of lives at stake, urgent city-planning measures are needed across the country to mitigate the incoming crisis.
Delhi becomes a dystopian nightmare every summer, but crossing the 50-degrees Celsius mark was something that even the most dyed-in-the-wool Delhite could hardly foresee in their lifetime. This year that grand half-century mark was breached; the New Delhi suburb of Mungeshpur hit a national all-time high of 52.3 degrees Celsius on May 29.
Later, it turned out that the Rubicon hadn’t actually been passed, and, instead the electronic instruments set up to record the temperature had miscalculated on account of malfunction, caused by… what else…? but excessive heat! The real temperature was alleged to be 49.9 degrees Celsius (much like Milkha Singh or PT Usha missing a medal by a whisker!), conveniently stopping short of 50 so as not to necessitate emergency measures.
The blunt truth is that Delhi, and other major urban centres, around the breadth of India are getting hotter every year. This may be occurring on account of what has been called the Urban Heat Island Effect. This effect describes a phenomenon of an urban built-up area being warmer than the rural area it is contiguous to. The variation in temperature between an urban and rural area is because many surfaces across urban centres are more amenable to absorbing as well as retaining heat.
The surfaces that dominate a cityscape comprise dark-coloured materials like asphalt, concrete, steel, and brick. They are excellent at absorbing light and converting it into heat. Rural areas on the other hand have a larger presence of greenery-grass, trees, shrubs, standing crops and so on which suck water through their roots and ultimately release it via their leaves by way of transpiration, which functions much like air-conditioning does inside our homes, and cools the environment somewhat.
This effect describes a phenomenon of an urban built-up area being warmer than the rural area it is contiguous to. The variation in temperature between an urban and rural area is because many surfaces across urban centres are more amenable to absorbing as well as retaining heat.
According to a study by IIT, Kharagpur, there is potential for major health concerns for the population residing in major Indian urban centres, where the summer heat wave exacerbates the existing problem of air pollution. Researchers studied the temperature difference that existed between urban and nearby rural land surfaces through the seasons across 44 major cities from 2001-2017. They discovered evidence to suggest that the mean daytime temperature of surface urban heat (UHI Intensity) increased by up to 2 degrees Celsius in the case of most cities, as extrapolated from satellite temperature measurements during the monsoon and post-monsoon periods. There has been similar research elsewhere that has zeroed in on the fact that there has been a similar rise in daytime temperatures attributed to Delhi, Mumbai, Hyderabad, Chennai and Bangalore.
Urban heat islands are caused by a number of certain distinct factors. One: It is a function of using what are called low albedo materials, which alludes to the ratio of the reflected solar energy to the incident solar energy. It is impacted by how surfaces, coatings, materials, pavements and so on are arranged. Any urban surface containing low albedo will store more energy, leading to an enhancement of urban temperature, which in effect creates a micro-climate. Delhi attracts migrants in the hundreds of thousands every year in need of housing, leading to a mushrooming of apartment complexes wherever there is land available. The population explosion has given rise to an expansion in the road and flyover network in the city. All this frenetic construction activity has led to an enormous increase in low albedo surfaces, which have caused extreme heat surges every summer.
Two: City centres invariably witness greater human gathering on account of the amenities available there, leading to more carbon dioxide emission. These emissions help store heat leading to a concomitant rise in atmospheric temperature. Delhi, for instance, comprises many city centres that see a concentration of human activity and hence higher temperatures. Heavily built-up areas like Connaught Place and Sitaram Bazar are hotter than the wooded Ridge Area, the Jawaharlal Nehru University campus, and Vasant Kunj.
Three: The enhanced use of air-conditioning in summer to cool down buildings inside only ends up warming up the outside environment, with the release of heat, and thereby, contributing to a rise in temperature in urban centres.
Four: Rampant deforestation in urban areas to make way for more infrastructure leads to less efficient cooling of the environment, again contributing to a rise in urban temperature. A prime example of this is the recent case of the Supreme Court coming down heavily on Delhi Development Authority for illegally allowing the felling of 1100 trees in the Ridge area.
Five: A great density of tall buildings in urban city centres creates what is called the ‘urban canopy’. This phenomenon traps the heat reflected by a building among the taller buildings nearby, thereby heating the environment. Most of the recent growth in housing in Delhi has been vertical leading to much greater density of tall buildings than ever before. Private real estate bigwigs like DLF, Godrej, Parsvnath are dramatically altering the skyline of city that wasn’t exactly known for its high-rise structures
Lastly: A greater density of buildings in urban areas effectively reduces wind velocity, which in turn leads to less cooling by way of convention as the trapped heat can no longer be effectively carried away by the wind.
India is urbanizing rapidly as a consequence of its economic growth. The growth is necessary to lift vast masses of its people out of poverty, and is a process that cannot be halted or even stalled, for providing for its people should be the priority of any nation. However, given that unbridled climate change can ultimately derail the very economic growth that one seeks, it is important that steps be taken to mitigate the impact of phenomena like urban heat islands.
Among the measures that Indian cities and major urban centres could adopt include using paving that is lighter in colour. The roads, on the other hand, could be porous green instead of the current gray and black. The process of heat reflection could aid in lowering the overall temperature. Furthermore, urban centres could explore the use of green roofs to bring down the temperature. According to some estimates, roofs comprise about a quarter of a city’s area, which means that making roofs green by growing vegetation on them can have a major salutary impact on the urban heat island effect. Green roofs not only do these absorb the heat and clean the air, but they also remove it from the environment by using heat energy to power their evapotranspiration process.
Growing shade trees (trees that are grown and valued for their ability to provide shade), increasing the number of water bodies and better urban planning are other important measures that need to be fast-tracked. Everybody from the government, social organizations and civil society members to architects, builders, town planners and citizens must step up to the plate and do everything required to ensure that we cool down our cities, towns, and urban centres. There are quite a few heartening examples of cities that took proactive measures like the ones described in this article to lower the temperature of their environs. The Dutch city of Arnhem found that the way that its roads were designed or constructed contributed to the heat island effect. Their solution comprised evaluating which roads were underutilized and replacing it with greenery. Furthermore, the city planted trees along bicycle paths and sidewalks, as well constructed parks that provided shade and ponds designed to help people and spaces to cool down
Several Indian urban centres have implemented what are known as Heat Action Plans or HAPs to mitigate the impact of intense heat wave. Nagpur, for example, has set aside heat wards to treat heatstroke patients, and advised builders to give breaks to construction workers on very hot days. Mumbai has mandated for outdoor events to be held in the early mornings before the mercury rises. A series of similar HAP measures across are being implemented across 23 Indian states.
There is need for more urgent action. The quickly changing climate will force us to learn to adapt. Millions of lives depend upon our decisions going forward, especially in developing countries like India situated in the tropics. Without appropriate measures, breaking past the 50-mark on the thermometer could soon become an unwelcome tradition every summer.
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Vipin Labroo is a content creator, author and PR consultant. A member of the Nonfiction Authors Association, he has years of corporate experience working with an eclectic range of clients, writing press releases, articles, blogs, white papers, research reports, website content, eBooks and so on across segments like technology, business & marketing, internet marketing, healthcare, fashion, real estate, travel and so on. You can find him on Twitter: @labroovipin and Instagram: @vipin_labroo.
