Wounds of heat – Chennai’s climate catastrophe and caste

Urban heat islands in Chennai

chennai urban heat island
Urban Heat Island effect is felt more in areas with less vegetative cover in Chennai. Pic: Faiz Binjai/Flickr (CC BY:SA 2.0)

Chennai is known for its brutal weather and amazing food. But with the consistent surge in heat, our everyday lives feel like we live in a microwave. We often read and hear a lot about climate change, but only truly recognize its impact when we step outside. We find ourselves exhausted and irritated while having to wait at traffic signals, while crossing the road, and while waiting for public transport. It’s during these moments that the reality of our changing environment hits us

The moment we are away from the bustling city we often sense a drop in temperature. This can even be felt in certain places in the city where green canopies or water bodies abound. This phenomenon is called Urban Heat Island (UHI) – which refers to areas in the city that are significantly hotter than the surrounding rural areas. 

UHIs are caused by factors such as dense construction where buildings and structures trap heat due to their insulating properties. Additionally, the continuous release of “waste heat” from various human activities, including transportation and industrial processes, contributes to UHIs. 

This brings us to the question, can the distribution of this heat be disproportionate to the demographics? 

The heat is unevenly distributed in the city and one factor is majorly linked to demographic determinants such as caste and income. The marginalized or people with less and no resources are highly exposed to urban heat and its detrimental damage in Chennai. 


Read more: Why Chennai needs to put its ‘heat action plan’ to practice right away


Unequal spaces and the impact of heat in Chennai

Claiming Indian villages to be a ‘sink of localism, a den of ignorance, narrow-mindedness and communalism’, B.R. Ambedkar urged Dalits to move away from lands practising regional segregation to urban spaces of anonymity and equality. Today, Ambedkar’s urban utopia is still a distant dream. 

Chennai has the highest share of SC/ST population among India’s major cities, with a remarkable 17% of its population belonging to vulnerable communities.  The inherent and evolving spatial segregation within cities is like a festering wound, endangering the vulnerable and marginalized populations compared to the rest of the residents living in adjacent neighbourhoods. They are usually densely populated and live on the margins of land. Consequently, they suffer from diminished vegetative cover, elevated temperatures, and a higher prevalence of residents with lower incomes, setting them apart from other areas within the city. 

Excessive heat poses a significant financial challenge, particularly for low-income households. Many struggle to cover energy bills or find themselves unable to afford cooling their homes, primarily due to cost-related concerns. These households often reside in less energy-efficient housing, further exacerbating their cooling expenses. 

According to the Chennai Climate Action Plan, 53% of households rely on external sources for drinking water, highlighting a pressing issue of water scarcity. Additionally, 27% of slum dwellings employ asbestos sheets as roofing materials, significantly higher than the 8.9% found in all Chennai houses. This places marginalized residents at increased vulnerability to heat stress, as these materials contribute to prolonged daytime heating and slower nighttime cooling. Furthermore, many slum households have limited or no access to cooling equipment, potentially exacerbating heat-related health risks and even increasing the likelihood of heat-related fires.

land surface temperature map in chennai
Land surface temperature map of Chennai. Source: Chennai Climate Action Plan

The map highlights significant temperature variations within the city. The airport area, influenced by air traffic and pollution, records the highest temperature at 43.3°C. The Perungudi dump yard follows closely at 42.6°C, it’s important to recognize that heat generation in landfills is a natural occurrence.

Additionally, this area houses a significant number of marginalized communities and slums, such as Kallukuttai. It is crucial to acknowledge that the city’s cleaners bear the consequences of waste generated by affluent sections of society, who have the purchasing power to produce waste, ultimately contributing to the heat.

In stark contrast, Guindy National Park records the lowest temperatures at 23°C. This area encompasses affluent neighbourhoods like Adyar and Velachery, which enjoy relatively better living conditions and access to cooler resources.

Some inspiring initiatives to help tackle heat impact in Chennai

Some of the ways in which such inequalities are addressed are through strategies that have been adopted by other cities and ones already being piloted in Chennai.

We need to focus on making reduction strategies renters friendly.  In the cities of Ahmedabad and Bhopal, Mahila Housing Sewa Trust (MHT) roof projects have showcased their expertise in utilizing modular roofs to effectively reduce temperatures by 5-6°C. They emphasize that even simple measures like painting roofs white and making them reflective can contribute to a significant 2°C drop in temperature. 

Furthermore, MHT’s innovative approach extends to strategies such as growing creepers on walls and establishing rooftop kitchen gardens to enhance home cooling.

The Chennai Urban Farming Initiative (CUFI), led by the Chennai Resilience Centre (CRC), is dedicated to bolstering Chennai’s resilience to climate change and supporting self-reliant urban communities, with a focus on the disadvantaged. CRC has partnered with Earthonomic Engineers to investigate the heat mitigation effects of a terrace garden at the Anbagam Homeless Shelter in Otteri, West Chennai.

Data collected and analysed between April 1st to June 6th, 2022, has unveiled striking insights. On average, during the sunlit hours from 6 am to 6 pm, the area beneath the rooftop garden enjoys a remarkable 2-3°C reduction in temperature compared to the space beneath the exposed terrace, with peak differences reaching an impressive 7°C. This research underscores the tangible benefits of urban gardening in mitigating heat and enhancing comfort.


Read more: Summers are getting worse in Chennai. How can we build cooler homes?


To bridge, you acknowledge

The September 2022 Chennai Climate Change Action Plan, highlights the persistent challenges posed by the UHI effect on vulnerable communities. Regrettably, it reinforces the notion of slum rehabilitation and fails to acknowledge the urban geometry hindering green that’s been gauged by real estate actors in the city.  This approach not only disregards human rights but also compromises sustainability by relocating people to resource-poor areas without a viable livelihood plan, exacerbating the situation.

In order to plug in the gap and garner green it’s important to include the primary stakeholders, the marginalized residents in the decision-making process – not an external representative or an ideological leader but the community people. The recent Caste survey of Bihar is historic, likewise charting a state-level caste census survey is likely to table a fresh and updated data set for policymaking. 

The equitable urban dream is a farfetched goal, but the first step is to acknowledge the divide in order to design need-based solutions that shield against the scorching wounds of heat and health. It is time to quality test “Vandharai Vaazha Vaikum Chennai”.

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About Anushri Muthusamy 1 Article
Anushri works as a public policy analyst at Apogee Research Forum. She writes and researches on gender, society, climate and inequality.