India’s hill states need sustainable cooling solutions to beat warming
A large number of Indian cities experienced scorching heat over the past week. As per Indian Meteorological Department (IMD), approximately 70 per cent of India experienced a maximum temperature between 40 and 46°C. According to an article published in Down To Earth on April 20, 2023, India has witnessed a 34 per cent rise in heat-related mortalities in 2013-2022 from the previous decade (2003-2012).
While such high temperatures are normal for some states, the Himalayan region saw the worst levels of mercury. The states in the region have witnessed moderate (0-4°C) to high (4-6°C) departures from the normal maximum temperatures in the past week.
For instance, Karsingsa, Itanagar, Anni, Passighat and Namsai in Arunachal Pradesh recorded a 3-5°C departure from the normal on May 23, 2024, according to IMD. At the same time, Ladakh, Jammu and Kashmir, Sikkim, Nagaland, Mizoram, Manipur, Tripura and Meghalaya recorded a 1-4°C departure from the normal.
The story does not end here; the IMD forecast on May 25 suggests that a 2-8°C departure will likely occur in Himachal Pradesh, Mizoram and parts of Ladakh in the coming days. This has several issues for people living in the hills.
First, people living in the hills have not experienced such high temperatures, so their tolerance to heat is limited. They are more susceptible to heat-related illnesses than someone living in the plains. Their exposure to heat is also high as most of the population works outdoors.
The preferable ambient temperature for humans ranges from 17-24°C, according to an analysis published in The Lancet Planetary Health. Prolonged exposure to temperatures beyond this can result in physiological stress, cardiovascular disease and other heat-related illnesses.
Secondly, hill states have not required active cooling infrastructure like fans and air conditioners. Increasing temperatures are forcing a switch to active cooling that would create a surge in electricity consumption and dent in people’s pockets.
If the electricity demand is not fulfilled via cleaner energy sources, this could lift the emission curve of the region. This means a vicious cycle awaits the Himalayan region wherein a warming environment means more anthropogenic heat due to cooling and more emissions.
Even India’s coastal belt was not spared by the rising mercury. On May 23 and 24, IMD recorded a 2-5°C departure from the normal across Medinipur in West Bengal and Puri in Odisha. Additionally, the entire west coast of India suffered from a 2-4°C departure from the normal on May 24.
The increase in temperature over the coasts is accompanied by high humidity, which increases the feel-like temperature. Such conditions create sultry weather, making it unsuitable for mental or physical work. This leads to a loss in productivity while inducing heat stress and thermal discomfort amongst the dwellers.
Most Indian cities fall under the plains, and the prevailing high temperatures here are leading to increased intensity of the Urban Heat Island (UHI) effect. On May 23, several cities in Rajasthan, Madhya Pradesh, Gujarat, Delhi, Punjab, Uttar Pradesh, Telangana, Andhra Pradesh, Maharashtra, Tamil Nadu, Jharkhand, Chhattisgarh, Odisha and West Bengal witnessed maximum temperatures above 40°C, according to IMD.
Hisar, Bhiwani and Mungeshpur in Haryana; parts of Delhi such as New Delhi and Najafgarh; Rajnandgaon in Chattisgarh; Mahabaleswar, Pune, Pimpri-Chinchwad in Maharashtra; Jamshedpur in Jharkhand; Baripada and Balasore in West Bengal; and a few other cities saw a 6-8°C departure from the normal temperatures.
IMD declared heatwaves to severe heatwaves in Rajasthan’s Churu; Jhansi, Mathura-Vrindavan and Agra in Uttar Pradesh; Khajuraho in Madhya Pradesh; and parts of Delhi (Pitampura, Narela and Pusa) on May 23. Further, cities are also experiencing high nighttime temperatures (approximately 5-6°C departure from normal minimum temperatures) due to UHI effect. This happens when the environment traps heat all day and releases it at night.
With such shifting temperature normals, cities need to both adapt and mitigate the impact of warming. This will require measures to cool down the environment. Increasing and improving green infrastructure is one such measure. It not only cools down the surroundings but also prevents flooding.
Green infrastructure includes green spaces and water bodies like parks, gardens, green belts, green roofs, ponds, lakes, etc. Green infrastructure restricts heat gain in urban areas via evapotranspiration and therefore plays a crucial role in regulating the micro-climate.
A 10 per cent increase in tree canopy cover can bring down afternoon temperatures by 1-1.5°C; active and passive water systems can lower the temperature by 3-8°C, according to the Ministry of Housing and Urban Affairs.
Further cooling materials for roofs and facades can reduce the indoor temperature by 2-5°C. Integrating such measures with master plans and building by-laws would bring a mandated implementation and enable cities to act for heat resilience and mitigation.