THE CONTEXT: On May 29, Delhi’s Mungeshpur automatic weather station recorded an unprecedented temperature of 52.9 degrees Celsius, which provoked widespread disbelief. Although this anomaly was later attributed to a sensor error, it highlighted a broader issue of the consistent long-term rise in the summer heat index in Delhi. This trend, characterized by increasing air temperature, relative humidity, and land surface temperature, signals a new normal of growing heat stress in urban centers.
THE ISSUES:
- Urban Heat Island Effect: The expansion of built-up areas in Delhi has increased heat-trapping concrete surfaces. Delhi’s built-up area grew from 31.4% in 2003 to 38.2% in 2022. This effect is exacerbated by the reduction in green spaces and water bodies, which traditionally help cool urban environments. Delhi lost half of its surface water between 1999 and 2021.
- Inadequate Green Cover: Most urban development projects fail to meet the World Health Organization’s proposed nine sq m of green space per individual. Delhi has only 10.41 sq m per capita, insufficient to mitigate urban heat.
- Increased Relative Humidity: Rising humidity levels, especially during the monsoon season, have significantly increased the heat index, making the weather feel hotter than the actual temperature. This combination of high heat and humidity limits the body’s ability to cool itself through sweating, leading to increased thermal discomfort and health risks.
- Disappearing Water Bodies: The loss of water bodies, which can reduce ambient temperatures by 3-8 degrees in a microclimate, further exacerbates the heat problem. Delhi’s significant reduction in surface water contributes to higher temperatures.
- Additional Heat Sources: Heat from vehicle tailpipes, industrial processes, and building air conditioning adds to the city’s overall heat load. However, no explicit policy action is taken to address these heat generators.
- Poor Communities: Urban heat maps show that heat hotspots often overlap with areas where poor people live. These communities are more vulnerable due to underlying health conditions and lack of access to cooling resources.
- Elderly and Children: The elderly and children are particularly susceptible to heat stress. The ‘2023 Lancet Countdown and Health and Climate Change report predicts a 370% increase in heat-related deaths among the elderly by mid-century.
THE WAY FORWARD:
- Increase Urban Green Spaces: Expand and maintain urban green spaces to provide shade, reduce temperatures, and improve air quality. Singapore has successfully cooled down parts of its metropolitan areas by planting over 7 million trees and creating more than 300 parks and gardens. This has helped mitigate the urban heat island effect and improve the city’s livability. Green spaces can significantly reduce land surface temperatures (LST). For example, areas shaded by dense foliage can have an LST of 29.7°C compared to over 40°C in unshaded areas.
- Implement Cool Roofs and Pavements: Adopt cool roofs and pavements that reflect more sunlight and absorb less heat. Los Angeles, USA, has tested cool pavement projects since 2017, reducing surface temperatures by up to 11°C (51.8°F). Since 2009, New York City has installed more than 10 million square feet of green and cool roofs, reducing its annual greenhouse gas emissions by 16,000 metric tons.
- Enhance Water-Sensitive Urban Design (WSUD): Incorporate water bodies and water-sensitive urban design to cool urban microclimates and improve thermal comfort. Adelaide, Australia’s WSUD features and irrigation have been shown to reduce surface temperatures by up to 1.8°C and improve human thermal comfort in urban environments. Water bodies can reduce ambient temperatures by 3-8 degrees in a microclimate, providing significant cooling benefits.
- Promote the Use of Electric Vehicles (EVs): Encourage the adoption of electric vehicles to reduce heat emissions from traditional internal combustion engines. In Hong Kong, a study found that replacing conventional cars with electric vehicles could reduce the intensity of urban heat island by approximately 1°C.
- Develop Comprehensive Heat Action Plans: Create and enforce comprehensive heat action plans that include long-term systemic changes to reduce heat risks. Chicago, USA, has established over 120 cooling centers and implemented various heat management strategies to protect residents during heat emergencies. Effective heat action plans should include measures such as increasing green cover, implementing cool roofs and pavements, enhancing water-sensitive urban design, and promoting the use of electric vehicles.
THE CONCLUSION:
The unprecedented temperature reading at Delhi’s Mungeshpur station underscores the urgent need for robust, long-term strategies to manage urban heat stress. Comprehensive heat action plans, supported by legal mandates and adequate funding, are essential to mitigate the impacts of rising temperatures and ensure the well-being of urban populations. Cooling actions must be prioritized to improve adaptive thermal comfort and prevent the entrenchment of urban heat traps in a changing climate.
UPSC PAST YEAR QUESTIONS:
Q.1 Discuss the various social problems that originated from the speedy urbanization process in India. 2013
Q.2 Identify the causes of the formation of heat islands in the urban habitat of the world. 2013
Q.3 Discuss global warming and its effects on the global climate. In light of the Kyoto Protocol, 1997, explain the control measures to bring down the level of greenhouse gases that cause global warming. 2020
MAINS PRACTICE QUESTION:
Q.1 Delhi’s recent unprecedented heat peak highlights a broader trend of rising summer heat indices in urban centers. Discuss the factors contributing to this phenomenon and suggest comprehensive measures to mitigate the urban heat island effect and improve city thermal comfort.
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