Introduction
The phenomenon of Urban Heat Islands (UHI) has emerged as a critical concern for urban governance in India. As metropolitan areas expand, the transition from natural landscapes to dense, heat-absorbing concrete environments has disrupted local micro-climates. Understanding the mechanics of UHI and the policy frameworks aimed at urban cooling is essential for addressing the environmental challenges of rapid urbanisation.
Why in News?
- Escalating temperatures and recurrent heatwaves across Indian cities have placed urban planning and building materials under scrutiny.
- Experts are pushing for a policy shift to mandate heat-reflective surfaces and mandatory green cover in urban building codes to counter rising thermal stress in metropolitan regions.
Static Link
- The Urban Heat Island (UHI) effect is a core concept in Urban Geography and Environmental Science.
- It occurs when urban areas experience higher temperatures than surrounding rural areas due to human-induced land-use changes.
- UPSC often tests the conceptual link between surface albedo, thermal mass of materials (concrete/asphalt), and the reduction of urban vegetation, which together trap heat and prevent night-time cooling.
Institutional Link
- Ministry of Housing and Urban Affairs (MoHUA): Frames urban policies like the Smart Cities Mission and Model Building Bye-Laws.
- National Disaster Management Authority (NDMA): Coordinates and monitors heatwave management at the national level. Heatwaves are a notified disaster in India.
- State Municipal Corporations: Responsible for the on-ground enforcement of building regulations and urban planning.
Core Prelims Facts
- UHI can lead to a temperature difference of 5 to 10 degrees Celsius between city centres and rural peripheries.
- Thermal Mass: Concrete and asphalt act as thermal reservoirs, absorbing heat during the day and releasing it slowly at night.
- Evapotranspiration: The natural cooling process provided by vegetation and water bodies, which is lost during rapid concretisation.
- Albedo Effect: Increasing the reflectivity of surfaces (e.g., cool roofs) can significantly reduce solar absorption.
Important Terms and Concepts
- Urban Heat Island (UHI): A metropolitan area that is significantly warmer than its surrounding rural areas.
- Blue-Green Infrastructure: An integrated approach using water bodies (blue) and green spaces (green) to provide natural cooling.
- Thermal Mass: The ability of a material to absorb, store, and release heat.
Bodies / Organisations / Institutions
- National Disaster Management Authority (NDMA): An apex body for disaster management, crucial for heatwave action plans.
Schemes / Laws / Reports / Conventions
- India Cooling Action Plan (ICAP): A government framework aimed at reducing the cooling demand across various sectors of the economy.
- Smart Cities Mission: Focuses on sustainable urban infrastructure, including climate-resilient designs.
- Heatwave Action Plans: State-level policy frameworks designed to mitigate heat stress.
Possible UPSC Prelims Traps
- Misattributing the mandate: Assuming the Ministry of Environment is solely responsible for urban building codes (actually, it is MoHUA).
- Conceptual Trap: Thinking UHI only occurs in desert or tropical regions (it is a global phenomenon observed in all high-density urban areas).
- Authority Trap: Confusing the role of the NDMA (national level guidance) with the role of State Disaster Management Authorities (implementation).
- Absolute Word Trap: Believing that 'cool roofs' are the only solution; it is a multi-faceted approach involving green cover and architectural design.
One-Minute Revision Notes
- UHI is caused by high thermal mass (concrete) and loss of vegetation.
- Heatwave is a notified national disaster managed by NDMA.
- The India Cooling Action Plan (ICAP) addresses sectoral cooling demands.
- Mitigation strategies include reflective painting (albedo), increasing green canopy, and preserving urban wetlands.
Practice MCQ for Prelims
1. Consider the following statements regarding the Urban Heat Island (UHI) effect:
1. It is primarily caused by the use of high thermal mass materials like concrete and asphalt.
2. It occurs only during the daytime when solar radiation is at its peak.
3. The National Disaster Management Authority (NDMA) considers heatwaves a notified disaster.
Which of the statements given above are correct?
A) 1 and 2 only
B) 2 and 3 only
C) 1 and 3 only
D) 1, 2 and 3
Answer: C
Explanation: Statement 2 is incorrect because UHI effects persist into the night, as concrete releases stored heat long after sunset. Statements 1 and 3 are correct.
Original Article: https://www.thehindu.com/opinion/editorial/concrete-fever-on-india-and-heat-management/article71038035.ece
Full Current Affairs Analysis: https://iasment.com/urban-heat-resilience-and-sustainable-city-planning-in-india-mains-specific/