Bengaluru is experiencing an unprecedented rise in temperatures, primarily due to the Urban Heat Island (UHI) effect. This phenomenon, exacerbated by infrastructure changes, is causing discomfort for residents. The city’s temperature reached 35.4°C in March 2025, signalling a potential record-breaking April. The UHI effect retains heat in urban areas, preventing its dissipation. This has led to temperatures in UHI zones being 3 to 5 degrees higher than their surroundings.
About Urban Heat Islands
Urban Heat Islands occur when urban areas become warmer than their rural surroundings. This is due to human activities and infrastructure. The construction of heat-absorbing materials, such as concrete and glass, contributes greatly to this effect. The loss of green cover further intensifies the situation, leading to higher local temperatures.
Impact of Infrastructure Development
Bengaluru’s infrastructure projects, like the Namma Metro Phase 3, are set to remove over 11,000 trees. This loss of greenery is critical, as trees play a vital role in cooling urban areas. The compensatory plantation efforts have been questioned for their effectiveness and location. Environmental activists argue that new trees should be planted within the city rather than in distant locations.
Heat Wave Action Plan
The Karnataka State Heat Wave Action Plan 2023-24 aims to address the rising temperatures. It includes creating a heat wave risk map and developing mitigation strategies. Proposed measures involve establishing vertical gardens and small parks to help lower temperatures in hot spots. The plan also emphasises collaboration with research institutions for effective urban planning.
Decline of Green Cover
Bengaluru has seen a drastic reduction in its green cover. From 68.2% in 1973, it plummeted to just 6.02% by 2025. This decline is linked to increased paved surfaces, which now account for 87.64% of the landscape. The lack of vegetation hampers groundwater recharge and contributes to rising temperatures.
Environmental and Health Implications
The UHI effect poses serious health risks, particularly for vulnerable populations. Increased temperatures can lead to heat-related illnesses, including heat strokes and dehydration. Additionally, buildings with glass façades contribute to higher electricity consumption, further exacerbating global warming.
Solutions and Future Directions
Experts advocate for a holistic approach to urban forestry. This includes integrating green spaces into city planning and maintaining existing trees. The World Health Organisation recommends a minimum of 9 square metres of green space per person, denoting the need for more urban greenery.
Questions for UPSC:
- Discuss the implications of the Urban Heat Island effect on urban planning and public health.
- Critically examine the relationship between urban infrastructure development and environmental degradation in metropolitan cities.
- Explain the significance of green cover in urban areas and its impact on temperature regulation.
- With suitable examples, discuss the role of government policies in mitigating urban heat effects in rapidly developing cities.
Answer Hints:
1. Discuss the implications of the Urban Heat Island effect on urban planning and public health.
- UHI leads to higher local temperatures, affecting thermal comfort and increasing energy demand.
- Higher temperatures contribute to heat-related illnesses, especially among vulnerable populations like the elderly and children.
- Urban planning must incorporate green spaces to mitigate UHI effects and enhance public health outcomes.
- Increased heat can strain healthcare systems and lead to higher mortality rates during heatwaves.
- Effective urban design can integrate cooling measures, such as parks and green roofs, to combat UHI.
2. Critically examine the relationship between urban infrastructure development and environmental degradation in metropolitan cities.
- Infrastructure projects often result in tree loss, reducing green cover and exacerbating UHI effects.
- Urban sprawl leads to increased paved surfaces, which contribute to heat retention and decreased groundwater recharge.
- The prioritization of development over environmental concerns often results in long-term ecological damage.
- Compensatory plantation efforts are frequently ineffective if trees are planted far from the areas affected.
- Infrastructure planning must balance development needs with environmental sustainability to prevent degradation.
3. Explain the significance of green cover in urban areas and its impact on temperature regulation.
- Green cover plays important role in cooling urban environments through shade and evapotranspiration.
- Vegetation helps in groundwater recharge, which is essential for maintaining local water cycles.
- Adequate green spaces can lower urban temperatures by 2-3 degrees, improving overall climate resilience.
- Green cover enhances biodiversity and provides habitats for urban wildlife, contributing to ecological balance.
- World Health Organization guidelines recommend sufficient urban green space to support public health and well-being.
4. With suitable examples, discuss the role of government policies in mitigating urban heat effects in rapidly developing cities.
- Policies like the Karnataka State Heat Wave Action Plan aim to create heat risk maps and mitigation strategies.
- Government initiatives can promote the development of vertical gardens and green roofs to combat UHI.
- Examples include the commitment to plant 50,000 saplings in Bengaluru, addressing tree loss from infrastructure projects.
- Regulations can enforce the integration of green spaces in urban planning and development processes.
- Collaboration with research institutions can enhance data-driven strategies for effective urban heat management.
