Bengaluru's Rising Temperatures and UHI

A recent study focusing on Bengaluru has highlighted significant changes in the city's climate, particularly regarding the increase in urban temperatures due to extensive urbanization. The research, titled "Urban heat island linkages with the landscape morphology," was published in the journal Nature on July 8, 2025, conducted by researchers T.V. Ramachandra, Rajesh Singh Rana, S. Vinay, and Bharath H. Aithal.

Key Findings:

• Temperature Rise: Bengaluru has experienced a severe increase in temperature, notably from an average of 16°C in May during the 1970s to a projected 34°C in May 2025. These increases reflect broader climatic changes, with the city experiencing more days of above-average temperatures when compared to historical data from 1991-2020.

• Urban Expansion: Between 1973 and 2025, the urban built-up area in Bengaluru surged by an alarming 1,078%, growing from 7.97% to 87.64% of the city's total area. As a result, only 168.93 sq. km remains under favorable ecological conditions according to the Urban Thermal Field Variance Index (UTFVI).

• Impact on Landscape: The urban landscape has significantly impacted green cover and water bodies, with vegetation cover declining by 88% and water bodies by 79%. The study attributes this transformation to extensive urban sprawl and the conversion of agricultural land into paved surfaces.

• Urban Heat Island Effect: An "UHI archipelago" has been identified in the eastern and northern parts of the city, where localized heat islands contribute to elevated temperatures. The study noted that the alteration of the landscape resulted in a shift from natural porous surfaces, such as vegetation and lakes, to hardened surfaces like buildings and roads.

• Temporal Analysis: Temperature data from the India Meteorological Department indicate a consistent upward trend, corresponding with urbanization and the reduction of natural landscapes. The study utilized temporal remote sensing data to assess environmental conditions.

• Policy Recommendations: To mitigate the effects of urban heat islands, the study emphasizes integrating more green spaces into urban development plans, including:

  • Establishing mini forests of native species in each ward.
  • Maintaining 30% open spaces with green cover in urban plots.
  • Connecting fragmented tree patches to support ecosystem health.
  • Rejuvenating existing water bodies to aid groundwater recharge and rainwater retention.

• Urban Development Phases: Analysts observed that the urban trajectory of Bengaluru can be divided into distinct phases:

  • 1973-1992: Growth of 1% annually driven by the establishment of nationalized public sector industries and the burgeoning IT sector amid a liberalizing economy.
  • Post-2002: Growth rates increased to 2.01% due to the rise of private industries and Special Economic Zones (SEZs).
  • 2012-2021: Accelerated urban growth with a 3% increase driven by the IT sector.
  • Post-2021: Urbanization has slowed to 0.5% but continues to extend beyond the Bruhat Bengaluru Mahanagara Palike (BBMP), engulfing adjacent agrarian landscapes.

Conclusion:

The findings of this study reflect the urgent need for strategic urban planning and policy action to address the rising temperatures resulting from rapid urbanization in Bengaluru. The Chief Town Planning Officer has shown a positive inclination towards incorporating these research outcomes into the Revised Master Plan 2031.

Important Points:

• Study published in Nature highlights increased temperatures in Bengaluru.
• Urban area increased by 1,078% from 1973 to 2025.
• May temperatures projected to rise to 34°C by 2025.
• 88% decline in vegetation cover and 79% in water bodies noted.
• Recommendations include expanding and protecting green spaces and rejuvenating water bodies.
• Urban growth phases highlight the relationship between economic factors and land use changes.