Bengaluru, once celebrated for its mild and pleasant climate, is now witnessing a dramatic transformation into a city of intensifying heat zones, according to a recent study by the Indian Institute of Science (IISc). The research highlights the emergence of nearly 200 “heat archipelagos”—clusters of urban heat islands spread across the city—signaling a serious decline in its environmental balance.
The study explains that these heat archipelagos consist of 50–70 extreme heat pockets each, formed due to rapid and unplanned urban expansion. Over the decades, Bengaluru has seen a steep rise in built-up areas, which increased from just 8% in 1973 to a staggering 87.6% in 2025, leaving very little room for natural cooling systems like forests, lakes, and open green spaces.
As a result, nearly 545.2 sq km of the city’s total 740 sq km area is now classified under “unfavourable ecological conditions.” In many parts of the city, land surface temperatures are reported to peak at 48°C, while average summer temperatures hover around 38.6°C, making daily life increasingly difficult for residents.
Experts attribute this worsening condition primarily to rapid urbanization, loss of vegetation, and shrinking water bodies. Concrete structures, asphalt roads, and high-density construction trap heat during the day and release it slowly at night, preventing the city from cooling down effectively. This phenomenon is widely known as the Urban Heat Island (UHI) effect.
Despite the alarming trend, the study identifies a few remaining cooling zones within Bengaluru. Areas such as Cubbon Park, Lalbagh Botanical Garden, and the IISc campus continue to provide localized relief due to their dense tree cover and better ecological balance. These pockets act as natural heat buffers, reducing surrounding temperatures significantly.
Researchers have stressed the urgent need for corrective measures, recommending that the city maintain at least 30% green cover at the plot level. They have also urged authorities to incorporate stronger environmental safeguards into the upcoming Master Plan 2031, emphasizing sustainable urban planning as a necessity rather than an option.
The findings come at a time when Bengaluru is already grappling with rising temperatures and increasingly frequent heat-related concerns. Environmental experts warn that without immediate intervention, the city’s liveability could deteriorate further, especially as climate change continues to intensify extreme weather patterns.
The IISc study serves as a critical reminder that Bengaluru’s identity as a “garden city” is under threat. It underscores the need for a balanced approach to development—one that prioritizes green infrastructure alongside urban growth to restore ecological stability and reduce heat stress for millions of residents.
