Urban Heat Island in Bengaluru: Built-up Growth and Temperature Trends

Bangalore, once renowned as India’s “Garden City”, has transformed into a “Silicon Valley” metropolis over the past five decades, experiencing profound environmental changes. This study investigated the direct correlation between the city’s extensive built-up area expansion and rising temperatures, drawing upon comprehensive literature and climate data. The analysis revealed a dramatic 1055% increase in built-up areas, from 7.97% in 1973 to 93.3% in 2023.Concurrently, vegetation cover has plummeted by 88% (from 68.27% to approximately 6%), and water bodies have decreased by 79%. These significant land-use alterations have led to notable thermal shifts in the region’s climate. Land Surface Temperatures (LST) increased by 7.9°C, from 33.08°C in 1992 to 41°C in 2017, while average air temperatures rose by 0.23°C per decade since 1975.The urban heat island (UHI) effect was pronounced, with an average annual nighttime surface UHI of 0.99 °C. A strong inverse relationship between vegetation cover and LST (R = -0.74 in dry seasons, -0.34 in wet seasons) confirms the critical role of green spaces in urban areas. This evidence unequivocally attributes the escalating UHI effect to the rapid, unplanned urban growth of Bangalore, underscoring the urgent need for sustainable urban planning.