In the heart of India, Kolkata, a bustling metropolis home to over 15 million residents, is grappling with a silent yet potent challenge: the relentless rise of urban heat islands. A recent study, published in the journal Discover Environment (translated from Bengali as ‘Discover Environment’), delves into the intricate dance between land use changes and land surface temperatures (LST) in the Tollygunge-Panchannagram (TP) basin of Kolkata. The research, led by Chiranjit Singha from the International Center for Agricultural Research in the Dry Areas (ICARDA), offers a compelling narrative that resonates with urban planners, energy sector professionals, and environmentalists alike.
Singha and his team harnessed the power of Google Earth Engine (GEE) to analyze Landsat data from 2000, 2010, and 2020, painting a vivid picture of the city’s evolving landscape. Their findings are stark: the maximum LST in the TP basin has surged from 36.15°C in 2000 to a sweltering 47.65°C in 2020. “The strong positive association between the Normalized Difference Built-up Index (NDBI) and LST is a clear indicator of the urban heat island effect,” Singha explains. “As built-up areas expand, so do the temperatures, particularly in the western and northwestern sectors of the basin.”
The study employs the Methods of Land Use Change Evaluation (MOLUSCE) plug-in in QGIS, which integrates Artificial Neural Networks with Cellular Automata (CA-ANN), to project LST for 2030. The results are sobering: built-up areas are expected to expand by another 8.1% by 2030, leading to further reductions in vegetation, open spaces, and water bodies. “Rapid urbanization is significantly altering the city’s microclimate,” Singha notes, “and this has profound implications for the energy sector.”
As cities like Kolkata continue to grow, the demand for cooling is set to skyrocket. Air conditioning units, already a staple in many homes and offices, will become even more ubiquitous, placing a substantial strain on energy grids. The commercial impacts are clear: energy providers must prepare for increased demand, while businesses grapple with the costs of keeping their premises cool. Moreover, the reduced extent of water-related land cover could exacerbate water scarcity issues, further complicating the city’s water management strategies.
This research underscores the urgent need for sustainable Urban Heat Island (UHI) management strategies. “Increased green cover and water body restoration are not just environmental imperatives,” Singha asserts, “they are also sound economic strategies that can help mitigate the commercial impacts of rising temperatures.”
The study’s findings are a clarion call for action, highlighting the need for integrated approaches that balance urban development with environmental sustainability. As cities around the world grapple with similar challenges, the insights gleaned from Kolkata’s experience offer valuable lessons for urban planners, energy sector professionals, and policymakers alike. The path forward is clear: to build resilient, sustainable cities, we must harness the power of technology and innovation, while also nurturing the natural environments that sustain us.