Kolkata climate adaptation

Located on the eastern banks of the Hooghly River, Kolkata – formerly Calcutta – is one of India’s most iconic cities, but also one of its most vulnerable to the impacts of climate change. In this comprehensive study, architect Gursharan Randhawa used ENVI-met’s advanced 3D modeling technology for her climate resilience project, examining microclimatic elements to develop effective strategies for mitigating heat stress and climate adaption.

Visualizing climate impacts in Kolkata

The effects of climate change are a tangible reality for the people of Kolkata, not just abstract concepts. From summer heat waves that exceed 45 degrees Celsius (113 degrees Fahrenheit) to worsening air quality from increased vehicle and industrial emissions, the city’s climate is undergoing profound changes. Situated low in the Ganges delta, Kolkata is also acutely vulnerable to rising sea levels, with projections of coastal flooding by the end of the century. Climate adaptation strategies are therefore more important than ever.

Thermal comfort strategies in Kolkata’s urban landscape

This intense heat poses serious health risks such as heat stroke, exhaustion, and dehydration, requiring urgent management action. An in-depth study of Kolkata’s neighborhoods, such as Howrah and Salt Lake, provided critical insights into current climatic conditions and potential heat stress mitigation strategies. Gursharan Randhawa, who led the project, worked with ENVI-met to conduct analyses and simulations that highlighted Kolkata’s vulnerabilities and identified key adaptation strategies. Kolkata’s struggle with extreme heat stress, exacerbated by high humidity, led Randhawa to highlight the effectiveness of nature-based solutions in addressing this challenge.

Using Physiologically Equivalent Temperature (PET) as a metric, the team demonstrated the resilience of the proposed Salt Lake neighborhood compared to densely populated Howrah. Nature-based interventions show immense potential, particularly in Salt Lake, where strategic placement of green spaces and optimized wind direction can reduce temperatures by 4-6°C during peak sunlight hours. Conversely, in Howrah, the introduction of urban green spaces yields a modest 2-4°C PET reduction, despite persistent high heat stress. A hypothetical scenario that Randhawa and her team envision for Salt Lake, with evenly distributed green spaces, promises even greater temperature reductions of up to 8°C during extreme heat events. Such interventions not only alleviate heat stress, but also improve Kolkata’s urban resilience and livability.

Older compact settlements, often humidity hotspots, require tailored strategies such as improved air circulation and water-absorbing facades to improve microclimatic conditions. Randhawa and her team’s targeted interventions hold promise for further reducing heat stress and promoting a more comfortable and sustainable urban environment for all Kolkata residents.