Megapolis Chennai: Prevent heat trap with a canopy of trees

CHENNAI: Ever wondered why some localities, especially ones where middle and lower income classes live as a densely populated neighbourhood, feel hotter than the ones that are posh? There is a reason, and it’s scientifically proven. But, we have a way out since a problem well stated is a problem half solved.

If you observe closely, many older independent houses within the core of Chennai are being razed down to give way for joint venture projects where builders construct smaller apartment buildings. Result: 10 families live in a space where one or two families lived. Furthermore, there is no space for trees.

Cramped-up taller buildings on a narrow street, lack of green cover added with more families releasing heat through ACs, cooking and others: a perfect recipe for urban heat island (UHI) effect.

UHIs are some pockets within a large city where temperature is higher than the city’s average temperature. Climate change experts, town planners and even governments acknowledge the issue and promote the idea of increasing the green cover and canopies to create a liveable micro-climate.

However, data show that Chennai is going backwards as it lost about 2.5 sqkm of green cover between 2021 and 2023. The Greater Chennai Corporation has 4.66% forest cover according to India State of Forest Report 2023. The report released in 2021, estimated 5.28% forest cover in Chennai.

A recent report released by the World Bank titled ‘Urban Heat in South Asia’ pointed out that outdoor temperatures and humidity levels are impacted by orientation of streets, sky view factor, and proximity to green space. As per the assessment, the area around Ranganathan Street – Rameshwaram Street (where streets are narrower) reached the highest temperature of 40-degree Celsius (around 5.8 higher than other locations) in the middle of the day. By 10.30 pm, it had cooled down by 5-degree Celsius while all the other locations had cooled down an additional 2-4 degrees.

Studies and our own experience teach us one thing: the city should create more parks with trees with broader canopies instead of creating mere green areas by planting ornamental trees. We also need to adopt greening strategies while building infrastructure like well-maintained hanging gardens on flyovers, mandatory space for avenue trees, and adherence to green building norms to cut emission of heat from households.