Tier-II cities in Eastern India contribute more urban heat than metros

The researchers underscored the importance of targeted urban planning and efforts to mitigate heat impacts, which could also address other urban issues like extreme rainfall, floods, and air pollution.
Image used for representaional purpose.
Image used for representaional purpose.Express | Debadatta Mallick

BHUBANESWAR: Even as India is gripped by a staggering heatwave, a latest study by researchers of the Indian Institute of Technology (IIT)-Bhubaneswar has revealed that urbanisation across the country has enhanced warming in cities, including, Bhubaneswar by 60 per cent.

The study ‘Urbanisation and Regional Climate Change-linked Warming of Indian Cities’, recently published in Nature, was conducted by associate professor of School of Earth (Ocean and Climate Sciences) V Vinoj of IIT-Bhubaneswar and research scholar Soumya Satyakanta Sethi.

The study pointed out that tier-II cities in eastern India showed stronger urbanisation-driven warming compared to larger metro cities like New Delhi and Mumbai.

It quoted another study which stated the contribution of urbanisation to night time land surface temperature warming was 70 per cent to 80 per cent over the tropical city of Bhubaneswar.

Using the data on urbanisation and temperature of the last two decades, Vinoj and Sethi investigated the contribution of local-scale urbanisation and regional climate change to the observed surface warming in 141 major Indian cities.

By leveraging 18 years of high-resolution land surface temperature data from the MODIS sensor on NASA’s Aqua satellite for the period between 2003 and 2020, the research team carefully compared urban and rural warming trends.

Among the top-20 cities that have shown the highest urban contribution leading to warming, Bhubaneswar does not find a spot and Jamshedpur leads with a contribution of 100 per cent followed by Raipur (77.7 per cent) and Patna (67.1 per cent), the study states.

It pointed out the changed urban landscape no longer benefits from evaporative cooling. Instead, it accumulates heat due to many factors such as higher-thermal-inertia surfaces (like concrete and asphalt), surface albedo (fraction of light that a surface reflects), and enhanced human activity, thus leading to the urban heat island (UHI) effect, which subsequently affects other climate parameters like rainfall, pollution and so on.

The researchers underscored the importance of targeted urban planning and efforts to mitigate heat impacts, which could also address other urban issues like extreme rainfall, floods, and air pollution. Targeting smaller cities with systematic heat action plan is expected to be far cheaper with a positive outcome than for large urban agglomerations or mega cities, they stated.

Associate professor Vinoj said a lot more aspects related to urbanisation are still unexplored in the Indian context. “However, this study provides an early glimpse of science-backed information that may be useful for national or state level policy-making to view each city differently and allocate limited resources systematically to reduce warming of our cities. Such an approach will help in implementing policies that may make our growing smart cities smarter,” he added.

As per Global Climate Risk Index 2021, India is the 7th most impacted country by climate-related extreme weather phenomena. Also, studies indicate that India will be one of the most vulnerable countries to the impact of climate change with its cities at the forefront.

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