Chennai’s heat and humidity heading to critical threshold

“It is most likely that a city like Chennai will face the double whammy of heat and humidity, and cyclones, which are also predicted to be on a rise under a 1.5-degree scenario.

Published: 02nd March 2022 05:38 AM  |   Last Updated: 02nd March 2022 05:38 AM   |  A+A-

Ennore’s thermal power plants are a big source of Chennai’s pollution. IPCC says Chennai could have wet-bulb temperatures of 32-34°C by the end of the century | P Jawahar

Express News Service

CHENNAI: The Intergovernmental Panel on Climate Change (IPCC), in its latest report, identified Chennai among several Indian cities facing the risk of breaching the critical threshold of wet-bulb temperatures, a measure that combines heat and humidity.

It says under RCP8.5 (high emissions scenario), by the end of the century, Lucknow and Patna are among the cities predicted to reach wet-bulb temperatures of 35° Celsius if emissions continue to rise, while Bhubaneswar, Chennai, Mumbai, Indore, and Ahmedabad are at risk of reaching wet-bulb temperatures of 32-34°C with continued emissions.

Explaining what this means, Dr Anjal Prakash, IPCC lead author of chapters on cities and mountains, told TNIE high-resolution climate change simulations suggest that due to deadly heat waves projected in some densely-populated regions of South Asia, the critical threshold of the wet-bulb temperature of 35°C will be exceeded under the business-as-usual scenario of future greenhouse gas emissions. 

“It is most likely that a city like Chennai will face the double whammy of heat and humidity, and cyclones, which are also predicted to be on a rise under a 1.5-degree scenario. The impact will be directly on older people and those who have comorbidities,” he said. Climate experts say a wet-bulb temperature of 31°C is extremely dangerous for humans, 35°C is unsurvivable for more than about six hours, even for healthy adults resting in the shade.

Dr Prakash, who studied in Chennai and knows the issues plaguing the city, said the Tamil Nadu government should make enhanced budgetary allocations to improve the city’s resilience and combat what is impending. “We don’t have much time. The government has to act now. The IPCC assessment is only an indicator. A State-level or district-level study should be carried out and mitigation measures should be shaped accordingly.”

On Tuesday, the wet-bulb temperature for Chennai was 24.4°C. Last summer, it breached 30°C. When contacted, Additional Chief Secretary Supriya Sahu said she was aware of the IPCC projections and the State government is taking several steps to mitigate climate change.

“It will be a very tall claim to say we can reverse climate change; however, major measures are in the pipeline. For Chennai, under the Tamil Nadu Green Mission, we are going to set up micro forests. I have already written to various departments to identify vacant OSR, poramboke and other government lands to plant native species. The TN State Action Plan on Climate Change 2.0 has been finalised and will be shortly put forth before the State committee before being forwarded to the Union Environment Ministry for approval.”

Sahu said the government has made available adequate funds and fresh allocations are expected in the forthcoming budget. DMK MLA TRB Rajaa, who is also a member of the State Planning Commission, said, “In Tamil Nadu, many are affected by crop loss, excess rains, sea-level rise etc. We laid out our plans to deal with climate change in last year’s budget, and are actively working on the same. We are also coordinating with industry leaders and looking into how we can work on carbon sequestration, increasing our forest cover, and cutting emissions. The State is also giving a strong push for electric vehicles and renewable energy.”


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