Chennai the number of heat wave days will double before 2050 in 21 cities across Tamil Nadu, including Tambaram and Avadi, says an Anna University paper on climate change.
According to the draft report ‘Climate Risk Assessment and Adaptation Plan for Tamil Nadu – Sustainable Habitat’ (1990-2020) prepared by the Center for Climate Change and Disaster Management (CCCDM) at Anna University, Tamil Nadu’s temperature will rise, northern coastal areas and urban areas will be more affected. T Next reported.
The report indicates a trend towards increasing temperature days, which could mean up to 250 days of high temperatures per year by 2050. The urban climate risk assessment highlights that cities in the north coastal areas such as Chennai Corporation and surrounding areas of Avadi and Tambaram are exposed to high levels of climate risks. Tirunelveli, Trichy, Thanjavur, Kumbakonam, Madurai, Sivakasi, Dindigul, Nagercoil, Kanchipuram, Tuticorin, Cuddalore and Salem are at moderate risk due to climate change, while Karur, Tirupur, Hosur, Coimbatore, Erode and Vellore face low risk, the report said.
An extreme urban heat island effect and peak temperatures put urban areas at risk, the study said, with Chennai, Nagercoil, Thanjavur and Tuticorin experiencing an average of more than 40 days of heatwaves per year during 1985-2014, the report said. But the report estimates that the number of heat wave days will double over the next century.
If the maximum temperature is 4.5 degrees Celsius above the normal temperature, the India Meteorological Department calls it a heat wave.
The annual average heat wave days in Chennai will increase from 42 days to 81 days. Similarly, the annual average heatwave days in Avadi and Tambaram will increase from 43 and 42 days to 80 and 78 days respectively. Kanchipuram, which has 39 heat wave days, will have 74 heat wave days by 2050, according to the study.
Out of all the 21 cities likely to face extreme heat waves in the future, Chennai is the most affected. According to the overall vulnerability assessment, Chennai is the most vulnerable city in Tamil Nadu with high population density and high population of homeless people. Poor infrastructure and socio-economic factors make these groups more vulnerable to heat stress and related diseases, the report said.
According to the Urban Green Guidelines 2014, Chennai has a deficit of 62 sq km of greenery out of 21 cities, leading to more heat wave days. Out of a total area of about 438 sq km, Chennai has only 8 sq km of green space instead of the recommended 79 sq km. Also, 9 sq. km, there is potential for additional greenery. Coimbatore has only 7 sq km of green area instead of the recommended 60 sq km. Coimbatore has an additional potential of 13 sq km. But there is a shortfall of 40 sq km. On the other hand, Avadi has a shortfall of 5 square kilometers.
Interestingly, Kanchipuram and Tambaram and Nagercoil have shortages. Under the Urban Greening Guidelines, the Ministry of Urban Development recommends that the ratio of parks, open spaces, water bodies and other recreational areas to the total developed area in medium-sized cities and large cities should be 18-20%. In metropolitan cities, this ratio should be 20-25%.
In this scenario, it is essential to promote greenery in cities where green space is limited. Cities that exceed the recommended green area should be protected against further degradation due to future growing population. Although urban forests are man-made, the results suggest that more attention should be paid to urban forest management, the report said.
On the other hand, increasing temperature and heat wave will reduce isotropy (amount of temperature variation throughout the year) which will affect vegetation and biodiversity. During 1985-2014, the average temperature in Tamil Nadu’s cities ranged from 51 to 67, which will decrease to 48-65 in 2050. Decreasing isotherms will result in higher daytime temperatures within cities. Higher temperatures worsen air pollution. Chemical reactions in the atmosphere lead to smog formation and increased ground-level ozone, the report said.
“The Tamil Nadu Department of Environment, Forest and Climate Change is developing an urban greening policy to increase green cover in cities. “The policy will be developed to extend various aspects of greening the city to the whole of Tamil Nadu through urban parks, residential parks, vertical gardens, green areas around industrial areas,” said a senior environment department official.
Also, an urban policy on greening will be part of the Green Tamil Nadu movement. To implement this, cities and corporations will have a dedicated unit consisting of botanists, horticulturists, landscape architects and others, the official said.
