Heat action plans: Why cities are not measuring micro climatic zones - Hindustan Times
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Heat action plans: Why cities are not measuring micro climatic zones

ByHindustan Times
Jun 17, 2023 02:31 PM IST

This article is authored by Dileep Mavalankar, director, Indian Institute of Public Health, Gandhinagar.

In recent times, there have been heat waves in many parts of the country. Several cities reached max temperatures of 43 C and above. Due to the climate crisis, such heat waves are increasing in many parts of India and the world. Starting from the pioneering heat action plan of Ahmedabad city developed in 2013 by Ahmedabad municipal corporation, Indian Institute of Public Health Gandhinagar (IIPHG) and National Research Development Corporation (NRDC) jointly by looking at heat related 800 excess deaths during the 2010 heat wave, National Disaster Management Authority (NDMA) has helped many state and cities to develop Heat Action Plans. Since 2016, India Meteorological Department (IMD) has developed heat prediction system in the whole country which gives five days advance forecast of temperature and heat waves. But IMD is a national agency with limited resources and a national wide mandate, hence their predictions are over very wide area – such as heat wave is likely over parts of Uttar Pradesh, Bihar, Bengal and Orissa. Even though such predictions are useful but the cities and districts need much more precise information of heat wave locations and magnitude of. It is very good that IMD now predicts temperature in 1,000 cities in India. IMD has about 1-3 weather stations in each district, and regular temperature from big cities is reported only generally from one main weather station located at the airport. Airports are generally located away from the centre of the city and have much open space with no buildings nearby. So, such temperatures reported are not really reflective of the city centre temperatures which are much higher – about 2-6 deg C higher. This is called urban heat island (UHI) Effect. When 45 C temperature is reported in some city, so inner city area could be much hotter at 48 C. As our measuring instruments density is very less even in big cities we only get a very general idea of the temperature. Given cities constructing and layout as well as use of vehicles and air conditions and other heat emitting sources and heat absorbing black tar road etc some part of the city develop micro climatic zones which are as of now not measured in any city except a few such as Pune where the IMD major office is located.

Group of demonstrators on road. (Getty Images/iStockphoto)
Group of demonstrators on road. (Getty Images/iStockphoto)

These micro climatic zones may have much impact on human health, wellbeing and productivity. But even in today’s smart city initiative public is not getting information of such micro climates in the city. Recently with a World Bank supported project the City of Johannesburg measured local temperature and various wards of the city to find that there a difference of 6 C temperature in poor area and rich areas. Such inequities in micro climates will be exaggerated as global warming progresses further over next 80 years. Unless we start measuring such micro climatic data from various areas of the city we may be missing vital information which will be useful for developing and finetuning city heat action plans for future.

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IMD alone cannot provide ward by ward climate information for the 5000+ cities and towns of India. The city and town local authorities have to invest funds to install automated weather stations (AWS) in various wards of the city and collect the local temperature and related data. Such temperature data should be correlated to morbidity and mortality data of the ward. Of course, IMD has to guide this effort so that the cities select the proper calibrated instruments and locate them in a scientific way to get valid measurements. Good AWS cost 3-5 lakhs which is not a high price to pay for any city or town given the fact that it will provide vital weather information which may help to set up local heat alert thresholds and make the heat action plans more effective. It will also help identify hotspots that need cooling by planting more trees and take other measures. The state government should support such efforts via urban development and other departments. The central government can also pitch in to support such efforts via the climate crisis and smart city initiatives. The State Disaster Management Fund should be used for such activities to prevent heat related disasters.

Satellite pictures provide land surface temperature and infrared radiation reflected back from earth which gives the indication of local heat islands. Such information should also be compiled by the cities and publicized to alert the public about micro climatic zones in a city and the temperature variation.

We must get all the common weather parameters to the citizens and not just the temperature and humidity or rain. Other measure such as globe thermometer temperature which give measure of radiant heat – which indicates what will happen if you stand or sit directly in sunlight. The death of unfortunate 13 people in New Bombay Khargar area meeting few weeks back was due to direct radiant heat. The local temperature there was reported as 38 C which is not so high to cause heat stroke if people were in a shaded place. The temperature which IMD report is of ambient air temperature in a shaded white colored wooden box which is much lower than the heat received if one stands directly in sun light. IMD should also give WBGT readings which combines web bulb and globe thermometers readings. Thus it takes into account humidity and radiation. WBGT above 37 C is considered as very hot and person can develop heat stroke quickly at this temperature. IMD or the city should measure various parameters of the weather and inform the public in real time.

Sometimes simple instructions to the public can save many lives, eg, if in Khargar new Bombay people were told to bring umbrellas to protect from direct sunlight many lives could have been saved. In Ahmedabad Heat action plan simple advice during heat seasons and red alert days have saved almost 1,200 lives every summer as per one preliminary estimate based on data. The city government have to be more proactive in measuring weather parameters at various locations in the city and informing the public about the heat situation in a more granular fashion rather than just on max and min temperature of one place in the city.

Such information along with resilience measures like greening of the cities, free drinking water during summer and readiness of the health system are very low-cost interventions which will save many more lives in future when the average temperature goes up by 2-3 degrees.

This article is authored by Dileep Mavalankar, director, Indian Institute of Public Health, Gandhinagar.

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