Researchers and urban experts said on Wednesday temperature of the cities has been rising due to unplanned urbanisation, destruction of natural greens and blue network and climate change creating health hazards for humans.
Various studies have found that the surface or ground temperature of Dhaka city has increased from one degree Celsius to three degrees Celsius between 1991 and 2011.
Experts have predicted that if carbon emission continues at the present rate, the mega cities of South Asia, including Dhaka, will experience more heat waves by the year 2025 as the temperature will cross human survival rate of 31 degrees Celsius.
But most of the cities will not survive in 2075 if the carbon emission rate exceeds the present trend.
They made the observations at an inception workshop on 'Mitigation Strategies for the Urban Microclimate of Dhaka Megacity to Reduce Adverse Climate Change Impacts,' a research project funded by World Bank.
Bangladesh Institute of International and Strategic Studies (BIISS) organised the workshop at its auditorium.
BIISS, Curtin University of Australia and Meteorology Department of Dhaka University will conduct a one-year research to be completed by December 2019.
Curtin University Professor Ashraf Dewan and BIISS researcher Mahfuz Kabir presented papers on the theme.
General Economics Division (GED) member Shamsul Alam was present as the chief guest.
In his presentation, Mr Ashraf said the temperature in urban areas has been increasing more than the rural areas due to high-rise buildings, population density and wrong street orientation reducing evaporation.
"Urban areas are warmer than the rural areas, popularly known as urban heat island (UHI). The microclimate problems have contributed in the enhanced survival rate of new kind of vectors like mosquito and other germs causing new diseases like dengue, chikungunia and respiratory diseases," he said.
The temperature of Dhaka has also risen due to increased use of the air conditioner and obstruction in passage of wind for the high-rise buildings, he added.
Citing Im et al (2017) prediction, Mr Ashraf said, "We are afraid that the magnitude of heat waves will increase in South Asia, especially in mega cities like Dhaka, Kolkata, Delhi, Mumbai, Bangalore, Karachi and Lahore as the temperature will cross the human survival rate of 31 degrees Celsius by 2025 if the present carbon emission rate continues".
Through the research project, the researchers will observe the temperature of roads, buildings and various spots to detect the critical areas and to sort out mitigation and adaptation measures to save the city before it affects the country.
Member secretary of Bangladesh Paribesh Andolon (BAPA) Iqbal Habib said the area of Dhaka city has increased 19 times and its population density 25 times after the country's independence till 2010.
Expressing dissatisfaction over non-implementation of any plan for Dhaka after 1959, he said no new plan will be meaningful if the previous plans are not implemented.
He underlined the need for implementation of the revised Detailed Area Plan (DAP) along with the urban revitalisation and vegetation programme.
Mr Iqbal stressed creating blue and green network, with special emphasis on reclamation of the canals and undertaking of effective measures to return to green network.
He believes that 42 out of the total 52 canals of the capital can still be reclaimed.
"Water flow can massively control city temperature," he added.
The government should be strict in enforcement of various rules and regulations to save the environment, said Mr Iqbal.
"The role of the regulator should be stringent. The city corporations and Rajuk should play the role more of a regulator than of a developer," he said.
Shamsul Alam said in 1971, average temperature was 25.6 degrees Celsius which has increased to 1.1 degrees Celsius in 48 years.
Referring to Delta Plan 2100, he said it has included the adverse impact of climate change and how it will affect the economic growth, production and employment.
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