The temperature of Dhaka has been rising beyond expectations compared to that of nearby rural areas due to the rapid pace of urban development among other reasons, a research has found.
It found that the average temperature of Dhaka remains about two degrees Celsius higher than that of the rural areas in summer and monsoon. The temperature remains higher at night.
Also, the rise in temperature in planned areas – such as Gulshan and Uttara – is higher than that in unplanned areas because of the high use of cooling technology.
Curtin University of Australia, Dhaka University's Meteorology Department, and Bangladesh Institute of International and Strategic Studies (BIISS) conducted the research from August 2018 to December 2019.
The findings of the research were presented in a seminar titled "Mitigation strategies for warming of Dhaka megacity: Implication for sustainable development" on Sunday at the BIISS auditorium.
"The result of the temperature of Dhaka and nearby rural places was derived by installing machines in different areas which is consistent with around 17,000 satellite images. It implies that our research findings are correct," said Mahfuz Kabir, research director of BIISS.
"We also analyse the data on temperature from the past 17 years," he added.
Dr Shamsul Alam, member of the Planning Commission, said, "We need urbanisation but not in a few places only."
According to the research, construction and vehicular movement, and declining vegetation and waterbodies are also responsible for a warmer Dhaka.
Speaking about rooftop gardening, Shamsul said, "We have to determine actual consequences for adopting any new initiative or technology. Rooftop gardening requires groundwater. Rainfall harvesting should be prioritised instead of using groundwater."
"We need to have a clear groundwater map of the whole country. If the delta plan can be implemented, Bangladesh will be able to export freshwater in the next century," he added.
Professor Dr Nazrul Islam, a well-known urban planning specialist who chaired the seminar, said, "Dhaka North City Corporation has been trying to popularise rooftop gardening, but any policy recommendation should be based on research."
Climate change specialist Dr Saleemul Huq said, "10 million people will be the victims of forced displacement due to climate change in Bangladesh. A very large number of these people will come to Dhaka. We have to be prepared for that."
"The nature-based solution has to be identified for urban development," he added.
Dr Ashraf Dewon, one of the keynote speakers of the seminar, said, "Dhaka is the fourth largest megacity in terms of population. Urban temperature is rising faster than expected."
Recommendations of the study
The study recommended buildings be constructed in a way so that there is enough space in interior and exterior as well as ground premises that can be best utilised for plantation.
A minimum rebate should be applied for any microgreen space (gardening) in the building and should be up to 30 percent of the holding tax depending on the extent of gardening in rooftop, balcony, lawn, and interior and exterior.
Private offices and business venues with green interior and exterior should get tax benefits, such as corporate tax and VAT.
Building designs should be encouraged through special fiscal incentives.
Corporate tax and cash incentives should be provided to the architecture firms that design green buildings only.
The study suggested Rajuk (Rajdhani Unnayan Kartripakkha) issue a guideline for all building designs so that a minimum space can be dedicated to green-blue spaces.
It also said large canals, lakes, and parks should be integrated and rejuvenated to have a significant impact on the rising temperature of Dhaka.