Unplanned urbanisation turns Dhaka into heat island

Dhaka is becoming increasingly hotter as rapid and unplanned urbanisation, shrinking green spaces, loss of water bodies, growing traffic and extensive use of fossil fuels intensify the urban heat-island effect, according to experts and available studies.

The transformation of open and vegetated land into concrete structures has reduced the capital’s ability to absorb heat and cool naturally. Buildings, roads and other paved surfaces absorb solar radiation during the day and release the stored heat slowly, keeping densely built areas warmer even after sunset.

Climate change and rising global temperatures are adding to the pressure, while Dhaka’s rapid population growth and increasing demand for housing, transport and infrastructure have accelerated changes in land use.

Dhaka’s population has expanded dramatically over the past four decades. The city’s population was estimated at around 5.2 million in 1986, while recent estimates place the wider urban population at several times that figure.

Rapid population growth without a proportionate expansion of urban space has contributed to increasingly dense development. Between 2001 and 2017, Dhaka’s population reportedly increased by 77 per cent while its land area expanded by only 19 per cent, intensifying pressure on available land and encouraging a concrete-dominated urban landscape.

One of the most significant changes has been the disappearance of trees and other vegetation.

A study by the Centre for Atmospheric Pollution Studies (CAPS), titled “Land Use and Land Cover Change Analysis of Dhaka City: 2015-2025,” found that the city lost 31 per cent of its tree-covered area over the decade.

According to the study, vegetation covered 3,784.19 hectares, or 12.52 per cent of the studied area, in 2015. By 2025, it had fallen to 2,608.99 hectares, or 8.63 per cent. The study also found that water bodies declined by 47 per cent during the same period, while built-up areas expanded by 50 per cent.

Longer-term figures also point to a substantial decline in greenery. Dense vegetation in Dhaka reportedly fell from around 17 per cent, or 5,202 hectares, in 1989 to about 2 per cent, or 612 hectares, by 2020.

Experts say the simultaneous loss of trees and water bodies is particularly damaging because both play an important role in regulating urban temperatures.

Trees provide shade and release moisture through evapotranspiration, while ponds, lakes, canals and wetlands can help cool their surrounding areas.

As those natural cooling systems disappear and are replaced by concrete, asphalt and other heat-absorbing surfaces, temperatures rise.

Traffic is another contributing factor. Bangladesh Road Transport Authority data indicate that around 2.39 million motor vehicles were registered in Dhaka by mid-2026. Vehicle engines release heat as well as air pollutants, adding to the environmental pressures faced by the capital.

Dhaka also regularly experiences high levels of air pollution. Dust from construction, road traffic and other sources, alongside emissions from vehicles and industries, has contributed to poor air quality in the city.

Environmental experts warn that the combination of extreme heat and air pollution can pose serious health risks, particularly to children, elderly people, outdoor workers and those suffering from respiratory or cardiovascular illnesses.

The city’s warming trend has increasingly raised concerns about what scientists describe as the urban heat-island effect, in which built-up areas remain substantially warmer than their less-developed surroundings.

Dr Md Saifur Rahman, Joint Secretary and Chief of the “250 Million Tree Plantation Cell in Five Years” at the Ministry of Environment, Forest and Climate Change, said increasing vegetation was one of the key measures needed to reduce urban temperatures.

He stressed the need for large-scale tree plantation across the capital, particularly in areas where greenery has been lost because of development.

He also recommended restoring and excavating ponds, canals and other water bodies to improve Dhaka’s natural cooling capacity.

Urban planners and environmental experts have similarly emphasised protecting remaining wetlands and open spaces, expanding urban forests, incorporating greenery into development projects and ensuring stricter implementation of land-use plans.

They say roadside trees, parks, rooftop gardens and vegetation around public institutions can contribute to lowering local temperatures, but isolated plantation programmes will have limited impact unless existing trees and natural areas are also protected.

The government has undertaken various initiatives aimed at increasing tree coverage and improving environmental conditions, but experts say reversing Dhaka’s warming trend will require coordinated long-term measures involving city corporations, RAJUK, environmental agencies and other government bodies.

Without stronger controls on unplanned construction and continued destruction of greenery and water bodies, they warn, Dhaka could become increasingly difficult to live in as climate change drives temperatures higher.