Her home was only a few minutes from the sea, but for Sheema, a domestic worker living in Karachi’s Neelum Colony, it may have been a continent apart. When the first heatwave of the summer set in, the sweltering temperatures left her sister delirious, with a pounding headache and burning eyes, barely able to manage the 10-minute walk home from their workplace.

As the sun burnt into their backs, Sheema and her sister pleaded for a nearby mosque to take them in, even if it was just for a few minutes. Inside, they reclined under a fan, their parched throats wishing for nothing more than a glass of cold water.

“After working all day, our walks back home used to be pleasant as a gentle breeze would blow from the sea,” said Sheema. “Now, high-rise buildings around our neighbourhood have hemmed us in a hot bubble where it is difficult to even breathe.”

Karachi, one of Pakistan’s most densely populated cities, has rapidly expanded over the years, with its built-up land cover increasing from 667.01 km2 in 2015 to 715.794km2 in 2023 at an average annual growth ratio of 13.35 per cent, according to a study. This rapid urbanisation has gulped down both agricultural and barren land, adding to the concrete jungle that is Karachi.

Neelam Colony, where Sheema and her sister live, is located near the Abdullah Shah Ghazi shrine — one of the city’s most revered saints. In recent years, the area has become hotter as the cooling sea breeze fails to reach it, primarily due to unplanned densification, giving rise to a phenomenon known as the urban heat island (UHI) effect.

The UHI effect, by definition, is a phenomenon where urban areas experience higher temperatures than outlying areas due to the combination of various factors such as diminishing green cover, heat gain, thermal properties of materials used in urban surfaces as well as heat from human activities such as industrial processes and transport.

Buildings and paved surfaces — like major roadways and industrial zones — trap the heat and amplify it, while areas dense with parks, playgrounds and greenbelts stay relatively cooler. Within Karachi, central business districts such as II Chundrigar Road, MA Jinnah Road and Saddar feel hotter owing to minimal green cover and plenty of asphalt that absorbs solar energy.

During the heatwave that Karachi braved again yet again this year, the UHI phenomenon was widely witnessed. “We recorded a difference in temperatures in neighbourhoods within the city as some areas remained hotter than others,” Chief Meteorologist Dr Sardar Sarfraz told Dawn.com.

He explained that the Pakistan Meteorological Department has four observatories in Karachi, located in Port Qasim, Old Airport area, Faisal Base and Masroor Base. In this case, the mercury recorded at Masroor Base — a relatively open space — used to be two degrees lower than that recorded at Port Qasim, which is brimming with industrial activity. “Areas with open spaces and green cover often record lower temperatures than denser and more populated ones,” explained Sarfraz.

This year, Sindh witnessed three major heatwaves — towards the end of May, June and July — as the mercury reached up to 50 degrees Celsius along with choking humidity, which Sarfraz said exacerbated the temperatures. The temperatures recorded in June were the highest since 2015, he added.

Heat and death

According to Mohammad Ameen, the control incharge of the Edhi Foundation in Karachi, their mortuaries saw an over three-fold increase in the number of bodies this summer. He added, however, that his organisation could not declare whether these victims had died from heatstroke.

“This is the government’s job,” he told Dawn.com. “But there was a time during these three months when the number of bodies arriving at our morgues was in the hundreds.”

Data from Edhi morgues across the city showed that over 1,500 bodies were brought to the facilities from June 15 to June 30. The highest number was recorded at 141 on June 25, when the temperature in Karachi crossed 40 degrees Celcius for the second consecutive day.

Saad Edhi, the Edhi Foundation’s spokesperson, also confirmed this. “We may not be able to confirm the reason for these deaths, but the symptoms highlighted by the families, including high fever, dehydration and unconsciousness, all point towards heatstrokes,” he said.

However, the provincial health department’s data does not corroborate with the numbers shared by Edhi and other welfare departments. Dawn.com reached out to the department but didn’t hear back from them.

Jahangir Durrani, spokesperson of the Jinnah Post-Graduate Medical Centre, said that the facility recorded five heat-related deaths between May 22 and Aug 8.

JPMC also set up a special heatstroke ward where hundreds of patients were treated every day. Dr Nausheen Rauf, head of the hospital’s emergency ward, said that the facility began watching out for heatwaves at the beginning of May, highlighting that an influx of heat-related cases started coming in June and July.

“Most of the people brought in were drug abusers, people living on the streets, security guards and the labour class who had complaints of high fever, vomiting, dehydration, drowsiness and gastroenteritis,” she recounted. “A majority of these cases were from Saddar, Shah Faisal and neighbouring areas.”

She added that after the 2015 heatwave, this year saw a significant number of heatstroke cases. A similar situation also persisted at the Dr Ruth Pfau Civil Hospital Karachi and other health facilities.

Sheema’s sister too had a high fever by the time she reached home that day. But the narrow asphalt roads and closely-constructed buildings in her neighbourhood, that trap the heat, prevented her from feeling any better. Later at night, she was moved to the nearby Indus Hospital where she was treated for a heatstroke.

Urban sprawl

Ganga Kumari, a 45-year-old lean woman, sits on a charpoy in the close-knit streets of Ranchor Line, one of the oldest and most dense settlements in Karachi. Beads of precipitation run down her face as she fans her husband, who is recovering from heart surgery, with an old newspaper.

Her street, once wide, has now been engulfed by encroachments, leaving only space for motorcycles and residents to pass by. Over the years, five-storey buildings have been erected on 120 square yards of land, each featuring at least eight apartments. The stuffed and dingy flats don’t allow air to pass. Venturing further into the neighbourhood, the houses get even more crammed until you can hardly see the sky above.

With Ganga sit a bunch of other women and men, all of them talking about the day’s activities. But soon the chatter subsides into silence as the heat begins to take its toll.

“This is an everyday routine … what can you do when it is so hot and there is no electricity,” she lamented. “These streets and the rooftops have become our abode, inside the house, it feels as if someone has locked us up in a hot room … it is difficult to even breathe.”

“My husband has it worse … the heat suffocates him and increases his blood pressure,” said Ganga, who works at a nearby school as a sweeper. “There is not even an open space or park nearby where we can go.”

Basically, concrete is making Karachi sweat, that too profusely.

Dr Noman Ahmed, head of the Department of Architecture and Planning at NED University, explained that commercial areas have air-conditioners that keep the indoor environment cool but their outer units work as exhausts that remit heat into the atmosphere.

City corridors that have tall buildings — the likes of Sharea Faisal, Tariq Road and Shahra-i-Quaideen — therefore, feel the heat island effect intensely. “These buildings block the wind corridor, so the heat instead of moving forward and dissipating, gets trapped in these locations and its impact is felt for a longer period of time,” Dr Ahmed explained.

It may not seem too important, but the colour of the material used for the infrastructure also plays a vital role here as it absorbs heat during the day and later radiates it out after sundown.

Moreover, UHI is also generated on streets and roads with high vehicular flow and traffic congestion where the heat generated by car engines gets stuck, increasing the felt temperature for people in the neighbourhood. The ground surface, usually asphalt, further enhances the heat retention.

And then there are informal settlements, home to a significant percentage of Karachi’s population, that contribute to the UHI effect by limiting air circulation and allowing heat to build up.

“Old katchi abadis located closer to the central areas of the city, such as Lower and Upper Gizri, Punjab Colony, Delhi Colony, Neelum Colony, and Lyari among others, initially had the normal pattern of development — ground or ground plus one structure. But they have now been replaced by six-storey buildings, standing very close to each other, that prevent air and sunlight from passing.

“This creates a very unhealthy environment in these areas; especially when the wind is scarce, it creates suffocation,” said Dr Noman, recounting that during the 2015 heatwave, hundreds of people hospitalised were those belonging to these informal settlements.

Muhammad Toheed, an urban planner and geographer, concurred, adding that this was further exacerbated by frequent power outages lasting 10 to 14 hours in many informal settlements.

“Without access to electricity, residents suffer from extreme heat, leading to health issues such as heatstroke, dehydration, and other heat-related illnesses. The absence of greenery and shade only worsens the situation, making living conditions in these areas unbearable,” he added.

Where did the trees go?

Naveed Khan, a mechanic based in Lyari, may not be able to spell it out accurately but he knows all too well the curse of urban heat islands. One day in June 2015, he rushed home after begging his employer for a half-day. His seven-year-old son, who was playing in the streets with friends, had fainted. It was a heatstroke. Although generally believed to be easily curable, the episode damaged his kidney, leaving him writhing in pain for several days.

Even when he came back home from the hospital, Naveed and his wife would spend days by the bedside, taking turns to fan the little boy. Naveed lost his job that year too, and had to look for odd jobs to make a living.

According to Sarfraz, the temperature in Pakistan is becoming 0.18 degrees warmer per decade. But Karachi has it even worse, with its mercury increasing twice that of the country every 10 years. The chief meteorologist puts the blame on rapid urbanisation and deforestation.

As Karachi’s intermediate green cover continues to decline, the city’s population has swelled from 16.02 million in 2017 to 20.3m, as per the National Digital Census 2023. Of the city’s seven districts, East emerges as the most populous with 3.9m people, followed by Central with 3.8m, Korangi with 3.1m, West with 2.6m, Malir with 2.4m, South with 2.3m and Keamari with a population of over 2m people.

The data also showed massive rural-to-urban migration which translates to greater urbanisation, forcing a large portion of the population to undergo disproportionate forms of heat stress as non-urban land and greenbelts are converted into urbanised landscapes.

One such example, as highlighted by Nazifa Ishaq, the director of climate action and sustainability at WWF Pakistan, is the construction of the Green Line bus service, which resulted in the casualty of 9,000 trees just in the development of one of its five routes.

This is routine in Karachi, where playgrounds and greenbelts are often lost in the guise of government projects, from the widening of roads to the construction of the Malir Expressway. These actions, and many more, have turned Pakistan’s economic hub into a concrete jungle.

While the provincial government has, in recent years, announced a number of urban greening projects in the city, they are focused more towards “beautification rather than meaningful ecological impact”, Nazifa decried. She pointed out that the Karachi Metropolitan Corporation had almost 1,800 parks, of which 650 were encroached and many more were unusable due to mismanagement.

In a similar vein, Toheed blamed poor management and maintenance for the lack of improvement from urban greening projects, highlighting that while they were initiated with much fanfare, such initiatives lack long-term strategies to ensure success.

“Plants and trees are often left untended after the initial planting phase, leading to their eventual demise,” he said.

Another issue highlighted by both Nazifa and Toheed was the monoculture planting of ill-suited plant species such as Conocarpus — introduced by the KMC in the 2000s. “It acts as a windbreaker, creates a vacuum and increases the heat index further,” said the WWF director.

She lamented that 50pc of Karachi’s trees were exotic alien species, adding that there was a need to plant indigenous and regionally appropriate species that were more sustainable and improved biodiversity in the city as compared to the former.

Meanwhile, Toheed added, “For urban greening to be effective, it requires continuous care, appropriate species selection, and community involvement to maintain and protect green spaces.”

Finding ‘clean’ solutions

Shahroz Siraj, popularly known as the ‘Tree Man of Pakistan’, is among those few people in Karachi who have taken on the responsibility to make the city breathable again. An engineer by profession, he embarked on the ‘green’ journey after the 2015 heatwave, when, Siraj recalled, mortuaries and hospitals were full to the brim.

“The first tree I planted was in North Karachi’s Sector 9,” he told Dawn.com. “One would assume that it would have been an easy job, but the reality is far from it. I remember I had knocked on a door in our neighbourhood and requested that the family water the newly planted sapling nearby. They downright refused, saying that they hardly had water for other chores.”

The next door Siraj went to too had a similar response. “That is when I realised that greening the city was directly proportional to awareness.”

Hence began the Tree Man’s drive. In the last nine years, he has visited madrassahs, schools, colleges, mosques, imambargahs and churches to educate fellow citizens about the importance of trees. During this time, he planted 150 tree saplings and set up four urban forests in his area.

“It is the responsibility of every person to plant at least four trees,” he stressed. “Trees are our sole solution as they turn carbon into oxygen. You can’t stop the temperature from rising, but you can at least create cool shades to rest under.”

Climate experts also told Dawn.com that the solution to Karachi’s woes lay in the transition to cleaner energy among other measures. The industrial sector, for one, can shift to renewable energy sources which would not just reduce emissions but also decrease the overall heat produced.

“Clean energy solutions often involve more efficient technologies that produce less heat and use less energy overall. This transition can help lower overall city temperatures and reduce the strain on the power grid (on-grid and off-grid options) leading to fewer outages and more reliable access to cooling during heatwaves or extreme temperatures,” remarked Toheed.

By reducing reliance on fossil fuels, the amount of waste heat generated in the city can be lowered. Solar panels, for example, can provide energy without producing additional heat, unlike traditional power plants.

However, Dr Noman highlighted that the current usage of solar in the city was rather haphazard. “People are using it in their homes and offices but that isn’t bringing about a larger positive impact … instead, we should integrate it into bulk energy production and the main grid,” he said, adding that there was a need to strategise solar usage.

When it comes to transportation, Karachi can promote the use of electric vehicles and improve public transportation to reduce heat and emissions. Nazifa highlighted that Euro5 fuel, which minimises the negative impact on the environment owing to a reduction in Sulphur and Benzene content by 98pc and 80pc respectively, was available but not completely adopted.

“Ideally the government should plan to switch to Euro6 because vehicular emissions contribute greatly to heat-trapping gases,” she said.

In the construction sector, adopting green building practices such as using reflective materials and incorporating natural ventilation can reduce the heat generated by buildings.

“Designers and architects should concentrate on green building designs and create zero-emission or energy-efficient buildings using lead certification — which is declaring buildings as low emission,” Nazifa stated, adding that shifting industries away from densely populated urban areas can also mitigate the effect of heat island effect.

Dr Noman, meanwhile, suggested cheaper solutions such as choice of paints — using white could help as it reflects the sun rays — and adding a layer of “choona” in the buildings. There are also other common techniques for vertical landscaping, whereby plantation can be introduced in highly congested areas.

The government also needs to seriously work on the regulation of informal settlements because unplanned densification of these areas is dangerous. For this, the NED dean has a solution.

“If there is more pressure on an area, a scientific exercise called urban regeneration can be adopted, through which small plots can be amalgamated into a big plot and there you make tall structures via proper planning which include open spaces and amenities. Here, people can be then accommodated via a proportionate formula,” Dr Noman suggested.

That said, there are a number of policies that the government has introduced of late such as the National Electrical Vehicle Policy and National Cooling Action Plan. But they lack implementation.

“While policies like promoting electric vehicles and renewable energy are introduced, they often fail due to poor coordination, inadequate funding, and insufficient public awareness,” said Nisar Ali, climate resilience associate at the Asian Disaster Preparedness Centre.

“It’s not just about announcing policies; it’s about making sure there’s a solid plan to implement them effectively. This means allocating enough funding, providing incentives for the public to adopt these changes, and creating clear, enforceable regulations.”

Integrating climate resilience into urban planning is crucial, especially for cities like Karachi, where the impact of heatwaves is severe. The government needs to think long-term and ensure policies are practical, actionable, and backed by proper resources, he added.