This is a sequel to Fahrenheit Karachi published in 2019.

Adnan curses everyone and no one as he lugs jerry cans of dead, slopping water from the filter plant at the bottom of the hill, up the steep veined alleys of Pahar Ganj to his home. It is summer in Karachi and his neighbourhood has to wait two weeks for water to even reach the taps.

The daily water run takes place after Adnan returns home from a long day of work at the Karachi Board of Secondary Education. But until the bathroom and kitchen buckets and canisters are filled, he can’t even think of putting his feet up for the day.

He struggles to keep a lid on his simmering temper as the family of five relies on him to do this backbreaking work. He takes an extra jerry can for his mother Razia, who in her mid-fifties, is fighting her own battle—to keep a lid on her high blood pressure that spikes in tandem with the city’s mercury.

These hellish March to October months are when heat and humidity suffocate Karachi, making life more and more unbearable each passing year. Most people face it with an air of quiet defeat and there is scant informed discussion linking the city’s environmental fate to the unchecked effects of global heating, which urban planners and climate scientists have long been flagging.

If the city’s runaway urbanisation does surface on the political agenda, it is only to bemoan a perceived shortage of housing or to spread fear of engineered ethno-linguistic imbalances. The fact is, however, that Pakistan, like other countries along the tropics and subtropics, is seeing the fastest rate of urbanisation, with cities in those regions most susceptible to global heating changes.

Karachi is on the list of cities, along with Mexico City, New Delhi, Dhaka, Kolkata, Cairo, Lagos, Jakarta, and Guangzhou, facing the compound effects of Urban Heat Islands and rising air temperatures from global heating.

Hot cities

Research shows that urbanisation can exacerbate global heating. Local climate is affected by rural-to-urban migration, density and population increases, anthropogenic activity and changes in the built environment, including infrastructure and land use.

In Bogotá, Colombia, a study demonstrates that densities above 14,500 inhabitants per square kilometre may cause air temperature increases of more than 1°C compared to other areas.

Now consider this: the average density of Karachi is 24,000 persons per sq kilometre, varying from 6,000 to a little over 110,000 in Lyari.

GIS expert Syeda Maha Zaidi compared temperature differences between urban and non-urban areas in Karachi. Non-urban areas experience differences between night and day, but, “There is very little change in temperatures of urban areas between day and night time,” she writes, “which indicates that urban materials continue to withhold heat and that causes the Urban Heat Island.”

Basically, concrete is making Karachi sweat.

This makes Karachi’s built-up areas warmer at night compared to open areas which are significantly cooler by as much as 5°C to 10°C. Neighbourhoods with more heat-absorbing materials and less leafy spots will collectively keep air temperatures high, well into the night.

Heat released from factories, cars and air conditioners pile on the Urban Heat Island effect. Karachi’s love affair with asphalt roads and concrete construction in the service of its ever-increasing population, is thus having an overall cooker effect. As a consequence, the materials and their colour used for city infrastructure absorb heat during the day and slowly radiate it out after sundown.

Karachi’s average temperature has already risen by 2.25°C over the last 59 years, marking an increase of 0.38°C per decade — ten times more than global temperature changes. This locks the city in a vicious loop; a rise in greenhouse gas emissions and global temperatures fuels more urban warming, which means more ACs turn on, local heat levels rise and energy demands go up.

Fatima, a 22-year-old university student who lives in Bahadurabad, describes living on the sixth floor of an apartment. “Often, I feel like the walls themselves are radiating heat … It feels like I am being cooked inside my own house,” she says.

There has been a rash of towering high-rises that have sprung up in her neighbourhood with each one progressively cutting off ventilation for the building next to it. “With the reduced airflow in our apartment, no, you cannot get a good night’s sleep without an AC,” she says.

The family recently invested in an air conditioner but it was reserved for the central room where they have to gather to sleep. This means her privacy went out the window. "It gets stressful especially if you are comfortable within your own room and then have to be okay with sharing the sleeping room with multiple people … everyone has their own timings of going to bed and as a woman, I can't dress comfortably because I have to interact with family members.” The air conditioning unit is run by a strict regimen: it can only be turned on during off-peak timings to save on the bill.

Heat stress

Hotter cities mean people are exposed to heat for longer and longer hours. The elderly, people with mobility issues, and children are the most vulnerable.

The older you are the harder it gets for your body to thermoregulate. In fact, patients rushed to the emergency with heat exhaustion during the 2015 heatwave at both the Aga Khan University Hospital and Indus Hospital were 50 years or older. In that third week of June, which coincided with Ramazan, temperatures crossed 40°C peaking at 45°C on June 22. More than 1,200 deaths were reported at government hospitals and private clinics.

It was the same story a year later as well. Farzana remembers how hot her apartment was the day she fell ill to heat exhaustion in Ramazan 2016. "It was like an oven, and I was sweating as if I had just come out of the shower," she says.

The family apartment in North Nazimabad's Block M is directly exposed to sunlight on the roof and sidewalls. The large windows did not help. “I had come back after my morning errands and decided to rest for the day. By evening, I was exhausted and began to feel slow nausea build up," she recalls. She broke her fast that evening by drinking juice but could not eat at all and her condition remained the same for the next three days.

Humidity

Exposure to sunlight or heat is not the only cause of heat stress. Humidity — a rather overlooked factor when planning around the heat — plays a larger role in testing everyone's patience to keep calm in the summers, work and be productive. When hot air temperatures and humidity mix, the human body's drive to keep cool is pushed to the upper limits of what we know as human survivability.

Since Karachi is a coastal city that gets a good share of monsoon winds, which pick up during the summers, adapting to heat stress in the background is now a citywide trend. Rising heat due to cumulative global heating and humidity from the warming of the Arabian Basin is forcing more moisture into the atmosphere. More moisture is fuelling cyclonic storms that influence what kind of heat the city will experience due to the way sea winds turn away from the city, cutting off their cooling effect. The deadly heatwave of 2015 was largely caused by a deep depression in the Arabian Basin.

The science is laid out and the predictions of how it will affect people in cities is dire. A study published in 2021 talks about how at 2°C of global heating levels, residents in South Asia and around the Persian Gulf will be exposed to heat stress levels 2.7 times compared to recent years.

Heat stress is measured in two ways: the heat index value and the lesser-known Wet Bulb Globe Temperature (WBGT). The heat index measures how hot it might feel to the human body and factors in temperature and humidity. WBGT gives a precise reading on heat stress, to include temperature and humidity as well as wind speed, sun angle and cloud cover.

People doing physical activity at 33°C to 35°C — defined as the upper limits of survivability — will face thermal discomfort that can be fatal if they cannot cool down. A stark warning from the International Labor Organisation says that at a 1.5°C global heating scenario, South Asia is expected to lose about 5.3pc of its working hours to heat stress by 2030. That corresponds to about 43 million jobs primarily in agriculture and construction. As anyone in Karachi will tell you, your ability to get any work done is inversely proportional to the weather.

“I had no other way other than using a motorbike to get to work,” explains Shafa, who was a student at the University of Karachi and was working part-time at an office located in Clifton. “Around late March or April 2019 ... it got so hot I had to quit my job.”

At the time, Shafa's commute from campus to Clifton across town took an hour and was still manageable in January weather. But her stamina dwindled as the mercury rose. It became too hot after the morning classes and her motivation to work evaporated. “I started to feel faint and just generally being in the sun with it beating down on my back,” she says. “It was too much for me.”

That year in May, she cited heat exhaustion as a health hazard in her resignation. “It was the start of Ramazan and I couldn't even drink water to keep cool."

While there are no WBGT readings taken for the Karachi 2015 heatwave, a heat index level of more than 60°C was recorded during the deadly week in the middle of June that year.

Recent studies project that large parts of South Asia spanning southern Sindh (including Karachi) and central India are already hotspots for heat stress events at 32°C. Last year in June, Jacobabad crossed the liveable temperature for the human body. The second place was Ras-al-Khaimah, a city near Dubai.

Learning to adapt to a hotter world is constricted by entrenched inequalities. The spectrum of vulnerability is demarcated by factors such as income, housing and transport.

A 20-minute drive south from the hills of Adnan’s home in Pahar Ganj, is Zahid in Saddar, a motorcycle mechanic who is frantically repairing a second-hand diesel generator. He has pulled the shutter to his workshop half down because lockdown guidelines mean businesses cannot operate as usual.

A set of computer fans rigged to the desk with motorcycle nuts and bolts attempts to battle the humidity in the closed space. At home, Zahid had tried using backup fans powered by “dry batteries” in June 2020 during the first summer under Covid-19 but now he thinks the generator would be better.

“We start to feel the tapish by 9am,” he says, referring to the Urdu word that translates here into ‘baking’. He lives in an east-facing 45-square-yard windowless house close by in Lines Area. “There are some days when it is so hot, I can hang a wet towel and it will be dry in 10 minutes.” In a bid to keep the floor cool, his family has started sprinkling water on it. The children are bathed once in the afternoon and given light clothes to wear.

"My daughter has a rare blood disease, and the humidity adds to her discomfort,” he says. “She gets seizures when it gets too hot.” That’s why fixing the generator is important. “Alhamdolillah, the load-shedding time [of over eight hours] has been shortened but we still need the fans to keep my daughter cool," he explains.

The myth is that compared to other cities, Karachi is still better placed because it still gets some sea breeze. People say that it makes the summers bearable. But the truth is that on summer days when no heatwave is forecast, it can still be unbearably muggy in Karachi.

Built environment

Unfortunately, a majority of Karachi’s housing isn’t designed for airflow that can mitigate humidity and heat stress. “Areas like Buffer Zone, Ancholi, Orangi Town … their streets are narrow, and their houses are like boxes,” says Dr Jamil Kazmi, a GIS researcher who helped supervise Syeda Maha Zaidi’s study. “There are no proper ventilation ducts, balconies or courtyards that aid in maintaining airflow. Karachi was not as hot as it is today.”

People from Punjab used to want to settle in Karachi and work away from the hot and extreme temperatures of their plains, but because of the architecture now, it is gradually growing to be unlivable.

The highest temperature recorded in Karachi's history was 47.8°C on May 9, 1938, “but no one lost their life back then, because the houses were built to keep cool,” says Dr Kazmi. “There were more trees, courtyards and patios. Now, you have tall high rises dotting the city's coastline … that don't follow a proper pattern or orientation and block the sea breeze to the inner parts of the city."

Choice of material and colour make a difference. “We selected two buildings at Hasan Square. One was cemented and the other one was painted white,” explains Zaidi. “We used a thermal camera to measure and found a temperature difference of 7°C to 8°C."

This complex interaction of global heating, urban warming and further use of heat-retaining materials in cities is already complicating life for residents. Houses in jam-packed neighbourhoods don’t have ventilation that could ease the suffocation.

In Adnan’s 45 square-yard house, for example, all they could manage was a small opening above the main door. The crush of houses on either side of the informal settlement means that no standards are followed by building contractors. To make matters worse, this area is low on the utility provider’s list and thus undergoes frequent brownouts. “I can’t sit inside the main [TV] room,” says Adnan’s mother Razia, “I feel uneasy constantly sweating.” To try to give his mother some relief, Adnan bought a car battery to run a 12V fan, which is placed close to her charpoy in the lounge, which is shared with the kitchen.

As the summer closes in, a majority of people in Karachi adjust their entire lives around power and water supplies to cope with the heat. Daily routines are overhauled to relegate laborious tasks to the cooler hours of the day. For instance, many households stop making chapatis in the hot kitchen and just buy them from a neighbourhood tandoor. Even decisions of how to get to work or venture anywhere in the city are dictated by the heat.

Women who are house-bound across Karachi for economic or social reasons suffer bad architectural design that characterises slums, a lack of urban planning for informal settlements and limited building material choices (cheap corrugated metal roofs).

Faryal’s 50-square yard home is characterised by improper ventilation, building materials that soak up and retain heat, a lack of water and electricity supplies. “I feel nauseous, disoriented, fatigued and dizzy during the hot afternoon hours,” she says. The house’s common area is exposed to the sky. “When I am doing laundry, I have to take breaks before I can go back to work.”

She also has to cope with three young children who grow restless when feeling the same heat stress. Her husband is a plumber who works in a nearby market and cannot necessarily stay home to help. So Faryal’s routine has been adjusted so she can get housework done which is why she cooks only once in the day and usually in the evening — but only if there is electricity.

While the general understanding is that humans are capable of adapting and developing a capacity to withstand the heat, this does not factor in the loss of a proper night's sleep. Across all these conversations, people spoke of a common inability to sleep in the heat, which is aggravated by midnight brownouts.

“When I don't sleep properly at night, the next day, I feel impatient, get angry at small things that go wrong,” says Zahid. “Banda hyper ho-jaata he.” (You get overwrought and stressed). This frays relationships. "The heat makes everyone irritable and grumpy," Fatima adds. "The focus to keep working while dealing with unpredictable power cuts and the heat just adds to the overall discomfort with life here.”

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Header illustration: Pablo Prat/ ShutterstockThumbnail: Adapted from Andy Tam/ Shutterstock