“They told us, stay in cool places, don’t expose yourself to the heat,” said Karachi resident Ghulam Hussain. “But the electricity comes and goes. When it goes, we run off to the mosques. Some go to the piers to find cooler air. But where are the women supposed to go if they leave their homes?”

Ghulam returned from buying food one day in 2015 to find that his wife, Razia Bano, had lost consciousness. She was soon to die of the heat, like over a thousand other Karachi residents that year.

Urban heat islands

Heatwaves are intensified in cities, where the energy used by buildings, vehicles and even the concentration of people all generate heat. Here, the water-absorbing vegetation typical of rural areas is replaced by hard and often dark surfaces such as concrete and tarmac, which reflect the sun’s rays back as heat. The concentration of buildings reduces wind flow and together with the higher water vapour content, traps heat and pollutants near the ground at night rather than allowing it to escape into the sky. As a result, city temperatures can be over five degrees warmer than in surrounding areas. The heat and pollution not only cause heatstroke but increase the rates of cardiovascular and respiratory disorders.

This urban heat island effect extends beyond the city. The temperature favours disease-bearing insects, and the warmer water flowing into other rivers harms cooler-water fish species. Fires, overloaded energy systems and the loss of working hours all contribute to lowering national production.

By 2050, the World Bank predicts that almost 70 percent of people will live in cities, doubling the current urban population and exacerbating the problem.

“We are reaching a threshold where cities can experience heatwaves that will be beyond the human survival limit,” says Dr Vishal Garg, Dean of Academics & Research, Plaksha University, who has been working with the Aga Khan Agency for Habitat (AKAH) to trial cool roofs.

“The combination of humidity and temperature to a level where we are not able to release the heat means that our core body temperature will increase and that will lead to the shutting down of different organs.”

City temperatures made frequent headlines in 2022, and are already back in the news this year. Toronto reached 26°C in April, compared to its usual average high of 10.6°C, while Dhaka reached a record 40.6°C. Shanghai recorded its highest May temperature in over a century at over 36°C.

Without air conditioning, green space in their neighbourhoods or perhaps even shelter, the poorest suffer most. Other vulnerable groups include babies and the elderly, whose bodies are more sensitive to heat, followed by outdoor labourers and athletes.

Building heat resilience: AKDN institutions respond

Dr Afsheen Ehtisham works in the health centres operated by the Aga Khan Health Services in Rahimabad and Salimabad, Karachi. During May and June, as many as half of her patients have heat-related symptoms, from heat rash, headaches and dizziness to profuse vomiting and a temperature of 105 °F (40.5 °C) or unconsciousness.

“If necessary we will refer them straight to a tertiary hospital. Otherwise, we lower the body temperature, using fans, ice packs and an IV line if needed. We should have mass education in the community centres everywhere before the hot season starts. The companies who hire the labourers must also be educated not to make them work outside during the hottest times. We have to work to survive, but we can take measures like this to avoid heatstroke.”

Dr S M Talha Arshad from the Aga Khan Health Centre, Karimabad in Karachi says that in June and July the temperature in southern Pakistan rises to over 50 °C, with more than 2,000 deaths across Pakistan from dehydration each summer:

“Prevention is very important. The Aga Khan University Hospital has a very energetic social media campaign, and AKHS also puts banners outside the clinics. I use any patient contact opportunities to give them tips – not to go outside between 11 and four or spend too long in a car, not to wear dark, tight clothing or black shoes, to drink water and juices, use sunglasses and umbrellas – and to tell them when to contact a healthcare professional. It's beneficial not only for them, but for their families.”

The Aga Khan Agency for Habitat is also conducting awareness programmes on protection against heatwaves, training community volunteers to help spread the word. But mitigating urban heat, rather than only adapting to it, requires working with the landscape.

David Boyer, former Senior Director of Environment for AKDN, was instrumental in integrating climate change priorities into the organisation’s work. “It's nice to think about a global solution, but you have to think that it took us over a hundred years to get here. It's probably going to take a hundred more years to unwind it if we take any actions now.”

David is adamant that the answers lie with civil society. “We can't wait for policymakers. People's lives are in jeopardy now. It's important that development agencies, communities, cities take action at their local level and do what they can to make sure that people can survive into the future.

“It is a cumulative process of many small actions. We've cut down most of our urban trees to make space for more roads and more development. But by putting green infrastructure back: green rooftops [covered with vegetation over a waterproof membrane], rooftop gardening, solar cooling, we can make urban areas more livable now. A lot of the Aga Khan Trust for Culture’s work, like Al-Azhar Park, integrates green infrastructure into urban areas.”

AKAH has been undertaking action-based research in India to explore how to reduce the urban heat island effect. It has planted about 35,000 saplings in Rajkot, Junagadh, Mumbai and Jetpur, using the fast, biodiverse, natural Miyawaki method to reafforest degraded land. Partner organisations are protecting, watering and adding to the plants, some of which have already attracted peacocks, falcons and butterflies.

AKAH has also trialled cool roof and china mosaic materials in a housing society with 3,600 residents in Kompally, Hyderabad to test solutions in a real-life scenario, using apartments with different occupancy patterns, layouts, orientations, income groups and site conditions. It partnered with the International Institute of Information Technology, Hyderabad to evaluate the outcomes. (Learn more about cool roofs in the video below)

“AKAH plans to work with the cities in Maharashtra to assess the intensity and effects of urban heat islands on communities and demonstrate further mitigation measures. We aim to build an independently-researched body of evidence to inform and strengthen AKDN Green Building Guidelines," says Prerana Langa, CEO of AKAH India.