Ms Kavethiya’s battle with the rising heat mirrors the struggle of hundreds of millions of people across the region who face rising temperatures caused by climate change and the heat trapped in ever-expanding cities. They face other perils, too, such as rising sea levels, worsening floods and storms and, in some places, wildfires.

To survive these threats, cities must adapt. And the good news is that despite the gloomy predictions about the future, ordinary people, grassroots groups and governments are starting to act and in so doing, creating a safer future.

Cities are usually warmer than their surrounding areas due to factors that trap and release heat

“Grassroots (activity) is a critical ingredient for successful climate adaptation to happen,” said professor of urban climate at Singapore Management University Winston Chow.

Urban residents are at the front line of climate-driven hazards, and communities also can provide essential local knowledge to enhance the effectiveness of resources deployed to reduce climate risk.

The ongoing heatwave in South-east Asia and floods in southern China as well as the deadly floods in Dubai are the types of growing risks cities face, said Prof Chow. He is also co-chair of the United Nations Intergovernmental Panel on Climate Change Working Group II, which studies climate change impacts, adaptation and vulnerability.

More than half of humanity now lives in cities and this will rise to about 70 per cent by 2050, the United Nations says.

By the middle of the century, nearly 1,000 cities globally – from about 350 cities now – will see their average high temperatures reach or exceed 35 deg C during summer months, according to C40, a global network of nearly 100 mayors of the world’s major cities who are working to tackle climate change.

This will increase the risks of heat stress and heat-related illnesses, such as heart disease, especially for the urban poor who must work outdoors and also cannot afford cooling appliances at their homes. Heat is already a top cause of death from natural disasters, such as heatwaves, in rich and poor nations.

Densely packed cities also absorb the sun’s heat more, further pushing up temperatures. That is certainly the case with Ahmedabad, a city of eight million people in Gujarat state. A 2022 study found that urban areas of Ahmedabad are 3 deg C to 4 deg C warmer than the adjacent rural areas.

Faced with so many climate-linked threats, Asia-Pacific’s megacities are employing a range of strategies. These range from very simple projects, such as planting more trees, creating more green spaces and painting the roofs of homes and commercial buildings white, to complex engineering ones, such as sea walls, subway flood barriers and deep drainage networks.

On April 4, the afternoon temperature outside was 41.3 deg C, but inside her home it was a more tolerable 38.9 deg C. “I am thinking, this summer, I will get some relief,” she said, hoping to put in additional work and earn more money.

While it costs around 30 rupees to paint one square foot with the reflective paint, Ms Kavethiya’s household and about 160 others in Ahmedabad’s Koyli Talav neighbourhood were given the paint for free by Mahila Housing Trust, an Ahmedabad-based non-profit that seeks to improve living conditions for poor urban communities.

The organisation has so far deployed around 10,000 such “cool roofs” across the country. It is a low-carbon, low-cost cooling solution for India’s less privileged communities who, despite being highly exposed to heat stress, cannot afford cooling appliances such as air-conditioners.

“These people have to cool down somehow,” said Dr Dileep Mavalankar, the former director of Indian Institute of Public Health Gandhinagar in Gujarat’s capital city Gandhinagar. “And this white paint is one of the cheaper options. Plus, it is passive, it does not require any electricity,” he added.

Here’s how the cooling initiatives have helped residents in Ahmedabad.

The paint could prove to be a key option for the poor as summers in India become more brutal. The year 2023 ended as the second-warmest for India since record-keeping began in 1901.

India’s meteorological department has already predicted that most of the country could be hit with above-normal temperatures and heatwaves during summer from April to June.

Low-income Indian neighbourhoods often face issues that aggravate heat-related stress. These include overcrowding, cheek-by-jowl construction that impedes ventilation and the use of cheap roofing materials that trap heat.

This can cause both short-term health problems such as heat-related fainting – which Ms Kavethiya suffered from – and long-term ones such as cardiovascular disease.

Heat stress also reduces earnings. The latest Lancet Countdown on health and climate change estimates India lost 191 billion potential labour hours due to heat exposure in 2022. This potentially amounts to an income loss of US$219 billion (S$295 billion) in 2022, equivalent to 6.3 per cent of India’s gross domestic product.

In 2010, Ahmedabad experienced one of its worst heatwaves, leading to an additional 1,344 deaths in May that year compared with the mean of figures from corresponding periods in May 2009 and 2011. Reasons for these additional deaths included heat-induced dehydration, cardiac disease and respiratory issues. This sudden surge in fatalities compelled the authorities to work on a heat action plan, which was launched in 2013 to reduce deaths from heat-related stress.

The plan, the first such initiative in South Asia, includes a colour-coded early warning heat alert system for the city’s officials. This sets in motion wide-ranging measures, such as strategically deployed ambulances, the delivery of drinking water to poorer areas, and the distribution of public awareness materials to teach residents how to cope with heat stress.

Cold drinking water dispensing stations and oral rehydration corners are some of the other initiatives put in place

An estimated 1,190 deaths have been prevented each year since the heat action plan was put in place.

Mahila Housing Trust is trying to partner with more local municipal bodies and corporates to support a wider roll-out of its cool roofs across the nation, a step that could save more lives.

Communities are tackling this, for instance, by creating cool zones, using special paints on roads and pavements, and making better use of green spaces.

In western Sydney, temperatures can exceed 40 deg C in summer, far hotter than the coastal eastern parts of the city 20km or more away. It does not help that swathes of western Sydney’s more rapidly growing suburbia also have dark roofs and less greenery, although local councils are trying to address the situation.

Sweltering Cities, an Australian not-for-profit formed in 2020, works with communities across Australia to advocate for community-based solutions to rising suburban temperatures. It has led a campaign for sheltered bus stops in western Sydney and is pushing for a ban on dark roofs, which cause hotter homes by trapping heat rather than reflecting it.

Ms Emma Bacon, the organisation’s founder and executive director, told The Straits Times the group formed after it became clear a growing number of residents in western Sydney reported they could not walk down the streets due to the heat or could not take their children to the playground because of a lack of shade.

“We have these large suburban areas with hardly any trees, lots of concrete, and new developments with no space on the street for trees,” she said.

Often people feel the heat is an individual problem. But these are problems that affect hundreds of thousands or millions of people at once. There needs to be a community voice for finding solutions.

One project holds the promise of a network of cooling parks, helped by artificial intelligence (AI) controlling an irrigation system.

During a hot, early autumn day at Bicentennial Park in western Sydney on April 7, the afternoon sun was blazing, but finding the coolest spot in the park was refreshingly simple.

This 42ha park, billed as the world’s largest data-based urban cooling project, has an app that indicates, in real-time, the hottest and coolest spots there.

On April 7, the coolest spot – at 26.4 deg C – was a large, shady patch of grass, surrounded by a circle of native vegetation and fanned by a gentle breeze. The hottest spot, closer to 28 deg C, was about a kilometre away, on an exposed hillside that faced the sun.

In reality, the difference in heat between the two spots seemed much starker, because the app is based on air temperature rather than the “feels like” temperature, which also takes into account humidity, solar radiation and wind.

But this park does much more than guide visitors to the coolest spot for a picnic. Its main role is to use technology to keep the park’s temperatures as cool as possible and to push cooler air into the surrounding high-density residential and business areas.

The director of the project, Professor Sebastian Pfautsch, told ST that increased urban development and climate change were causing sharp rises in temperatures in western Sydney.

The aim of the park project was to adapt to this heat by “turning the park into a natural air-conditioning system”, said the professor of urban planning and management at Western Sydney University.

In this densely populated part of Australia, you cannot mitigate the heat, but you can adapt.

The project, known as SIMPaCT (Smart Irrigation Management for Parks and Cool Towns), uses AI and smart technology to monitor temperatures and weather conditions to direct the park’s irrigation. It relies on soil moisture and air temperature data collected from 50 temperature and humidity sensors, 200 soil devices, and 13 weather stations scattered throughout the park.

Infrared data showed that areas with more trees were cooler...

...while areas closer to buildings were warmer even if there were trees.

The data is then applied to a digital model of the park, which considers its undulations, vegetation and surface types, as well as official weather forecasts, to determine how and where to provide irrigation across the park’s 200 irrigation zones. The park’s irrigation algorithm is constantly incorporating data on how previous irrigation methods have fared.

We store data about decisions made in the past, so the algorithm can learn from its decisions about the best ways to irrigate the park and keep a threshold of soil moisture.

“Normally, in extreme weather, plants and trees don’t have enough water and basically shut down. We hydrate them so that they transpire at maximum rates to cool the park at the maximum level possible.”

Transpiration, the evaporation of water from a plant, can help cool the surrounding environment. As the moisture evaporates from the leaves, heat is removed from the air, providing a cooling effect.

Prof Pfautsch added: “Cool air also travels downwind, and this cools the surrounding area and reduces the electricity demand.”

The park is estimated to be able to send air that is 3 deg C to 4 deg C cooler than surrounding temperatures about 600m into the neighbouring residential and business districts.

The project is crucial for an area such as western Sydney.

Residents in Sydney’s western area are particularly vulnerable. The area has a fast-growing population – which is due to grow from 2.7 million today to 3.2 million by 2036 – but already experiences temperatures about 6 deg C to 10 deg C higher than coastal suburbs during heatwaves.

The western region of Greater Sydney experiences a higher number of hotter days compared with the city

Though Australia is known for its disasters such as bushfires, floods and drought, more residents die from heatwaves than any other natural hazard. About 700 people are hospitalised and 29 die each year from heat-related conditions such as cardiac arrest or organ damage.

According to a report released in March by the Committee for Sydney, heatwaves cost western Sydney’s businesses and residents A$1.4 billion (S$1.25 billion) a year, based on extra cooling costs, productivity losses and health costs, and this amount is due to rise to A$6.8 billion by the 2070s.

Local councils, and the state and federal governments have been trying to tackle the problem by supporting projects such as SIMPaCT, which has cost almost A$4 million.

Tokyo is heating up. In 2023, Tokyo’s average daily temperature hit a record high at 17.6 deg C.

The capital sweltered in 2023 with a record 90 days above 30 deg C, including 22 “extremely hot days” at above 35 deg C

Mr Toshifumi Fukuyasu of the Tokyo Metropolitan Government’s (TMG) Bureau of Environment said the government was subsidising the installation of “cool spots” such as water coolers and mist-spraying stations in public spaces, and promoting more greenery, including on rooftops and walls.

Another measure is to embed heat-blocking innovation in pavements and roads.

There are two main methods: either by coating them in a special material that can effectively reduce surface temperatures by up to 8 deg C, or by embedding water-retaining material that can reduce temperatures by up to 10 deg C.

The solar heat-blocking pavement has a coating that can reflect infrared radiation using a mixture of heat-reflecting pigment and hollow ceramic microspheres. The water-retaining pavement uses a porous asphalt mixture with the gaps filled with a water-retaining material. The evaporation of water curbs the rise of pavement temperatures.

About 190km of roads under TMG’s purview had the heat-resistant coating as at March 2024, with a total of 245km to be coated by 2030. Another 21km of roads had the water-retention feature as at March 2023.

The method involving water-retaining material has more drawbacks, however.

“The temperature is lowered when water evaporates, but it won’t work unless we use sprinklers or if it rains for a while,” said Mr Shinji Wada of the TMG’s Bureau of Construction. Such roads also tend to be less effective in mitigating noise.

The heat-blocking coating requires no maintenance work such as water-spraying and has the added advantage of reducing road wear by traffic, he noted.

Singapore has invested heavily in expanding and deepening its drainage network, for instance, by building more flood retention tanks and tunnels. And it has raised the minimum height of reclaimed land.

It recently mapped out how to protect the East Coast area from sea levels that could increase by a metre by the end of this century – by reclaiming three tracts of land off East Coast Park in the Long Island project.

Reclaimed land and tidal gates would protect a large stretch of coastline and, in addition, create a reservoir. Around 20km of new coastal and reservoir parks could be added.

It is all part of the city’s broader strategy to adapt to climate threats, and plans have continually been adjusted as the challenges become better understood.

Tokyo has also taken steps to reduce flood risks.

On March 28, TMG revised its climate change adaptation plan, enacted in 2021, as it observed an increase in short-term but intense rainfall and record-breaking heat conditions.

This complements the Tokyo Resilience Project, which has 17 trillion yen (S$151 billion) worth of infrastructure upgrades planned over the next two decades.

The amount includes 7.1 trillion yen for measures against flooding caused by stronger typhoons, as well as tsunamis triggered by earthquakes.

The TMG is raising river and coastal embankments, and expanding its intricate cavern of underground water reservoirs that temporarily store flood waters.

It is also fortifying its extensive subway network and sewerage system against flooding – everyday infrastructure that many take for granted.

Underground spaces such as subway stations flood faster than above ground and, once flooding begins, water rushes in all at once. This makes it difficult for passengers to evacuate.

The TMG manages the Toei Subway, which consists of 106 stations across four lines and had an average of 2.24 million users per day in 2022, but is also working with other railway operators like the Tokyo Metro on disaster mitigation measures.

Among the first lines of defence are water-stop plates and/or waterproof doors at station entrances and exits, while remote-controlled flood-prevention devices are installed at ventilation openings to stop water from rushing in.

The goal is to complete work on the entrances at seven stations and ventilation openings of 20 stations by March 2025 on the Toei Subway. By the 2040s, the entrances and ventilation openings of 65 stations will be protected, while watertight gates will be in place at seven locations.

Elsewhere, the TMG is also building new trunk sewers in the wastewater collection system to increase stormwater drainage capacity, using the revised hazard maps and flooding run-off analyses.

“Imagine if your toilet becomes unusable, or if the sewage pumps are damaged by flooding and unprocessed water flows back to the surface,” says Mr Takashi Abe of the TMG’s Bureau of Sewerage.

If sewerage facilities are flooded due to flood damage and sewerage functions are lost, it will have a significant impact.

Watertight gates are being installed at sewerage plants across Tokyo that altogether process 5.5 million cubic metres of water per day, to protect their electrical systems, and water pumping and disinfection functions. There is one at the Nakagawa Sewage Treatment Plant that is deemed high-risk as it is located near four rivers.

Tokyo has a network of underground regulating reservoirs to control the flow of water into the river during torrential rain

Across the region, much more needs to be done to dial back the risks from increasingly severe climate change. While the technology and resolve exist to make cities more resilient, the risks are growing for those who fail to act.

“Global temperatures are not going to decrease any time soon, and climate-driven hazards will very likely become more frequent and intense,” said Prof Chow. “When these events hit fast-growing but unprepared cities in the region, the impacts to vulnerable populations and key infrastructure in cities will be severe.”

“In an increasingly climate-disrupted world, city leaders who fail to prepare should prepare to fail,” he said.