60,000 – according to the WHO, this was the number of heat-related deaths in Europe in 2022 alone. The heat island effect causes temperatures in metropolitan areas to rise to extreme levels. Not only does this heat have a negative impact on the well-being and health of city dwellers, it also effects energy consumption and of air and water quality. It is one of the biggest challenges that cities face today. If not the biggest. But the urban heat island effect is far from unstoppable. From green roofs to sponge cities to misting, in the 127th issue of topos magazine we explore how cities around the world are tackling the heat and bring you the latest approaches, innovations and projects in this battle against urban climate change.

Heat can kill in three major ways: organ failure, heart attack or kidney failure. Heat is hard work for the human body. It has to ensure that the body temperature does not rise too much, otherwise the structure of the body’s own proteins will be altered, resulting in organ and tissue damage. Humans produce sweat to counteract the damage and cool the body. What is more, the blood vessels also dilate, which in turn lowers the blood pressure, and the heart increases its pumping capacity to regulate it. This can lead to a heat stroke. If left untreated, this will lead to death.

In 2017, researchers at the University of Hawaii defined that outdoor temperatures of 37 degrees and above can be dangerous for us. In principle, however, an increased risk of death can be assumed from an outdoor temperature of 30 degrees. The tricky thing is that researchers from the Insituto de Salud Carlos III in Madrid discovered in 2017 that people die so quickly during a heatwave that they do not make it to hospital. This is why a heat warning of 72 to 48 hours in advance is so important.

In 2021, the number of heat-related deaths worldwide was 100,000. According to the WHO, the consequences of climate change are expected to claim 250,000 victims a year between 2030 and 2050. Malnutrition, malaria, diarrhoea and – heat – are cited as the cause of death. Vulnerable groups are particularly at risk from the heat – including elderly people, pregnant women and children. According to UNICEF, more than 559 million children were frequently exposed to heatwaves in 2022. By 2050, this figure is expected to rise to two billion children. Two billion, ladies and gentlemen.

The increase in extreme heatwaves is a huge problem. In May 2024, it made headlines around the world. In Tabasco, Mexico, several black howler monkeys dropped dead from the trees during a heatwave of 45 degrees. Animal welfare organizations counted 78 dead specimens of the endangered species at the end of May. In Pakistan, temperatures of up to 50 degrees were expected at the same time. Schools closed and clinics went on alert. It was the third year in a row that Pakistan experienced an unusual heatwave. And for several weeks, the officially longest heatwave in decades swept across Southeast Asia. In Thailand, at least 61 people died – more than twice as many as in the whole of 2023. In Vietnam, hundreds of thousands of dead fish floated on the surface of the Song May reservoir and in the Philippines, 53 degrees were measured in the province of Zamblas. Man-made climate change is to blame for this, exacerbated in Southeast Asia by a strong El Niño.

Due to the Heat Urban Island effect, our cities and metropolitan areas are particularly affected by the increasing heat – with far-reaching consequences: the health risks already mentioned, elevated air pollution levels, increased energy consumption, water quality issues, compromised infrastructure, reduced livability but also climate change amplification.

What I find particularly astonishing is that we as a society have been aware of the dangers of increasing heat for decades, but we are still doing far too little in terms of heat management in our cities. This is despite the fact that numerous solutions, innovations and strategies are already available. For this reason, in this issue of topos magazine, we discuss the topic of heat in the city from different angles and present current best practices – in the hope that we will finally make significant progress in climate adaptation.

Get the topos 127 – heat – here.

Our last issue is all about public mobility. How can cities solve their individual mobility problems and which innovations will provide the solutions in the field of public transportation we all are so desperately waiting for. In this issue, we take a look at cities with pioneering concepts and examine what it takes for an excellent public transport system. Read more in the editorial of topos 126 – public transport