Extreme heat is no longer a problem of the future, Tara van Iersel and Josine van den Bogaard of the Rotterdam HeatLab say. We spoke with them about Rotterdam’s heat policy.

As the climate changes, we are increasingly confronted with extreme heat. Cities and their residents are hit hard: health, liveability and equality are all under pressure as a result of heat stress. But heat policy in the Netherlands is still relatively undeveloped.

In Rotterdam, the municipality, the public health service and knowledge institutions have therefore joined forces in the HeatLab, where practice and science come together to work on a heat-resilient city.

Tara van Iersel (Heat and Drought Adviser at the Municipality of Rotterdam) and Josine van den Bogaard (Senior Policy Adviser at GGD Rotterdam-Rijnmond) have been partners in the HeatLab since its foundation. In the run-up to the 2026 Heat Action Day, we sat down with them for a conversation.

Why is it important for cities to start taking heat policy seriously?

Tara: “The main reason, of course, is climate change: it is getting hotter, and hot periods are becoming more frequent. That has consequences for health, liveability, public space and nature.

In Rotterdam, we really began working on our heat approach in 2019, through Rotterdams Weerwoord. There was already an urgency document at that time. And that sense of urgency has only grown. Climate inequality, for example, is a major issue: if you do nothing, disparities will increase. At the same time, the city continues to grow. More and more is being built, which means the city is becoming increasingly paved over. That, in turn, creates even more heat.”

Josine: “Heat is no longer a problem for the future. We are seeing heatwaves last longer and become more intense, and we can also see very clearly that the consequences are genuinely worrying. The Netherlands Environmental Assessment Agency does not call heat one of the greatest climate threats facing the Netherlands for nothing. On 25 July 2019, the hottest day ever recorded in the Netherlands occurred. The number of deaths one day later was higher than ever recorded on a summer’s day.

With climate disasters such as a forest fire or a flood, the scale of the damage is immediately visible. With extreme heat, the damage is less visible. It is more about major effects on health, and with that, pressure on the healthcare system. Another factor is that people are living longer and remaining in their own homes for longer. That makes older people more vulnerable.”

Why is heat not only a municipal issue? Why are scientists, healthcare institutions, residents and other parties working together on solutions?

Josine: “Heat affects so many different issues at once. That means you have to work together.

As a public health service, you are very much rooted in day-to-day practice, but you cannot do without scientific knowledge. With the Heat Lab, we connect practice and research. And that is not a one-way street: questions from practice reach researchers, and researchers in turn can learn from practice and experiment within it.”

Tara: “Heat is also still a fairly new topic within municipalities. We need knowledge from outside. At the same time, budgets are not unlimited. Collaboration helps make research possible that aligns with questions arising in practice.”

Josine: “What also helps is that we work locally. You get to know each other quickly and can easily think together about specific places or projects. That makes the collaboration strong.”

Heat can sometimes sound like a complicated issue. Is it?

Josine: “Actually, not all that much. We already know a great deal: that shade helps, that greenery helps, and how to ensure buildings retain less heat. The main thing is that we start taking it seriously. Heat is sometimes underestimated. People think: well, we know what warm weather is. But in the future we will be facing heat that is unprecedented for us, and that we will find very difficult to cope with.”

Tara: “Of course, we still have many knowledge questions, but the complexity often lies more in the practical organisation. Who is responsible for tackling heat? The municipality, for example, is responsible for public space, but much of the property in the city does not belong to us. Healthcare organisations, housing associations and residents all have a role to play as well.”

Josine: “And many measures are still voluntary. There are few rules or standards. That gives those responsible less guidance and makes financing difficult, for example.”

Why is Rotterdam, in particular, a city where so much is happening around heat and heat resilience?

Josine: “Rotterdam does have something of a roll-up-your-sleeves mentality. The lines of communication are short, and there is a great willingness to work together.”

Tara: “And there is room to experiment. For instance, with pilots for shade cloths in the city. Not everything has to be completely certain in advance. You are allowed to try things, even if you do not yet know exactly how they will turn out.”

Josine: “Yes, that really helps.”

Tara: “Rotterdam is also home to many people with roots in warmer countries. There is a lot of knowledge and experience there about dealing with heat, and we could make more use of that here.”

When, in your view, has heat policy succeeded?

Tara: “When heat resilience is a natural part of everything we do. In other words, when we no longer have to think about heat policy separately, because heat and cooling are automatically considered in every project and every decision.”

Josine: “We are not there yet, and major tasks still lie ahead. But we do not have to reinvent the wheel completely. We already know a lot. Now we mainly have to get on with it. Or, as they say in Rotterdam: niet lullen, maar poetsen. Less talk, more action.”