[Un article de The Conversation écrit par Elisabeth Bourgeois – Économiste, centrée sur les enjeux de climat, d’énergie et de vulnérabilités sociales, Université Savoie Mont Blanc]
To succeed in adaptation to climate change, to the image of these schoolchildren, we must see the waves of heat as a shared story, with modular actions. In this regard, there is already a decade of international research – and the experience of a few cities that have already put this work at the service of freshness.
Healthy people more likely to ignore the risks of heat
In the spring of 2025, we published an investigation, with two colleagues economists of energy, in the scientific journal CLIMATE POLICY. Three hundred French people over 55, from 13 regions, were called upon to react to two scenarios: one of five days announced at 33 ° C and, the second, from five days to 36 ° C.
They had to check, among a list of five protective gestures (drink more water, adapt your dress, take measures to best regulate the temperature of your accommodation, request external aid and seek a fresh place), those they planned to carry out.
Their answers allowed us to assess their beliefs in the probability of a heat wave and its severity for their health, as well as the nature of their emotions in the face of these scenarios.
In fact, participants saying themselves “in great shape” went on average from 3.6 gestures envisaged at 33 ° C to 1.8 gestures at 36 ° C: almost twice as much. Those who declared themselves “a little worried” followed the reverse movement: from 2.9 gestures to 4.4 (+ 52 %).
Admittedly, the exercise remains declarative: it measures intention and not action. But syntheses of social psychology show that around 40 % of the observed behaviors are shedding light on the declared intentions. In other words: when intention increases, behavior often follows – not always, but enough to guide public action wisely.
It only takes three more degrees so that the vigilance changes camp and reading the situation changes at all. These results extend those of a meta -analysis published in Nature Climate Change. Our perception of risk, our feeling of efficiency and our emotions explain almost a third of individual adaptation behaviors, even more than age or taking medication like beta-blockers!
The brain, to put it quickly, rules the thermostat of the body. It is our “inner state” that dictates for many our ability to adapt to us – and therefore, our vulnerability in the face of extreme heat.
Environment, individual and behavior: an inseparable triptych
As has been highlighted by a vast literature review published in 2019, the behaviors in the face of heat always result from the conjunction of three types of factor:
- An environmental factor (urban geometry, albedo – the ability of a surface to reflect light – air circulation, etc.),
- a personal factor (age, health, expectations, beliefs, etc.),
- And, finally, a behavioral factor (type of activity, social standards, etc.).
These three pillars are essential to take into account the diversity of individual situations.
Indicators commonly used to assess thermal comfort, the Predicted Mean Voting (PMV) and physiologically Equivalent Temperature (PET) illustrate this well: the first esteem the “average thermal vote” of a group seated in an air -conditioned office and the second translates the equivalent thermal state for an immobile individual.
Perfect indoors, these tools show their limits when applying them to a jogger, a worker or children in a school courtyard. Suffice to say that predicting the feeling of a Marseille jogger with a model developed in a Danish climate chamber would be equivalent to calibrating a submarine with an altimeter.
Why and how to adapt to climate change
The figures are stubborn and the impact of heat waves difficult to ignore. For example :
- In American schools, each day beyond 32 ° C inside causes around 1 % of the annual school program, which is reflected in the results in reading and mathematics.
- In California, studies have shown that hourly productivity decreases approximately 5 % when the maximum temperature exceeds 30 ° C, then more than 11 % beyond 38 ° C.
- Conversely, the presence of a city park will lower the ambient air temperature of about 1 ° C on average – more at night if the canopy is dense.
- In Phoenix (Arizona), a study reported a night gap of 3 to 5 ° C between wealthy and disadvantaged districts.
Adaptation therefore only makes sense if we act, at the same time, on the way in which the inhabitants read, feel and anticipate additional degrees. A green space or an air -conditioned refuge is not enough: it is still necessary that everyone knows where they are, when they open, what we find there and that we feel legitimate. This is the role of collective stories.
The return of experience of pioneer cities shows that it is possible:
- In Barcelona (Spain), more than 400 REFUGIS CLIMàTICS (shaded parks, libraries, museums, civic centers) were deployed to be accessible less than ten minutes on foot for more than 90 % of the population.
- In Valence (Spain also), a network is activated during alerts, with messages indicating the nearest place and available services (water, schedules) – an official page lists 18 shelters with addresses and schedules.
- Malmö (Sweden), for its part, has entered the increase in green spaces and taking into account vulnerabilities in its adaptation strategy.
But infrastructure is not enough. They make the gesture possible (move around, sink, slow down …), but it is first the targeted message that will provide the cognitive key to do it (“I am concerned”, “I know what to do”, “I can actually do it”).
Adaptation and public action: how to flush the bias of invulnerability
It is therefore essential to take into account elements of psychology and perception biases, mentioned above, to improve climate adaptation, and, in particular, public action in this area.
Rewrite alerts is the first evidence. Thus, general messages like “drink water” will slide on the most optimistic profiles. On the contrary, a nominative SMS recalling, for example, that a diuretic treatment triples the risk of dehydration will significantly increase the adoption of protective gestures and reduce the risk of thermal stress in the elderly.
In Finland, for example, the meteorological service publishes warnings relating to temperatures and the Finnish health and well-being institute (THL) publishes specific guides for nurseries and schools. The city of Helsinki has also evaluated the adaptation to the climate of its schools and daycares.
There remains the case for “invincible volunteers” – those who decided that they will endure the heat. There, the most effective tool is not the water cup but the autodiagnosis.
A two -minute quiz, integrated into a running app for example, could make the screen turned to red as soon as the humidx – index combining temperature and humidity – tu the danger threshold. The freedom to go running remains, but the sportsman can no longer ignore the risks.
Planting trees, finally, is useful in town to limit the island effect of urban heat (ICU), but must be done with discernment. According to the European Commission, covering 30 % of the urban surface by the foliage of the trees (canopy) would avoid more than 2,500 premature deaths in Europe each summer. But if a linden avenue Montaigne (Paris) will simply flatter Instagram, the same linden in Clichy-Sous-Bois (Seine-Saint-Denis) becomes a public health act.
These lessons will probably not be enough to tame the summer of 2050. They recall, however, that the deadly heat is not only a meteorological data, but above all a story to be rewritten constantly – with SMS, courses, QR codes on the bus shelters and trees where they count.
Back to Joliot -Curie. The students stored the thermometer and spin under the lean but tangible shadow of the young linden. The thermometer rarely ments, but our certainties can kill. Strolling them – by a well -turned message, a well -placed linden, a well -informed neighbor – is just as important as bringing the temperature to fall.
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
