The heat waves of the summer of 2022 marked the minds of the French, with a month of July which was the hottest ever measured on a global scale. With a 16.7% increase in deaths and temperatures reaching over 42°C during this period, it is important to identify the most vulnerable people to face climate change and the increase in intensity. and the frequency of this phenomenon.

In this context and in the face of the latest IPCC report, which warns of the acceleration of climate change, one can wonder about the vulnerability factors faced by certain groups of the population. Some are quite obvious, such as age or location: this plays an important role in regions more exposed to extreme heat waves – such as Auvergne-Rhône-Alpes exposed to more than twenty abnormally hot days per year in during the months of June, July and August in recent years.

These are the factors that are said to be tangible, that can be measured or quantified. But other, more surprising and more intangible factors, such as mental health, are also highlighted by the economics literature.

Unsurprisingly, age plays a major role in this vulnerability: older people are of course at greater risk in the event of a heat wave. Thus, during the scorching summer of 2022, deaths increased by 20.2% among people over the age of 75 due to their frailty linked to chronic diseases.

People who say they suffer from the heat in summer often live in poorly insulated accommodation, which is difficult to ventilate, with maximum temperatures reached in summer in the accommodation exceeding 30°C – they are also victims of overcrowding.

The concept of thermal comfort takes on its full meaning. The quality of housing and the presence of comfort equipment that makes it possible to adapt to heat waves, such as air conditioning systems, will influence the degree of vulnerability of its occupants.

Data from a survey we conducted reveal that only 22.7% of households have an air conditioning system (mobile or fixed) in 2020, while seven out of ten people will be exposed to intense heat each year.

As for intangible factors, whose relationship with heat waves seems less obvious, the economic and psychological literature is increasingly focusing on the link between cognitive capacities and adaptation to extreme events. An individual’s cognitive ability will influence their decision-making and reflection process, but also their perception of certain situations and their ability to adopt appropriate behaviors.

By generating a feeling of pessimism, powerlessness and fatality with regard to their life and their future, people in a state of depression will both restrict their adaptation to heat waves and thus increase their vulnerability. This point is all the more important as the cognitive abilities of individuals decline with age and currently nearly one in five people have suffered or will suffer from depression in their lifetime.

Moreover, in this context where adaptation will be a tool to deal with one’s vulnerability, the question of the accentuation of inequalities arises. Whether through the thermal renovation of one’s home, the acquisition of an air conditioning system or by increasing one’s energy bill to cool down, the gap with the most modest households will widen.

The cost of this adaptation will not be within the reach of all households and will leave some households in critical situations where they will be greatly exposed to the health consequences of heat waves. There are thus discrepancies according to income quintiles and rates of household equipment to deal with climate change. The conclusion is clear: the wealthiest households will be better able to cope with extreme heat waves.

*Dorothée Charlier is a lecturer in Energy and Environmental Economics at the AE (Institute of Business Administration) Savoie Mont Blanc; Margot Zambon, intern at IAE/Irege, contributed to the writing of this article.

**This article is republished from The Conversation under a Creative Commons license. Read the original article.