Call it overheating

Indeed, in a warming scenario – perhaps the most appropriate expression here is really overheating – the risk of drought increases, the risk of forest fires increases, the risk of illness and death increases.

According to estimates by the European Environment Agency, by 2100, if nothing is done, we will experience an annual excess of more than 90,000 European deaths due to heat waves.

Sixty percent of the world population will live in cities.

Even in this scenario of overheating, cities assume particular prominence.

According to the United Nations, currently, the population living in cities is greater than the population living in rural areas, and it is expected that, in the next 50 years, it will reach 60% of the world's population. However, cities account for only 3% of the physical space, which means that the trend is for increasingly denser cities, from a population point of view.

Cities are also responsible for the consumption of 80% of all energy produced and for 75% of greenhouse gas emissions. Inevitably, the fight against climate change will be won or lost in cities.

A correlation with antisocial behavior

The risks of the overheating of cities are already well known, and many of them are already quantified. There are direct and indirect risks, to health, the economy, work, justice, education, social and territorial cohesion, biodiversity, etc.

There are, however, other less obvious risks. One of them has to do with the possible effects of rising temperatures on hate speech, harassment, and voluntary homicide, resulting, therefore, in a risk of increased social conflicts.

On days when the temperature exceeded 32.2 °C, harassing behavior increased by 5%.

A researcher of the Potsdam Institute for Climate Research Annika Stabmesser, in 2022, published a study in which she analyzed more than 4 billion tweets using machine learning.

Her conclusion: in situations where the temperature reached extreme values, that is, between 42ºC and 45ºC, the prevalence of tweets that included hate speech increased by 22%, when compared to tweets that were made in a context of moderate temperature.

Harvard University researcher Ayushi Narayan, a specialist in labor economics, also conducted a study in which she evaluated the correlation between heat and discriminatory and harassing behavior in the workplace, using a sample of postal service workers in the United States.

On days when the temperature exceeded 32.2 °C, harassing behavior increased by 5%.

The association between heat and cases of voluntary homicide has also been studied in cities including Chicago and New York: an increase of 5ºC in the average daily temperature corresponded to an increase of 9.5% and 8.8%, respectively, conclude the authors of this study.

Why does this happen?

Several theories have been proposed to explain the relationship between heat and antisocial behavior.

One of them, of a biological nature, proposes that an increase in temperature increases discomfort, frustration, impulsivity and aggression, in addition to interfering with cognitive abilities. In the case of indoor environments without cooling, these effects end up being exacerbated, which may lead to aggressive behavior, both physical and verbal, online and in real life.

Today, climate change adaptation plans in cities cannot ignore the effects of temperature on citizen behavior.

In ever denser, ever hotter cities, the risk of aggressive behavior between people is not a negligible risk, even if it can be subtle. By the way, a good example of this subtlety is perhaps what happened in two recent hearings of the Parliamentary Committee of Inquiry in Portugal. In a room susceptible to heat, there were a lot of complaints that the air conditioning was not working properly. In this context, an air conditioner is much more than an air conditioner; it will perhaps be a containment device. In other words, cooler. Cities, too, need these cooling devices, precisely so that, when they ignite, they prevent the conflagration.