A study estimates that extreme heat-related physical inactivity could cause more than half a million premature deaths annually by 2050

Extreme or prolonged heat directly affects our health, particularly because it is associated with problems of the cardiovascular system. It also has indirect effects: for example, it can disrupt basic functions such as sleep, which in turn affects both health and productivity. Heat also influences diet and our healthy habits. This study examines precisely one of these indirect effects, how heat influences sedentary behaviour, an important risk factor associated with premature mortality. The results show that, based on historical relationships between temperature and levels of physical activity, by 2050 there could be an increase of close to 10 % in deaths attributable to heat-induced sedentary behaviour, especially in more vulnerable countries with fewer resources to adapt.

These findings introduce a new dimension to climate justice, as populations with less capacity to adapt may disproportionately suffer these indirect impacts of heat. At the same time, the study opens up an important line of research and action: how to design cities and urban environments that allow people to remain physically active even in hot conditions, through solutions such as shaded spaces, green infrastructure, adapted schedules, and urban environments that reduce thermal exposure.

This is a study published in The Lancet Global Health, following a rigorous peer-review process and addressing research of high impact. The topic is particularly relevant for Spain, a country considered a hotspot in relation to the impacts of climate change, especially rising temperatures, which are the focus of this study.

Research on this topic has generally focused either on the risks and adaptation of indoor environments or on those of outdoor environments. The approach taken in this article is particularly interesting, as it assumes that adapting indoor spaces alone is not sufficient to safeguard people’s health. It also emphasises that physical exercise is a universal right and should be possible under environmentally safe conditions.

This study quantifies the health impact of physical inactivity at a global level, with varying magnitudes across regions, and highlights the need to adapt outdoor spaces. According to the study, the impact in Spain remains the same across the different scenarios considered for 2050, with a mortality ratio associated with physical inactivity of 8%, higher than that of other southern European countries such as France, Greece or Italy, at least under the less severe scenarios.

Finally, given the already warmer conditions we are experiencing, I believe that isolated climate adaptation strategies are not sufficient. Rather, starting from a detailed diagnosis, there must be a clear commitment to adaptation strategies, learning from warmer climates or from successful cases in urban settings. A strong commitment to nature-based solutions offers an opportunity with multiple co-benefits, not only in terms of adaptation to other climate change impacts but also in terms of additional health and wellbeing benefits. Possible examples range from increasing tree cover and permeable surfaces in urban areas, or renaturalising school playgrounds, to adapting riverbanks for public use, among others.