High temperatures were responsible for deaths of 8,300 people in Spain last summer

Health alerts and awareness campaigns for members of the public and institutions to adopt protective measures against extreme summer heat are more than justified. Last year, high temperatures killed 8,352 people in Spain, mainly in the four months of summer, according to a study in 35 European countries carried out by the Barcelona Institute for Global Health (ISGlobal), a research centre promoted by the La Caixa Foundation, which published its results today in the prestigious scientific journal Nature Medicine.

These are not deaths directly linked to fulminant excesses of temperature, such as heat stroke or severe dehydration, which are rather sporadic ailments, but rather illnesses triggered or aggravated by extreme heat, in many cases in chronic and elderly patients, which anticipate or accelerate their death. These include hypertensive pathologies, metabolic disorders, diabetes, senile disorders, renal failure, respiratory and cardiovascular diseases.

The research points out that 99% of these annual deaths occur in the summer season in the broad sense, between 29 May and 1 October, which is becoming increasingly hot due to global warming. In fact, in last summer's two major heat waves alone, the one that melted the thermometers in mid-July and the one at the end of August, there were 4,760 deaths attributable to extreme temperatures, almost one in six (57%) of those estimated for the whole year.

But not all people are at the same risk. Researchers have found that heat-related mortality in Spanish women is 55% higher than in men and that the group most at risk by far is the over-80s, the age group with the highest death rate, up to eight times higher than that of younger retirees.

Nor are the lethal effects the same throughout the country, which is why temperature health alerts are increasingly regionalised. If the average number of deaths in Spain stands at 175 deaths per million inhabitants, the highest risk is in the Canary Islands, with particular severity in La Gomera, La Palma and El Hierro, the three islands with more than 500 deaths per million. On the mainland, the inland areas of Andalucía, Aragon and La Mancha mark the maximum, with Ciudad Real, Cordoba, Teruel and Jaen with rates above 260 deaths per million.

The team of researchers cross-referenced temperature and mortality data from 823 regions in 35 European countries, where extreme temperatures caused 47,690 deaths last year. The conclusion is that Spain has the fourth highest death rate from this cause in relation to its population. It follows Greece (393 deaths per million), Bulgaria (229) and Italy (209). If only the totals were looked at, without putting them in proportion, Spain would be the country with the second highest number of deaths in 2023, behind only Italy (12,742). The highest mortality rates are recorded in the much warmer Mediterranean area, compared to the very small effects of Denmark (32), Finland (24) or Ireland (12) and the practically non-existent effects of Sweden (1) or Iceland (zero).

Last year was the second worst heat-related mortality year in Europe in the last decade. It was overtaken by the summer of 2022, the hottest year on record, which in Spain alone is estimated to have caused 11,300 deaths. However, ISGlobal's own researchers consider their estimates of deaths to be rather conservative. They believe they underestimate heat damage because they have only weekly, not daily, records of deaths. They consider that the number of deaths in Europe in 2023 is possibly closer to 58,000 people (20% more than the certified figure), which would put the figure for Spain at 10,306 heat-related deaths.

One of the team's most encouraging findings is that improved measures against high temperatures taken in Europe over the last 20 years, by both public authorities and citizens, have reduced the number of annual deaths that could have been caused by rising temperatures by up to 80 per cent. They estimate that if the extreme temperatures in the summer of 2023 had occurred at the same time in the first five years of the century, heat-related deaths would have reached 85,000 people and would have more than doubled those recorded last year among the over-80s.

This very positive figure is due to the effectiveness of the preventive and action plans against high temperatures launched by all countries following the major death toll in the summer of 2003 (health alerts, organisation of medical resources, risk awareness campaigns, creation of climate shelters, adaptation of hospitals, centres and residences, reorganisation of working hours, etc.), better individual behaviour and socio-economic advances such as the proliferation of air conditioning, to which a third of the reduction in deaths is attributed.

However, researchers warn that the advance of extreme temperatures will get worse and very fast. By 2027, it is estimated that the entire planet will have exceeded the 1.5 degrees of global warming that the Paris Agreement considered to be a great danger. Therefore, they claim, the process of climate change must be slowed down with more ambitious and rapid cuts in CO2 emissions and by multiplying the current measures and plans for adapting to extreme temperatures.