The relative risk of death in the coldest temperatures has decreased by 2003% per year since 2, while the risk in extreme heat has decreased by only 1% per year.
A study led by the Barcelona Institute for Global Health (ISGlobal), a center funded by the La Caixa Foundation, has shown that Europe has adapted better to low temperatures than to high temperatures over the past two decades. Conducted in collaboration with the Barcelona Supercomputing Centre (BSC) and published in The Lancet Planetary Health, the study shows that the risk of death from cold has decreased significantly in recent years compared to the first decade of the 2000s. The risk of heat-related deaths has also decreased during this period, albeit to a lesser extent.
By analyzing temperature and mortality records from over 800 regions in 35 European countries for the period 2003–2020, the researchers found that the relative risk of death decreased by 2% per year at the lowest temperatures. On the other hand, the relative risk of death also decreased at the highest temperatures, but at a lower average rate of 1% per year.
New approach to take regional differences into account
Traditionally, such studies relied on fixed temperature thresholds to calculate risk, without taking into account that vulnerability to identical temperatures is not the same across Europe. To overcome this limitation, the team developed a new concept: the Extreme Risk Temperature (ERT). By comparing regional temperature and mortality data, this new approach made it possible to calculate the temperature at which the risk of death exceeds a certain threshold for each geographical area. The researchers also considered fluctuations in mortality to reflect adaptations to temperature over time.
Using this method, the team found that between 2003 and 2020, there were 2,07 fewer dangerously cold days (cold ERT days) per year in Europe. In contrast, the number of dangerously hot days (heat ERT days) increased by 0,28 days per year.
Interestingly, not all parts of Europe were affected equally. For example, in Southeastern Europe, despite warmer temperatures, there were more dangerously hot and cold days, resulting in a higher risk of death.
The team also examined the frequency of extreme temperatures occurring on days with pollutant levels above the limits recommended by the World Health Organization (WHO). The simultaneous occurrence of these two events, known as "combination days," occurred on 60% of hot ERT days and 65% of cold ERT days. Over time, the number of these combination days decreased, except for the combination of dangerously hot days and high ozone (O3) pollution, which increased by 0,26 days per year.
The study was conducted as part of the EARLY-ADAPT project ( https://www.early-adapt.eu/ ) funded by the European Research Council and aimed to investigate how the population adapts to the public health challenges caused by climate change.
Original Paper:
Zhao-Yue Chen, Hicham Achebak, Hervé Petetin, Raúl Fernando Méndez Turrubiates, Yuming Guo, Carlos Pérez García-Pando and Joan Ballester, Trends in Population Exposure to Compound Extreme-risk Temperature and Air Pollution across 35 European countries: a modeling study. The Lancet Planetary Health, 2025.
