Europe's population is adapting better to cold than to heat

A study led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by the "la Caixa" Foundation, has shown that Europe has adapted better to low temperatures than to high temperatures over the last two decades. The research, carried out in collaboration with the Barcelona Supercomputing Centre (BSC) and published in The Lancet Planetary Health, shows that there has been a significant decrease in cold-related mortality risk in recent years compared to the first decade of the 2000s. There has also been a reduction in the risk of heat-related deaths over this period, although to a lesser extent.

By analysing 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 in the lowest temperatures fell by 2% per year. On the other hand, the relative risk of death in the highest temperatures also decreased, but at a lower average rate of 1% per year.

New approach to account for regional differences

Traditionally, studies of this type have relied on fixed temperature thresholds to calculate risks, without taking into account that the vulnerability to identical temperatures is not the same in all parts of Europe. To overcome this limitation, the team developed a new concept: Extreme-Risk Temperature (ERT). By cross-referencing 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 took into account variations in mortality to reflect adaptations to temperature over time.

Using this methodology, the team observed that in the period 2003-2020 Europe experienced 2,07 less dangerously cold days (cold-ERT days) each year. On the contrary, the dangerously hot days (heat-ERT days) increased by 0,28 days per year.

Interestingly, not all parts of Europe were affected the same way. For example, Southeastern European regions, despite its warmer conditions, had more dangerously heat and cold days that caused a higher risk of associated mortality.

“We have become better at coping with cold temperatures over time - a process known in science as 'adaptation'.  For hot weather, people are also becoming resilient, though this improvement is less than the adaptation to cold”, says Zhao-Yue Chen, ISGlobal researcher and first author of the study.

"The vulnerability to extreme temperatures varies widely across different locations, with regions in Southern Europe being more sensitive to temperature changes than those in Northern Europe. This disparity is partially due to socioeconomic factors, including inadequate housing insulations, lower public health expenditure and limited access to social support or assistance for vulnerable populations", Zhao-Yue Chen adds.

"Our results show that, while Europe has done remarkable progress in adapting to cold, the strategies to cope with heat-related mortality have been less effective.  A 2024 survey revealed that only 20 out of 38 European countries have implemented temperature surveillance systems, and 17 countries still do not have heat-health action plans (HHAPs). Our study highlights the need for more progress in current heat adaptation measures and heat-health action plans", says Joan Ballester Claramunt, ISGlobal researcher and senior author of the study. “At the same time the observed spatial disparities underscore the need for region-specific strategies to protect vulnerable populations”, he adds.

Combined effects of temperature and air pollution

The team also looked at how often Extreme-Risk Temperatures happened on days with pollution levels above the World Health Organization (WHO) recommended limits. The co-occurrence of these two events, known as 'compound days', happened on 60% of heat-ERT days and 65% of cold-ERT days. Over time, these combination days have been decreasing except for the combination of dangerously hot days and high levels of ozone (O₃) pollution, which increased at a rate of 0.26 days per year.

Ozone is a secondary pollutant formed in the atmosphere as a result of the interaction between other gases and solar radiation. “As global warming intensifies, combined heat and ozone episodes are becoming an inevitable and pressing concern for Europe. We need to consider compound days and develop specific strategies to tackle secondary pollutants such as ozone, because the health impacts of extreme temperatures and air pollution are not completely independent. There is an interaction between them that can amplify adverse health effects," says Zhao-Yue Chen.

EARLY-ADAPT project

The study has been carried out in the context of the EARLY-ADAPT project (https://www.early-adapt.eu/), funded by the European Research Council, and aimed at studying how populations are adapting to the public health challenges triggered by climate change.

Reference

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.