Several studies suggest that global warming will lead to a decrease in mortality attributable to cold and an increase in deaths due to heat. Now, a new study by the Barcelona Institute for Global Health (ISGlobal), a centre supported by the "la Caixa" Foundation, has concluded that, if severe mitigation measures are not implemented immediately, the balance of temperature-related mortality in Europe will increase in the coming decades. According to this research, published in The Lancet Planetary Health, the decline in deaths attributable to low temperatures will not compensate for the expected increasing increase in heat-related mortality.
After analysing mortality and temperature data recorded between 1998 and 2012 in 16 European countries, the team concluded that more than 7% of all deaths recorded in this period are attributable to temperature. Cold temperatures had an impact on mortality up to ten times higher than warm temperatures.
However, projections using epidemiological modelling indicate that, if effective mitigation measures are not introduced immediately, the trend could reverse by the middle of this century, leading to a rapid increase in heat-attributable mortality.
Using data from 1998-2012 as a baseline, the team combined four climate models to make projections until the end of this century under three different scenarios based on greenhouse gas emissions.
"All the models indicate a progressive increase in temperatures and, consequently, a decrease in cold-attributable mortality and an increase in heat-attributable deaths. The difference between the scenarios is in the rate at which heat-related deaths increase", explains Èrica Martínez, researcher at ISGlobal and first author of the study. "The data point to a stabilisation and even a decrease in the total number of deaths attributable to temperatures in the coming years, followed by a very sharp increase, which could occur from the middle of the century or towards the end of this one, depending on greenhouse gas emissions", she adds.
Researcher Marcos Quijal, who shares first authorship of the study, stresses: "In recent decades, warming in Europe has occurred at a faster rate than in any other continent. The incidence of this phenomenon is uneven, with Mediterranean countries being more vulnerable than the rest. Our models also project a disproportionate increase in heat-attributable mortality in Mediterranean countries, due to a significant rise in temperatures in the summer months and this increased vulnerability to heat".
The projections indicate a very large increase in deaths due to extreme heat, to the extent that, under the highest emissions scenario without adaptation, these would exceed cold-attributable mortality.
"Our results confirm the urgency of adopting global mitigation measures, as they will not be effective if they are only adopted in specific countries or regions. Moreover, a determining factor that we have not included in our models is our capacity to adapt to new scenarios, which is already helping to reduce our vulnerability to temperatures", concludes Joan Ballester, ISGlobal researcher and last author of the study.
This research work has been carried out in the framework of EARLY-ADAPT, a project funded by the European Research Council (ERC) that analyses the environmental, socioeconomic and demographic factors involved in adaptation to climate change. EARLY-ADAPT aims to improve its projections by analysing the social factors and inequalities of climate change adaptation and including them in its climate and epidemiological models.
This is the first study in this area of research based on population-wide epidemiological data and models, and not restricted to urban populations as in previous studies. The countries analysed are: Austria, Belgium, Croatia, Czech Republic, Denmark, France, Germany, Italy, Luxembourg, Netherlands, Poland, Portugal, Slovenia, Spain, Switzerland, United Kingdom and United States.
Martínez-Solanas E, Quijal-Zamorano M, Achebak H, Petrova D, Robine JM, Herrmann FR, Rodó X, Ballester J. Projections of temperature attributable mortality in Europe: a timeseries analysis in 147 contiguous regions. The Lancet Planetary Health. 2021; 5: e446-54. https://doi.org/10.1016/S2542-5196(21)00150-9
The Barcelona Institute for Global Health (ISGlobal) is the result of an innovative alliance between the "la Caixa" Foundation and academic and governmental institutions to contribute to the efforts of the international community to address the challenges of health in a globalised world. ISGlobal consolidates a node of excellence based on research and medical care that originates in the hospital (Hospital Clínic and Parc de Salut MAR) and academic (University of Barcelona and Pompeu Fabra University) spheres. Its working model is based on the generation of scientific knowledge through Research Programmes and Groups, and its translation through the areas of Training and Analysis and Global Development. ISGlobal is accredited as a "Severo Ochoa Centre of Excellence" and is a member of the CERCA system of the Generalitat de Catalunya.