Projection of extreme heat- and cold-related mortality in Sweden based on the spatial synoptic classification

Osvaldo Fonseca-Rodríguez; Ryan E Adams; Scott C Sheridan; Barbara Schumann

doi:10.1016/j.envres.2023.117359

Projection of extreme heat- and cold-related mortality in Sweden based on the spatial synoptic classification

Environ Res. 2023 Dec 15;239(Pt 2):117359. doi: 10.1016/j.envres.2023.117359. Epub 2023 Oct 18.

Authors

Osvaldo Fonseca-Rodríguez¹, Ryan E Adams², Scott C Sheridan², Barbara Schumann³

Affiliations

¹ Department of Epidemiology and Global Health, Umeå University, 901 87 Umeå, Sweden; Centre for Demographic and Ageing Research, Umeå University, 901 87 Umeå, Sweden. Electronic address: osvaldo.fonseca@umu.se.
² Department of Geography, Kent State University, Kent, OH 44242, USA.
³ Department of Epidemiology and Global Health, Umeå University, 901 87 Umeå, Sweden; Centre for Demographic and Ageing Research, Umeå University, 901 87 Umeå, Sweden; Department of Health and Caring Sciences, Linnaeus University, 391 82 Kalmar, Sweden.

PMID: 37863163
DOI: 10.1016/j.envres.2023.117359

Abstract

Background: Climate change is projected to result in increased heat events and decreased cold events. This will substantially impact human health, particularly when compounded with demographic change. This study employed the Spatial Synoptic Classification (SSC) to categorize daily weather into one of seven types. Here we estimated future mortality due to extremely hot and cold weather types under different climate change scenarios for one southern (Stockholm) and one northern (Jämtland) Swedish region.

Methods: Time-series Poisson regression with distributed lags was used to assess the relationship between extremely hot and cold weather events and daily deaths in the population above 65 years, with cumulative effects (6 days in summer, 28 days in winter), 1991 to 2014. A global climate model (MPI-M-MPI-ESM-LR) and two climate change scenarios (RCP 4.5 and 8.5) were used to project the occurrence of hot and cold days from 2031 to 2070. Place-specific projected mortality was calculated to derive attributable numbers and attributable fractions (AF) of heat- and cold-related deaths.

Results: In Stockholm, for the RCP 4.5 scenario, the mean number of annual deaths attributed to heat increased from 48.7 (CI 32.2-64.2; AF = 0.68%) in 2031-2040 to 90.2 (56.7-120.5; AF = 0.97%) in 2061-2070, respectively. For RCP 8.5, heat-related deaths increased more drastically from 52.1 (33.6-69.7; AF = 0.72%) to 126.4 (68.7-175.8; AF = 1.36%) between the first and the last decade. Cold-related deaths slightly increased over the projected period in both scenarios. In Jämtland, projections showed a small decrease in cold-related deaths but no change in heat-related mortality.

Conclusions: In rural northern region of Sweden, a decrease of cold-related deaths represents the dominant trend. In urban southern locations, on the other hand, an increase of heat-related mortality is to be expected. With an increasing elderly population, heat-related mortality will outweigh cold-related mortality at least under the RCP 8.5 scenario, requiring societal adaptation measures.

Keywords: Climate change; Cold; Heat; Mortality projection; Spatial synoptic classification; Sweden.

MeSH terms

Aged
Climate Change
Cold Temperature
Extreme Heat* / adverse effects
Hot Temperature
Humans
Mortality
Sweden / epidemiology
Weather