Projection of temperature-related total and cardiovascular mortality under different climate and population scenarios by the end of the 21st century in Bavaria, Germany

Abstract

Background: Global warming is anticipated to result in larger heat- but less cold-related mortality. Thus, it remains unclear whether the net temperature-related mortality burden will increase in the future. We aimed to project the heat-, cold-, and net temperature-related total and cardiovascular mortality across five Bavarian districts. Methods: We applied location- and age-specific exposure-response functions (ERFs) to project temperature-related mortality during the future period 2083-2099 compared to the baseline period 1990-2006 under combinations of five climate (constant climate, Representative Concentration Pathway [RCP]2.6, RCP4.5, RCP6.0, RCP8.5) and six population scenarios(constant population, Shared Socioeconomic Pathway [SSP]1, SSP2, SSP3, SSP4, SSP5) assuming no adaptation. We further performed projections using location-specific overall all-age ERFs.Results: The net temperature-related mortality increased under most scenarios with the highest increment under SSP5-RCP8.5 by 19.61% (95% empirical CI(eCI): 11.78, 30.91) for total and 11.24% (95%eCI: 1.04, 23.29) for cardiovascular mortality. When considering the age-effect and population aging, even under a favourable SSP2-RCP2.6 scenario, the net-mortality increased by 9.33% (95%eCI: 5.94, 12.76). In contrast, when not accounted for, net-mortality decreased by 0.23% (95%eCI: -0.64, 0.14). This was similarly observed for cardiovascular mortality. Furthermore, the climate-only effect was inconsiderable, whereas the population-only effect showed a high, up to 17.35% (95%eCI: 11.46, 22.70) increment in total deaths. Likewise, the increments in cardiovascular mortality under SSP5-constant climate (11.47% (95%eCI: 2.58, 19.57)) and SSP5-RCP8.5 (11.24% (95%eCI: 1.04, 23.29)) were similar.Conclusion: The elderly population, highly vulnerable to both heat and cold, is projected to be about four folds the younger population. Thus, the combined effect of global warming and population aging contributed to a projected increase in temperature-related total and cardiovascular deaths for all SSP-RCP scenarios. The population-effect dominated the climate-effect. Mitigation, age- and cause-specific adaptation strategies targeting the vulnerable groups might greatly reduce the future temperature-related mortality burden.