Harvesting Effect and Extreme Temperature-Related Mortality in Italy

Vinod Joseph Kannankeril Joseph, Department of Statistical Sciences - University of Bologna
Risto Conte Keivabu, Max Planck Institute for Demographic Research (MPIDR)
Raya Muttarak, University of Bologna
Emilio Zagheni, Max Planck Institute for Demographic Research (MPIDR)
Stefano Mazzuco, University of Padova

One substantial direct impact of climate change on human health and mortality stems from extreme temperatures. In this study, we explore the phenomenon known as the “harvesting effect”, expecting an effect modification of previous winter mortality on the relationship between temperature and mortality in the following summer and vice versa. We combine mortality data from the ISTAT with temperature data from E-OBS for Italy at the provincial level from 2011 to 2019. Poisson regression models are employed to estimate the effects of temperature extremes on mortality among individuals aged 60 and above. The temperatures below and above the comfort zone are associated with an increased monthly mortality rate, with a more robust and pronounced effect size observed in the most extreme temperature bins. Considering the harvesting effect, the results suggest significantly lower effects of warm days (= 85th to < 95th percentile) and hot days (>95th percentile) following winters with higher mortality. We observe the impact of hot days and in particular the described harvesting effect to be stronger for individuals 80+. The results highlight how the increase of vulnerable individuals due to low winter mortality could increase the impacts of heatwaves on the population and for individuals 80+.

Keywords: Mortality and Longevity, Population, Environment, and Climate Change

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