Climate-associated human health effects

Abstract

The intensifying impacts of climate change on human health represent a significant and pressing global health threat of the current century. This encompasses both short and long-term effects on human health, as well as ecosystem changes linked to rapid shifts in climate, and the subsequent spread of vector-borne diseases. The complex interplay between climatic factors, socioeconomic variables, and health outcomes poses significant challenges for contemporary studies. Moreover, investigations into climate-associated health burdens in historical times are constrained by the paucity of extensive datasets.

This dissertation explores the spatial and temporal patterns of health impacts in response to climatic variability during the late pre-industrial era (here, 1749－1859) in the Nordic region including Denmark, Sweden, and Finland. The primary dataset used in this dissertation comprises malaria data (cases and deaths) and all-cause deaths obtained from parish-level vital statistics for the period of 1749 to 1859. To investigate the association between climate and malaria, the distributed lag non-linear model (DLNM) was applied to capture nonlinearity and lag effects of time-varying environmental exposures on malaria risk in Denmark, Sweden, and Finland. Additionally, a spatiotemporal analysis was conducted to explore the climate－mortality relationship in Sweden. This analysis involved comparing excess mortality with gridded climate datasets.

Results from this dissertation present historical evidence of the significant impacts of climate-related changes on both malaria and mortality in temperate regions like the Nordic countries. The analysis demonstrates the influence of temperature, precipitation, and sea-level change on malaria risk, as well as the seasonal association between climate and mortality levels. Moreover, this work identifies diverse lag effects of climate impacts on mortality across different geographical areas in Sweden. These findings underscore the relevance of climate factors in comprehending infectious diseases and mortality dynamics during the pre-industrial era in the Nordic region. By enhancing our understanding of the historical association between climate and health outcomes, this dissertation contributes valuable insights to inform future strategies for mitigating the current and future health risks associated with climate change.