Trends in tropical nights and their effects on mortality in Switzerland across 50 years.

Rippstein, Vanessa; de Schrijver, Evan; Eckert, Sandra; Vicedo-Cabrera, Ana M. (2023). Trends in tropical nights and their effects on mortality in Switzerland across 50 years. PLoS climate, 2(4), e0000162. Public Library of Science 10.1371/journal.pclm.0000162

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Increasing temperatures and more frequent and severe heat waves in Switzerland are leading to a larger heat-related health burden. Additionally, high nighttime temperatures or tropical nights (TNs) also affect the well-being of the population. We aimed to assess the spatiotemporal patterns in the frequency and the exposed population to TNs, and its mortality effect in Switzerland. We identified the TNs (minimum nighttime temperature >20˚C) in each district in Switzerland using population-weighted hourly temperature series (ERA5- Land reanalysis data set) between 1970–2019. We assessed the change in the frequency of TNs and the exposed population per district and decade through a spatiotemporal analysis. We then performed a case time series analysis to estimate the TN-mortality association (controlled for the daily mean temperature) by canton and for the main 8 cities using data on all-cause mortality at the district level between 1980–2018. We found an overall increase in the annual frequency of TN (from 90 to 2113 TNs per decade) and the population exposed (from 3.7 million to over 157 million population-TN per decade) in Switzerland between 1970–2019, mainly in the cities of Lausanne, Geneva, Basel, Lugano, and Zurich, and during the last two decades. The TN-mortality association was highly heterogeneous across cantons and cities. In particular, TNs were associated with an increase of 22–37% in the risk of mortality in the cantons of Vaud (Relative risk: 1.37 (95%CI:1.19–1.59)), Zurich (1.33 (0.99–1.79)), Lucerne (1.33 (0.95–1.87)) and Solothurn (1.22 (0.88–1.69)), while a negative association was observed in Ticino (0.51 (0.37–0.7)), Basel-Land (0.4 (0.24–0.65)) and Thurgau (0.65 (0.5–0.85)), and a null association in the remaining cantons. Our findings indicate that TNs are a relevant health hazard for a large part of the Swiss population leading to potentially larger impacts in the future due to climate change and increasing urbanization.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Institute of Geography > Geographies of Sustainability > Unit Land Systems and Sustainable Land Management (LS-SLM)
04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Social and Preventive Medicine (ISPM)
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geography
10 Strategic Research Centers > Centre for Development and Environment (CDE)

Graduate School:

Graduate School for Health Sciences (GHS)

UniBE Contributor:

Rippstein, Vanessa, de Schrijver, Evan, Eckert, Sandra, Vicedo Cabrera, Ana Maria


600 Technology > 610 Medicine & health
300 Social sciences, sociology & anthropology > 360 Social problems & social services
500 Science > 570 Life sciences; biology
900 History > 910 Geography & travel




Public Library of Science


[222] Horizon 2020 ; [226] Swiss School of Public Health Global P3HS


[803] Cluster: Land Resources




Melchior Peter Nussbaumer

Date Deposited:

17 Apr 2023 12:06

Last Modified:

16 May 2023 18:57

Publisher DOI:





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