Temperature Extremes and Human Health in Cyprus: Investigating the Impact of Heat and Cold Waves

Climate change poses a substantial threat to both the Earths ecosystems and human society. InMediterranean countries like Cyprus, extreme temperatures and especially heatwaves during summermonths are increasingly common as it is observed in the past years due to anthropogenic climatechange. While cold waves are less frequent, they also pose significant health risks, as some studiesshow that more deaths actually occur during cold weather than hot, especially in warmer cities(southern) rather than colder (northern) in Europe. Extreme temperatures leads to heightenedbio-climatic stress and can adversely affect the human body, disrupting physiological functions andexacerbating preexisting health conditions, ranging from discomfort and severe illnesses that requirehospitalization to mortality.This study examines temperature trends in Cyprus over the past four decades, focusing on extremetemperature events from 2000 to 2019. Using ERA5-Land reanalysis data, we analyzed both maximumand minimum daily temperatures for both the warm (May-Oct) and the cold (Nov-Apr) season.Extreme hot days were defined as those where both maximum and minimum temperatures exceededthe 95th percentile of each month in the warm season. Conversely, extreme cold days were defined asthose where both temperatures fell below the 5th percentile in the cold season. Our analysis revealedan upward trend in temperatures over the past four decades, with a statistically significant increasein the number of extreme hot days and a decrease in extreme cold days for the last 20 years. Statisticaland machine learning methods, including Distributed Lag Models (DLMs) and GeneralizedAdditive Models (GAMs), were employed to estimate mortality and morbidity risks over a 21-day lagperiod using health statistics from Ministry of Health and Statistical Service in Cyprus. We observeda notable increase in mortality risk associated with both high and low temperatures extremes. Incontrast, the morbidity risk showed a different profile; overall morbidity risks were lower comparedto mortality and the maximum risk occurred at lower temperatures. In general, lower temperaturesexhibited pronounced health risks compared to higher temperatures. Additionally, we calculatedthe optimal temperatures that corresponded to the lower risk as well as the attributable fraction ofdeaths and hospitalizations for extreme temperature days and extreme temperature events, lastingfrom two or more consecutive days. The findings indicated that both deaths and hospitalizationswere notably higher during the cold period in comparison to the warm period. Nevertheless, duringperiods of extreme high temperatures, the rate of increase in attributable deaths was greater thanduring the cold period when compared to days with non-extreme temperatures.