Spatiotemporal characteristics of human thermal comfort across southern Africa: An analysis of the Universal Thermal Climate Index for 1971–2021

Abstract

The 6th Assessment of the Intergovernmental Panel on Climate Change projects increasing thermal-associated morbidity and mortality under anthropogenically induced warming. Over 100 indices exist to quantify thermal stress, and among these, the Universal Thermal Climate Index (UTCI) was developed for regional investigations of thermal stress influences on human health. Although by definition a universal index, current applications are mainly limited to Europe. For regions such as Africa, use of the UTCI has been hampered by a lack of available requisite input variables from ground-based meteorological stations. To overcome this, a gridded dataset, derived from ERA5 reanalysis, of UTCI equivalent temperatures was developed by the European Centre for Medium-Range Weather Forecasts. Using this dataset for daily average, minimum and maximum UTCI values, we explore spatiotemporal patterns and changes thereof over annual, seasonal, and monthly scales across southern Africa from 1979 to 2021. Across these scales, 9 of 10 UTCI thermal stress categories were observed, ranging from very strong cold stress to extreme heat stress. Spatially, no thermal stress was most widespread for daily mean values, whereas for daily maximum (minimum) values there was a wider heat (cold) stress incidence, with frequent occurrences of moderate and strong heat stress (slight and moderate cold stress). Interannually, a clear El Niño-Southern Oscillation influence on thermal stress was evident during summer, with El Niño (La Niña) phases extending (reducing) heat stress incidences by up to 13.8% (2.9%). Over the study period, heat stress increased at statistically significant rates in many instances, with the strongest, most widespread increases, for the daily average and maximum (minimum), during spring (summer), averaging 0.28 and 0.29 CÁdecade −1 (0.23 CÁdecade −1 ); few regions experienced statistically significant decreasing trends. Overall, the trend results highlight regions vulnerable to significant thermal climate changes, and thus should be considered in decision-making regarding outdoor activities.

Spatial–Temporal Characteristics of Human Thermal Comfort in Xinjiang: Based on the Universal Thermal Climate Index from 1981 to 2019

“…In Africa, Sarah found a wide range of thermal stress experienced, ranging from very strong cold stress to extreme heat stress in southern Africa. The study also noted a significant increase in UTCI with a rate of 0.28 • C decade −1 [27]. Similarly, research by Mohammed in North Africa and the Middle East found UTCI values ranging from 0 • C to 32 • C, with an increasing trend of 0.1 • C to 0.7 • C decade −1 [28].…”

Variability of air quality and bioclimatic conditions in urban area: Case study of Lublin

“…In recent years, it has been used by among others Di Napoli et al (2018) for selected European countries, Nemeth (2011) in Hungary, Pecelj et al (2021) in Serbia, Nastos and Matzarakis (2012) in Greece, Urban and Kyselý (2014) in Czechia and Burkart et al (2016) in Portugal. Outside Europe, UTCI has been applied among others in Brazil , India (Dash et al 2017), Japan (Ohashi et al 2018) and China (Ge et al 2016), as well as Iran (Baghideh et al 2016, Roshan et al 2018), South Africa (Roffe et al 2023) and China (Lin et al 2022).…”

Increasing Trends of Heat Waves and Tropical Nights in Coastal Regions (The Case Study of Lithuania Seaside Cities)

“…Over the past century, more than 100 indices have been developed and used to assess bioclimatic conditions for human beings [25]. For example, according to the universal thermal climate index (UTCI) used in Europe, there is no heat stress for humans in the range between +9 • C and +26 • C, moderate heat stress ranges from +26 • C to +32 • C, and strong heat stress ranges from +32 • C to +38 • C [26]. The effective temperature index was established to provide a method of determining the relative effects of air temperature and humidity on comfort [25].…”