Response of Urban Heat Stress to Heat Waves in Athens (1960–2017)

Abstract

The increasing frequency, intensity and duration of heat waves seem to follow the observed global warming in recent decades. Vulnerability to heat waves is expected to increase in urban environments mainly due to population density and the effect of the urban heat island that make cities hotter than surrounding non-urban areas. The present study focuses on a vulnerable area of the eastern Mediterranean, already characterized as a ‘hot spot’ with respect to heat-related risk and investigates the change in heat stress levels during heat wave compared to non-heat wave conditions as well as the way that heat stress levels respond to heat waves in urban, compared to non-urban, environments. The adoption of a metric accounting for both the intensity and duration of the hot event yielded a total of 46 heat wave episodes over a nearly 60-year period, but with very rare occurrence until the late 1990s and a profound increased frequency thereafter. The results reveal a difference of at least one thermal stress category between heat wave and non-heat wave periods, which is apparent across the entire range of the thermal stress distribution. The analysis demonstrates a robust intensification of nighttime heat stress conditions in urban, compared to non-urban, sites during severe heat waves. Nevertheless, severe heat waves almost equalize heat stress conditions between urban and non-urban sites during midday.

Urban Climates and Climate Change

“…Similar results were found in New York City (135). In Athens, Greece, trends in nocturnal heat stress conditions during heat waves also increase more in urban than rural environments (139) but are comparable during the day. Depietri & McPhearson (135) showed that for New York City impacts on mortality and morbidity decrease despite the increase in heat waves, probably due to an adaptation of warning systems and the development of air-conditioning.…”

Urban Heat Island and Its Interaction with Heatwaves: A Review of Studies on Mesoscale

“…UHI has enormous direct and indirect impacts on urban regions and dwellers, such as causing a considerable rise in energy consumption for cooling purposes [4,[14][15][16] and increasing heat-related mortality and morbidity, especially for vulnerable groups such as senior and low-income citizens [4,9,[17][18][19][20]. These impacts are reported to be intensified during heatwave (HW) events, a period of excessively hot days [21][22][23].…”

Spatial-Temporal Characteristics of Arctic Summer Climate Comfort Level in the Context of Regional Tourism Resources from 1979 to 2019

“…Napoli et al have assessed the thermal bioclimate of Europe for the summer season and concluded that an increase in heat stress up to 1 • C was observed from 1979 to 2016 [27]. Some scholars pointed out that southern Europe (Crete Island in Greece, Eastern Mediterranean, Athens, Madrid (Spain), Novi Sad (Vojvodina, Northern Serbia)) were under high temperature and pressure, and climate warming has led to a significant increase in the frequency and duration of high-temperature heat waves in southern Europe and a decline in climate comfort [28][29][30][31][32][33][34][35]. In central Europe, climate change has led to an increase in the number of strong and very strong heat stress days in Poland [36].…”