Spatial and temporal changes of outdoor thermal stress: influence of urban land cover types

Abstract

Green infrastructure (GI) has emerged as a feasible strategy for promoting adaptive capacities of cities to climate change by alleviating urban heat island (UHI) and thus heat stress for humans. However, GI can also intensify the winter cold stress. To understand the extent of UHI within a city as well as the link between outdoor thermal stress both diurnally and seasonally, we carried out an empirical study in Würzburg, Germany from 2018 to 2020. At sub-urban sites, relative humidity and wind speed (WS) was considerably higher and air temperature (AT) lower compared to the inner city sites. Mean AT of inner city sites were higher by 1.3 °C during summer and 5 °C during winter compared to sub-urban sites. The magnitude followed the spatial land use patterns, in particular the amount of buildings. Consequently, out of 97 hot days (AT > 30 °C) in 3 years, 9 days above the extreme threshold of wet bulb globe temperature of 35 °C were recorded at a centre location compared to none at a sub-urban site. Extreme heat stress could be halved with 30–40% cover of greenspaces including grass lawns, green roofs, and green walls with little compromise in increasing winter cold stress.

Biosphere functional integrity for people and Planet

“…For recreation in urban ecosystems, the minimum amount of green space under different forms and quality, as well as its spatial configuration or linear distance (see Table 1) from each neighbourhood has been assessed from several studies. For example, these studies analysed the relationship between the amount of green space in each neighbourhood in cities and peoples’ mental and physical well-being, measured by psychological distress level, number of natural-cause mortality, cortisol levels, prescriptions for antidepressants, presence of anxiety, COVID-19 incidence rate and heat stress level 45–47 .…”

“…For recreation in urban ecosystems, the minimum amount of green space under different forms and quality, as well as its spatial configuration or linear distance (see Table 1) from each neighbourhood has been assessed from several studies. For example, these studies analysed the relationship between the amount of green space in each neighbourhood in cities and peoples' mental and physical well-being, measured by psychological distress level, number of natural-cause mortality, cortisol levels, prescriptions for antidepressants, presence of anxiety, COVID-19 incidence rate and heat stress level [45][46][47] . For soil protection and water quality, the soil loss reduction efficiency of vegetative and/or buffer effectiveness or pollutants reduction capacity, respectively, have been considered as a baseline to estimate the minimum vegetation cover and buffer width needed to maintain the provisioning of the NCP.…”

HiTIC-Monthly: A High Spatial Resolution (1 km×1 km) Monthly Human Thermal Index Collection over China from 2003 to 2020

“…Human thermal stress is related to temperature, topography, land cover and land use, population density, surface water, and vegetation (Wang et al, 2020;Rahman et al, 2022;Krzysztof et al, 2021). In this study, eight variables reflecting the changes and spatial distribution characteristics of temperature were 170 used to predict human thermal indices (Table 1) in addition to the meteorological variables.…”

“…The changes and impacts in human thermal stress have attracted increasing attention in recent years (Schwingshackl et al, 2021;Krzysztof et al, 2021;Li et al, 2018;Rahman et al, 2022;Ren et al, 2022;Luo and Lau, 2021). For instance, Szer et al (2022) estimated the impact of heat stress on construction 85 workers based on the universal thermal climate index (UTCI).…”

HiTIC-Monthly: a monthly high spatial resolution (1 km) human thermal index collection over China during 2003–2020

“…The changes and impacts of human thermal stress have attracted increasing attention in recent years (Schwingshackl et al, 2021;Krzysztof et al, 2021;Li et al, 2018;Rahman et al, 2022;Ren et al, 2022;Luo and Lau, 2021). For instance, Szer et al (2022) estimated the impact of heat stress on construction workers based on the Universal Thermal Climate Index (UTCI).…”