The Urban Heat Island: Implications for Health in a Changing Environment

Abstract

Climate change, increasing urbanisation and an ageing population in much of the world, is likely to increase the risks to health from the UHI, particularly from heat exposure. Studies have shown increased health risks in urban populations compared with rural or suburban populations in hot weather and a disproportionate impact on more vulnerable social groups. Estimations of the impacts of various mitigation techniques suggest that a range of measures could reduce health impacts from heat and bring other benefits to health and wellbeing. The impact of the UHI on heat-related health is significant, although often overlooked, particularly when considering future impacts associated with climate change. Multiple factors should be considered when designing mitigation measures in urban environments in order to maximise health benefits and avoid unintended negative effects.

The impact of climate change and urban growth on urban climate and heat stress in a subtropical city

“…Not only do the number of hot nights increase, but extreme events with consecutive hot nights last longer with climate change, and in the urban growth scenario. Consecutive hot nights negatively impact on human health and are linked to increased mortality (Heaviside et al ., ). Days with minimum temperature over 24 °C, which matches the definition of hot nights used here, have been linked to increases in daily mortality for those over 65 of 19–21% (Nicholls et al ., ).…”

“…During heat waves, the death toll can rise to the thousands, as seen in Europe in 2003 and 2010 (Robine et al ., ; Barriopedro et al ., ), France in 2006 (Fouillet et al ., ) and Asia in 2015 (World Meteorological Organization, ). Urban residents are particularly vulnerable to heat stress due to the “urban heat island” (UHI), whereby cities are warmer than the surrounding countryside, mainly at night (Medina‐Ramón and Schwartz, ; Heaviside et al ., ). During heatwaves, urban residents are exposed to greater risk of heat stress and higher mortality than rural residents due to the UHI (Clarke, ; Hayhoe et al ., ).…”

Impact of Air Temperature on London Ambulance Call-Out Incidents and Response Times

“…Recent improvements in estimating air temperature from satellite data are available [29,30]. The urban heat island in London and other cities compounds the health impact of heatwaves for ambulance and other health services [31,32].…”

The Challenge of Urban Heat Exposure under Climate Change: An Analysis of Cities in the Sustainable Healthy Urban Environments (SHUE) Database

“…Moreover, the analyses did not attempt to incorporate the urban heat island (UHI) effect-the name given to the occurrence of higher outdoor temperatures in metropolitan areas compared with those of the surrounding countryside caused by the thermal properties (heat absorption, capacity, conductance, and albedo) of the surfaces and materials found in urban landscapes, the reduced evapotranspiration from reduced natural vegetation, and the waste heat production from anthropogenic activities [28][29][30]. The UHI effect may add to the more general effect of increasing temperatures, especially in larger cities, though the implications for personal exposure and health are more complex [31,32] and surface temperature effects may in part be offset by overshadowing by high rise buildings in urban centres [33]. A further limitation was the relatively coarse resolution of the GCMs, resulting in an inability to distinguish some cities from neighbouring cities and potential biases for coastal cities.…”