Including the urban heat island in spatial heat health risk assessment strategies: a case study for Birmingham, UK

Abstract

Background: Heatwaves present a significant health risk and the hazard is likely to escalate with the increased future temperatures presently predicted by climate change models. The impact of heatwaves is often felt strongest in towns and cities where populations are concentrated and where the climate is often unintentionally modified to produce an urban heat island effect; where urban areas can be significantly warmer than surrounding rural areas. The purpose of this interdisciplinary study is to integrate remotely sensed urban heat island data alongside commercial social segmentation data via a spatial risk assessment methodology in order to highlight potential heat health risk areas and build the foundations for a climate change risk assessment. This paper uses the city of Birmingham, UK as a case study area.

Results: When looking at vulnerable sections of the population, the analysis identifies a concentration of "very high" risk areas within the city centre, and a number of pockets of "high risk" areas scattered throughout the conurbation. Further analysis looks at household level data which yields a complicated picture with a considerable range of vulnerabilities at a neighbourhood scale.

Conclusions: The results illustrate that a concentration of "very high" risk people live within the urban heat island, and this should be taken into account by urban planners and city centre environmental managers when considering climate change adaptation strategies or heatwave alert schemes. The methodology has been designed to be transparent and to make use of powerful and readily available datasets so that it can be easily replicated in other urban areas.

Figure 1

Crichton's risk triangle (from [73] and [75]).

Figure 2

Simplified flowchart of GIS spatial risk assessment methodology (adapted and developed from [73]).

Figure 3

Detailed flowchart of spatial risk assessment methodology. All are at LSOA level except the Exposure Layer which is HH points.

Figure 4

Birmingham UHI under heatwave conditions at LSOA level. 18^th July 2006 from MODIS remotely sensed data. Shown with contour lines for validation.

Figure 5

Four "exposed and vulnerable" layers at LSOA level. Named areas are detailed in text.

Figure 6

Combined (equal weighting) "exposed and vulnerable" layer at LSOA level.

Figure 7

Final risk layer at LSOA level.

Figure 8

Mosaic type within "very high" risk LSOA. Filterered to only include HH counts > 1000.

Figure 9

Mosaic type 64 and 47 spatial distribution within "very high" risk city centre area.