The development of a heat wave vulnerability index for London, United Kingdom

The health impacts of heat waves are an emerging environmental health concern. This is especially so for large cities where there is a concentration of people and because of the urban heat island effect. Temperatures within cities can reach stressful levels during extreme temperature events. To better manage heat related health risks, information is required on the intra-urban variability of vulnerability to heat wave events. Accordingly a heat vulnerability index (HVI) is developed and presented for Greater London in the United Kingdom. The approach to HVI development adopted is an inductive one whereby nine proxy measures of heat risk are extracted from the 2001 London census for 4765 census districts and subject to principal components analysis. Scores for the emergent principal components are weighted according to the variance they explain and summed to form the HVI. Although mapping of the HVI shows what appears to be a heterogeneous heat “risk-scape” statistical testing reveals significant spatial clustering of areas of high heat vulnerability in central and east London which also co-occur with areas of potentially high heat exposure. Drivers of the spatial pattern of heat vulnerability are discussed as are the implications of study results for heat risk management in large cities.