Heat Vulnerability Index highlights risk areas for old people in London

13 September 2016 Consultancy.uk

The reality of global warming is fast hitting cities in their pockets as resilience planning and mitigation are becoming costly priorities. A new report considers London’s vulnerability to heat, based on an analysis of the city’s environment coupled with social data about its most vulnerable people – allowing policy makers and planners to create ways of dealing with high climate pressures.

Cities around the world are turning their attention to the very real and increasingly expensive consequences of human induced climate change. While carpe diem signifies the current pressing need to sort out the issues around human induced climate change from the scientific community, politicians tasked with the development and implementation of policies appear to be childishly sitting on their hands, while businesses appear only interested in themselves.

Future Cities infographic

According to a new study from Arup, cities around the world, whose populations continue to grow on the back of urbanisation, will see an increased impact of climate events as the global climate changes. Particularly coastal cities will face burdens as sea levels rise, once in a life-time storms become more frequent and acidification takes its toll on marine life. Cities like London too will face mounting challenges, as a mixture of environmental and social factors come to bite.

The report from Arup and partners, including University College London, King’s College London, ClimateUK, HelpAge International and Satellite Applications Catapult, titled ‘Seasonal health and resilience for ageing urban populations and environments’, explores the effect of two major trends on the health of people within cities: the changing climate, which increases the frequency and severity of events, and changing demographics, relating to more old and vulnerable people in less space.

The changes in climate around London are projected to see a third of summer days exceed the heatwave threshold by 2050, while by 2080, the chances are that heatwaves, similar to the one in 2003, may occur every second year. The UK population is also set to age, with the population of people over the age of 65 in London set to increase by 46% by 2030 while those aged over 90 is set to double in the same period – globally, by 2050, 22% of the world will be aged over 65. Heatwaves can be severely detrimental to the health of vulnerable, particularly old, people. The 2003 ten day heatwave killed 2,000 people across the UK, while the three day heatwave in 2009 saw almost 300 people succumb to the heat.

Land cover and heat map

London heat and vulnerability

As part of the study, the consultancy firm and its partners developed comprehensive maps of various conditions in the studied cities, London, New York and Shanghai. These maps provide an overlay of areas which are particularly affected by conditions – such as heat and flooding.

For London the maps provide insight into the areas that see the most and the least warming during heatwave events by mapping temperature against the features of a city, including green spaces, water bodies and built-up areas as well as the areas with the highest heat profiles – the city is 69% built up area. According to the study, areas around green spaces and near water bodies tend to be the coolest, while large areas of built environment tend to be the hottest (also known as the Urban Heat Island effect). 

Vulernability factors

The consultancy firm also considered demographic conditions for the cities. For London the firm used census information to map various factors related to vulnerability of people within various areas of the city. Factor 1 include population density, rented housing and persons speaking no English; factor 2 involved mapping out areas in which people with bad and very bad health tend to reside; and factor 3 considers housing that lacks central heating. Factor 1 was given the most weighting, followed by factor 2 and 3.

Heat Vulnerability Index

Heat Vulnerability Index

Combining the environmental and city feature data with social data related to vulnerable people, results in a ‘Heat Vulnerability Index’ (HVI). The HVI gives insight into which areas of the city will have the highest levels of vulnerable people give a heat related event in the city. According to the analysis, the most areas of highest vulnerability are London Boroughs of Hackney, Islington and Tower Hamlets while the lowest values are found in Bromley, Richmond upon Thames and Sutton. Central and North East London tends to be the area with the most vulnerable people to heat events. Similar maps can be created for flooding and other events to aid development of resilience measures.

Polly Turton, Environmental Consultant at Arup, says, “The combination of climate change, rapid urbanisation and ageing populations is increasing the impact of extreme weather events, such as heat waves, experienced by global cities like London. We all – planners, urban designers, engineers, property developers and politicians – have an opportunity to help vulnerable members of our communities cope with increasing heat waves. Measures don’t need to be expensive – but we need to take action now. For example, something as simple as planting more trees now will provide vital shade for communities and significant cooling benefits in decades to come.”


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