Chronic heat stress in tropical urban informal settlements

Emma E Ramsay,Genie M Fleming,Peter A Faber,S Fiona Barker,Rohan Sweeney,Ruzka R Taruc,Steven L Chown,Grant A Duffy

doi:10.1016/j.isci.2021.103248

Abstract

SummaryThe health and economic impacts of extreme heat on humans are especially pronounced in populations without the means to adapt. We deployed a sensor network across 12 informal settlements in Makassar, Indonesia to measure the thermal environment that people experience inside and outside their homes. We calculated two metrics to assess the magnitude and frequency of heat stress conditions, wet bulb temperature and wet bulb globe temperature, and compared our in situ data to that collected by weather stations. We found that informal settlement residents experience chronic heat stress conditions, which are underestimated by weather stations. Wet bulb temperatures approached the uppermost limits of human survivability, and wet bulb globe temperatures regularly exceeded recommended physical activity thresholds, both in houses and outdoors. Under a warming climate, a growing number of people living informally will face potentially severe impacts from heat stress that have likely been previously overlooked or underestimated.

Highlights

Extreme heat stress, arising from combinations of high temperature and high humidity, has adverse health, wellbeing and economic impacts on all humans
We calculated two metrics to assess the magnitude and frequency of heat stress conditions, wet bulb temperature and wet bulb globe temperature, and compared our in situ data to that collected by weather stations
We found that informal settlement residents experience chronic heat stress conditions, which are underestimated by weather stations

Summary

Introduction

Extreme heat stress, arising from combinations of high temperature and high humidity, has adverse health, wellbeing and economic impacts on all humans. Heat stress leads to reduced productivity and work capacity, which can cause personal financial hardship and have large-scale economic consequences (Lucas et al, 2014; Orlov et al, 2020). Under a moderate greenhouse gas emissions scenario (Representative Concentration Pathway [RCP] 4.5), more than 50% of the world’s population could be exposed to potentially deadly combinations of temperature and humidity by 2100 (Mora et al, 2017), alongside losses to global Gross Domestic Product of between 0.5% and 2.4% (low and high emissions scenarios, RCPs 2.6 and 8.5, respectively) as a result of heat-induced reductions in work capacity (Orlov et al, 2020). Given that global greenhouse gas emissions are currently tracking RCP 8.5, the highest emissions scenario used by the IPCC (Schwalm et al, 2020), heat stress is likely to have far-reaching and ongoing impacts

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