Conference Presentation
Reference
Human Exposure to Dangerous Heat in African Cities
ROHAT, Guillaume Thibaut, et al.
Abstract
Very hot and humid weather often leads to numerous health issues, ranging from heat cramps to death. Due to changing climatic conditions and to demographic growth, the number of people exposed to very hot and humid days is increasing worldwide. This is particularly the case across the African continent, where population growth is rapidly increasing and very hot and humid days are becoming more and more frequent, particularly in tropical areas. In this study, we consider more than 150 large African cities across 43 countries and project the number of people that will be exposed to dangerous heat conditions. Our projections suggest that this number will be 20 to 52 times higher at the end of the 21st century than currently.
Large cities in Western and Central Africa appear to be particularly at risk, whereas cities in Southern Africa will remain relatively unscathed. We also show that a restrained urban demographic growth could lead to a 50% reduction in the number of people exposed to dangerous heat conditions. Population and urbanization policies should be part of the wide range of urban climate adaptation options in [...]
ROHAT, Guillaume Thibaut, et al. Human Exposure to Dangerous Heat in African Cities. In:
AAG, Washington DC (USA), 6th April 2019, 2019
Available at:
http://archive-ouverte.unige.ch/unige:115901
Disclaimer: layout of this document may differ from the published version.
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Human Exposure to Dangerous Heat in African Cities
AAG – April 2019
Co-authors: Johannes Flacke, Alessandro Dosio, Hy Dao, Martin van Maarseveen
Guillaume Rohat
Case-study – 173 African cities
How climate change and demographic growth will influence future population exposure to extreme heat in urban areas of the African continent?
Scenario framework
Use of the complete RCP*SSP matrix to explore full range of plausible futures
Experiments with fixed demography: climate effect
Experiments with fixed climate: population effect
Baseline SSP1 SSP2 SSP3 SSP4 SSP5
Historical X X X X X X
RCP2.6 X X X - X -
RCP4.5 X X X X X X
RCP8.5 X - X X X X
Heat hazard and population projections
Heat Index = number of days/year when apparent temperature (Rh&T°) is > 105°F (40.6°C)
Emerging new heat hazard vs reinforcing existing heat hazard
Population projections: spatial and non-spatial approaches
SSP4 leads to the highest population growth in most cities
Scenario matrix of exposure projections
Unit: person-days/year
Along a row: influence of demographic growth
Along a column: influence of climate change
We can guess a significant
influence of demographic growth on future exposure to dangerous heat, particularly under SSP4
SSP4*RCP8.5 and SSP1*RCP2.6 lead to highest and lowest
exposure
Effects (population, climate, interaction)
Population and interaction effects dominate in most cases
Population effect very high in cities where
demographic growth is much larger than changes in HI (e.g. Niamey)
Interaction effect very high in cities with newly
occurrence of dangerous heat conditions, combined with demographic growth (e.g. Dar es Salaam)
Avoided exposure
Avoided exposure due to shifts in SSPs (SSP4 to
SSP1) is slightly greater than avoided exposure due to shifts in RCPs (RCP8.5 to RCP2.6)
Population policies must be mainstreamed in adaptation strategies
Thank you!
Guillaume.rohat@unige.ch
Rohat et al. (2019) Projections of human exposure to dangerous heat in African cities under multiple climatic and socioeconomic scenarios. Earth’s Future, In Press.
