Climate change, population growth and urbanisation are instrumental in increasing exposure to extreme temperatures.
Climate change, population growth and urbanisation are instrumental in increasing exposure to extreme temperatures. Researchers at the University of Geneva (UNIGE), Switzerland, – in collaboration with the University of Twente (Netherlands) and the EU Joint Research Centre in Ispra (Italy) – assessed a range of possible scenarios regarding the rate of climate change and socio-economic development in 173 African cities for the years 2030, 2060 and 2090. Their results, which are published in the journal Earth’s Future, show that a third of African city-dwellers could be affected by deadly heat waves in 2090. The projections also highlight the influence of socio-economic development on the impact of climate change.
The effects of climate change are felt specifically in countries with tropical climates, which are characterised by high humidity and very high temperatures. Furthermore, countries in these regions – especially in Africa – are experiencing heavy urbanisation and socio-economic development, leading to an explosion in the size of urban populations. A combination of these two factors is having a major impact on the living conditions of city-dwellers in Africa, especially in terms of exposure to extreme – or even lethal – temperatures. “We consider the critical threshold to be 40.6°C in apparent temperature, taking humidity into account,” says Guillaume Rohat, a researcher at UNIGE’s Institute for Environmental Sciences (ISE). In fact, high outdoor humidity levels disrupt our ability to thermoregulate, with potentially fatal consequences.
The scientists from UNIGE, the University of Twente and the EU Joint Research Centre based their research on scientific climate projections and future urban demographics (rather than on current demographic data) to calculate the risk in the years ahead – which was in itself a first. “The idea was to factor in all possible scenarios regarding climate change and urban population growth, the best and the worst, so we could find out what the future holds,” explains Guillaume. The scientists then combined five scenarios based on socio-economic projections and three climate change projection scenarios carried out by the Intergovernmental Panel on Climate Change (IPCC) for the years 2030, 2060 and 2090. “This gave us twelve different plausible combinations for each of the years. It also meant we could calculate the number of people per day exposed to apparent temperatures above 40.6°C in cities in Africa on an annual basis. The same individual can be counted several times, because he or she may be exposed to these heat waves several days a year,” continues Guillaume. Based on these twelve models, the scientists analysed the demography, urbanisation and climate in 173 cities with at least 300,000 inhabitants in 43 countries across Africa.
Read more at: Universite de Geneve
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