Heatwaves new threat to urban populations

Sunday March 20 2022
Maralal Town

Zebras that wandered into Maralal Town in search of water. PHOTO | FILE


Global warming and heatwaves could make heavily populated urban areas increasingly hard to live in, new research shows.

The World Meteorological Organisation declared 2019 one of the warmest years globally since 1850. Across Africa, most heatwave hotspots were linked to urban areas owing to the significant economic activities carried in them and the populations residing in them, a Chinese team of scientists said.

The scientists say the strongest heatwaves were observed between November and March, with 60 percent of the total land area in Africa affected.

In the Southern Hemisphere there were 24 days of heatwave events where temperatures increased by three degrees Celsius and in the north, for eight days temperatures increased by 1.8 degrees Celsius.

The researchers highlighted the increasing risks posed by heat events in highly populated urban areas, and warned that these hotspots could become inhabitable by the end of the century.

“Heatwave hotspot areas were clearly linked to urban populations, particularly in western-coastal, northeastern, southern and equatorial Africa, where the vast majority of the human population is located,” said the scientists from the Institute of Atmospheric Physics, Chinese Academy of Sciences in a publication on March 9.


Increased exposure

They said the proportion of urban populations exposed to extreme heatwaves in the Northern Hemisphere rose from four percent (or approximately five million people) between 1981 and 2010 to 36 percent (43 million people) in 2019. In the Southern Hemisphere 53 million people (57 percent) were exposed in 2019, up from 17 million people (15 percent) between 1981 and 2020.

Significant increases in the frequency and duration of heatwave events have been noted over Africa due to climate change, and scientists are warning that considering the rapid population growth and urbanisation, heatwaves may place further pressure on existing water and energy shortages.

“These findings are significant for human health, energy consumption and water security in developing and vulnerable regions such as Africa that are experiencing population growth but have low adaptive capacity,” explains study co-author, Prof Gensuo Jia. “We therefore advocate for sustainable urban planning with innovative solutions to help minimise the impact of heatwave exposure.”

The results also show that there was a major shift in the spatial distribution of heatwave hotspots from the equatorial region in the baseline period (1981–2010) to large areas up to the temperate climate zones (above 30°N and 30°S) in 2019, affecting more urban clusters.