SA is breaking more high-temperature records than expected

Posted on September 20, 2021

A study by a PhD student at the University of Pretoria’s (UP) Department of Geography, Geoinformatics and Meteorology reveals that South Africa is experiencing more maximum temperature records than expected and that this trend seems to be accelerating.

Charlotte McBride of the South African Weather Service had her paper ‘Trends in probabilities of temperature records in the non-stationary climate of South Africa’, published in the prestigious International Journal of Climatology. The paper was co-authored by her supervisor, Andries Kruger of the South African Weather Service, and co-supervisor, Professor Liesl Dyson, Associate Professor of Meteorology at UP.

Her research supports the sixth assessment report from the Intergovernmental Panel on Climate Change (IPCC), published recently, which indicates that the climate outlook for Africa looks bleak in terms of the increasingly high probability of extreme maximum temperatures and heatwaves projected to occur in the 21 st century.

“I investigated record-breaking temperature events over South Africa by using weather station data from 25 stations across the country,” McBride explains. “Daily temperature data for the period 1951 to 2019 was used.” The analyses showed that significantly more records were broken than one would expect to occur over a particular time period. Also, in the most recent decade, it was evident that the measured number of maximum temperature records became progressively greater compared to the expected number.

“We thus have evidence that South Africa is not only warming, but that records are being broken more frequently than one would expect,” McBride says. “This implies that our climate is becoming more extreme. My research shows that most stations broke more highest daily maximum records than what is expected in a climate that isn’t under the influence of climate change.”

Even when this influence was taken into account, there were certain stations that still broke many more high-temperature records. “For example, Pretoria was expected to break an annual average of nine maximum temperature records per year over the past 10 years of the study when taking into account the warming taking place at that station,” McBride explains. “However, it broke on average 15 records per year. While future warming is dependent on the amount of future greenhouse-gas emissions, we have already committed our atmosphere to substantial warming in the near to medium term. Therefore, it is necessary that climate-sensitive sectors of society prepare themselves for an ever-increasing occurrence of unprecedented record high temperatures, more frequently than one would usually expect.”

She adds that warming is accelerating in South Africa, which means that high-temperature records are likely to be broken at a higher-than-expected rate. “This is of concern as higher temperatures can affect crop yields and contribute to the spread of pests and pathogens. From a human health point of view, high temperatures can cause heat-related illnesses, which put certain sectors of the population such as the elderly, very young and people with certain pre-existing medical conditions at risk.”

This research is in support of other research which is indicating that South Africa will become hotter in the future. “There is a real need to address climate change and for governments and the public to play their part in reducing their carbon footprint,” McBride cautions. “This will include making use of renewable energy sources, saving water, recycling, eating less meat, supporting locally grown produce and supporting tree planting initiatives. For those wanting to reduce their carbon footprint, there are many websites that assist all spheres of society in doing their bit.”

McBride’s research recommends that policymakers, government departments, non- profit organisations, disaster managers, farmers and developers of infrastructure need to understand the consequences and risks of the increased frequency of record-breaking temperature events so that their response strategies are more meaningful. “Farmers might need to review the types of crops or crop varieties they plant to ensure that they are more suited to a warmer climate. Town planners and the construction industry will need to take the warming into account when they plan and construct infrastructure. Health services need to be in a position to respond to increased cases of heat-related illnesses.”

This also means that investment and funding need to be more focused on creating adaptive capacity rather than just responding to disasters, she adds. “More thought is needed around how to prepare for climate extremes such as the breaking of high-temperature records rather than waiting for them to occur, then trying to address the consequences.”

Graph: Spatial distribution of the annual average number of observed maximum temperature records for the period 2010 to 2019.

Graph: Spatial distribution of the annual average number of observed maximum temperature records for the period 2010 to 2019.

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