If it feels hotter, that’s because it is.
New research by a PhD student at the University of Pretoria’s department of geography, geoinformatics and meteorology has found that South Africa is breaking more maximum temperature records than expected, with its climate “becoming more extreme”.
As warming accelerates in the country, high-temperature records are likely to be broken at a higher-than-expected rate, according to Charlotte McBride, the manager of climate data at the South African Weather Service (Saws).
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She investigated record-breaking temperature events over South Africa by using weather station data from 25 stations across the country, drawing from daily temperature data for 1951 to 2019. Her study, published in the International Journal of Climatology, is the first local research to focus on such events.
“The [weather service] publishes this type of information on its webpage,” she said. “I was curious about whether there was a change in the occurrence of these records, especially in light of other research coming out with regards to climate change. Some members of the public were also asking about this and we were not able to give a comprehensive answer.”
Not only is South Africa warming, but records are being broken more frequently than one would expect. “This implies that our climate is becoming more extreme. My research shows that most stations broke higher daily maximum records than what is expected in a climate that isn’t under the influence of climate change,” McBride said.
What surprised her the most were the disparities in the records. “Some stations are recording many more high Tmax [daily maximum temperatures] and high Tmin records [daily minimum temperatures] than others,” she said.
Pretoria was expected to break an annual average of nine maximum temperature records a year over the past 10 years of the study when taking into account the warming taking place at that station. However, on average, it broke 15 records a year.
The study also found that the increased above-expected number of high daily Tmin temperatures occurred over highly populated areas such as Johannesburg and Pretoria.
“These 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, especially those without access to air conditioning, at risk,” McBride wrote in her paper.
“This is further exacerbated by the fact that many in South Africa live in informally constructed homes which result in highly fluctuating temperatures, with indoor temperatures being between 4°C to 5°C warmer than outdoor temperatures.”
Research in major cities in South Africa has found that a 1°C increase in daily ambient apparent temperature resulted in a 0.9% increase in the mortality rate, according to the paper.
Coastal stations are not showing as high ratios in favour of the high Tmax as interior stations; the research suggests this could be because of the role the ocean plays in the regulation of temperature.
The researchers said the higher than expected numbers of high Tmax and high Tmin records in the latter part of the analysis period “were mainly due to the variability in the warming trend with acceleration in the last decade”.
The findings, said McBride, correspond with the recent sixth assessment report from the Intergovernmental Panel on Climate Change, 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 21st century.
The trend towards increases in temperature, together with other climate-change-related threats pose challenges for how South Africa is able to respond in terms of water, food security, and human and ecosystem health and development, McBride said.
Higher temperatures can affect crop yields and contribute to the spread of pests and pathogens; they can also cause heat-related illnesses. Farmers may need to review the types of crops or crop varieties they plant to ensure that they are more suited to a warmer climate, she said.
“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,” McBride said.
“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.”
McBride is now examining record-breaking events using rainfall data. “This will hopefully then be able to add to our knowledge about how these records are being broken and whether different stations are showing different patterns in the breaking of these records.”
The general public experiences climate change mostly through the occurrence of extreme events and are able to understand records, she said. “Record-breaking events are considered to be extreme events,” McBride said. “If we, as scientists, can add to the conversation around climate change from a point where the public is able to understand, I think this is very important.”