2021 was among top 5 hottest years for world. In SA, it was milder - for now

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Acording to data collected by Berkeley Earth, South Africa's temperatures warmed by 1.6 degrees Celsius in 2020.
Acording to data collected by Berkeley Earth, South Africa's temperatures warmed by 1.6 degrees Celsius in 2020.
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  • Recent estimates from the South African Weather Service shows that 2021 was the 13th hottest year on record.
  • Globally it is expected that 2021 was among the top 5 hottest years ever, but local temperatures have been milder due to La Niña, according to a climatologist.
  • The trend of rising temperatures will negatively affect crop yields and human health, according to researchers.

Recent estimates from the South African Weather Service (SAWS) show that 2021 was approximately the 13th hottest year on record.

Overall South Africa's temperatures in 2021 were milder than in previous years, but they're still increasingly warmer - in line with global trends. Rising temperatures are associated with droughts and heatwaves, which have negative impacts on crop yields and human health, researchers have warned.

According to the data from the SAWS the warmest year for South Africa on record is 2019. "[This is] mainly due to very high temperatures in the central and western interior, because of the extreme drought that occurred there," said SAWS chief scientist for climate service, Dr Andries Kruger.

The years 2015 and 2016 were also among the hottest. 

"The summer of 2015/16 was exceptionally hot in the eastern interior, while in 2016 it was especially the western parts of the country that experienced well above-normal temperatures," Kruger explained.

Globally, data from the European Union's Copernicus Climate Change Service, shows that 2021 could be the fifth hottest on record, Bloomberg reported last week. Similarly, The Guardian reported that 2021 could be in the top five or six of hottest years, according to data compiled by climatologist Maximiliano Herrera.

Berkeley Earth - a US-based non-profit and independent environmental data science organisation - shows that in 2020 global temperatures warmed by 1.3 degrees Celsius. In South Africa, temperatures warmed by 1.6 degrees Celsius. Data on 2021 trends will be added later in the year, Berkeley Earth climate scientist Zeke Hausfather told Fin24.

Warming temperature trends observed for Johannesbu
Warming temperature trends observed for Johannesburg and surrounds. (Chart: Berkeley Earth).
Supplied Berkeley Earth

In a tweet Hausfather noted the overall warming trend, he however highlighted that 2021 was a bit cooler due to La Niña - a weather event in the Pacific Ocean.

La Niña effect

Kruger said that La Niña played a role in milder temperatures experienced in South Africa. "… La Niña is associated with an increased likelihood of rainfall in the summer rainfall region of South Africa. More often than not, milder or cooler temperatures are experienced during prolonged periods of above-normal rainfall."

Dr Christien Englebrecht, the SAWS lead scientist for long-range forecasting, similarly indicated that the milder daytime temperatures experienced over large parts of the country this summer season are driven by the presence of clouds and rain. The current La Niña conditions are expected to continue during the summer season.

There is also a greater probability of above-normal rainfall throughout January to May 2022, according to a separate note issued by the SAWS in December 2021. Data from the SAWS shows that the country received normal, to above-normal rainfall during spring and the rainfall in the Western region also provided relief from drought.

Record breaking temperatures

Apart from general warming trends, South Africa is also breaking maximum temperature records, more frequently than expected,  research by University of Pretoria PhD student Charlotte McBride showed. Her paper, Trends in probabilities of temperature records in the non-stationary climate of South Africa, was published in the International Journal of Climatology last year. McBride co-authored the paper with her supervisors, Kruger and associate professor of meteorology at the University of Pretoria, Liesl Dyson.

Using data from 25 weather stations across the country, McBride investigated record-breaking temperature events in the country. The data spanned between 1951 and 2019. It showed more records were broken than were expected over a particular time period.

"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," said McBride.

Professor Tulio de Oliveira, director of the Centre for Epidemic Response & innovation in South Africa, noted in a tweet that hot conditions are conducive for the spread of arboviruses - or those spread by insects that bite and feed on blood.

According to the United Nation's Intergovernmental Panel on Climate Change (IPCC), if global temperatures reach or exceed 1.5°C of warming, there will be increasing heat waves, longer warm seasons and shorter cold seasons.

Co-author of the IPCC report, Francois Engelbrecht - who is also a professor of climatology at the Global Change Institute at Wits University - previously noted that southern Africa is expected to become warmer and drier and will raise the risk of "day zero-type" droughts. 

McBride's research supports calls from Berkeley Earth and the IPCC to reduce carbon and greenhouse gas emissions which causes global warming. This includes making use of renewable energy resources, water saving, recycling and supporting locally-grown produce, among other things, McBride noted.

Berkeley Earth highlights that among the strategies to reduce emissions to zero includes seeking alternatives to fossil fuels. Its data shows that in South Africa, annual carbon emissions per person average 7.6 tonnes, this is the 40th highest in the world or 1.7 times the world average.

The Climate Transparency Report of 2021, compiled by the Energy Systems Research Group at the University of Cape Town, last year found that South Africa has the highest carbon intensity among G20 countries. South Africa's energy sector is still heavily reliant on coal which contributes to high levels of emissions, Fin24 reported previously.

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