Cape Town – With parts of KwaZulu-Natal having been turned into a winter wonderland last week, the rare occurrence of snow in Hillcrest specifically had residents debating whether more extreme weather patterns can be expected in future, with drier summers.
The intense cold front that made landfall over South Africa on Thursday also led to snow aplenty on high-lying areas in the Western Cape and the Eastern Cape.
Dr Peter Johnston, a climate scientist at the University of Cape Town, whose research focuses on the applications and impacts of climate variability and change on various user sectors, explained to IOL on Monday why the country will be experiencing more rare, extreme weather.
’’I know Pietermaritzburg and Hillcrest are not particularly close to the Drakensberg but they are close enough to have been affected by the predicted snow. The point was it was very cold air, Durban got to 7 or 8 degrees, which is very cold for them,’’ Johnston said.
’’This extreme event in Hillcrest, it could have been Hillcrest, it could have been Kloof, it could have anywhere around there. Satellite pictures showed that the Drakensberg and Lesotho got snow, so it’s just a luck of the draw whether Hillcrest got snow.
’’It was a cold snap, when a deep frontal system moved into the interior and sat behind very cold air coming in from the Antarctic, not directly but from from very cold regions. Some people issued fake forecasts saying it was going to snow in Johannesburg, but that was never from any official forecasters.
’’The melting of the Antarctic ice, which is a consequence of global warming, is releasing a lot of cold water into the sea around the Antarctic, which cools the air, and that doesn’t happen every year. It caused this cold weather, but we have been suggesting that we are going to be experiencing more of these extreme events.
Snowing in Hillcrest Kwazulu Natal. First time ever pic.twitter.com/Y9HpYoWd5j
— Keith (@brodie66051727) August 28, 2021
’’Not all of them will be very hot weather; some of them will be very cold like we have seen in North America over the last couple of years, where we have seen incursions of very cold air and very severe ice storms, but then they also have had very hot weather and the fires.
’’You can ask whether it is going to happen more often. The fact of the matter is that we are getting warmer and experiencing fewer snowfalls and fewer cold fronts in the Cape, but every now and then we get a very wet winter. This winter has been particularly cold, on average only about 1 degree colder, but that is a significant difference when you talk about statistics over very many years.’’
Commenting on the reason for these changing weather patterns, Johnston said: '’The only thing causing it that we know of, there is no natural variation other than the usual seasonal shifts, is human-induced global warming and this global warming is causing higher variability in our climate, leading to extreme events.
’’So while we are quite happy to say South Africa is warming up and the chances of frost and snow are reduced, we are never going to say they are going to disappear and, in fact, we always said and stick to this that there are going to be more extreme events, both dry and hot, and cool and wet.
’’Climate change is a long-term thing, we measure climate change over 20-year periods because your weather and variability is variable over 20 years. Statistically, we use 30 years or more to measure averages. If we look at the period 2050 to 2070, or 2040 to 2060, the whole country is predicted, with quite a high degree of certainty, to get at least 1 degree warmer.
’’Accompanied with that warming, there is a very likelihood of it being drier in general over the country than it being wetter. So if it’s more likely to be drier than wetter, we can’t definitely say there is going to be a drought in 2040 and another one in 2042, but we can say that the frequency is going to increase and the likelihood of any particular year being a dry year is going to increase.
’’All our forecast are projecting that the interior of SA, the summer rain, is going to have normal to above normal rainfall, but that does not mean that the places that have been drought-stricken are going to go back to normal and that next year or the year after there is going to be a drought.
’’The bottom line is we are a dry country and water-insecure and clearly drought doesn’t really matter if we don’t have enough water to see us through the normal years let alone the dry years. That’s really the human issue behind it and the second human issue is that with drought and increased temperatures, food security is severely threatened, with a likelihood of more crop failures.
Johnston has told friends that he has never seen so much snow on the mountains in 55 years, with a photograph doing the rounds from Fish Hoek with the Hottentots Holland Mountains in the background.
’’There has always been snow on Table Mountain, it is over 1 000 metres and anything higher than the freezing level (900 metres), when the temperature goes below zero, then the top of Table Mountain is going to get snow.
’’In Joburg, the freezing level has actually dropped to the surface and there has been snow in Joburg, I think in 1995 or 1997.
’’We really hope the Western Cape is going to continue to have snow because that ensures a regular supply of water that soaks down into the crevices and cracks of the rocks and refills the groundwater, which makes its way to dams long after winter and keeps our dam levels normal, whereas rain just washes down immediately.
’’The cold fronts that are coming past are reducing in number and are likely to reduce not because the fronts themselves are fewer, but because they miss the Western Cape. We have had a three-year period where we hardly had a frontal system that came past at all and we are expecting that in the long term.
’’But when it comes to Mediterranean regions and rainfall, because they entirely dependent on frontal systems, something that is generated so far away and influenced by so many factors, you can’ really say definitively that we are going to get that much less rain.’’
IOL