- Botany professor emeritus Timm Hoffman and his colleagues are seeing eddies of dune sand piling up around quiver trees at study sites in northwestern South Africa.
- Hoffman has been studying the iconic trees for 20 years — the sand, which in places has formed drifts up to 2 meters (6.6 feet) deep, is new.
- Five years ago, environmental scientists noted an increase in wind-blown sand plumes in the arid areas on both sides of the South Africa border for reasons that are not entirely clear.
- This spreading sand is killing off the succulent vegetation adapted to this climate, threatening this austerely beautiful region’s biodiversity and the livelihoods of shepherds and farmers who call it home.
A nasty wind rips across Cornell’s Kop one afternoon in October 2024, driving professor emeritus Timm Hoffman and his team to abandon the hilly study site a few clicks west of |Ai-|Ais Richtersveld Transfrontier Park.
The team has only three days to complete its work here on the South Africa-Namibia border, and this is likely Hoffman’s last research visit to a family of critically endangered giant quiver trees (Aloidendron pillansii), which the botanist has monitored for 20 years.
The giant quiver tree is the most charismatic of three tree aloe species that draw photographic trophy hunters to the arid landscape spread across 1,400 kilometers (870 miles) between Namibia’s Brandberg Mountain in the north and the town of Nieuwoudtville in South Africa.
The volley of sand on that October afternoon is brief but merciless, coming from the southwest, flinging curtains of sand in the researchers’ faces and tugging maddeningly at their gear as they flee for the shelter of the plains below.
Hoffman’s visit to Cornell’s Kop gathered yet more data painting a complex picture of what’s tipping this part of the once succulent-resplendent Karoo into dust bowl conditions.
What struck Hoffman most during his recent visit to Cornell’s Kop were eddies of dune sand washed up against rocks and in deep leeward drifts. Small dunes lap up against the quiver trees’ boles and settle in rippled swells against rocky outcrops, reminiscent of the orange-hued dunes of the Kalahari.
Some of the drifts are only ankle-deep; others have piled up as much as 2 meters (6.6 feet). This dusting of sand on Cornell’s Kop wasn’t here in 2013 and isn’t in historic photographs taken as far back as the early 1940s.
Whodunnit? Climate modeling suggests wind speeds will pick up in these parts as land surface temperatures rise faster than sea temperatures, creating a bigger temperature gradient between the two and stirring the air to move faster.
Is this already happening, driving a wildfire of spreading desert conditions in the Richtersveld?
The desert wind is notorious for whipping up furious sandstorms that can wreck a vehicle’s bodywork in an hour or two. More seriously, this wind can lay waste to plants, lethally clogging up their stomata so they can’t breathe.
The more vegetation that is sandblasted this way, the more ground is left exposed to the wind, allowing the desert to spread like a wildfire over areas once-resplendent with succulents. Peter Carrick, another arid systems ecologist, helped with Hoffman’s survey.
Henley Strauss is a proud member of the “Bosluis Basters” in Eksteenfontein, one of many mixed-race communities whose existence drew the ire of the apartheid government. In 1948, just over 100 families were evicted from the “Bo-Sluis” farm and relocated to the Richtersveld, 200 km (124 mi) west.
Shepherding runs in their blood and they are deeply attuned to environmental conditions and weather patterns.
Environmental scientist Johanna von Holdt first noted a dramatic increase in sand plumes while poring over satellite images of the Northern Cape in 2020. (Source: Nasa; and Dr Johanna von Holdt.)
In 2022, Von Holdt, a professor at UCT’s Environmental & Geographic Science Department, and others traveled to the Richtersveld to confirm that onshore winds are sending sand into the interior, causing dune-like eddies to collect on the leeward side of hills and rocks.
This team has been sifting through the data to work out what’s driving the advancing dust bowl conditions. Temperatures are definitely up, says Von Holdt, and the drought seems to have killed off a lot of plant cover, leaving the ground bare and accelerating desertification pressures that have been simmering over decades and linked with diamond mining and heavy grazing.
Farmers like Strauss and many other locals living in places Eksteenfontein and Kuboes, a Nama settlement on the edge of the Annisvlakte, say the winds and sandstorms seem to be getting worse.
It doesn’t look as though the data are showing a change in wind activity, though. “We see a big increase in dust events, which we cannot seem to link with any changes in the wind conditions, even though more extensive analyses could be done here,” says Heleen Vos from the Department of Earth Sciences at Stellenbosch University, who is leading some of the number crunching for this study.
It’s likely the increase in sand being transported by the wind might make those living in the face of the sandstorms more aware of the wind and give the impression of an increase. It’s this sandblasting that’s proving so lethal, even to those that have evolved sophisticated ways to survive this kind of pummeling.
Strauss and others from the community are working with researchers to better understand what’s driving the spreading desert conditions. They’ve set up air samplers to monitor conditions and are hoping to put anti-erosion measures and wind breaks in place in heavily sanded areas.
Ultimately, the Richtersveld decides how you will farm, Strauss says. If you “farm for the eye” – if you try to impress your neighbors with a big herd – a drought will cut you down to size.
Banner image: Sheep near the Richtersveld, South Africa. Image by Leonie Joubert for Mongabay.
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