Blowout
8 March 2025
A nasty wind rips across Cornell’s Kop one afternoon in the spring of 2024, driving emeritus professor Timm Hoffman and his team to abandon the hilly study site a few clicks west of the |Ai-|Ais Richtersveld Transfrontier Park that straddles the South Africa-Namibia border along the Orange River.
The team only has three days to complete their work, and this is likely the retired professor’s last research visit to a family of giant quiver trees, the critically endangered Aloidendron pillansii, that the former head of the University of Cape Town’s (UCT’s) Plant Conservation Unit has monitored for 20 years and speaks of tenderly.
The volley is brief but merciless, coming from the south-west, flinging confounding curtains of sand in the researchers’ faces and tugging maddeningly at their gear as they flee for the shelter of the plains below.
Hoffmann’s visit to Cornell’s Kop becomes yet another data point in an ever more complex picture of what’s driving this part of the once succulent-resplendent Karoo to tip towards dust bowl conditions.
Whodunnit? Climate modelling suggests that wind speeds will pick up in these parts as land surface temperatures climb at a rate faster than sea temperatures, creating a bigger temperature gradient between the two and stirring the air to move faster. Is this already happening, and driving a wildfire of spreading desert conditions in the Richtersveld?
The desert wind is notorious for whipping up furious sandstorms that can ruin the paintwork on vehicle in an hour or two. Worse still, it can lay waste to plants, sandblasting them lethally, and clogging up their stomata so they can’t breathe. The more vegetation that gets killed in this way, the more ground is left exposed to the wind, allowing the desert to spread like a wildfire. Many of the locals living in places like Kuboes, the Nama settlement on the edge of the Annisvlakte, and Eksteenfontein, say the winds and sandstorms seem to be getting worse.
Henley Strauss is a proud member of the “Bosluis Basters” in Eksteenfontein, a community whose mix race made them fall foul of the apartheid governments ideology of racial purity. Just over 100 families were evicted from a farm “Bo-Sluis” (“above the sluice”) outside Pofadder in 1948 and relocated to the Richtersveld. Shepherding runs in their blood. They are deeply attuned to environmental conditions and weather patterns, which is why Strauss is working closely with researchers to understand what’s driving the spreading desert conditions.
One researcher first noted something was amiss in 2020 when she was poring over satellite images taken above the Northern Cape. Dr Johanna von Holdt, an environmental scientist from the UCT Department of Environmental & Geographical Science who specialises in air quality, noted a dramatic increase in sand plumes. They look like smoke rising from a chimney stack, although the plumes lie on the ground, starting as if from a single ignition point, fanning out over the landscape and heading out to sea. (Source: Nasa; and Dr Johanna von Holdt.)
In 2022, Von Holdt lead a team of arid systems ecologists and others on a trip to the Richtersveld. Not only did they confirm what the high-altitude photographs are saying about the intensity of the offshore sand plumes. They also found evidence that onshore winds are sending sand into the interior, something that’s particularly noticeable where they cause dune-like eddies to collect on the leeward side of hills and rocks.
This team has been sifting through the data to make sense of what’s driving the advancing dust bowl conditions. Temperatures are definitely up, and the drought seems to have killed of 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.
It doesn’t look as though the data is 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 Dr 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 that 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 those that have evolved sophisticated ways to survive this kind of pummelling.
What struck Hoffmann most during his recent visit to Cornell’s Kop are the eddies of dune sand washing up against rocks and in deep leeward drifts. Today, small dunes lap up against the quiver trees’ boles and catch 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 m.
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.
The giant quiver tree (Aloidendron pillansii) is the most charismatic of the three tree aloe species that have drawn photographic trophy hunters for years.
The common quiver tree (Aloidendron dichotomum) grows widely across Namaqualand and the Nama Desert.
The endangered maiden’s quiver tree (Aloidendron ramosissimum).
Like many of the desert-adapted plants in the Richtersveld, these three tree aloe species are showing the strain of a hotter, drier world.