Nicknamed "the abode of silence", the Rub al-Khali desert (in French "the Empty Quarter") unfolds over Saudi Arabia, Oman, the United Arab Emirates and Yemen.
With 650,000 km2, its area equals that of France, Belgium and the Netherlands combined, its aura that of the great prohibitions for European adventurers.
"Only Bedouins can live here", commented the Briton Thesiger, one of the first Westerners to have crossed in 1946-1947 this merciless desert with red, honey or golden colors, the largest uninterrupted expanse of sand in the world.
Wilfred Thesiger (left), then 89 years old, received on February 20, 2000 by Sheikh Hamad ben Zayed al-Nahayan, Minister of Foreign Affairs of the Emirates, in Abu Dhabi.
The explorer was one of the first Westerners to cross the Empty Quarter in 1946-1947 © / WAM/AFP/Archives
It rains less than 35 mm per year on average in this furnace with cold nights, and the dune colossi can exceed 250 meters in height.
"It's a place where you don't venture alone," writes Thesiger.
"Of course there will be difficulties to stay the course, but that's what I like", comments Mathieu Baumel, co-driver of Nasser Al-Attiyah in the lead overall with their Toyota.
Land of exploits
The Dakar is not the only one to make this exceptional setting a theater of extreme challenges.
In December 2021, the Finnish runner Jukka Viljanen launched the crazy bet of swallowing 1,300 km in 25 days in this desert.
In January 2016, three intrepid walkers, their local guides and their camels completed a 50-day journey between southern Oman and Qatar via vast uninhabited areas in Saudi Arabia.
By rubbing shoulders with sandstorms, scorpions and snakes, the British explorer Mark Evans, at the head of the team, retraces the distance traveled in 1930 by his compatriot Bertram Thomas, who, despite the threat of tribes and constant search for water, had taken 57 days to complete his expedition 85 years earlier.
Their crossing was scrutinized by scientists, including Nathan Smith of the University of Northampton.
They studied the psychological processes in this hyper-arid environment and these extreme conditions, and the challenges that this poses, similar to travel in the Arctic and Antarctic, in terms of stress in particular.
"irremediable disappearance"
The Empty Quarter and its exceptional pile of sand is also a playground for scientists.
One of the treasures of dunes is to retain moisture under their surface, "which is crucial for the survival of micro-organisms present in the sand, and consequently, to allow life to exist there despite the rigors climate", explains Michel Louge, professor emeritus at the American University of Cornell.
In this context, scientists have shown that "each dune has a unique microbiome that differentiates it from adjacent dunes, while more complex organisms, such as insects or reptiles, are relatively less differentiated from one dune to another" , continues Michel Louge.
"Microbes do not have the advantage of small legs to move from one dune to another. Therefore, the destruction of a dune implies the potential disappearance of microbes in an irremediable way", indicates the scientist.
However, "all human activity is not neutral", notes Clément Narteau of the Institute of Physics of the Globe in Paris.
"If from a mechanical point of view, a trace of a vehicle in the dune is not very serious - it changes its dynamics a little but a wind can make it regain its shape -, it can be on the fauna because , in such an arid environment, the ecosystem is more fragile".
Another "big problem" according to him: the impact of vehicles on the dunes by the sea, while the Rub al-Khali goes to the Gulf in the United Arab Emirates.
German Jutta Kleinschmidt driving a Mitsubishi Pajero during a stage of the UAE Desert Challenge on November 3, 1998 in the Empty Quarter © JORGE FERRARI / AFP/Archives
"If 4x4s drove over the dunes that border the Atlantic, it would make them weaker to protect against coastal assaults," he says.
"Arid regions are among those that should inspire the most respect, notes Professor Louge, because they demonstrate how life is able to adapt to extreme atmospheric conditions, which I fear is the future of the planet if nothing is done to avoid it."
© 2023 AFP