By modifying a well-known climate model and applying it to the fictional world of Arrakis, a group of scientists has shown that Frank Herbert’s depiction of a desert planet in the book series Dune was surprisingly apt, though with some surprising differences.
Arrakis — Dune — Desert Planet.
These words, like a mantra, roll through Paul Atreides’s thoughts in the opening chapter of Frank Herbert’s 1965 classic, Dune. Our hero had a right to be worried, for his new digs would be nothing like Caladan, the water-rich homeworld he was to leave behind. Arrakis, as Paul would soon experience first-hand, lacks surface water and it never rains. The planet’s surface is covered nearly entirely by dune-filled deserts, which are depicted gorgeously in the new Dune film directed by Denis Villeneuve. This dry monotony is occasionally disrupted by mountain ranges, rocky outcrops, and the odd sandworm. And of course, there’s the intense heat.
Arrakis presents a fantastic setting for a sprawling sci-fi adventure, and Herbert’s depiction of a desert planet was not too far off the mark, as a group of scientists recently demonstrated. The team, having an expertise in climate modelling, wanted to know how a planet like Arrakis might actually function and whether humans could really live there, so they ran a simulation to find out. The resulting model, for the most part, met expectations, as the researchers write in The Conversation. True to Herbert’s vision, “Arrakis itself would indeed be habitable, albeit inhospitable,” the scientists wrote.
In an email, Alex Farnsworth, a meteorologist at the University of Bristol and a contributor to the project, said he was most surprised by how accurate Herbert was in “envisioning a desert world without having a physics background or a supercomputer to run any sort of calculations on,” adding that Herbert “must have done a huge amount of research into the various Earth system components to understand how such a world could work.”
Farnsworth, along with Michael Farnsworth from the University of Sheffield and Sebastian Steinig from the University of Bristol, sought to emulate Arrakis to the greatest extent possible, despite its fictional nature. To that end, they referenced descriptions of Arrakis from the Dune series, and also the Dune Encyclopaedia, finding, for example, that the planet is in a circular orbit like Earth.
The researchers then modified a well-known climate model to simulate their version of Arrakis, which they did by taking various factors into account, such as the planet’s topology and expected amount of stellar exposure (the team used a modern solar constant because “Herbert based much of what he knew on planet Earth,” said Farnsworth). They also presumed an atmospheric composition of 350 parts per million carbon dioxide, instead of Earth’s 417 parts per million, and they cranked up the amount of ozone, which is 65 times more efficient than carbon dioxide at warming the atmosphere across a two-decade period, according to the scientists.
As for the oxygen on Arrakis, that had to stay within the realm of science fiction. Without vegetation, the oxygen on Dune is provided by the gigantic sandworms, as Herbert stated in his book.
With the parameters set, the researchers pressed go on the simulation and waited three weeks for the computer to run its calculations. Looking at the results, the researchers were able to spot some very Arrakis-like characteristics, but with some key differences.
Extreme Heat and Frigid Cold
In Dune, the polar regions of Arrakis are described as being more hospitable than other areas, but the simulations told a different story. According to the model of Arrakis, tropical areas reach around 113 degrees Fahrenheit (45 degrees Celsius) during the warmest months and no lower than 59 degrees F (15 degrees C) during the coldest months (which is not too far removed from conditions on Earth). But the most extreme temperatures were seen at the mid-latitudes and polar regions, where summer temperatures were as hot as 158 degrees F (70 degrees C) on the sand and the winters got really, really cold, featuring temperatures as low as -40 degrees C/F in the mid-latitudes and -103 degrees F (-75 degrees C) at the poles.
“This is counter intuitive as the equatorial region receives more energy from the Sun,” wrote the researchers. “However, in the model the polar regions of Arrakis have significantly more atmospheric moisture and high cloud cover which acts to warm the climate since water vapour is a greenhouse gas.”
Does It Rain?
It doesn’t rain on Herbert’s Arrakis, but in the model, there were some small amounts of rain at the higher latitudes during summer and autumn, on mountains and plateaus. The book also describes polar ice caps — a feature that’s absent on the simulated Arrakis; this is on account of the summer temperatures being so high at the poles and with no winter precipitation to replenish the caps.
“I was also surprised that these large ‘coriolis’ storms that are said to circumnavigate the planet could in some sense be a reality also,” said Farnsworth. “Although not as powerful as the books or film depict.”
Where Could People Live?
True to Herbert’s vision of Arrakis, the simulated planet is hot, but not so hot that it cannot sustain humans. Tropical regions appear to be the most habitable, as they don’t breach the dangerous wet-bulb temperature limit. A 2019 article by climatologist Tom Matthews from Loughborough University, also published in The Conversation, explains:
When the air temperature exceeds 35°C [95°F], the body relies on the evaporation of water — mainly through sweating — to keep core temperature at a safe level. This system works until the “wetbulb” temperature reaches 35°C. The wetbulb temperature includes the cooling effect of water evaporating from the thermometer, and so is normally much lower than the normal (“drybulb”) temperature reported in weather forecasts.
Once this wetbulb temperature threshold is crossed, the air is so full of water vapour that sweat no longer evaporates. Without the means to dissipate heat, our core temperature rises, irrespective of how much water we drink, how much shade we seek, or how much rest we take. Without respite, death follows — soonest for the very young, elderly or those with pre-existing medical conditions.
As the simulation points out, an equatorial existence could work, but woe betide the unprepared explorer to who dares to travel to the mid-latitudes without a moisture-reclaiming stillsuit. There, in the lowlands, temperatures often exceed 50 to 60 degrees C, which is “deadly for humans,” according to the authors. Again, this is where the models stray from the book, as the mid-latitudes are where most of the people live on Arrakis (including the cities Arrakeen and Carthag).
This exercise was done during the researchers’ spare time and mostly for fun, but as Farnsworth pointed out, there is a serious side to all of this, as these simulations test our understanding of the physics of climate. Had a very different world been produced, it might have meant that our understanding is limited to Earth-like worlds, he said. Scientists can also use simulations to “understand climate models, not only for looking at past, present and future climate, but also the potential climate of worlds outside of our solar system,” Farnsworth explained.
At the same time, this exercise is also communicating a very important message having to do with human-induced climate change. “As Frank Herbert was a keen ecologist, I think the message would be: protect what you have, for climate such as on Arrakis is not something we would ever want to experience,” said Farnsworth.