Arrakis, the planet on which the novel and film Dune is set is a pretty unpleasant place, at least if you are a human and not a giant worm. It's a desert largely devoid of water, but could humans actually survive there? Indeed, could such a world even exist? A team of climate scientists decided the question was worth exploring.
Dr Alex Farnsworth studies historical climates at the University of Bristol with a fondness for science fiction and fantasy. This led him to model the climates of fictitious worlds such as the one in which Game of Thrones is set, although in that case he modestly credited Samwell Tarley with the authorship. Presumably, there needs to be some compensation for suffering all that cold.
The climate of Westeros, with seasons of unpredictable length, could never be modeled with much precision, but Arrakis is a different matter. The spice that makes spaceflight possible may be a magical element, but the concept of a barely habitable desert world is perfectly realistic. Indeed, having been hailed as responsible for launching the field of ecological science fiction, Dune's central world is the perfect one to explore in this way.
Farnsworth and colleagues have posted the product of their work to their website where anyone can watch air flows over its mountains, The Great Flat and poles, and the occasional clouds and tinker with the settings.
“We decided to keep the same fundamental physical laws that govern weather and climate here on Earth,” the model-makers write in The Conversation. “If our model presented something completely strange and exotic, this could suggest those laws were different on Arrakis, or Frank Herbert’s fantastical vision of Arrakis was just that, fantasy.”
Herbert indicated Arrakis has a near-circular orbit, rather than seasons complicated by large variations in distances from its star. Combined with many descriptions of its topography and atmosphere through Herberts' 6 books and his son's sequels, this provided the authors with information to feed into the model.
Remarkably, the team managed to score three weeks of time on a major supercomputer to make the model run.
Not everything in Herbert's description turns out to be realistic. Intuitively, his portrayal of a world with a scorching equator and refuges from the heat at the poles makes sense, but the model showed this isn't how things would work. Without the moderating effect of oceans, Arrakis' polar regions would be intolerable, swinging from temperatures of 70º C (158º F) in summer to -75º C (-103º F) in winter, not far off the Antarctic record. The tropics, on the other hand, would be pleasant in winter, and reach 45º C (113º F) in summer – unpleasantly hot, but survivably so.
The reason, the authors explain, is high cloud cover over the poles acts as a greenhouse gas.
Who knows what conditions giant worms could survive, but a species with similar thermal tolerance to humans could live with difficulty in the tropics of such a world. The mid-latitudes, however, where Herbet placed most of Arrakis' people, would kill anyone who ventured outdoors in summer.
The books describe Arrakis as a world without rain, but the model revealed occasional showers on the polar highlands in summer and autumn. This might be an understandable error for a visitor to make, but the model produced no support for references to a northern hemisphere polar ice cap. Such extreme summers would melt any ice, which would never have a chance to replenish with snow.
The model's creators are kind, however, noting the first Dune novel was written two years before the first global climate model was published. Not being biologists, however, they do not consider whether spice, or anything else, could grow in such a world.