Can we turn the world’s deserts green? CrowdScience listener Youcef is captivated by the idea of bringing water back to Earth’s driest landscapes. With sea levels rising and huge stretches of land drying out each year, he wonders whether redirecting seawater inland could offer a solution to both problems. Presenter Alex Lathbridge sets out to investigate starting with a kettle of salty water. Alex speaks to scientists about how deserts form, and how human actions like overgrazing can tip a fragile grassland into a barren landscape. He learns how the brightness of bare sand affects local weather, reducing cloud formation and rainfall. Researcher Yan Li reveals how huge solar and wind farms could darken and roughen the Sahara’s surface enough to double its rainfall, potentially kickstarting a self-reinforcing cycle of vegetation and moisture. But what about deserts where clouds already drift overhead? In the Atacama, one of the driest places on Earth, geographer Virginia Carter shows how fog harvesting nets can coax litres of fresh water from the air. Alex also investigates desalination, where professor Chris Sansom is trying to harness solar power to remove the salt from seawater without burning vast amounts of fossil fuels. It is promising, but can it reduce the impact of rising sea levels? And what do you do with all the salt that’s left over? Climate scientist Alan Condron proposes an even wilder idea: towing kilometre-sized icebergs from Antarctica to parched nations. His models show it might be possible, but the logistics verge on science fiction. Finally, plant scientist Zinnia Gonzalez Carranza warns that greening deserts isn’t just about adding water. Introducing new species, even hardy ones like mesquite, can trigger ecological chaos and harm the very communities who depend on these landscapes. Presenter: Alex Lathbridge
Producer: Sam Baker
Editor: Ben Motley (Photo: Palm trees growing in cracked, parched earth and the sun rising behind them. Credit: Danymages/Getty Images)

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