As the planet bakes, scientists are putting forward increasingly outlandish ideas to curb climate change. The latest: a gigantic shield between the sun and the Earth that blocks out the heat. Just because the idea is far-out doesn’t mean it wouldn’t work. That’s the takeaway of a study published Monday in the journal Proceedings of the National Academy of Sciences, writes Chelsea Harvey. The idea is simple in theory. A massive, reflective sunshade built between Earth and the sun could help cool the planet by blocking out some incoming solar radiation. In fact, engineer James Early first proposed a version of the plan in 1989, and it's been bouncing around the fringes of climate geoengineering conversations ever since. The new study by theoretical cosmologist István Szapudi is reviving the idea by proposing a potential solution to one of the sunshade’s major problems: its weight. It’s so heavy To avoid being dislodged from space, scientists concluded the sunshade would need to weigh at least a few million metric tons — for reference, the Hoover Dam comes in at 6.6 million metric tons. Something that huge could be expensive, time-consuming and a nightmare to transport. But Szapudi, who is based at the University of Hawaii, found that it's theoretically possible to build a smaller shield and tether it to a heavy counterweight, such as an asteroid, to hold it in place. With a sufficient counterweight, Szapudi estimates the sunshade could be as light as 35,000 metric tons and still block out enough radiation to meet the Paris Agreement’s climate goals. Reality check Still, it would take “an army of engineers” to prove whether the sunshade is feasible in real life, Szapudi said. And like with most climate geoengineering proposals, the associated risks could be devastating. For example, the idea of spraying aerosols into the atmosphere to deflect the sun’s rays has gained increased attention in recent months. But scientists worry that such a move could affect precipitation and other global weather patterns, while possibly damaging the Earth's ozone layer. While such ideas are, for now, just ideas, they keep on coming — underscoring the mammoth nature of the climate crisis and scientists’ growing desperation to find a solution in a world that isn’t cutting emissions fast enough to stave off catastrophe.
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