by It has come to this. With the Earth at its hottest point in recorded history, and humans doing enough to stop it from overheating, a small number of astronomers and physicists are proposing a possible solution that could have vanished from the pages of science fiction: which him and his giant beach umbrella, floating in outer space.
The idea is to create a giant sunshade and send it to a point far away between Earth and the sun to block a small but vital amount of solar radiation, enough to combat global warming. Scientists have calculated that blocking just shy of 2% of the sun’s radiation would be enough to cool the planet by 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, and keep the Earth within manageable climate limits.
The idea has been on the fringes of conversations about climate solutions for years. But as the climate crisis worsens, interest in solar shields is growing, and more researchers are offering variations. There is even a foundation dedicated to promoting sunscreens.
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A recent study led by the University of Utah explored dust spreading deep in space, and a team at the Massachusetts Institute of Technology is looking to create a shield made of “space bubbles.” Last summer, Istvan Szapudi, an astronomer at the Institute of Astronomy at the University of Hawaii, published a paper that suggested attaching a large solar shield to a repurposed asteroid.
Now scientists led by Yoram Rozen, physics professor and director of the Asher Space Research Institute at the Technion-Israel Institute of Technology, say they are ready to build a prototype umbrella to show the idea will work.
To block the necessary amount of solar radiation, the shade must be about 1 million square miles, about the size of Argentina, Rozen said. A shadow that big would be at least 2.5 million tons — too heavy to launch into space, he said. Therefore, the project would have to involve a series of smaller shades. They would not completely block sunlight but would cast a slightly diffused shadow on Earth, he said.
Rozen said his team was ready to design a 100-square-foot prototype shade and is seeking $10 million to $20 million to fund the demonstration.
“We can show the world, ‘Look, there’s a solution, take it, scale it up,'” he said.
Proponents say solar shading would not eliminate the need to stop burning coal, oil and gas, the main drivers of climate change. Even if greenhouse gas emissions from fossil fuels were to immediately drop to zero, there is already too much heat-trapping carbon dioxide in the atmosphere.
The Earth’s average temperature is set to rise by 1.5 Celsius above the pre-industrial average. That’s the point where the chance of extreme storms, drought, heat waves and wildfires would increase significantly and people and other species would struggle more to survive, scientists say. The planet has already warmed 1.2 degrees Celsius.
Solar shade would help stabilize the climate, according to supporters of the idea, while other climate mitigation strategies are pursued.
“I’m not saying this is the solution, but I think everyone has to work towards all possible solutions,” said Szapudi, the astronomer who suggested attaching a sunshade to an asteroid.
It was 1989 when James Early of the Lawrence Livermore National Laboratory proposed a “space-based solar shield” located near a fixed point between Earth and the sun called Lagrange Point One, or L1, about 932,000 miles away, four times the mean distance . between the Earth and the moon. Then, gravity pulls from the Earth and the sun cancels each other out.
In 2006, Roger Angel, an astronomer at the University of Arizona, presented his proposal for a defective solar shield at the National Academy of Sciences and later won a grant from NASA’s Institute for Advanced Concepts to continue his research. He proposed launching a trillion very light spacecraft at L1, using transparent film and steering technology that would prevent the devices from drifting into orbit.
“It’s just like you’ve just knocked on the sun,” Angel said, “and you’re not bothered by the atmosphere.”
The sunshade idea has critics, including Susanne Baur, a doctoral candidate focusing on modeling solar radiation modulation at the European Center for Research and Advanced Training in Scientific Computing in France. The sunshade would be astronomically expensive and could not be implemented in time, given the pace of global warming, she said. In addition, a solar storm or collision with stray space rocks could damage the shield, leading to rapid, rapid heating with catastrophic consequences, Baur said.
Time and money would be better spent working to reduce greenhouse gas emissions and remove carbon dioxide from the atmosphere, she said, with a small amount of research focused on “more viable and cost-effective” solar geoengineering ideas “.
But proponents of the sun’s shadow say that reducing greenhouse gas emissions will not go far enough to alleviate climate chaos at this stage, that carbon dioxide is extremely difficult to achieve and that all possible solutions should be explored.
A fully operational sunshade would have to be resilient and reversible, Szapudi said. In his proposed design, he said 99% of its weight would come from the asteroid, helping to offset the cost. It would still likely carry a trillion-dollar price tag, an amount far less than what is spent on military weapons, he said.
“Saving the Earth and giving up 10% of your weapons to destroy things is a pretty good deal in my book,” Szapudi said.
He said Tesla was an example of an idea that once seemed wildly ambitious but within 20 years of its founding became the world’s leading electric vehicle manufacturer.
Morgan Goodwin, executive director of the Planetary Sunshade Foundation, a non-profit organization, said one reason sunshades haven’t gained as much traction is that climate researchers have naturally focused on what’s happening inside the Earth’s atmosphere and not on the space.
But the reduced costs of space launches and investments in an industrial space economy have increased possibilities, Goodwin said. The foundation proposes using raw materials from space and sending a sunshade ship into L1 from the moon, which would cost much less than going from Earth.
“We think that as climate people understand the idea of sunshades, it will become an obvious part of the discussion,” said Goodwin, who is also senior director of the Angeles chapter of the Sierra Club.
The Technion model involves attaching a light solar sail to a small satellite sent to L1. His prototype would move back and forth between L1 and another balance point, with the sail tilting between pointing at the sun and being perpendicular to it, moving like a rod on a Venetian blind. This would help keep the satellite stable and eliminate the need for a propulsion system, Rozen said.
Rozen said the team was still in the preliminary design phase but could launch a prototype within three years after receiving funds. He estimated that a full-scale version would cost trillions (a tab “for the world to pick up, not just one country,” he said) but would reduce the Earth’s temperature by 1.5 Celsius within two years.
“We are not at the Technion to save the planet,” Rozen said. “But we’re going to show it can be done.”
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