Giant Parasol: Newest GeoEngineering Idea is Throwin’ Shade

Sure, that ought’a work.

See, doomers? Simple fix.

New York Times:

It’s come to this. With Earth at its hottest point in recorded history, and humans doing far from enough to stop its overheating, a small but growing number of astronomers and physicists are proposing a potential fix that could have leaped from the pages of science fiction: The equivalent of a giant beach umbrella, floating in outer space.

The idea is to create a huge sunshade and send it to a far away point between the Earth and the sun to block a small but crucial amount of solar radiation, enough to counter global warming. Scientists have calculated that if just shy of 2 percent of the sun’s radiation is blocked, that would be enough to cool the planet by 1.5 degrees Celsius, or 2.7 Fahrenheit, and keep Earth within manageable climate boundaries.

The idea has been at the outer fringes of conversations about climate solutions for years. But as the climate crisis worsens, interest in sun shields has been gaining momentum, with more researchers offering up variations. There’s even a foundation dedicated to promoting solar shields.

A recent study led by the University of Utah explored scattering dust deep into space, while a team at the Massachusetts Institute of Technology is looking into creating a shield made of “space bubbles.” Last summer, Istvan Szapudi, an astronomer at the Institute for Astronomy at the University of Hawaii, published a paper that suggested tethering a big solar shield to a repurposed asteroid.

Now scientists led by Yoram Rozen, a physics professor and the director of the Asher Space Research Institute at Technion-Israel Institute of Technology, say they are ready to build a prototype shade to show that the idea will work.

To block the necessary amount of solar radiation, the shade would have to be about a million square miles, roughly the size of Argentina, Dr. Rozen said. A shade that big would weigh at least 2.5 million tons — too heavy to launch into space, he said. So, the project would have to involve a series of smaller shades. They would not completely block the sun’s light but rather cast slightly diffused shade onto Earth, he said.

Dr. Rozen said his team was ready to design a prototype shade of 100 square feet and is seeking between $10 million and $20 million to fund the demonstration.

“We can show the world, ‘Look, there is a working solution, take it, increase it to the necessary size,’” he said.

Proponents say that a sunshade 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’s already excessive heat-trapping carbon dioxide in the atmosphere.
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“I’m not saying this will be the solution, but I think everybody has to work toward every possible solution,” said Dr. Szapudi, the astronomer who proposed tethering a sunshade to an asteroid.

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University of Hawaii:

One of the simplest approaches to reducing the global temperature is to shade the Earth from a fraction of the Sun’s light. This idea, called a solar shield, has been proposed before, but the large amount of weight needed to make a shield massive enough to balance gravitational forces and prevent solar radiation pressure from blowing it away makes even the lightest materials prohibitively expensive. Szapudi’s creative solution consists of two innovations: a tethered counterweight instead of just a massive shield, resulting in making the total mass more than 100 times less, and the use of a captured asteroid as the counterweight to avoid launching most of the mass from Earth.

“In Hawaiʻi, many use an umbrella to block the sunlight as they walk about during the day. I was thinking, could we do the same for Earth and thereby mitigate the impending catastrophe of climate change?” Szapudi said.

Szapudi began with the goal of reducing solar radiation by 1.7%, an estimate of the amount needed to prevent a catastrophic rise in global temperatures. He found that placing a tethered counterbalance toward the Sun could reduce the weight of the shield and counterweight to approximately 3.5 million tons, about one hundred times lighter than previous estimates for an untethered shield.

While this number is still far beyond current launch capabilities, only 1% of the weight—about 35,000 tons—would be the shield itself, and that is the only part that needs to be launched from Earth. With newer, lighter materials, the mass of the shield can be reduced even further. The remaining 99% of the total mass would be asteroids or lunar dust used as a counterweight. Such a tethered structure would be faster and cheaper to build and deploy than other shield designs.

Today’s largest rockets can only lift about 50 tons to low Earth orbit, so this approach to solar radiation management would be challenging. Szapudi’s approach brings the idea into the realm of possibility, even with today’s technology, whereas prior concepts were completely unachievable. Also, developing a light-weight but strong graphene tether connecting the shield with the counterweight is crucial.