Israeli researchers want to build a space parasol to cool Earth, mitigate global warming

Scientists have confirmed that 2023 was the hottest year on record; projections suggest this year might be even hotter.

As climate change threatens livability and increases the likelihood of natural disasters, some aerospace engineers and physicists, including an Israeli researcher, propose a solution: a giant parasol in space to shade the planet.

Prof. Yoram Rozen, director of the Asher Space Research Institute at Technion-Israel Institute of Technology, explained that the idea is to design a sunshade and position it strategically between Earth and the sun to block enough solar radiation to mitigate global warming.

The ability to return to pre-Industrial Revolution temperatures

Rozen suggested that blocking just 2% of the sun’s radiation could cool the planet by 1.5 degrees Celsius, returning us to pre-Industrial Revolution temperatures.

Rozen and his team say scientists already have “all the pieces needed” to create such a shade. Therefore, they plan to build a prototype that proves this.

Rozen told The Jerusalem Post that it would take $10 million to $20m. and about three years to build a 10-square-meter prototype. Then, the plan would be to send it into space to a point called “Lagrange 1” or “L1.” Lagrange points are “positions where the gravitational pull of two large masses precisely equals the centripetal force required for a small object to move with them,” NASA explained on its website.

The points are named for Italian-French mathematician Joseph-Louis Lagrange.

Rozen explained that a satellite or rocket could launch the prototype into space. Once deployed, the parasol would oscillate between the L1 point and another, nearby equilibrium point. The sail would adjust its angle, alternating between facing the sun directly and being perpendicular to it every three or four months. This movement strategy would maintain satellite stability without requiring a propulsion system.

Rozen added that the parasol could be made of any lightweight, weather-resistant fabric, like those blankets given to marathon runners.

The prototype would be a partial solution. According to Rozen, to get the job done, such a shade – or an ensemble of smaller shades – would need to be around 2.5 million square kilometers and something invested in by the whole world, not just the Technion.

“Why do we have a problem with global warming?” Rozen asked. “The sun is heating the air all the time – for billions of years. Earth has to get rid of the heat, or it will heat and heat endlessly. So, it radiates it out.”

But since the Industrial Revolution, and especially in the last few decades, Rozen explained, an increase in greenhouse gases has impeded heat loss from Earth’s atmosphere to space.

“Now, temperatures are 1.2 to 1.3 degrees higher than we want them to be, and the result is what we see happening with our weather,” Rozen said. “We want the temperatures to go back a bit.

“Even if we completely stop emissions – let’s say there is not a single car on the road, no flights, no cows – we will stay at the current temperature, which is pretty bad,” Rozen continued. “We don’t think making a sunshade will be too difficult. We think we have a solution.”

ROZEN’S TEAM are just some of the scientists who have proposed sunshade solutions. In 2021, for example, Swedish scientists published a paper titled “Realistic Sunshade System at L1 for Global Temperature Control,” suggesting that sunshades could be constructed on Earth using future solar sail technology and reach the L1 point within two years through solar sailing. They estimated the cost to be a few trillion dollars.

There was also a similar suggestion by American researcher Robert Angel in 2006, who wrote the “Feasibility of cooling the Earth with a cloud of small spacecraft near the inner Lagrange point (L1).”

There is even a foundation called the Planetary Society focused on how to shade Earth, which has also examined the possibility of space parasols.

However, scientists at Wichita State University recently pushed back on the idea.

“You hear a lot of big-name people talking about some ideas, like, ‘Let’s have a space shield to block out some of the sun – cool the planet with some shadows,’” said Dr. Nickolas Solomey in an article published over the weekend on the Wichita State University website. “From a science point of view, there are some questions.”  

Working with graduate student Kelly Kabler, Solomey calculated that to cool the Earth by 1.5 degrees Celsius, a 10% to 15% reduction in sunlight would be necessary. Rozen’s shade would only reduce sunlight by around 2%.

Kabler calculated that the shade would need to be around 900 miles (1450 km.) wide and would take between 12 and 15 years to achieve its goal – and the effects of the shade would only last up to 60 years.  

The Wichita research will be presented next month at the Innovation in Climate Resilience conference in Washington.

“The final answer was that [a sunshade] is not totally plausible as the sole mechanism for slowing down climate change. There would have to be other things that come into play to help with it,” Kabler said. “It’s not very practical.”