In a bold initiative aimed at combating global warming, Professor Yoram Rozen, head of the Asher Space Research Institute (ASRI) at the Technion and a professor in the Faculty of Physics and a team of academics and industry experts has formulated a daring plan to launch a massive foil sheet into space to act as a sunshade, deflecting a portion of the sun's rays and lowering the Earth's average temperature by 1.5 degrees Celsius within a relatively short span of 18 months.
Q: From the outside, your idea sounds a bit presumptuous, Prof. Yoav Rosen: to send a shade into space that will cover part of the Earth to help deal with global warming and even lower the temperature here by a degree and a half. Tell me about your plan at the Technion.
"The idea is to send an enormous sunshade, covering an area of 2.5 million square kilometers (965,255 square miles) – roughly the size of Argentina – to a unique point between the Earth and the sun. It will unfurl between the sun and the Earth, blocking a portion of the sun's radiation and lowering the average temperature here on Earth by 1.5 degrees Celsius within a relatively short period of about a year and a half. Since we will not be able to eliminate greenhouse gas emissions entirely – and even if we do, we will still be left with the current high temperatures – we need to address the problem from the outside."
Q: It is commonly thought that since the beginning of the Industrial Age, the temperature on Earth has risen by about a degree and a half. So you're closing a gap of about 250 years in a year and a half.
Rozen acknowledges that lowering the Earth's temperature by 1.5 degrees Celsius in just 18 months is an ambitious goal, given that global temperatures have risen by approximately the same amount over the course of 250 years since the onset of the Industrial Revolution. However, he asserts, "According to all our analyses, this will work. The current average temperature on Earth is around 15 degrees Celsius, and it would be preferable to be around 13.5 degrees."
The sunshade itself would be constructed from a material already used in space missions and turns out to be relatively accessible. "It's not all that different from the survival or shock blankets used by pilots, hikers, and marathon runners to keep warm after physical exertion. It's the same material as the survival blankets you can find at Decathlon for 34 shekels (around $10)," Rozen explains. "The material is the same material – but it's clear that when sending it into space, some changes are required, and everything becomes more expensive."
Q: You're talking about a shade the size of Argentina, Algeria, or Kazakhstan. How will the production work?
While acknowledging the enormity of the task, Rozen emphasizes that the production process would be modular, with the sunshade constructed in separate components that need not be connected in space but could operate adjacently to create the desired shade. "The production will be done in parts," he clarifies. "Even in space, the components don't have to be connected; they can be side by side to create the shade."
Q: Will the shade be noticeable on Earth in any way? Will we have a shadow in the middle of the day?
"We won't feel it, and there won't be a noticeable shadow. It's a bit like a fly casting a shadow on Earth from a kilometer up. But in practice, it will lower the temperature for us, and also block 2% of the radiation that reaches us, which is the goal. The shade will mainly affect the area within 1,600 km (994 miles) from the equator, which is the critical area that affects the entire planet."
Q: How did you come up with the idea in the first place?
"The idea for the sunshade project germinated a few years ago when an Israeli group of academics and industry experts convened to explore potential solutions to global warming. While initial suggestions included launching 250 million massive (2.5 acre) balloons to shade the Earth, the group quickly recognized the impracticality of such a vast number of balloons, which could potentially fall into the atmosphere."
"A few months later, while traveling back from a conference, the idea clicked – how to send the sunshade, to what point, and what materials to use," Rozen recounts. "The next day, I discovered that someone had proposed a similar concept 16 years earlier, which gave me confidence that I was on the right track. The difference is that all the previous papers on this were theoretical, while we're coming up with a structured implementation plan."
While acknowledging the project's astronomical cost – an estimated $30 trillion – Rozen and his team have decided to start small by sending a prototype sunshade the size of a classroom into space. "After we succeed with the small one, we can enlist the world's support for the larger project," he states.
Q: When will you be able to send the prototype into space?
"Within three to four years from the moment we have the money. Sending the prototype into space will cost about $15 million. Right now, our progress is slow because we don't have money to invest, and the expectation is that in the future, we'll be able to rely on outside companies to prepare the sail, computer, and other parts."
Solar storms, pressure, and darkness
Q: You emphasize that shading the Earth must be done from outside it, i.e., from space, and that shading from the Earth's surface won't work. Could you explain that a bit more?
"On a hot sunny day in Israel, you go into an air-conditioned building. Maybe it's more comfortable for you, but you haven't changed the temperature of the Earth. If a bus stop has a roof, it's a bit more comfortable underneath it, but it doesn't change the temperature of the Earth because the roof absorbs the heat. So the shading has to be done outside the atmosphere. You need to block the radiation from reaching in the first place."
Q: The point for positioning the shade is 1.5 million kilometers (932,057 miles) from here. Why exactly?
"It's a fantastic point because it's one of five fixed points in space that rotate with the entire system. It's the only one that interests us because positioning the shade at other points would likely cast a shadow on other stars, not just us. So we have to be at the first Lagrange point, which is the distance where the gravitational forces of the Earth and the Sun are in equilibrium."
Q: What will you do about the radiation pressure?
"The radiation pressure is not negligible and knocks the system out of balance, so we'll position the shade a bit farther 'to the right,' about 50,000 km (31,069 miles) towards the Sun, to restore the system to equilibrium. By the way, the new point is also unstable, meaning the shade could still lose balance and fall. So we'll need to make corrections, just like a person standing on one leg adjusts their stance to stay upright."
Q: is the significance of such corrections in space?
"In principle, you can put an engine and make minor corrections all the time, but an engine adds weight and complexity, both of which we want to avoid. So we will deploy a sail and move to one side, or close the sail and move to the other side. The movement and reorientation won't happen every few seconds or minutes, but every 100-200 days. This is a solution that isn't problematic for us. It seems that between these two points, we can move within a certain range and stay within the area without falling. The shade will be modular and made up of many such blankets, as mentioned, and more units will be regularly launched to join the larger system."
Q: How many such launches will you need?
"We're talking about 2.5 million tons. We can currently launch 100 tons, and each time we'll launch the maximum possible. We'll likely need thousands of launches. The travel time will also be relatively short. The James Webb Space Telescope was launched about two and a half years ago to the relevant point for us, and the travel time was a few weeks."
Q: Will there be annual routine maintenance for such a project?
"There's not really an option for maintenance. Any part that fails, meaning it's in the wrong orientation, will be replaced with another. The cost of replacement is marginal compared to the entire project."
Q: What about the Sun's heating affecting the shade negatively? Just a month ago, satellites detected strong solar storms.
"It's true that the Sun has its cycles, but broadly speaking –the Sun is cooling over the course of billions of years. In a few billion years, it's also expected to go out, and then we'll need to talk again and see what we're doing."
International interest
Q: I'm trying to think about what's more presumptuous: thinking it's possible to send such a shade into space, or raising the amount of money we're talking about – $30 trillion.
"Fortunately, I'm not dealing with raising the global amount. That depends on a lot of politics."
Q: The annual US budget is about $5 trillion. I assume this is a global interest, and every country will have to contribute its share.
"To be honest, I was sure that for such a project, with keywords like sustainability, global warming, and saving planet Earth, it would be very easy to raise money – but it turns out that's not exactly the case."
Q: What kind of reactions are you getting in academia and beyond about this idea?
"Everyone is excited about it," he affirms, "but some professional bodies are skeptical about the costs. Nevertheless, technology companies, countries, and prominent environmental activists have reached out to us and expressed great interest."
However, Rozen expresses surprise at the opposition from certain environmental circles, who fear that a solution to global warming might lead to complacency about pollution. "It's important for me to note that our solution, effective as it may be, needs to coexist with the reduction of greenhouse gas emissions," he emphasizes.
Q: On the subject of opposition – how did October 7 affect your project?
"We had a major partner that left us on October 7. I'm talking about an academic institution from the United Arab Emirates, the National Space Science and Technology Center (NSSTC). They want to continue working on this project, but it's possible they were instructed to stop working with us. We visited them several times, they were our research partners and they also have a larger budget."
Q: Are you in any contact with them?
"No, they're not responding to us right now."
Q: Is there a chance they'll come back to the table?
"Yes, I'm optimistic. It's an academic institution supported by the government, and we had a great relationship that included weekly meetings that led to progress. We were supposed to visit them and present the project at the UN Climate Conference. But they told us not to come and that this project won't be in our pavilion. If the collaboration had continued, we could already be counting down to sending the prototype into space."
Q: What will happen if your plan to send this shade doesn't go through? Are there other solutions for lowering the Earth's temperature?
"Let's start from the premise that we agree the Earth's temperature is rising. As I see it, there are three branches to the solution: The first is to absorb carbon dioxide, CO2, back from the atmosphere or the oceans, thereby reducing the amount of CO2 in the atmosphere. This is possible, but we're talking about insane amounts of CO2 that we'd need to liquefy and store, and anything stored can always leak out. It's an option, but it's not without problems."
"The second solution, believe it or not – is painting everything white. The brighter an object is, the more light it reflects and doesn't absorb as heat. When you wear a black shirt you absorb more heat, while a white shirt will lower your temperature."
Q: That doesn't sound very realistic.
"Right. A sub-branch of that is to do it in space. That is, to create more clouds that reflect light and lower the temperature, but there's an extreme game with the weather here."
Q: What are the long-term risks if we don't send this shade? What could happen to the Earth over a few decades?
"I'm a physicist, not a climate scientist, but we're already witnessing more and more disasters and extreme events. If we don't address the problem, we'll see even more of them, with greater damage and a threat to our lives, within two or three decades. If we continue to allow the Earth's temperature to rise over a longer period, we could reach a point where no functioning humanity can solve its problems. It's hard to predict the future, but very negative changes could occur for humans, perhaps even irreversible ones."
Q: There are those talking about relocating humanity to another planet. Your shade solution sounds more realistic.
"If we can't live on Earth, we'll need to find another place. And relocating humanity to another planet – Mars, for example – is much more expensive than the $30 trillion we're talking about. Moreover, think about the extreme conditions on Mars: We'd have to live there in a biosphere because the radiation there is lethal and the temperature is extreme. We'd need spacesuits and a constant oxygen supply. But here, on Earth, we have great conditions, we just need to invest in solutions."
Q: It's sad, but we need a "climate October 7" for people to wake up.
"I have news for you – we're already in a 'climate October 7,' and we're not aware of it because the disaster is ongoing, not happening all at once. Fortunately, we're not annihilating 100 million people in one event, but it's happening gradually. Unfortunately, instead of focusing on a solution that will advance and improve our lives, humanity is invested in another global project that costs us much more – wars. It's so easy for us to spend money on wars, but when it comes to our future here, the expense becomes harder and more complicated. I'll never be able to understand that. We need to take action now, so we don't pay compound interest on our inaction."
