Scientists explore giant sunshade to cool Earth

The concept involves placing thousands of reflective satellites or a cloud of particles between Earth and the Sun to block a small amount of sunlight. A new report by the nonprofit Planetary Sunshade Institute suggests that construction could begin within 20 to 40 years, depending on advances in heavy-lift rockets.

The idea has gained attention as global temperatures continue to rise. In August, SpaceX CEO Elon Musk suggested on X that satellites could shade Earth from sunlight and help solve global warming.

However, scientists remain divided over whether the technology is practical.

The report, funded by a £400,000 grant from the UK Advanced Research and Invention Agency, examines six possible designs for a space-based sunshade. It estimates that blocking about 1% of the sunlight reaching Earth could lower global temperatures by approximately 1°C.

One proposal involves deploying around 5,000 giant rotating satellites, each about 40 kilometers in diameter. Together, they would require nearly 70 million tonnes of material, about 1,500 times the total mass of everything previously launched into space.

Building such a system would require launching satellite components from Earth and assembling them in space. The report suggests using materials mined from the Moon to reduce the cost of transporting heavy equipment into space.

Another proposal would create a cloud of reflective dust or specially designed particles between Earth and the Sun. This approach could require hundreds of times less material than the satellite system, but researchers consider it more speculative.

Both designs would be placed about 2 million kilometers from Earth, where they could block sunlight before it reaches the planet.

The technology also raises concerns. Thousands of rocket launches could cause significant pollution, while the long-term effects of space-based sunshades remain uncertain. Critics warn that focusing on such projects could distract governments from cutting greenhouse gas emissions, the main driver of global warming.

The cost is another major obstacle. The report says there is not enough information to produce a reliable estimate, but engineer Chantal Cappelletti of the University of Nottingham suggests that a planetary sunshade could cost tens of trillions of dollars.

Earlier, Qazinform News Agency reported that climate change was linked to more than half of heat-related deaths in Europe.