Elon Musk, who leads the U.S. private space company SpaceX, has put forward a claim to launch a large number of satellites in Earth orbit that would act as mirrors, reflecting sunlight back into space and thereby stopping global warming.

Proposals to artificially reflect sunlight can disrupt the Earth climate system, so the mainstream scientific community treats discussion of them as taboo. Yet because Musk wields formidable political and economic clout, his raising of such an idea is drawing attention to whether related technologies could become reality.

On the 3rd (local time), Musk posted on his X account, stating that “an artificial intelligence (AI) based large-scale satellite constellation could finely modulate the amount of solar energy reaching Earth and thereby stop global warming”.

His post appears to argue for launching many satellites that act as mirrors in Earth orbit to reduce the amount of solar energy reaching the surface. Academia refers to this as ‘solar radiation management (SRM)’.

SRM stems from the assessment that global warming is tipping into an uncontrollable stage. Because national interests are keeping carbon dioxide from falling quickly, the idea is to reduce the very solar energy that reaches the surface. Some in academia have proposed massively injecting aerosols (fine particles) into the atmosphere of Earth or spreading sunlight-reflective materials on land and sea. It is a short-term response for defending against warming.

However, SRM has problems. When sunlight reaching the surface is artificially reduced, it is not possible to predict exactly how the Earth climate system will respond. This is because the climate system is extremely complex. Blocking sunlight to lower temperatures in some regions could bring unprecedented natural disasters to others.

If SRM were to be implemented, the question of who would have what authority to block sunlight over particular regions also comes to the fore. A country that suffers unintended impacts due to SRM could push back.

In fact, on X, under the SRM-related proposal that Musk posted that day, there was also a comment stating that there is “a possibility of geopolitical conflict”. Because of such issues, there is a strong tendency in the mainstream scientific community to treat discussion of SRM itself as taboo. As a result, none of the related technologies has reached commercialization.

Yet the fact that Musk is the richest person in the world and the chief executive officer (CEO) of SpaceX, which possesses cutting-edge launch vehicle and satellite manufacturing technology, is a variable. SpaceX has launched as many as 10,000 satellites from 2019 through this year for the purpose of ‘Starlink’, which provides internet service worldwide. Across all nations and companies, no organization other than SpaceX has put so many satellites into orbit in human history.

In other words, SpaceX may have the potential to turn the idea of Musk into reality. For that reason, the local scientific community is watching closely to see what moves Musk will make following this proposal.