A group of scientists and governance scholars have signed a letter urging an agreement not to allow or undertake projects that seek to "block out" the Sun.
Every now and then, some scientists (or Monty Burns) suggest blocking out the sun. The idea, called solar geoengineering, is basically to cool the planet by reducing the sunlight that makes it down to Earth.
In practice, scientists suggest less dramatic methods than Mr Burns – think sending sunlight-reflecting small molecules into the upper atmosphere rather than erecting a big metal sun blocker – but the projects are often met with more than a few concerns about the risks. Joining these critics of the idea, 46 scientists and governance experts wrote an open letter explaining why they believe the risks outweigh the rewards.
"The risks of solar geoengineering are poorly understood and can never be fully known," the signatories wrote in their letter. "Impacts will vary across regions, and there are uncertainties about the effects on weather patterns, agriculture, and the provision of basic needs of food and water."
They write that with no international agreements on how solar geoengineering projects would be implemented, it is likely that a few powerful countries could begin implementing it against the wishes of the international community – including poorer countries that could be impacted more (e.g. by concerns over growing food).
They also believe that any commitments to the project could disincentivize governments, businesses, and societies from doing everything they can to reduce carbon emissions, believing that a technological "fix" could become available in the future.
"The speculative possibility of future solar geoengineering risks becoming a powerful argument for industry lobbyists, climate denialists, and some governments to delay decarbonisation policies," they added.
The letter calls for an "International Non-Use Agreement on Solar Geoengineering". They call on governments to prevent national funding supporting the development of technologies for solar geoengineering, ban experiments of such technologies, and not allow patents relating to such technologies.
They also call for governments not to use tech that has been developed elsewhere (e.g. in a country not signed up to the agreement), and to commit to opposing solar geoengineering as a policy option in all other relevant international institutions.
Though the tech is different, the letter says that the idea of banning such technology is by no means the first.
"International political control over the development of contested, high-stakes technologies with planetary risks is not unprecedented. The international community has a rich history of international restrictions and moratoria over activities and technologies judged to be too dangerous or undesirable," they write.
"This history demonstrates that international bans on the development of specific technologies do not limit legitimate research or stifle scientific innovation. In addition, an International Non-Use Agreement on Solar Geoengineering could include exceptions for less dangerous approaches, for example by allowing the use of localised surface albedo-related technologies that pose few cross-regional or global risks."