Aircraft able to carry such loads at that altitude have not yet been built. But it is calculated the process would have similar results to volcanic eruptions, such as that of Mount Pinatubo in the Philippines in 1991, the clouds of material from which led to mean global cooling of 0.3℃ to 0.5℃ for the following two years, according to the UN Environment Programme.
Other methods being researched include thinning cirrus clouds to allow more infrared rays to leave the atmosphere, and launching sunshades into space.
The EU text, which is not legally binding and could still change before publication, shows the extent of concern that humanity will not be able to keep global warming within the targeted 1.5℃ limit.
Geo-engineering can also refer to carbon capture and storage, which is being scaled up as a means of take emissions out of the air.
All these methods, which are still in embryonic stages of development, remain ungoverned. An effort - led by Switzerland and backed by a dozen countries including Mexico, Burkina Faso and South Korea - to have a resolution on assessing geo-engineering technologies adopted at the UN Environment Assembly failed in 2019.
In its most recent report on so-called “solar radiation management” - which encompasses different techniques for adjusting the sun’s rays - the UN Environment Programme described the technology as the “only” way to cool the planet in the short term.
But, the authors warned, several factors, including costs that could run into “tens of billions of US dollars per year per 1℃ cooling”, made medium to large-scale deployment “unwise”.
Interfering in the globe’s natural climate could damage the ozone layer, redistribute the impact of climate change across ecosystems, cause geopolitical tensions and, if suddenly stopped, cause a sudden recurrence of global warming that would be sharper and more dangerous, the report warned.
Scientists are also keen to underline that weather-altering technologies should not take away from efforts to cut greenhouse gas emissions overall.
Matthias Honegger, a senior researcher at Perspectives Climate Research, said that if a country decided to deploy methods to alter the sun’s rays it could achieve it “within a few years”, which is “why there is such an emphasis to rapid research into this”.
The governing principle of current research was that “you need to establish beyond reasonable doubt that it is not extremely dangerous”. He added that the commission focusing solely on potential risks was “unfortunate...when [its] very raison d’être is to limit harm and suffering from ever-growing climate impacts”.
The commission declined to comment on the draft document.
© Financial Times