Yahoo News Could spraying chemicals into the atmosphere really stop or reverse global warming?
It’s an idea straight out of science fiction – 'blocking the sun' to cool the atmosphere and curb or even reverse climate change.
But research has shown that the hugely controversial idea of solar geoengineering – using technology to mitigate the effects of global warming – could possibly prevent catastrophic sea level rises, by slowing melting in West Antarctica.
Lead author Paul Goddard, an assistant research scientist in the Indiana University College of Arts and Sciences's Department of Earth and Atmospheric Sciences, said: "Even if the world meets the ambitious target of limiting global warming to 1.5C above pre-industrial levels – which we are not on track to do – we are going to see significant sea-level rise.
"Exploring ways to reflect sunlight into space before it is absorbed into Earth's climate system could help buy us more time to address climate change and avoid or delay climate tipping points, such as the collapse of the West Antarctic Ice Sheet."
The study explored a form of climate engineering called stratospheric aerosol injection, in which large amounts of tiny sulphur droplets are released into the stratosphere by a fleet of aeroplanes.
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The approach mimics what happens when a large volcano spews vast amounts of particles into the upper atmosphere and precipitates a cooling effect that can last months to years.
It was recently discussed in a White House report outlining a potential research programme on stratospheric aerosol injection and marine cloud brightening, another proposed strategy for cooling the planet.
The researchers used high-performance computers and global climate models to simulate different stratospheric aerosol injection scenarios.
"Where you release the aerosols matters a lot and can affect the climate differently," Goddard said.
"In this case, we found that releasing stratospheric aerosols at multiple latitudes within the tropics and sub-tropics, with a greater proportion in the Southern Hemisphere, is the best strategy for preserving land ice in Antarctica because it helps keep warm ocean waters away from the ice shelves."
Researchers simulated 11 different stratospheric aerosol injection scenarios, but further study is needed to quantify the change in melt rates, Goddard said.
Notably, several single-latitude injection scenarios actually accelerated Antarctic ice loss due to a southward shift of prevailing winds drawing warm ocean waters toward the ice shelves.
"If we're ever going to engineer the climate, how we do it really matters," Goddard added.
"If society decides it wants to do geoengineering someday, we need to better understand what we know and what we don't know.
"We're starting to fill some of these knowledge gaps on the risks and regional effects of managing solar radiation, but there's a lot more research that needs to be done before anyone can say whether it's a good idea to actually move forward with it.
"That's true as much for Antarctica as it is for the rest of the planet."
What is solar geoengineering – and who backs it?
The idea of solar geoengineering – using technology to reflect the sun's rays away from Earth – is hugely popular among billionaires.
George Soros spoke of brightening clouds above the Arctic to protect melting ice caps, while Bill Gates backed a Harvard project to test the idea of flying jets into the atmosphere on thousands of missions to release carbonate dust.
What are the risks?
Some of the risks related to stratospheric aerosol injection include the possibility of "termination shock", a rapid rebound of global temperatures to pre-stratospheric aerosols injection levels should the decades-long treatment be interrupted.
Geoengineering could also change weather patterns around the world.
In 2022, 60 scientists signed an open letter calling for an international non-use agreement on solar geoengineering technology, which was published in the journal WIRE Climate Change.
How would it work?
Most plans for solar engineering involve improving the reflectance of the sun's rays – either using large mirrors in space, ground-based reflectors or using cloud 'mirrors' or aerosols sprayed into the atmosphere.
Other plans involve capturing carbon dioxide directly from the atmosphere.
A Gates-funded Harvard project, which was eventually called off after protests, planned a fleet of specially-designed aircraft that could spray sulphate particles into the lower stratosphere to cool the planet.
But a balloon test to pave the way for the project – Stratospheric Controlled Perturbation Experiment (SCoPEx) – was cancelled after protests warning of "catastrophic consequences".
The researchers had envisaged a plan where planes flying 12 miles up would complete over 60,000 missions dispensing dust into the atmosphere.
