There are significant and well-known risks to some of these techniques — sulfur dioxide aerosol injection, in particular.
First, spraying sulfur into the atmosphere will “mess with the ozone chemistry in a way that might delay the recovery of the ozone layer,” Parson told CNBC.
The Montreal Protocol adopted in 1987 regulates and phases out the use of ozone depleting substances, such as hydrochlorofluorocarbons (HCFCs) which were commonly used in refrigeration and air conditioners, but that healing process is still going on.
Also, sulfates injected into the atmosphere eventually come down as acid rain, which affects soil, water reservoirs, and local ecosystems.
Third, the sulfur in the atmosphere forms very fine particulates that can cause respiratory illness.
The question, then, is whether these known effects are more or less harmful than the warming they would offset.
“Yes, damaging the ozone is bad, acid deposition is bad, respiratory illness is bad, absolutely. And spraying sulfur in the stratosphere would contribute in the bad direction to all of those effects,” Parson told CNBC. “But you also have to ask, how much and relative to what?”
The sulfur already being emitted from the burning of fossil fuels is causing environmental damage and is already killing between 10 million to 20 million people a year due to respiratory illness, said Parson. “So that’s the way we live already,” he said.
Meanwhile, “the world is getting hotter, and there will be catastrophic impacts for many people in the world,” said Pasztor.
“There’s already too much carbon out there. And even if you stop all emissions today, the global temperature will still be high and will remain high for hundreds of years. So, that’s why scientists are saying maybe we need something else, in addition — not instead of — but maybe in addition to everything else that is being done,” he said. “The current action/nonaction of countries collectively — we are committing millions of people to death. That’s what we’re doing.”
For sunlight-reflection technology to become a tool in the climate change mitigation toolbox, awareness among the public and lawmakers has to grow slowly and steadily, according to Tyler Felgenhauer, a researcher at Duke University who studies public policy and risk.
“If it is to rise on to the agenda, it’ll be kind of an evolutionary development where more and more environmental groups are willing to state publicly that they’re for research,” Felgenhauer told CNBC. “We’re arguing it’s not going to be some sort of one big, bad climate event that makes us all suddenly adopt or be open to solar geoengineering — there will be more of a gradual process.”
Article source: https://www.cnbc.com/2022/10/13/what-is-solar-geoengineering-sunlight-reflection-risks-and-benefits.html