Should We Fight Climate Change by Releasing Sulfur Dioxide into the Stratosphere?

A professor in the University of Chicago's department of geophysical sciences "believes that by intentionally releasing sulfur dioxide into the stratosphere, it would be possible to lower temperatures worldwide," reports the New York Times. He's not the only one promoting the idea. "Harvard University has a solar geoengineering program that has received grants from Microsoft co-founder Bill Gates, the Alfred P. Sloan Foundation and the William and Flora Hewlett Foundation. It's being studied by the Environmental Defense Fund along with the World Climate Research Program.... But many scientists and environmentalists fear that it could result in unpredictable calamities."Because it would be used in the stratosphere and not limited to a particular area, solar geoengineering could affect the whole world, possibly scrambling natural systems, like creating rain in one arid region while drying out the monsoon season elsewhere. Opponents worry it would distract from the urgent work of transitioning away from fossil fuels. They object to intentionally releasing sulfur dioxide, a pollutant that would eventually move from the stratosphere to ground level, where it can irritate the skin, eyes, nose and throat and can cause respiratory problems. And they fear that once begun, a solar geoengineering program would be difficult to stop... Keith, a professor in the University of Chicago's department of geophysical sciences, countered that the risks posed by solar geoengineering are well understood, not as severe as portrayed by critics and dwarfed by the potential benefits. If the technique slowed the warming of the planet by even just 1 degree Celsius, or 1.8 degrees Fahrenheit, over the next century, Keith said, it could help prevent millions of heat-related deaths each decade... Opponents of solar geoengineering cite several main risks. They say it could create a "moral hazard," mistakenly giving people the impression that it is not necessary to rapidly reduce fossil fuel emissions. The second main concern has to do with unintended consequences. "This is a really dangerous path to go down," said Beatrice Rindevall, the chair of the Swedish Society for Nature Conservation, which opposed the experiment. "It could shock the climate system, could alter hydrological cycles and could exacerbate extreme weather and climate instability." And once solar geoengineering began to cool the planet, stopping the effort abruptly could result in a sudden rise in temperatures, a phenomenon known as "termination shock." The planet could experience "potentially massive temperature rise in an unprepared world over a matter of five to 10 years, hitting the Earth's climate with something that it probably hasn't seen since the dinosaur-killing impactor," Pierrehumbert said. On top of all this, there are fears about rogue actors using solar geoengineering and concerns that the technology could be weaponized. Not to mention the fact that sulfur dioxide can harm human health. Keith is adamant that those fears are overblown. And while there would be some additional air pollution, he claims the risk is negligible compared to the benefits. The opposition is making it hard to even conduct tests, according to the article - like when Keith "wanted to release a few pounds of mineral dust at an altitude of roughly 20 kilometers and track how the dust behaved as it floated across the sky." The experiment was called off after opposition from numerous groups - including Greta Thunberg and an organization representing Indigenous people who felt the experiment was disrespecting nature.

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