Can geoengineering stop global warming?

The worst effects of climate change could be safely curbed by spraying sun-reflecting chemicals into the high atmosphere, a new U.S. study suggests. Scientists have long wondered if it might be possible to artificially cool the planet by blocking some of the sun’s rays with sulfate aerosols— chemicals naturally spewed into the atmosphere by volcanic eruptions—if humanity fails to cut carbon emissions sufficiently to halt the planet’s warming. But some researchers have warned that “solar geoengineering” could further disrupt Earth’s climate, weakening the monsoon and triggering droughts in Asia and Africa.

For this new study, scientists used computer models to gauge whether there was a perfect “dose” of sun-blocking aerosols that could slow warming without any adverse side effects. They concluded that if the process were used to eliminate only half of warming, rather than all of it, only 0.4 percent of the inhabited world would see the effects of climate change worsen. Other environmental scientists remain skeptical, reports They note that the study didn’t actually model what happens when sulfate aerosols are injected into the atmosphere, but only the effect of reducing the strength of the sun’s rays. Co-author David Keith, a Harvard physicist, says the study simply shows that “solar geoengineering could be really useful” and should be seriously investigated by an international scientific panel.