As engineers and scientists around the world look to new technologies to help cool the planet, one research team believes that the answer could lie in abundant calcium carbonate.
Reuters last week profiled a series of efforts to limit a warming climate as experts warn that simply curbing emissions of carbon dioxide and other greenhouse gases won't be enough to meet the goals set in the Paris climate agreement.
Some scientists pinned their hopes on directly capturing carbon dioxide from the atmosphere, but that process is currently inefficient and costly, and experts warn that it wouldn't resolve the underlying issue of excessive emissions.
Others believe in efforts to alter the environment to reduce carbon — projects known as "geo-engineering."
One initiative, established by Harvard University researchers last year, raised $7.5 million in private contributions and is preparing for its initial experiment.
The team plans to float a balloon high above Arizona next year and release just more than two pounds of calcium carbonate or a similar chemical.
Although small-scale, the experiment will seek to determine how those particles affect the stratosphere — with the hope that they could, in effect, dim sunlight and reduce warming.
"I don't think it's science fiction," Harvard physicist David Keith told Reuters. "To me, it's normal atmospheric science."
Other potential geo-engineering projects could include creating more clouds or soaking up carbon in the oceans with iron.
Skeptics, however, warn that those ideas come with greater risks. Altering sunlight, for example, could interrupt crucial global weather patterns such as monsoons.
Oxford University physicist Raymond Pierrehumbert told the publication that although carbon capture systems deserved additional attention, geo-engineering, by contrast, seems "barking mad."