Since we're past the point where emissions cuts alone can keep long term warming below 2 C, I do expect active geoengineering efforts later this century. Solar radiation management with aerosols is not a long term fix but could keep positive feedback effects damped while slower long term fixes (like emissions reduction plus accelerated silicate weathering) roll out.<p>The attractive thing about sulfate aerosols is that they could be formed from sulfur dioxide, which is cheap to form via sulfur combustion and disperses excellently because it's a gas. Delayed oxidation reactions cause SO2 to form nuclei for aerosols. Even though calcium carbonate is also inexpensive, I don't think there is a comparably cheap/easy way to deliver a fluid precursor for it to the upper atmosphere. The closest I can think of is aerosolizing a calcium hydroxide solution that would carbonate <i>in situ</i> via reaction with atmospheric CO2... but calcium hydroxide is only slightly soluble in water. You'd need to lift a lot of extra water mass.
another naive article, this time from Harvard, that fails to mention the term "ocean acidification". At some point krill cannot form their exoskeletons, bringing an abrupt end to whales and other sea creatures.