I would offer that a lot of proposals like Project Vesta sound great, but are massive-scale geo-engineering projects that could, themselves, have unintended consequences.
A volume of 7 cubic miles (11 km^3) of olivine, or around 30 Gigatons, is needed each year. This is less than half the volume of construction materials and less than that of fossil fuel equivalents mined yearly.
That's gigantic, how can they sustain that 30 gigatons a year ?
