A form of geoengineering is seeding Fe and P into appropriate places (good currents) of the ocean. This kickstarts aquatic life and removes carbon fast ... and as a by product creates whole new fisheries. It is fast and cheap enough that small countries and multimillionaires (and up) can do it as a DIY solution to climate change ... so why has this not been done, forcefully? There seems to be tremendous social opprobrium! A ~proof of concept has already been done.
~proof of concept
https://www.vox.com/the-highlight/2019/5/24/18273198/climate...