If possible, remove CO2 in the atmosphere and storing it in a stable state underground [...] what I would class as planet-level terraforming, and is going to ta

If possible, remove CO2 in the atmosphere and storing it in a stable state underground [...] what I would class as planet-level terraforming, and is going to take more than just Elon (without some sort of additional technological breakthrough). We already have nanomachines that work in harmony to do this: tree-and-mushroom networks (among other organisms) known as forests. I wish there was something like http://www.treesforthefuture.org/ http://www.treesforthefuture.org/ but commercial that I could invest in.