A Thought on Carbon Capture and Storage

They mentioned storage in geological formations deep underground. This speaks of a fundamental part that most people miss. Everything in life is a system. I guess it nice that its underground, far away and “not in my backyard”. But it misses a point. “Getting rid of it” is not “hiding it for the time being” and burying it underground seems to be.

Why aren’t we figuring out a way to convert the CO2 back to oxygen?

I’ve heard of studies (not sure the validity) that the quantity of oxygen thousands (10’s of thousands?) of years ago was higher. I think (though can’t confirm), that we’d all feel better if we had more oxygen in the atmosphere. Why aren’t we converting the CO2 back to oxygen and releasing it back into our ecosystem? Isn’t that a better situation, and not removing little by little the resource (the oxygen) that has been in our ecosystem for thousands (hundreds of thousands?) of years?