It does not matter how high the CO2 concentration goes, upon stopping the burning of fossil fuels (which must eventually happen as fossil fuels are a non-renewable resource), it will eventually go back down. The question is how high the concentration will go and how much of an impact that will have on the Earth's temperature.
Thus far, all of the CO2 we have placed into the atmosphere has at least partially and likely mostly has led to the 0.8 degree increase we have seen.
Previously, we were in a interglacial period, with the climate in the temperate zone swinging gently from point A to point B and then back to point A. But, with global warming, the climate appears to have swung past point B, which has never happened before during the interglacial period, that is, the climate period that we have been in for, perhaps, millions of years. Nobody can tell what will happen now.
While there is no going back, certainly with our current understanding and technology. It's not the end of the world. There are things we can do to manage the impact and avoid it being catastrophic.
Unfortunately the obstacles seems to be political more than anything. Which is never good
Pretty much. CO2 stay up for hundreds of years and we have not yet seen the full effect of what we have already put up in the air. It is very expensive, if at all possible, to remove much.
