By the amount of (some of it useless) tech we've come to build in the last 3 decades, we should have arrived at the stage where we can collectively control the CO2 levels in our atmosphere, by now. For ever.
We failed.
We failed.
Cutting down on annual emissions will not be accompanied by reduction in atmospheric CO2, unless the current rate of emission is lower than that of natural processes that take CO2 out of the atmosphere.
That's why atmospheric CO2 continues to rise, despite cuts, if the cuts at global scale are at all real.
Enough cheap energy (that doesn't produce CO2) and some incentive and you could have CO2 slowly removed.
Like in Critical Mass by Daniel Suarez.
Of course the free energy would instantly allow us to eliminate a huge amount of emissions but that's not really relevant to the point. All the concrete for the tens of thousands of facilities would add up a good amount of additional CO2 to scrub as well.