Let's say a magical enviro-fascist cabal of superhumans appears tomorrow and are somehow able to completely dismantle and ban all sources of energy that emit large amounts of CO2 while also somehow providing replacement quantities of non-emitting alternatives (e.g. wind, solar, and nuclear).

In this environment we will still need to geoengineer the planet for as long as the carbon we have already burned remains in the atmosphere. We are already way outside the pre-industrial baseline. And carbon capture is very energy-intensive, so no matter how much of our solar energy abundance we put into it, we are going to be geoengineering for decades.

If it’s only decades, we’ve been very, very lucky.