The data you referenced also mentions 2,000 ppm for CO2 as a maximum that has not been exceeded in the historical data.

In the last 500my it hasn't gone above 2,000ppm. Since LIFE evolved.

It was probably higher in the early stages of the Earth's formation and initial 'out-gassing'. However, tectonic activity constantly exposes/creates new rock on the surface.

On a "geologic scale" CO2 levels decline due to CO2 being pulled from the atmosphere by exposure to aging rocks. It's a fairly SLOW process most of the time.

Perhaps there are additional feedback loops that kick in once the bomb explosion in heating peaks out that work to cool the planet from its heat maximum.

There are 'cooling feedbacks' that will lead to a RAPID "cool down" of the Earth once our Carbon Bomb begins to dissipate. Unfortunately, that probably won't be for about 2-5 thousand years.

I have been trying find a way to "visualize" what's going to happen to the Climate System. The best I can think of is the way they put out fires on spaceships in the movies.

They open an airlock, and all the air carrying the HEAT/FIRE rushes out in a sort of burning stream of hot plasma.

Now, think of the Poles as the "airlocks" of the planet. The MASSIVE thermal pulse from our Carbon Bomb is RUSHING towards them in a slow moving "blast wave" that will become a "plasma jet" of HEAT at each Pole.

That's how the "Planetary Emergency Cooling System" works. It's how the Earth sheds excess HEAT.

As soon as CO2 levels fall, and the flow of HEAT from the Equator drops off, the "plasma jet" will collapse. That's when the RAPID COOLING will begin.