I had a similar conversation with a global warming sceptic friend.
It turns out that the "more CO2 = more warmer" model is hilariously simplified, and the real modelling gets into the weeds to put it mildly! There's a NASA database of the super-high-resolution absorption and emission spectra of every isotopic combination of every common molecule and ions, excited states, and more! It turns out that most of the forcing is determined by the behaviour of the upper atmosphere at high latitudes where the air is so thin that exotic excited states can persist for appreciable durations, and are made in large amounts by absorption of UV light. The "glancing angle" of the sunlight near the poles also means that even minor constituents participate in the exchange of IR radiation. Then, then, the simulation has to be run in many thin slices because air is so opaque to IR radiation that it bounces many times on the way up and down, and of course, the isotopic mixes (and excited fractions) are inconsistent between layers.
An insanely complex supercomputer model is required to come up with even a rough estimate of the actual warming.
And it's a huge distraction. Afaik (and I'm no climate researcher), the increased albedo of greater cloud coverage due to greater vaporization because of higher temperatures is the only known negative feedback effect. Everything else, be it reduced albedo due to less ice cover, increased release of Methane due to melting permafrost, increased release of CO2 due to more forest fires, etc. only accelerates global warming. So "more CO2 = more warmer" might be hilariously simplified, but it ain't wrong.
Only those who try to maximize profits while skirting the risk of a revolt care whether global average temperature will be 1.2 or 1.8K above pre-industrial average in ten years. For the rest it's already too warm, the damage is already plainly visible.
We don't need better models to predict future warming; we dragged our feet long enough that we can now look at historic data to see where it's going.