Compared to a spherical cow model we could make as soon as we realized that CO2 the oceans absorbed didn't stay absorbed we've only done a little better. It's

Compared to a spherical cow model we could make as soon as we realized that CO2 the oceans absorbed didn't stay absorbed we've only done a little better. It's a complicated system, we don't know all the detail, and the calibration of the older models we've been able to robustly test at least just wasn't there. Compared to constant model where the temperature stays the same both the modern sophisticated model and the spherical cow model do much, much better. For simple things like "how much infrared light and in what bands does CO2 absorb" we can measure that in a laboratory and have it nailed down.