"Modelers generally agree that the climate system is a chaotic system in both a technical and practical sense, rendering short-term weather patterns unpredictable beyond a few weeks." (pg 899)
How true that is.
Since the venerable
Dick Goddard can't even tell me if it'll be 10F or 60F next week, I'm inclined to ignore anyone who says, "Based on my sophisticated computational model, the 2027 global climate will be [insert stupid opinion here]
."
Even the simplest weather models are chaotic - i.e. extremely sensitive to initial conditions. No dungeon master worth his twenty-sided die believes the outcome of this roll can be predicted.
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Heat is a different story, though. Heat ("q" from thermo) can only added to the planet from a) cosmic (specifically Solar) radiation, and b) terrestrial release (e.g. burning the Cretaceous period). q can only be shed by radiation.
Atmospheric [CO2] decreases q radiation losses. Since solar q intake has been relatively stable, terrestrial q release has been increasing, and atmospheric [CO2] has been increasing, it doesn't take a rocket scientist to realize total planetary q is increasing.
The effect of that increased q is (obviously) quite debatable, however.