No it couldn't. DSGE models are not based on fundamental physical laws.
Of course they are based on fundamental physical laws. Every physical process in the universe obeys the Laws of Thermodynamics--economics is no different to climate science in this respect. What we are talking about in both cases is modelling the
behaviour of highly complex dynamic systems.
For instance, the climate contains many coupled oscillating subsystems, like the ENSOs, the Pacific Decadal Oscillation (PDO, discovered twelve years ago), the North Atlantic Oscillation, etc, etc. The climate also includes atmospheric winds, the atmosphere itself, and on and on, and all these subsystems are exchanging energy between themselves, between themselves and the sea, the ice caps, changing the temperature of any of the systems without any external cause. Before humans started producing CO2, the climate of the planet changed all of its own accord. Pretty crazy, huh?
My point is that you are massively overestimating the power of these models. I don’t know why that is, but you are. Look again at the IPCC’s graph.
You posted some kind of corporate brochure from these GCM guys and it says that the models are not statistical fits, they are micro and meso founded models of the climate. Sure, just like DSGE models. And, just like DSGE models, GCMs tie down parameters in their micro and meso foundations (so-called “deep parameters” in the DSGE lit) by fitting (or calibrating) to historical data or proxies thereof. Of course, these models are hugely complicated. But,
on average, all of the noise from the complex positive and negative feedback effects and dynamic mediation cancels out to give a pretty linear response to nothing more than simple greenhouse forcing, for example as described in the basic greenhouse model I gave earlier:
Global Warming = 0.36 x (33°C) x [(Total Forcing) ÷ (Base Forcing)]
Hugely complicated, yes, in principle. In practice, not so much.