"does not mean that nobody understands what's going on."
What are all the inputs and outputs? Which are significant? Does anybody know the answer to either of these questions? You can build a model without knowing all the inputs and outputs, but it's called a guess.
For the global temperature, the input is ~99.98% light and a tiny amount of heat from the earth’s core etc, and the output is light to space. The earth receives ~174 petawatts 24/7 365 and you can't really hide energy on that scale for very long. (http://en.wikipedia.org/wiki/Earths_energy_budget) You can directly measure this stuff so it's not really a guess.
PS: He used "tera-watt scale" which is about as true as saying watt scale. Well he was only off by 1000x so it's not quite that bad.
What are all the inputs and outputs? Which are significant? Does anybody know the answer to either of these questions? You can build a model without knowing all the inputs and outputs, but it's called a guess.