To see the usual arguments for global warming, look no further than this list, which gives the most popular "skeptic arguments" with rebuttals. The person who made this list presumably read lots of stuff and tried to select the best rebuttal in every case.
That reading led to this:
Skeptic argument: Models are unreliable.
Rebuttal: Models successfully reproduce temperatures since 1900 globally, by land, in the air and the ocean.
Notice what it doesn't say. It doesn't say Models have successfully predicted temperatures . . .
These models have many adjustable parameters. With enough adjustable parameters, you can reproduce anything. The only reasonable test of a model with many adjustable parameters is how well it predicts.
Hal Pashler and I wrote a paper pointing out that psychologists had been doing something similar for 50 years - passing off models with many adjustable parameters as reliable when in fact they hadn't been tested - when their ability to predict hadn't been measured. One explanation of the current global warming scare is that there is something to be afraid of. A more plausible explanation, I believe, is that - again - one group of scientists is passing off complex models with many adjustable parameters as reliable when in fact they haven't been tested.