Well, if you throw the word 'meaningless' around freely without saying why you feel free to use it, you are playing propaganda games.
As Mike says, no one is arguing the CO2 aspect of the model. One can measure the amount of CO2, and one knows it does, how it might be inserted into the atmosphere, and how it might be removed. Similarly, one can count sunspots, measure solar radiation against sunspots, and watch temperatures rise and fall with sunspots. One can also measure sulfur dioxide and methane in the atmosphere. One can watch Earth's orbit change with the Milankovitch equations, and see that reflected in the historic record. One can measure the amount of soot in the air, see how soot and jet con trails cause cloud formation, and calculate how much energy gets reflected back into space by clouds. One can even dig into the old ice cores, and see where changes in the levels of this gas cause that much temperature variation and observe how many species die off.
The computer models are just an attempt to do all that at once. Any one of the above factors might be understood reasonably at a layman's level. More energy from the sun, it gets warmer. More light reflected back into space, it gets colder. The Earth moves closer to the sun, it gets warmer. Etc... Creating an algorithm, an equation that describes any one of the many factors involved, is not meaningless or mysterious. You just have to balance the effects of one influence against all the others. I'll accept your logic that curve tweaking algorithms can fit the curves automatically and objectively, given that one has a reasonable term in one's equation which reflects each physically real phenomena.
Now, I don't see algorithms (Al Gore Rhythms?) being added to the models without a meaningful theory and measurement to support them. To insert new equations, you have to insert new theory. For example, the curve fit is poor from 1950 through 1970. There is a period of cooling that isn't well explained. Well, as Mike spelled out, they have been looking into CO2 levels for decades. Global dimming, the study of man made cloud formations, is fairly new. It has only been since about 2000 that they started looking into that one. So, you have to look at your ice cores again. How many particles were in the air in any given year? How many planes were flying at what altitudes, releasing how much energy into their exhaust? You design your algorithm to fit some real physical mechanism that can be observed in nature and reproduced in the laboratory. You don't add algorithms to the models, with their new constants to tweak, until you can defend them as meaningful.
Unless you are propagandizing. Unless you are trying to modify scientific research or dismiss the results based on motivations from outside science.
Anyway, I disagree with your free use of the word 'meaningless.' Give me a reason to suppose that the models are meaningless. I also disagree with the general proposition that global warming is religion or dogma rather than science. In this exchange, as in the general discussion to the public, the warming advocates are pointing at output from reviewed journalists, while the skeptics are presenting emotion and disinformation. Calling scientific work 'meaningless' without backing it up, and asserting one is not going to believe without giving a logical account as to why, is from my perspective closer to religious thinking, an emotion and faith based adherence to old values.
People do cling to old values. People do not like to change. That isn't weather theory, but turning theory. The establishment, the group who has wealth and power under the old system, who have a vested interest in the old system, is apt to refuse to see problems that are going to force changes in the crisis. That trend is as consistent as increased CO2 levels or sunspot activity leading to warming. When I see people closing their eyes and standing rigidly still when Truth is coming on like a slow moving steam roller, I am not surprised. That's what I am seeing here.