Computer modeling has been used in industry and science since computers were able to be more than complex adding machines. Modeling is an enormously powerful tool. It allows architects and engineers to test their designs before they build them, keeping costs in control and keeping safety and reliability high.
To achieve a sound model the project must be approached without prejudice. Someone has to write a computer program to achieve an accurate simulation of a future reality. That person must not have "a dog in that fight". If the programmer has a desire for specific results, that may show up in the software design. If the programmer has a financial stake, it is almost certain to affect the coding.
When an engineer uses modeling to, for example, design a steel support structure for a building or a machine, the math involved is established and verifiable. It is the type of math taught in "Strength and Materials 101" class in every engineering school in the world.
Also, every conceivable factor must be included in the model. If the program is to analyze the structure of a proposed skyscraper all external factors such as the wind, it's direction and speed, the makeup of the land on which the building will sit, floor loading, and hundreds of other factors must be brought into the code. There is no room for guesswork.
Which brings us to "global warming" or "climate change" or "global chaos" or what ever name is currently popular with those trying to sell a flawed product. There is no way that we can even know of all of the factors that go into the climate of this planet. It is far too complex. The math to analyze climate might allow meteorologists to tell you to bring your umbrella to work tomorrow. Often they are right on that. But to predict the climate of our whole Earth for years in the future? That just cannot be done.
The other thing is, that those that are touting this, do have "a dog in the fight". A very large financial dog. After all it has made a failed presidential candidate a much richer man then he was before he started selling "snake oil". But this whole thing started in the halls of academe in Great Britain at the University of East Anglia. When things like this come from a University, it is generally because some Phd is looking for a grant. So, as usual, here comes a financial angle.
But, it seems, that the press and other "Chicken Little" imitators have bought into this completely. I suspect, because it supports the liberal, "man is evil and destroying the planet", rant. There are those who accept these things as absolute truth, never checking the facts. Well here are just a few facts.
The average world temperature hasn't increased in eighteen years.
There are more trees in North America than there were when Columbus landed.
There are more deer and turkey in the United States than when Columbus landed.
If there were a slight increase in temperature it would allow longer growing seasons.
The Connecticut river, which was an open sewer fifty years ago, is now a Class A river.
They now catch lobster in Boston Harbor.
The Polar Bear population is at a record high.
I am sure there are many more examples. Those are just a few that I am aware of. So maybe we are not doing such a terrible job after all in the US. So go beat on China and India. See if they will clean up their act.