Climate researchers don’t just make up models and then assume they are right. They actually compare them against the reach world.
For example, we have fairly detailed climate related data sets going back many thousands of years, coming from many different kinds of sources. You input these as starting conditions to a model, run the model forward, and then see how accurate its predictions are against later historical data.
Despite your feelings about is or is not possible, there is very strong research that shows that climate modeling works.
That you described there is not modeling, it's curve fitting. Run enough model, and one will track. It's survival bias tho, and offer very little guarantees to track the future.
For example, we have fairly detailed climate related data sets going back many thousands of years, coming from many different kinds of sources. You input these as starting conditions to a model, run the model forward, and then see how accurate its predictions are against later historical data.
Despite your feelings about is or is not possible, there is very strong research that shows that climate modeling works.