One way scientists test their predictive (e.g. Climate Change) models is to use past data to predict the present situation. If you have climate data going back, say 100 years, you can plug it into the model and see how well it predicts the climate now. If the results look good, this increases your confidence in the model’s prediction for the next 10 to 20 years. Like Science itself, Climate Change models are evolving and making better, more accurate predictions.
The final way we test our models is in the marketplace of ideas. If the overwhelming majority of the expert scientific community are convinced of the validity of a particular model, then it is likely our decision makers will also be persuaded. But this is not always the case; sometimes politics trumps logic. But just as we all hope that Good will eventually triumph over Evil, I continue to hope that reason will rise above politics and that the good work of scientists worldwide will preserve our planet and our species. As the TV pundits say, “Only time will tell.”