You're a total ignoramus when it comes to science and the scientific method.What a person who uses and understands science would do is check the theories, the evidence and the past record for these computer models.
Checking the theories, the existing evidence and the past record of the computer models allows you to form a hypothesis. But none of that qualifies as observed data for the forecasted predictions.
The scientific method (article) | Khan Academy
How the scientific method is used to test a hypothesis.
www.khanacademy.org
The scientific method is clear: You determine whether the predictions are supported by evidence by looking at the observed results, not the computer-generated projections.
The only way to have "proof" of the outcomes in 2050 is to have gathered evidence in the year 2050.
Unless the climate researchers have travelled to the future, it is impossible for them to have proof to support to their hypothesis.
Not to mention that their range of forecasted outcomes is so enormous that it is essentially a prediction that anything could happen. It's no wonder NASA is confident in that "prediction."