This is not a rebuttal to the parent. They’re talking about stability of prediction of aggregate properties, and you’re fixating on numerical precision errors a

This is not a rebuttal to the parent. They’re talking about stability of prediction of aggregate properties, and you’re fixating on numerical precision errors and algorithm bugs in particular implementations. The one has little to do with the other. Numerical instability leads to obvious, wildly inconsistent errors. It isn’t subtle. Literally no climate simulations are going off the rails because of these kinds of first-year grad-student code problems.