Major Tom, you write “Well and good – except for that fact that all forecasts are based on models that, by definition, cannot have been validated.”
Wrong. Short term forecasts CAN be validated. We will know if in a few months whether the forecast correct. It is the long term forecasts that can only be validated when we have the actual data on which to validate them. So, if you are making a 30 year forecast, we will have to wait 30 years until we know is the forecast is valid.