A method for analyzing or optimizing the operation of waste incinerator systems. The content of CO2 is measured in the exhaust gas and is used to determine the ratio of biogenic carbon to fossil carbon in the incinerated waste, if necessary after resetting to the CO2 reference quantity. The variability of the CO2 reference or the ratio of biogenic carbon to fossil carbon in the incinerated waste is determined and recorded according to quantity and duration. When optimizing the operation, the location of the waste in the bunker, from which the incinerated waste originates with a composition or variability that has now been ascertained using the method, is used to further remove or mix the waste.