Yes, the averages can and do change—that is my point. A changing average suggests something about the system is changing. It doesn’t need to be compared to prei

Yes, the averages can and do change—that is my point. A changing average suggests something about the system is changing. It doesn’t need to be compared to preindustrial temperatures, but it is a good baseline because the temperature variation (as shown in the chart) was pretty small within that timeframe compared to the changes we are seeing today.