Wouldn't you need data going back for thousands of years? 40 years of data won't tell you anything about the cause of the temperatures in this data set. You'l

Wouldn't you need data going back for thousands of years? 40 years of data won't tell you anything about the cause of the temperatures in this data set. You'll need to eliminate the possibility that we are in a Little Heat Wave cycle; if you got forty years of temperature data during the beginning of the Little Ice Age, you won't have a representative sample, for instance.