Correlation between CO2 and Temperature
Patrick Moore posted a chart on social media that he states shows that there is no correlation between CO2 and temperature.
The chart is based on a rather bizarre variable, which is presumably one chosen by the CO2 Coalition - or somebody else - to misrepresent the known data.
On this page I will show how this trickery has been put together.
The CO2 Coalition chart
The chart on the right shows his plot of a temperature related entity to CO2.
The entity is "% of days above 100F". Why? That means we're looking at "outliers" to assess the relationship between two continuous variables. From a statistical viewpoint that is a bizarre thing to do.
The valid way to assess such a relationship is to actually plot Temperature against CO2.
Three other elements of the "analysis" also need to be dealt with in a valid way.
Firstly, we only have reliably recorded CO2 values back to 1959. Earlier values have been deduced using ice core data, so I will split the analysis into 2 charts, reflecting the difference in how the data were obtained.
Secondly, when it comes to correlation, whilst a careful choice of vertical scales can be used to hide high (or even low) correlation this is only a visual effect. Calculation of the level of correlation is independent of the scales used in a graphical represenation. So I'll use vertical scales that reflect the relationship inferred by the data, not that try to hide the relationship.
Thirdly, some of the data only relate to the United States. Clearly any analysis needs to be consistent in geographical scope.
Global average temperature vs CO2 1959-2023
Annual average global temperature anomaly values were obtained from Our World in Data.
Atmospheric CO2 values were obtained from NASA.
Plotting these produces the chart shown.
The coefficient of correlation over the period 1959-2023 is over 96%.
No correlation?
Really, Patrick?
Global average temperature vs CO2 1880-2023 (using ice core data)
Annual average global temperature anomaly values were obtained from Our World in Data.
CO2 values were obtained from NASA.
Plotting these produces the chart shown.
The coefficient of correlation over the period 1880-2023 is over 95%.
No correlation?
Really, Patrick?
Correlation is not causation
Establishing correlation does not - of course - prove causation. However, my aim here was to show that there is correlation, in direct contradiction of the strange analysis presented by Patrick Moore.
On the subject of causation, however, this is an interesting paper.