"Focusing on the most recent hiatus below, both visually and in a 1st order linear regression analysis there clearly is effectively zero correlation between CO2 levels and global mean temperature."Unfortunately for Wolfe, all he's produced is a fine example of mathturbation as well as an example of forming a conclusion first then warping the evidence to fit.
What Wolfe did was cross-correlate GISS land temperature data and Mauna Loa CO2 records, with two vertical lines dividing the plot into three sections. The first section is marked "~18 years", the middle is marked "~21 years", and the last section is marked "~17 years".
|Figure 1. Danle Wolfe's plot from WUWT|
|Figure 2. Temperatures vs CO2 with loess trend line.|
The next deception in his graph? He failed to remove the annual cycle from both the temperature record and the CO2 record before cross-correlating them.
|Figure 3. Seasonal cycles in both CO2 records and GISS temperatures.|
|Figure 4. Scatterplots of CO2 versus temperatures, both with and without seasonal cycles removed.|
|Figure 5. Ten- versus twelve-month moving averages. Note that the seasonal cycle is still apparent in the 10-month moving average whereas it is fully removed in the 12-month moving average.|
What difference does factoring out the seasonal cycle and non-CO2 influences like El Niño/Southern Oscillation, sulfur aerosols, and solar output make on the correlation between CO2 and global temperatures? Quite a bit.
|Figure 6. Adjusted GISS temperatures versus CO2 with annual cycles removed.|
And just for Wolfe: Beyond fudging your second vertical line and "forgetting" to account for seasonal cycles and climate influences like ENSO, solar output, and sulfur aerosols, you also forgot to account for autocorrelation when you did your regression since 1999. Hint: There's a world of difference between a white noise model and an ARMA(2,1) model, especially after you take out the seasonal cycle, ENSO, aerosols, and changes in the solar cycle. In "statistician speak," you only got the results you did because of your sloppy, invalid "analysis."
Generalized least squares fit by REML
Figure 7. Adjusted GISS vs CO2 since 1999 after seasonal cycles are removed
Model: GISS ~ CO2
Subset: Time >= 1999
AIC BIC logLik
-1311.377 -1292.253 661.6886
Correlation Structure: ARMA(2,1)
Phi1 Phi2 Theta1
1.3709034 -0.4152224 0.9999937
Value Std.Error t-value p-value
(Intercept) -1.9335047 0.6987245 -2.767192 0.0062
CO2 0.0058194 0.0018289 3.181950 0.0017
Min Q1 Med Q3 Max
-1.54739247 -0.69113533 -0.06509602 0.78913695 1.69592575
Residual standard error: 0.05121744
Degrees of freedom: 181 total; 179 residual