Note: Graphs and texts in italics are from the Cato Working Paper No. 35.
Now I am going to compare Michaels and Knappenberger’s historical findings in their Cato Working Paper No. 35 with the 2017 NASA-GISS observational data graph I found at Robert Fanney’s blog “Robertscribbler,” presented below. You will be able to find it at the NASA website, located here (click on "Global Annual Mean Surface Air Temperature Change").
Chart A: The black squares are the annual global mean average estimated temperatures since 1880. Obviously NASA didn’t exist all the way back to 1880 so the older averages were computed from data that were taken from various sources such as the US and British Imperial weather services. The red line represents the “Lowess Smoothing,” I haven’t the faintest clue what that means. The Blue I’s represent uncertainty bars: 0.25 C spread (+/- 12.5 C) in the late 19th Century (1892), 0.17 C spread in the mid-Twentieth (1948) and 0.10 C spread in the late 20th / early 21st Centuries (2009). The 2017 global mean temperature (not shown) is estimated to be approximately 0.92 deg C above the 20th Century average.
This graph shows a cooling from 1880 to 1909, the a slight warming ‘til about 1945, another slight cooling until 1976 ad then a consistent rise at roughly 0.2 deg C per decade through 2016. There is a low point at 1992, the year after Mount Pinatubo blew up. The 2002-2014 Pause is hidden in the annual means’ noise but the Lowess Smoothing detects a shorter pause or at the very least a massive deceleration.
Well we can use these temperatures to check Michaels and Knappenberger’s plot of the NASA GISS temperature data and I’ve done so by printing the above on an 8½ by 11, drawing gridlines straight across and scaling to the nearest millimeter (half-millimeter if the square falls right between two lines) to the nearest gridline. The temperatures are plotted not in 10th of a degree Celsius, but in hundredths of a degree. So I scaled off from -0.5 to +1.0 and came up with a scale converter. I did the same thing from Cato’s Figure 2 for the GISS multiyear trends, plugged everything into an Excel spreadsheet, used the LINEST command to construct a trend, and down below are the plots.
Chart B: The red line is the plot line of the multiyear decadal trends I generated for the reference year 2015 from the 2017 NASA GISS temperature records graph downloaded Sunday, October 01, 2017. The blue line represents the plot line of the multiyear decadal trends. Note the red line is noticeably forward a year beginning about the trend length of 40 years. Otherwise it is in reasonable close conformity to my red line graph.
My plot shows the jump in trend from the 11-year trend length to the 10-year trend length. This is the first year that the signal from 2015 has made itself known to a much higher amplitude within the trends. All subsequent years with their shorter trend lengths are probably excessively noisy.
Michaels and Knappenberger’s plot has that one year deviation that I had noticed before, starting at about the 40-year trend length—it is ahead of my plot by exactly one year. This is a fat-fingered error: either in the authors’ Figure 2 graph, or in the stated year runs in its caption. The global cooling from Mount Pinatubo was removed from 1992 to 1993! Any way let the record show that the NASA GISS 2006-2015 trend increased from the authors’ value of 0.12 deg C per decade to the true value of almost 0.20. With errors such as these and the others noted in Part 1, errors that I, a layman have discovered, it really doesn’t inspire any confidence in me that they are doing rigorous enough science---hard science---for it to pass peer review or auditing!
Now we are going to check the proper plotline against the IPCC’s CMIP-5 forecast, as shown in the Cato paper. The multiple model runs were based on historical data up to 2006 and the RCP4.5 scenario after that year.
Chart C: Cato’s CMIP5 model and NASA GISS 2015 data set runs showing trends from 1951 through 2006 with reference year to 2015, with my NASA GISS 2017 data set runs for and referenced to the same years. The purple line is the multiple model-run mean, the cyan and spring green lines are the model-runs’ 97.5% and 2.5% percentiles respectively. The blue line is Cato’s trend plot from the 2015 NASA GISS data set and the red line is my trend plot from the 2017 NASA GISS data set.
Again, this graph shows that the one-year discrepancy that I had noticed in Figure 2 (Part 1) is proven. The peaks in the trends as computed by Michaels and Knappenberger are in the 23-years’ trend length (1993-2015), instead of the 24-years’ length (1992-2015) as my NASA GISS plot (red line) shows and is reflective of the actual global mean temperature low point in 1992 (see Chart A). The authors’ GISS plot shows a continued low warming trend of about 0.12 deg C per decade whereas mine increases to 0.200 deg C per decade and close to the multiple model-run mean (MMM).
Now to find out the source of the Cato paper’s discrepancy I took their plotted NASA GISS values from Figure 2, and compared them to my computed trends for the NASA GISS temperature records from 1950 through 2005 and referenced to 2014. When I made a plot, my numbers and the paper’s numbers became widely variant when running into the shorter trend lengths, so I won’t belabor the point here.
So then what I did was reset their end years, 1951 and 2006, to 1950 and 2005 respectively, and kept my plot the same as it was in Chart B, with an added year 1950 and the 2006 year dropped. The referenced year remained the same throughout: 2015. And this is what I found in Chart D below:
Chart D: The Cato paper’s CMIP5 model and NASA GISS 2017 data set runs showing trends reset to beginning in 1950 and ending in 2005 with reference year to 2015, with my NASA GISS 2017 data set runs for and referenced to the same years. “Annual years” are the years for the starting points of the respective trends. End points for all trends is 2015. The trend lengths now vary from 66 years (1950-2015) to 11 years (2005-2015). Explication of colored lines are the same as in Chart C.
This adjustment achieves a much better fit for the Cato paper’s model runs and GISS data set plot lines. The peak trends resulting from the 1992 global mean temperature low point are now where they should be. The Cato NASA GISS trend plot (blue line) and mine (red line) are now in close conformity to each other up to the trend length of 13 years and only diverge after that. This is probably because Michaels and Knappenberger came up with an estimate for the year 2015:
We have also updated our AGU presentation [in December 2014] with our best guess for 2015 average temperatures.
The actual NASA GISS global mean average temperature for 2015 was apparently higher than the authors’ estimate, and the other actual data sets would probably show higher 2015 averages as well. The gross errors that were introduced in Figure 2 (Part 1) and the discrepancies between Figures 2 and 3 are probably due to the author’s stated updating without checking to make sure that their trend lengths in the graph and stated run years in Figure 2’s caption were correct, as they are not.
Now on to checking Cato’s Figure 3.
Chart E: The Cato paper’s CMIP5 modified model set and the 2014 Hadley HadCRUT4 data set (blue line) compared with the 2017 NASA GISS data set (red line) for all trends with end year reference of 2014. Trend lengths begin with 65 years (1950-2014) and end with 10 years (2010-2014). The Model set has been modified according to the Hadley HadCRUT4 Method to reflect a blend of land surface air temperatures and sea surface temperatures, and obtained from the University of York website (http://www-users.york.ac.uk/~kdc3/papers/robust2015/index.html). Explication of the model set’s colored lines are similar to those in Charts C & D.
In the above Chart, the NASA GISS trend plot line roughly parallels the HadCRUT4 line until about the 45-years’ trend length, then follows in close conformity thereto until the 27-years’ trend length, whereupon the two lines diverge. Both lines hit a peak at the 23 years’ (1992-2014) trend length—right after Mt. Pinatubo blew up, after which they slowly descend roughly parallel to each other until they hit a low point at 2005. This descent is indicative of a steadily but noisily increasing mean of global temperature until 2002, where it levels off, going into the Pause which ended in 2014. The parallel descent into very low decadal trends indicates that Michaels and Knappenberger had referenced their Hadley data set trends in their Figure 3 for the end year of 2014, and is not indicative of fat-fingered errors at the Cato institute. It also means that Figure 3 is, essentially, correct.
I am unable to check Figure 4 owing to the fact that Christy’s data in Figure 1 went by annual five-year global mean temperatures and his corresponding data in Figure 4 went by annual means as indicated in the two figures and their captions. So I will compare the model forecasts with the observed temperatures in Figure 1 instead.
Chart F. The Cato paper’s CMIP5 Model set for the tropical mid-troposphere compared with the 2015 Christy balloon data sets (red line) for all trends with end year reference of 2015. Trend lengths begin with 40 years (1976-2015) and end with 10 years (2006-2015). The temperature data from the Model set and the balloon data sets have been provided to the Cato Institute by Dr. John Christy of the University of Alabama in Huntsville.
The results are similar to what is seen in Cato’s Figure 4. The data from Dr. Christy comport with the Figure 4 trends that run significantly lower than the mean of the multiple model runs (MMM) and even below the 2.5th percentile line. The plot line shown here also runs below the minimum for all runs from the 33-year to 23-year trend lengths. The plot line also confirms the sense of Figure 4 in that the trends are running almost uniformly at 0.1 deg C per decade. A caution noted here is that Christy’s observational data are from the five-year running averages shown in Figure 1, so some noise has been eliminated from the data. A comparison of this graph with Charts C and D shows that through 2015, when the trends end outside the Pause, the tropical mid-troposphere appears to be warming at a slower rate than is the surface, possibly giving a greater differential between surface and mid-troposphere temperatures and thereby allowing for more moisture-laden air to arise from our lands and seas to supercharge our weather, although a caveat should be noted that the tropical mid-troposphere temperatures should be compared with the tropical surface temperatures and that temperatures at altitude are expected to warm much less than the surface at higher latitudes.
Conclusion on Checking Cato’s Figures.
Although Michaels and Knappenberger’s Figures 1, 2 and 3 appear to be correct, and their discussion is for the almost the whole very well written, I cannot recommend this paper to anyone without serious reservations because of the gross errors they introduced into Figure 2 when they updated it for release of the paper at the end of 2015. It would have been better they left the plot lines remaining as they were in 2014, as they did for their Figure 3. They have also failed to do another check, which is to compile uniform multiple-year trends, for example, 30-year trends going back from 1985-2014 to 1921-1950.
Well I’m up to 2,000 words now. I will leave it for Part 3 to see if this paper has held up under the increased temperatures of 2016 and 2017.