Guest Post by Werner Brozek, Edited by Just The Facts:
The above are plots of what the slopes NOAA’s surface temperature anomalies look like for the three intervals 1975 to 2000; 1950 to 2000; and 2000 to 2015. The top one is before adjustments and the bottom one is after adjustments, seemingly in an attempt to get rid of the hiatus. The given slopes are in degrees C/century.
Karl Popper said: “For it is always possible to find some way of evading falsification, for example by introducing ad hoc an auxiliary hypothesis, or by changing ad hoc a definition.”
So exactly what is the definition of a hiatus? NOAA defines a “hiatus” as a slowdown in warming and not a complete stop, so we are NOT talking about a pause with a very slight negative slope when talking about whether or not we are in fact experiencing an “hiatus”. However by talking about a “slowdown”, at least three different elements need to be defined so we can all be clear whether of not a hiatus has indeed occurred.
We need to know how long the recent period is that we are comparing things to. Then we need to know how long the previous period can be that we are using for a comparison. Then we need to know how much higher the previous period needs to be in order for us to have a hiatus. For example, does the previous slope need to be at least 10% or 20% or 30% higher than the most recent slope in order to claim that we have a hiatus?
Let me illustrate why the above are important with an analogy. Suppose Bob is born with a height of 20 inches at birth. Then Bob grows to be 5 feet when his 12th birthday is reached. Then Bob undergoes a huge growth spurt and reaches 6 feet on his 13th birthday. Then his growth rate slows down and he only gains another 4 inches by his 14th birthday. Now the question is: “Did his growth rate slow down?” Probably 97% of people would say the growth rate slowed. But 3%, all climate scientists, would say there never was a change in growth rate. They would say Bob grew 52 inches or 4 inches per year in the first 13 years. And since he grew 4 inches between ages 13 and 14, there was no slowdown. Would you agree?
If I were to define a hiatus, I would say the most recent period must be at least 15 years. And the period preceding it must also be at least 15 years, but not more than 25 years. And the slope of the preceding period must be at least 30% more than the latest slope. By this definition, even NOAA shows a hiatus since the recent ratio for 1975 to 2000 versus 2000 to 2015 is 1.717/1.143 or 1.50 so the preceding period has a slope that is 50% more than the latest slope. Would you agree? Of course, comparing 2000 to 2015 with 1950 to 2000 gives a completely different picture as can be seen on the above diagrams.
Before the revisions, the ratio for the slopes for (1950 to 2000)/(2000 to 2015) was 1.48, so the 50 year period had a slope that was 48% larger. But afterwards, the latest 15 year period actually had the larger slope. In all fairness to Thomas Karl, I am not aware of a precise definition of a hiatus so no one can accuse him of changing definitions. However I do believe it is ingenious of him to compare the recent 15 years with 50 years before that, especially since virtually nothing happened for the first 25 of those 50 years.
The following is from their report: “In summary, newly corrected and updated global surface temperature data from NOAA’s NCEI do not support the notion of a global warming ‘hiatus.’ Our new analysis now shows the trend over the period 1950-1999, a time widely agreed as having significant anthropogenic global warming (1), is 0.113°C dec−1, which is virtually indistinguishable with the trend over the period 2000-2014 (0.116°C dec−1).”
The above statement perplexes me. They appear to be satisfied that they have proven to themselves and hopefully others that no hiatus occurred. But in doing so, they have, in my mind, proven that there is no catastrophic warming occurring either. A warming rate of 1.16 C/century will not reach 2 C by 2100.
In the sections below, as in previous posts, we will present you with the latest facts. The information will be presented in three sections and an appendix. The first section will show for how long there has been no warming on some data sets. At the moment, only the satellite data have flat periods of longer than a year. The second section will show for how long there has been no statistically significant warming on several data sets. The third section will show how 2015 so far compares with 2014 and the warmest years and months on record so far. For three of the data sets, 2014 also happens to be the warmest year. The appendix will illustrate sections 1 and 2 in a different way. Graphs and a table will be used to illustrate the data.
This analysis uses the latest month for which data is available on WoodForTrees.com (WFT). All of the data on WFT is also available at the specific sources as outlined below. We start with the present date and go to the furthest month in the past where the slope is a least slightly negative on at least one calculation. So if the slope from September is 4 x 10^-4 but it is – 4 x 10^-4 from October, we give the time from October so no one can accuse us of being less than honest if we say the slope is flat from a certain month.
1. For GISS, the slope is not flat for any period that is worth mentioning.
2. For Hadcrut4, the slope is not flat for any period that is worth mentioning.
3. For Hadsst3, the slope is not flat for any period that is worth mentioning.
4. For UAH, the slope is flat since February 1997 or 18 years and 4 months. (goes to May using version 6.0)
5. For RSS, the slope is flat since December 1996 or 18 years and 6 months. (goes to May)
The next graph shows just the lines to illustrate the above. Think of it as a sideways bar graph where the lengths of the lines indicate the relative times where the slope is 0. In addition, the upward sloping blue line at the top indicates that CO2 has steadily increased over this period.
When two things are plotted as I have done, the left only shows a temperature anomaly.
The actual numbers are meaningless since the two slopes are essentially zero. No numbers are given for CO2. Some have asked that the log of the concentration of CO2 be plotted. However WFT does not give this option. The upward sloping CO2 line only shows that while CO2 has been going up over the last 18 years, the temperatures have been flat for varying periods on the two sets.
For this analysis, data was retrieved from Nick Stokes’ Trendviewer available on his website. This analysis indicates for how long there has not been statistically significant warming according to Nick’s criteria. Data go to their latest update for each set. In every case, note that the lower error bar is negative so a slope of 0 cannot be ruled out from the month indicated.
On several different data sets, there has been no statistically significant warming for between 14 and 22 years according to Nick’s criteria. Cl stands for the confidence limits at the 95% level.
The details for several sets are below.
For UAH6.0: Since October 1992: Cl from -0.026 to 1.731
This is 22 years and 8 months.
For RSS: Since January 1993: Cl from -0.013 to 1.672
This is 22 years and 5 months.
For Hadcrut4.3: Since July 2000: Cl from -0.017 to 1.371
This is 14 years and 10 months.
For Hadsst3: Since June 1995: Cl from -0.003 to 1.739
This is an even 20 years.
For GISS: Since November 2000: Cl from -0.018 to 1.336
This is 14 years and 7 months.
This section shows data about 2015 and other information in the form of a table. The table shows the five data sources along the top and other places so they should be visible at all times. The sources are UAH, RSS, Hadcrut4, Hadsst3, and GISS.
Down the column, are the following:
1. 14ra: This is the final ranking for 2014 on each data set.
2. 14a: Here I give the average anomaly for 2014.
3. year: This indicates the warmest year on record so far for that particular data set. Note that the satellite data sets have 1998 as the warmest year and the others have 2014 as the warmest year.
4. ano: This is the average of the monthly anomalies of the warmest year just above.
5. mon: This is the month where that particular data set showed the highest anomaly. The months are identified by the first three letters of the month and the last two numbers of the year.
6. ano: This is the anomaly of the month just above.
7. y/m: This is the longest period of time where the slope is not positive given in years/months. So 16/2 means that for 16 years and 2 months the slope is essentially 0. Periods of under a year are not counted and are shown as “0”.
8. sig: This the first month for which warming is not statistically significant according to Nick’s criteria. The first three letters of the month are followed by the last two numbers of the year.
9. sy/m: This is the years and months for row 8. Depending on when the update was last done, the months may be off by one month.
10. Jan: This is the January 2015 anomaly for that particular data set.
11. Feb: This is the February 2015 anomaly for that particular data set, etc.
15. ave: This is the average anomaly of all months to date taken by adding all numbers and dividing by the number of months.
16. rnk: This is the rank that each particular data set would have for 2015 without regards to error bars and assuming no changes. Think of it as an update 25 minutes into a game.
If you wish to verify all of the latest anomalies, go to the following:
For UAH, version 6.0 was used. Note that WFT uses version 5.6. So to verify the length of the pause on version 6.0, you need to use Nick’s program.
For Hadsst3, see: http://www.cru.uea.ac.uk/cru/data/temperature/HadSST3-gl.dat
For GISS, see:
To see all points since January 2015 in the form of a graph, see the WFT graph below. Note that UAH version 5.6 is shown. WFT does not show version 6.0 yet.
As you can see, all lines have been offset so they all start at the same place in January 2015. This makes it easy to compare January 2015 with the latest anomaly.
In this part, we are summarizing data for each set separately.
The slope is flat since December, 1996 or 18 years, 6 months. (goes to May)
For RSS: There is no statistically significant warming since January 1993: Cl from -0.013 to 1.672.
The RSS average anomaly so far for 2015 is 0.287. This would rank it as 6th place. 1998 was the warmest at 0.55. The highest ever monthly anomaly was in April of 1998 when it reached 0.857. The anomaly in 2014 was 0.255 and it was ranked 6th.
The slope is flat since February 1997 or 18 years and 4 months. (goes to May using version 6.0)
For UAH: There is no statistically significant warming since October 1992: Cl from -0.026 to 1.731. (This is using version 6.0 according to Nick’s program.)
The UAH average anomaly so far for 2015 is 0.179. This would rank it as 6th place. 1998 was the warmest at 0.483. The highest ever monthly anomaly was in April of 1998 when it reached 0.742. The anomaly in 2014 was 0.170 and it was ranked 6th.
The slope is not flat for any period that is worth mentioning.
For Hadcrut4: There is no statistically significant warming since July 2000: Cl from -0.017 to 1.371.
The Hadcrut4 average anomaly so far for 2015 is 0.676. This would set a new record if it stayed this way. The highest ever monthly anomaly was in January of 2007 when it reached 0.835. The anomaly in 2014 was 0.564 and this set a new record.
For Hadsst3, the slope is not flat for any period that is worth mentioning. For Hadsst3: There is no statistically significant warming since June 1995: Cl from -0.003 to 1.739.
The Hadsst3 average anomaly so far for 2015 is 0.484. This would set a new record if it stayed this way. The highest ever monthly anomaly was in August of 2014 when it reached 0.644. The anomaly in 2014 was 0.479 and this set a new record.
The slope is not flat for any period that is worth mentioning.
For GISS: There is no statistically significant warming since November 2000: Cl from -0.018 to 1.336.
The GISS average anomaly so far for 2015 is 0.77. This would set a new record if it stayed this way. The highest ever monthly anomaly was in January of 2007 when it reached 0.93. The anomaly in 2014 was 0.68 and it set a new record.
It appears as if we need to have a precise definition as to exactly what is required to officially have a hiatus. Until we do, any one can use whatever criteria they wish and declare the hiatus over, or to have never occurred, according to their definition. This is one illustration as to how much more climate science needs to mature.