Guest Post by Werner Brozek Edited by Just The Facts:
To make this discussion easy, I will make the following assumptions. Dr. McKitrick’s data went until April, 2014, however I will assume his data continued to October, 2014. I will assume the lower error bar is zero for exactly 26 years in the past. I will also assume the line since September 1996 is also exactly 0 as per the following from Nick Stokes’ site:
Temperature Anomaly trend:
Sep 1996 to Oct 2014
CI from -1.106 to 1.106
First of all, I will discuss Lord Monckton’s slope of zero for a time that is slightly larger than 18 years. Lord Monckton says the slope is zero for slightly longer than 18 years as is shown by the flat turquoise line above that starts in September 1996. Another way of saying this is that when we include error bars, there is a 50% chance that cooling occurred during this time and there is a 50% chance that warming occurred during this time.
According to my interpretation of the numbers from Nick Stokes’ site, there is a 95% chance that the real slope for this period of over 18 years is +/- 1.106 degrees C/Century. The two sloping lines from September 1996 show this range. This implies there is a very small chance there is cooling of more than 1.106 C/Century. At the same time, there is the same small chance of warming at more than 1.106 C/Century.
Before I discuss Dr. McKitrick’s 26 years, I would like to offer this quote from Peterson et al., 2009: State of the Climate in 2008, American Meteorological Society Bulletin.
”The simulations rule out (at the 95% level) zero trends for intervals of 15 yr or more, suggesting that an observed absence of warming of this duration is needed to create a discrepancy with the expected present-day warming rate.”
From the above, it appears that climate scientists do not attach a huge amount of importance to the time for a slope of zero, but rather to the time that the warming is not statistically significant at the 95% level.
What Dr. McKitrick has found is that for RSS, the warming is not statistically significant at the 95% level for 26 years. So if WoodForTrees.org (WFT) gives a warming rate of X C/year, the error bars are also +/- X C/year.
According to WFT, there is warming from 26 years ago at the rate of 0.0123944 C/year. So this means that we can be 95% sure the real warming rate is 0.0123944 C/year +/- 0.0123944 C/year. Doing the adding and subtracting, this gives, at the 95% level, a range of between 0.0247888 C/year (or 0.025 C/year to two significant digits) and zero. These two ranges are indicated on the graph above starting at November 1988. Since the lower number is zero and therefore not positive, it is reasonable to say the warming since November 1988 is not statistically significant, at least according to RSS.
Analogous to the case with no warming, there is a small chance that the warming over 26 years is larger than 0.025 C/year. However there is the same small chance that there has been cooling over the last 26 years according to Dr. McKitrick’s calculations using the RSS data.
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 2014 to date compares with 2013 and the warmest years and months on record so far. 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. 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. Note that WFT has not updated Hadcrut4 since July and it is only Hadcrut4.2 that is shown.
3. For Hadsst3, the slope is not flat for any period that is worth mentioning.
4. For UAH, the slope is flat since January 2005 or 9 years, 10 months. (goes to October using version 5.5)
5. For RSS, the slope is flat since October 1, 1996 or 18 years, 1 month (goes to October 31).
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 <a href=”http://moyhu.blogspot.com.au/p/temperature-trend-viewer.html”. 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 almost 22 years according to Nick’s criteria. Cl stands for the confidence limits at the 95% level.
Dr. Ross McKitrick has also commented on these parts and has slightly different numbers for the three data sets that he analyzed. I will also give his times.
The details for several sets are below.
For UAH: Since June 1996: CI from -0.037 to 2.244
(Dr. McKitrick says the warming is not significant for 16 years on UAH.)
For RSS: Since December 1992: CI from -0.018 to 1.774
(Dr. McKitrick says the warming is not significant for 26 years on RSS.)
For Hadcrut4.3: Since April 1997: CI from -0.010 to 1.154
(Dr. McKitrick said the warming was not significant for 19 years on Hadcrut4.2 going to April. Hadcrut4.3 would be slightly shorter however I do not know what difference it would make to the nearest year.)
For Hadsst3: Since December 1994: CI from -0.007 to 1.723
For GISS: Since February 2000: CI from -0.043 to 1.336
Note that all of the above times, regardless of the source, with the exception of GISS are larger than 15 years which NOAA deemed necessary to “create a discrepancy with the expected present-day warming rate”.
This section shows data about 2014 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. 13ra: This is the final ranking for 2013 on each data set.
2. 13a: Here I give the average anomaly for 2013.
3. year: This indicates the warmest year on record so far for that particular data set. Note that two of the data sets have 2010 as the warmest year and three have 1998 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. Note that this does not yet include records set so far in 2014 such as Hadsst3 in June, etc.
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. McK: These are Dr. Ross McKitrick’s number of years for three of the data sets.
11. Jan: This is the January 2014 anomaly for that particular data set.
12. Feb: This is the February 2014 anomaly for that particular data set, etc.
21. ave: This is the average anomaly of all months to date taken by adding all numbers and dividing by the number of months.
22. rnk: This is the rank that each particular data set would have if the anomaly above were to remain that way for the rest of the year. It may not, but think of it as an update 50 minutes into a game. Due to different base periods, the rank is more meaningful than the average anomaly.
If you wish to verify all of the latest anomalies, go to the following:
For UAH, version 5.5 was used since that is what WFT uses.
For Hadsst3, see: http://www.cru.uea.ac.uk/cru/data/temperature/HadSST3-gl.dat
For GISS, see:
To see all points since January 2014 in the form of a graph, see the WFT graph below. Note that Hadcrut4 is the old version that has been discontinued. WFT does not show Hadcrut4.3 yet.
As you can see, all lines have been offset so they all start at the same place in January 2014. This makes it easy to compare January 2014 with the latest anomaly.
In this part, we are summarizing data for each set separately.
The slope is flat since October 1, 1996 or 18 years, 1 month. (goes to October 31)
For RSS: There is no statistically significant warming since December 1992: CI from -0.018 to 1.774.
The RSS average anomaly so far for 2014 is 0.254. This would rank it as 7th place if it stayed this way. 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 2013 was 0.218 and it is ranked 10th.
The slope is flat since January 2005 or 9 years, 10 months. (goes to October using version 5.5 according to WFT)
For UAH: There is no statistically significant warming since June 1996: CI from -0.037 to 2.244. (This is using version 5.6 according to Nick’s program.)
The UAH average anomaly so far for 2014 is 0.201. This would rank it as 7th place if it stayed this way. 1998 was the warmest at 0.419. The highest ever monthly anomaly was in April of 1998 when it reached 0.662. The anomaly in 2013 was 0.197 and it is ranked 7th.
The slope is not flat for any period that is worth mentioning.
For Hadcrut4: There is no statistically significant warming since April 1997: CI from -0.010 to 1.154.
The Hadcrut4 average anomaly so far for 2014 is 0.565. This would rank it as 1st place if it stayed this way. 2010 was the warmest at 0.555. The highest ever monthly anomaly was in January of 2007 when it reached 0.835. The anomaly in 2013 was 0.492 and it is ranked 9th.
For HADSST3, the slope is not flat for any period that is worth mentioning. For HADSST3: There is no statistically significant warming since December 1994: CI from -0.007 to 1.723. The HADSST3 average anomaly so far for 2014 is 0.482. A new record is guaranteed. 1998 was the warmest at 0.416 prior to 2014. The highest ever monthly anomaly was in July of 1998 when it reached 0.526. This is also prior to 2014. The anomaly in 2013 was 0.376 and it is ranked 6th.
The slope is not flat for any period that is worth mentioning.
For GISS: There is no statistically significant warming since February 2000: CI from -0.043 to 1.336.
The GISS average anomaly so far for 2014 is 0.66(4). This would rank it as first place if it stayed this way. 2010 was the warmest previously at 0.66(1). The highest ever monthly anomaly was in January of 2007 when it reached 0.92. The anomaly in 2013 was 0.59 and it is ranked 7th.
There are different ways of deciding whether or not we are in a pause. We could say that if we have a flat slope for X number of years, we are in a pause. Or we could say that if the warming is not statistically significant for over 15 years, we are in a pause. Or we could say that as long as the satellite data sets do not break the 1998 record, we are still in a pause.
In my opinion, a combination of UAH and RSS needs to show statistically significant warming for less than 15 years before I am comfortable with declaring the pause over. What do you think?