Guest Post By Werner Brozek, Edited By Just The Facts
In order to answer the question in the title, we need to know what time period is a reasonable period to take into consideration. As well, we need to know exactly what we mean by “stalled”. For example, do we mean that the slope of the temperature-time graph must be 0 in order to be able to claim that global warming has stalled? Or do we mean that we have to be at least 95% certain that there indeed has been warming over a given period?
With regards to what a suitable time period is, NOAA says the following:
”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.”
To verify this for yourself, see page 23 of this NOAA Climate Assessment.
Below we present you with just the facts and then you can assess whether or not global warming has stalled in a significant manner. 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 several data sets. The second section will show for how long there has been no significant warming on several data sets. The third section will show how 2012 ended up in comparison to other years. The appendix will illustrate sections 1 and 2 in a different way. Graphs and tables will be used to illustrate the data.
Section 1
This analysis uses the latest month for which data is available on WoodForTrees.org (WFT). (If any data is updated after this report is sent off, I will do so in the comments for this post.) 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.
On all data sets below, the different times for a slope that is at least very slightly negative ranges from 8 years and 3 months to 16 years and 1 month:
1. For GISS, the slope is flat since May 2001 or 11 years, 7 months. (goes to November)
2. For Hadcrut3, the slope is flat since May 1997 or 15 years, 7 months. (goes to November)
3. For a combination of GISS, Hadcrut3, UAH and RSS, the slope is flat since December 2000 or an even 12 years. (goes to November)
4. For Hadcrut4, the slope is flat since November 2000 or 12 years, 2 months. (goes to December.)
5. For Hadsst2, the slope is flat since March 1997 or 15 years, 10 months. (goes to December)
6. For UAH, the slope is flat since October 2004 or 8 years, 3 months. (goes to December)
7. For RSS, the slope is flat since January 1997 or 16 years and 1 month. (goes to January) RSS is 193/204 or 94.6% of the way to Ben Santer’s 17 years.
The following graph, also used as the header for this article, 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 sloped wiggly line shows how CO2 has increased over this period:
The next graph shows the above, but this time, the actual plotted points are shown along with the slope lines and the CO2 is omitted:
Section 2
For this analysis, data was retrieved from WoodForTrees.org and the ironically named SkepticalScience.com. This analysis indicates how long there has not been significant warming at the 95% level on various data sets. The first number in each case was sourced from WFT. However the second +/- number was taken from SkepticalScience.com
For RSS the warming is not significant for over 23 years.
For RSS: +0.127 +/-0.136 C/decade at the two sigma level from 1990
For UAH, the warming is not significant for over 19 years.
For UAH: 0.143 +/- 0.173 C/decade at the two sigma level from 1994
For Hacrut3, the warming is not significant for over 19 years.
For Hadcrut3: 0.098 +/- 0.113 C/decade at the two sigma level from 1994
For Hacrut4, the warming is not significant for over 18 years.
For Hadcrut4: 0.095 +/- 0.111 C/decade at the two sigma level from 1995
For GISS, the warming is not significant for over 17 years.
For GISS: 0.116 +/- 0.122 C/decade at the two sigma level from 1996
If you want to know the times to the nearest month that the warming is not significant for each set, they are as follows: RSS since September 1989; UAH since April 1993; Hadcrut3 since September 1993; Hadcrut4 since August 1994; GISS since October 1995 and NOAA since June 1994.
Section 3
This section shows data about 2012 in the form of tables. Each table shows the six data sources along the left, namely UAH, RSS, Hadcrut4, Hadcrut3, Hadsst2, and GISS. Along the top, are the following:
1. 2012. Below this, I indicate the present rank for 2012 on each data set.
2. Anom 1. Here I give the average anomaly for 2012.
3. Warm. 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 four have 1998 as the warmest year.
4. Anom 2. This is the average anomaly of the warmest year just to its left.
5. Month. This is the month where that particular data set showed the highest anomaly. The months are identified by the first two letters of the month and the last two numbers of the year.
6. Anom 3. This is the anomaly of the month immediately to the left.
7. 11ano. This is the average anomaly for the year 2011. (GISS and UAH were 10th warmest in 2011. All others were 13th warmest for 2011.)
Anomalies for different years:
| Source | 2012 | anom | warm | anom | month | anom | 11ano |
|---|---|---|---|---|---|---|---|
| UAH | 9th | 0.161 | 1998 | 0.419 | Ap98 | 0.66 | 0.130 |
| RSS | 11th | 0.192 | 1998 | 0.55 | Ap98 | 0.857 | 0.147 |
| Had4 | 10th | 0.436 | 2010 | 0.54 | Ja07 | 0.818 | 0.399 |
| Had3 | 10th | 0.403 | 1998 | 0.548 | Fe98 | 0.756 | 0.340 |
| sst2 | 8th | 0.342 | 1998 | 0.451 | Au98 | 0.555 | 0.273 |
| GISS | 9th | 0.56 | 2010 | 0.66 | Ja07 | 0.93 | 0.54 |
If you wish to verify all rankings, go to the following:
For UAH, see here, for RSS see here and for Hadcrut4, see here. Note the number opposite the 2012 at the bottom. Then going up to 1998, you will find that there are 9 numbers above this number. That confirms that 2012 is in 10th place. (By the way, 2001 came in at 0.433 or only 0.001 less than 0.434 for 2012, so statistically, you could say these two years are tied.)
For Hadcrut3, see here. You have to do something similar to Hadcrut4, but look at the numbers at the far right. One has to back to the 1940s to find the previous time that a Hadcrut3 record was not beaten in 10 years or less.
For Hadsst2, see here. View as for Hadcrut3. It came in 8th place with an average anomaly of 0.342, narrowly beating 2006 by 2/1000 of a degree as that came in at 0.340. In my ranking, I did not consider error bars, however 2006 and 2012 would statistically be a tie for all intents and purposes.
For GISS, see here. Check the J-D (January to December) average and then check to see how often that number is exceeded back to 1998.
For the next two tables, we again have the same six data sets, but this time the anomaly for each month is shown. [The table is split in half to fit, if you know how to compress it to fit the year, please let us know in comments The last column has the average of all points to the left.]
| Source | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| UAH | -0.134 | -0.135 | 0.051 | 0.232 | 0.179 | 0.235 |
| RSS | -0.060 | -0.123 | 0.071 | 0.330 | 0.231 | 0.337 |
| Had4 | 0.288 | 0.208 | 0.339 | 0.525 | 0.531 | 0.506 |
| Had3 | 0.206 | 0.186 | 0.290 | 0.499 | 0.483 | 0.482 |
| sst2 | 0.203 | 0.230 | 0.241 | 0.292 | 0.339 | 0.352 |
| GISS | 0.36 | 0.39 | 0.49 | 0.60 | 0.70 | 0.59 |
| Source | Jul | Aug | Sep | Oct | Nov | Dec | Avg |
|---|---|---|---|---|---|---|---|
| UAH | 0.130 | 0.208 | 0.339 | 0.333 | 0.282 | 0.202 | 0.161 |
| RSS | 0.290 | 0.254 | 0.383 | 0.294 | 0.195 | 0.101 | 0.192 |
| Had4 | 0.470 | 0.532 | 0.515 | 0.527 | 0.518 | 0.269 | 0.434 |
| Had3 | 0.445 | 0.513 | 0.514 | 0.499 | 0.482 | 0.233 | 0.403 |
| sst2 | 0.385 | 0.440 | 0.449 | 0.432 | 0.399 | 0.342 | 0.342 |
| GISS | 0.51 | 0.57 | 0.66 | 0.70 | 0.68 | 0.44 | 0.56 |
To see the above in the form of a graph, see the WFT graph below.:
Appendix
In this part, we are summarizing data for each set separately.
RSS
The slope is flat since January 1997 or 16 years and 1 month. (goes to January) RSS is 193/204 or 94.6% of the way to Ben Santer’s 17 years.
For RSS the warming is not significant for over 23 years.
For RSS: +0.127 +/-0.136 C/decade at the two sigma level from 1990.
For RSS, the average anomaly for 2012 is 0.192. This would rank 11th. 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 2011 was 0.147 and it will come in 13th.
Following are two graphs via WFT. Both show all plotted points for RSS since 1990. Then two lines are shown on the first graph. The first upward sloping line is the line from where warming is not significant at the 95% confidence level. The second straight line shows the point from where the slope is flat.
The second graph shows the above, but in addition, there are two extra lines. These show the upper and lower lines for the 95% confidence limits. Note that the lower line is almost horizontal but slopes slightly downward. This indicates that there is a slightly larger than a 5% chance that cooling has occurred since 1990 according to RSS per graph 1 and graph 2.
UAH
The slope is flat since October 2004 or 8 years, 3 months. (goes to December)
For UAH, the warming is not significant for over 19 years.
For UAH: 0.143 +/- 0.173 C/decade at the two sigma level from 1994
For UAH the average anomaly for 2012 is 0.161. This would rank 9th. 1998 was the warmest at 0.419. The highest ever monthly anomaly was in April of 1998 when it reached 0.66. The anomaly in 2011 was 0.130 and it will come in 10th.
Following are two graphs via WFT. Everything is identical as with RSS except the lines apply to UAH. Graph 1 and graph 2.
Hadcrut4
The slope is flat since November 2000 or 12 years, 2 months. (goes to December.)
For Hacrut4, the warming is not significant for over 18 years.
For Hadcrut4: 0.095 +/- 0.111 C/decade at the two sigma level from 1995
With Hadcrut4, the anomaly for 2012 is 0.436. This would rank 10th. 2010 was the warmest at 0.54. The highest ever monthly anomaly was in January of 2007 when it reached 0.818. The anomaly in 2011 was 0.399 and it will come in 13th.
Following are two graphs via WFT. Everything is identical as with RSS except the lines apply to Hadcrut4. Graph 1 and graph 2.
Hadcrut3
The slope is flat since May 1997 or 15 years, 7 months (goes to November)
For Hacrut3, the warming is not significant for over 19 years.
For Hadcrut3: 0.098 +/- 0.113 C/decade at the two sigma level from 1994
With Hadcrut3, the anomaly for 2012 is 0.403. This would rank 10th. 1998 was the warmest at 0.548. The highest ever monthly anomaly was in February of 1998 when it reached 0.756. One has to back to the 1940s to find the previous time that a Hadcrut3 record was not beaten in 10 years or less. The anomaly in 2011 was 0.340 and it will come in 13th.
Following are two graphs via WFT. Everything is identical as with RSS except the lines apply to Hadcrut3. Graph 1 and graph 2.
Hadsst2
The slope is flat since March 1997 or 15 years, 10 months. (goes to December)
The Hadsst2 anomaly for 2012 is 0.342. This would rank in 8th. 1998 was the warmest at 0.451. The highest ever monthly anomaly was in August of 1998 when it reached 0.555. The anomaly in 2011 was 0.273 and it will come in 13th.
Sorry! The only graph available for Hadsst2 is this.
GISS
The slope is flat since May 2001 or 11 years, 7 months. (goes to November)
For GISS, the warming is not significant for over 17 years.
For GISS: 0.116 +/- 0.122 C/decade at the two sigma level from 1996
The GISS anomaly for 2012 is 0.56. This would rank 9th. 2010 was the warmest at 0.66. The highest ever monthly anomaly was in January of 2007 when it reached 0.93. The anomaly in 2011 was 0.54 and it will come in 10th.
Following are two graphs via WFT. Everything is identical as with RSS except the lines apply to GISS. Graph 1 and graph 2.
Conclusion
Above, various facts have been presented along with sources from where all facts were obtained. Keep in mind that no one is entitled to their own facts. It is only in the interpretation of the facts for which legitimate discussions can take place. After looking at the above facts, do you think that we should spend billions to prevent catastrophic warming? Or do you think that we should take a “wait and see” attitude for a few years to be sure that future warming will be as catastrophic as some claim it will be? Keep in mind that even the MET office felt the need to revise its forecasts. Look at the following and keep in mind that the MET office believes that the 1998 mark will be beaten by 2017. Do you agree?
Philip Shehan says:
February 11, 2013 at 7:58 pm
Werner, You are not only cherry picking years, you are picking years and months within a very short time frame and find one set that is only just significant.
At this point in time, three of the data sets that I discussed show no warming for over 15 years, namely RSS, Hadcrut3 and Hadsst2. And three do not show this, namely GISS, UAH and Hadcrut4. It will be interesting to see what this year brings.
Philip Shehan says: February 11, 2013 at 7:58 pm
Werner, You are not only cherry picking years, you are picking years and months within a very short time frame and find one set that is only just significant. You are rather making my point for me.
I’m confused, Werner picked the longest period of time for which there has been no warming. There is only one of those for each data set, thus how can identifying and illustrating it be “cherry picking”? How would you recommend identifying and illustrating the longest period of time that there’s been no warming in each data set? How long do you think there’s been no warming in each data set?
justthefactswuwt says:
February 11, 2013 at 9:17 pm…
It’s not really whether or not a particular period shows no warming. Its whether or not a particular data set says anything meaningfull with regards to warming, cooling or stasis.
I included the period 1995 to the present because there is a concurrent discussion of this on Andrew Bolt’s website. Professor Sinclair Davidson correctly identifies that period as showing no statistically significant warming at the 95% confidence level. (Actually he was looking at hadcrut 3 data rather than hadcrut 4 as I have done):
Trend: 0.098 ±0.111 °C/decade (2σ)
What this means is that there is a 95% probability that the actual trend is between 0.209 and -0.013 °C/decade. In other words, you can’t be sure (at least at the 95% level) whether the temperature is actually warming, cooling or static over this period, not just whether or not it is warming.
Werner points out that if you look at a shorter period from 1995 to the end of 2010 rather than the the beginning of 2013 you can identify a trend (to 95% confidence) for that period and it is warming, but perhaps by as little as 0.008 °C/decade.
So for any period you choose, if you want to call the period warming, cooling or static, you need to look at the entire 95% probability range and see of the trend is positive or negative. The range will generally be narrower the longer the period you look at. (But not certainly – again because the signal to noise is lower for short periods, and the assumption here is that the trend is linear which may not hold over many decades.)
Global warming has not stalled .It never was. At least one group of climate scientists were told right at the start of the theory in the early seventies that pattern analysis showed that most of the change was entirely cyclic and that the rest was well within the level of noise that has occurred at least ten time in recorded climate information. The recent noise levels on the temperature graph makes the cyclic nature clearer than at most times, as well as showing clearly the warming phase is over and we are going into the cooler phase.
When will climate scientists start to look at the data not as climate but as patterns to be analysed using the best analysis methods available rather than their archaic filtering methods so that they can start to understand what is the difference baseline they should be using? Without this they can not hope to get a correct figure.
Also when will people stop nit picking about whether the curve is flat plus or minus a gnats whisker and have to cherry pick in both directions to decide? All we need to decide is whether the temperature is on a wildly escalating out of control feedback curve with forty eight months to doomsday or not. Anyone who believes we are should have to sign up to the idea of full compensation by climate scientists if they are wrong since they refuse to have their work external scrutinised by external examiners.
justthefactswuwt:
How about if I look for another unique attribute of each data set, such as the maximum regression slope for periods ending with the latest value (excluding periods of less than 10 years which give extreme but clearly non-significant values) and say that UAH has been rising by 2.05 C/decade since October 1991
http://www.woodfortrees.org/plot/uah/from:1991.75/plot/uah/from:1991.75/trend
and Hadcrut4 has been rising by 1.74 C/decade since December 1973
http://www.woodfortrees.org/plot/hadcrut4gl/from:1973.9/plot/hadcrut4gl/from:1973.9/trend
(and so on for other data sets). Is that not be cherry picking?
David Cage says
http://wattsupwiththat.com/2013/02/10/has-global-warming-stalled/#comment-1222903
henry says
there are not too many of us who actually seem to have figured out that natural cycle/
I did, but only found it by looking at maxima…
which NOBODY has done, yet….and is still not doing.
http://blogs.24.com/henryp/2012/10/02/best-sine-wave-fit-for-the-drop-in-global-maximum-temperatures/
Henry@Werner
Nice job.
Still, I would consider throwing out UAH as it does not fit in with any of the other data sets, including my own.
All data sets including my own show a negative trend over the past 11-12 years (which is the equivalent of at least one complete solar cycle period) – meaning that we have entered a cooling off period.
http://www.woodfortrees.org/plot/hadcrut4gl/from:2002/to:2013/plot/hadcrut4gl/from:2002/to:2013/trend/plot/hadcrut3vgl/from:2002/to:2013/plot/hadcrut3vgl/from:2002/to:2013/trend/plot/rss/from:2002/to:2013/plot/rss/from:2002/to:2013/trend/plot/gistemp/from:2002/to:2013/plot/gistemp/from:2002/to:2013/trend/plot/hadsst2gl/from:2002/to:2013/plot/hadsst2gl/from:2002/to:2013/trend
“David Cage says:
February 11, 2013 at 11:42 pm
…Anyone who believes we are should have to sign up to the idea of full compensation by climate scientists if they are wrong since they refuse to have their work external scrutinised by external examiners.”
The idea that scientists, climate or otherwise, refuse to have their work scrutinised by “external examiners” or anyone else is complete nonsense.
The entire scientific project rests on the publicaton, discussion and challenging of results and theories which is precisely what is going on here.
Who are these “external examiners” to be? Presumably they would have to be people who are most qualified to understand the science. Scientists in fact. And who is going to appoint them? Governments? “Independent” think tanks? Industry? Conservation groups?
And as for compensation, are skeptics to be made to pay for losses incured if the majority of climate scientists are right.
In Italy we have had the ludicrous situation where scientists have been convicted of a criminal offense because they were not “alarmist” enough about the possibility of an earthquake occuring.
There is an update on the BBC story about parts of Africa becoming 3.5 deg.C warmer in just 20 years.
The Guardian correspondent, Leo Hickman. has got the bit between his teeth on this one and is intent on tracking down where this erroneous statement came from (yes, I said Guardian).
After following the ‘evidence’ from one green lobby group to another it all comes down to a single weather station in Africa, at Kericho.
But then, thanks to Dr Menno Bouma at the London School of Hygiene and Tropical Medicine, he discovered that there were known problems with the Kericho temperature record
http://www.guardian.co.uk/environment/blog/2013/feb/08/bbc-global-warming-attenborough-africa
Nigel Harris says:
February 12, 2013 at 1:28 am
justthefactswuwt:
“How about if I look for another unique attribute of each data set, such as the maximum regression slope for periods ending with the latest value (excluding periods of less than 10 years which give extreme but clearly non-significant values) and say that UAH has been rising by 2.05 C/decade since October 1991
http://www.woodfortrees.org/plot/uah/from:1991.75/plot/uah/from:1991.75/trend
and Hadcrut4 has been rising by 1.74 C/decade since December 1973
http://www.woodfortrees.org/plot/hadcrut4gl/from:1973.9/plot/hadcrut4gl/from:1973.9/trend
(and so on for other data sets). Is that not be cherry picking?”
Not cherry picking, just wrong by a factor of 10. The trends you are referring to are 0.204 +/- 0.150 C/decade, for UAH, and 0.175 +/- 0.035 C/decade. These figures are from the skeptical science trend calculator.
2.05 C/decade would give a rise of 20.5 degrees C over 100 years.
And the answer to your question is no, it’s not cherry picking. These two trends exist. What of them? What’s your point?
Philip Shehan says: February 11, 2013 at 9:49 pm
It’s not really whether or not a particular period shows no warming. Its whether or not a particular data set says anything meaningfull with regards to warming, cooling or stasis.
I completely agree with your second sentence, in that our temperature records are laughably brief and burdened with issues of questionable siting, changes in siting, changes in equipment, changes in the number of measurement locations, modeling to fill in gaps in measurement locations, corrections to account for missing, erroneous or biased measurements, the urban heat island effect and increased “noise” in the case of satellites. As such drawing any conclusions with confidence is difficult. However, given that some are making erroneous claims about rapid global warming based on these questionable data sets, we have no choice but to use them to demonstrate that the data does not in fact support these erroneous claims.
With this said, you’re the one who accused Werner of “cherry picking”, and I still don’t understand your point. If Werner’s goal is to demonstrate the longest period for each data set where there has been no warming, how is it possible that he is cherry picking?
Nigel Harris says: February 12, 2013 at 1:28 am
How about if I look for another unique attribute of each data set, such as the maximum regression slope for periods ending with the latest value (excluding periods of less than 10 years which give extreme but clearly non-significant values) and say that UAH has been rising by 2.05 C/decade since October 1991
http://www.woodfortrees.org/plot/uah/from:1991.75/plot/uah/from:1991.75/trend
and Hadcrut4 has been rising by 1.74 C/decade since December 1973
http://www.woodfortrees.org/plot/hadcrut4gl/from:1973.9/plot/hadcrut4gl/from:1973.9/trend
(and so on for other data sets). Is that not be cherry picking?
No, that would be identifying the maximum regression slope for each data set. We seem to be struggling with the definition of cherry pick here. Identifying a unique attribute of a data set is not cherry picking. Arbitrarily selecting a period of analysis because that period happens to support your conclusions is cherry picking. There is nothing arbitrary about what Werner has done, he has identified the longest period of time to present for which there has been no warming in each data set. How would you recommend identifying and illustrating the longest period of time that there’s been no warming in each data set? How long do you think there’s been no warming in each data set?
justthefactswuwt says:
February 12, 2013 at 5:31 am…
Perhaps “cherry picking” was the wrong term but the point is that going back to find when global warming has “stalled” is not likely to be usefull unless you are limited to time periods that give a statistically significant result. So unless Werner has done such of an analysis on his flat data sets they are not telling us much.
Forgive me for not doing this using the program I have given above but it is 12:50 am here in Melbourne so I think I will retire for the night.
Nigel Harris says:
February 12, 2013 at 1:28 am
justthefactswuwt:
P.S: As I’ve said already, the trend in the HADCRUT 4 data from 1863 – present, is 0.051 +/- 0.007 C/decade. So there is only a 5% chance that the trend over this entire time period is greater than 0.058 C/decade. Nevertheless, if you look at shorter time periods within that 150 year period, you will find higher trends, like the ones you have. So clearly temperatures haven’t and don’t just go up in a straight line. You can see that just from looking at a graph of the data over the 150 years.
If there are short term trends higher than this 0.051 C/decade, with 95% confidence (and there are, for instance 1975 – 1991 in the HADCRUT 4 data) then there MUST be lower short-term trends to balance it all out. It’s just that you can’t discern these lower or zero or slightly negative short trends from the noise because the computed trends are inevitably going to be lower than their 95% confidence intervals. I mean how long a period with a “trend” of very near to zero would you need to have to be 95% sure it was a trend, in this noisy data!? 50 years? 100 years? How likely is that to happen!? This doesn’t mean that these near zero trends can’t exist [and in fact, they MUST do as I have demonstrated], and that it’s just “cherry picking” to point out trends that are statistically-indistinguishable from zero.
Shehan says:
“So unless Werner has done such of an analysis on his flat data sets they are not telling us much.”
Given that Shehan has done NO analysis on anything, we can dismiss his pseudo-scientific conjectures out of hand, as rank amateur nonsense.
Of course global warming has stalled. Only blinkered idiots believe otherwise. Empirical data tells the truth — unlike climate alarmists, who feel the need to lie because the planet is not cooperating with their false narrative.
Werner Brozek says:
February 11, 2013 at 7:59 pm
Phil. says:
February 11, 2013 at 6:57 pm
Werner based on the ‘one tailed’ test all of those examples show significant warming at the 95% level.
Phil, I appreciate your help, and from earlier comments, I understand where you are coming from. I realize your expertise in statistics is greater than mine and I see no reason to dispute the above statement. I checked the site at: http://www.skepticalscience.com/trend.php
I found this statement with regards to using this site:
“What can you do with it?
That’s up to you, but here are some possibilities:
Examine how long a period is required to identify a recent trend significantly different from zero.”
You may recall Phil Jones’ comments in 2010 that the warming was not significant for 15 years from 1995 to 2009, but later said it was significant for 16 years from 2009 to 2010.
Actually as part of a BBC interview Jones was asked the question which had be submitted by Lindzen:
“Do you agree that from 1995 to the present there has been no statistically-significant global warming?”
To which Jones answered that it was only just below the 95% significance level because of the shortness of the period and would likely become significant when more data was added. A point he confirmed when the next year’s data was added.
The only thing that makes sense to me is that he used the ‘two tailed’ test that skeptical science uses. Would you agree with that? I appreciate you informing me that I cannot mention the 95%. I will therefore play it safe and say that according to the skeptical science site, such and such is where the trend is “significantly different from zero”. Does the skeptical science site do things wrongly? Perhaps, although I am not in a position to judge that.
It probably was a ‘two tailed’ test however as stated above that makes no sense to me. In all the data you’ve presented above the probability of the true trend being zero or below is around 3% or less, so the null hypothesis of ‘not warming’ is rejected at the 95% level. To cobble that together with the finding that there is a 3% probability that the trend exceeds 0.25 (say) therefore the chance of ‘not warming’ now falls below 95% is nonsense. If you have a normally distributed variable the answer to the question ‘what is the chance that the value is below 2 sigma below the mean?’ is ~0.25%, the answer to the question ‘what is the chance that the value is outside the range of 2 sigma from the mean?’ is ~5%. Those are not the same question and therefore don’t have the same answer! To those who analyse the data in the way you have and then use the result to say that ‘there is no warming’ I could say with equal accuracy that the data means that ‘there is warming in excess of 0.264 (for the Hadcrut data I think). I think that illustrates the error in making such a claim. Based on the actual data analysis that you have done we can say that there is more than a 20:1 chance that warming continued over the period.
HenryP says:
February 12, 2013 at 1:44 am
I would consider throwing out UAH as it does not fit in with any of the other data sets, including my own.
The latest straight line of 4 years and 7 months certainly looks extremely out of place, but it would not take too many cool months to get that to around 11 years. Let us see what version 6 shows.
UAH is using version 5.5, however a more accurate version 6 has been in the works for a while, but it is not completed. Hopefully it will narrow the gap when it is done.
From Dr. Spencer on January 3, 2012:
“I’m making very good progress on the Version 6 of the global temperature dataset, and it looks like the new diurnal drift correction method is working for AMSU. Next is to apply the new AMSU-based corrections to the older (pre-August 1998) MSU data.”
Philip Shehan says:
February 12, 2013 at 5:50 am
So unless Werner has done such of an analysis on his flat data sets they are not telling us much.
I have done no analysis. I just let NOAA tell me how big the goal post was, namely 15 years of 0 slope and I have just confirmed that Earth scored a goal on three of the data sets. For all I know, NOAA could be wrong. You would need to take that up with them.
Phil. says:
February 12, 2013 at 6:28 am
To which Jones answered that it was only just below the 95% significance level because of the shortness of the period and would likely become significant when more data was added. A point he confirmed when the next year’s data was added.
We also cannot ignore the fact that 2010 was extremely warm. In fact, two of the data sets show 2010 as the warmest on record. However the warming was no longer significant at the end of 2011 and 2012 since they cooled off. So the extra years did not help here.
To those who analyse the data in the way you have and then use the result to say that ‘there is no warming’ I could say with equal accuracy that the data means that ‘there is warming in excess of 0.264
I agree with you. I should have said that according to skeptical science, this is the period that is not “significantly different from zero”. It seems that we are dealing with two different definitions, each of which has its own validity, depending on the purposes. If you feel skeptical science is doing things wrongly, by all means, take it up with them. In the meantime, I am not a statistician, and I am forced to use tools at my disposal.
Regards
UPDATES
We do not have any update from WFT for GISS and Hadcrut3 for December, however this site has now been updated to the end of December: http://www.skepticalscience.com/trend.php
In the report, I said:
1. For GISS, the slope is flat since May 2001 or 11 years, 7 months. (goes to November)
2. For Hadcrut3, the slope is flat since May 1997 or 15 years, 7 months. (goes to November)
With the update, that is now changed to:
1. For GISS, the slope is flat since March 2001 or 11 years, 10 months. (goes to December)
2. For Hadcrut3, the slope is flat since March 1997 or 15 years, 10 months. (goes to December) (The slope is 0.000/decade here)
In addition, all parts of section 2 are changed slightly, however I do not think it is worth commenting on a change in the third decimal place or a change of a single month. However GISS changed from October 1995 to June 1995 for the period where there has not been significant warming according to their criteria.
Oh heck. He who thinks that abuse is a substitute for scientific argument has tracked me down again.
“Given that Shehan has done NO analysis on anything, we can dismiss his pseudo-scientific conjectures out of hand, as rank amateur nonsense… Empirical data tells the truth — unlike climate alarmists, who feel the need to lie because the planet is not cooperating with their false narrative.”
Actually anyone who has taken even a cursory glance at my posts here can see I have done a great deal more analysis of the empirical data than the Great Abuser. But he never lets the facts get in the way of his manure shoveling.
Anyway, let’s just take a different perspective on his graph. Excuse me for substituting Hadcrut 4 data for RSS but the latter does not go back to 1958 when Muana Loa data began.
http://tinyurl.com/a7pv4th
As it happens, the Hadcrut 4 data shows a positive trend for the period GA chooses:
Trend: 0.038 ±0.137 °C/decade (2σ)
So GA can accept on this basis of this empirical data that warming has not stalled, or that what the data is really showing is that there is a 95% probability that warming of as much as 0.175 or cooling of -0.099 °C/decade has occurred.
Philip Shehan says:
February 12, 2013 at 2:03 pm
Excuse me for substituting Hadcrut 4 data for RSS but the latter does not go back to 1958
Trend: 0.038 ±0.137 °C/decade (2σ)
Is there any reason you did not take Hadcrut3? For the same period, it gives
Trend: -0.010 ±0.146 °C/decade (2σ)
However even going with 0.38/century, that is way less than 2/century, so it is obviously nothing to worry about, right?
Werner Brozek,
Thank you for your excellent article. No one knows if, or when, global warming will resume, or if global cooling will follow. What we do know is that currently, global warming has stalled.
Next, you should not waste your time trying to educate Philip Shehan, it is an impossible task. He still insists that global warming is accelerating [he climbed down from that false assertion until he was called on it — then he went right back to posting his fabricated SkS chart purportedly showing a bogus ‘acceleration’ of global warming]. Shehan can post all the nonsense he wants, but if he still insists that global warming is accelerating, he will get challenged with verifiable facts. The fact is that global warming has remained on the same trend line since the LIA. It has never “accelerated”. The long term natural warming trend is ≈0.3º/century.
Finally, HadCRUT3 is not used because it began showing uncomfortable facts, so version 4 was substituted.
Werner:
No reason at all not to use Hadcrut3. Its just I had been using Hadcrut4 in my earlier analysis and I assume 4 is the new improved version but all the data sets are close enough. Preferring one data set over another is another example of cherry picking. But this is another way of making my point here. Over multidecal time periods, these data sets are so similar that cherry picking is rather pointless.
And yes, an increase of 0.38 over the next century would not be cause for concern, but the point I am making is the 95% range for that fit is 1.75 to -0.99 C per century (on the dubious assumption that the trend is linear over a century)
For the Hadcrut3 data the trend is a drop of 0.1 C per century within a range of 1.36 to -1.56 C.
The point here is that although one data set predicts a small rise in trend and the other a small drop, the uncertainties in short term trends make this distinction next to meaningless.
Global warming has not stalled, and Global warming is not a question to wait out; it is a fact, and it is happening. Strings of warm temperatures are unlikely to be due by chance. Small sets of data are meaningless in this case, and a trend in data must be examined over millions of years, not recent peaks or troughs. By doing this you will see that the trend proves that the annual temperature is increasing. Further proof of global warming is in the melting of Arctic snow and ice. In fact, the current extent of summer ice is so low near the poles that a Northwest passage has been opened. More proof lies in the biosphere. The biosphere is not waiting to be told that it is warmer, it is already responding. For instance, the growing season between 45 and 70 degrees N latitude has lengthened by about 10 days (warmer temperatures affect plant growth positively). Migration patterns of British birds have extended their ranges northward by about 19km over the last 20 years. And hibernation yellow-bellied marmots emerge 38 days earlier in the Rocky mountains. Global warming is not a question, it is a fact. There are many examples of the biosphere changing and responding due to warmer temperature. It seems ever creature is acting and adapting to the warming climate except for humans, who ironically, are the number one cause of warming.
Earth to Rachel:
Global warming has stalled. That is a fact.
Sorry about your belief system. Reality intrudes.