Has Global Warming Stalled?

Graham: First, apologies – still have not found the particular reference I mentioned above. 7 pm here in Melbourne as I am typing this and been busy today.
Generally, climate theory has always acknowledged that climate depends on anthropogenic and natural factors. When people first began to postulate that increasing CO2 and other greenhouse gases would cause warming they recognised that at that time the anthropogenic signal was not detectable from the natural forcings.
The Melbourne University climate scientist David Karoly first became interested in the climate change question believing he could account for changes using natural forcings only. He found he could not and thus became one of those who accept AGW.
In 1981 Hansen thought a clear anthropogenic signal may emerge in the 80’s but possibly not until the end of the century.
http://pubs.giss.nasa.gov/docs/1981/1981_Hansen_etal.pdf
“Summary. The global temperature rose by 0.20C between the middle 1960’s and
1980, yielding a warming of 0.4°C in the past century. This temperature increase is
consistent with the calculated greenhouse effect due to measured increases of
atmospheric carbon dioxide. Variations of volcanic aerosols and possibly solar
luminosity appear to be primary causes of observed fluctuations about the mean trend
of increasing temperature. It is shown that the anthropogenic carbon dioxide warming
should emerge from the noise level of natural climate variability by the end of the
century, and there is a high probability of warming in the 1980’s…”
Of course climate models which evaluated the various contributions were rudimentary then and this 1981 paper considers only CO2 ,volacanoes and the sun but gave a pretty good fit for temperature data up till then (Fig 5 ).
In the last 3 decades work has been continually done to refine the theory and the models. My post above gave examples of these refinements from 2001 and 2006. It has not happened recently to account for a slowdown of warming in the last decade.
No one with any knowledge of the science has ever thought that global temperatures can be explained by increases in greenhouse gases alone.

Thanks for the response Philip. I would say though that the crux of your post is this:
“No one with any knowledge of the science has ever thought that global temperatures can be explained by increases in greenhouse gases alone.”
And I’d just like to remind you that this is not what I was suggesting either. I said:
“Isn’t the idea of natural forcings not having such a cooling effect over the 70s to late 90s warming period and then suddenly having a cooling effect like they supposedly have now less logical than the idea of CO2 having little effect and climate change being dominated by natural forcings? Because if you argue that the natural forcings changed from being positive over that period to being negative (or lower) recently to try to defend the former position, then that explanation would also apply to the latter position…only the latter position also makes more sense being as how CO2 levels have risen at an increasing rate?”
So the “former position” I am referring to is this idea that natural forcings have recently over-shadowed, if that’s the right word (probably not) the effect of CO2 whereas over the 70s to late 90s warming period this was not the case. This is implied by your statement “The apparent change recently have been explained by the contribution of natural forcings (solar cycles, el nino/la nina etc) which are giving a cooling contribution”, since if the forcings are having this cooling effect now, why didn’t they previously? Then, anticipating a response, I continued “if you argue that the natural forcings changed from being positive over that period to being negative (or lower) recently to try to defend the former position, then that explanation would also apply to the latter position…only the latter position also makes more sense being as how CO2 levels have risen at an increasing rate?”
The “latter position” referring to the idea that CO2 levels have little effect and climate change is dominated by natural forcings.
Nowhere in my comments have I argued that anyone suggests “global temperatures can be explained by increases in greenhouse gases alone”.
As for the points you have made at the end of your post of February 14th at 3:55am, specifically:
“I would be very surprised if any data set since 1995 did not include zero”.
It would surprise me an enormous amount if a trend since 1995 DID include zero, if the computed trend was higher than the typical 95% level usually associated with whatever time frame you’re looking at! What I’m trying to say is, take for example the HADCRUT 4 data, a typical 15 year period (more recently) will tend to have error bars in the area of +/- 0.125 or something close to that. So if the true trend in the data was any greater than this, the computed trend for the data would be discernible from zero with 95% confidence (the result would be a positive trend greater than its associated error margin). If the true trend was still the 0.17 C/decade that people claim applies to the last 30 years, then this trend would still be “visible” above the noise even over 15 years…but it isn’t. This shows us that the rate of warming has certainly decreased, more recently. There is then a need to investigate and explain why this is happening…and then you’re back to the points I’ve already made in my previous comment of February 13th, 6:03pm, and clarified further at the beginning of this one.

P.S (to post to Philip Shehan):
The trend in HADCRUT 4 data from 1975 – 1990 is 0.184 +/-0.141. The trend from 1975 – 1991 is 0.207 +/- 0.129. The trend from 1995 – 2013 is 0.095 +/- 0.110. The trend from 1975 – 2013 is 0.169 +/- 0.037. I hope, considering the points I have made, this makes sense as to what I’m suggesting with these trends…it’s clear the rate of warming has recently slowed.

Graham W says:
February 14, 2013 at 5:36 am
It would surprise me an enormous amount if a trend since 1995 DID include zero,
The trend for Hadcrut3 from March 1997 (1997.17) to 2013 is:
Trend: 0.000 ±0.135 °C/decade (2σ)
This means there has been no warming on Hadcrut3 for 15 years and 10 months. Right?

Werner, thanks for this article! Yes it’s most likely that there’s no warming with the trend you’ve posted in your response to me. However you’ve taken my quote out of context there a bit, what I’ve said only makes sense if you add in the rest of the sentence (well it makes sense as you’ve written it but its not what I’m saying).
What I was trying to say to Philip Shehan is that you won’t get a trend where the error bars include zero if the computed trend is greater than the error bars. So in other words if you have a trend of say 0.143 +/- 0.142, then zero is not an option at the 95% confidence level. Hence the trend is statistically discernible from zero with 95% confidence and you know there will be some degree of warming.
And the point I was making by saying that was, if the true trend in the data was 0.17 C, then you would get a statistically significant (i.e statistically discernible from zero) result even over a short length of time such as 15 years…because the typical error bars for such a length of time are around 0.12 or 0.13 C/decade above and beneath the computed trend (in HADCRUT 4 data for 15 year periods). The fact that this is not happening in recent periods but DID happen in prior periods suggests (in fact proves for certain) that the rate of warming has slowed.
Slowed/stalled, whatever you like. Basically the opposite of what was projected to happen with an increasing rate of CO2 level increase.

Graham W says:
“Slowed/stalled, whatever you like. Basically the opposite of what was projected to happen with an increasing rate of CO2 level increase.”
That is the central point in the entire debate. All the predictions of runaway global warming due to rising CO2 have been falsified.
Empirical evidence shows conclusively that CO2 does not have the effect predicted by the alarmist crowd.
It turns out that the putative ‘correlation’ between T and CO2 was nothing but a short term coincidence. Thus, the entire basis for the AGW scare has been deconstructed. The only empirical measurements between CO2 and T show that ∆T causes ∆CO2; not vice-versa.
The alarmist crowd started off with the incorrect premise that ∆CO2 was the cause of ∆T, therefore, the conclusions based on that false premise are necessarily wrong. That is precisely what the planet is telling us. But alarmists have so much of their ego and their belief system tied up in the incorrect assumption that CO2 causes temperature changes, that they cannot gracefully withdraw from the argument. But most WUWT readers know the truth.

I would like to express my thanks to JTF and Anthony Watts along with all who have added their thoughts so far.
JTF, If there was ever any doubt about the attention grabbing abilities of the graphic at the start of the article, I believe it has been settled since I was very pleased to see that even Andrew Bolt from Australia used it, (along with many other facts from the article).
See:
http://blogs.news.com.au/heraldsun/andrewbolt/index.php/heraldsun/comments/craig_emerson_was_wrong_on_global_warming_and_must_retract/

Graham, I was not suggesting that you needed reminding that climatologists have always known and said that climate is multifactorial, but I often think others do.
With regard to your comment (and forgive me if this is not the gist of what you are saying) I think it is incorrect to say that it is only latterly that particular emphasis has been made as to how “natural” forcings affect temperature. The extent to which natural forcings combine to override an increase due to rising CO2 concentration varies from time to time.
If you have a “perfect storm” of cooling events occurring at the same time, such as volcanic eruption, a low point in the solar cycle and an el nino event you will get a dramatic total cooling effect. At other times the natural forcings partially cancel or give a positive contribution (eg the extreme el nino southern summer of 1997/1998).
And dramatic cooling periods have occurred in the past. To quote from one of my posts above:
“The temperature behaviour before and after 1945 is another demonstration of what I have been saying. The temperatures seem to drop off a cliff for the 16 year period after 1940 but recover and continue an upward trend thereafter, with a similar slope as for the period 1910 to 1940.
http://www.woodfortrees.org/plot/hadcrut3vgl/compress:12/offset/plot/hadcrut3vgl/from:1850/to:2010/trend/offset/plot/hadcrut3vgl/from:1940/to:1956/trend
If you look at the models I gave in the above posts none of them seem to adequately account for the local peak around 1940 with or without the AGW contribution. I submit that the models are pretty good at hindcasting otherwise but obviously there are some things they cannot account for yet.”
Since I wrote that I came across a possible explanation of the models to fully account for the local peak
“The biggest disagreement is just prior to and during world war II, when the method of measuring sea surface temperature changed, which may have caused a discrepancy in the observed temperature data.”
http://web.archive.org/web/20100322194954/http://tamino.wordpress.com/2010/01/13/models-2/
Of course as CO2 concentrations rise with time and the positive contribution from that forcing becomes larger, periods when a combination of negative forcings can overide that effect will become rarer.

Thank you, Graham. I have no doubt that scientific skeptics are right. None at all.
But Shehan — contrary to all scientific evidence — remains a True Believer:
“Of course as CO2 concentrations rise with time and the positive contribution from that forcing becomes larger, periods when a combination of negative forcings can overide that effect will become rarer.”
Translation: ‘Global warming causes the observed global cooling. Pay no attention to the fact that the planet is falsifying our alarmist case. Somehow, catastrophic AGW must still be true!’
Cognitive dissonance in action.

Philip Shehan: My point was that a cooling or warming effect of “natural forcings” (here defined as “all climate forcings bar anthropogenic CO2”) will have always affected the climate regardless of anthropogenic CO2.
Now, there is a period of relatively rapid increase in temperatures from the 70s to the 90s, and subsequent to that (90s to present) this period we are identifying as a time of relatively reduced temperature increase/possibly “stalled” temperatures…and also possibly, at least for a part of the most recent time, cooling temperatures!
The difference between the rate of rise in temperatures over these periods could be explained in different ways. Let’s say at one extreme end of these “different ways”, climate sensitivity to CO2 is very high, and at the other end of the spectrum, climate sensitivity to CO2 is very low (even non-existent).
With both extremes, and with everything inbetween, the difference in rate of rise in temperatures can be accounted for by variation in the warming or cooling effect of natural forcings, to different extents. However, and this is the crux of my entire point really: it is surely more logical to opt for the low end of the “sensitivity to CO2” spectrum since if the sensitivity to CO2 was higher, the fact of such rapidly rising CO2 levels over the entire time period examined (1970-present) would outweigh the effect from natural forcings (since that’s what a high climate sensitivity to CO2 means in the first place)…but this has not been shown to be what has happened/is happening as far as the temperature response is concerned.
You are then arguing about what has happened in the past – back to the 40s to 70s era – but the levels of CO2 in the atmosphere were far less back then compared to what has been happening with CO2 levels over the period from the 70s to the present. Hence, back then, natural climate forcings should have dominated climate change more so than they do now (assuming higher climate sensitivity to CO2). So if anything, that adds to the skeptic argument, rather than detracting from it. We should be even less likely to be seeing a reduction in rate of temperature rise now than we did back then, if climate sensitivity to CO2 is high.
So climate sensitivity to CO2 must be at the lower end of the spectrum. Exactly how low is hard to say, but it is more logical for it to be lower and not higher for these reasons.

Hello JTF,
I will do the three tables in a vertical format for next time. Of course this would reduce it to two tables. Naturally the one table will be much shorter at the start of the year since there are far fewer months to show. But with the vertical format, extra months can easily be added without running out of room at the side. It has the further advantage that I can write “2012 anomaly” instead of “anom1” to save space and then explain what it says.
I will of course make all edits. But as near as I can tell, SkS updates every two months, so if you want an update every month, some things such as the longest time there is no significant warming will not change every month.
Then there is the problem with WFT. GISS, Hadcrut3 and WTI are still not updated past November. As I alluded to above, I can use SkS which I did for the December slope for GISS and Hadcrut3. WTI can be done, but it is extremely awkward without WFT and I doubt it is worth the effort.
As for the month/date/time, sometimes the Hadcrut3 and 4 values come out sooner and sometimes later. I think the best thing to do is wait for these to show up and then I could send you an email and have the new post show up the following Sunday at the usual time. I have no problem doing it every month, but I just wonder if things change enough to warrant it. For example, if the period of significance changes in the third decimal place or if the time for a straight line changes from 11 years and 7 months to 11 years and 9 months, is it worth a new post to mention this? We could certainly try it monthly and see how the interest is. How about if we have a post after all January data is in and then play it by ear? Perhaps every two or three months may be more appropriate?
You had mentioned your own article at one time where you wanted to incorporate some of my stuff. Just send me an email when you want the very latest from me for anything in this post.

Corey. I am not defelecting from the data, I am subjecting it to statistical analysis. As a biomedical research sceintist, I have some understanding of these matters.
With all due respect to Werner and his efforts, there is a falure to recognise that the concept of statistical significance is largely dependent on sample size. If the sample size is too small you are wasting time and effort and establishing nothing of importance.
One extreme example of that here is the person who examined the last five years, which shows that over the next century, temperatutes might rise by about 6 C. Or fall by about 6 C. You have to look at 30 decades to come up with a sufficiaently small error range to decide whether temperatures are rising or falling with atrend that can be considered as having some accuracy.
I have recently been involved in a clinical trial for a medical treatment, double blind, with hundreds of subjects.
No one in their right mind would declare on the basis of 16 subjects that the medication was or was not effective.

PS. I think I can state without violating any confidentiality agreements that preliminary results indciate the treatment to be highly effective (one might even hazard using the term “cure”) for a very serious and widespread disease.