Monday
Sep052011
by 
Bishop Hill
Bishop Hill Santer says
Sep 5, 2011 Climate: Models Santer et al have a new paper out on trends in the tropospheric temperature.
Because of the pronounced effect of interannual noise on decadal trends, a multi-model ensemble of anthropogenically-forced simulations displays many 10-year periods with little warming. A single decade of observational TLT data is therefore inadequate for identifying a slowly evolving anthropogenic warming signal. Our results show that temperature records of at least 17 years in length are required for identifying human effects on global-mean tropospheric temperature.
Please keep comments to the subject matter of the paper.
Reader Comments (163)
17 authors needed to write one paper! Unbelievable.
Multi-model ensembles are worthless. The more so as all the models are all unvalidated and have all been arbitrarily tuned in different ways to historical data.
How did this paper get through peer-review? I suggest the editor resign immediately. There is an excellently written letter in existence that he could plagiarise to his personal needs.
Sorry Bish, I strayed off topic at the end there.
"Our results show that temperature records of at least 17 years in length are required for identifying human effects on global-mean tropospheric temperature."
So we can carry on ignoring the lack of warming since 1998 for a bit longer?
"Trends >17 yrs are required for identifying human effects on tropospheric temp."
With no statistically significant warming since 1995 is the case now (almost) closed?
@MarcH
I'm guessing they'll choose 1998 as their baseline and then as we get closer to 2015 papers will be released to stretch the window to 20 years, 25 years and ever upwards. I'd put money on it.
From Santer:
A single decade of observational TLT data is therefore inadequate for identifying a slowly evolving anthropogenic warming signal.
The Team needs to get its act together. According to Solomon et al (2011) and Kaufman et al (2011), anthropogenic forcings are instantaneous on the climate, at least in the case of aerosols.
Kaufman et al (with the al including Mann), only used a 10 year data set (1998-2008), but was able to determine an anthropogenic cause for the lack of anthropogenic warming.
MarcH:"With no statistically significant warming since 1995 is the case now (almost) closed?"
I believe you'll find there are two new papers in the process of publication. Paper 1 extends the period to 17 years 364 days and 23 hours, but is merely a holding paper for Paper 2 which through the use of sophisticated statistical methodology, (which will, unfortunately not be available for scrutiny) will prove beyond doubt that if the anthropogenic signal has not been detected over any timescale it is only two years away from doing so. The paper goes on to prove, again using sophisticated statistical methodology, and again, unforturnately unvavailable for scrutiny, that this two year period will always be there on any timescale and that this indeed proves that there is an anthropogenic signal, we just cannot see it at any given time. Nobel prizes all round.
Clarification/correction: the Mann in the Kaufman et al paper is apparently not the same Mann we all know and love....
Does this mean they can not attribute the rise in temperatures through the 90's to AGW?
"Over 1979–2003, the satellite‐equivalent tropical lower tropospheric temperature trend has likely (5–95% confidence range) been between −0.01 K/decade and 0.19 K/decade (0.05–0.23 K/decade over 1958–2003) with a best estimate of 0.08 K/decade (0.14 K/decade)".
So it's all settled then.
Geoff, how much imagination goes in to creating a "satellite equivalent", and has Hansen had his sticky fingers anywhere near it?
golf charley
Correct, it does indeed work both ways - you need more than a few years to say anything sensible, whether it's cooling, flatlining or warming.
However, the rise in temperatures since the early 1970s can be attributed largely to AGW. It's the decade-by-decade signal that is important - 1980s warmer than 1970s, 1990s warmer than 1980s, and 2000s warmer than 1990s.
I am no fan of Kuhn, and calling these guys' dogma a paradigm is a bit too much, but there is a short summary of response to crisis in Kuhn's "Theory of scientific revolutions" that looks suitable:
from here
In this case, what Santer is doing is trying desperately to buy some time. Santer, however, is the right person to do it, given his ability to stretch error bars beyond the limits of most humans imagination, to make them suit his needs.
However, the rise in temperatures since the early 1970s can be attributed largely to AGW.
Sorry but the steepness of the temp increase from the early 70's is the same as the previous 30 year temp increase in the 20 C before 1945, so what is so different between the 2 increases and why is the second CO2 and the first not CO2.
The reason Dr Jones gave was they could not think of any other reason so it had to be CO2, hardly proof of anything other than 'We must look harder'
"On an individual pressure level basis, agreement between models, theory, and observations within the troposphere is uncertain over 1979 to 2003 and nonexistent above 300 hPa".
So Douglass, Christy, Pearson Singer , McKitrick, McIntyre, Herman, and Vogelsang were correct then.
My Tuppence worth,
Santer attempts to apply another Band Aid/Sticking plaster to ailing climate model 'scientology'. Model 'skill' to date, zero, Santer et al credibility to date likewise.
17 authors, I'm amazed at how much academic effort is required to keep "End of the World is nigh" climate theory alive. Maybe they've discovered a way of making money out of it. ;)
Still beats working for a living.
Richard Betts, you say:
Sorry, I mucked up there:
The only support I have seen for this type of opinion comes from models and that is not evidence. What is the specific evidence and where can I find it please? Does this evidence include correct cloud modelling, correct effect of cosmic rays and correct effect of ocean cycles?
Cheer up chaps!
"A single decade of observational TLT data is therefore inadequate for identifying a slowly evolving anthropogenic warming signal. Our results show that temperature records of at least 17 years in length are required for identifying human effects on global-mean tropospheric temperature."
= "it's not as bad as we thought".
I'd bank those words.
Neil McEvoy
Are you referring to the temperature change or the underlying science?
If it takes 17years to identify AGW, how long does it take to identify GW.
Something else which is keeping me awake at night and could use a similar insightful calculation from Ben.
How many hairs constitute a beard?
asnswers on a post card please.
What are the mechanisms of oscillations in the models? A cynic might imagine that this is a feature of a numerically unstable model. Until this can be explained, I don't see what this says except that the models produce low frequency noise.
On one hand, this is clearly 'moving the goal posts" or CYA-ing. Furthermore, if a few more years pass without massive global warming, it reaches the point of no return (ie, falsification), again.
What's the use?
On the other hand, doesn't Fred Singer have some useful observations about models from his recent talk in Brussels? SEE notrickszone.com by Pierre Gosselin:
http://notrickszone.com/2011/09/03/fred-singer-at-suppressed-seii-presentation-1976-to-2000-warming-thats-fake-it-doesnt-exist/
IPCC climate models cannot be validated because they have too few runs. And their min-max variations to broad to make them useful.
Therefore, what becomes of Santer's proclamations?
I wonder at the motivations behind Santer's [et al] paper, statisticians and statistics don't ever prove anything.
Only through, empirical science and testing observed results time and again can postulations be truly tested.
It all smacks of, arguing over canapes and dinner table settings - in a hotel that is burning to the ground.
I guess this has been written to address amongst other things the "lack of recent warming". Personally I would tend to agree with Santer that the use of shorter periods could be misleading. This is particularly true if data outside the period being reviewed is ignored. There has been a prior history of people ignoring inconvenient data and a very good example of this is described in this article written by a person we know Ben Santer admired
http://www.john-daly.com/sonde.htm
GC, the temperature change. The underlying 'science' is still based on random numbers with various biases to get the 'right' result, but now constrained to maintain a semblance of plausibility.
The global temperature is where it was 20 years ago, in 1991, in the NOAA NCEP SST and UAH satellite data.
What Santer et al. and Richard Betts are saying is that comparing each decade to the previous one is more revealing than comparing each decade with itself. This is easy to visualise.
First, here's the full satellite record 1979 - present:
UAH and RSS. Common 1981 – 2010 baseline.
Now, look at the 10 year mean:
UAH and RSS. Common 1981 – 2010 baseline; 10 year mean.
The exaggerated slope shows the decade-on-decade warming very clearly. If one does not accept the known physical properties of CO2 as an absorber and re-radiator of LW, then an alternative and demonstrable forcing needs to be found to explain this. None has been, which rather re-enforces the CO2 hypothesis.
Harry Dale Huffman
No, it isn't. Please see both graphs linked from my previous comment (which crossed with yours).
Interesting that the only period where temperature change matched AGW theory (1978 to 1998) was just long enough to exceed this limit. (yes, even IPCC acknowledges that early 20th C warming 1910 to 1945 can explained by natural effects.
Hi Philip
Other evidence comes from the comparison of the natural and anthropogenic radiative forcings" which include observational and experimental contraints as well as model estimates.
NB This does not include other anthropogenic forcings such as land cover change affecting the ratio of sensible to latent heat flux, but it currently appears that such forcings are much more important for regional climate over land than global. Some of my IPCC colleagues would disagree with my use of "forcing" in this context, but that's a somewhat technical issue.
I am open-minded about cosmic rays being a natural external forcing, but current evidence is that this is small. The recent Kirkby paper does not, as far I can see, challenge this situation - I'm still waiting for a response from Jasper Kirkby putting me right on this.
BBD:
No physicist would deny that CO2 absorbs and emits IR. That statement of yours is totally irrelevant. There are numerous explanations for the warming and cooling of the atmosphere that have occurred on various timescales since the world first had an atmosphere 4.5billion years ago. the recent warming is no different from warmings that have occurrred in the past (if one believes the data).
You have to explain why CO2 is the only possible explanation now, when others were responsible in the past.
I do continue to get the impression, that because we can't explain it by natural forcings, then therefore AGW theoriesmust be correct.. rather than go out and attempt to test proof AGW theories are correct.
Which might be feasible, if there weren't the acnowledgement, that so many natural factors are unknown or uncertain. and levels of certatinty are unsubstatiated, ie ref IAC report into IPCC.
Geronimo, That CAGW thingy is always just over the rainbow!
MarcH
You're confusing CAGW with AGW
Santer et al only discuss an issue relating to evidence of anthropogenic influence - they say nothing about impacts, catastrophic or otherwise.
Disingenous About what we should expect.
Since Christy et al used 30 years of data in , does this mean that Santer's paper does not invalidate this study? N.B I am a layman and apologise if this is a silly question.
Oops. Well,the link does work, but I want to try again: What Do Observational Datasets Say about Modeled Tropospheric Temperature Trends since 1979?
Philip Bratby
No. As I said earlier, what is required is evidence for a non-CO2 forcing sufficient to explain the modern warming. Nothing has so far been found. This leaves us with the rigorously tested and widely accepted radiative transfer equations which demonstrate the mechanism by which CO2 warms the atmosphere.
If you want to dismiss the role of increased atmospheric CO2 in modern warming, you have to:
- explain how and why the RTEs are in error
- provide evidence for an alternative forcing sufficient to explain recent warming
It used to be 13 years.
What are the odds on it being 18 years next time around?
Don't be so stupid. In order to debunk one theory, you simply have to show that it doesn't fit with the empirical data. You don't have to propose and validate an alternative theory.
Breathe of Fresh Air (at 9:38 AM) made a good observation : "Sorry but the steepness of the temp increase from the early 70's is the same as the previous 30 year temp increase in the 20 C before 1945, so what is so different between the 2 increases and why is the second CO2 and the first not CO2."
How does CAGW theory explain this?
BBD - "This leaves us with the rigorously tested and widely accepted radiative transfer equations which demonstrate the mechanism by which CO2 warms the atmosphere. "
An interesting take on empirically tested and trusted use of RTE and their implications for CO2 impacts is available here:
http://johneggert.wordpress.com/2010/09/26/the-path-length-approximation/
Depsite looking I've not seen a bottomed out rebuttal.
I find this approach taken in this extraordinary for two reasons:
First, if there is noise in data and one wishes to establish if the mean has changed, there are some fairly robust statistical techniques to do so that depend on the underlying data.
The second reason is that the climate models are all generating reasonably high frequency noise (in climate timescales), or "variability". A cynic might say that that this is due to numerical instabilities in the models themselves. Until the source of this noise in the models is established and shown to mimic real world processes, I can see no merit in observing the outputs of climate models to establish if the real temperature has in fact risen.
"Over the years, Santer et al have developed a reputation for making serial mistakes that other scientists have been forced to uncover."
I would say that is fair comment.
Sorry Bish - just remembered your request!
"Please keep comments to the subject matter of the paper."
Will you be running the blog in 2028?! :-)
The Santer and team paper uses the same misleading trick as Easterling and Wehner did.
Yes there have been periods of 10 years in the recent past when there was no warming.
But these were due to the influence of the volcanic eruptions of El Chichon (1982) and Pinatubo (1991). There is no equivalent volcanic eruption to explain the current lack of warming.
BBD: "The exaggerated slope shows the decade-on-decade warming very clearly. If one does not accept the known physical properties of CO2 as an absorber and re-radiator of LW, then an alternative and demonstrable forcing needs to be found to explain this. None has been, which rather re-enforces the CO2 hypothesis."
This may be a difference between engineers and scientists, I don't know, but in engineering the fact that something can't be explained, would lead to an investigation to try to explain it, not to an assumption that other things may be the cause or are indeed the cause. In an engineering environment CO2 would be the prime suspect in this case, not the assumed cause. As I say it may be that the different disciplines approach things differently because of the outcomes of a mistake, so science can afford to make assumptions and wait to see if they're correct while engineers cannot.
Normally scientists assuming something will have no effect, because their assumptions cannot pass into real action until they have been eliminated/proved correct, what we have here is an odd confluence of events, the world is getting warmer/green movements trying to impose their views on the world/scientists getting money to prove AGW/activist scientists. This confluence has acted to persuade politicians that something must be done to reduce CO2 emissions. So a mish mash of solutions have been put in place, taxing the use of energy which is putting costs into our everyday lives, and may well cause massive problems, both industrially and domestically. Replacing fossil fuel generated enery sources with something called "renewable energy", which sound like perpetual motion, but doesn't include nuclear. The prospects of this happening in any reasonable timescale are remote to impossible. While we're doing all this we conveniently forget that the big belchers aren't stopping at all, in fact they're increasing their output of CO2, so our mish mash of solutions won't solve anything anyway.
Meanwhile all this is on the back of assertions by people that they can't find natural forcings to account for some, I'll repeat that, some, of the recent warming. Back to the first quote, as an engineer the first thing I'd ask is, "Are we sure we know all the natural forcings? Could there be some out there we don't know about?"
Hmmm. Seventeen years, eh?
I wonder if Santer will call BS on the next person who claims a drought in Texas or a tropical storm in NY is proof of AGW?
Or do you think he wants to have it both ways?
Has anyone actually seen the paper? It says "in press", and doesn't have the "full text" link that JGR atmospheres usually has when the paper is available. I don't have an AGU login so I don't know if AGU members can see the paper.
I'm interested in the paper, particularly on how they deal with the criticisms published by Dr Koutsoyiannis on the problems with the meaningless "signal" and "noise" paradigm for climate. But until I can see the article itself, there doesn't seem to be much to discuss.