Continuation of the older threads. Please scan those (even briefly) to see whether your point has already been dealt with. Let me know if there is something worth pulling from the comments to the main post.
In the meantime, read about why peer-review is a necessary but not sufficient condition for science to be worth looking at. Also, before you conclude that the emails have any impact on the science, read about the six easy steps that mean that CO2 (and the other greenhouse gases) are indeed likely to be a problem, and think specifically how anything in the emails affect them.
Update: The piece by Peter Kelemen at Columbia in Popular Mechanics is quite sensible, even if I don’t agree in all particulars.
Further update: Nature’s editorial.
Further, further update: Ben Santer’s mail (click on quoted text), the Mike Hulme op-ed, and Kevin Trenberth.
Max von nadcker — As I stated before, we attempt to do science here, not numerology. That means using some statistics; learn some.
In the current context, I assert that “60 year cycles” are a product of your (untrained) eye. With statistics one finds this is just noise.
That would, of course, change if you could find a long enough temperature proxy record to demonstrate such “60 year cycles” with statistical significance. I’ll sae you some trouble; GISP2 temperatures don’t have such “cycles” over the entire course of the Holocene.
Completely Fed Up (1148)
“Your cycles are shibboleths created by your errant analysis”
Whoa! Slow down there.
The observed warming/cooling cycles are real, even if they cannot be fully explained.
The most recent (late 20th century) warming cycle is real, and IPCC has spent a good portion of 1,000 pages referring to it and explaining it, attributing it partly to increased atmospheric levels of GHGs. Do you deny its existence?
The early 20th century warming cycle is mentioned only briefly, and there is more uncertainty about its explanation. Do you deny its existence?
The mid-century cooling cyle is also mentioned quite briefly, with a tentative rationalization rather than a real firm explanation. Do you deny its existence?
Earlier warming and cooling periods in the late 19th century and turn of the century are not mentioned specifically, but the record shows they did exist, with all the doubts that exist about the accuracy of 19th century temperature records. Do you deny the existence of these warming and cooling cycles?
Don’t be a “climate denier”, CFU.
Max
To manacker:
There is no cyclic behavior in the data. Get over yourself.
To everybody else:
Manacker is both foolish and intransigent. It’s time to simply ignore him.
David B. Benson
Sorry. It is not my “untrained eye” that is an issue here.
It is your inability (or unwillingness) to see the fairly evident cyclical nature of the observed global temperature record.
Max
Max says, “The mid-century cooling cyle is also mentioned quite briefly, with a tentative rationalization rather than a real firm explanation. Do you deny its existence?”
Uh, Max, the aerosol-induced cooling of the post-war period has been modelled and the aerosol mechanism has been found to be an adequate explanation. Tamino has looked at the warming in the 1930s and found that much of it could be attributed to a volcanic lull, somewhat increased insolation and a few other causes. Now, unless your theory is that somehow all of these diverse forcings are somehow correlated according to some great cosmic sine wave, I think you’ll have a hard time publishing. But go ahead and try. We’ll wait.
Max von Anacker — When it comes to claims of seeing “cycles” I am, partly through training and partly through experience, deeply skeptical. Through the portion obtained by training as an electrical engineer, I think I know an actual cycle when I see (enough samples of) one. For example, on this side of the pond we have 60 Hz electricity and I believe on your side 50 Hz electricity; in both cases those come in actual cycles.
I know that many use the word “cycle” rather more loosely than that, but here we attempt to do science; most physicists will agree with the electricals about periodic phenomena, actual cycles as the term is used in science. Such phenomena are rare in climatology and meteorlogy beyond the obvious annual cycle. The only one I am competely confident of is a 3.75 year cycle found by at least four different analyses of at least thre different time series from two different oceans. Researches have gone out and measured the cause. Another which only shows up in one of the four analyses has a 2 year period; that alone is not enough to convince me this is more than an artifact of the data processing.
Somewhat less obviously “cyclic” are the pseudoperiocic phenomena such as the sunspot “cycle”. These offer less predictability as the slow launching of the current sunspot “cycle” demonstrates.
Still less obviously “cyclic” are the quasi-periodic oscillations (QPO). Possibly ENSO is sufficiently regular to be placed in this category. I’m not sure about other of the ocean oscillations, but
“Is the North Atlantic Oscillation just a pink noise?”
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TVG-4816VTJ-4&_user=7810834&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1134325391&_rerunOrigin=google&_acct=C000011439&_version=1&_urlVersion=0&_userid=7810834&md5=d4595f4812e7ff4a11bb960b2f604bab
while there seem to be some minor errors, suggestss that NAO is not even a QPO.
Finally, there are just “oscillations” about which so little is known that one cannot (yet) even say these are QPOs. See the illustration of (1/f^1.5) noise towards the end of “1/f noise: a pedagogical review”
http://arxiv.org/abs/physics/0204033
(Figure 25). Note how easily one sees “cycles” in this data which is just generated by some random process. That is what I mean by “untrained eye”.
Now what I see in HadCRUTv3 or GISTEMP or NCDC or JMA is a linear upward trend; a linear trend will do but I also directed you to BPL’s nice comparison of GISTEMP with ln(CO2); that will do even a bit better, methinks. Now look at the resdiuals, the wobbles above and below the linear trend line. That looks to me to me autocorrelated “noise” and there are statistical tests for that; either follow Tamino’s most clear expositions (I directed you to one) or strike out on your own via web trawling on Box/Jenkins or even just autocorrelation.
Starting anyway by the 1930s, some scientists became deeply disatisfied with the rigor of the discourse over just what data implied and so started modern day notions of statistics. I didn’t need any of it until recently and have been running to catch up to the work down in the 1970s. There is of course much done later, but I’m not that far along yet.
So if you see “cycles” you will have to define precisely what you are taking about and then demonstrate the degree of statistical significance to be attached to what is actually found in the data. I strongly urge you to avoid the word “cycle” for whatever you think you have found; coin a new term, please. But since the instrumental record is so short compared to whatever you think you are seeing, please do check whether or not a (1/f^a) random process, with the value of the exponent “a” between 1 and 1.5 won’t do just as well. I think that will be the case for the residuals from the (removed) linear trend; congraduations, what you are seeing is just random!
Completely Fed Up wrote in 1147:
Actually one of the passages I quoted in 1142 specifically mentioned lasers.
Quoting from the AMS Glossary of Meteorology entry for local thermodynamic equilibrium, it states:
Apparently lasers are an instance of where matter emits radiation based upon something other than just the intrinsic properties of the laser itself and its temperature, e.g., the radiation that is being absorbed. Therefore LTE conditions no longer apply.
Nevertheless, non-local thermodynamic equilibrium conditions (non-LTE) conditions may continue to apply.
The following are some papers that I have run into regarding non-local thermodynamic equilibrium conditions…
Non-LTE diagnostics of the infrared observations of the planetary atmosphere
Oleg Goussev an der Fakultat für Physik der Ludwig–Maximilians–Universitat
Munchen 2002
http://edoc.ub.uni-muenchen.de/archive/00001056/01/Goussev_Oleg.pdf
User’s Manual for SHARC-3, Strategic High-Altitude Radiance Code.
Corporate Author: PHILLIPS LAB HANSCOM AFB MA
Personal Author(s): Sharma, R. D. | Gruninger, J. H. | Sundberg, R. L. | Bernstein, L. S. | Robertson, D. C.
Organization Type: F – AIR FORCE
Report Date: 21 MAY 1996
Report Number(s): PL-TR-96-2104-ERP-NO-1193 (PLTR962104ERPNO1193)
http://handle.dtic.mil/100.2/ADA313523
One interesting result…
If you look at “Figure 2. Calculated Vibrational Temperatures for C02 States for a Solar Zenith Angle of 82°”
of …
D-A275 207
SHARC, A Model for Calculating Atmospheric and Infrared Radiation Under Non-Equilibrium Conditions
January 24, 1994
http://stinet.dtic.mil/cgi-bin/GetTRDoc?AD=ADA275207&Location=U2&doc=GetTRDoc.pdf
… you will see how all vibrational states of 4.3μm have the same brightness temperature — that energy is equally partitioned among each state of excitation — until about 40 km. The equipartion of energy is what we expect — under local thermodynamic equilibrium conditions. But at 40 km collisions are becoming infrequent enough that energy is no longer equally distributed among the different vibrational states. As such it is valid to claim that carbon dioxide no longer has a well-defined temperature starting at that altitude.
There will be the temperature associated with the translational kinetic energy — which is what we would classically refer to as “temperature,” but this will no longer be equal to the vibrational temperatures associated with the different quantized states of molecular excitation as they are no longer equal. Under the local thermodynamic conditions that apply below 40 km collisions are frequent enough that what we would classically define as temperature and the vibrational temperatures associated with each of the states. However, typically one has to go to higher altitudes (~70 km) before the different temperatures associated with quantized states of excitation begin to diverge.
tamino (1144), are you saying the data shown in #1143 is not cyclical?
I think Gavin addressed this situation best.
…any random application of a low-frequency smooth and trends through the residuals [of a regression] could be used to get anything you want. This kind of ‘analysis’ is completely arbitrary and proves nothing to anybody…. the cycles you find [in the residuals of a linear regression] are completely determined by what you arbitrarily defined as the trend. But, and here’s the problem, the forced component of climate change isn’t forced to follow any arbitrary smoothing function (linear or otherwise). To declare that your particular decomposition is a ‘fact’ is on a par with declaring that the Cydonian hills contain a face. It is a complete artefact. Is their multi-decadal internal variability? sure. But residuals from linear trends do not define it.
The real problem is as indicated by 1151 and 1152: some combination of statistical illiteracy and willful intransigence. Reading over the past few days, I’m leaning toward the latter.
This brings up an interesting issue in scientific and technical communication. Gavin and others use technical terminology, e.g. significant, residual, variation, in (usually) a precise manner. These same terms are used by others in an imprecise manner, sometimes in an attempt to sound more technically savvy than they are, but sometimes innocently.
In any case, here’s one vote for RC to close this thread. I think there’s enough food for thought here and everyone’s energy would be better spent in other places.
Happy holiday,
et al, just curious: is a sine wave cyclical? Or are the ups and downs simply noise in a near perfect linear regression trend?
Ray (1155), (it’s not my business sticking up for max, but this is a bit interesting…): I don’t recall max explaining the cyclical variations, just pointing out that they seem to be there. I don’t know if, like tamino et al, you assert also that they don’t even exist, but why are you explaining the cyclical variations that tamino says are not there?
Rod B
You are 100% right.
I have postulated no explanation for the observed warming cooling cycles.
I have simply pointed out that they exist (which is fairly obvious).
The response has been (a) that they do not exist at all, (b) that there is no explanation for their existence, (c) that they simply constitute background noise, etc.
These responses all either deny something that is obvious or attempt to rationalize it away, because it cannot be explained.
The fact that the Met Office has attributed the current cooling (start of a longer multi-decadal cycle?) to natural forcing factors opens the question why these earlier cycles could not also have been caused by the same natural forcing factors.
It appears, from what I have seen, that you have the same question, which the others have, so far, been unable to answer.
Let’s see if they can do any better.
Have a happy holiday.
Max
1157, Tim I agree with your post but again it’s LTE. If you’re not under LTE, those statements do not automatically hold.
Max:
Since there’s no continuous trend, there has to be variations. Variations mean up and downs. up and downs aren’t cycles.
Rod B., It is very easy to disappear down a rabbit hole looking for periodic and quasi-periodic oscillations. Usually, they are spruious artifacts of the dataset for several reasons.
First and most important, in order to have periodic or quasi-periodic oscillation, you need a forcing with a period (or quasi-period) equal to that you propose. For such a forcing to be as dominant as Max et al. are claiming, it would have to be a very strong forcing. No such forcing has even been mooted.
Second, to identify a periodic oscillation–especially against a noisy background–you need several full periods of oscillation.
Third, remember the Fourier Series–you can fit any data if you take enough oscillatory terms. For this reason you need to understand the physics to minimize the time you spend lost in the weeds. Scafetta and West fall victim to the same malady, and they are not dumb.
Most important, though, you have to be willing to believe what the evidence is telling your, and that is really where Max, JBob, Scafetta and West and all the Fun-with-Fourier crowd get lost.
Thank you for the stratospheric cooling reference, 1039.
The charts seem to confirm the absence of stratospheric cooling which I posted at 1031.
If you look at the Hadley Centre frequently used radio-sonde charts you will see that there has been no troposheric warming at any level from 1958 to 1978, and no stratospheric cooling for the past 14 years.
If you download and regress the data you will find that here was no lower tropospheric warming from 1958 to 1991, a period of 33 years.
So which of these two statements best reflects the data :
The fundamental AGW signature is the cooling of the lower stratosphere and the simultaneous warming of the troposphere.
OR
The fundamental AGW signature is the cooling of the lower stratosphere (which has been masked by changes in the ozone layer in recent years), and the warming of the upper troposphere which began when stratospheric cooling ceased.
[Response: Neither (as you well know). – gavin]
Re: #1158 (Rod B)
Is it cyclical? Not.
I have read some of these leaked e-mails, presumably the potentially most damaging ones (since those are likely to be the ones that have been discussed online), and I don’t really see any evidence of scientific fraud here, nor any evidence that the peer-review process has been tampered with. The fact that climate scientists tried to stop a paper from being published doesn’t mean that the peer-review process has been compromised, that depends entirely on the quality of the paper. If the paper wasn’t up to par, it is actually evidence that the peer-review process is working.
The only thing that is still unclear to me is the issue of what data is publically avaiable, how long it has been available, and whether any data has beeen deleted? From what I understand, most of the climate research data is publically available today (there are several links on realclimate.org), along with source code. Apparently, there is some data that has not been released due to legal obligations, i.e. agreements that the data would not be made available to any third party.
So my first question: Is it the case that the data that has been argued over in these e-mails, is exclusively data that could not be released for legal reasons? Or has also other data been asked for and not released?
And 2) There is talk on the internet about raw data having been deleted. Couyld you please clarify exactly what that is about?
Thank you!
“just pointing out that they seem to be there.”
Might as well say there seems to be the outline of a section of the alps there.
In fact, if you’re not *allowed* to say a paper shouldn’t be printed, how can the peer review process even work?
If you can’t censure editors how can editorial integrity be expected to survive?
If you can’t say that something is not worthy, how can you judge reliable sources?
“There is talk on the internet about raw data having been deleted.”
If I get some data from another company for a specified purpose, once that data has been used, I MUST delete my copy else I breech copyrights.
This doesn’t delete the original data from the owner.
If *they* delete their data, why blame me?
PS anyone got an idea how many times that question has been asked on multiple topics on RC alone?
That figure (if someone has the list of links, that would be a good post, eric/Gavin/etc) were printed, then maybe someone who is genuinely curious will know why they’re being ignored.
Ray, I didn’t mean to be totally critical. Your explanation does describe an answer for the short-term poor correlation based on physics, at least for part of the cyclical period. It also might imply a plausible answer to the cyclocity (is that a word? It should be!), which is maybe it’s just a fluke or coincidence. I don’t know if that’s totally satisfactory but it does put the discussion back in the substance of the science. Up to now the response to Max has been essentially “I CAN’T HEAR YOU!!”
Rod B., Dave Benson and Timothy have both engaged Max’s arguments and shown they are bunk. You might also want to see Tamino’s latest post–it pretty much puts paid to the whole “60-year-cycle” myth. The point is that it is very easy to hallucinate dependencies–especially cyclical ones–if you don’t have a solid physical rationale for why the system should oscillate.
Re mad max’s comments:
Definition of “cycle”
11. (Physics / General Physics) Physics a continuous change or a sequence of changes in the state of a system that leads to the restoration of the system to its original state after a finite period of time. (http://www.thefreedictionary.com/cycle)
As anyone can see, the “cycles” seen my mad max do not fit this definition since they do not return to baseline but show an ever increasing slope which, of course, is due to AGW.
Rod, pattern recognition.
We’re strongly biased to seeing patterns whether or not they exist.
This is studied and you know how to look it up.
People pushing their wishful thinking also know this well, and will tell you what you see must be real; they discourage statistical analysis.
Arthur Conan Doyle wrote:
“When you have eliminated the impossible, whatever remains, however improbable, must be the truth.” And he took this picture, and believed it.
http://www.lhup.edu/~dsimanek/fairies/cottin2c.jpg
You can do better.
The image I linked is from:
http://www.lhup.edu/~dsimanek/doyle.htm
And lest anyone misunderstand, I wrote “He took this picture” — he accepted it, believed it real, was taken _by_ it. So did many others at the time. It’s cautionary.
Remember, statistics is a very new area of mathematics, and still a contentious one. It’s the best tool we have, and it’s still being improved.
Oops, misplaced a followup in the related thread.
This belongs here: the image above is from
http://www.lhup.edu/~dsimanek/doyle.htm
By “he took” I mean he accepted and believed, as did many others; he ‘was taken by’ this picture.
When you begin by eliminating what you cannot believe, what remains that you find credible may be your own ideas that you imagine are the real world.
Jaber Aberburg says: 22 December 2009 at 9:43 AM
“And 2) There is talk on the internet about raw data having been deleted. Could you please clarify exactly what that is about?”
When all other possibilities have been explored and discarded, “the data that would prove me right was deleted” is a final, last ditch available defense of an untenable position. For purely rhetorical purposes, it’s a sealed bunker to hide in once all other weapons have been exhausted.
Regardless of the situation with the data in question, whatever its condition, there is a cornucopia of other data that coincides. The deletion bunker has a very limited horizon of utility, is really only useful if one is prepared to focus on this increasingly tiny minority of information and ignore everything else. That is, unless one is prepared to move on to philosophy of science arguments about group-think, etc.
The trouble with the philosophical approach is that it still does not explain actual observations in a satisfactory way. The observations stand, whatever the conclusions drawn from those observations may be.
Ray Ladbury
David B. Benson
Tamino
Timothy Chase
Completely Fed Up
The exchange on the observed warming/cooling cycles has gotten repetitive (and is OT in any case).
Some of you have denied something that is apparent from the temperature record since it started in 1850, namely that it has warmed and cooled in multi-decadal cycles of around 55-60 years each; others have opined that these cycles are just background noise, or that they have been explained by the models.
IPCC has cited three of these half-cycles, which were observed in the 20th century. It has given principal attention to the late 20th-century warming cycle, which it described as starting around 1976.
Those two half-cycles, which were observed in the 19th century, have not gotten much attention.
It could well be that these cycles can be at least partly attributed to the same “natural variability” (a.k.a. natural forcing) that has been cited by the Met Office as the cause for the observed cooling since the end of 2000.
Of course, if one denies that the observed record shows cooling over the past 9 years, then one can just as well deny all of the observed cycles (or just call them “noise”).
But that does not make them go away.
We are not going to convince each other of our different standpoints on whether or not temperature fluctuated in multi-decadal trends or nor, so we should stop this discussion and let others make up their minds based on the record as it stands.
Max
Ian Forrester
Definition of “cycle”:
There is no mention here of returning to the same “baseline”.
There can be (as there was in the case of global temperature) an observed underlying upward trend.
Or, as in the case of the sunspot example cited in the definition, it can return to a different point in a more random way (increasing steadily over the 20th century until the 1960s, then leveling off until the 1990s, before decreasing again).
But, regardless of the point of return, it is a cycle.
Max
Mac von Anacker — Tamino shows why you are wrong about cycles in
http://tamino.wordpress.com/2009/12/22/cyclical-not/
and about recent temperatures in
http://tamino.wordpress.com/2009/12/15/how-long/
#1179
To convince yourself that decadal temperature fluctuations can be generated purely randomly, try this little calculation with Excel (with the data analysis package)or any other spreadsheet with the a random number generation capability: Make up a dataset with random Gaussian noise superimposed on a linear trend and plot the result. I did this as a classroom demonstration and was amazed to see just how closely certain sections of the graph resembled the actual 20th century temperature graph: There were some multi-decadal trends that were flat or had a slightly downward trend and others that had an upward trend much greater than the one I had used in the construction. (Of course, the average trend was equal to the one that I had supplied in constructing the graph.)This is a fact that has long been known to statisticians: purely random noise can give rise to what appear to be “cycles”. This is why scientists don’t get particularly excited about what happens to the global temperature over short periods, e.g., the past ten years.
Somebody apparently hoping to have the last word:
“IPCC has cited three of these half-cycles, which were observed in the 20th century. It has given principal attention to the late 20th-century warming cycle, which it described as starting around 1976.”
Lest the casual observer become infected by sloppy terminology leading to erroneous conclusions or beliefs, IPCC itself does not cite any such cycles. There is no mention of long-term cyclical variations of temperature since 1850 in the latest IPCC report, either in the synthesis report or that of the physical sciences working group. There are temperature records on display in both reports showing variations over the period since 1850, but these are not identified or cited in the report as cyclic in nature.
The only mention of temperature cycles in either report are those of a diurnal or annual nature, plus the “weekend effect” on certain measurement stations.
Yeah, what’s his name uses the word “cited” like he uses the word “trend” — Lewis Carroll, you know, described this quite well. He masters the words.
“Rogue Scientist Has Own Scientific Method”
http://www.theonion.com/content/node/49180
Completely Fed Up wrote in 1163:
Below altitudes of 40 km, LTE is the rule, not the exception.
Please see:
Lasers and fireflies are exceptions, but climatology generally doesn’t have to worry about such things. Nevertheless, it is my understanding that recent climate models have been using SHARC-3(or its descendants) and the non-LTE calculations. They are incorporating higher altitudes, so I guess this makes sense.
Hank (175), Of course “We’re strongly biased to seeing patterns whether or not they exist.” But that doesn’t mean that every pattern we think we observe is wrong or maybe doesn’t even exist! I’m sorry, but to repeat, anyone who looks at those smoothed temperature charts and doesn’t see an up and down wiggle in some sort of repeating scheme needs his eyesight and perceptibility checked quickly.
Hank (176) says, “…statistics is a very new area of mathematics, and still a contentious one. It’s the best tool we have, and it’s still being improved.”
I agree with that fully. However one should not forget the key word “tool.” It is a tool to help us see the physics; it is not the physics.
This is a delayed post. My browser ate the first one.
David B. Benson (1156), I think your confusing cyclical (defined as a group of events which happen in a particular order, one following the other, and which are often repeated) with meaningful. You say you know few climate cycles, then go on to describe a bunch. I think the overall problem I have (with what otherwise is an astute post) stems from using statistics as physics drivers — without a lot of deliberate conscience thought — rather than as man-made constructs that helps us look at and analyze data that physical processes provide. The “cycles” under discussion are interesting because 1) they demand a physical hypothesis as to why, e.g., temperature would go down in the face of increasing CO2 (and some have been proffered), and 2) the cyclical nature looks interesting and it would be helpful to know if it is meaningful or not, and maybe what causes it. The key in those questions is “meaningful” in the physics sense, not in the sense of our own construct of linear regression, residuals, and such.
There can be cyclical from random generations; there can be cyclical riding on some long term trend. (What does the capacitor’s output of a rectified AC source feeding an RC circuit look like? Is it cyclical? Does it follow an upward trend? If there are both a series and a parallel resistor?) Relying on a precise definition of “cycle” or on a precise interpretation of linear regression and such simply avoids the question and doesn’t get to the answer.
Ray (1173), your still adamantly confusing observation with significance. Max said he has observed cycles in the temperature record. Frankly it doesn’t take a rocket scientist [not getting personal here ;-) ] to look at the graph and see that it is surely going up and down in some repeated fashion. You and tamino ought to be saying you know of no meaningful physical substance behind it. Saying it is not even there makes you sound, pardon, stupid.
@Rod B.
I could not have put it more eloquently. I take it that you have a little background in engineering (real world stuff…).
I was quite put off with this entire thread, until I came upon your post. Thank you.
Timothy Chase @ 859:
I’ve been posting here for long enough, and for long enough before the present solar cycle, about the effects of a grand solar minimum on “weather”.
Every time anyone utters “Galactic Cosmic Rays” there’s a giant storm of “No! Disproven! Bogus!”.
Well, I’ve reached a point now that we’re just about done with 2009 and it’s shaping up to be one of the quietest solar years in decades, that I really wish climate scientists would figure out why the hell we’ve not broken a “hottest year on record” in a while and why the sun seems to have gone to sleep — and they “coincidentally” seem to have happened at about the same time.
And while I was initially annoyed by the “CRU Hack” (I’m a computer security geek by trade, all “hacks” are annoying), I’m starting to think it was exactly what was needed to draw attention to climate science.
Furry Catherder, See this analysis by Tamino:
http://tamino.wordpress.com/2009/06/26/breaking-records/
Both 1998 and 2005 were big El Nino years, and I am sure you understand that looking at only one year is misleading. The oughts were the warmest decade on record. And yes, the EAU hack has brought in a lot more folks to RC, and that is good. Now we’ll find out if any of them have learning curves with a positive slope.
Furrycatherder:
If you still think GCRs are so important, please explain the lack of climate response to the Laschamp excursion, which saw a HUGE amount of GCRs, many times more than today, hit the earth.
Rod B., The human brain has a very sensitive threshold for spotting patterns. Now certainly, you can take past data that goes up and down and come up with a simple oscillatory theory that explains it. Unfortunately, the goal of science is not really simple explanation, but rather prediction of future behavior. I can always, under all circumstances come up with a 3rd degree polynomial that explains (fits) 4 data points. However, that fit will give me zero predictive ability unless there is no noise in the data.
What we need are tools for telling us whether the pattern our eyes and cerebral cortices spot has an underlying basis in the data–that is, whether the pattern is likely to repeat or give us insight into future behavior. If we cannot do that, we are merely playing games with numbers, no more profitable than Soduku. One tool we can use in this search for REAL PATTERNS is physics. Is there a physical mechanism that would cause the system to behave like this? We know such a mechanism would have to oscillate with the same frequency as the pattern we are positing, and no such forcing presents itself. Strike one.
The other tools we can use in our quest are statistical. These tools are essential if we are not to let our pattern recognition fool us. Unfortunately, we know that for a noisy system like climate, we would need several repetitions of a particular cycle to assess whether it was really there. There simply is no statistically significant evidence for the “60-year cycle”. Strike 2.
And finally, we know from Fourier series that on a finite interval, if we take enough sinusoidal terms we can approximate the data–except at the edges. As Tamino’s post shows, this is where the cycle breaks down. Strike three.
Do me a favor Rod. Graph the following series of points:
1-2
2-7
3-1
4-8
5-2
6-8
7-1
8-8
9-2
10-8
11-4
Do you see an oscillatory pattern? What do you think could be driving it?
Would it help if I told you that the ordinate (y-axis) points are the digits in e, the base of the Napierian logarithms. This number is known to be transcendental–no rhyme or reason to its digits. This is why mere seeing should not translate to believing.
Ray (1194), for the most part that is exactly what I have been saying. (Maybe Max, too, but he has to determine that.) However, I think there are TWO basic areas to explore. You are talking of the numerical and statistical analysis (linear regression, Fourier series, maybe wavelets, etc) and you (and others) are correct that this is the best methodology to assess predictability and significance of trends, if any. But another question (if initially it looks interesting from a science viewpoint) is, not predictability, but why is it doing what it is doing at the time from a physics/science position. None of the mathematical analyses provide insight into this question. The specifics under discussion here is (or IMO ought to be) scientifically interesting because 1) the temperature is going the wrong way vis-à-vis CO2 concentration in the interval of question and 2) it seems to have some level of periodicity. Maybe it’s the atypical situation where a scientist says, “That’s odd.”
Simply shoving it under the rug because on the surface it looks inconvenient [like what you guys accuse us skeptics of doing all the time ;-) ] doesn’t count.
Rod, I’m just curious. Why is it that you and Max and Joe-Bob and the other fun with Fourier guys just love to jump down rabbitholes after phenomena with virtually no statistical significance and yet you feel free to ignore a warming trend that is significant at the 1% level or better? Strikes me as a rather odd way to spend your time. No one is denying that the temperature rises and falls a couple of times, but until you have a statistically significant signal to analyze, there’s nothing to deny.
Rod, have you heard of self-organized criticality? It’s one of the ways you can get behavior that looks oscillatory out of a system that isn’t being driven by a periodic function. SOC applies to phenomena like earthquakes and solar flares and I think lightning strikes. The idea is that the system is storing energy and at some point it relaxes and gives up that energy. It takes a certain amount of energy to activate the relaxation mechanism (e.g. strike-slip motion of the fault, the solar flare, the lightning strike) and the energy TENDS TO accumulate at roughly the same pace, so it can look as if the system is periodic. It isn’t. Just when you think you can predict something, the dynamics changes slightly and there goes your oscillation.
I’m not saying I think anything like that is going on here. Rather, in this case, I think we have an artifact–a coincidence of the type that happens in systems where you have red-pink noise. The thing that makes me think this is that the system fails to match up with predicted behavior at the boundaries. That indicates that all we’re doing is coming up with a Fourier series for the noise–and that isn’t particularly interesting.
So, let’s review:
Temperature record of the late 20th and early 21st century matching up with a linear trend–very significant.
A couple of oscillations that SORT OF have the same period in a sytem with lots of low-frequency noise and correlation–not significant.
Any questions?
Perhaps the swings in question are regularly periodic but one cannot really say without returning to look again long after we’re all dead. Failing being able to do that, somebody’s going to need the competence to produce a robust description of a plausible mechanism that could drive such a signal in order to gain any real traction with the idea.
In the meantime, the fellow that wants us to divert attention to the putative signal has also made the claim that AGW is “all a hoax”, he’s on record as having problems with most if not all evidence supporting the notion of anthropogenic climate change, so he’s one of the very worst persons available to defend what he thinks he sees. “Crying wolf” is the phrase we so often hear. Man bites dog, etc.
“Delay is the deadliest form of denial.” That’s the business they’re doing.
Rod B (1189) — No such confusion. I might have done better to avoid the word “cycle” do to rather sloppy usage and instead stick with
(1) periodic
(2) psuedoperiodic
(3) quasi-periodic oscillation
(4) oscillations, i.e. just wobbles
For weather/climate , (1) is illustrated by the annual period and a 3.75 year period; both are highly predictable. The sunspot variations illustrate (2); not so predictable, but somewhat. Probably ENSO illustrates (3); little predicatability. I linked to a paper suggestiung that NAO is such (4), pink noise; no predictability there beyond statistical properties.
[I hope this is not a repeat. My Avant browser has developed a mind of its own.]
Ray (1196), why do you offer (just) a hypothesis of an answer to a question that has no interest for you?
Some scientists might say, “that’s odd and interesting. I wonder why that is” Others might not. It’s a personal choice and some might not find it interesting. But kinda getting back to max’s original point, saying that non-interesting phenomenon isn’t even there is perplexing.
David B. Benson (199), that sounds basically right. The question could be: how do you know the sunspots are a little predictably periodic if one didn’t initially see some pattern — maybe short-term at the time — and said ‘that’s interesting; I think I’ll look into it.’ And then looked into the physics first: what are the spots, really? why do they seem to come and go? If they put out more energy why are they darker? etc? At that juncture linear regression, fourier series, wavelets are not in the picture.
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As a layman with some knowledge here, I would bet (but not give odds) that nothing of physical significance would be found. Though I might lose the bet. It does seem to me that a climatologist developing AGW would be (or ought to be) very interested in a period where temperatures went down while CO2 continued its increase when, on the surface, that ain’t how it is supposed to work. Instead it seems inconvenient: “Send ’em the trend letter and put this thing to bed and move on!”