We are a little late to the party, but it is worth adding a few words now that our favourite amateur contrarian is at it again. As many already know, the Forum on Physics and Society (an un-peer-reviewed newsletter published by the otherwise quite sensible American Physical Society), rather surprisingly published a new paper by Monckton that tries again to show using rigorous arithmetic that IPCC is all wrong and that climate sensitivity is negligible. His latest sally, like his previous attempt, is full of the usual obfuscating sleight of hand, but to save people the time in working it out themselves, here are a few highlights.
As Deltoid quickly noticed the most egregious error is a completely arbitrary reduction (by 66%) of the radiative forcing due to CO2. He amusingly justifies this with reference to tropical troposphere temperatures – neglecting of course that temperatures change in response to forcing and are not the forcing itself. And of course, he ignores the evidence that the temperature changes are in fact rather uncertain, and may well be much more in accord with the models than he thinks.
But back to his main error: Forcing due to CO2 can be calculated very accurately using line-by-line radiative transfer codes (see Myhre et al 2001; Collins et al 2006). It is normally done for a few standard atmospheric profiles and those results weighted to produce a global mean estimate of 3.7 W/m2 – given the variations in atmospheric composition (clouds, water vapour etc.) uncertainties are about 10% (or 0.4 W/m2) (the spatial pattern can be seen here). There is no way that it is appropriate to arbitrarily divide it by three.
There is a good analogy to gas mileage. The gallon of gasoline is equivalent to the forcing, the miles you can go on a gallon is the response (i.e. temperature), and thus the miles per gallon is analogous to the climate sensitivity. Thinking that forcing should be changed because of your perception of the temperature change is equivalent to deciding after the fact that you only put in third of a gallon because you ran out of gas earlier than you expected. The appropriate response would be to think about the miles per gallon – but you’d need to be sure that you measured the miles travelled accurately (a very big issue for the tropical troposphere).
But Monckton is not satisfied with just a factor of three reduction in sensitivity. So he makes another dodgy claim. Note that Monckton starts off using the IPCC definition of climate sensitivity as the forcing associated with a concentration of 2xCO2 – this is the classical “Charney Sensitivity” and does not include feedbacks associated with carbon cycle, vegetation or ice-sheet change. Think of it this way – if humans raise CO2 levels to 560 ppm from 280 ppm through our emissions, and then as the climate warms the carbon cycle starts adding even more CO2 to the atmosphere, then the final CO2 will be higher and the temperature will end up higher than standard sensitivity would predict, but you are no longer dealing with the sensitivity to 2xCO2. Thus the classical climate sensitivity does not include any carbon cycle feedback term. But Monckton puts one in anyway.
You might ask why he would do this. Why add another positive feedback to the mix when he is aiming to minimise the climate sensitivity? The answer lies in the backwards calculations he makes to derive the feedbacks. At this point, I was going to do a full analysis of that particular calculation – but I was scooped. So instead of repeating the work, I’ll refer you there. The short answer is that by increasing the feedbacks incorrectly, he makes the ‘no-feedback’ temperature smaller (since he is deriving it from the reported climate sensitivities divided by the feedbacks). This reverses the causality since the ‘no-feedback’ value is actually independent of the feedbacks, and is much better constrained.
There are many more errors in his piece – for instance he accuses the IPCC of not defining radiative forcing in the Summary for Policy Makers and not fixing this despite requests. Umm… except that the definition is on the bottom of page 2. He bizarrely compares the net anthropogenic forcing to date with the value due to CO2 alone and then extrapolates that difference to come up with a meaningless ‘total anthropogenic forcings Del F_2xCO2’. His derivations and discussions of the no-feedback sensitivity and feedbacks is extremely opaque (a much better description is given on the first couple of pages of Hansen et al, 1984)). His discussion of the forcings in that paper are wrong (it’s 4.0 W/m2 for 2xCO2 (p135), not 4.8 W/m2), and the no-feedback temperature change is 1.2 (Hansen et al, 1988, p9360), giving k=0.30 C/(W/m2) (not his incorrect 0.260 C/(W/m2) value). Etc… Needless to say, the multiple errors completely undermine the conclusions regarding climate sensitivity.
Generally speaking, these are the kinds of issues that get spotted by peer-reviewers: are the citations correctly interpreted? is the mathematics correct? is the reasoning sound? do the conclusions follow? etc. In this case, there really wouldn’t have been much left, and so it is fair to conclude that Monckton’s piece only saw the light of day because it wasn’t peer-reviewed, not because it was. Claims that the suggested edits from the editor of the newsletter constitute ‘peer-review’ are belied by the editor’s obvious unfamiliarity with the key concepts of forcing and feedback – and the multitude of basic errors still remaining. The even more egregious claims that this paper provides “Mathematical proof that there is no ‘climate crisis’ ” or is “a major, peer-reviewed paper in Physics and Society, a learned journal of the 10,000-strong American Physical Society” are just bunk (though amusing in their chutzpah).
The rational for the FPS publication of this note was to ‘open up the debate’ on climate change. The obvious ineptitude of this contribution underlines quite effectively how little debate there is on the fundamentals if this is the best counter-argument that can be offered.
Congrats on such a well debated site, keep up the good work.
I am an engineer (not a climate scientist) but I have some exopertise in the handling of risk and the analysis of wind, earthquake risk for design of buildings.
It is clear to me that the argument of the last 5 years indicating a down turn is not supportable. You only have to look at the graph to see that the trend is up with no indication of a turn yet. If the graph was a share price, I do not think any share trader would be thinking of selling their shares.
The trend is up and has been substantially for the last 100 years (approx. 1 degree of rise). The last 5 years is simply a pause like many other pauses over the last 100 years. The reverse during the 40’s was much larger, but it soon turned upwards again in the 50’s.
The graph is clear – we are going up (and accelerating) and we won’t be going down until we stop polluting our atmosphere. We are currently heading for 550 CO2e ppm and on towards 700 ppm by 2100. So we better get our act together!
Re: #198
> So what type of scenario would make climate science WRONG on the global temperature issue?
I think a negative trend in global temperature over a period of > 15 years would do it, assuming no major volcanic eruptions.
Not that I think that is the least bit likely, but if it did occur I would certainly wonder if something was being missed.
Just as an aside, it’s always interesting to look up the current year’s information when anyone mentions some old science as being bogus, just to see what’s new. As I mentioned in the recent thread on journalists, it really doesn’t take hardly any time at all to get a new clue when someone brings up an idea the journalist doesn’t know whether to rely on or not.
E.g.:
http://scholar.google.com/scholar?&q=nuclear+winter&as_ylo=2008&btnG=Search
http://www.pnas.org/cgi/content/abstract/105/14/5307
From the Cover: Massive global ozone loss predicted following regional nuclear conflict
MJ Mills, OB Toon, RP Turco, DE Kinnison, RR, 2008 – National Acad Sciences
… The ozone losses predicted here are significantly greater than previous “nuclear winter/UV spring” calculations, which did not adequately represent …
Old work, even when wrong, sometimes leads to interesting new work. Easy, now, to find.
The drop that would break the trend would have to be more than say 0.2 degrees over 10 years, or say 0.3 deg over 15 years, or say 0.5 deg over 25 years. the fact is that the trend reversal has to overcome the 100 year established trend we have already had. Given that the acceleration of emissions has been mostly in the last 30 years, we have a lot of momentum built up in the atmosphere and we havn’t yet seen the effect of it (do yo agree Gavin).
Gavin
is it true that recent work by James Hansens team looked at the drop in temperature from a known epoch of time and compared that to CO2 drops during this time. I have found an explanation for it here.
====================================================================
This is what James Hansen is talking about : the Carbon Dioxide levels in the atmosphere were very high before about 50 million years ago, and then they started to decrease, and the effect of decreasing Carbon Dioxide in the atmosphere was Global Cooling of such an intense nature that it kicked off glaciation. (formation of Antarctica I believe)
But it would not have ended there. The Global Cooling was an overshoot. If the CO2 levels had remained the same after their fast reduction to 450 (give or take) ppm, then after the necessary time lags, the Earth would have readjusted from that violent cooling swing to the relevant average heat for that CO2 level. And that would have been high. Higher than today.
James Hansen is saying that if you look at the change in the levels of CO2 roughly 50 million years ago, and looking at the temperature swing that the sharp dip in CO2 caused, then you can use that to work out the the temperature swing out for the sharp rise in CO2 we are now experiencing.
He says that this historical data can be used to calculate what happens at the end of the swing, as well.
Here’s what he says (with his colleagues) :-
“Equilibrium sensitivity, including slower […] feedbacks, is [of the order of] 6 degrees C for doubled CO2…”
Equilibrium, that point at which the time lags are over and the swing is finished and come back to a balanced point, appropriate to the level of CO2 in the sky.
Sensitivity, that total change of global temperature in response to the CO2 signal.
===============================================================
Or in other words we know climate sensitivity on the earth with some good accuracy (ok we have cooling agents to which we need to take into account and they are uncertainly known – hence the error bars) and hence it is scientifically sound to argue that raising atmospheric CO2 by any amount is unsafe but to 450 ppmv and above as we are currently looking to do will cause humanity a lot of issues as the temperature rise is relartive to where we live globally and what we do on this earth, ie grow crops and irrigate water.
I cannot see how Mr Monckton can fail to appreciate this and why he continues to write such seeming nonsense. surely he must be funded.
[Response: No – he’s a freelance purveyor of nonsense. – gavin]
The whole article can be found here:http://portal.campaigncc.org/node/2096
Once again the detractors to the science of climate change are just being obtuse and silly.
I even read recently an exchange between an UK climate scientist and Martin Durkin (TGGWS) who were having an exchange about the programs errors or inaccurate graphs etc and found papers written that tried to show that the MWP and LIA were global in origin and not solely European. They were localised phenomena weren’t they?
[Response: Our best understanding is that there was a global pattern of climate anomalies (i.e. that there was a global pattern of shifting atmospheric circulation, altered patterns of precipitation, drought, etc). This isn’t really a matter of dispute. However, in terms of surface temperature changes over the earth it was probably largely a zero-sum game. We now understand (see e.g. the latest IPCC report, chapters 6 and 9 here) that the modest changes in solar and volcanic radiative forcing which led to a very modest (0.1 to 0.2C at most) warming of the globe, also led to substantial shifts in the so-called “North Atlantic Oscillation” and El Nino/Southern Oscillation, phenomena. This lead to very large regional changes, including alternating patterns of substantial cooling (e.g. tropical Pacific) and warming (e.g. Europe), sitting on top of very modest anomalies in global mean temperature. All reconstructions shown in the IPCC report indicate peak medieval warmth that at hemispheric scales was significantly below the warm of the past one to two decades. -mike]
Heads Up! Monckton Strikes Back!
http://scienceandpublicpolicy.org/monckton/chuck_it_again_schmidt.html
Re #206, he is not striking back, he is being daft.
Viscount Monckton writes:
But not a significant one since the sample size is too small. Monckton probably inflates the number of points by using monthly data instead of annual (for a phenomenon where the characteristic time scale for statistical significance is 30 years). It’s kind of like me saying temperature rose sharply here between 6:15 AM and 9:15 AM, dividing that into 181 minutely temperature readings so that the regression tests as significant, and concluding that the oceans will boil in a few days.
Rod B., The good Viscount would have difficulty locating his posterior with both hands and a flashlight even if given a GPS programmed to their coordinates. WRT his assertions (and they are nothing but) on temperature, see:
http://tamino.wordpress.com/2007/08/31/garbage-is-forever/
Russell Seitz posts:
Except that it’s not a myth. The major study held to “refute” it, Schneider’s 1984 “nuclear autumn” paper, made a mistake in plume height simulation such that it was off by a factor of three. If your plume heights are too short, the soot doesn’t enter the stratosphere in sufficient amounts, and the cooling is temporary and mild. If your plume heights are correct, it does enter the stratosphere, and the cooling is for two or three years and severe — quite enough to destroy human agriculture and with it, human civilization. Much as right-wingers might be unhappy with it, nuclear war is still a bad idea.
Mr. Seitz appears to feel that radiative-convective models can’t tell us anything of interest, since they conflate night and day and have no surface relief. Do any climate scientists here agree?
Re Monckton strikes back, it’s a pretty glancing blow: “the FalseClimate propaganda blog…has launched a malevolent, scientifically-illiterate, and unscientifically-ad-hominem attack on a publication by me”?
Wow. He should guest on Colbert.
reCAPTCHA: Champlain Won
Rod B (196):
I may be misinterpreting your question regarding the factor of four in solar intensity (the “flat Earth”). If you already know this explanation then I apologize, but it may be useful for other readers. It doesn’t matter if you have an electric field, a magnetic field or an electromagnetic field (sunlight) hitting a curved surface, you have the same problem. To calculate the total flux, you need to perform an area integral of the dot product of the field vector and the normal vector for each surface area element. Since the Sun’s rays are parallel to each other, they will be directly perpendicular to the surface (or parallel to the normal vector) at the Equator (on the Equinox), and will hit at glancing angles (perpendicular to the normal vector) at the poles. This makes for a nasty integration, where it is easiest to convert to spherical coordinates, etc. Luckily, Gauss comes to the rescue. (That precocious little bugger!)
Gauss came up with the following thought experiment. Imagine a weird object with contorted surfaces. Suppose you have a field vector, e.g. sunlight, passing through this volume. Since no sunlight is created within the volume, the flux passing through one surface must be the same as the flux passing through the opposite side. The surface area can be HUGE on one side (imagine a steep-sided conical hat), but the flux must be the same. Now imagine if one side happens to have an easy integration . . .
When I explain this concept to my high school AP students, I bring in a colander, with one hemispherical surface and one circular surface. Since this is for an Electricity & Magnetism class, I use magnetic field as an example, but the same principle works for sunlight. Imagine that you turn the colander upside down an a flat surface. You then pass a magnetic field straight down through the curved surface. The magnetic field will then be parallel to the normal vector at the highest point on the colander, and will be perpendicular to the normal vector around the rim. The angle between the two vectors will vary continuously between these points. As for the bottom surface, the normal vector always points down (away from the surface). Remember that the flux through the hemispherical region always is the same as the flux through the circular region. While the curved surface has a nasty integration, the circular area has a simple one: the normal vector is always parallel with the field vector. That means that you can replace the dot product with a product, or simply multiply the solar intensity by the area of a circle. Note that the area of a circle is one-fourth the surface area of a sphere. That may be the origin of the “flat Earth” conundrum. Or maybe I have horribly misread things . . .
I do recall what Dr. S. is referring to above, I think. For a story on nuclear winter, an illustration of the globe was excessively darkened to near complete blackness and published in some magazine (Time?) to make the idea more scary. (Rather like a more recent cover where they did the same thing to a picture of wossname during his murder trial.) No cite, sorry.
The current nuclear winter idea is being belabored here with Dr. S. with appropriate illustrations. It’s a better place to engage in it.
http://www.defensetech.org/archives/003108.html
Barton Paul Levenson wrote: “Much as right-wingers might be unhappy with it, nuclear war is still a bad idea.”
During the cold war there were policy makers who advanced the notion that a global thermonuclear war with the USSR and China would be “winnable”. In the 1980s, one US government official stated that following a nuclear war, “if there are enough shovels to go around we’ll be OK.”
It appears that some in the current US government and corporate elites have a similarly cavalier attitude towards the consequences of global warming: it will be “winnable” — for a small number of extremely wealthy and powerful people who will be able to command the resources needed to survive it.
Re#, Re# 205, Thanks Mike for the response. So the global 0.8C we have experienced in the 20th Century and the 0.6C latent in the Oceans is going to be quite significant then as it will be truely global but also localised such as in the Arctic?
[Response: Yes–that’s fair to say. The thing that makes the late 20th century temperature increases unique is really the globally-synchronous nature of the warming, which contrasts with the typical pattern of natural variation. Relevant to this also is our previous post on the Osborn and Briffa (2006) Science article that addresses this issue by looking at how the homogeneity of trends has changed over the past 1000 years using various climate proxy records. -mike]
Monckton has no shame. He accuses the APS of “crumbling” and in effect lying to the effect that his paper wasn’t peer-reviewed. His evidence? Nothing. Why doesn’t he just publish the reviews? To save you reading the whole thing:
Chris, you’ve been debunked here. Why not be a decent chap and actually answer the criticisms at a site where people have the qualifications debate you, rather than indulge in an “ad-hominem approach” like “For the second time, the FalseClimate propaganda blog, founded by two co-authors of the now-discredited “hockey-stick” graph by which”…? Or is Gavin’s plough a tad sharp for you?
I’m sure Gavin will be kind enough to indulge a detailed debate.
One more thing: the scientific method is not an algorithm.
[Response: He did publish the ‘review’ (it’s included in his letter to the APS linked above). Read it and you will realise why the ‘no peer review’ case is unanswerable. Plus the author of that review, Saperstein, very clearly states on the New Scientist piece that it wasn’t a ‘peer review’ – just a review of a peer. :) – gavin]
Ray, et al, I see your and Tamino’s point (saw his post here after I posted mine). BPL seems to agree with me (my inference within my highly constrained question) and you and Tamino don’t seem to really answer that Monckton’s mathematical analysis is incorrect. It was a curiosity question, might not have any significant (or any…) relevance, and asked simply if his regression analysis from 2001 through 2008 was mathematically accurate. I understand that such an analysis likely has no relevance to any long-term temperature trend, or anything else, and might be entirely mathematically inappropriate — which isn’t the same as “mathematically inaccurate”. I probably should not have used “incorrect” — it could be interpreted as inappropriate, which is not what I meant.
Jeff (212), thanks. Your description is mathematically more complete and informative. I think it is also what I was simplifying: the total energy/power flux from the sun striking half of the earth as a hemisphere (area of 2(pi)r^2 using dot products, integration and all), turns out to be mathematically equal to the flux striking head on the equivalent cross-section circle of area (pi)r^2. This is also mathematically equal to flattening the sphere to a flat area of 4(pi)r^2 and dividing the actual flux by four. This is what I said, agreeing with Monckton, is like using a flat earth with no day-night distinction. Though Monckton seemed to be trying to confuse, mislead, and imply something beyond my very simple comparison.
Rod,
Tamino’s analysis is quite clear–there is no downward trend. Monckton is simply flat-assed wrong.
Re: #217 (Rod B)
Let’s make an analogy: suppose we want to monitor the height of men who walk into a coffee shop in order to determine whether there’s a trend over time. The first person through the door is Shaquille O’Neal, I’m the next person. You may already have guessed that I’m not as tall as Shaq.
Along comes Chris Monckton and says, “the height of men walking through that door shows a pronounced downtrend.” This conclusion is based on two people.
Is this mathematical analysis incorrect?
(Re #220) and of course the answer is “depends on what you mean by ‘correct'”.
:-)
Same with Monkton despite Roy’s attempts to narrow down the query to a state where no answer that can be given in less than dissertation length would be immune to him twisting to make him “right”.
thinking hats is the captcha. Looks like the Oracle of Captcha has scored another one!
PS we shouldn’t mouth the Oracle’s words too often, in case we expose a pattern. People with nefarious aims seldom care whether the effort is worth it…
Ray, O.K…., I think. But, Tamino, if you follow Shaquille O’Neal through the door, then saying the height of men walking through the door is in a downward trend is mathematically accurate. Maybe meaningless; maybe inappropriate; but accurate. Ray, Tamino am I correct (accurate) here?
1) Nothing about Viscount Monckton’s a behavior is a surprise. Of course, his characterization of “the usual suspects” is likely to be rather far off the mark as an accurate description of the APS President’s actions.
2) But still, I once again invite people to examine the articles listed in #68 by Dr Gerald Marsh, to which I add:
9. June 2005 “No consensus on prime cause of global warming”
http://www.ft.com/cms/s/0/10ea480e-dba7-11d9-913a-00000e2511c8.html
10. Dec 2004, “CO2 cannot be called a pollutant”, letter to Financial Times
http://www.ft.com/cms/s/0/72a811d4-593e-11d9-89a5-00000e2511c8.html?nclick_check=1
I think one can make the case that Monckton would never have gotten an invite without Marsh. It would be truly fascinating to know the whole list of five names.
Has Marsh published any peer-reviewed articles on climate change?
3) And again, although he appears not to have started this, Dr. Larry Gould certainly helped out later, and one might examine his home page.
4) I observe a pattern that has been seen before…
Needless to say, free speech is fine, but maybe colleagues might want to ask such people why they want to damage their reputations, by opining on topics outside their expertise, and via OpEd, letters to editors, whitepapers on thinktank websites, etc, etc … but not in peer-reviewed credible publications. The Web has a long memory….
No, Rod. Basic statistics 101 is where you learn how many data points, over how much time, you need to state with a given level of likelihood of being right that a trend can be inferred from the data.
You’re confusing bullshit with statistics. This isn’t your fault, but it is why taking Stat 101 changes people’s lives and the way they view the world.
Recommended.
Rod B. #222,
Yes, correct, meaningless and inappropriate.
Gavin responds under #216:
…and a review by a “peer”, i.e., someone just as, eh, competent on the subject matter :-)
Re: #222 (Rod B)
Rod, no you’re not correct. If you said the 1st person through the door was taller than the 2nd, then that’s correct. But to use the word “trend” without being mathematically mistaken, you have to test statistical significance. The 2-person “trend” fails.
So does the “trend” in global temperature for *every* data set mentioned by Monckton. In the context of mathematics, trend means more than just “today isn’t as warm as yesterday.”
Rod B #222: yes, I would agree that Monckton’s statement may be construed by a lawyer as not factually false (why am I thinking of Bill Clinton?) :-)
“Downtrend” true for a suitable definition of “trend” — not the one used by scientists though, who would insist that in order to exist a trend must be statistically significant.
“Pronounced”, matter of taste… british lords are known for their weird tastes :-)
Counterquestion: do you see intent to deceive? I know I do.
Re #206
Monckton must move in some pretty sheltered circles. It can be deduced from his SPPI document in response to this posting, that he thinks the following were Ad-Hominem attacks…
“He amusingly…”
”But back to his main error”
“So he makes another dodgy claim.”
”There are many more errors in his piece”
“He bizarrely…”
and my favorite!
“Umm…”
Blimey, no wonder Monckton is so peeved, with such cutting attacks!
Hank, Tamino, Ray, Martin, et al. I’ll have to agree that the two man example is bad and can’t indicate a trend. However, three maybe, theoretically, might if you are willing to accept a humongous error. Still,. mathematically, Monckton’s 2001-2008 regression ought to have sufficient points for a mathematically accurate trend. Though I recognize climate stuff requires many more points over time to get to a reasonable margin of error, compared to other things. You all keep replying that his analysis is inappropriate (meaning an unacceptable margin of error) or cherry-picked. I don’t disagree or question that. I’m just wondering how someone can make a numerical error in the calculation of a linear regression, or, e.g., calculating an average; the mathematical algorithm is not complicated, pretty straight forward, and requires little advanced math. You are saying he did; but I suspect (though it’s my question) you are saying it was inappropriate and insignificant. Regarding my question, this is not the same thing.
Yes, my impression is that he was trying to mislead. But just because he may be acting like a dork doesn’t mean he can’t accurately calculate the average of squares.
Rod:
http://atmoz.org/blog/2008/01/29/on-the-insignificance-of-a-5-year-temperature-trend/
Re #229
“Monckton must move in some pretty sheltered circles. It can be deduced from his SPPI document in response to this posting, that he thinks the following were Ad-Hominem attacks…
“He amusingly…”
”But back to his main error”
“So he makes another dodgy claim.”
”There are many more errors in his piece”
“He bizarrely…”
and my favorite!
“Umm…”
Blimey, no wonder Monckton is so peeved, with such cutting attacks!
I agree for a classicist to not understand what ‘ad hominem’ means is surprising!
However it get worse, he claims to take the ‘high ground’ when he declares: “I shall refrain from any ad-hominem remarks of my own,”, and then proceeds to pile ad hom on top of ad hom!
The last three pages are nothing but ad hom, I didn’t attend Harrow but at my school we were taught to play the ball, not the man, (a non-classicist’s definition of ad hominem). I do agree with Monckton in one respect though, Monckton’s liberal use of ad hominem remarks does serve to indicate that his remarks are politically and not scientifically motivated.
A rather poor translation of Occam’s razor too!
I read the ‘peer review’ of his paper and as I posted elsewhere I found it extremely superficial, a proof reading rather than a review which didn’t address any of the science.
Monckton’s pretentious use of foreign phrases is rather annoying, however it is amusing when he gets it wrong such as when he uses per impossibile
Rod B #230:
“Still,. mathematically, Monckton’s 2001-2008 regression ought to have sufficient points for a mathematically accurate trend.”
So show us. If it ought, and statistics isn’t rocket science ;-) , so show us the results.
Rod 230, Tamino’s post is also quite convincing.
Rod, In order to establish a trend, we must do a statistical analysis on some quantity. Since you cannot even really define a meaningful standard deviation on a sample size of 2, I think we can safely conclude that there is no trend.
Any fool can lie with statistics. Using them to bring out the truth–that takes skill.
# 222 Rod B Says:
“But, Tamino, if you follow Shaquille O’Neal through the door, then saying the height of men walking through the door is in a downward trend is mathematically accurate.”
No it is NOT mathematically accurate.
Statistical analysis of time series is all about estimating how likely it is that some pattern occurred by chance. If it is highly unlikely it occurred by chance, then we can say it’s a trend.
To do that, you need a big enough number of observations. In general, the more observations, the more certain you can be. Only when you have sufficient observations can you say there is a trend, and there are standard statistical tests for this. In the same way, a horse that has won 20 out of 20 races is a safer bet than a horse that’s won only one from one.
In your case, everyone coming through the door will be a different height than the previous person, even if there is no trend at all. So measuring only Shaq and Tamino tell us nothing whatsoever about the existence or otherwise of a trend.
You also need to specify your “model”. Your example assumes, implicitly, that people are coming through the door at random. Is there something else affecting your observations that might not be related to an underlying trend?
You might need, for example to allow for the fact that Shaq’s team predictably only comes to town once every few years or that a family of pygmies is passing through town on their annual vacation today, or that every Tuesday the coffee shop has a “shortass hour” between 10 and 11, free coffee for midgets.
The effects of these known events, which have occurred in the past, can be estimated.
In the same way, climate models make allowances for, say, el Nino and la Nina events and volcanic eruptions.
There may also be random unobserved events whose effects are unknown. For example, the Secret Tall People’s Coffee Drinking Team may have been kidnapped by aliens.
So your sample needs to cover a long enough time frame so such things will not affect your conclusions.
If you don’t take acocunt of these (and other) things, then the results of your trend analysis are likely to be misleading.
That’s why this talk of a downward trend since 1998 is misleading.
You could take a look at the wikipedia entry on “trend estimation” as a starting point, or get a book about introductory econometrics from your library.
The statistical methods used in econometrics are generally applicable to discussions like these and the texts are mostly accessable – they have to be, because we economists aren’t as smart as real scientists.
Well, we’re beating hell out of a near dead horse. I went back and checked. The “trend” from 2002 thru mid-2008 is down as shown in Moncton’s paper. However, eyeballing other graphs (with all apologies :-) ), had he started in 2001, not so much; 2000? not a chance. Monckton also talks of downward trend since 1998. That too is accurate. However starting in 1997 or 1996 it’s not, depending on how the linear regression would handle 2008. Starting any other year back to 1860 it is not. This is all that I was asking about/questioning. You guys keep answering, in essence, ‘..but he’s a dork’, or ‘it’s meaningless’, or ‘it’s statistically insignificant or misleading’. I knows dat; wasn’t what I was asking.
But, I know, I’ve taken this thing beyond any worth. So I won’t belabor it further.
Re # 197 Rod B:
Why do you (apparently) assume those scientists and mathematicians haven’t had input into global climate modelling from the very beginning, or that the climate scientists (and graduate students learning the ins and outs of climate modeling) don’t consulted with mathematicians and computer scientists and other modelling experts?
More importantly, I suspect the real limitation of global climate models comes not from deficiencies in an understanding of the requisite mathematics, statistics, writing of computer code, etc, but rather from gaps in “our” knowledge of the complex dynamics of atmospheric and oceanic physics that has to be incorporated into those models – that knowledge is likely to come from climatologists and oceanographers, not from outsiders.
> why do you (apparently) assume
Er, because we’re fun to watch? Boring.
Unfortunately, as long as you keep using the word “trend”, it IS what you are asking. And without the word “trend”, it is a meaningless question anyway.
So what’s your point? Are you hair-splitting over exactly *what* Monckton is lying about? He’s clearly lying, so I suppose classifying his lie might be an interesting exercise to some, but not to me.
Rod #237, point taken.
Note that the Viscount’s use of “trend”, as apparently borrowed by you, is not too different from your use of “temperature” for single molecules :-) Yes, we scientists may forget when folks are struggling for understanding rather than terminological precision — which is so central in science.
And he is a dork.
Rod B,
Please show us your raw data and your calculations.
Please also ensure you have included the noise level and significance calculations. We need to see your raw data and since this is only 5 years data, should be easy to produce.
Basically, I’m skeptical of your results.
Re #197, classic denialist rhetoric as per usual. Another flawed attempt to undermine GHG theory.
Rod B posts:
No, it is NOT accurate. You have a fundamental misunderstanding here. You can’t just calculate a linear regression to find a trend. A linear regression isn’t just a line, it’s the significance of the slope as well. A trend that isn’t significant is not a trend.
Gavin, under the heading “Schmidt’s errors”, Monckton accuses you of making I think 13 errors.
Could you please do all of us a service and rebut his accusations so that we can clearly see you are right and he is wrong?
[Response: I leave it as an exercise to the reader (or I would if I were writing a textbook). But it could be an interesting exercise in any case. Which of these claims seem credible to you and why? I might add an addendum at the weekend. – gavin]
Re: #237 (Rod B)
Rod, you’re the one who’s beating a dead horse because for some reason you refuse to admit that Monckton isn’t just being stupid and/or misleading, he’s actually wrong. The word “trend” has a meaning. It does not mean “the slope of a linear regression is non-zero.” That will always happen, even if you analyze a series of random numbers. If that slope is statistically indistinguishable from zero, then you have no evidence for a trend. But Monckton says “pronounced downtrend,” not only making him wrong, but a propagandist as well.
Nobody said he can’t add. But his statement is not mathematically correct.
RE: Rod @237
“The “trend” from 2002 thru mid-2008 is down as shown in Moncton’s paper.”
“You guys keep answering…‘it’s statistically insignificant or misleading’. I knows dat; wasn’t what I was asking.”
I think the point here is that if you use the term trend (without the scare quotes you used in the line I quoted) in a paper on science, directed at scientists, it should be safe to assume you intend a technical, scientific meaning of the term. In this usage, I believe that a pattern of observations is definitively NOT a trend if it does not reach statistical significance.
Let’s see if we can discern a “trend” from two data points:
1. As reported by Associated Press, yesterday “Exxon Mobil reported second-quarter earnings of $11.68 billion … the biggest quarterly profit ever by any U.S. corporation … Setting U.S. profit records has become commonplace for Irving-based Exxon Mobil. The $11.68 billion topped its own U.S. record of $11.66 billion, posted in the fourth quarter of last year. Right behind that was the $10.9 billion it reported to start 2008. Exxon Mobil owns the record for at least the top six most-profitable quarters for a U.S. company, as well as the largest annual profit.”
2. As reported by The Wilderness Society, on Tuesday of this week “allies of Big Oil in the Senate” blocked passage of legislation that would have renewed the investment and production tax credits for wind and solar energy and provided tax incentives for high-efficiency automobile technology.
The problem of anthropogenic global warming is real, and extremely serious — and Exxon-Mobil and other fossil fuel corporations fund a campaign of deceitful propaganda to prevent the public from realizing this.
The solutions — clean, renewable energy technologies that would enable a rapid phase-out of fossil fuels — are at hand, and Exxon-Mobil and other fossil fuel corporations bribe legislators to prevent even meager tax incentives to spur the development of these new energy industries.
Does anyone detect a “trend”?
Oh! Boy!
I meant that I was beating the horse; so you can get off yours, tamino.
My data is Monckton’s linked article and various graphs I have coming from GISS, HadCrut3, et al sources. They’re not secret or unknown or difficult to look at.
You guys will go to no end to avoid saying Monckton once in a while maybe by chance can add and subtract. His data from 2002 to 2008 is sufficient to establish a mathematical trend. The mathematical accuracy depends simply on the error and standard deviation. But I was (maybe wrongly) using the term “trend” loosely (which is why I put it in quotes, not to scare (???) people). You all keep saying that, numbers or not, a presumed trend is meaningless unless it logically fits the context, and a 5-6 year analysis is meaningless within the context of climate. I keep saying I know that and agree with it. But you all keep pounding away. So, I’ll ask, no more, no less, does the smoothed out global temperature measurements decrease between 2002 and 2008? (regardless of Monckton’s terminology, which I have admitted ad nauseam that I think is misleading.)
Chuck (238), so you claim the writers of , if not the most, one of the top half-dozen complex complicated mathematical models could whip it out like eating Cheerios in the morning, and could get absolutely no benefit what-so-ever from folks, who designed models for something other than climate, checking out a few instructions, algorithms, etc. from time to time. Boggles the mind.
Even more mind boggling and downright astonishing is how my thought here, as pete best says (243), meets the standard for, “classic denialist rhetoric as per usual. [and] Another flawed attempt to undermine GHG theory.” Wow! — suggesting that the climate model developer/architect might find some improvement by asking Jeanie down the hall in the astrophysics model shop????
[Response: I’ve never had much useful input from astrophysicist modellers, but I’m still young. But climate modelling is a very open field, and we certainly get input from mathematicians (I started out as one), oceanographers, meteorologists, dynamicists, sea ice specialists, biologists, geologists, atmospheric chemists, remote sensing experts etc. Some of them are in the same building, but mostly they are scattered across the world. The biggest issues in bringing so many people together, is that they often do not appreciate the constraints that GCMs impose on more detailed models – overall conservations, consistency and appropriate levels of approximation. – gavin]