Abrupt changes in GHCN station-level temperature records contradict the anthropogenic global warming (AGW) claims.

Guest post by Jens Raunsø Jensen

Preamble

Inspired by a statement by Dr. Kevin Trenberth in the e-mails referred to as Climategate 2.0 (#3946 discussed here), it is hoped that climate scientists will have “an open enough mind to even consider” that the global warming of the 20th century could have occurred mainly as abrupt changes in mean temperature linked with natural events. Observational data supports that claim, at variance with the AGW “consensus view”.

Summary

Abrupt or step changes in temperature regime has been the subject of many discussions on this and other blogs and in the peer reviewed literature. The issue is not only statistical. More importantly, any presence of major step changes in mean temperature regime may contradict the claims of the AGW theory and models, i.e. the claims of increasing and accelerating temperature and of human emissions of GHGs being the major cause for the relatively high temperatures in the second half of the 20th century.

In this post, 232 complete and unadjusted GHCN station records are analysed for step changes in the period 1960-2010, and it is argued that:

  • Abrupt changes in temperature linked with natural climate events may be widely responsible for the “global warming” during the second half of the 20th century.
  • 50% of sample stations have not experienced increased mean temperature (”warming”) for more than 18 years.
  • 70% of Europe stations have not experienced warming for more than 20 years.
  • The relative role of natural processes in global warming is very likely underestimated by IPCC.
  • The global average temperature curve is ”apples and oranges” and is widely misinterpreted using linear trend and smoothing techniques as indicating a pattern of widespread uniformly increasing temperature.

Objective and methodology.

The post is in continuation to my earlier post on the subject (http://wattsupwiththat.com/2011/08/11/global-warming-%e2%80%93-step-changes-driven-by-enso/ ), now including a near-global station level analysis. The post is based on a ppt presentation including additional details given at a researcher’s workshop at University of Copenhagen, 15th November 2011 (http://www.danishwaterforum.dk/activities/Researchers_Day_Climate_Change_Impact_2011.html ).

The objective with this analysis has been (i) to examine the land-based temperature records at station and higher levels for the presence of step changes during the period 1960-2010, and (ii) to assess the implications for our assessment of global warming during that period. Please note that the objective has not been to dismiss a (likely) presence of an anthropogenic warming signal, or to establish a climate model, or to make projections for the future. The issue is step changes in observational data during 1960-2010.

I have used the documented Regime Shift Detection tool of Rodionov (2004, 2006; www.beringclimate.noaa.gov/ ). The results are considered to be statistically robust (ref. the ppt presentation for details on parameter settings and a verification of the assumptions of constant variance and a likely negligible influence of autocorrelation).

The station level data is from GHCN (“after combine”, http://data.giss.nasa.gov/gistemp/station_data/ ) and include ALL stations with a complete record in the period 1960-2010 in broadly defined sampling regions (ref. Fig. 1).

A total of 232 stations were identified, with 54% located in Europe and Russia. The sampling criteria result in wide differences between the “regions” in terms of station number, density and distribution. Also, the “regions” are more or less homogeneous climatologically. However, this is not of material importance for the following discussion and conclusions.

Fig. 1. Distribution of sample stations according to sampling criteria.

Results

Significant step changes are widely found in the T-records and representative examples for 3 “regions” are shown in Fig. 2a-c. The temperature increase in the steps is typically of a size which is comparable to the often quoted global warming during the 20th century.

Fig. 2a. Alaska T-anomaly (n=9). Step, 1977; T-change = 1.5 oC; significance 0.000001

Fig. 2b. Fichtelberg, Europe. Step, 1988; T-change = 1.0 oC; significance 0.00009

Fig. 2c. Malacca, South-East Asia. Steps: 1978, 1990 and 1998; T-change = 0.4+0.3+0.4 = 1.1 oC; significance, 0.0004, 0.0007 and 0.003.

Warming during 1960-2010 was clearly a non-linear process at station level, with the step pattern differing among the “regions”. The global average T-anomaly curve, constructed by averaging across station-level T-anomaly curves, is therefore highly deceptive in propagating a message of near-linearly increasing temperatures, contrary to the actual processes at station level. Thus, the global T-anomaly curve is inherently “apples and oranges” and can not be used to identify a meaningful global AGW trend if the step changes are neglected. Then, the apparent AGW trend will in reality mainly capture the aggregated effect of the sudden step changes (as e.g. in Foster and Rahmstorf, 2011).

The steps are concentrated in few short periods. Disregarding 39 steps after 2005 (considered highly uncertain and “in progress”; 2/3 ups and 1/3 downs), it is found that:

  • The steps occur predominantly (58%) in three 3-year periods: 1977/79, 1987/89 and 1997/99 (Fig. 3).
  • 72% of all stations, and more than 50% of stations in each “region” (except Arctic), have one or more steps during these periods (e.g. 89%, 56% and 93% of Europe, Russia and South-East Asia stations, respectively; Fig. 4).
  • 78% of Europe stations have a step change in 1987/89, during which the major part of the entire warming of the 2nd half of the 20th century apparently took place.
  • 2 or 3 steps are common in South-East Asia (especially 1987/89 and 1997/99), but one step only is common in records from Alaska (1977/79), Europe (1987/89) and Russia (1987/89).

Fig. 3. Distribution of step changes by year of change.

Fig. 4. Percent of stations with one or more steps in indicated 3 periods.

Similar step changes are identified in national average records (ref. link to presentation above): US contiguous 48 states (GISS): 1986 and 1998; Australia (BOM): 1979 and 2002; and Denmark (DMI): 1988. The steps in the Global T-records are: Crutem3gl: 1977, 1987 and 1998; GISS L/O: 1977, 1987 and 1998; and Hadcrut3: 1977, 1990 and 1997.

The steps are statistically highly significant. But are they supported by a probable physical cause? The answer must be yes for the majority of steps. The steps occur in a temporal and spatial pattern coinciding with well-documented events and regime changes in the ocean-atmosphere system:

  • 1976/77: the great pacific shift from a “cold” to a “warm” mode (e.g. Trenberth, 1990; Hartmann and Wendler, 2005).
  • 1987/89 and 1997/99: the two clearly most intense El Niños of the period, 1986/88 and 1997/98, with the intensity here defined as event-accumulated nino3.4 anomalies (NOAA’s ONI index); there were two less intense events in 1982 and 1991, the impact of which was probably occluded by the major volcanoes El Chichon and Mt. Pinatubo.
  • A regime shift in NH SST in 1988/89 (Yasunaka and Hanawa, 2005).
  • A new regime of constant temperature after the 1997/98 El Niño, i.e. the now widely accepted “hiatus” in global warming.
  • Documented step changes and regime shifts in marine ecosystems, e.g. the late 1980s in Europe and in the Japan/East Sea.
  • The short-term regionally diverse global impact of ENSO events is generally well-known.

The empirical evidence, from this station level analysis and other sources, is unequivocal: the step changes in mean temperature are likely real and associated with natural events. The physical mechanisms remain to be understood, and this is certainly not to claim, that ENSO events are the only elements of the natural cause-effect chain.

It is therefore concluded, that the major part of the temperature change (global warming) in the 2nd half of the 20th century occurred as abrupt changes in mean temperature associated with natural events in the ocean-atmosphere system. Still, a warming/cooling trend – albeit relatively small compared with the step changes – could of course be hidden by the regime change model. But it seems inconceivable, that steadily increasing CO2 levels could be responsible for the major sudden changes observed as e.g. in Alaska in 1977, Europe in 1988 and South-East Asia in 1998. In principle, the natural events and step changes could have been amplified by human caused warming, but this is currently pure speculation.

Implications when accepting the presence of steps

“Increasing temperature and accelerated warming” : this study does not support general statements like that. The bulk of the “global warming” has likely taken place in abrupt steps, and 50% of the stations analysed has not experienced any significant warming for more than 18 years (Fig. 5). In Europe, 70% of the stations have not experienced significant change in mean temperature for more than 20 years.

In South-East Asia, the median value is 13 years as many stations here also experienced a step change in 1997/98 (Fig. 4).

Fig. 5. Years of constant T-mean prior to 2010. Box-Whisker plot, 1st and 3rd quartiles. (note: uncertain up and down step changes during 2006-2010 are disregarded).

Challenging the IPCC consensus view, i.e.: “Most of the observed increase in global average temperature since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse-gas concentrations”. However, the finding above, that abrupt changes linked with natural processes likely account for most of the increase in temperature during 1960-2010, contradicts the IPCC claim regarding the relative importance of natural and human causes. Thus, when IPCC (AR4) can only reproduce the T-curve by including GHG effects, then logically

  • either the IPCC GCM models do not adequately model the natural processes of high significance for the temperature variations (there is still low confidence in the projection of changes in the ENSO variability and frequency of El Niños, ref. the recent SREX-SPM IPCC report),
  • or/and the IPCC has overestimated the climate sensitivity to CO2 changes by eg. attributing natural temperature increases to CO2-induced feed-back processes.

    In either case, the relative importance of natural processes for the T-changes has likely been underestimated by IPCC.

Conclusion

This study has established that step changes in land-based temperature records during 1960-2010 are common and very likely real and linked with natural climate events. The step changes are statistically highly significant and with a systematic yet regionally diverse pattern of occurrence coinciding with major climate events and regime shifts. This finding has far reaching consequences for our analysis of climate records and for our assessment of global warming.

Thus, although many different statistical models can be applied to explore the pattern of T-change, the presence of step changes invalidates the widely used statistical techniques of linear trend and smoothing as means of identifying the pattern of temperature variation during 1960-2010.

Furthermore, the step changes account for the main part of the temperature changes during the 2nd half of the 20th century. The logical consequence is that natural processes have been the major cause for the temperature change during this period, leaving a secondary role to other causes such as the anthropogenic greenhouse effect.

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trbixler

Jens Raunsø Jensen
Great work and very interesting thinking on climate with respect to temperature. The obvious question is why. At least the question has now been postulated.

Rhys Jaggar

I trust that, should this research hold up, that a CONDITION of IPCC report 5 being ALLOWED TO BE WRITTEN will be a requirement to:
1. Acknowledge the implications of this research.
2. State that the IPCC has denigrated those who suggested such research for 20 years.
3. Ensure that there is a political price to pay for those who did that denigration.
4. That henceforth, the only criterion for research being included in IPCC reports will be its scientific validity.
Any chance of that do you think?

jimbojinx

Great report…and something I had not even thought of !

JT

“However, the finding above, that abrupt changes linked with natural processes likely account for most of the increase in temperature during 1960-2010, contradicts the IPCC claim regarding the relative importance of natural and human causes.”
Lets not forget that a complex, chaotic, non-linear system like the climate system might respond to a steady anthropogenic forcing with discrete (stepwise) state changes. Thus the contention that
“The logical consequence is that natural processes have been the major cause for the temperature change during this period, leaving a secondary role to other causes such as the anthropogenic greenhouse effect.”
is not necessarily correct as it could be that the observed “natural processes” are themselves the natural effects of the anthropogenic greenhouse cause.
However, I do agree that
“the presence of step changes invalidates the widely used statistical techniques of linear trend and smoothing as means of identifying the pattern of temperature variation during 1960-2010”
is quite likely to be correct.

Alan Statham

This is laughable. Your starting premise – “any presence of major step changes in mean temperature regime may contradict the claims of the AGW theory and models” – is wrong. You’ve used an arbitrary subset of the available data. Your methodology consists of drawing arbitrary lines on that data. Your conclusions, as a result, are wildly erroneous. Watts of course lacks the critical thinking skills necessary to discriminate between science and nonsense.

Gary

The regime change analyzer is a nice tool. Would you explain how it works in layman’s terms, how you applied it to these time series, and the reason it’s an appropriate statistical method? The PPT link is a little too brief to get a good understanding of it.

Pamela Gray

This study highlights why, from time to time, farmers lose their shirts. Only the well-seasoned shirt losers change to another crop fairly quickly. Currently I know of one or two who have planted the same field of spring wheat, year after year, only to have it frozen out by June. Back in the 70’s it was crop after crop of peas that wilted under a hot Sun and warm nights by June.

Jim murphy

what is the % of C02 in the atmosphere? .004%? What part of that is natural and what part is “anthropogenic”? Does anyone know? Even if we stipulate that there is some greenhouse effect caused by man how significant is it compared to natural green house effect? How significant are land based temp records when most of the planet is water or ice? I don’t think the science is settled.

Stephen Richards

This is something that Bob Tisdale has shown on numerous occasions and yes it appears to be real.

Urban Sandberg

Wow this is really interesting. Wonder if this will reach the public.

Stacey

Sorry if I am being stupid but I can’t see Trenberth’s comment in the link to email 3046?
Regards
S
REPLY: Yes, I don’t see it either, perhaps the number for the email he gave is a typo (I added the link) – So I’ve removed the reference to Dr. Trenberth for now until Jens can clear up the discrepancy – Anthony

Pamela Gray

Reasonable thoughts JT, except there are well documented natural mechanisms, with all the necessary energy and teleconnections, for such temperature shifts. There is no documented CO2 driven mechanism with enough energy to cause such things to occur in the oceanic-atmospheric regimes highlighted in the study. Until you can overrule a known cause, you cannot propose another driver unless you can clearly delineate a reasonable CO2 mechanism. In addition, recent studies of oceanic-atmospheric events (IE tornadoes, hurricanes, blocking highs, etc) show no correlation whatsoever with increasing CO2.

cui bono

This is brilliant work!
It seems similar to ‘punctuated equilibrium’ (popularly called ‘evolution by jerks’) which was vociferously denigrated when first proposed, but now seems generally accepted. Things change slowly for long periods, and then a specific environmental change triggers a sudden major revolution. Staircases, not gradual slopes.
Perhaps this is the start of bringing Climate Science up-to-date with other sciences?

Crispin in Waterloo

@JT
“Lets not forget that a complex, chaotic, non-linear system like the climate system might respond to a steady anthropogenic forcing with discrete (stepwise) state changes.”
+++++++++
I agree that the possibility should be considered. What is needed is for the IPCC, in its documents, not just by mouth, to entrench the idea that the steps are real, important, and traceable. The implications will follow. At the moment either due to ignorance or attitude, the IPCC does not consider that most temperature change is natural. There are a group of scientists, some of whom do very good work, supporting the view that CO2 from anthropogenic sources is not just a cause, but the major cause of temperature rises. I do not understand how Trenberth, for example, who is obviously brilliant and a dedicated researcher, can support so publicly the CAGW view when his own works are used by investigators to demonstrate the paucity of that same theory.
If the IPCC were to entrench in its works the view that the climate is indeed complex, chaotic, non-linear and poorly understood, keeping an open mind would be a pre-requisite for working on its reports. This has not been the case to date because, apparently, of the premature conclusions about human influence on the climate (which might be between almost none and approximately zero).
That the statistical techniques used to estimate the past and future climate are inadequate and hiding the meaning within the records does not surprise me at all. Re-smoothing smoothed data sets, including trends in data sets as independent variables (!) and misapplication of sophisticated statistical tools (hockey stick generators) seem to have blinded otherwise competent scientists to what is going on.
The fact that Enron (etc) worked out how to capitalise on the difference in CO2 emissions between oil, coal and natural gas is no surprise either. Big business with imaginative employees seeking private profit at public cost is hardly news, is it? The PR campaign to promote “Scary Movie 6, the Climate Catastrophe” is, like its prequels, a parody of the scientific method and academic discourse. The whole ‘green job’ thing is just another set of opportunists seeking private profit at public cost. The green politics movement is just another power grab rooted in selling guilt and accountability to a populace that is naturally considerate of others and respectful of their own acts and attitudes.
From http://en.wikipedia.org/wiki/Carpetbagger
“In the United Kingdom, the term was adopted to refer informally to those who join a mutual organization, such as a building society, in order to force it to demutualize, that is, to convert into a joint stock company, solely for personal financial gain.”
“…they are said to have politically manipulated and controlled former Confederate states for varying periods for their own financial and power gains…”
We are surrounded by climate carpetbaggers.

Pamela Gray

How is the selection of sites arbitrary Alan? Are you saying his selection criteria was bad and was purposely done to prove his bias? And are you saying that after discovering these step changes, he “eyeballed” the step change lines and free handed them in some sort of arbitrary way? What you are accusing this researcher of boarders on unethical research practices. Is that your accusation? If it is, please show your evidence of such biased unethical research practices.

R. de Haan

Jim murphy says:
January 5, 2012 at 6:36 am
“what is the % of C02 in the atmosphere? .004%? What part of that is natural and what part is “anthropogenic”? Does anyone know? Even if we stipulate that there is some greenhouse effect caused by man how significant is it compared to natural green house effect? How significant are land based temp records when most of the planet is water or ice? I don’t think the science is settled.”
According to Jan Veizer the anthropognic contribution to the annual CO2 budget is 5%.
SEE HIS CANADIAN TESTIMONY POSTED EARLIER AT THIS BLOG
He also said: “to claim that CO2 drives the climate is similar to claim that the Economy of Puerto Rico is driving the World Economy.
http://wattsupwiththat.com/2012/01/01/canadian-senate-testimony-skeptic-side-now-being-heard-in-canadian-politics/

R. de Haan

I think Joseph D’Aleo and or Joe Basrardi had a similar article about the step changes in the temperature record triggered by El Nino’s.

ferdberple

Crispin in Waterloo says:
January 5, 2012 at 6:51 am
The fact that Enron (etc) worked out how to capitalise on the difference in CO2 emissions between oil, coal and natural gas is no surprise either. .. We are surrounded by climate carpetbaggers.
climate carpetbagger: Noun – one who exploits or manipulates fears over climate change to gain financial or political advantage..

Shevva

@Alan Statham says:
January 5, 2012 at 6:17 am
Sorry my debating team gives you an F, just blowing hot air does not advance the discussion, it just shows your an angry little man.

J Solters

It should be relatively easy to show whether Mr. Jensen’s step-change temperature measurement numbers are correct or incorrect. If the measurements are reasonably accurate, IPCC warming theory clearly must be revised. A few more days of WUWT commentary should assist the review process.

slow to follow

It’d be nice to see how these results compare to 1900 to 1960.

Why are the “steps” always up?

Titan 28

Re Alan Statham:
Your aspersion regarding Anthony Watts tells us more about you than it does about him. Anyone who has read this blog, even those who now and then disagree with WUWT, realize Anthony Watts is a man of integrity and smarts. If you have an argument to make about this particular entry, then make it. Don’t just snidely squeak from your hole in the ground. Put another way, you think you’re so smart, how about showing us? Make the case.

Tom in indy
jens raunsø jensen

Stacey – and Anthony,
Sorry about the mistake, the email reference number to Trenberth’s statement should be 3946 (and not 3046), see eg.http://wattsupwiththat.com/2011/12/02/ncars-dr-kevin-treberths-ugly-intolerance-of-dissenting-views-from-other-scientists/
regards … jens

REPLY:
I’ve edited the post to reflect this clarification – Anthony

R. Gates

Of course the “natural” fluctuations would be seen as step-changes, as that is exactly what ocean (ENSO & AMO) and solar will look like when superimposed on top the anthropogenic signal. It is true that the anthropogenic signal is not accelerating, and is a nice slow but steady linear rise in temperatures, which is exactly what the Foster & Rahmstorf found when factoring out these “natural variability” factors:
http://iopscience.iop.org/1748-9326/6/4/044022
While skeptics are keen to criticize the Foster and Rahmstorf study, or at least significantly question certain areas of it, in fact, your analysis of the “step wise” increases only reinforces the validity of this study, and the ultimate finding that when factoring out the natural variability such as ocean, ENSO, and volcanic activity, a steady linear (i.e. non accelerating) rise in temperatures can be seen in the record. The “step wise” increases only occur when natural variations (i.e. ocean & solar & volcanic) line up with the underlying forcing coming from greenhouse gases. Thus, you’d expect a step-wise increase when and El Nino and warm PDO aligned, and even more so, when aligned with a solar maximum and minimal volcanic activity. Global temps will “step up” during these alignments of natural and anthropogenic forcings, and while they may fall back from the peaks of these “step up” periods, they never fall back to lower levels that break the underlying the long-term anthropogenic warming. This is exactly what Foster & Rahmstorf found and exactly what other “step wise” increase studies found– the steps are related to the alignment of all forcings during certain periods, but the underlying forcing from additional greenhouse gases can still be seen as a linear trend underneath all these “steps”.
If Foster & Rahmstorf are correct, (and related notion of “step wise” increases), then in the next few years we should get the opportunity to put these notions to a test, as it is very possible that we’ll get one of those alignment periods where the natural variations (i.e. solar & ocean) will once more align to the positive side with the underlying anthropogenic forcing. Such that for example, should we get an El Nino around the time of Solar Cycle 24 Max, we could see another step up in temperatures, with modern temperature records being set. These temps will of course subside once Solar Max has passed and the El Nino wanes, but the new underlying higher step will have been established. Time will tell…

Les Johnson

Alan Statham: your:
Your starting premise – “any presence of major step changes in mean temperature regime may contradict the claims of the AGW theory and models” – is wrong.
Nope. AGW theory rests on temperatures rising more or less in lockstep with CO2 levels. A step change would imply natural variation, or an unknown anthro component. NO AGW model shows step changes.
You’ve used an arbitrary subset of the available data.
Nope. As Jens states, he used ALL stations in the GHCN network, from the defined geographical areas, as long they have a continous record from 1960. The continuity is the only arbritary function. Granted, I would like to see North American data, too, south of 60.
Your methodology consists of drawing arbitrary lines on that data.
Nope. As Jens also explains in his Methodology, he uses a Regime Shift Detection Tool, and gives the reference and methods.
Your conclusions, as a result, are wildly erroneous.
Nope. You are shown to wildly erroneous, by not actually reading the posting by Jens.
Watts of course lacks the critical thinking skills necessary to discriminate between science and nonsense
Nope. That would be seem to you, actually, and your inability to read comprehensively.

Alan Statham said @ January 5, 2012 at 6:17 am
“This is laughable. Your starting premise – “any presence of major step changes in mean temperature regime may contradict the claims of the AGW theory and models” – is wrong. You’ve used an arbitrary subset of the available data. Your methodology consists of drawing arbitrary lines on that data. Your conclusions, as a result, are wildly erroneous. Watts of course lacks the critical thinking skills necessary to discriminate between science and nonsense.”
What an excellent example of warmist argument this is Alan. You offer no evidence for an assertion and make a personal attack on the publisher. And you are no doubt utterly bewildered when we do not immediately say to ourselves: “Gosh! Obviously I have been wrong all this time. Carbon pollution really does cause increased droughts, rainfall, sea level, acne, prostitution, obesity and everything.
What a dork!

Urederra

I recall reading one article written by Ross McKitrick where he shows a temperature graph with a big step just when the thermometers in the canadian surface stations were changed from mercury/alcohol to thermocouples. I may be recalling the whole thing wrong though.
If it is a question of equipment change, it would explain why in some countries there is just one step change and others have two or three. And it would be man-made, not natural. 😛
It would be nice if somebody could find the article I am talking about. 🙂 The only paper I can find is this one: http://www.uoguelph.ca/~rmckitri/research/nvst.html but here the plot is temperature vs. number of stations, and there is a big step right on the year 1990. I wonder if this graph is related in any way with the plots shown here. I cannot find any other article so maybe I am miss-remembering it.

EternalOptimist

It’s an interesting idea, and it sounds at least plausible, but it raises a whole lot of questions in a laymans mind.
Why did so many stations not register the step changes. Is it possible that we are seeing a churn of instruments or sites or recording methods. Do we see steps going in both directions

cui bono said @ January 5, 2012 at 6:42 am
“This is brilliant work!
It seems similar to ‘punctuated equilibrium’ (popularly called ‘evolution by jerks’) which was vociferously denigrated when first proposed, but now seems generally accepted. Things change slowly for long periods, and then a specific environmental change triggers a sudden major revolution. Staircases, not gradual slopes.
Perhaps this is the start of bringing Climate Science up-to-date with other sciences?”
Punk eek is still on the nose for many evolutionary biologists, especially I imagine for Dawkins. Despite the now overwhelming evidence for horizontal gene transfer (HGT), particularly among plants, most evolutionary biologists are sticking to the gradualist Darwinian meme. They believe that admitting that the gradualist meme was incorrect would reinforce the Creationists’ argument. Thus the biological community say certain things among themselves, but the message for the hoi poloi is entirely different. Good science is far less important than fighting the evil Creationists.
What we see in the climatological community is not much different to several other sciences. It just has more importance given the dire effects of crippling Western economies.

A physicist

Jens, the folks on SkepticalScience are questioning whether step-change models make any testable predictions. When we strip away the pointlessly tendentious SkepticalScience rhetoric (which I condemn!) we are left with reasonable questions like “If El Niños cause abrupt temperature step changes upward, why wouldn’t La Niñas cause equivalent abrupt temperature step changes downward?”
More broadly, step-change models have an unbounded number of independently adjustable steps. So why should we embrace arbitrarily-complicated step-change models, when non-step models like Foster & Rahmstorf (2011) — which are mathematically simpler and physically well-motivated — describe the overall climate-change data impressively well?
One key question is this: Do step-change models predict that simpler non-step models, like Foster & Rahmstorf (2011), will fit the climate-change data less well in coming decades?
Conversely, if step-change models cannot make even this one basic prediction, why should we embrace them at all?

kbray in california

Alan Statham says:
January 5, 2012 at 6:17 am
Alan Statham is a fictional character in the British sitcom Green Wing, played by Mark Heap.
http://en.wikipedia.org/wiki/Alan_Statham
Both Alan and his argument appear to be fictional.
REPLY: Yeah, he uses a Proxyserver also, appears to be one of our former friends (I won’t name him) who has been asked to leave for juvenile behavior but can’t stay away – Anthony

Most interesting approach. The regional look at things is one of the approaches advocated by Roger Pielke, Sr. It has much merit. It is unfortunate that so many got off on this AGW track. Had we spent half the wasted time and effort we would be much further along. It did and we can do little about it now but try and refocus on the real drivers. I have puzzled and will continue for some time I suspect to understand why we humans insist on reducing things, highly complex and poorly understood things, to a single value or catch phrase. That practice ultimately devalues and obfuscates.

Les Johnson

Leif: your
Why are the “steps” always up?
They aren’t. Fig 2a and 2b shows a negative step change.

Tom_R

A lot of the 1987-1989 step change may be attributed to the fall of the Soviet Union.

Steve Garcia

I will admit to a bias, but what I see in those three graphs (Figure 2a, 2b and 2c) is not what he sees. Yes, there are steps. The Alaska one I think is a real thing, because it is well documented that there was a step change in 1976-1977. I do have to ask what portion of Alaska he is including, though. The entire state? That is a real hodge-podge of regions. It seems like an odd amalgam to include. The other two I would consider to be artificial. The German one just happens to coincide with the onset of the IPCC, the great dying of the thermometers and the still unknown adjustments being made behind closed doors. The Malacca graph looks at first glance to also be an artifact of periodic adjustments which we have seen evidence of here at WUWT. That is, except for the 1976-1977 step, which, like Alaska’s same step, is supported by history and predates efforts to ‘prove’ global warming exists.
It would be instructive to see the raw data for all three. I don’t trust GHCN data; GHCN is too close to CRU and the IPCC.

P.F.

Urederra: Didn’t Anthony’s white wash/latex paint on the Stephenson screens show similar step changes — that local temperature records showed a step up when the screens were changed from white wash to latex paint?

Kelvin Vaughan

Alan Statham says:
January 5, 2012 at 6:17 am
This is laughable. Your starting premise – “any presence of major step changes in mean temperature regime may contradict the claims of the AGW theory and models” – is wrong. You’ve used an arbitrary subset of the available data. Your methodology consists of drawing arbitrary lines on that data. Your conclusions, as a result, are wildly erroneous. Watts of course lacks the critical thinking skills necessary to discriminate between science and nonsense.
No more stupid than saying that carbon dioxide back radiates when in practice if you look at the spectrum from the surface of the earth there is no back radiation to be seen!

Leif Svalgaard said @ January 5, 2012 at 7:33 am
“Why are the “steps” always up?”
Because temperature has been rising until recently? Presumably if the next 30 years is a cooling regime, the steps then will be down. Or is this too obvious?

Les Johnson

R. Gates: the Tamino/Rahmstorf paper mostly does not address the step changes in the years shown by Jens. If these were taken out, then the warming 1979-on would be even less than 1.4-1.75 deg/century, as proposed by FR2011.
Also, Jens makes this point in his post:
Then, the apparent AGW trend will in reality mainly capture the aggregated effect of the sudden step changes (as e.g. in Foster and Rahmstorf, 2011).

Rob Potter

I think Leif asks a good question:
“Leif Svalgaard says:
January 5, 2012 at 7:33 am
Why are the “steps” always up?”
I would like to know if there are similar station records from the cooling period from 1940-1975 (or whenever it was) that show similar down steps.
I think this is a good example of the “devil is in the detail” concept – by only looking at averages we are losing the real information in the data. I have a bone to pick with arithmetic means being used in weather predictions in a more general sense, but averaging across very large geographic regions (and using such averages to fill in places where the data is not available) really is losing most of the information.

Frank K.

Leif Svalgaard said @ January 5, 2012 at 7:33 am
“Why are the steps always up?”
This is a good question. What I’d also like to know is if these “steps” are seen in the numerical climate model predictions, and, if not, why not?

Stephen Wilde

Leif Svalgaard says:
January 5, 2012 at 7:33 am
Why are the “steps” always up?
What makes you think they were ‘up’ between MWP and LIA ?
The period 1940 to 1975 or so was only a very slight cooling so there might be no clear downward steps.

Kelvin Vaughan

Tom_R says:
January 5, 2012 at 8:23 am
A lot of the 1987-1989 step change may be attributed to the fall of the Soviet Union.
Is that the Russian Steppes?

Latitude

Leif Svalgaard says:
January 5, 2012 at 7:33 am
Why are the “steps” always up?
=======================================
Because we’re at the bottom……
….when you’re at the bottom, you can only go up
http://www.americanthinker.com/%231%20CO2EarthHistory.gif
If we went down from here, that would truly be unprecedented ……….

PRD

I’m sick and tired of being sick and tired.
I saw this http://forecast.weather.gov/product.php?site=SHV&product=PNS&issuedby=SHV coming out my local NWS office and couldn’t help myself after being inspired by two articles, one above, the other was “The ‘great dying of thermometers’ – helping GISS find the undead thermometers… and a response by Max Hugoson, June 7, 2010 at 9:49 am discussing the BTU content of air at various temp and humidity.
Below is my response. Edited for privacy.
Webmaster, please forward to the appropriate meteorologist.
Comments on: http://forecast.weather.gov/product.php?site=SHV&product=PNS&issuedby=SHV
Does the NOAA/NWS have any plans to calculate or report the actual stored energy in the atmosphere when making high temperature measurements? When making a claim such as the year 2011 was one of the hottest years ever the thought that degreed and accredited meteorologists seemingly ignore the fact that “cooler” air with substantially greater humidity contain a significantly greater quantity of heat energy makes the claims ring false.
You also appear to ignore, or simply not report the fact that the same energy delivered to the earths surface (soil) will heat the soil to a higher temperature when the proportion of water in the soil is at a theoretical minimum as we had through the 2011 summer. Owing to the heat storage capacity of the water molecule vs. the negligible heat storage capacity of air, and the re-radiation of the heat energy from the soil back to the atmosphere, it’s no wonder that 2011 easily ranks as one of the “hottest” years ever. Had we been receiving any significant amount of rainfall and had the same temperatures along with normal humidities then we would have something newsworthy.
Examples: 105 F and 15% R.H. = 33 BTU/cu.ft. of air vs. 85 F and 70% R.H. = 38 BTU/cu.ft. of air
As it is, the actual heat energy contained in the atmosphere was not significantly different compared to the normal values of the region surrounding Shreveport. Please make those clarifications in the record report contained on the home page of station shv.
I send this email from my company email address, but the opinion expressed is my own and does not necessarily reflect that of XXXXXXXXXXX.
Thank you, and I await a reasoned response disputing my arguments or a clarification of the record report on your webpage.
Phillip XXXXXXXXXX.
Senior Plant Chemist
XXXXXXXXXXXXXXX
O: XXX.XXX.XXXX
BB: XXX.XXX.XXXX

Spen

@JT
“Lets not forget that a complex, chaotic, non-linear system like the climate system might respond to a steady anthropogenic forcing with discrete (stepwise) state changes.”
I’m beginning to doubt whether the earth’s climate can be described as a chaotic system. Looking at the records the earth seems to have a remarkable temperature regulation system. There have not been wild excursions which you would expect from a chaotic, non-linear system. There have been changes over geological time but were these chaotic?.. The temperature over the last 1000 years appears to have been remarkably steady within a relatively narrow band. Just because we don’t understand the mechanisms doest make them chaotic.

Rob Potter says: “averaging across very large geographic regions (and using such averages to fill in places where the data is not available) really is losing most of the information.”
That is the problem with statistics. Picking start/stop over such a large time period one can demonstrate a reasonable clam. Jens is using raw data rather than the often used adjusted data that is then messaged further. It is an interesting look at temperature change in certain climate areas. Climate to my understanding is wet, dry, continental, tropical, marine, etc. Those are what they are because of continents and oceans local influence. If those climates warm or cool, it does not change the climate. But my profession is not climatology, just a curious George.

steveta_uk

I’m not clear on what the black lines in figures 2(x) represent.
It would appear to show a level period of some variable number of years with a step up (or down) at irregular intervals.
Is the “flat” region intended to convey that there is no trend in this period? e.g. 1976 – 2005 in figure 2a.
I think this is very important, because if there truly is NO trend during this interval, this implies that the natural decay after the step precisely matches the AGW signal as proposed by R Gates above – a precise match that is so unlikely that is can be discounted.
However if the flat line is just there to connect the steps, then the possibility of a saw-tooth that would naturally returns to zero except for AGW remains. Which is it?