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.
Anthony said:
“@ur momisugly Andy and Utahn – ‘Tamino’ has an agenda – he’d try to ‘debunk’ a straight line made of two points if it was posted here. Heh. Let’s see what Jens has to say.”
Is Jens still reading comments? I hope so and I will await an update/rebuttal of Tamino’s analysis, which looks pretty hard to rebut.
As far as agenda’s go, does that invalidate an argument? In addition, looking at the last 100 posts or so on this site it looks like there is a pretty clear agenda, since just about every post appears to either : implicate something besides C02 as a cause of warming; minimize or trivialize the impact of global warming, whatever the source; or show some flaw or uncertainty in the scientific literature or scientists studying AGW. Not even 1 post out of 100 that argues could have a problem from AGW?
Well said, Utahn. I don´t care about either Jens Raunsø Jensen´s, Watts´ or Tamino´s respective agendas – whatever Grant Foster (Tamino) may have said or done in the past hardly takes anything from the fact that he offers some pretty hardheaded statistical objections that torpedo every single one of Jens Raunsø Jensen´s core claims here. Surely, for this analysis to stand, Jens will need to show both that a) his regime shift model is superiour to others (providing some AIC support), and if so, b) what kind of underlying forcing that could have caused a net change over the timeframe 1960-2010.
He´ll need to find something presently unknown or undescribed: Given the undisputed fact that there is no net change in the ENSO contribution over the years 1960-2010, I think everybody can readily agree that ENSO could not possibly be responsible for any of the observed warming in this period, and the authors having published on regime shifts in the peer reviewed literature Jens claims to have read/be relying upon explicitly denounce “analyses” like this as common misunderstandings, so it is indeed quite a task Jens has assigned to himself.
Andy and Utahn, and Anthony Jan10 6:04am:
You are referring to a post entitled Steps at Open Mind by Tamino.
First, having tried recently to comment on that site only to be censored out, I do not feel inclined to respond to posts at that site which seems to be driven by a political agenda rather than by a wish to explore the science with an open mind.
Paraphrasing Willis, quote me correctly and I shall respond. Tamino misrepresents my post in his opening statement. My post does not “contradict man-made global warming” but contradict, as explicitly stated, some of the main specific claims of the AGW hypothesis. I clearly state that in my view an AGW signal – albeit relatively small – is likely to be present and could be hidden by the step analysis. I argue, that unless there is evidence (and not only speculations) that man-made warming is the main cause for the sudden steps, then IPCC has likely got the balance between natural and anthropogenic forcings wrong. It is the balance I am concerned with. A simple analysis of the primary temperature data along with other empirical observations on the physical and biological systems supports my argument, and as far as I know there is no supporting evidence for man-made warming to be the cause of the abrupt changes.
Tamino claims that my post does not even establish the central claim that station level records goes through step changes rather than linear changes (I assume that Tamino means linearly increasing when he talks about linear changes). The central claim is that abrupt changes are present. How much does it take for Tamino to accept a likely presence of abrupt changes in the T-records? I have demonstrated, not for one station but for the 232 stations with complete records in the broad regions analysed, that station level records widely display very significant abrupt changes in a systematic pattern somehow linked with documented natural extreme climate events in the period considered. Consequently, the observational data and supporting evidence questions the validity of assuming that the T-records are uniformly and linearly increasing during the period of global warming (as eg. assumed in Foster/Tamino and Rahmstorf). At least, Tamino and others now need to consider that possibility, rather than just dismissing the evidence as “silly”.
Tamino goes on with examples to demonstrate that basically any curve with a true trend may/will be interpreted by the step model as consisting of steps. Of course, this is trivial, and I already in my earlier post on the step changes made that caution. But the fact that such examples can be constructed does not disprove the real presence of many of the step changes. And why does Tamino cherry-pick the Malacca case with the many steps for his criticism? I would recommend Tamino and like-minded to analyse eg. the many European and Russian stations with only one step change occurring around 1988 and compare the performance of the step model with a linear regression model for the period 1960-2010. I have no doubt that in most cases the step change model will prove to be superior from a statistical point of view (also using Akaike’s information criterion, as I have tried early on in a few cases). However, comparing different models statistically is complex and likely to produce ambiguous results. The issue of physical support for the models is more important.
The crucial point which Tamino conveniently neglects is that there are independent observational and published evidence for the regime changes identified in my analysis. I suggest that Tamino and like-minded start with reading eg. Trenberth (1990) and ask yourself, if the step change in 1976/77 was real or not, and whether there is any evidence or high probability that this step is caused by man-made warming. The zero-hypothesis is a natural cause. Looking forward to see your assessment.
Regards … jens
@HenryP
The graph I cited is from Vose in GRL (2005). Here is a simplified draft version of this with open access:
ftp://ftp.ncdc.noaa.gov/pub/data/papers/200686amsp4.1rvfree.pdf
The datasets used cover the entire globe, using GHCN as the primary source:
Data for this study were compiled from 20 source datasets. The primary sources were the Global
Historical Climatology Network (Peterson and Vose, 1997) monthly and daily databases (which contain most of the data used in Easterling et al.), and two editions of World Weather Records (1981-1990 and 1991-2000). These global datasets were supplemented with acquisitions from Argentina, Australia, Brazil, Chile, Cuba, Greece, Iran, New Zealand, and South Africa. CLIMAT reports were used to update about 20% of thestations after 1994. In addition, high-quality synoptic
reports were included to fill recent gaps in about 10% of the stations (provided digital and manual checks indicated that the synoptic data closely matched historical monthly time series during periods of overlaps).
From the conclusion:
This appears pretty solid to me. At the very least, you´ll certainly need to present some very convincing arguments and thorough analyses showing why your selected 20 stations should perform better than a global assessment like this.
@HenryP
The graph I cited is from Vose in GRL (2005). Here is a simplified draft version of this with open access:
ftp://ftp.ncdc.noaa.gov/pub/data/papers/200686amsp4.1rvfree.pdf
The datasets used cover the entire globe, using GHCN as the primary source:
From the conclusion:
This appears pretty solid to me. At the very least, you´ll certainly need to present some very convincing arguments and thorough analyses showing why your selected 20 stations should perform better than a global assessment like this.
Dear Christopher
To quote from the first sentence of the report that you quoted:
Minimum temperature increased about twice as fast
as maximum temperature over global land areas since
1950,
I am sorry to say that this not corroborate my own findings at all,
in fact, as an example, look at what I got here:
http://www.letterdash.com/HenryP/de-forestation-causes-cooling
How would you explain the results I am getting there?
(I can prove that I am not ” making anything up”)
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
Try also following the discussion on this
http://wattsupwiththat.com/2012/01/08/the-moon-is-a-cold-mistress/#comment-860663
But dearest Jens,
you apparently still fail to understand that the empirical observations on the physical systems you are talking about do not support your argument at all – on the contrary, they explicitly contradict it. The net contribution of ENSO over 1960-2010 to the climate system of Earth is zero – once again, this is very well documented from the literature you claim to be familiar with. Do you seriously dispute this, if you take another look at ENSO over time?
http://cses.washington.edu/cig/pnwc/aboutenso.shtml
Over shorter timescales of, say, 5 years, ENSO is certainly able to cause abrupt changes in warming, and indeed, I think everybody will agree that the abrupt rises are likely heavily influenced by El Niño – but these will be followed by an equally sized and abrupt cooling influence over a timeframe of 50 years. Thus it is just not physically possible for ENSO to have caused these stepwise changes resulting in a net temperature increase over a timeframe of 50 years – unless it has been superimposed on a steadily increasing positive external forcing like e.g. GHGs or solar irradiance. Your conclusion about balance does not follow from your arguments: The overall net contribution from ENSO 1960-2010 is zero, while in the same time, the CO2 forcing increased by about +1,5 W/m2. The isolated radiative effect because of CO2 is simple radiative physics calculations using Arrhenius´ law, which is acknowledged by even most sceptics – I hope we can agree on that?
Why, then, is it that you appear to think that this suggests that IPCC (or anyone else, for that matter) has got the balance between natural (here ENSO) and anthropogenic forcing wrong? Considering only CO2 and ENSO, it is obvious that ENSO does have an important role in many or all your “shifts”, where it overwhelms the yearly CO2 signal by an order of magnitude for a short while. However, the balance of their respective contribution to the warming 1960-2010 is a 100% for CO2 and 0% for ENSO. There is no contradiction at all in this, as you appear to think.
I would very much appreciate if you would at least try to respond to this central point. It really is easy to see for any open mind.
P.S. You also appear to have misunderstood a couple of other things:
It is perfectly fine to look at natural climate drivers, but one cannot just throw out “natural variability” without a physical mechanism as an explanation – that is not a scientific hypothesis, but mere handwaving. It is well known and undisputed that CO2 has contributed about the aforementioned 1,5 W/m2 over the last 50-60 years. If you think that other sources have contributed more to the the warming in the same period, then you need to suggest a specific natural cause (or several ones) which could have contributed with a forcing larger than this.
I think you have misunderstood F & R quite spectacularly, if it is their ERL 2011 paper you are referring to. They don´t “assume” T-records to be linear (in fact, if you read Foster´s post, he even explicitly states that T-records need not be linear under the AGW hypothesis), and they actually don´t assume anything really – they remove the variation due to ENSO (and solar cycles + volcanic aerosols) – and then they get a linear trend.
For your hypothesis about ENSO causing shifts leading to an overall 1960-2010 warming stronger than CO2 to be true, the remaining warming trend/signal after this removal should be significantly weakened compared to the “raw” warming in this period. And it is not.
@ur momisugly Christoffer Bugge Harder
“Over shorter timescales of, say, 5 years, ENSO is certainly able to cause abrupt changes in warming, and indeed, I think everybody will agree that the abrupt rises are likely heavily influenced by El Niño – but these will be followed by an equally sized and abrupt cooling influence over a timeframe of 50 years.”
Can this just be assumed ? It seems to me as Jens hints that the idea that there must be a natural zero balance is still rather speculative. The wikipedia article on the ENSO phenomenon does not give the impression that it is as well understood as you claim.
An example:
“A joint study by the National Aeronautics and Space Administration and the National Oceanic and Atmospheric Administration concluded that climate change may contribute to stronger El Niños.”
Note the wording “may”. To a skeptical layman like myself this indeed does sound like much more study is required of the underlying mechanisms of these phenomena to make the kind of certain statements that you do in this area.
@Cubie
I work on microbiology and DNA sequencing, so in climate science, I´m also nothing but a sceptical layman. But to my mind, scepticism is a two-way thing: Sure, one should demand evidence instead of simply believing, but then one should also accept a claim when supported by overwhelming evidence – and one should not suggest hypotheses that are are odds with basic facts, or which make things more complicated without explaining more observations.
First of all, I certainly don´t say that there is a “natural zero balance” on all possible climate factors – I simply focus on ENSO because that is what Jens´ post here (and the previous one) hints at as a possible explanation. It is indeed very well documented that oceans do not generate new heat, they only redistribute existing heat back and forth – and to be able to induce a net heating of 0,7C to our climate system, basic physics obviously requires some kind of external heat source, i.e. external climate forcing. (This could, of course, theoretically still be a natural one (e.g. solar irradiance), but this is something that would need to be documented separately.)
That ENSO has, over time, a net forcing of zero, is not, as you appear to think, an “assumption”, but something that has been measured and well documented for many years. I really recommend this page again:
http://cses.washington.edu/cig/pnwc/aboutenso.shtml
I can point you to many other similar research pages like that if you are interested.
Since ENSO cycles only last for a few years at most, we have had numerous ups and downs in the timeframe since 1950 where we have good documentation, so there is not a shortage of data to evaluate this effect.
You agree that in the years 1960-2010, the ENSO curves show many equally significant cold shifts, too, right? Why, then, are only warm cycles apparently able to influence the climate system, following Jens´ argumentation? Clearly, every honest person with an intact common sense can readily see that this is absurd on its face. The likely answer is, of course, that ENSO is just short-term noise upon an underlying positive forcing, which enhances it in El Niño years and suppresses it in La Niña years but makes no net contribution to the balance at all over a timeframe of 50 years. Jens simply appears to ignore La Niña.
I have yet to see anybody, even arch-scepticists, even try to make a physically supported case for ENSO having any kind of trend over 20 years or more, and whatever one thinks of Jens Raunsø Jensen´s analysis here, then he obviously has not tried that either. And to do that would require quite an effort, which would possibly involve rewriting even the basic laws of thermodynamics. At the very least, he would have to provide some very good arguments as to why all measurements of ENSO hitherto have been wrong. And so far, he does not even appear to realise this gaping hole in his argument.
Let me emphasise that I don´t think he has written this out of dishonesty or stupidity, but I do find it puzzling that he is able to miss something so bleedingly obvious. Ferrgodnesssake, the software Jens is using is developed by people from NOAA where lots of professional researchers have analysed things like ENSO and its climatic importance for decades. Apparently, Jens must have thought that none of these had ever considered looking at their own data. I do know that every now and then, amateurs suddenly find new way none of the professionals had ever thought of, but it is much much more common for amateurs to just having misunderstood or overlooked some basics. If one amateur thinks that he has made a scientific breakthrough in his cellar, then to my mind, healthy scepticism should warn him to make damn sure by independent confirmation that there is not basic mistakes in his analyses or experimental design before making bold public proclamations about having invented a perpetuum mobile, a cure against AIDS or discovered cold fusion.
To me, this post is just another display of the profound lack of scepticism and Dunning-Krügerish disregard for facts all too often seen by other overconfident amateurs in many fields.
Just to clarify: I certainly don´t mean to say that CO2 alone has caused a 100% of the climate changes since 1960 – only that if you in an isolated CO2 vs. ENSO comparison sum the combined net forcings of just ENSO and CO2 in the last 50 years, then this amount to a total of about 1,5 W/m2 – and of this, CO2 has contributed 100% and ENSO 0%.
@HenryP
thank you for the answer. I appreciate your politeness despite my somewhat sarcastic response.
However, the only obvious responses I can think of why the global assessment of Vose does not corroborate your findings of minimum temperatures from 20 random stations is that your sample is likely to be either too small or not representative. One needs to be sceptical towards ones own findings, too, and certainly, Vose´s study is by far the more thorough one, right? 😉
Furthermore, I have had a look at your link here:
http://www.letterdash.com/HenryP/de-forestation-causes-cooling
and I must say that I don´t understand your reasoning about deforestation causing cooling. Leaving aside the fact that you don´t provide any documentation for the correlation with deforestation in Argentina, then exposing soil by cutting down trees might as well decrease the albedo unless trees are replaced with some new vegetation? And if trees are burnt, they produce CO2, too .- actually, tropical deforestation contributed about 20% to the yearly human CO2 output of about 29 metric gt…………..?
Jensen, you say: “Tamino goes on with examples to demonstrate that basically any curve with a true trend may/will be interpreted by the step model as consisting of steps. Of course, this is trivial, and I already in my earlier post on the step changes made that caution.”
But your conclusion in the post says:
“…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.”
So you admit that statistically significant step changes are commonly seen in known linear trends with noise, yet still believe that finding them invalidates those known linear trends?
And those noise-related artificial “step changes” explain the known linear trend, rather than the known linear trend itself??
Sorry Jens, autocorrect autoscrewedup your name!
CBH says:
http://wattsupwiththat.com/2012/01/05/abrupt-changes-in-station-level-temperature-records-contradict-the-anthropogenic-global-warming-agw-claims/#comment-861557
I quote again since it seems you did not get that, it says
“over global land areas”
So what happens over the oceans (71%) is not important?
I am saying the opposite as what you are saying, namely, I think my sample is more representative:
I have balanced my tables NH and SH latitude and & 70/30 sea -land as far as possible.
the reason why you can trust my results is because everyone (BEST, Spencer, etc) gets about the same for the means for past 3-4 decades: i.e. +0.14 degree C/decade warming.
I did provide a link showing a possible relationship between de-forestation/ greening and cooling/warming, in my blog here,
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
namely,
http://wattsupwiththat.com/2011/03/24/the-earths-biosphere-is-booming-data-suggests-that-co2-is-the-cause-part-2/
admittedly I still have to work on finding the correlation coefficient for which I need to find the actual data of the Leaf Area Index
I am hoping to get hold of the 3x Liu’s one day…
@ur momisugly Christoffer Bugge Harder
Thanks for your interesting reply.
“That ENSO has, over time, a net forcing of zero, is not, as you appear to think, an “assumption”, but something that has been measured and well documented for many years. I really recommend this page again:
http://cses.washington.edu/cig/pnwc/aboutenso.shtml ”
I honestly cannot see anything in that link that supports a net forcing of zero from the availible evidence. It is certainly true that Multivariate ENSO index shows plenty of La Niña events, however from around 1970 it seems that the recorded El Niño events become much more powerfull than La Niña. Would you agree to that interpretation?
“You agree that in the years 1960-2010, the ENSO curves show many equally significant cold shifts, too, right? ”
Same as above. From about 1970 El Niño appear to become much more intensive than La Niña. I am not aware if anyone has given any theoretical explanation of why this is so. The orthodox answer seems to be AWG influence. Which could be true but since the causes of ENSO are not fully understood this could be a premature conclusion.
Dear Cubie,
I have done a series of simple excel plots/correlation of the values of the yearly MEI (Multivariate Enso Index) with GISS Land-ocean temps over the years 1950-2011:
Data from these sources:
MEI:http://www.esrl.noaa.gov/psd/enso/mei/table.html
GISTEMP:http://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts+dSST.txt
CO2: ftp://ftp.cmdl.noaa.gov/ccg/co2/trends/co2_mm_mlo.txt
Forcing calculation formulas: http://www.esrl.noaa.gov/gmd/aggi/
Depending (very much!) on the beginning and start years, one cand get weak positive or negative trends for ENSO over timeframes of about 40 years, as you appear to suggest. E.g, the 40-year trend from 1972-2011 is negative, while the 1971-2010 is positive. However, none of this is remotely as strongly correlated with temps as CO2 forcing, neither the 1960-2010 record – which, needless to say, would be the very minimal requirement for Jens´ hypothesis to hold true – leaving out the physical fundamental problems………
…….because these are all much more important, as far as I see it: Whatever the sign of ENSO, even if it were strongly positive over some period (and it is not), this still wouldn´t change anything for the basic physical problem: The oceans by themselves still do not generate any extra heat to the system, which is necessary for the system´s net temperature to increase. You would still need to point to an external heat source to explain a net warming. I have nothing qualified to say about whether AGW has or will enhance the El Niño effects in the future (and in this case, I guess you would be likely to see an upward trend over the years), but this clearly still would not mean that ENSO by itself would be causing this net temperature increase, only that the yearly noise from the redistribution of heat would be more extreme.
Furthermore, if you check out Lyman et al. on the total upper oceanic heat content (OHC) 1993-2008 (not just the surface or the land temperatures):
http://www.nature.com/nature/journal/v465/n7296/pdf/nature09043.pdf
then the ups and downs of ENSO are barely visible on the OHC. This, to my mind, is just another clear illustration that Jens´ hypothesis of abrupt ENSO-driven persistent effect on the climate is nonsense.
And once again, if you check out this illustrative WMO graph of La Niña years:
http://www.wmo.int/pages/mediacentre/press_releases/images/gcs_fig_1_big.jpg
then once again, the overall trend even singling out the La Niña years goes in one direction. Even though 2011 was a La Niña year, it still ranks as one of the tenth warmest ever measured. This is, once again-again, just another big red flag that oceans are not driving any global warming.
Just to finish off, I´m no climate scientist, so some of the above might be a bit incomplete or overly simplified. There are lots of blogs by professionals out there doing a much better informed and more thorough job in explaining this stuff than I could possibly do, but I guess that unfortunately, most sceptics would tend to just dismiss many of them right away, so I have simply tried to present the best science-educated-climate-layman job I could muster here. And I certainly agree that there is a lot to be discovered out there and lots of AGW-related hypotheses we cannot show to be true with any reasonable certainity.
But on the other hand, there are also quite lots of hypotheses that, just based on the facts we already have, can indeed be clearly shown to be wrong, poorly thought through, incoherent, internally contradictory and rooted in misunderstandings, and Jens´ post here pretty much meet all these criteria. 🙂
Looks like discussion has waned. Oh well, on to the next “Anything But Carbon” explanation, I guess…
Utahn says:
Looks like discussion has waned. Oh well, on to the next “Anything But Carbon” explanation, I guess…
Hi Utahn,
Well, actually you are lucky. Here we love everybody, whether they like carbon or not. Not like other sites like Sceptical Science where they ban and censor people like me who dares to sing another tune,
like saying that more carbon dioxide is better….
Be blessed by knowing that driving a car (if you can still afford it) is good for the environment as it stimulates growth of more trees and greenery!
http://www.letterdash.com/HenryP/more-carbon-dioxide-is-ok-ok
“Here we love everybody, whether they like carbon or not. ”
Commenters, perhaps, posters, not so much, if the last 100 or so posts are representative.
I don´t know if this can breath a bit of life into the discussion, but I contacted Kevin Trenberth about Jens Raunsø Jensen´s, shall we say, unorthodox interpretation of Trenberth´s 1990 paper to support his thesis about ENSO being the main factor of the temperature rise in the last 50 years.
Let´s recapitulate: The issue is not whether ENSO is able to trigger sudden increases, or equally dramatic declines, in temperature from one year to another, e.g. like the 0,2C increase from 1995/96 to 1997/98. I think everybody agrees to this – this, per se, tells us nothing about the balance between different forcings over a timeframe as large as 50 years.
The issue is whether ENSO is likely or even able to generate some sort of new heating to the system in this process in order for the temperature to be able to increase by as much as 0,7C in 50 years – or at the very least, whether ENSO could be responsible for a larger fraction of this 0,7C than GHGs. This is what Jens Raunsø Jensen is implicitly or explicitly trying to make a case for.
I asked Trenberth:
and he replied:
So, just like the critics have asked all along: ENSO merely cyclically builds up heat but releases it again, and while ENSO could in theory have a residual heat build-up effect, there is no evidence for that.
To my mind, this also corresponds fine with the lack of trend – or at best, a weak insignificant one – in MEI over the last 40-50 years. Simply pointing at selected jumps and associate these with El Niño while failing to explain or even mention why the many other equally forceful La Niña apparently have not caused any cooling is deeply unscienfic.
Just to be absolutely clear, I furthermore asked:
and Trenberth replied:
[Italics mine, CBH]
Quite unequivocal, indeed. Not only has Jens Raunsø Jensen no physical support for this thesis, but his sources disavows his interpretation of their papers. This, to me, should settle the matter for now.
If Jens still thinks that he has a case, I think it is fair to say that he´ll need to show some pretty convincing evidence for this net buildup of heat in ENSO for his hypothesis to remain standing. It´s very fine to have an open mind, but to make new discoveries of permanent worth, one obviously needs some facts and some coherent hypotheses rooted in physical evidence, too.
Utahn says: Commenters, perhaps, posters, not so much, if the last 100 or so posts are representative.
Henry@Utahn
unfortunately this is the way it is.
there are certain sites that are pro-agw who adore you and ignore me (wipe me off)
and then there are sites who are not agw (new: acc)
they really don’t adore you or me but at least I find they don’t ignore you or me & they don’t wipe me off
Why don’t you study my findings and we can discuss it?
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
Look,
I am not putting down the writer of this article,
nor Christopher BH, nor Trenberth, etc
but if you look again here,
http://www.letterdash.com/HenryP/de-forestation-causes-cooling
you will find cooling in Argentinia due to de-forestation
(there is nothing else that I can think of that causes cooling, do you?)
and then look at the results from a weather station like Grootfontein, in Namibia,
you can view all my results here:
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
and then you read this:
http://wattsupwiththat.com/2011/03/24/the-earths-biosphere-is-booming-data-suggests-that-co2-is-the-cause-part-2/
If you have read the above post, you will note with me why I expected to find (some) warming in Grootfontein (Namibia) – I did select this station with a view to test a theory
tell me if anyone of you picked up on that clue
Christian Bugge Harder, Jan16 12:50am:
This is pathetic! In your obsessive persistence, you now misrepresent my post after having spent a considerable amount of time on abusive and ad hominem attacks in your previous comments. Are there no limits? I consider this a serious academic offence.
Just for the benefit of WUWT readers: I have no-where in my post “interpreted Trenberth (1990) to support my thesis of ENSO being the main factor about temperature rise in the last 50 years”, as you state in your opening paragraph. Also, I have not suggested that ENSO is “the main factor”, read my post. And I have only referred to Trenberth (1990) as a solid scientific reference on the regime shift in 1976/77. That’s all. Period. So I do quote Trenberth (1990) in context, contrary to your false accusation. And since you apparently have difficulty reading, I repeat: I have not used Trenberth (1990) to support any discussion on the mechanism. If you still think otherwise, provide the evidence with solid quotations from my post.
I think that you owe Trenberth an apology for trying to corner him into supporting your case by misrepresenting my position.
Another aspect that you are missing: the abrupt changes I have documented took place within 20 years (1977 – 1997), not the 40-50 years that you are claiming.
Your agenda is clearly not one of exploring the science with an open mind, and I do not intend to continue a dialogue on your premises.
Regards …. jens
jens,
IMHO, C.B. Harder is a very young and devious individual who shows up here occasionally to disseminate misinformation. The truth is not in him. There are many examples. Here is one from this article:
http://wattsupwiththat.com/2011/09/27/getting-grled
Poptech responded:
Harder simply fabricates things. It’s not worth arguing with someone who invents his ‘facts’ in order to win a debate that he would otherwise lose.