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Monckton misuses IPCC equation

What the science says...

Select a level... Intermediate Advanced

Lord Monckton has taken a single equation from the IPCC, used it in an inappropriate manner, and then attributed his results to the IPCC. This is as if I borrowed your car, drove into a tree, and then blamed you. He uses a method that is clearly intended to examine the long-term response of temperature to changes in carbon dioxide, and which is never used by the IPCC (nor should it be) to make predictions about current temperature trends. A slight change in Lord Monckton’s methodology as of July 2010 still does not make his method or attribution remotely appropriate.

Climate Myth...

IPCC overestimate temperature rise

"The IPCC’s predicted equilibrium warming path bears no relation to the far lesser rate of “global warming” that has been observed in the 21st century to date." (Christopher Monckton)

Monckton calculates his "predicted temperatures" using an equation found in the IPCC report (Working Group 3, Chapter 3) that is used to examine the long-term temperature response to carbon dioxide emissions: Teq = ECS × ln(CO2end / CO2start) / ln(2). This is essentially a ratio increase in CO2 multiplied by the equilibrium climate sensitivity (ECS), a value that represents how sensitive temperature is to changes in CO2. The IPCC gives the range for ECS of 2.0 to 4.5, with a "best estimate" of 3.0.

With this equation, Monckton uses the CO2 values from the IPCC’s A2 scenario: a CO2start value of 368 ppm in 2000 and a CO2end value of 836 ppm in 2100. He then examines the IPCC’s low- and high-end ECS values (2.0 and 4.5), but uses the "central estimate" of ECS = 3.25 instead of the IPCC’s "best estimate". Monckton has simplified the original equation by dividing ECS by ln(2) in order to provide a single multiplier. Here are the equations that produce the range of warming that Lord Monkton claims is predicted by the IPCC:

2.9 × ln(836/368) = 2.4 C
4.7 × ln(836/368) = 3.9 C
6.5 × ln(836/368) = 5.3 C

You can see that these values match up with the "IPCC predicts warming" values shown on Monckton’s figures.

There are four fundamental problems with using these values to "predict" temperatures and attributing them to the IPCC:

1. The IPCC does not "predict" anything on this matter – they make multiple projections assuming different future emissions scenarios. This may sound trivial, but it’s a very important distinction. Monckton narrows the analysis to a single scenario (A2) and labels it a prediction.

2. Temperature rise for the A2 scenario is very unlikely to be linear, and single values in °C / century are inappropriate when looking at temperatures for time periods of less than a century. This is particularly problematic when looking at very short time periods early in this century, which are likely to exhibit less warming than later in the century.

3. These equations predict the equilibrium temperature response, which is the final temperature change once the climate has fully adjusted to a change in CO2. It does not represent the temperature expected for the year that CO2 concentration reaches the value used in the equation (and will always be higher than this value). The IPCC is abundantly clear on this point.

4. The IPCC never uses or presents these values to project global temperatures in the first decade of the 21st century.

In his most recent figures from July 2010, Monckton has decided to address the fact that warming to equilibrium temperatures by 2100 is clearly wrong (fundamental problem #3). He does this by simply reducing equilibrium temperatures by one-fifth (or multiplying by 0.8) to convert to "transient warming", although it is unclear where he gets this conversion factor from. He has applied these changes to his "prediction zone" on the graph, but he has not changed the legend of the figure which still lists the incorrect equilibrium values after "IPCC predicts warming."

I was able to recreate Monckton’s July 2010 figure from scratch by plotting monthly temperatures as the average of the UAH and RSS satellite temperature values, and adjusting them like Monckton so that "the anomalies are zeroed to the least element in the dataset." I then plotted Monckton’s "transient" prediction zone using 3 lines with linear increases of 2.4 × 0.8 = 1.92 C/century, 3.9 × 0.8 = 3.12 C/century, and 5.3 × 0.8 = 4.24 C/century. I then zeroed the prediction zone "to the start-point of the least-squares linear-regression trend on the real-world data." Here is the result:

Figure 1: My reproduction and overlay of Monckton’s figure from his July 2010 SPPI report. (top) Monkton’s original figure; (middle) my reproduction; (bottom) overlay of the two. If anything, Monckton’s projection zones are slightly above the "transient" linear increases of 1.92 C/century, 3.12 C/century, and 4.24 C/century.

His prediction zones match up virtually perfectly to linear increases in temperature out to 2100 (highlighting fundamental problem #2). We can then extend these out to 2100 and examine whether Monckton’s warming rates in degrees per century match up with the actual IPCC projections:

Figure 2: Extensions of the "transient" linear warming paths from Figure 1, superimposed on the IPCC’s actual A2 temperature projection. Prediction zones were zeroed to the start of the Jan 2001 to July 2010 regression line of the UAH and RSS monthly average, using the base period of 1980-1999 to match the IPCC figure’s base period.

Monckton’s new transient warming zone aligns with the actual IPCC A2 projections quite well by 2100. However the problem with a linear temperature prediction is apparent (again, fundamental problem #2): Monckton’s transient warming path entirely excludes the bottom half of the IPCC projections until after 2030.

So as of his July 2010 report, Monckton’s prediction zones may have some relevance to temperatures at the end of the century (although they still suffer from fundamental problems #1 and #4 no matter what). However, they remain both inappropriate (fundamental problem #2) and deceptive (fundamental problems #1 and #4), when used for comparisons with recent observed temperatures. All of the prediction zones on his figures prior to July 2010 – including those shown in testimony to congress – suffer from all four fundamental problems. Just to highlight what a substantial issue fundamental problem #3 is, let’s examine the linear increase to 2100 based off of equilibrium warming:

Figure 3: The same as Figure 2, but using equilibrium linear warming paths.

Until Lord Monckton starts using the actual IPCC temperature projections and stops using climate sensitivity equations to "predict" temperatures from 2001 to 2010, his figures will be fundamentally flawed and unattributable to the IPCC.

- What about Monckton's CO2 predictions? -

Although, the primary topic here is Monckton’s "IPCC" temperature predictions, his "IPCC" CO2 predictions are also completely at odds with what is actually presented in the IPCC. Barry Bickmore from Brigham Young University has done an excellent bit of detective work to help elucidate the matter (see his RealClimate post here).

Dr. Bickmore compared Monckton’s "IPCC A2" CO2 values to the actual IPCC A2 CO2 values and found that, other than the start and end points, Monckton’s values are always higher. There is absolutely no justification for this. I’ve reproduced the same result by carefully scaling and overlaying Monckton’s graph onto the IPCC’s figure 10.20a (here’s an uncropped larger version):

Figure 4: Lord Monckton’s graph of the "IPCC’s predicted CO2" trend superimposed on the actual CO2 concentration trend from the IPCC’s figure 10.20a. Monckton’s "IPCC prediction" is clearly higher than the actual IPCC trend (which follows the observed values quite well).

- Additional figures -

Figure 5: The actual IPCC A2 temperature projection range (3-year running means) with observed global temperatures from the 5 major temperature analyses (36-month running means through June 2010).

Figure 6: Monckton’s "IPCC" temperature prediction from his July 2010 SPPI report compared to the actual IPCC A2 temperature projections.

Advanced rebuttal written by Alden Griffith

Update July 2015:

Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial

Last updated on 13 July 2015 by pattimer. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Argument Feedback

Please use this form to let us know about suggested updates to this rebuttal.

Notes from Alden Griffith

NOTE: this was originally posted by Alden Griffith at Fool Me Once as a video presentation. His notes also included the following notes:

- How did I digitize the IPCC A2 model projections? -

Because the figures in the IPCC's reports are largely vector graphics, it is possible to zoom in for great detail. I used Acrobat to copy individual lines as separate objects so that they could be digitized without overlapping. Once I had separately extracted all 17 lines, I digitized them into XY values by using GetData Graph Digitizer to trace each line at high resolution. I then used Matlab to interpolate the curves so that I could get values at the midpoint of each year as shown on the IPCC's figure.

- Additional resources -

John Abraham examines Lord Monckton’s many claims

Barry Bickmore investigates Monckton’s "IPCC" CO2 and temperature predictions
(see his own blog too)

Tim Lambert on Monckton’s 2010 testimony to Congress

- Special thanks to Jay Turner for his helpful comments and suggestions -


1  2  Next

Comments 1 to 50 out of 66:

  1. Wow! This SkS rebuttal topic really needs to be separated into Basic and Intermediate tabs! I am drowning in data. My quick reaction: 1. Too specific - replies only to Monckton's claim. 2. Too detailed - the uninitiated reader drowns. 3. Is it up-to-date? (No comments since Sep 2010?) What led me here was a perusal of that trouble-maker website Watts Up With That entry "The Skeptics Case". WUWT's article starts with very easy-to-understand color diagrams and follows up with graphs of IPCC temperature predictions vs. "measured temperatures". Does Skeptical Science have a rebuttal for this? Is this topic where the rebuttal should be?
  2. The WUWT "Skeptics Case" is written by Dr David M.W. Evans. It vividly compares "Predicted to actually measured" in Figure 3. But is that a fair summary? The Evans article is targeted to non-experts (like me), is well-written and has great graphics. Everything in it may be wrong or misleading, but it tells a convincing story.
  3. Tom - if you're specifically looking for comparisons between model temperature projections vs. observations (including by the IPCC), see the Lessons from Past Predictions series. As a general rule, if you see colorful easy-to-understand graphs on WUWT, you can bet the folks creating that graph have screwed up somehow. Evans for example cherrypicks data horribly, comparing surface temperature projections to atmospheric temperature measurements, and only looks at a few years of ocean heat content, and only of the shallow oceans, etc. etc.
  4. You're right that this rebuttal really should be updated though. I'll have to put that on my to-do list.
  5. I am slugging my way thru Alden Griffith's article & see the problem: It reads like a research paper. It is not a rebuttal for the benefit of the general public. While Griffith's work may be first-rate (I'm not qualified to judge), it doesn't seem to fit into the "mission" of Skeptical Science. Wouldn't one expect an overview that links off to a paper like this? Figure 4 has potential for mass-audiences, although it is very "busy". Hard to read the axes, and that thick red line at the bottom is confusing.
  6. Tom - sunlight reaching the Earth's surface dimmed during the period 2000-2007, yet the Earth continued to warm, albeit at a slower rate than the 1990's. More recent observations are not available, but the "global dimming" evident over this period, does partially explain the slowing of ocean heat uptake during 2003-2008 - especially as the dimming was principally a Southern Hemisphere phenomenon. The climate model projections which Evans "disses" do not factor in the global dimming trend through 2000-2007. A model hindcast using the actual surface solar radiation measurements to constrain it, would no doubt see a much closer agreement with the surface temperature measurements. In short; we would have expected a slowing in the rate of warming over that period. This is dealt with in upcoming posts, and rebuttals will be updated accordingly.
  7. Dana, I don't doubt for a second that WUWT and World Climate Report (WCR) publish flawed science and distort findings. That was obvious within a half-hour of browsing for even a relative amateur like myself. I'd like to see SkS Basic tabs effectively counter those pretty graphs and easy-to-understand slick words from WUWT and WCR that are quoted endlessly by Fox News and WSJ editorials. That may mean simplifying the Basic tabs and moving more precise stuff to Intermediate and Expert tabs. Rob Painting - Thanks! I'll be looking forward to the upcoming posts and rebuttals.
  8. Just out of curiosity, how do you "adjust" the IPCC's predictions to reflect observed GHG forcings? Because it seems as though there's a big difference between doing that (which results in the images shown above) and not doing it (which results in images like the one below). This graph shows the IPCC's supposed

    In other words, what's wrong with this picture?

    Also, I hate to sound like a broken record (as I said this about the "Southern sea ice is increasing" page too), but I don't see why we need both this page and the one called "IPCC global warming projections were wrong," as they both seem to cover the same topic.


    [Dikran Marsupial] Please can you limit your images to no more than 500 pixels wide.  I have made the adjustment this time.

  9. jsmith, the image you have shown there is not actually "unadjusted".  The model projections used in the 1990 IPCC report do not all agree exactly on the temperature in 1990, and they definitely didn't predict the observations exactly either.  The thing that is wrong with the picture is that they have used a baseline of year (whci happened to be a peak in the observations), rather than the proper procedure of a 30 year baseline.  The problem with a single year baseline is that you can make it give any result you want, you can make it look like the models over-predict temperatures by baselining to a warm year, or you can make them look as if they are running cooler by baselining to a cold year.  Sadly this sort of thing is done all the time, but that doesn't mean that it is correct - far from it.

  10. Here is an example of what I mean (vai

    Here I've shown the HADCRUT4 datase, along with two lines representing completely accurate representations of the rate of warming, but only differing in the vertical offset introduced by the choice of baseline year. 

    The green line represents a "skeptics" presentation, where the observations and projection were baselined to a peak in the observations so that the observations are then generally below the projection.  "IPCC models over predict warming" is the headline.

    The blue line represents an "alarmist" presentation, where the observations and projections were baselined to a trough in the observations, so that the observations are generally higher than the projection.  "IPCC models underpredict warming" is the headline.

    The magenta line represents the scientific presentation (in this case it is just the OLS trend line), where the offset hasn't been cherry picked to support the desired argument.

  11. Just to further clarify DM...

    You can't do this (red circle):

    That is a single year, cherry picked, baseline. It's something you see Chris Monckton constantly doing in his presentations.

  12. BTW a later article by Monckton (2012) does another odd thing with IPCC projections, based purely on arithmetic.  The final comment there is mine and intended to be read side-by-side with the article.  It took some time to work out what Monckton was doing, which was back-projecting the same figures from the projections to obtain estimates for warming in 1960-2008, first assuming the CO₂-temp relationship was logarithmic, secondly that it was linear.  Unsurprisingly he finds a discrepancy between those two results, but he assumes that is a flaw in the models (!).

    I didn't start from an ad hominem premise, but can't help trying to understand what was driving Monckton in that article.  In the Meet the Sceptics (2011) documentary, he claims to have cured himself of Graves' disease.  As I understand it, mental confusion is an occasional symptom of hyperthyroidism.  I don't mean that gives additional reason to dismiss his varied claims, but it might invite a more sympathetic response.

  13. I don't know why this is not in the top ten.  I hear this all the time.

  14. If JSmith's methods were wrong can you not at least address his core concern? Your article doesn't show the actual IPCC first assessment predictions for temperature, but adjusts them prior to comparison to observed temperature. The IPCC first assessment summary states in Chapter 6 that for 2030 they see "a predicted rise trom 1990 of 0.7-1.5°C with a best estimate of 1.1C". If I'm not mistaken, we currently are very much on track to be under 1.1C warmer than 1990 in the next 15 years?

    If JSmith made mistakes or inaccuracies in matching the observed temperatures to the 1990 IPCC predictions as they were published below, don't just settle for saying he did it wrong. Graph the actual observed temperatures against the actual published predictions of the IPCC from 1990 as shown below. I'm afraid all my efforts to match recorded observations to them only seem close to matching the very coldest 1990 predictions and I'd love to see a graph that can more clearly show me where I'm going wrong.

    IPCC First Assessment Fig 6.11

  15. bcglrofindel - In short, short term variability. GCMs are intended to project (not predict) average climate over the long term, and there has never been a claim that they could accurately predict short term variations that cancel out over several decades. 

    See this post examining how recent short term variations have affected longer term projections. Or this thread comparing various projections (including 'skeptic' ones) against actual temperatures, although that only goes to 2011.

    Various projections, good and bad

    Quite frankly, even the earliest IPCC projections are quite good. Certainly when compared to those from people in denial of climate science...

  16. KR,

    You still aren't giving a simple apples to apples comparison. The claim I see people making is that the published IPCC trends from 1990 are too high compared to actual measured temperature. Isn't it trivial to plot actual temperature against the 3 projections the IPCC gave in Fig 6.11? That would easily do away with all the hedging and confusion and end the matter, no? Why can't I find such a simple plot anywhere? All the places I find such a plot, like JSmith's in thread, it's called out as inaccurate. Can't 3 simple plots done on excel in about a half hour clear this up and silence skeptics?

  17. bcglrofindel:

    I can't sort through just exactly what your issue is with the IPCC projections. To begin with, exactly which projection are you selecting, why are you selecting that one, and what data are you using to compare?

    Each IPCC projection has some assumptions in it, with respect to the growth of atmospheric CO2 (emissions scenario) and the temperature response to that change in CO2 (climate sensitivity).

    With four emissions scenarios and three climate sensitivty values, that gives 12 projections "on display". Note that these projections are not "predictions", because the IPCC is not claiming that one (or any) of these is "the one". When comparing to observations (i.e., testing the projections as if they were predictions), you have to do the following:

    • if one of the 12 scenarios is a good match choose it
    • if none match well, adjust the results from the projections to take into account the difference in assumptions - i.e., interpolate or extrapolate from the published scenario results.

    Note that the choice of an approriate scenario is based on the closeness of the assumptions, not the closeness of the temperature trend.

    Let's take a trivial model as an example. Let's assume that we have a linear model that states:

    T = A + B*CO2(t)

    where T is temperature at time t, as a function of the concentration of CO2 at time t (CO2(t)), and A and B are parameters. If I want to make a projection (not a prediction) of temperature into the future, I need three things:

    1. I need a scenario to tell me the value of CO2(t).
    2. I need the sensitivity parameter B (the slope, in linear-equation-speak)
    3. I need the inital value A (the intercept, in linear-equation-speak)

    I will have uncertainties in my CO2(t) values, and in my sensitivity B. As a good scientist, I will try several values of each, based on my understanding of what is reasonable or possible, and I will publish results of those several projections. This is what the IPCC did (with models a little more complex than the linear example here!).

    Now, after several years, I want to compare the actual observed T to my model results. I need to determine:

    • did one of my CO2(t) assumptions fit reality?
    • do I have any better information to tell me what value of B is best?

    ...and, most importantly...

    • what is an appropriate value of A to use to start things off?

    Once I have all that, I can start to compare the model to observations. I may need a new CO2(t) time series, and I may need to use different values of A and B from my earlier projections. Note that this does not mean that I'm changing my model: I'm just changing input parameters.


    jsmith's graph has the mistake of choosing an inappropriate value for A. The observations contain a lot of "noise", which causes annual variation that is not a function of CO2 concentration. If jsmith's graph were repeated using 1992 as a starting point, the results would be very different. This lack of a robust result ("robust" means that the analysis is not highly dependent on a particular assumption) is an indication that the result is unreliable. This is what Dikran points out in comment #10.

    By contrast, if you averaged observations over several years and matched that to the average of the model over the same years, and used that to determine the value of A, you would likely discover that the value of A did not change much if you chose different periods (near the start of the comparison). This would be a robust result, because you could say "I chose this period, but the results are pretty much the same if I choose another period".

  18. I wa referring to the temperature projections from the IPCC first assessment report, Chapter 6. In Figure 6.11 they have 3 graphs for three different temperature sensitivities. It's also notably the ONLY temperature predictions posted in the first assessment report, isn't it? I'll post the image a second time below. What I am told is that actual instrumental temperatures are colder than all of the predictions in Fig 6.11 from the IPCC F(irst)AR. Can someone not simply graph instrumental temperatures against the IPCC projections below and demonstrate the truth? Shouldn't it be a simple enough task? Unfortunately the only examples I can find are like JSmith's that are declared inaccurate.


    IPCC FAR 1990

  19. Maybe more simply, I want to add the red line below where the red line is actual instrumental temperature record:


    IPCC plus wished for Instrumental

  20. bcglrofindel - You certainly can find such a plot. I would suggest looking at the AR5 Technical Summary, in particular Fig. TFE.3:

    Up through AR4

    AR5 Projections


    JSmith's graph suffers from selecting a single timepoint offset, rather than a multi-year average that cancels out short-term variations, and hence is a misleading presentation. 

  21. Thanks KR, my trouble is still actually seeing what the FAR range actually is on that graph. I've hunted around for the actual underlying data for the graph but can't find it anywhere. Regrettably, the shading of all 4 AR onto the same graph leaves the FAR virtually completely hidden for the entire time the instrumental record is plotted :(.

  22. bcglrofindel - I would have to agree that the chart is quite difficult to parse. But that's not uncommon when overlaying so much data, and frankly the TAR/SAR/FAR models and projections, while interesting as historical documents, are far from state of the art in resolution, in incorporated components of the climate, and perhaps most importantly in the more recent forcing histories.

    Hence, while I personally would have preferred to have just the overlaid ranges and not individual model runs plotted there, I'm not surprised that AR5 spent very little time and graph space on the previous reports. 

  23. " Isn't it trivial to plot actual temperature against the 3 projections the IPCC gave in Fig 6.11?"

    But doing that comparison would be falling for a straw man fallacy. The IPCC does NOT predict that actual measured temperatures will follow those lines. However, it would expect 30-year trends to follow those lines. It is interesting that skeptic make dance that actual temperature is below ensemble mean (its natural variation), but werent worried when in earlier decades suface temps were running hotter (also natural variation). Trends in surface temp shorter than 30 year are weather not climate.

  24. bcglrofindel:

    1)  In the estimates made using the energy balance diffusive model, the IPCC assumed a radiative forcing for doubled CO2 of 4 W/m^2 rather than the actual 3.7 W/m^2.  The more accurate value was determined by Myhre et al (1998), and included in IPCC reports since the Third Assessment Report (2001).

    2)  The radiative forcing for the BAU scenario in 2015 for the energy balance diffusive model of IPCC FAR was 4 W/m^2 (Figure 6, Policy Makers Summary, IPCC FAR).  For comparison, the current radiative forcing is 3 W/m^2 (IPCC AR4 Technical Summary, Table TS.7), 25% less.  To properly test the actual model used in making the predictions, you would need to run the model with accurate forcings.  An approximation of the prediction can be made by simply scaling the values, so that the IPCC 2030 predictions would be 0.83 C (0.53-1.13 C).

    3)  The reasons for the high value of the projected BAU forcings are:

    a)  The high estimate of radiative forcing for a doubled CO2 concentration already mentioned;

    b)  The fact that the model did not project future temperature changes; but the effect on future temperature changes based on changes in GHGs alone; and

    c)  A failure to predict the break up of the former Soviet Union, and the consequent massive reduction in emissions growth.

    Factors (a) and (c) explain the discrepancy between the projected BAU forcing for GHG alone (4 W/m^2 for 2015) and the current observed forcing for GHG alone (3.03 W/m^2).  From that, it is easy to calculate that there is a 16.75% reduction in expected (BAU) forcing due to reduced industry in the former Soviet Block (plus unexpectedly rapid reduction in HFC's due to the Montreal Protocol).

    Thus insisting on a comparison of the actual temperature trend to the actual BAU projections in order to determine the accuracy of the model used by IPCC FAR amounts to the assumption that:

    A)  The IPCC intended the projections as projections of actual temperature changes rather than projections of the expected influence of greenhouse gases, contrary to the explicity statement of the IPCC FAR;

    B)  The IPCC should be criticized based on their use of the best current science rather than the scientific knowledge gained 8 years after publication, and 16 years prior to the current criticism (Myhre et al, 98); and

    C)  The failure of the IPCC to project the break up of the Soviet Union invalidates its global climate models.

    The last leaves me laughing.  I look forward to your produceing quotes from the critics of the IPCC dated 1990 or earlier predicting both the break up of the Soviet Union and a huge reduction in CO2 emissions as a result to show that they were wise before the event.  Better yet would be their statements to that effect in peer reviewed literature so that the IPCC can be shown to be negligent in not noting their opinion.  I expect confidently zero evidence of either (due to their not existing).

    I am also looking forward to your defence of those three assumptions, as you seem to consider the direct comparison (rather than a comparison with the forcings of the model adjusted to observed values) to be significant.  Failing that defence, or your acknowledgement that the assumptions are not only invalid but unreasonable, I will consider you to be deliberately raising a strawman.

    4)  Despite those issues, the 30 year trend to 2013 of the GISS temperature series is 0.171 C per decade, just shy of the 0.175 C per decade for the lower value.  That it is just shy is entirely due to short term variation due to ENSO.  The 30 year trend to 2007, for example is 0.184 C per decade, just above the lower limit.  Further, that is a misleading comparison in that it treats the trend as linear, wheras it the projection in fact accelerates (ie, we expect a lower than 0.175 C trend in the first half of the period).  Ergo, not withstanding all the points raised above, the IPCC FAR projections have not in fact been falsified - even without adjustments to use historical forcing data, and even ignoring the fact that it was not intended as a projection of future temperatures (but only of the GHG impact on future temperatures).

  25. Tom Curtis - Note that bcglrofindel didn't insist that modeling was invalidated by differences between past projections of climate versus emission expectations, but presented a query as to why a simple comparison might look off. While there are a lot of climate trollers who pass by, I would prefer to treat everyone as sincerely interested in a discussion unless/until proven otherwise.

  26. KR @25, I have not assumed bcglrofindel does not have valid concerns.  I have addressed his concerns by showing why a direct comparison is simply misleading (on numerous grounds).  He is quite welcome to respond by showing that he now gets why it is inappropriate.  

  27. A word to bcglrofindel, who I hope is still following this thread:

    One of the SkS comments policies is "no dog-piling", which is intended to avoid having one poster have to deal with a whole bunch of comments from several people. It can be overwhelming.

    In this thread, you've now had several people respond. In your last comment @21, you indicated that you still inidcate a desire for a simple graph, even though there have been several comments saying why this is difficult - some directed to you, some in response to jsmith's earlier graph.

    If you still can't see why the graph jsmith provided is misleading, it would help if you told us why you feel that the responses don't explain it well. Please engage in a conversation about these explanations. If the number of responses is too much for the moment, tell us that you wish to discuss one aspect of things, and engage on that aspect. Refrain from introducing new issues until the discussion on that aspect is complete.

    Regulars here wil lose patience if they feel that their responses are being ignored. A simple acknowledgement of "OK, I see that now" (as suggested by Tom @ 26), will go a long way in terms of encouraging a productive discussion.

  28. @Bob Loblaw,

    Thanks for that. I'm Canadian and so yesterday was remembrance day and thus I was out visiting family and not back in till now.

    My background is comp sci, so I very much understand that the original FAR models assumptions matter to the results they plotted and if scenario baseline assumptions aren't met that results will differ. I agree with all of that as self evident. It's also IMHO a very big and broad subject to try and get into.

    My question that I still only have a fuzzy yes/maybe/no answer to is about how actual measured temperature compares to the published FAR temperature projections in Fig6.11. I totally understand that those projections had massive spreads within themselves because of the broad number of scenarios and unkowables they were working from. That doesn't stop people I've seen from posting the claim that ALL the FAR Fig6.11 projections are higher than current actual temperatures. I don't have a problem articulating the reasons that would be 'ok' or not a disprove of underlying theory. I can argue for and against that well enough. What I don't know is if that base claim is even remotely true. The best I can do is try and see from the graphs in Fig6.11 what temp increase from 1990 through 2014 the graphs show, which is extremely rough and not in anyway pursuasive. Additionally, if anyone has access somewhere to the actual raw data used for Fig6.11, then it should be trivial to show how actual temperature has tracked to the Fig6.11 scenarios, no? Yes, I know the scenarios Fig6.11 used with radically high assumptions will be too high, and we all know to expect that. I just want to know if people that claim all scenarios in Fig6.11 exceed modern temp can be called liars? More over, if I call them liars, am I actually the one lying?

  29. scaddenp,

    We are talking about the 1990 IPCC report, so the current record is about 25 years out and closing on the 30 years you suggest quickly. I also don't think it's the best argument to just tell people well the answer doesn't matter, or is just a strawman. The IPCC temperature projections ARE described in th executive summary as BEST guess changes. The IPCC executive summary IS being used to inform policy changes. When I see someone claiming that the IPCC temperature projections, in ALL scenarios, estimated higher actual temperatures than we see today on actual record I don't feel like telling them it's irrelevant is a strong argument.

    More over, my underlying and overarching question was if there is anywhere one can simply go to point out the truth or falsity of such a claim? We have the instrumental temperature record available all over the place online, but referencing it correctly to the IPCC FAR fig6.11 is tricky without the actual data underlying the FAR projections.


    My question more simply is if someone claims that the IPCC F(irst)AR overestimated temeprature compared to actual measurements are they making a false statement? If I say that isn't true, am I lying?

  30. Tom Curtis,

    I believe responses like yours just drives away skeptics. A question as simple as how do the IPCC projections from 1990 compare to the instrumental record today nearly 25 years later seems a fairly honest starting point. To summarize the correct response to such a query as declaring the very question as "inappropriate" is terrible.

    IMHO, the correct responses are one of:

    The actual is hotter, and here is why.

    The actual is cooler, and here is why.

    The actual is very close, and here is why.

  31. bcglrofindel,

    I don't have precise data for the answer you want, but would make some points:

    (1) el Nino / la Nina phase correlates highly with internal (ie not externally or CO2 driven) temperature variability, and we are currently in a highly el Nino negative period, which therefore would be expected to be unusually cooler than the projections. However there are forcings  over the last 10 years (TSI, aerosols) which affect the temperature so I am not sure how dominant this effect is.

    (2) I can't give an immediate answer because the correct projection needs to be chosen for CO2 emissions. This does not require much work. 

    (3) A straight comparison should be doable, as long as careful attention is paid to baselining, and result in a deviation explainable to some extent by variability in aerosols (volcanic and anthropogenic), TSI. The rest will be internal variation (of which the el Nino/la Nina phase is an important component) and errors in the 1990 model assumptions or input data.

    I'd like to see the answer but am not in a position myself to provide it. I wonder if a web search would find something?

    One point to remember is that all of the un-modelled variability noted above is highly significant - so that we expect the actual temperature to depart a lot from the model average (which is what you see in the graphs). And that the actual temperature represents one run of a model, so that it is much more variable than the variation in model averages.

    Another related point is that in doing these comparisons you need to be really careful about (for example) baselining. There is so much decadal randomness that small changes in even quite a long baseline can make a big difference.

    You will see that the above is explaining my inability to give a simple answer such as you ask without lots of ifs an buts. Sometimes life is like that! Perhaps somone else can link to a reasonably complete study?

  32. tom_clarke, thanks.

    A websearch for that kind of data is what ended up bringing me to this article :). I again appreciate the very great degree of variability there is in projections. The FAR folks did up three separate graphs for CO2 doubling sensitivity of 4.5, 2.5 and 1.5. Then, within each graph they also included 4 different emissions scenarios. I appreciate that leaves lots of room to fall outside the modelled scenarios. At the same time, I don't especially like going overboard in declaring that the entirety of all the scenarios projected by the FAR folks were all to pessimistic. That just about leads to a "told ya so" from the ones claiming the FAR projections are all too hot compared to instrumental records. 

    IMO, the big problem here is trust and confidence in modelling. Hindcasting accuracy doesn't exactly resonate with a skeptical audience as proof positive. Projections like the FAR that are 25 years old though are pretty powerfull. It's hard to 'fake' getting good results 25 years later. It's also necessary to explaing bad results 25 years later.

    That said though, I'm still at the stage of answering the question of whether the projections have yielded good, bad or in between results 25 years later. The graph would seem a simple endeavour. I've tried digitizing data points from Fig6.11 below for sensitivity of 1.5, the coldest, but with emission scenario Business as Usual(the most pessimistic). By digitizing though I mean zooming tight on the image and drawing my own graph lines across to attempt to get close numbers:

    1962 - 0.375

    1963 - 0.375

    1975 - 0.49

    1987 - 0.625

    1988 - 0.625

    2000 - 0.75

    2012 - 0.875

    2013 - 0.875


  33. "We are talking about the 1990 IPCC report, so the current record is about 25 years out and closing on the 30 years you suggest quickly."

    Yes, but it seems you are trying to compare a point - the temperature today - with a position on the curve which is not valid. You can compare the 30 year average with the projected 30 year average. To do otherwise means you are forever wrong - "+ve esno cycle - the models are underpredicting", oops, "-ve cycle. the models are too hot". What the models to do not pretend to do, is predict enso variability and any comparison that do not allow for that is invalid.

  34. bcglrofindel - If you recall, I gave you a graph of temperatures vs. projections earlier in the thread, including the 1990 FAR. More specifically in the collection of SkS threads examining past projections is a direct FAR comparison here:

    FAR vs. observations


    Far more relevant are FAR models using actual greenhouse emissions to present (which didn't exactly match any of the scenarios), as the various scenarios were just that, scenarios, not looking-glass prophetic visions of future economies:

    FAR with observed GHG concentrations

    The FAR models were quite simple - but all in all did a reasonable job. 

    In short: The FAR projections were not exact matches to observed history, but the models they used appear to be in the right range for predicting trends vs. GHG emissions.

    "...had the IPCC FAR correctly projected the changes in atmospheric GHG from 1990 to 2011, their "best estimate" model with a 2.5°C equilibrium climate sensitivity would have projected the ensuing global warming very accurately"

    I believe that is a sufficient response for the naysayers. 

  35. bcglrofindel @ 30, no!  Responses like mine may drive away deniers, ie, pseudo-skeptics who want to generate a talking point without understanding it.  Genuine skeptics, however, are only interested in apples to apples comparisons.  If the IPCC plotted only the expected temperature increase due to green house gases (and did not include the temperature decrease due to aersols), they will want to know that, and want to plot "the temperature increase due to GHG" against the IPCC projections (and will note, unfortunately that no thermometers are only able to distinguish temperature changes due to greenhouse gases).  Alternatively, they will want to plot the actual temperature increase against either the IPCC FAR projections adjusted to match the actual change in forcing, or against that scenario which most closely matches the actual change in forcings (scenario B for overall forcings).  Further, they will want the reasons for those particular comparisons discussed rather than being presented with an unexplained graph that will only mislead the unwary.

    Despite this, you persist in wanting a temperature comparison with the BAU projections despite the known fact that emmissions did not follow the BAU scenario, and the change in forcing between 1990 and 2011 matches the much lower value of scenario B.

  36. It's very important to remember that the scenario projections _are not predictions_! The only 'prediction'(more correctly a conclusion) from the climate model is that of the _relationship_ between emissions and climate change. The only appropriate test is to examine whether the relationship embodied in the physics of the models holds between actual emissions and observed temperatures, not between observations from actual emissions and 'what if' scenarios with wholly different GHG histories.

    Complaining about a mismatch between observations and model projections from scenarios that didn't occur, as is so common from 'skeptics', is nothing more than a strawman argument, a logical fallacy.

  37. As a followup to KR's last sentence, you can get a look at what a pseudo-skeptic does with this comparison by looking at this Skeptical Science post about Pat Michaels.

  38. @KR thanks, the graph there is pretty much exactly what I was wanting to track down. When it was in the gif with a dozen other graphs I failed to pick it out specifically.

    @Tom Curtis, I understand being enthusiastic when you are passionate about something, but your posts are all coming across way overly aggressive. So much so you don't really even seem to have bothered with reading my actual requests as I never insisted on the BAU scenario comparison, but just any comparison to the entirety of the scenarios used in the FAR including bau, b, c, and d. 


    IMHO I don't quite agree with the vehement insistance on rejecting the initial query itself. KR's second last post and in particular his source are pretty much exactly what I was looking for from the start. I hadn't thought I'd asked the question that badly? The extensive insistence that we should discourage people from making the query at all, and even further should be shaming them for asking it is, well, wrong. That approach is going to just drive away most people and as likely as not they'll take the extreme defensiveness as proof the claim is true. Meanwhile, the reality is that plotting temp against the FAR scenarios places reality having fallen HOTTER hotter than FAR BAU at 1.5 sensitivity.

    Additionally, insisting that under NO CIRCUMSTANCES no circumstances was reality anywhere near even the most optimistic of the FAR's assumptions and scenarios is basically telling a skeptic they were right all along, and exactly the OPPOSITE opposite tactic I'd think should be taken. 

    Sorry, I don't want to be hyper critical, and doubly so with a good answer to my query in hand. I do however find the extraordinary grilling and condmening of the query as counter productive and frankly damaging and really want to put that out there as something to be cautioned against.


    [JH] The use of "all caps" is akin to shouting and is prohibited by SkS Comments Policy

  39. bcglrofindel - I had forgotten about that earlier FAR specific post; SkS really contains a lot of information. If you're interested in other predictions that have been examined here, the Lessons from Predictions button in the left margin is quite useful. 

    I'm afraid that much of the strength of the reaction to your questions was based on past experiences - I cannot count how many times someone has commented here and on other climate blogs claiming despite the evidence that mismatches between specific projections and observed temperatures somehow invalidate all climate modeling, despite the projected emissions not matching actuals. The pattern for those 'skeptics' is one of starting out with what sems like a reasonable question, then not accepting the explanations, degenerating into denial, libertarian fantasies, and conspiracy theories while asserting counterfactuals, before their politeness finally expires and moderation kicks in. But it's difficult to distinguish between such people and the genuinely curious early in the exchange. 

    Note to everyone - As bcglrofindel points out, such a strong reaction can be quite offputting. Save the sarcasm for people who have demonstrated the need for heavy implements in clue delivery. 

  40. bcglrofindel I think perhaps it would be a good thing if you were to review the wording of your initial posts here in understanding the reception you have received.   jsmith wanted asked a question about why the adjustments made such a large difference compared to the diagram that he introduced into the discussion.  It was explained why that diagram was itself highly nuanced (the nuance explaining a lot of the difference).  Your first comment began

    "If JSmith's methods were wrong can you not at least address his core concern? "

    Note that you implicitly question the issues that I had raised (or at least do not accept them), but if his core concern was indeed the discrepancy, then the issue that I had raised explains most of it.  You began on this thread by effectively glossing over a substantive issue that had been raised.  That is not conducive to scientific discussion.

    KR then made the very important point that GCM projections are not intended to be accurate over such short timescales, and gave an appropriate plot of various projections to demonstrate this, but your reply was frankly rather rude "You still aren't giving a simple apples to apples comparison." and went on to ask " Isn't it trivial to plot actual temperature against the 3 projections the IPCC gave in Fig 6.11? "

    the answer to this is that "yes it would be trivial, but it would be misleading for the reasons that had already been explained to you, for a start it is important to take into account that the observed forcings did not match those used in the scenarios, so you should adjust for that in order to make a like-for-like comparison"

    however you write "That would easily do away with all the hedging and confusion and end the matter, no? "

    now "hedging" suggests that someone is being deliberately disingenuous in their presentation of the data.  Getting the science right, and adjusting for known problems is not "hedging".

    Can you see that your own comments here have not been altogether conducive to good natured discussion.

    you carry on

    "Why can't I find such a simple plot anywhere? All the places I find such a plot, like JSmith's in thread, it's called out as inaccurate. Can't 3 simple plots done on excel in about a half hour clear this up and silence skeptics?"

    I explained why JSmiths plot is problematic (I wouldn't say innacurate, just that there are nuances in its interpretation that you need to be aware of).  Now accepting my criticism would be fine, or challenging it, that would be fine to.  However you chose a third option, which was to imply that it was some sort of partisan rejection.  I find that kind of treatment of my well-intentioned comments to be pretty offensive.  However, that is pretty much water of a ducks back these days, so I let it go; others may not have been that charitable.

    I suspect that part of the problem here is that the issue is not as straightforward as you think it ought to be, and you are having difficulty accepting that others know more than you do about this.  Hopefully this will help you see why you have had the reception you have recieved, it is at least partly your own fault.

    In short, it is better to ask questions with some humility, and if you don't understand why something is not done the way you think it should be done, consider that there may be good reasons and ask why, rather than demand plots being drawn to your specifications.

  41. incidentally, it is pretty well known that electronic forms of communication have a tendency to be percieved as being rather more agressive than actually intended, which I think applies to all sides in this discussion.  Note my previous comment was intended as helpful guidance for bcglrofindel on adjusting his posting style to be a little less confrontational, and hence improve his/her interaction here.

  42. bcglorfindel wrote "IMO, the big problem here is trust and confidence in modelling."

    The graph you propose will not be able to address this question in a scientific manner because projections tend to have stated uncertainties, as do the observations, so you would need to add credible intervals to both before you could really determine whether the models had peformed as well as could be reasonably expected over such a short timescale.

    Another important point to bear in mind (and this is really important) which is the mean of an ensemble of model runs is not a projection of the trajectory of the Earth's actual climate, just of theofirced component (i.e. the climate change that results from a change in the forcings, rather than sources of internal climate variability).  A fairer comparsion would involve also adjusting the observations to account for the effects of internal variablity (e.g. by regression analysis to remove the effects of ENSO and volcanic forcings which the models do not include).

    Performing an apples-v-apples comparsion is not as straightforward as you might think, and performing the comparison properly includes either performing the adjustments to the best of your ability or including the caveats that explain (if not quantify) likely sources of discrepancy.

  43. Given bcglrofindel's comments @38, I am tempted to let him totter of with his stick to the gun fight.  However ...

    While the two graphs shown by KR @34 are excellent for their purpose, that purpose is not the comparison of post 1990s trends.  As the comparison of temperature changes post 1990 is the "purpose" of the pseudo-skeptical interest in the FAR projections, the graphs are not suitable for the underlying purpose.  Used as such, a competent* pseudo-skeptic will point out that:

    1)  The graph shows a multi year average of the GISS temperature record, thereby eliminating (by regression to the mean) some of the lower temperature values in the twenty first century;

    2)  The graph has no clearly defined baselining procedure (and natural candidates are excluded by relative values); and (most importantly)

    3)  By taking the change in temperautre from 1880, the graph allows the accumulated relative difference over 110 years to distract from the very different rates of change between observations and IPCC FAR projections post 1990 (and particularly post 2000).

    Please note that these are only problems when the graphs are used, contrary to their original purpose, to compare changes in temperature post 1990.  Further, note that, with regard to point (2), although the baselining method is not specified, a perfectly valid baselining technique may have been used (and probably was given that Dana constructed the graph).  However, if you do not know what it is, you cannot defend its reasonableness, or correct for it if you think it unreasonable.

    Because the graphs are not suitable for comparison of post 1990 changes in temperature, the original article included a graph for just that purpose:


    Note, however, that for that graph, the IPCC "projection" was adjusted to reflect actual (rather than projected) changes in GHG forcings.

    So, once again we return to the same points.  A proper comparison requires understanding the difference between projections and predictions, and not expecting the IPCC to "predict" the fall of the former Soviet Union (among other things).


    (* The incompetent pseudo-skeptics tend to simply reject such graphs out of hand on the sole basis that they come from Skeptical Science.)

  44. bcgirofindel @38.

    Your original comment here talked of JSmith making "mistakes or inaccuracies in matching" data. But JSmith did no matching. Rather, he simply cut and pasted a graphic sourced from the internet, a graphic which originated as part of a piece of denialistic reporting by Der Spiegel.

    And I'm still at a loss as to why the "simple apples to apples comparison" called for would require to be with the IPCC FAR graphics rather than the IPCC FAR calculations. Surely we wish to judge the IPCC on the veracity of its calculations not on its abilities in accurately predicting the future w.r.t. such things as the speed with which CFCs would be phased out, the drop in methane emissions from waste tips and petrochemicals, the collapse of Communism, etc.

  45. @Dikran and Tom

    If I'd been able to find or see the original source reference to this graph of temp vs. FAR I'd not even have posted as my query was answered:

    FAR vs Actual


    What I read and could see instead was no mention of how actual temperature compared to the FAR because that was declared misleading, unscientific, etc. JSmith attempted his own graph of same, and it was pointed out that his actual was grossly inaccurate and nothing like what an honest plot of actual vs FAR would look like. However, there was still lack of any plotting of what that different honest FAR vs actual would look like. As it turns out, a separate page on this very site had exactly that graph as linked above. Better still before KR kindly pointed to that graph, I had broken down and endeavoured to digitize the FAR graphs myself and reference temperature trends over the period prior to 1985 from the FAR graphs. Averaging across that time frame, I get the encouraging reward of a near matching to the result of above pre-existing graph. 

    The only thing I guess I really have left to say is that I don't count that as trivial, dishonest or entirely without value. I still staunchly disagree that looking for that result is inherently dishonest, or even misguided.

    The Joe Blow public wants simple tests that lack lengthy qualifications and caveats. The IPCC team that worked on FAR understood that, and half their reason to exist was to endeavor to bridge that gap. To that end, the projections they did included considerations for a broad range of possible unknowns. A key reason for doing this is to span the spectrum of possible future outcomes. Discount their efforts to that at your peril. The CO2 sensitivity ranges they used spanned from 1.5 to 4.5, which if I'm not mistaken is still within the currently expected range? The atmospheric CO2 and CO2 equivalent concentrations they used in scenarios BAU, B, C, D still span the current day values. If I'm not mistaken, falling inbetween BAU and B?

    If you start denying those basic coverages, you're discrediting the FAR report and work for any skeptics. They'll just throw your claims right bakc in your face and say see, told ya so. As you've admitted, the IPCC so misjudged climate conditions 25 years later that not even it's defenders expect it to be correct.

    Meanwhile there exists the graph I've included showing a tracking of actual temp to IPCC predictions from 25 years ago with the actual temp between the IPCC worst and best scenario estimates. Yes, there are plenty of caveats to be included, but simple is better. Certainly better than throwing the entire IPCC FAR team under the bus for no good reason.

  46. bcglrofindel @45.

    "The atmospheric CO2 and CO2 equivalent concentrations they used in scenarios BAU, B, C, D still span the current day values. If I'm not mistaken, falling inbetween BAU and B?"

    You are mistaken. For instance, compare the total of equivilant values in AR5 Table AII.2 for AD2000 with those in  FAR Table 2.7. AR5 forcings lie below all values used by FAR.

  47. "The only thing I guess I really have left to say is that I don't count that as trivial, dishonest or entirely without value."

    IF you conclude from the comparison that the underlying physical model is useless, you are in fact wrong.  That is all anyone is saying.  The physical model works OK IF the forcings are correct and you use a proper baseline. More recent models do better, and capture a lot more of the natural variability, so the focus on FAR escapes me.

    In that light, the comparison in the figure is only really useful to show that it is hard to predict volcanoes, economic and political crises, management decisions, and technological changes that might influence the forcings. But that point is really quite trivial, and is the whole point behind using different scenarios, as you point out.

    You must realize that people use the mismatches that stem from the second problem to imply that the first problem is serious, when an appropriate comparison would indicate that the physical model works prety well. They don't always make that argument sincerely, but sometimes they just don't know better.  If you go into a discussion not realizing that, you will be unpleasantly surprised by the result.

  48. A not-so-trivial note here: the 1990 FAR models used a direct forcing of CO2 simplified equation of 6.3*ln(C/C0) (see pg. 52 of the FAR Radiative Focing document), while later literature in particular Myhre et al 1998 using improved spectra computed a direct CO2 forcing of 5.35*ln(C/C0), changing that direct CO2 forcing estimate from 4.37 W/m2 to 3.7 W/m2. N2O and CFC simplified values were also updated at that time, those for CH4 were unchanged.

    As with the Hansen 1988 predictions, this inaccuracy in early line-by-line radiative codes led to some overestimation of climate sensitivity and warming in those earlier GCMs - which, mind you, was not specifically due to errors in the GCMs, as they were using the best values available at the time. 

  49. bcglrofindel - Keep in mind that the FAR results from 1990 are just that, 25yr. old results, that the state of the art and available data has only improved since then, and that current work gives more detailed results that earlier works are generally consistent with. 

    As with the early 'hockey-stick' work by Mann et al, nobody claims perfection in early work, nor even in current science. But the work since those seminal papers and early reports has only confirmed the general conclusions regarding AGW, and small decades old issues visible only from the perspective of current science don't invalidate the entire field

    In short, we're still seeing warming, it's consistent with about 3C/CO2 doubling +/-, the models are reasonably accurate for longer term trends (just not short term unpredictable variability that they've never been claimed to deal with), and there's really neither evidence nor reason to think that those basic facts will change. No matter how much 'skeptics' re-examine old papers and reports with ever smaller nit-picking. 

  50. "Yes, there are plenty of caveats to be included, but simple is better."

    Is it? Present that graph without the cavaets to "Joe Blow public", and (especially if he is a republican apparently) he will jump to conclusion that models can't be trusted that climate sensitivity is overestimated. These would be invalid conclusions. You dont jump to the same conclusion for the graph KR showed which compares FAR with actual forcings.

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