The impact of the “hiatus”?

Tamino has an interesting post about the recent slowdown in surface warming. His post essentially points out that if you consider a long enough time interval, it’s pretty hard to find evidence for a slowdown. I do think we have had slower surface warming in the last decade or so than in the previous decades, but I think he is right that in 10 or 20 years time it will not be particularly evident that we went through a period of slower surface warming in the early 21st century.

credit : England et al. (2015)

credit : England et al. (2015)

On that note, I thought I might briefly mention a recent paper by England, Kajtar & Maher called Robust warming projections despite the recent hiatus. Essentially it selected only those climate models that had a 14-year period during the interval 1995-2015, with a surface temperature trend of 0.09oC per decade, or less. This gives 19 (out of 90) RCP8.5 models, and 19 (out of 108) for RCP4.5.

The result is shown by the figure on the right and illustrates that the impact of the “hiatus” on projections by 2100 is relatively small; almost negligible. This makes reasonable sense. If the hiatus is partly due to interval variability, then we would expect accelerated warming quite soon and we would expect periods of faster than average warming to largely compensate for periods of slower than average warming. Of course, there are other explanations for the “hiatus”, including more volcanic activity than included in the models, and smaller forcing changes than was expected. None of these would, however, change the projections either.

Anyway, thats all I was going to say. It is likely that the “hiatus” is broadly irrelevant both for the reasons indicated in Tamino’s post and because even if there has been a recent slowdown in surface warming, it probably won’t have a noticeable effect on the long-term projections.

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39 Responses to The impact of the “hiatus”?

  1. Robert Way says:

    To me the idea that there wouldn’t be short-term periods with slower surface warming was always ludicrous. If you take all the relevant considerations into account (including one or two people don’t think so much about 😉 more on that later) there isn’t really much in terms of an inconsistency with climate models so I still don’t understand why the issue has gotten so much attention. It is only by assuming that we will always follow the multi-model mean that people come to erroneous conclusions.

  2. JCH says:

    Well, there is this vanishingly itty bitty possibility that there is a stadium wave.

  3. Robert,

    To me the idea that there wouldn’t be short-term periods with slower surface warming was always ludicrous.

    I agree, and that many who seem to make a big deal of it also claim natural variability plays a role makes it even more ludicrous.

    JCH,
    An itty bitty possibility 🙂

  4. anoilman says:

    What hiatus? What all this then? When that that happen?
    http://iopscience.iop.org/1748-9326/6/4/044022

  5. Well, there is this vanishingly itty bitty possibility that there is a magical force X.

  6. BBD says:

    Well, anyone who reads my comments knows that this study must be 100% correct

    /confirmation bias

    But seriously folks, this is why I have suggested that the slowdown in the rate of surface warming cannot be used to argue for low sensitivity – either TCR as formally defined – or ECS.

  7. V. V> says: “Well, there is this vanishingly itty bitty possibility that there is a magical force X.

    Yes, and now my keyboard and monitor need to be cleaned from the coffee that just splurted out all over them. Thanks.

    More seriously, isn’t it obvious from measurements of the Earth’s incoming and outgoing radiation that the planet has to be warming? The fixation on surface temperatures may be rational in that we live on the surface, but confusing the surface with the planet as a whole (or satellite TLT measurements) seems a delusion that is suffered disproportionately by pseudosceptics.

  8. christian says:

    Robert,

    “It is only by assuming that we will always follow the multi-model mean that people come to erroneous conclusions.”

    This is because most people think that the mean of model in predictions will be the better fit for global temperature, this is true if internal variability is mostly random, but in times where (eg. PDO ) it goes under regime shift, the signal is no more random and the mean is no more a good fit, because the mean of models cuts the internal varibility from the Members in Models to zero and then people come to erroneous conclusions.

  9. Given the steady rise in CO2 as a result of humans burning fossil fuels, and the proven reality of the greenhouse effect, surely heat has to be building up on the planet? The only questions are the relative uptake by land, ocean and atmosphere, and noise caused by relatively small short-term natural variations in the carbon cycle (sun’s output, volcanic activity and the like: all relatively easily observed).

    It’s bloody obvious global surface temperature will continue its rising trend, even to someone like me whose formal science education stopped at age 16. I mean it’s not complicated, is it? The only complication occurs when you try to predict the rise from year to year.

  10. BBD says:

    johnrussell

    Yes, but you know how it goes: the pause-that-isn’t is ‘proof’ in the eyes of some that sensitivity has been wildly over-estimated by those alarmists at the IPCC…

  11. JCH says:

    Farce X is, of course, natural?

  12. John Hartz says:

    England also posted an article, The climate ‘hiatus’ doesn’t take the heat off global warming on The Conversation. He does not pull any punches in it. His Conversation article was also reposted on SkS.

  13. angech2014 says:

    “Tamino has an interesting post about the recent slowdown in surface warming. His post essentially points out that if you consider a long enough time interval, it’s pretty hard to find evidence for a slowdown.”
    Tamino, to mention just one, is very keen on pointing out when people use cherry picking as an argument.
    A less used technique is broadening the baseline to exclude all data.
    His statement is essentially correct but becomes of limited use in any debate.
    Consider the “Coastline paradox”.
    The scale you use can be used to define or wipe out effects.

    BBD says:
    I have suggested that the slowdown in the rate of surface warming cannot be used to argue for low sensitivity – either TCR as formally defined – or ECS.

    *over the current time frame you are correct
    Over a much extended time frame? less so

  14. izen says:

    As Eli pointed out some time ago, there is plenty of trend at the bottom.

    The hiatus is largely an optical illusion caused by the way the human vision system processes upper contours. We look for the ‘top’ of things, so 98 is especially misleading.
    If you flip the graph of the last few decades, (rescale by -1 ) so that it becomes a graph of how much ‘COLD’ we are losing, then any hiatus in the rate cold years are reducing becomes much less evident.

    http://woodfortrees.org/plot/wti/compress:12/scale:-1/plot/wti/compress:1/scale:-1/trend

  15. “Tamino has an interesting post about the recent slowdown in surface warming. His post essentially points out that if you consider a long enough time interval, it’s pretty hard to find evidence for a slowdown.”

    Well, Tamino should know why there’s a slowdown because he was the one who identified why warming trends are less than Hansen C – because Forcing trends are less than Hansen C.

    The rate of forcing peaked some 25 years ago, of course there’s a slowdown.

    Since there are reasons to believe forcing rates will slow further, it would appear logical to predict that warming rates will slow also.

  16. JCH says:

    The PDO has progressively worked against warming since 1985: less and less assistance. Despite this progressive lack of assistance, it warmed aggressively. In 2006 the PDO finally had its brief little foray into its cold phase, which is likely done. Since then it has been warming aggressively. Because now the PDO is assisting, and could do this for several more years.

  17. anoilman says:

    Turbulent Eddie: Are you for real?

    You think climate scientists predict volcanoes? Are you that deluded? Geologists are all out of job with your way of thinking. Or perhaps you’re wrong!

    Do you think climate scientists predict all future solar variances? NASA out of job? Or perhaps you are wrong!

    And the ENSO warning system? You think those guys are out of a job because you (and only you Lucifer) think climate scientists predict all future ENSO events?

    Seriously. Are you really that deluded? Who told you that the IPCC predicts volcanoes? Who? I want names! I want papers!

  18. Of course only Turbulent Eddiie thinks this is about keeping score. The real scientific question is how well we can predict ENSO behavior.

    When we figure this out precisely, how will that make you feel? Will you pout? Same goes for AngieBaby2014, another one of those Aussie pouters from CE.

  19. JCH says:

    25 years ago atmospheric CO2 forcing was not higher than 1.88; it was lower. Just guessing, 1.2. So I think he’s talking about the yearly growth rate, which has been adding to CO2 forcing each year for the last 25 years.

    http://www.columbia.edu/~mhs119/GHGs/dF_GHGs.pdf

  20. izen says:

    @-angech2014
    “A less used technique is broadening the baseline to exclude all data.”

    Err, I think you need to rephrase this to avoid confusion, at the moment it is probably not even wrong.

    @-“His statement is essentially correct but becomes of limited use in any debate.
    Consider the “Coastline paradox”.
    The scale you use can be used to define or wipe out effects.”

    Yes, scale matters. The ship looking for a harbour and a shrimp in a rock pool have very different views of the coastline.
    Similarly the Mayfly with a 3 day lifespan has little concern for the climate beyond next week. Humans might have a biblical interest in 3 score years and 10. Societies might have a longer outlook. Although governments rarely seem to do better that 5 year plans or the next election.

    We ‘cherry-pick’ the time-scale that is most useful. Longer views of how the climate behaves can give us more information than shorter views. Just as a ships chart can give more information on where to find rock pools than any detailed map of a rock-pool.

  21. Thank-you, ATTP, for this post. What you wrote here is particularly welcome and relevant to what I present further below:

    “If the hiatus is partly due to interval variability, then we would expect accelerated warming quite soon and we would expect periods of faster than average warming to largely compensate for periods of slower than average warming.”

    I believe that the more scientists really push this type of point to the general public, the more the general public will be able to more fully appreciate the severity of the problem.

    Since this is about Tamino’s excellent post, I thought it might be appropriate to share here what I think are some interesting comments and/or graphs given by some commenters there at Open Mind, two under that post by Tamino and one under a recent post by Tamino where the commenter’s graph was I think relevant to this discussion, followed by what I think is a relevant article by robertscribbler about a couple of recent papers: The three graphs below suggest that the global surface temperature is on average following the path of an accelerating function underneath a multidecadal cycling since the late 1800s, which, when combined with the two papers robertscribbler writes about (and the two papers I mention further below), suggests the real possibility of an explosive increase over the middle parts of the 21st century during the next “up” of such cycling followed by essentially no slowdown at all during the following “down”, meaning no more slowdowns of any note ever again as long as humans keep spewing GHGs at high enough rates.

    (Side note: I think that such graphs that show an underlying accelerating function are representations that the general public would relate to much better than graphs that use nothing but straight lines showing an underlying increase – they simply don’t know what all these underlying straight lines actually mean, since most of them never took a statistics course, especially one at a sufficiently high level. But almost all did take a high school algebra course that covered some functions producing increasing curves. I believe that pushing such representations that show increasing curves rather than straight lines would help the general public see and appreciate the severity of the situation.)

    The commenter Olof wrote on April 30, 2015 at 3:50 pm:

    “If you want to remove annual variation, use a 12-month running mean. If you want to remove 60-year natural cycles, use a 60-year running mean. Until the day this curve starts to curve in the other direction, I would not speak of a “hiatus”…”

    [and then this commenter gives this graph:]

    Source: http://www.woodfortrees.org/plot/gistemp/mean:720

    The commenter marmocet wrote on April 30, 2015 at 11:27 pm:

    “… I combined the HadCRUT4, NOAA/NCDC and GISS LOTI data sets, ran a regression on them, then checked to see how many statistically significant powers of the fitted values I could add as explanatory variables to the regression equation. I’m sure this is some form of statistical malpractice, but I thought the chart the procedure produced was interesting:”

    [and then this commenter gives this graph:]

    Also at Open Mind, in the comment thread under the post “Stupid is as Ted Cruz does”, the commenter Gerg in the comment on April 2, 2015 at 10:53 am wrote:

    “At some point we’re going to have to start noticing that the problem is highly non-linear. That’s both in the observations and in the physics-based modelling, regardless of the odd bump and wiggle:”

    [He then links to a page with a nice graph, the graph I link on further below. I liked what he had to say at the related blog post, since it summarizes pretty nicely one’s frustration with all the nonsense in all the denial, and since I like to see attempts to try to keep things as general as possible, a focus on the big picture, the very long term, to try to see what’s in store for humanity and world ecology over the next couple of hundred years:]

    “More thoughts on global temperature”
    http://gergs.net/2014/12/thoughts-global-temperature/

    Quote: “Having taken the trouble to plot all eight popular global temperature series together on one graph at monthly resolution – something the other seven billion of you don’t seem to have bothered with – it may be fair to spare us the indulgence of a few simple observations…..Millions of bullshitter-hours of trouble making and thousands of scientist-hours of patient rebuttal – this urbanisation correction, that homogenisation, this clever interpolation, that gap filling; ignore those drifty satellites … not even surface temperatures; no, use the pattern but not the number – all to naught. For the purpose of grasping what we face it doesn’t matter. They’re all the same…..Global warming is a slow motion train wreck. What happens this year or even this decade isn’t really interesting. What terrifies is the long trend, particularly its acceleration….IPCC modelling just happens to fit simplistic extrapolations of common accelerating functions pretty much spot on, depending on your choice of greenhouse gas concentration pathway.”

    [He gives this graph below:]

    It seems abundantly clear that when cycles of up to roughly 60 years are allowed for, recent studies such as those by Marotzke and Forster (2015) with their 62 year runs and Steinman, Mann, and Wilson (2015) with especially their most general, multi-decadal NMO (see
    http://www.realclimate.org/index.php/archives/2015/02/climate-oscillations-and-the-global-warming-faux-pause/
    for more on this NMO) show that the models are holding up just fine with respect to the very long term to see what’s in store for humanity and world ecology. (On this NMO: I think that its complete generality – seemingly quite a bit more general than either the PDO or the AMO, since it’s about the entire Northern Hemisphere – is most appealing since it may be general enough to be a measure for any proposed mechanism of types suggested by such as Chen and Tung (2014).)

    But the GHG effect could become so strong that by the end of this possibly steepest-yet extra acceleration throughout the middle of the 21st century there might not be any meaningful slowdown ever again as long as humans keep the GHG spewing at high enough rates:

    https://robertscribbler.wordpress.com/2014/09/03/no-more-hiatus-human-emission-to-completely-overwhelm-nature-by-2030/

    Quote: “Keep burning fossil fuels at current rates and you can kiss nature’s influence over temperature good-bye. That’s the conclusion of two recent scientific studies.”

  22. JCH says:

    (Side note: I think that such graphs that show an underlying accelerating function are representations that the general public would relate to much better than graphs that use nothing but straight lines showing an underlying increase – they simply don’t know what all these underlying straight lines actually mean, since most of them never took a statistics course, especially one at a sufficiently high level. But almost all did take a high school algebra course that covered some functions producing increasing curves. I believe that pushing such representations that show increasing curves rather than straight lines would help the general public see and appreciate the severity of the situation.) …

    Well, first of all, you have all this observation-based CS rot.

  23. Excellent comment, @KeefeAndAmanda.

    The big picture view is all I’m really interested in and why I am so concerned. I know we’re not allowed to say “the science is settled” any more, but the truth is that the science should no longer be a concern to anyone but scientists. Nit-picking the science by the army of great unqualified is just a massive time-waster. What matters is “just what the fuck are we going to do about this train wreck of a problem”?

  24. BBD says:

    angech

    *over the current time frame you are correct
    Over a much extended time frame? less so

    What are you taking about? The recent slowdown in the rate of surface warming exists only over a short period of time. Over longer periods, the high level of uncertainty over aerosol negative forcing, ocean heat content and even GAT make the so-called ‘observational’ estimates of S moot, at best. Not to mention the fact that they do not incorporate non-linear feedbacks.

    Have a look at Keefandamanda’s comment above.

  25. angech2014 says:

    BBD says:
    *over the current time frame you are correct Over a much extended time frame? less so”
    “What are you taking about? The recent slowdown in the rate of surface warming exists only over a short period of time.”
    If one uses a scale for estimated surface temperature over a thousand years compared to one over 5000 or 50,000 years, short term trends in a 164 year record become increasingly invisible even when large.
    This applies to both seeming pauses and slightly longer seeming rises.
    Both you [“the recent slowdown in the rate of surface warming”} and ATTP [ “I do think we have had slower surface warming in the last decade or so than in the previous decades”] recognize the semblance of a slowdown, precursor to a pause.
    Tamino has never given it any credence, refusing to acknowledge it
    “if you consider a long enough time interval, it’s pretty hard to find evidence for a slowdown.”
    but as I point out, his argument rests on time frames.

  26. angech2014 says:

    KeefeAndAmanda says:
    Thank-you, ATTP, for this post. What you wrote here is particularly welcome and relevant to what I present further below: “If the hiatus is partly due to interval variability, then we would expect accelerated warming quite soon and we would expect periods of faster than average warming to largely compensate for periods of slower than average warming.”

    Asking for some patience here.
    GHG effects are more or less instantaneous in the atmosphere.*
    I base this on two indisputable facts.
    1. It is recognized that any atmosphere with GHG in will exhibit warming and cooling at a rate commensurate to the amount of GHG present as it is warmed and cooled by the passage of the sun*
    2. The temperature change of the surface atmosphere between day and night will often vary at least 20 degrees*. Hence a large change in the amount of heat in the atmosphere happens over a very short time frame dependent proportionally on the amount of GHG.

    Hence, ATTP, my argument is that the heat from CO2 levels which are reputedly fairly consistent must be present at the right level for such an amount of GHG every day.

    Your argument as well I expect.

    Natural variability must therefore exist and the problem is that natural variability is a term for we do not know what the other causes are that are stopping the temperature from going up as predicted.

    Obviously I would and have argued that Climate Sensitivity is less than predicted for the usual suspects of negative feedbacks from clouds, aerosols and other causes of increased albedo.
    I suspect that BBD and yourself acknowledge that this may have a small effect.

    But this is at odds with the overall concerns that you have and other ideas which are more debatable are put up which have traction.

    There is a lot of emphasis put into high Climate Sensitivity and lots of runaway graphs which do not equate with what the historic record of the earth’s atmosphere shows. At the moment this idea is not working.

  27. mwgrant says:

    Willard,

    In winning he must suffer even more. At least I now know my label…collateral damage.

  28. verytallguy says:

    angech

    …lots of runaway graphs…

    A citation to at least some of these “lots” would help your argument here

  29. angech,
    I’m not sure I understand what you’re getting at. Maybe you clarify?

  30. angech2014 says:

    verytallguy says: May 5, 2015 at 7:28 am angech “…lots of runaway graphs…” citation.

    ATTP has a graph at the top with a lot of IPCC projections , most at accelerating rates.
    KeefeAndAmanda has provided a number of examples saying

    “The three graphs below suggest that the global surface temperature is on average following the path of an accelerating function underneath a multidecadal cycling since the late 1800s,”
    suggesting ” the real possibility of an explosive increase over the middle parts of the 21st century during the next “up” of such cycling followed by essentially no slowdown at all during the following “down”, meaning no more slowdowns of any note ever again as long as humans keep spewing GHGs at high enough rates.”

    “But the GHG effect could become so strong that by the end of this possibly steepest-yet extra acceleration throughout the middle of the 21st century there might not be any meaningful slowdown ever again”

    We do not live on a graph page with exponentially increasing functions. To state that ” there might not be any meaningful slowdown ever again” is a contradiction of science.
    Mathematically aside an exponential function must come to an end at a defined period as it approaches its y axis limit.
    To have an exponential increase one must have an exponential input and humans are not capable of maintaining this.
    Put up a graph of C02 increase, Put up a parallel line of expected temperature increase.
    Add positive and negative feedbacks when they are proven not surmised.
    Ignore 10-30 year jumps or drops as suggesting strong trends.
    Accept that at the moment the temperature rise has not kept pace with the CO2 increase and ask for more research into why this is so.
    Very happy for people to work to alter environmental change, needed.
    Climate change needs to have good, explainable maths not scare tactics.

  31. JCH says:

    We have not had a real cooling since 1940. That was before Pearl Harbor.

  32. angech,

    Accept that at the moment the temperature rise has not kept pace with the CO2 increase and ask for more research into why this is so.

    Except there has been so much research on this that some blogs are mocking how many different ideas there are. Also, the OHC has not slowed, which is the fundemental indicator of AGW.

  33. verytallguy says:

    Angech,

    you claimed “runaway”

    None of your examples show a “runaway”.

    Eg your “no more slowdowns of any note ever again as long as humans keep spewing GHGs at high enough rates.”

    All this is saying is that temperatures will rise as CO2 rises.

    If you extend ATTPs graph another century, the rate of increase will slow.

    You’re tilting at windmills.

  34. BBD says:

    angech

    If one uses a scale for estimated surface temperature over a thousand years compared to one over 5000 or 50,000 years, short term trends in a 164 year record become increasingly invisible even when large.
    This applies to both seeming pauses and slightly longer seeming rises.
    Both you [“the recent slowdown in the rate of surface warming”} and ATTP [ “I do think we have had slower surface warming in the last decade or so than in the previous decades”] recognize the semblance of a slowdown, precursor to a pause.

    Obfuscation. Climate changes for a reason. Whatever time-scale you use (within the Holocene), you will need to consider the kind of forcing change that would have resulted in a warming similar to the modern. Climate does not change like this because of magic or whim and your argument is at that level.

    This is a 10ky illustration of major forcing change. This is why there has been ~0.8C warming over the last ~150y. This is the physical reality you are denying:

    http://www.ipcc.ch/publications_and_data/ar4/syr/en/figure-2-3.html

  35. BBD says:

    OT, but good news is in such short supply: Profits halve at News Corp.

  36. angech2014 says:

    “The OHC has not slowed, which is the fundamental indicator of AGW.”
    The ocean heat content is a slippery, nebulous beast. Not one which I would prefer to use as “the fundamental indicator”.
    The main objections being the slow time frame and difficulty in measuring change in 0.1 of a degree over decades and the slow response time to changes in CO2.
    We point to various indicators of global warming.
    Surface temperature suffers from the same problem [a slippery, nebulous beast], has more natural variation and a much faster reaction time.
    It is directly affected by GHG factors like CO2 increase and water vapor and has a very quick response time.
    Given the laws of physics one should be able to say CO2 level x, temperature y.
    If we understood clouds , currents, volcanoes, coastlines and seasons better we “could” take the natural variation out and should have 2 related trends.
    But we do not.
    In which case either we need to improve our science or consider the vague possibility of lower Climate sensitivity or negative feedbacks.
    Point blank dismissal of either concept is poor science, I hope we all except that.
    Romantic reasoning of “the natural variability did it” just emphasizes my point that the science is not good enough yet to be making dogmatic statements.
    The main problem is that no one on either side is prepared to concede one inch on their viewpoints. I understand that if one does the other side makes hay.

  37. lerpo says:

    Hi angech2014,

    You mention: “Given the laws of physics one should be able to say CO2 level x, temperature y.
    If we understood clouds , currents, volcanoes, coastlines and seasons better we “could” take the natural variation out and should have 2 related trends. But we do not.”

    Tamino does exactly this: https://tamino.wordpress.com/2011/12/06/the-real-global-warming-signal/

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