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Climate Oscillations and the Global Warming Faux Pause

Filed under: — mike @ 26 February 2015

No, climate change is not experiencing a hiatus. No, there is not currently a “pause” in global warming.

Despite widespread such claims in contrarian circles, human-caused warming of the globe proceeds unabated. Indeed, the most recent year (2014) was likely the warmest year on record.

It is true that Earth’s surface warmed a bit less than models predicted it to over the past decade-and-a-half or so. This doesn’t mean that the models are flawed. Instead, it points to a discrepancy that likely arose from a combination of three main factors (see the discussion my piece last year in Scientific American). These factors include the likely underestimation of the actual warming that has occurred, due to gaps in the observational data. Secondly, scientists have failed to include in model simulations some natural factors (low-level but persistent volcanic eruptions and a small dip in solar output) that had a slight cooling influence on Earth’s climate. Finally, there is the possibility that internal, natural oscillations in temperature may have masked some surface warming in recent decades, much as an outbreak of Arctic air can mask the seasonal warming of spring during a late season cold snap. One could call it a global warming “speed bump”. In fact, I have.

Some have argued that these oscillations contributed substantially to the warming of the globe in recent decades. In an article my colleagues Byron Steinman, Sonya Miller and I have in the latest issue of Science magazine, we show that internal climate variability instead partially offset global warming.

We focused on the Northern Hemisphere and the role played by two climate oscillations known as the Atlantic Multidecadal Oscillation or “AMO” (a term I coined back in 2000, as recounted in my book The Hockey Stick and the Climate Wars) and the so-called Pacific Decadal Oscillation or “PDO” (we a use a slightly different term–Pacific Multidecadal Oscillation or “PMO” to refer to the longer-term features of this apparent oscillation). The oscillation in Northern Hemisphere average temperatures (which we term the Northern Hemisphere Multidecadal Oscillation or “NMO”) is found to result from a combination of the AMO and PMO.

In numerous previous studies, these oscillations have been linked to everything from global warming, to drought in the Sahel region of Africa, to increased Atlantic hurricane activity. In our article, we show that the methods used in most if not all of these previous studies have been flawed. They fail to give the correct answer when applied to a situation (a climate model simulation) where the true answer is known.

We propose and test an alternative method for identifying these oscillations, which makes use of the climate simulations used in the most recent IPCC report (the so-called “CMIP5” simulations). These simulations are used to estimate the component of temperature changes due to increasing greenhouse gas concentrations and other human impacts plus the effects of volcanic eruptions and observed changes in solar output. When all those influences are removed, the only thing remaining should be internal oscillations. We show that our method gives the correct answer when tested with climate model simulations.

2015-02-12-Sci15FigHuffPost.png
Estimated history of the “AMO” (blue), the “PMO (green) and the “NMO” (black). Uncertainties are indicated by shading. Note how the AMO (blue) has reached a shallow peak recently, while the PMO is plummeting quite dramatically. The latter accounts for the precipitous recent drop in the NMO.

Applying our method to the actual climate observations (see figure above) we find that the NMO is currently trending downward. In other words, the internal oscillatory component is currently offsetting some of the Northern Hemisphere warming that we would otherwise be experiencing. This finding expands upon our previous work coming to a similar conclusion, but in the current study we better pinpoint the source of the downturn. The much-vaunted AMO appears to have made relatively little contribution to large-scale temperature changes over the past couple decades. Its amplitude has been small, and it is currently relatively flat, approaching the crest of a very shallow upward peak. That contrasts with the PMO, which is trending sharply downward. It is that decline in the PMO (which is tied to the predominance of cold La Niña-like conditions in the tropical Pacific over the past decade) that appears responsible for the declining NMO, i.e. the slowdown in warming or “faux pause” as some have termed it.

Our conclusion that natural cooling in the Pacific is a principal contributor to the recent slowdown in large-scale warming is consistent with some other recent studies, including a study I commented on previously showing that stronger-than-normal winds in the tropical Pacific during the past decade have lead to increased upwelling of cold deep water in the eastern equatorial Pacific. Other work by Kevin Trenberth and John Fasullo of the National Center for Atmospheric Research (NCAR) shows that the there has been increased sub-surface heat burial in the Pacific ocean over this time frame, while yet another study by James Risbey and colleagues demonstrates that model simulations that most closely follow the observed sequence of El Niño and La Niña events over the past decade tend to reproduce the warming slowdown.

It is possible that the downturn in the PMO itself reflects a “dynamical response” of the climate to global warming. Indeed, I have suggested this possibility before. But the state-of-the-art climate model simulations analyzed in our current study suggest that this phenomenon is a manifestation of purely random, internal oscillations in the climate system.

This finding has potential ramifications for the climate changes we will see in the decades ahead. As we note in the last line of our article,

Given the pattern of past historical variation, this trend will likely reverse with internal variability, instead adding to anthropogenic warming in the coming decades.

That is perhaps the most worrying implication of our study, for it implies that the “false pause” may simply have been a cause for false complacency, when it comes to averting dangerous climate change.

158 Responses to “Climate Oscillations and the Global Warming Faux Pause”

  1. 101
    prokaryotes says:

    I thought this was common knowledge now, that “there isn’t a hiatus of AGW”, instead a variation of the energy distribution, thus ocean taken up the heat.

    To repeat. When will the ocean heat come back to haunt us?

  2. 102
  3. 103
    Steve Fish says:

    Re- Comment by prokaryotes — 4 Mar 2015 @ 10:33 AM, ~#99

    If the heat is in the ocean the earth has warmed and the haunting continues. As the ocean gradually warms its volume increases, weather changes, the rate of ice melt increases, and the rate of heat and CO2 uptake by the ocean reduces. Maybe I don’t understand your question.

    Steve

  4. 104
    calyptorhynchus says:

    “the dominant hippie culture” there should be a few testable predictions to make with this:
    1. Widespread legalisation of all drugs
    2. Soap/shampoo manufacturers going out of business
    3. Kaftan manufacturers doing a roaring trade

  5. 105
    Hank Roberts says:

    Nafeez Ahmed* — here quoting Gavin among others on the warming trend.

    How’d he do on this one?
    ____________________
    *search his name for priors

  6. 106
    prokaryotes says:

    Steve, if the heat is in the ocean, the atmosphere has not warmed. My question in #100 is repeating Rob Painting’s excellent article from 2013 “A Looming Climate Shift: Will Ocean Heat Come Back to Haunt us?”.

    The key points were

    Despite a large increase in heat being absorbed by the Earth’s climate system(oceans, land & ice), the first decade of the 21st century saw a slowdown in the rate of global surface warming (surface air temperatures).

    A climate model-based study, Meehl (2011), predicted that this was largely due to anomalous heat removed from the surface ocean and instead transported down into the deep ocean. This anomalous deep ocean warming was later confirmed by observations.

    This deep ocean warming in the model occurred during negative phases of the Interdecadal Pacific Oscillation (IPO), an index of the mean state of the north and south Pacific Ocean, and was most likely in response to intensification of the wind-driven ocean circulation.

    Meehl (2013) is an update to their previous work, and the authors show that accelerated warming decades are associated with the positive phase of the IPO. This is a result of a weaker wind-driven ocean circulation, when a large decrease in heat transported to the deep ocean allows the surface ocean to warm quickly, and this in turn raises global surface temperatures.

    This modelling work, combined with current understanding of the wind-driven ocean circulation, implies that global surface temperaures will rise quickly when the IPO switches from the current negative phase to a positive phase.Source

    The quoted theory is similar to Mike’s, but today more fine grained, includes the entire system. We will find out about it, once the index changes, once ENSO changes significantly (Probably during next El Nino).

    Similar back in 2001: The IPO modulates teleconnections with ENSO in a complex way, strengthening relationships in some areas and weakening them in others. For New Zealand, there is a consistent bias towards stronger teleconnections for the positive IPO period. These results demonstrate that the IPO is a significant source of climate variation on decadal time scales throughout the South West Pacific region, on a background which includes global mean surface temperature increases.Source

  7. 107
    wili says:

    Here’s a story on a similar study as the main post: http://www.mprnews.org/story/2015/03/04/global-warming-study

    “Study: Shift in ocean temperatures temporarily slowed global warming”

    “A new study in the journal Science by a University of Minnesota Duluth professor argues that a recent slowdown in global warming is caused by decades-long variations in ocean temperatures.

    The rate of global warming has slowed by nearly half since the late 1990s. Temperatures are still rising, but not at the rate that climate change models have predicted.

    That in turn has fueled a debate between climate change scientists and those who deny a human link to global warming.

    The new research by Byron Steinman, an assistant professor of geological sciences at UMD’s Large Lakes Observatory, concludes that the slowdown in warming is caused by natural oscillations in ocean temperatures similar to the cycle of El Niño and La Niña, but takes place over several decades.

    ‘The slowdown is largely a result of a negative trend in the Pacific Ocean, Pacific sea surface temperatures,’ he said. ‘When this trend reverses, we’re very likely to see an accelerated rate of warming.'”

  8. 108
    Glen Koehler says:

    Dr. Manning
    Is it statistically justifiable to quantitatively project the AMO, PMO and NMO patterns forward to estimate coming influence of internal variability on rate of temperature rise?
    I did it visually (using your CMIP5-All curves) and it appears that the negative NMO ends and starts rising slowly around 2020. For 2020-2040, PMO and AMO are out of phase, with the PMO rise and AMO fall resulting in essentially neutral or slightly rising NMO, which would manifest as an acceleration in temperature increase trend compared to recent strongly negative NMO. Then for 2041-2060 both PMO and AMO are positive, resulting in a positive NMO about three times the slope of the 1975-1998 NMO. Which I interpret as “Yikes”. These estimates seem consistent with other projections (e.g. England et al. 2014, DOI: 10.1038/NCLIMATE2106; and Roberts et al. 2015, DOI: 10.1038/NCLIMATE2531), and with the idea that large increase in ocean heat storage is getting overdue to return via a strong El Nino sooner than later.
    Not my field (which you’ve probably already figured out) but as a passenger on this planet with children I’d like a heads up on what’s coming.
    Thanks to you and others for providing this forum, for the work that you do, and for standing up for reality.
    Finally, for moral support, there’s a great 4 minute Feb. 26 Senate floor speech rebutting Jim Snowball Inhofe by Sheldon White (D-RI) at https://www.youtube.com/watch?v=oTdpdFUTyqs
    – Glen

  9. 109
    Glen Koehler says:

    Dr. Manning
    Is it statistically valid to quantitatively project the AMO and PMO curves forward to estimate near future NMO?
    I did that visually using the CMIP-All versions and weightings of AMO and PMO. That suggests that negative NMO ends around 2020, with rising PMO and falling AMO yielding near neutral or slightly rising NMO for 2021-2040, which would manifest as an upswing in the temperature curve relative to 1998-2014 strongly negative NMO.
    Then for 2041-2060 both PMO and AMO trend positive, yielding a strongly positive NMO about 3X the slope of NMO during the 1976-1998 temperature rise, i.e. “Yikes!”.
    While informal, these outcomes are consistent with your closing statement and with other recent outlooks for the coming end of the hiatus (e.g. England et al. 2014, DOI: 10.1038/NCLIMATE2106; & Roberts et al. 2015, DOI: 10.1038/NCLIMATE2531 ). They also fit with idea that tremendous increase in ocean heat storage since 1998 is getting overdue to express itself in a strong El Nino or two. I’m wondering if these estimates seem valid to those with expertise in the field (which does not include me).
    Thanks for providing this forum, for the work you do, and for standing up for reality against those who aggressively prefer their comfortable delusion.
    There’s a great Feb. 26 Senate floor speech video (4 minutes) of Sheldon Whitehouse (D-RI) rebutting James Inhofe’s snowball charade at https://www.youtube.com/watch?v=oTdpdFUTyqs
    – Glen

  10. 110
  11. 111
    Hank Roberts says:

    Can someone offer or point to a simple (“fifth-grader”) clarification of the various three letter acronyms? Wikipedia asks for help:

    Pacific decadal oscillation
    From Wikipedia, the free encyclopedia
    This article needs attention from an expert in Climate change …

    Recent papers use various of these TLAs — IPO, PDO, AMO.

    Here we have — my ellipses, trying to clarify:

    “AMO” (… coined back in 2000) and … “PDO” (we a use … “PMO” to refer to the longer-term features of this [PDO] apparent oscillation)…. “NMO” … a combination of the AMO and PMO.

    Has anyone done a grid/matrix for all these to clarify what data sets, corresponding (we hope) to features of the real world, each TLA is meant to refer to?

  12. 112
  13. 113
    Jim Baird says:

    Dr. Mann, the Guardian quotes you as follows, “If anything, we’ve been lulled into a false complacency by the fact that internal oscillations in the climate system temporarily masked some of that warming. That may come back to bite us as these oscillations swings back in the other direction and add to global warming in the decades ahead.”

    As noted at “70”, instead of this heat coming back to bite us, we can mechanically drive it into the ocean and produce the zero emissions needed to address climate change. This process addresses as well the two greatest risks of “warming”; sea level rise and storm surge.

    The greatest threat from SLR is icecap melting. Driving tropical heat into the depths with heat pipes short-circuits the movement of this heat towards the poles where it melts the icecaps and saps the energy of tropical storms. The coefficient of thermal expansion of sea water at a depth of 1000 meters is also half that of the tropical surface.

    It seems to me the real false sense of complacency is thinking that studying the problem without acting on what you have learned is of scientific, let alone societal, benefit.

    If this is illogical, I would welcome being set straight.

  14. 114
    Glen Koehler says:

    ooops, Dr. MANN (talk about faux pas!)

  15. 115
    Hank Roberts says:

    > zero emissions needed to address climate change

    Mixing more air into the ocean faster isn’t “zero emissions” — it’s a way of rushing ocean pH change faster than it’s happening already.

    Better alternatives have been suggested, e.g.

    Emergency 20-year drawdown of excess CO2 via push-pull ocean pumps (at Climate CoLab a few years ago)

  16. 116
    Pete Dunkelberg says:

    Wili @ 109: El Niño? I’m not sure. Check the BOM:
    http://www.bom.gov.au/climate/enso/#tabs=Overview

  17. 117
    martin ross says:

    I would suggest that aerosols from rocket emissions above the tropopause also are cooling the surface a little, something like the mysterious (and let’s be honest a little ad hoc) “Goldilocks volcanoes”…..not so big to be seen but not so small to not affect lower strat energy flows. The soot and alumina aerosols from rockets are real and can have dramatic effects. We do not know enough about rocket soot and alumina optical properties to be very definitive (and rocket exhaust has been pretty much ignored by the GCM community) but the numbers suggest to me that rocket exhaust is preferred over Goldilocks volcanoes. Something to consider.

  18. 118
    patrick says:

    #68 Susan Anderson

    Thank’s for the link to Ray Pierrehumbert’s analysis on hacking the climate. It epitomizes sanity.

    http://www.slate.com/articles/health_and_science/science/2015/02/nrc_geoengineering_report_climate_hacking_is_dangerous_and_barking_mad.html

  19. 119
  20. 120

    #118–Yes. For example:

    But if it comes to albedo hacking, the result won’t be pretty. It won’t be some benign “Plan B,” but more like the constant fear of thermonuclear holocaust I grew up with during the Cold War. It will be the end of blue skies and crystal-clear starry nights, and the beginning of nightly blood-red sunsets. These are not the most serious consequences of albedo hacking, but they will serve as nightly visible proof of our moral failure.

  21. 121
    HR says:

    Small point.
    Many papers seem to point to Kerr et al (2000) as the reference for Atlantic Multidecadal Oscillation” rather than anything by you. Could you clarify how it was you that coined it?

    [Response: Kerr et al (2000) is the first place the term appears in print. Kerr et al was a commentary about an article by Delworth & Mann (2000). Kerr, in his interview with me, asked me what we should call this new signal and I obliged. There is a more detailed discussion in my book The Hockey Stick and the Climate Wars. –Mike]

  22. 122
    wili says:

    Pete, thanks for the BOM link. They do tend to be a bit more conservative about declaring these thinks. Perhaps wisely, since El Nino patterns have been so tricky in the past few years.

    patrick, thanks for those links.

    To all and sundry (if sundry is still in the building ‘-) ): So if we add (1) a probable El Nino year and (2) a probable year when Arctic sea ice reaches a new low extent in September to (3) the shifts in ocean currents discussed in this article, doesn’t that all just further commit us to a greatly accelerated rate of global warming in the coming years and decades?

  23. 123
    Hank Roberts says:

    I do wish this crowd (well, some of you) were all present in some forum where amelioration was open to extended discussion.
    For example Bill Calvin’s 20-year emergency CO2 drawdown suggestion, admittedly a first draft idea but — why not? Pointer welcome to an appropriate discussion, wherever.

  24. 124

    #123–Maybe you could combine it with OTEC to make it a self-powered process?

    http://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion

  25. 125
    Steve Fish says:

    Re- Comment by wili — 6 Mar 2015 @ 11:45 AM, ~#122

    Hey Wili, please do me a favor. I responded to your post at ~#122 and it went to the Bore Hole (1589). I wasn’t disagreeing with the facts presented in the topical post on which we both agree. I was talking about how we all should talk about the science. I am concerned that we not make the same intellectual mistake as the deniers when talking about the significance of short term oscillations. Take a look at it and tell me what you think relative to the other crap that is posted.

    Thanks, Sundry (Steve)

  26. 126
    Muon says:

    R Gates,
    Just how robust though are the TOA and OHC data (relative to surface temps)? Careful – talking about “psuedoscience” might backfire badly.

  27. 127
    wili says:

    Steve Fish, thanks for pointing me to your response. But I don’t completely follow your reasoning. Even if there were absolutely no change in the slope of trend in atmospheric (or total) global warming, one could still talk about a possible new acceleration just around the corner. I have a feeling, though, that I am somehow missing your main point here.

  28. 128
    Steve Fish says:

    Re- Comment by wili — 7 Mar 2015 @ 9:00 AM, ~#127

    Thanks for responding Wili. I am going to pursue this a little further because I think that it is important to be thoughtful about what we say here. RC is an education site and I think we should try to not make misleading comments. Here is one recent example: Prokaryotes, now at #101, recognizes that the “ocean [has] taken up the heat,” and then says- “When will the ocean heat come back to haunt us?” Somebody coming here to learn may respond to this with “oh dear, not only is it going to get warmer but the extra heat stored in the ocean is going to come bursting back out.” I know that Prokaryotes didn’t intend this meaning, but the context gives the appearance that he did.

    In your post, currently at #122, you provided a context that included oscillatory events, that are the specific topic of the original essay thread starter, which have been shown to not effect global warming but to oscillate surface and ocean heat gain about the ongoing total (global) temperature increase, but you then ask if this won’t “just further commit us to a greatly accelerated rate of global warming in the coming years and decades?” This might suggest to a naïve learner that the oscillations will in the future increase the rate of global temperature rise when in fact we know that only surface temperature will be affected. I know that you understand this but when communicating, context is important to meaning.

    You may believe that I am creating a small issue here but, if so, I disagree. As an educator at a fairly high level I learned how important it is to try to be precise in communicating science in order to promote understanding. Also, in the context of this forum, we are frequently confronted by science denier types who hype any small bump in the data in the direction they wish to promote (e.g. down the up staircase), and for our own intellectual honesty it is very important that we not appear to be playing their game in the opposite direction. Appearance can be more important than actual intent.

    Finally, the problem here might simply be that I just have to keep at learning how to communicate accurately because my original response to you was misunderstood and deleted, but I don’t see how it could be misconstrued to be that bad.

    Steve

  29. 129
    Mal Adapted says:

    calyptorhynchus:

    “the dominant hippie culture” there should be a few testable predictions to make with this:
    1. Widespread legalisation of all drugs
    2. Soap/shampoo manufacturers going out of business
    3. Kaftan manufacturers doing a roaring trade

    4. Everyone wearing headbands, love beads and bell-bottoms again
    5. Three-day anarchic rock festivals every summer
    6. Vinyl LPs replacing CDs and MP3s
    Since we’re not seeing any of that, the hypothesis that the dominant culture is hippie is falsified. Whew – glad to have said goodbye to all that 30 years ago 8^D!

  30. 130
    Hank Roberts says:

    > wili …. so if we add (1)…(2)…(3)
    (1) is natural variability, up and down
    (2) additional forcing you attribute to more open water in the Arctic?
    (3) is natural variability, up and down

    > wili …. a possible new acceleration just around the corner

    Please reread Gavin’s inline reply to JJ at
    http://www.realclimate.org/index.php/archives/2015/02/unforced-variations-feb-2015/comment-page-6/#comment-625830

    Telling scary stories and insisting climatologists should be modeling them and policymakers assuming just in case isn’t getting anyone anywhere. Reality has them plenty busy.

    You can find serious study done on each of the possibilities if you use Scholar’s search function. It doesn’t add up to a pocalypse. Nonetheless, reality is plenty scary.

  31. 131
    Bob says:

    Surface temperature data indicate that the warming trend continues. Lower atmosphere temperature data indicate that the warming trend has paused. It has always been my understanding that, due to the heat generated by the CO2-drven greenhouse effect, temperatures in the lower atmosphere should be rising at a rate faster than temperatures at the surface. They are not, and here I refer specifically to the last decade. So either 1) I cannot read graphs or 2) the surface temperature data are wrong or 3) the lower atmosphere temperature data are wrong or 4) the global warming hypothesis is wrong. Which is it?

  32. 132
    MARodger says:

    Bob @131.
    It would help a lot ig we knew what “lower atmospher temperature data” you’re looking at. If I put a regression line through, say, UAH LTL global data, I don’t see any “pause” which would suggest (1) – You can’t read graphs. But then, maybe you are looking at other data.

  33. 133
    Hank Roberts says:

    Bob, specify what data and graphs you’re looking at, and how you get a trend using that data set specific to the past decade, and someone might help.
    Are you reading Climate Etc. where something like this is a hot topic?

  34. 134
    Ray Ladbury says:

    Bob,
    I’m pretty sure your “lower atmosphere temperature” is not being measured by thermometer. If it is a satellite dataset, the raw measurements require considerable massaging before you can get anything resembling a temperature. And the satellite series are particularly prone to exaggerating the effect of ENSO, with La Nina years appearing particularly warm and El Nino years particularly cool.

    So, maybe you can read graphs, but you have no idea what you are reading.

    Example:

    Otto: “Apes don’t read philosophy.”
    Wanda: “Yes they do, Otto. They just don’t understand it.”

  35. 135
    JCH says:

    Steve Fish – the layers of the oceans that are both storing heat and are also moved around by ENSO events can come back to haunt us. I believe that is one reason why the global mean temperature has rebounded so strongly since 2012.

  36. 136
    Mal Adapted says:

    Me:

    glad to have said goodbye to all that 30 years ago

    My memory seems to have elided a decade: make that 40 years ago. Dang, time flies when you’re getting old 8^}!

  37. 137
    Thomas O'Reilly says:

    I agree with Steve when he says in “….”

    “it is important to be thoughtful about what we say here.”
    Plus what is said in climate science papers Abstracts and IPCC reports.

    “we should try to not make misleading comments.”

    “…. didn’t intend this meaning, but the context gives the appearance that he did.”
    Brilliant point! I see it every where, not only amateur commentators on RC, don’t you?

    “I know that you understand this but when communicating, context is important to meaning.”
    Now ain’t that the Truth!

    “learned how important it is to try to be precise in communicating science in order to promote understanding.”

    “…for our own intellectual honesty it is very important that we not appear to be playing their game in the opposite direction. Appearance can be more important than actual intent.”
    True!

    “… my original response to you was misunderstood and deleted, but I don’t see how it could be misconstrued to be that bad.”

    I know how you feel Steve. It may have had nothing at all to do with how well or clearly (or not) you communicated what you chose to say. “Beauty is in the eye of the Beholder”

  38. 138
    Bob says:

    MARodger and Hank Roberts, 132 and 133, I downloaded the RSS Global TLT data from http://images.remss.com/msu/msu_time_series.html, loaded it into Excel, and charted it. The flat for the last 12-15 years is obvious. The UAH charts from Spencer’s website are similar if you start your analysis at around 2004. There may have been a slight increase but it is negligible compared to the surface temperature increases as reported by NASA and NOAA.

  39. 139
    Hank Roberts says:

    For Bob:
    You haven’t taken Statistics 101, and you’re doing what many people do with charts — form their own personal opinion of what they show and assume you’re correct, then base your questions on your personal certainty.

    For the specific question you ask, and the arithmetic you need to do with the data you downloaded, and why one decade isn’t enough, see

    http://moregrumbinescience.blogspot.com/2009/01/results-on-deciding-trends.html

    If I wanted to give you a wrong impression about climate, then, I could use such short records. The range declines as we take longer periods. And then flattens out for trend periods of 252-372 months …

    and

    http://www.woodfortrees.org/

    Please read the notes on things to beware of – and in particular on the problems with short, cherry-picked trends. Remember that the signals we are dealing with are very, very noisy, and it’s easy to get misled – or worse, still to mislead others.

  40. 140
    Bob says:

    Hank Roberts: Taken and aced Statistics 101 and 202. That was a while ago, but I have a reasonably good understanding of the subject. And are you suggesting that you have not formed your “own personal opinion” or that you “assume you’re correct”? It is likely that we both think we are right. We look at the same information, but 1) you find some of it is suspect while I find other of it suspect and 2) we simply draw different conclusions. Only time will tell, but I am confident that in 10 or 20 years we will know that today’s climate science was deeply flawed – probably in more ways than one.

    So anyway, is there a pause or is there not a pause? With article headlines using words like “faux pause” and unqualified statements such as “human-caused warming of the globe proceeds unabated” it sounds as if there has been no pause. But clearly the satellite data shows that, at least, in the lower atmosphere there has been a pause. It is disingenuous to act as if it isn’t happening and to belittle those who point it out, regardless of where it is happening or for how long it has been going on. It’s simply not factual. Whether or not 14 years is long enough to be significant is different issue. BTW, I agree with you when you suggest that it is not. I understand the impact of the different oceanic cycles on temperatures and the climate during relatively short decadal time frames, and I also understand that there are other longer cycles (both oceanic and solar) that create much longer climate cycles; i.e. MWP and LIA, the ice ages, etc.

    So just how long is long enough? If 14 years (2001 to 2015) is not, is 40 years (1975 to 2015)? There are tons of charts out there that show the temperature spike during that time period. We make a huge deal out of the extent of Arctic ice without mentioning that we only have about 36 years of data. That is far from full disclosure and little better than cherry-picking. If we back up to circa 1850 there has obviously been a warming trend since then. But prior to that the preponderance of peer-reviewed studies indicate that there was a general global cooling period that followed a general global warming period that followed a cooling period; each period lasting for hundreds of years. And the Holocene has been generally cooling for the last 8,000 years or so. This is plenty long enough to constitute climate and climate cycles, and if today’s climate is put into the context of the last couple of millennia and the Holocene there is nothing unusual going on. If you are going to cite Mann, Briffa, Jones, et al, or the IPCC as a rebuttal don’t bother.

    But back to my original question. Even if it has been for no more than 14 years or so, why are temperatures in the troposphere declining slightly while temperatures at the surface are apparently increasing? The opposite should be happening, and I can see nothing in the ONI during that time period that explains it. Can someone suggest a reason without implying that I’m an ape or telling me that I can’t understand a set of charts that show clear trends?

  41. 141
    Hank Roberts says:

    PS for Bob, since you’re using Excel — the following is also quoted from
    http://moregrumbinescience.blogspot.com/2009/01/results-on-deciding-trends.html

    Statistical aside: To compute variance, we find the deviation of each observation from the mean, square it, and then add this value up for all observations and divide by the number of observations. (Or use the appropriate function in your spreadsheet.) This is a fundamentally meaningful quantity.

    Do that calculation, using the data you want to understand, to get started.

  42. 142
    MARodger says:

    Bob @138.
    Then it is as I suggested @132. The answer is (1) You cannot read graphs.

    If you had picked on RSS TLT data then it would be a discussion of ‘Why RSS?’ But you add in UAH data which I can assure you exhibits the least “pause”, in truth a pause so minor it is silly to call it a “pause”. It is far less that the surface “pause” that you are happy to interpret not as a “pause” and which instead you say “Surface temperature data indicate that the warming trend continues.”

    Consider the annual data sets of the five records as graphed here (usually 2 clicks to “download your attachment”). If a linear regression for 1979-2014 is compared with the same for 1979-2006, all show a reduced trend over the longer period. NASA GISS & NOAA NCDC, the two you cite @138 give trends 87% & 84% respectively, a minor reduction given the wobbles in the global surface temperatures. HadCRUT4 gives the same result as NCDC. UAH shows a far lower reduction – 94%. It is therefore solely RSS that exhibits anything like a “pause” with a reduced trend of 75%. Yet RSS is supposed to be showing the same thing as UAH.

    I think the evident take-away from this matter is that satellite tropospheric temperature records are less reliable than the surface records. And if you appreciated the difficutlies such measurements have to account for, you would not be surprised.

  43. 143
  44. 144
    tamino says:

    Re: #140 (Bob)

    You may have aced stats 101 and 202, but alas, that really didn’t prepare you to do trend analysis properly.

    Did you know that picking the time at which you start your trend analysis introduces a gigantic bias into the result? Read this.

    You say the troposphere temperature is “declining slightly”. What’s the uncertainty in the estimated trend rate? Did you account for autocorrelation in the noise when you computed that? Do you even know how to do that?

    I know you wanted something other than “I can’t understand a set of charts that show clear trends?” I’m far more interested in telling you like it really is, than in treating your ego with kid gloves. Until you accept the fact that your understanding is mistaken, you’ll have a hard time learning.

    I might have aced Biology 101 and 202 — but if you have a serious medical concern I strongly suggest you consult a real expert, not an armchair diagnostician.

  45. 145

    #140, Bob–

    One wrong click, and a detailed response, point by point, went bye-bye…

    So, the briefer version:

    1) How do you come to pick 2001? It’s too short a time to show statistical significance in this temperature record. Santer et al (2011) found that you need a *minimum* of 17 years. So you’re basing your question on information that’s not meaningful.

    2) As MAR said, it’s not “tropospheric temperature data,” it’s specifically RSS data. If you look at UAH data (which, of course, is based on the same satellite measurements, interpreted however by a different algorithm) you find that the trend since 2001 is remarkably similar to the trend in NASA’s GISTEMP surface data:

    http://woodfortrees.org/plot/rss/from:2001/mean:13/plot/rss/from:2001/trend/plot/uah/from:2001/mean:13/plot/uah/from:2001/trend/plot/gistemp/from:2001/mean:13/offset:-0.15/plot/gistemp/from:2001/trend/offset:-0.15

    Mind you, I wouldn’t make too much of that, since the period of analysis is too short to be very meaningful. (I haven’t compared other surface data sets, so I don’t know just how they’d turn out if you looked.) But over longer time-frames, all the available data sets show pretty good consilience. MAR’s graph shows that, and you can play with the Woodfortrees tool yourself to demonstrate the truth or falsity of my proposition.

    3) If you really care about ‘peer-reviewed studies,’ as you imply, then you can’t afford to diss the IPCC. Their reports are extremely thorough and comprehensive literature reviews. You may disagree with the interpretation, but you can’t afford to disregard the bibliography.

    4) Your whole conceptual frame here is denialist. You aren’t looking at the physical theory (don’t know if you know it), which predates the statistics, you aren’t looking at numerous real-world observations, you aren’t even looking at the whole statistical record, and you aren’t considering alternate hypotheses. You essentially are wearing very, very large conceptual blinkers, and that frankly makes your statement that “I am confident that in 10 or 20 years we will know that today’s climate science was deeply flawed” pretty risible.

    Here’s my attempt to lay out most of the basics in 1500-to-2500 word ‘bits’:

    http://doc-snow.hubpages.com/hub/How-Do-We-Know-That-CO2-Is-Warming-The-Planet
    http://doc-snow.hubpages.com/hub/How-Do-We-Know-That-Humans-Are-Responsible-For-Rising-CO2
    http://doc-snow.hubpages.com/hub/How-Do-We-Know-That-Global-Warming-Is-Affecting-Our-World
    http://doc-snow.hubpages.com/hub/How-Do-We-Know-That-Climate-Change-Will-Be-Mostly-Bad

  46. 146
    Jim Eager says:

    Bob, I’m betting that you did not bother to read the Robert Grumbine post on trends that Hank pointed you to, because if you had you would not have asked “So just how long is long enough? If 14 years (2001 to 2015) is not, is 40 years (1975 to 2015)?” If you had you would know that “how long” is not just some arbitrary time period pulled out of a hat, but is in fact a property of the time series data set itself and that every data set will have it’s own “how long” period.

    If you are not going to make use of elementary and genuinely helpful pointers like Hank’s you are going to continue to suffer rebukes much more biting than the one Tamino gave you this time.

  47. 147
    Matthew R Marler says:

    140, Bob: But back to my original question. Even if it has been for no more than 14 years or so, why are temperatures in the troposphere declining slightly while temperatures at the surface are apparently increasing? The opposite should be happening, and I can see nothing in the ONI during that time period that explains it. Can someone suggest a reason without implying that I’m an ape or telling me that I can’t understand a set of charts that show clear trends? – See more at: http://www.realclimate.org/index.php/archives/2015/02/climate-oscillations-and-the-global-warming-faux-pause/comment-page-3/#comment-626705

    I am sorry to pile on, but the statistical problems are more complex than can be handled by the statistical methods of stats 101-102. The observed data consist of inconsistently measured and incompletely sampled multivariate times series, probably non-stationary, with probably non-linear feedbacks between them (e.g. forest growth vs CO2 concentration.) The problem is not that you can not “understand” charts that display “clear” trends, but that clearly separating any kind of “true trend” from any kind of “background variation” is not straightforward.

    Consider the headline essay by Mike: assuming that the forcing has been correctly modeled, and assuming that the forced part of the temperature record has been a linear function of the forcing, he has shown that the “background variation” has not been correctly quantified. The background variation, including the ocean oscillations, can produce “trends” and “flats” lasting decades, and so there are multiple ways that the physical processes can produce “clear” trends that are independent of any particular causal agent that you are focusing your attention on.

    Santer et al showed that, with a reasonable assumption about background variation, an apparent change in the climate trend (e.g. flatlining surface temperature) would have to persist at least 17 years in order for anyone to draw a reasonable conclusion from it. Mike’s essay here shows how an apparent flat line in excess of 17 years duration could occur without a change in the underlying physical processes.

    Why the difference in apparent trends? Probably right now no one knows an adequate and accurate answer. Not all of the physical processes are known with sufficient accuracy. I am expecting the next 20 years to produce a lot of useful research (ahem, people will produce lots of useful research in the next 20 years), including much improved models of all levels of complexity.

  48. 148
    Matthew R Marler says:

    145, Kevin McKinney: 4) Your whole conceptual frame here is denialist. You aren’t looking at the physical theory (don’t know if you know it), which predates the statistics, you aren’t looking at numerous real-world observations, you aren’t even looking at the whole statistical record, and you aren’t considering alternate hypotheses. – See more at: http://www.realclimate.org/index.php/archives/2015/02/climate-oscillations-and-the-global-warming-faux-pause/comment-page-3/#comment-626722

    I am finding the physical theory to be incomplete. Consider the question/problem that I posed in the March 2015 Unforced Variations: how much do the (dry) advection/convection and evapotranspirative transfers of energy from the surface to the upper troposphere increase as the surface temperature increases? The first two papers that I have seen that address the problem are recent, both in Science, one by Romps et al on changes in lightning strike rate in the US east of the Rockies; and one by Laliberte et al on thermodynamic constraints on the change in power output by the “climate heat engine.” This is one of the fields of science for which I anticipate a lot of new publications this year.

  49. 149
    wili says:

    http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2552.html

    “Near-term acceleration in the rate of temperature change”

    Steven J. Smith, James Edmonds, Corinne A. Hartin, Anupriya Mundra & Katherine Calvin

    Nature Climate Change (2015) doi:10.1038/nclimate2552

    Received 24 June 2014
    Accepted 27 January 2015
    Published online 09 March 2015

  50. 150
    Dan S. says:

    re: 149. “Couple that with the echo chamber that has become the climate science establishment and you have no room for new ideas; no apparent possibility to realize that the fumes you are all breathing might be bad. – ”

    “climate science establishment” Red herring alert! If you read the peer-reviewed science you will know that it is anything but an “echo chamber”. And “new ideas” have to be scientifically valid. Starting with the basics like conservation of energy (which many of the deniers claims ignore). The ones that are valid pass vigorous peer-review. The ones that are not are scarfed up by anti-science deniers who attach themselves to it as if any unscientific report/blogger/novelist/journalist (think George Will) is valid as long as it supports their preconceived beliefs.