Judith Curry and the Ocean Heat Content

Judith Curry has a new post about Ocean heat content uncertainties. The post itself seems to just be the standard uncertainty monster rearing it’s ugly head. Maybe it is too soon to be confident about anything. Maybe there are still uncertainties in the data. Maybe we don’t understand radiative physics as well as we think we do. Maybe feedbacks won’t operate as we think they should. Maybe everything will be fine. Okay, Judith didn’t actually say all of these things, but this seems to be the basic theme of her post. Would I bet my reputation on the possibility that we’ve made some fundamental mistake with regards to the ocean heat content. That maybe the planet isn’t warming as we think it is. I wouldn’t, but I guess if you want to win big you should take the long odds.

So, maybe Judith will turn out the be correct and will have saved us from damaging our economies by trying to mitigate against a non-existent problem. On the other hand, maybe (probably) not. What I was really wanting to comment on, though, was how Judith finishes her post. She says,

All in all, I don’t see a very convincing case for deep ocean sequestration of heat. And even if the heat from surface heating of the ocean did make it into the deep ocean, presumably the only way for this to happen involves mixing (rather than adiabatic processes), so it is very difficult to imagine how this heat could reappear at the surface in light of the 2nd law of thermodynamics.

The first part is really just an illustration of the uncertainty monster. The latter part, however, is – I think – a misunderstanding that I would have expected Judith to appreciate. I’m not actually sure if anyone has actually said this heat could reappear at the surface, but if they have, I don’t think they mean it the way Judith has interpreted it.

I don’t think anyone is really suggesting that the energy going into the deep ocean will suddenly roar to the surface and accelerate surface warming. What they’re suggesting is that the planet has an energy imbalance (we’re receiving more energy than we lose) and – at the moment – more of this energy is going into the oceans than was the case in past decades. Some of this energy appears to be going into the deep oceans. This cannot carry on indefinitely. The oceans are not an infinite heat sink, and the surface has to eventually warm so as to reduce the energy imbalance (we can’t maintain an energy imbalance forever). Hence, we would expect – in the future – the fraction of the energy excess going into the oceans to reduce and the fraction heating the surface (land and atmosphere) to increase, and for surface warming to accelerate. So, it’s not the actual energy quanta that went into the deep ocean that will suddenly reappear, it’s the portion of the energy imbalance currently heating the deep ocean that will suddenly act to heat the surface.

Precisely when this happen is hard/impossible to know. As I discuss in this post the trade winds are nudging up sea levels in the western Pacific. Eventually that water (with it’s energy) will have to run back towards the East. Also, the longer it takes, the larger the energy imbalance will be and the faster the surface warming will be. So, yes, the energy going into the deep ocean will likely stay there (for the foreseeable future, at least) but basic physics tells us that we can’t continue to sequester energy in the deep ocean and eventually the portion of the energy excess that is currently going into the deep ocean will have to start heating the surface, and we will have to see accelerated surface warming (unless, as I said at the beginning, our understanding of radiative physics turns out to be wrong).

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35 Responses to Judith Curry and the Ocean Heat Content

  1. OPatrick says:

    it is very difficult to imagine how this heat could reappear at the surface in light of the 2nd law of thermodynamics

    On occasion when I’ve seen a similar argument made in the past I’ve argued that the ENSO cycle demonstrates that it can happen. Is this correct or is the effect entirely unrelated?

  2. JCH says:

    Judith Curry wrote this at Climate Etc. in response to a comment I made there:

    “Actually, not true, KT was arguing from a 1st law of thermodynamics perspective
    (neglecting the 2nd law) as per a conversation I overheard.” – Dr. Curry

    I take it to mean she believes Trenberth thinks energy diffused into the deep ocean will somehow reappear at the surface as warming.

  3. OPatrick,
    Certainly an El Niño event can bring warm water to the surface, the energy from which can then heat the land the atmosphere. I don’t think, however, that this energy was necessarily ever in the deep ocean. It’s possible of course that energy from the deep ocean could make it back to the surface, but we don’t need that to happen in order for surface warming to resume.

    That was what I understood from what Judith Curry had said. It would be interesting to know what Kevin Trenberth really thinks about this. In some sense, it doesn’t really matter (I think). We don’t need this energy in order for surface warming too accelerate. All we need is for a smaller fraction of the energy excess to go into the deep ocean (if it is indeed currently doing so). Of course, if some of the energy were to be advected to the surface then it could act to heat the land and atmosphere, but it was my understanding that it is the distribution of the energy excess (i.e., how much is going into the different parts of the climate system) that matters, not whether or not some heat that made it to the deep ocean ever comes back out again.

  4. verytallguy says:

    The original quote appears to be here.


    Which appears to contradict your “I don’t think anyone is really suggesting that the energy going into the deep ocean will suddenly roar to the surface and accelerate surface warming.”

    Like you, however, I’d be amazed if this is what Trenberth really thinks. Rather the rate of mass and hence heat transfer to the deep ocean has increased, masking the true energy imbalance. And when that rate returns to “normal” the rate of surface heating will accelerate, hence coming back to haunt us.

    I don’t think the rate of ocean heating, even over 0-700m, is anywhere near sufficent to make any material difference to the temperature of upwelling water from the ocean (except on millenial timescales), which is the alternative interpretation.

    See http://www.realclimate.org/index.php/archives/2011/10/global-warming-and-ocean-heat-content/comment-page-2/ for an RC thread (including RP Srs views)

  5. JCH says:

    He thinks warming will come back to haunt us.

    “The heat will come back to haunt us sooner or later,” – KT

    But to jump to he is suggesting violating the 2nd law is just plain imbecilic. He means simply that warming will resume. People were suggesting then that global warming had stopped; as in, additional ACO2 no longer worked. People took him to mean the heat sequestered in the deep ocean, the missing heat, was going to jump back out. As though that was the only way warming could resume.

    In terms of ENSO/, some of the massive pools of water lying below the SST layer that are moved around by ENSO are warm, and in that sense some of the sequestered warmth can reappear in the SST layer and become a part of the surface air temperature.

  6. VTG,
    Thanks. I can see why some might interpret it that way, but I would be surprised if KT actually meant that specific energy, rather than the energy associated with warming the deep oceans (i.e., that portion of the energy excess). I presume that’s why he said “so to speak” in the middle of the quote. Obviously, we can’t read KT’s mind, but I would agree with what JCH’s is saying. He probably just means that warming hasn’t really stopped (because the energy is going into the deep oceans) and will have to, at some stage, resume.

  7. VTG,
    That RC thread is very interesting. Partly because it’s interesting to discover that it seems quite common that Pielke Sr. redefines terminology or chooses to use non-standard terminology in discussions. Also interesting because Gavin was defending global warming as a term that referred only to surface temperatures. I’ve often felt that this was problematic in that it allowed people to claim it had stopped based only on a pause/slowdown in surface warming. Of course, if everyone has a good understanding of all the evidence and understands what we mean by various terms, it wouldn’t be problematic, but that is typically not the case.

  8. verytallguy says:


    I once had a short interaction with RPS on SKS where he was arguing, in apparent seriousness, that the OHC data was good enough to define the Earth’s energy balance on a monthly basis (!)

    This was, I think, at the point where Argo data was relatively immature and seemed to be pointing to cooling rather than warming.

    I recall that I didn’t maintain civility in a way I’d be proud of. In the unlikely event RPS is reading this, my apologies.

  9. VTG,
    I had an interesting exchange here with RPS in which he seemed to be arguing that there was no evidence for any feedbacks operating. I was arguing that you can’t explain a 0.9oC surface temperature rise, a 2.2 Wm-2 change in anthropogenic forcing, a small change in solar forcing and a 0.6 – 0.9 Wm-2 energy imbalance today, without feedbacks having operated. We didn’t reach agreement, but it was reasonably pleasant 🙂

  10. JCH says:

    OPATRICK – I think your argument is flawed in that you are suggesting a violation of the 2nd law. ENSO does not reassemble diffused energy from the abyssal oceans.

    I have been reading papers about the Peru-Chile Trench. In papers specifically about the trench they always call it a place of upwelling. I’m too stupid to really understand what they mean, but I am curious as to whether any water from the bottom layers of the Peru-Chile Trench ever makes it to the surface during a strong La Nina event. Because then extremely cold water slightly warmed by the sequestration of energy during the pause would be coming back to haunt us!

  11. AnOilMan says:

    What exactly is the uncertainty for ocean heat content? Can anyone refer me to a good paper on this?

    I’ve made a point of saying that the use of sparse data to predict ocean thermal\salinity profiles is old science, and well in the realm of applied sciences and engineering.

  12. AoM,
    Someone posted a link to a paper that described the errors in the OHC quite well, but I can’t seem to find it. If I do, I’ll post it again. You could try Levitus or Balmaseda though. Both are recent (2012 I think).

  13. JCH says:

    Lyman and Johnson

    Also, I think Karina von Schuckmann has some recent work on ARGO.

  14. JCH says:

    I actually think Roger Pielke Sr. is a stickler for precise language, and I have learned a lot from reading his blog with the “radical” commenting policy. I believe here in 2003 he is describing a pause in surface warming:If the heat actually remains within the earth system in the deeper ocean, for example, while the heat content of the remainder of the heat reservoirs in the earth system remains unchanged,

    It’s all very Trenberthian. Also, note he is not overly concerned about needing a mechanism for drilling heat into the deep ocean.

  15. JCH,
    He may well be a stickler. I’ve only really encountered him a couple of times and in the one discussion I had with him we did seem to spend a lot of time disagreeing about what various terms meant – feedback being one. Could be that I was using it incorrectly, but I did try to explain what I meant.

  16. Joshua says:

    Please excuse my ignorance (and put on your dumming down caps so that you can speak in terms I might have some hope of understanding)….

    Why would the concept of heat/energy transmitted into deep ocean water, that was then brought to the surface through phenomena such as an El Nino, violate the 2nd law of thermodynamics?
    Is it that the deeper water brought closer to the surface, although warmed in comparison to its earlier state, would not be displacing colder water closer to the surface?

  17. Rob Painting says:

    In addition to the Lyman & Johnson (2013) paper see also:

    Abraham et al (2013) &

    Von Schuckmann et al (2013).

    Contrarians are scraping the bottom of the barrel now……

  18. > Maybe it is too soon to be confident about anything. Maybe there are still uncertainties in the data. Maybe we don’t understand radiative physics as well as we think we do. Maybe feedbacks won’t operate as we think they should. Maybe everything will be fine.

    In Judy’s comment section, Bart R focuses on something more specific:

    The entire framing of this uncertainty shell games amounts to no more than that of the anti-scientific fellows (and often Fellows) over a century ago who imagined their brilliant riposte to Rutherford’s work, that microscopes lacked the resolving power to directly observe atoms, therefore Rutherford’s conclusions could be dismissed, held water.


    PS: Thank the Lord of Climateball that the Twitter login is back!

  19. Oh, and NG just won the Internet:

    Via Joshua, it shall not go without saying.

  20. Joshua,

    Why would the concept of heat/energy transmitted into deep ocean water, that was then brought to the surface through phenomena such as an El Nino, violate the 2nd law of thermodynamics?

    The only real issue is how it gets from the deep ocean to the surface. It can’t diffuse because the temperature gradient is wrong (that would violate the 2nd law of thermodynamics). However, if there are upwellings – as JCH mentions above – then if you physically move water from the deep ocean to the surface then that would bring the energy with it. The issue, though – I think – is that the temperature drops with depth and so 1m3 of water at 2000m has less energy than 1m3 of water at the surface (typically at least). Therefore if you advect water from depth to the surface and replace water already at the surface (which then goes deeper) the total energy at the surface goes down. So, it’s hard to both bring the energy back to the surface (from depth) and increase the energy/temperature of the surface. At least, I think that is the issue.

  21. Willard,
    Yes, I noticed Bart R’s comment about that, which also included a question as to whether or not Bayesian statistics. I don’t really myself, but am not ashamed to admit that 🙂

  22. Joshua says:

    Anders –

    Thanks. I actually understood that. :-}

  23. Joshua,
    Let’s hope I was roughly correct then 🙂

  24. John Mashey says:

    As to what Trenberth currenlty thinks (as opposed to secondhand or more), try Trenberth, K. E., J. T. Fasullo and M. A. Balmaseda: 2014: Earth’s energy imbalance. J. Climate, 27, doi: 10.1175/JCLI-D-13-00294. That gets referenced in various threads, including by JCH, I think, but people might want to study that.

    Now, this is classic good science:
    here are improvements in what we know
    this is what we don’t know, with ideas on how to improve

    rather different from: until we know everything we know little

  25. John,
    Thanks. I’ve seen that paper. Indeed very good.

  26. AnOilMan says:


    A hiatus is a bad thing. If this is all a natural cycle, then temperatures should be declining… a lot.

    Consider the other statistic, for the number of temperature records being set. The number of records being set should be exponentially decreasing, not holding still or increasing.

  27. izen says:

    @-“All in all, I don’t see a very convincing case for deep ocean sequestration of heat.”

    Judith Curry makes a case for the OHC data to be patchy, short term and prone to unknown sources of bias. She also compares the earlier and patchier, shorter and possibly biased OHC data with the later, more comprehensive, later data that had attempted correction of biases found in the earlier data by new observational and modelling methodologies.

    The fact that the later OHC data is more ‘alarmist’ than the earlier, patchy corrected data seems to be interpreted, or at least there is an implication, that this apparent observational confirmation of the hypothesis that the slow rate of current surface warming is the result of an increased sequestration of energy in the deep ocean is rather convenient.

    That discrepancy, or improvement in the data over time, is taken as increasing the ‘uncertainty’ with which the whole OHC data should be regarded. And the present increase in certainty about OHC a bit of wishful thinking.

    But if the uncertainty in the OHC data makes it less persuasive as support for the hypothesis of deep ocean sequestration, it also makes the observed magnitude uncertain symmetrically.

    The case must be just as unconvincing that LESS energy has been sequestered as it is unconvincing that the claimed amount or more has entered the deeps.

    The argument Judith Curry makes from the rate of sea level rise is that because OHC is responsible for around 1/3 of present rates of around 3mm/yr, and the rate in the 1930s-1940s was similar with less melting ice then the amount of energy going into the oceans then must have been greater than now because it caused more expansion per year.

    I will of course take Judith’s word for it that there was much less ice melt when the rate of sea level rise was last as fast as it is now. {g}

    Of course melting ice to raise sea level puts a comparable amount of energy into the oceans with very little temperature change. So Judith Curry appears to have identified two periods about ~60 years apart when the energy imbalance went preferentially into raising sea level. That there must have been a net flow of energy into the oceans during both the 1940s and the present is a consequence of the energy required to raise sea level by 3mm by ANY means.

    I suspect however that the deeper purpose of highlighting the uncertainty in OHC rates of gain is to imply that there is no energy imbalance that requires an explanation.

    @- “And even if the heat from surface heating of the ocean did make it into the deep ocean, presumably the only way for this to happen involves mixing … so it is very difficult to imagine how this heat could reappear at the surface in light of the 2nd law of thermodynamics.”

    At best Judith Curry is being ironic, employing a rhetorical device, the litotes. Given she describes a process by which the energy added to surface water is distributed within a greater volume of deep cold water so that the resulting mix has greater entropy it is not just ‘difficult to imagine’ how that energy might reappear at the surface as ‘heat’.. It’s scientifically impossible.

    But it essentially a strawman.
    By suggesting that some CAN imagine that energy that is distributed into the deep ocean could re-emerge to warm the surface and pointing out that this would contravene the 2LoT {sarcastically?} she implies that THIS is the mode of warming that the ‘warmists’ warn about.

    But the problem is that putting energy into the oceans, either by raising the temperature of vast volumes of cold deep water or melting land ice DOES cause a slowdown in the rise in surface temperatures.

    IF(!?) the energy imbalance exists then the only way it can re-balance is for surface temperatures to rise so that emission can increase to correct it.
    If Judith’s stadium wave effect causes large amounts of energy to go into the oceans for very little temperature change every ~60 years then the total amount of global warming will still not be altered. The rate of rise may not even be slowed much. It will instead consist of periods of slow rise {half the ‘all thing being equal’ rate} and then three decades of very rapid rise.
    Double the ‘all things being equal’ rate.

    Or have I got something completely wrong here?

  28. It’s really a terrible, error-riddled post by Curry. We’ll have a comprehensive response on SkS with input from Trenberth, who no, has never said that deep ocean heat will suddenly return to the surface. You interpretation is exactly right, ATTP.

  29. jyyh says:

    öf course the heat in the deep ocean can come to the surface again. all that’s needed is a hydrostatically driven upwelling event breaking through the halocline and thermocline, on a high latitude that’s below freezing on the surface, so the normal downwelling is reverted so it keeps the ocean from freezing. This could happen f,e, on Barents or Ohotsk Seas in 1998. Granted, there are probably warmer layers in between like the one under the less saline dome of water under the arctic ice cap that are more likely to do it but surely the intention is not to claim that what goes down must stay down for all eternity,

  30. jyyh,

    but surely the intention is not to claim that what goes down must stay down for all eternity,

    Certainly not. You’re right that water can physically move around in the ocean and will take the energy with it. The main point is that this doesn’t need to happen to faster surface warming to resume. That can happen simply because of a change in the distribution of the excess energy that we’re receiving.

    Something to bear in mind though (I think) is that water is virtually incompressible. So if I bring 1m3 of water from depth to the surface, then I have to displace 1m3 from the surface. Since 1m3 at the surface will normally have more energy than 1m3 at 2000m, simply bringing water up from depth doesn’t mean that one will increase the total energy at the surface.

    Thanks. It was rather error riddled and rather amazing that someone can base their view of what another scientist has said on a few lines in a newspaper article.

  31. izen,
    That seems to be pretty much how I see it too. Have you read John Nielsen-Gammon’s article that Joshua links to above?

  32. jsam,
    Yes, it seems that maybe I should consider becoming blunter in my assessments 🙂

  33. Pingback: Illustrating error analysis | And Then There's Physics

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