Assessing global warming

A couple of years ago I wrote a joint post with Roger Pielke Sr that discussed assessing anthropogenic global warming. The post basically used changes in ocean heat content to assess anthropogenic global warming. The basic idea (which is not a new one) is that anthropogenic global warming is driven by our emission of greenhouse gases (mainly CO2) into the atmosphere, which acts to reduce the outgoing energy flux. This produces a planetary energy imbalance and means that energy will accrue in the climate system until it returns to energy balance via an increase in surface temperature.

One reason I thought I’d write about this is that I came across an article called taking the pulse of the planet, which John Abraham (one of the authors) also discusses in this Guardian article. This article also discusses using ocean heat content to assess anthropogenic global warming. A key point is that most of the excess energy associated with the planetary energy imbalance goes into the oceans, with only a small fraction heating the land/atmosphere. Therefore, surface temperatures show much more variability than ocean heat content measurements.

Credit: Cheng et al., EOS, 2017


What this means, as the table on the right shows, is that it may take more than 20 years for a trend to emerge from the noise in surface temperature data, but it only takes about 4 years if you consider ocean heat content (OHC), or sea level rise (SLR), data. Therefore, ocean heat content (and SLR data) are more robust indicators of global warming, than surface temperature data.

The authors of the article therefore recommend that

that both the EEI and OHC be listed as output variables in the CMIP6 models, in addition to SLR and GMST.

where EEI is the Earth’s energy imbalance, and GMST is global mean surface temperature.

I think the above is quite an important suggestion, because I do think it’s important to stress that anthropogenic global warming (AGW) is really about energy accruing in the climate system due to us emitting greenhouse gases into the atmosphere; it’s not just about rising surface temperatures. The surface temperature does, of course, rise as a consequence of this increasing energy (and is the way in which the system returns to energy balance), but assessing AGW should probably be done by considering the overall energy balance, rather than by simply considering surface temperatures (from which it is much more difficult to extract a signal from the noise).

Of course, I’m not arguing that it’s not also important to consider surface temperatures; we do live on the surface and – of course – want to understand how surface temperatures are rising, and will continue to rise, in response to increasing anthropogenic forcings. However, by considering the overall change in energy we should get a better sense of the rate of AGW and might avoid claims – based on looking at noisy data over short time periods – that global warming has “paused”. Okay, the latter is probably naive, but I’m not completely without hope.

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69 Responses to Assessing global warming

  1. Something that I was wondering was what one would conclude if one simply assessed a model on the basis of how well it matched the overall rise in energy (maybe using OHC as a proxy) if we also knew that that model matched the known change in external forcing. If it matched it well, could one conclude that it would also probably match the surface temperature rise? One reason you might think that it should is that if you know that it matched the overall change in energy and know that it matches the change in external forcing, then if it didn’t also match the change in surface temperature (which will act to mediate the planetary energy imbalance) it shouldn’t then match the overall change in energy. However, I suspect that there are too many variables for this to be the case. A large change in surface temperature with a strong feedback response could produce the same planetary energy imbalance as a smaller change in surface temperature with a smaller feedback response. There’s also the pattern of surface warming to consider. So, it’s not simply enough to consider the change in OHC (as a proxy for the planetary energy imbalance). However, this would still be a very important indicator of global warming.

  2. G. Poulos says:

    Since the idea of global warming still has an excellent chance of being bullshit you should stick to cherry picking your data from surface temperatures. I think if you start using ocean temp and sea level rise you are gonna shoot yourself in the foot. You have alot of money, “religion” and political power at stake so you should stick with what’s working.

  3. Steven Mosher says:

    OHC as a standard metric would be a great idea. The other thing is it is probably time for the IPPC to start winnowing the models that can make it into the final report. If your simulation that starts at 1850 can’t match (within some measure) OHC between 1985 and 2015, then no cookie.
    or you could just consider the top X % of models depending on their OHC error.

  4. G.Poulis,
    More than happy start putting more emphasis on OHC and SLR. The chances of AGW being bullshit really are vanishingly small. A great deal of very basic – and very well understood – physics would need to be wrong for that to be the case.

  5. Steven

    The other thing is it is probably time for the IPPC to start winnowing the models that can make it into the final report. If your simulation that starts at 1850 can’t match (within some measure) OHC between 1985 and 2015, then no cookie.

    Yes, I think it’s quite hard to eliminate models on the basis of surface temperatures only, but I suspect that not matching well the change in OHC would be a stronger way of eliminating outlier models. Be interesting to get the views of someone who works more closely with these models.

  6. Steven’s comment reminded me that a number of climate modes are tuned to a radiative imbalance (either present day, or pre-industrial) so you would (I think) then expect that matching the observed change in OHC would be a good way of testing models (assuming that they have followed a forcing pathway that actually matches what happened in reality).

  7. Like with temperature where we look at the warming, for OHC one would look at its increase for which we only have good estimates for the recent decades. If there are estimates of the increase in OHC since 1850, I would expect them to have too much uncertainty to be useful.

    I would not remove scientific climate models from the CMIP archive for any reason. That is not the job of CMIP. And especially not modelling the changes right. If a model does not get this right that is important information and something that needs to be studied and people studying this need access to the data in the archive.

    One could exclude them from estimates of future warming, climatic changes or from impact studies. That is best done by the researchers making such estimates and not by a CMIP dictator.

    Even for impact studies, I would personally prefer to remove models based on how well they model specific processes (that are important for those impacts) or based on how well the simulate the state of the climate (spatial map of the temperature, the diurnal cycle, the annual cycle, similar characteristic of the cloud fields, etc.). For example, some models have quite simple sea ice modules, someone interested in Arctic climate change may want to remove such models.

    If you remove models for not getting the changes right, it becomes fitting/statistics, the climate models are there for the physics and it is the physics that gives confidence that extrapolation into the future makes sense.

  8. Victor,
    Yes, those are good points. We mainly use models to try understand parts of systems and so there may be some that are useful for one aspect, but don’t do as well on others. As you say, though, we may use how well they match something like the OHC to decide which models we use for estimates of future warming, but that doesn’t necessarily mean that we would not use the other models for other things.

  9. Clear and concise. I appreciate that.

  10. Bob Loblaw says:

    For the “how many years? question, I often refer back to an old post by Robert Grumbine:

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

    The key element to understand is that the length is a characteristic of the data, not the method.

    As for Pielke, I am forever biased with respect to his knowledge and use of ocean heat content, as the result of his participation is this thread over at RealClimate. He seemed to have a really hard time understanding the difference between “flux” and “flux divergence”. Maybe he’s figured it out since then, but I had expected better from someone with his background. (I joined in on comment page 3.)

    http://www.realclimate.org/index.php/archives/2011/10/global-warming-and-ocean-heat-content/

  11. Steven Mosher says:

    “Steven’s comment reminded me that a number of climate modes are tuned to a radiative imbalance (either present day, or pre-industrial) so you would (I think) then expect that matching the observed change in OHC would be a good way of testing models (assuming that they have followed a forcing pathway that actually matches what happened in reality).”

    Ya thats what I was thinking. Maybe RayP or gavin would weigh in. I know a while back gavin seemed to be of the opinion that folks needed to move beyond the democracy of models, but a ‘scoring” approach or weighting approach was TBD.

    A simple rank by OHC error might be an instructive first step.

  12. Steven Mosher says:

    “If you remove models for not getting the changes right, it becomes fitting/statistics, the climate models are there for the physics and it is the physics that gives confidence that extrapolation into the future makes sense.”

    Anyone then can submit a model no matter how simple or bad and all it does is increase the range or envelope of results.

    For a report on the state of the science, Yes, submit all the data.
    For a report on the best science, the dictator is a good idea.

  13. Steven Mosher says:

    Let’s put Victor’s idea to an extreme test.
    Model X gets every metric perfectly right.
    1000 other physics models are wildly off.

    are these 1000 important information? in the most benign way they are. failure is a good teacher.
    But Rewarding failure my publishing those results in a summary of the science? huh?

    Look. The results of models done for CMIP are not peer reviewed. They are submitted to the archive and IPCC report uses them. as is. What I’m suggesting is a simple automatic form of peer review or sanity check. Its not like the data is disappeared.

  14. Steven,
    I think Victor’s point is more sophisticated than simply “keep all models”. I think it is more that there might be models that would fail the test but that would still be useful in some circumstances.

  15. If the physics of these 1000 models is within the range of our understanding of the climate system it would be hugely important to see that they are “wildly off” when it comes to the outcome. That gives us important information on how well we understand the problem.

    Just because your one model performs well for the past does not men that it will perform well for the future. If the physics would not be able to constrain the past, that would mean that the future projections have a large uncertainty.

    If the b-list scientists of Scott Pruitt’s Red Team make a model that does not include in the influence of CO2 in its radiative transfer computations, by all means remove such a dud. But models with good physics that do not model the past well, that is the stuff scientific dreams are made of. Nothing is more boring than getting a yes, you want to get the no, 1000 times no even better.

  16. Let’s not be naive. If your model is relegated to the ‘archive only’ bin there will be real world consequences in funding and research. Yet, the relegated model may well have more correctly stated the physics, but did a poorer job in fine tuning via parameterization. And I’m sure we’re all familiar with situations where the correct answer was arrived at through a multitude of errors that serendipitously cancelled each other out. It would seem foolish just on these rounds to chance losing not only a good model, but perhaps even the ‘best’ model, due to little more than luck in the rankings.

  17. angech says:

    ATTP.
    First comment is that all data sets are of some value in assessing anthropogenic global warming.
    Second is that global warming is about rising surface temperatures at some stage, at some time otherwise why bother.
    There are different components and different warming responses that make it impossible to state at any one time this component or summation is the best measure of global warming.
    Surface, stratospheric, TOA and OHC are all valid estimates of the extent of of global warming though all suffer from some degree of impracticability at the actual time of being recorded.

    So first beef is the unconscious desire to change units when one’s previously acceptable measure stops living up to its desirability.
    This argument of using OHC crops up from time to time but usually when the surface temperature argument takes a pause. Here we are with falling surface temperatures since the El Nino so suddenly surface temperatures become a flighty, variable, unreliable, not quite up to the mark way of looking at global warming.

    Not that OHC is not a more stable, slower responding and overall better concept. It’s good points.
    It is just not user friendly or useful usable to put it bluntly. Its bad point. One of many. I just love it as a party topic, the OHC went up 0.00001 percent yesterday from last week.

  18. angech,
    I actually can’t work out what you’re trying to get at in your comment.

  19. Oneill,

    Yet, the relegated model may well have more correctly stated the physics, but did a poorer job in fine tuning via parameterization.

    Yes, I think that’s right. However, that’s one reason why there was a suggestion that model users start being clear about how they’re tuning their models. That way you can not only know what was done, but maybe also come up with a set of properties that are typically used to tune these models.

  20. JCH says:

    P Sr.’s obsession with using OHC, and you can follow this on his blog, had to do with invalidating GISS Model E. So angech has it backwards. Pielke thought OHC was not going up. Willis firsthand a paper that found cooling in the oceans. Wong disputed it and Willis took another look and found a problem. JK Willis and Trenberth were right there with P. Sr. in the bog discussions. That is how JK Willis got the insanely wrong reputation of being a denier; because he disagreed with Trenberth about ARGO. A few months ago a denier type actually recommended JK Willis and Takmeng Wong for Curry’s red team.

    And the surface air temperature, after the 14-16 El Niño, remains shockingly warm. He’s just massively confused, as always.

  21. Bob,

    As for Pielke, I am forever biased with respect to his knowledge and use of ocean heat content, as the result of his participation is this thread over at RealClimate. He seemed to have a really hard time understanding the difference between “flux” and “flux divergence”.

    I read some of the RealClimate comment thread last night. Quite bizarre. There was a somewhat similar comment thread here in which Roger (who has been using energy balance models) didn’t seem to get that you need to know how the system heat uptake rate changed over some time interval, not the average over that time interval. In a sense, that was why I found writing the post with him quite interesting, because we didn’t make that same mistake. Roger and I have, however, since fallen out and he doesn’t really talk to me anymore.

  22. Steven Mosher says:

    “Steven,
    I think Victor’s point is more sophisticated than simply “keep all models”. I think it is more that there might be models that would fail the test but that would still be useful in some circumstances.”

    I can always construct a way in which things are useful.

    Look, Lets keep it Simple.

    In doing IPCC attribution studies models that have too much drift in the spin up are excluded from the analysis. ( at least in AR4)

    Should that be continued or stopped?

  23. If you have a good reason to exclude a model for a specific study that can naturally be justified. That is very different from not letting the model run into the CMIP archive.

    Drift without forcing will often be a problem. That is a real problem and different from not matching estimates of past warming.

    oneillsinwisconsin: “Let’s not be naive. If your model is relegated to the ‘archive only’ bin there will be real world consequences in funding and research. Yet, the relegated model may well have more correctly stated the physics, but did a poorer job in fine tuning via parameterization.

    There is no archive only bin. There are models that continually under and overestimate last century warming. That is fine and they should be used. There should be no punishment for that. Would we run reality again that new realisation could continually under and overestimate last century warming.

    Wasn’t the warming of the GISS model above average? (Or the climate sensitivity?) Fake sceptics looking at the outcome complained about that, if I recall correctly. Scientists did not, it is a perfectly fine model.

  24. Steven Mosher says:

    “The other thing is it is probably time for the IPPC to start winnowing the models that can make it into the final report.”

    1. You submit your results as always to the archive.
    2. Folks apply a test. .
    3. Write final report

    What I’m suggesting is no different than applying a drift test.
    Information isnt lost. The data is still there.

  25. Bob Loblaw says:

    ATTP: “Roger and I have, however, since fallen out and he doesn’t really talk to me anymore.

    Around the same time as his participation at RC, Roger Pielke Sr. also participated in some discussions at Skeptical Science. SkS wrote a summary post:

    https://skepticalscience.com/pielke-sr-sks-dialogue-final-summary.html

    My comments #36, #48, and #52 sum up more of my view. He wants fans, not debate. Oddly, as I re-read comments from almost six years ago (especially #48), I see similar issues (climatologically-speaking) to what is being discussed here – signal to noise ratio, detection of changes…

  26. izen says:

    @-BobLudlaw
    “Oddly, as I re-read comments from almost six years ago (especially #48), I see similar issues (climatologically-speaking) to what is being discussed here – signal to noise ratio, detection of changes…”

    Yes, the criteria for a AGW metric are the same.
    What has changed is that we have over 5 years more OHC data, and better ways to process it.

    http://advances.sciencemag.org/content/3/3/e1601545.full

    Another thing that has changed, is how dated all that discussion of the ‘pause’ or global warming having stopped, looks from post 2016. The graphs of OHC in the paper above confirm the process of energy flux continued uninterrupted.

    But did I just spot a new pause meme in angtech’s suggestion that OHC is favoured because there has been no warming since… last year?

  27. Bob Loblaw says:

    Izen:

    Yes. As I said in the old post at SkS:

    “The network to measure OHC is also relatively recent, so there are very severe limitations on what we can do with it now, due to the short record. Keep it going, for sure. As the record grows in length, it will become more and more valuable.”

    As you say, improved processing, including additional sources of data to help guide the processing, is also a factor. Of course, the denialati all look at that as “fudging”. Scientists look at it as “learning”.

  28. Steven Mosher says:

    Bali maybe having an eruption.

    gather the popcorn if it leads to cooling.

  29. Steven Mosher says:

    “My comments #36, #48, and #52 sum up more of my view. He wants fans, not debate. Oddly, as I re-read comments from almost six years ago (especially #48), I see similar issues (climatologically-speaking) to what is being discussed here – signal to noise ratio, detection of changes…

    48 was a good comment.

  30. gather the popcorn if it leads to cooling.

    Yes, it could be interesting.

  31. Andrew Dodds says:

    Yes, there’s a slight predictability there. Major eruption -> 3-4 years of cooler-than-trend temperatures -> 6-7 years of ‘global warming has stopped/ice age cometh/models didn’t predict unpredictable event’ rhetoric. Which would take us into the mid-2020s.

    In a sane world, the climate effects of a major eruption would be seen as nature’s way of giving us more time to get our house in order…

  32. angech says:

    “Bali maybe having an eruption.”
    I thought volcanoes were not supposed to be important, and that everyone would realise there was no impact on cooling, just like El Nino’s do not cause global warming.
    Over in the Arctic everyone was cheering for a hurricane or 2 to breakup the Arctic ice to get a new low this year. So only fair if people cheer on one one side effect of weather that they boo the other, not scientific but fair.

  33. angech,

    I thought volcanoes were not supposed to be important, and that everyone would realise there was no impact on cooling, just like El Nino’s do not cause global warming.

    Okay, here’s an opportunity to clear up a misconception. Over long timescales, the volcanic forcing is quite small and, therefore, volcanoes are indeed not very important when it comes to projecting long-term warming. However, a volcanic eruption can eject a large amount of small particles into the upper atmosphere. These small particles reflect sunlight and act as a coolant. A large eruption could reduce global surface temperatures by a few tenths of a degree. However, these small particles precipitate out of the atmosphere relatively quickly – on the timescale of years. Therefore, volcanic cooling is a short term effect (lasting a few years) and will have little impact on the long-term warming trend.

  34. angech says:

    Would much more prefer to comment on VV comments eg
    “If you remove models for not getting the changes right, it becomes fitting/statistics,”
    and his other comments which made a lot of sense to me, sorry Victor.
    contrasted to this gem,

    “Let’s put Victor’s idea to an extreme test.
    Model X gets every metric perfectly right.
    1000 other physics models are wildly off.
    are these 1000 important information?”

    Any model that gets every metric perfectly right in a game that has a huge amount of unpredictability in it at the micro level is basically impossible. Hyperbole but there one goes. Wildly implausible is just far far too soft. Such models do occur, just like Bridge hands with 13 spades occur far more regularly than they ever could by chance.
    The trouble is we do have these sort of hands occurring in a slightly different fashion. We have models that refuse to model the dark side. This came up in a comment by Steven on a previous blog where he mentioned the lack of acceptable weather terms. More pertinently the fact that no model run ever throws to the low side of the average is just as disconcerting for independent observers [me] and wildly rabid skeptics as is a perfectly correct model but, sigh, no-one notices or cares.

  35. angech says:

    ATTP thanks.
    I agree with your comments on volcanoes above totally.
    VV seems spot on with his model comments as well.

  36. verytallguy says:

    Over in the Arctic everyone was cheering for a hurricane or 2 to breakup the Arctic ice to get a new low this year.

    [wearily] Citation required [/wearily]

  37. verytallguy says:

    the fact that no model run ever throws to the low side of the average

    [wearily] Citation required [/wearily]

  38. Climate models always do better with a known forcing. Where they do worse is if they rely on (1) “Unforced Variations” (to borrow the RealClimate term) or (2) if the source of the forcing likely exists but hasn’t been determined.

    Where they do best is if the forcing is known. Examples of this include
    (a) daily cycle -> solar origin
    (b) seasonal cycle -> solar origin
    (c) volcanic disturbances -> upper atmosphere aerosol origin
    (d) long-term warming -> GHGs
    (e) ocean surface tides, ENSO, QBO -> lunar plus solar gravitational

    The variation that has yet to be tracked down is the ~60 year variation in global temperature that has been variously linked to PDO, AMO, and LOD. The Length-of-Day connection established by researchers at NASA JPL is most intriguing:

    Dickey, J. O., S. L. Marcus, and O. de Viron, 2011: Air temperature and anthropogenic forcing: Insights from the solid Earth. J. Climate, 24, 569–574, doi:10.1175/2010JCLI3500.1.

    What causes this variation in LOD is tough to pin down.

  39. John Hartz says:

    And Then There’s Earthquakes…

    The Weird Way That Climate Change Could Make Earthquakes Worse by Kristin Hugo, Newsweek, Sep 24, 2017

  40. Magma says:

    Over long timescales, the volcanic forcing is quite small and, therefore, volcanoes are indeed not very important when it comes to projecting long-term warming. — ATTP

    On the very long term, volcanoes are critically important to the regulation of Earth’s climate, as this is the only way that CO2 sequestered in carbonates subducted into the lower crust or upper mantle can be released back to the atmosphere. I can’t recall a good reference off the top of my head, but the most persuasive hypothesis of how icehouse Earth was able to emerge from widescale continental glaciation seems to be the gradual increase of atmospheric CO2 outgassed from volcanoes and not consumed in silicate rock weathering due to low temperatures and ice-covered continental rock and soil.

  41. On the very long term, volcanoes are critically important to the regulation of Earth’s climate, as this is the only way that CO2 sequestered in carbonates subducted into the lower crust or upper mantle can be released back to the atmosphere.

    Indeed, as I understand it, it is essentially the balance between outgassing via vocanoes and uptake by the slow carbon sinks that sets the long-term atmospheric CO2 level.

  42. Magma says:

    To use the more correct term, I meant Snowball Earth (the full pole to equator ice and snow cover interpreted for the very late Proterozoic) rather than Icehouse Earth (atmospheric, orbital and tectonic conditions permitting high to mid-latitude glaciation, as in the Quaternary).

  43. Magma says:

    it is essentially the balance between outgassing via volcanoes and uptake by the slow carbon sinks that sets the long-term atmospheric CO2 level

    Yes, with the understanding that there can be both organic and inorganic carbon sinks involved. And even the ‘inorganic’ sinks are mediated by organic processes to a surprising degree. Once present, life gets its mischievous little fingers into everything.

  44. SM writes: “Bali maybe having an eruption.”

    Bali’s Mt Agung has played a crucial role in the theory of AGW. It was by examining the 1963 Mt Agung eruption that James Hansen, and probably the rest of the scientific community, got verification that climate models are actually getting the radiative physics correct. And Hansen’s/NASA’s Model Zero GCM (1970’s) was built largely to answer the question of CO2 in the atmosphere (Is it a potential problem?)

    Hansen, J.E., W.-C. Wang, and A.A. Lacis, 1978: Mount Agung eruption provides test of a global climatic perturbation. Science, 199, 1065-1068, doi:10.1126/science.199.4333.1065. Non-paywall pdf courtesy NASA

    The Mount Agung eruption volcanic eruption in 1963 provides the best-documented global radiative perturbation to the earth’s atmosphere currently available. Data on stratospheric aerosols produced by this eruption have been used as input to a model for the atmospheric thermal structure. The computed magnitude, sign, and phase lag of the temperature changes in both the stratosphere and the troposphere are in good agreement with observation, providing evidence that the climatic response to a global radiative perturbation is significant, as well as support for the use of theoretical models to predict climatic effects.

    The Agung eruption was also the subject of Hansen’s Master’s thesis which resulted in a paper in JGR (Hansen, J. E., and S. Matsushima (1966), Light illuminance and color in the Earth’s shadow, J. Geophys. Res., 71(4), 1073–1081, doi:10.1029/JZ071i004p01073.).

  45. Vinny Burgoo says:

    John Hartz, that Newsweek story missed the weirdest way that climate change makes earthquakes worse: meltwater has increased the mass of the oceans so much that they now knead the ocean floor like a baker kneads dough, triggering ever larger earthquakes.

    https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=CRISIS-FORUM;45a6674.1108

    Quite how such a tiny relative change can be producing such enormous effects isn’t explained.

  46. Magma says:

    The melt water build-up massages the elastic properties of the oceanic plates like baker’s roll moves over his dough. Over huge oceanic distances this spread effect becomes significant.

    Your reference is spouting gibberish, Vinny, and you are repeating it.

  47. “And Then There’s Earthquakes…

    The Weird Way That Climate Change Could Make Earthquakes Worse by Kristin Hugo, Newsweek, Sep 24, 2017”

    That’s not exclusively a climate change cause. Building dams/reservoirs and fracking for oil and NG is also related to fossil fuel depletion and the need for energy. We wouldn’t be fracking in Oklahoma and North Dakota if we still had enormous conventional reserves of crude oil and NG. We wouldn’t even be close to considering fracking next to Yellowstone or in the Monterey Formation in California if it wasn’t for how desperate we are for new sources of fossil fuels.

    I do understand why climate change is used as an all-purpose bogeyman — as people can’t grasp more than one issue at a time.

  48. izen says:

    @-Andrew Dodds
    “In a sane world, the climate effects of a major eruption would be seen as nature’s way of giving us more time to get our house in order…”

    That might be unwise.
    The cooling does not ‘stick’, we do not return to warming after a major eruption from that lower level. Volcanic cooling rebounds with equally fast warming after the particulates/SOx falls out of the Atmosphere.

    Major volcanic eruptions are estimated to block about 0.5W/m2 of incoming solar energy. Or about a third as much thermal energy as CO2 blocks exiting the system.
    That causes cooling of the ocean surface for the ~2 years there is volcanic dust in the stratosphere. When that block is removed, the cooler ocean emits less energy so the imbalance is reversed and it warms over a decade or so back to where we would be without the volcanic cooling.
    If this did not happen then volcanic events would historically have ratcheted the surface temperature down to sub-zero.

    I think this is the explanation for the ‘flat’ OHC before 1995 on this graph from the paper I linked before –

    At least I suppose that is why the volcanic events are marked out.

  49. I don’t know about the mass and kneading power of meltwater, but I have wondered about tiny changes in the weight borne by tectonic plates as glaciers melt. Living here on the “ring of fire” and more specifically, on the Cascade suduction zone, I have watched the Fukushima EQ and then the one off Chile, another off Costa Rica, now a couple around Mexico City with some heightened interest. The Cascadia slip zone is somewhere around year 317 with a periodicity of about 241 years. I don’t worry too much about it, but I have done a lot of earthquake bracing and prep work in my 100 year old house anyway and spouse and I have discussed the big one, how we will may get advance notice from barking dogs, how in any case after about 15-30 seconds of shaking we should be out of the house on a hillside and beating feet for what might be a safe zone about 1000 feet away. We have also discussed the 15 minutes between when shaking stops and tsunami arrives at coast. First we dodge the mountainside sliding down, then we watch for tsunami issues I think we are far enough inland that tsunami will not be an issue, but it would be a bad day to be wrong about that. Then we check our emails and internet connection to start checking in with friends. Always good to have a plan because as John Lennon noted, “life is what happens while you are busy making plans.”

  50. angech says:

    I zen
    “The cooling does not ‘stick’, we do not return to warming after a major eruption from that lower level. Volcanic cooling rebounds with equally fast warming after the particulates/SOx falls out of the Atmosphere.”

    The cooling does not stick agreed but we do have to return to warming from that lower level. Furthermore it does not rebound with equally fast warming . There is a sudden and increasing drop in temp due to the sudden outpouring of particulate and its spread then a very slow comparatively return to normal warming as the particulate settles back to the surface in perhaps 10 to 100 years or longer depending on the size of the major eruption (see Yellowstone in past)

  51. The triggering stimulus for earthquakes may not be that large. Several papers within the last year including groups from Japan and the USGS have identified unmistakable pattern correlations between lunisolar phases and earthquake timing and locality.

    [1] Ide, Satoshi, Suguru Yabe, and Yoshiyuki Tanaka. “Earthquake potential revealed by tidal influence on earthquake size-frequency statistics.” Nature Geoscience 9.11 (2016): 834-837.
    [2] van der Elst, Nicholas J., et al. “Fortnightly modulation of San Andreas tremor and low-frequency earthquakes.” Proceedings of the National Academy of Sciences (2016): 201524316.
    [3] Delorey, Andrew A., Nicholas J. van der Elst, and Paul A. Johnson. “Tidal triggering of earthquakes suggests poroelastic behavior on the San Andreas Fault.” Earth and Planetary Science Letters 460 (2017): 164-170.

    The quake trigger is like a mousetrap, if a fault is on the edge of slipping, all it needs is a nudge.

    BTW, this lunisolar mechanism has been percolating for years, with some very convincing yet obscure research papers that long preceded this set. Like this mind-blower :
    Kolvankar, Vinayak G. “Sun, Moon and Earthquakes.” New Concepts in Global Tectonics Newsletter 60 (2011): 50-66.
    https://www.researchgate.net/profile/Vinayak_Kolvankar/publication/262563466_Sun_Moon_and_Earthquakes/links/0c9605380a863463b1000000/Sun-Moon-and-Earthquakes.pdf

  52. Magma says:

    The quake trigger is like a mousetrap, if a fault is on the edge of slipping, all it needs is a nudge.

    That’s a pretty good analogy.

  53. The most sensitive mousetrap is likely the reduced gravity environment of the stratified Pacific ocean thermocline. A hair trigger is all that is required to get the ocean in motion.

    And happy upcoming 100th birthday to Walter Munk, the “Einstein of the Oceans” responsible for this insight !

  54. angech,

    The cooling does not stick agreed but we do have to return to warming from that lower level. Furthermore it does not rebound with equally fast warming .

    The volcanic particles actually precipitate quite quickly. They’ll also be suppressing anthropogenically-driven warming and when they do precipitate we would expect a relatively rapid return to where we would have been if the volcano had not occurred (within years).

  55. angech says:

    I see we have pre emptied WUWT by a day on the significance or not of a volcanic explosion, or not. Personally I hope for the people on Bali it stays dormant.
    Scientifically I hope it does not erupt so the expected fall in global temperature over the next 18 months is not enhanced and contaminated by such an event. Amazing that it takes 30 years of human activity to purportedly creat a 0.15 C rise that a little volcano can snuff out in an instant.

  56. angech,

    the expected fall in global temperature over the next 18 months

    There isn’t really (in the absence of a volcanic eruption) and expected fall in global temperatures over the next 18 months. We have had a number of record warm years, so it is likely that the next few years may not be records, but that’s simply because we don’t expect global temperatures to simply rise year on year, not because we’re really expecting some kind of fall (the system is still accruing energy).

  57. angech says:

    CO2 is increasing year to year so the expectatation is that the temperatures in general should keep simply rising year to year. The probability of this happening is different as we all realise that there is yearly natural variability.
    Hence a number of record warm years in a row is not a reason in this scenario to advocate a pause is due.
    With due respect the fall in ENSO, the increase in Arctic ice and an eyeball decrease in OHC (JCH and others may have the figures to set me to rights here) strongly suggest a prolonged fall in global temp which should last for up to 18 months.

  58. angech,

    CO2 is increasing year to year so the expectatation is that the temperatures in general should keep simply rising year to year.

    Come on, you’ve been involved in this discussing this topic long enough to at least understand this. Increasing atmospheric CO2 acts to reduce the outgoing energy flux, causing energy to accrue in the climate system. Most of this excess energy goes into the oceans, with only a small fraction heating the surface (land/atmosphere). To return to energy balance, it is true that the surface will have to warm, however because such a small fraction heats the surface, it is very sensitive to short-term variability, and – hence – we don’t expect it to warm year-on-year, even if we do expect there to be a long-term warming trend.

  59. regarding angech:

    What you see here is the same thing (to a lesser extent) that afflicts Curry’s blog every morning in America. The Aussie larrikins post the red meat while everyone else is sleeping.

    This creates the delay differential or delayed action oscillator effect that exaggerates the swings in arguments.

  60. Eli Rabett says:

    From reports it looks like Mt. Agung is a cinch to go boom. Any word on how large the explosion is estimated to be?

  61. JCH says:

    CO2 is increasing year to year so the expectatation is that the temperatures in general should keep simply rising year to year.

    Good grief.

    ENSO is not falling. It’s marching right toward doing nothing at all to cause higher and higher temperatures, just as ENSO has down with complete reliability since ACO2 started peeking its cute little smile above the horizon of NV. My personal start year for that is 1952, and my birth year is not a cherry pick. My arrival on the scene is just that important.

  62. Andrew Dodds says:

    Mt Agung’s last big eruption was a VEI 5, the standard test case for climate (in my head, anyway) being a Pinatubo at VEI 6. Latitude matters as well.. El Chichón was a big VEI 5 and the effects were apparently hard to distinguish from the big El nino/la nina that happened around the same time.

    So assuming a rerun of the 1963 eruption, we might not even notice, climatologically-speaking.

  63. “El Chichón was a big VEI 5 and the effects were apparently hard to distinguish from the big El nino/la nina that happened around the same time.”

    But not impossible to distinguish the two. What happened was that El Chichon somewhat cancelled (or compensated) the global temperature rise caused by the 82/83 El Nino. The ENSO index as measured by SOI was not compensated by El Chichon as that is an oceanic effect and immune to atmospheric perturbations. So overall, the two effects could be discriminated to at least some degree, using the SOI as the compensating factor.

  64. Windchaser says:

    Angech:

    CO2 is increasing year to year so the expectatation is that the temperatures in general should keep simply rising year to year.

    If CO2 were the only thing that affected surface temperatures, sure, that would be the case. But we’ve known for a good while that they’re not.

    Amazing that it takes 30 years of human activity to purportedly creat a 0.15 C rise that a little volcano can snuff out in an instant.

    The trend in surface temperatures over the last thirty years is about 0.18 C/decade, so your numbers are off by a factor of 4x here. On average it takes about 8 years to create a 0.15C rise, not 30 years.

    But yeah, a good-sized volcano can snuff that out pretty quickly.. but it also bounces back again once the volcano is quiet.

  65. You are correct about the importance of 1952, but you missed the cause. I have a lot of data that suggests strongly that it was my appearance on the scene that triggered the current era. I keep hearing about the anthropocene and I have not wanted to quibble, but it’s clear to me that we are actually in the michaelopocene. jchopocene? It is as ridiculous as it sounds. Sorry.

  66. Andrew Dodds writes: “So assuming a rerun of the 1963 eruption, we might not even notice, climatologically-speaking.”

    Per the 1978 Hansen,Wang & Lacis paper I referenced earlier I would disagree. They estimated a 0.5°C drop in tropical tropospheric temps at 2 years out (30N-30S) from the 1963 eruption. Even if the effects were limited strictly to the tropics and we only looked at the first 3 or 4 years, the effects were not negligible even in a climatological context.

  67. Andrew – here’s Figure 10 from GLOBAL SURFACE TEMPERATURE CHANGE; J. Hansen,R. Ruedy, M. Sato, & K. Lo; 2010, DOI: 10.1029/2010RG000345

    It’s similar to the figure Izen posted showing the three late 20th century volcanic eruptions on the time axis (1963 Agung, 1982 El Chichon, and 1991 Pinatubo):

  68. izen says:

    @-angtech
    “Furthermore it does not rebound with equally fast warming . There is a sudden and increasing drop in temp due to the sudden outpouring of particulate and its spread then a very slow comparatively return to normal warming as the particulate settles back to the surface in perhaps 10 to 100 years or longer… ”

    The amount of solar dimming, how much energy is blocked and for how long has been directly measured. The rate at which the ocean surface can lose and gain energy is the main time constraint. It is much longer than the dispersion or residence time of volcanic particulates.
    Cooling and warming rates are set by the oceans.

    Because the change in energy balance is reversed with volcanic forcings, (ocean energy flux timescales), the temperature change is neutral. It requires a maintained forcing (centuries?) to maintain a higher temperature because it maintains the energy imbalance until that higher temperature is reached. That is what The extra CO2 in the atmosphere is doing.
    There is a significant, and persistent addition of energy to the system. As indicated by the rising OHC.

    Earthquakes are driven by tectonics, which in turn are driven by convection in the magma. AGW will add no extra energy to that system and I am very dubious it will have much effect on either triggering or inhibiting distribution of major earthquakes.
    By contrast, rising CO2 has introduced extra energy into the climate system. The OHC increase confirms that.
    It seems unlikely that would have less dramatic consequences than its thermodynamically neutral, probably marginal, influence on earthquakes.

  69. Andrew Dodds says:

    oneillsinwisconsin –

    Yes, ‘climatologically-speaking’ was the wrong choice of words.. It’s more that if I look at a climate-related time series, I can usually use 1992 and 1998 as ‘landmarks’ because they have obvious deviations (and if they are not there it makes the time series suspect/surprising), whereas deviations at 1963 or 1981 are not as obvious. Very subjective, I know.

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