Dr. Garth Paltridge on JudithCurry.com: Reluctance of IPCC to reduce confidence levels in light of hiatus and misunderstood mechanisms shows a lack of scientific skepticism. [For fact checking & general commentary]

March 20, 2014 7:18 am15 comments

Summary of initial comments in the Scientists’ Comment Thread [updated 4/28/14]:

Dr. Andreas Schmittner: “G.Paltridge claims that scientists could not exclude the possibility that the surface warming observed over the last 50 years was due to fluctuations in ocean currents. This is extremely unlikely given the observed [changes].  The claim of “no significant warming over the most recent 15-or-so yrs” is also wrong: “[O]cean heat content shows uninterrupted warming… See Global Ocean Heat Content 1955 to present (0-2000m) [here].” 

Dr. Michael Tobis: “Many half-truths and frank misinterpretations here. […] It may or may not be useful to potential audiences to have another place where reason and evidence is placed head to head against posturing and rhetoric. But such a thing is not useful or appealing to scientists.”

Dr. Judith Curry: “G.Paltridge is a distinguished Australian atmospheric physicist. I don’t find much to disagree with in [this] essay. I would hope that other participants who ‘don’t like’ this essay will critique the disputed points and provide evidence refuting his arguments. […]  The uncertainties in ocean heat content below 700 m are very substantial, see here.” 

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The following excerpts are from a recent guest post on JudithCurry.com, titled “The Fundamental Uncertainties of Climate Change,” by Dr. Garth Paltridge. (Click on the link for the full article on JudithCurry.com.)

The Fundamental Uncertainties of Climate Change, by Garth Paltridge

There is more than enough uncertainty about the forecasting of climate to allow normal human beings to be at least reasonably hopeful that global warming might not be nearly as bad as is currently touted.  Climate scientists, and indeed scientists in general, are not so lucky.  They have a lot to lose if time should prove them wrong.

Dr. Garth Paltridge

Dr. Garth Paltridge. Source: YouTube

The World Meteorological Organization of the United Nations took its first steps towards establishing the World Climate Program in the early nineteen-seventies.  Among other things it held an international conference in Stockholm to define the main scientific problems to be solved before reliable climate forecasting could be possible.  The conference […] focused on two [problems].  The first concerned an inability to simulate the amount and character of clouds in the atmosphere.  Clouds are important because they govern the balance between solar heating and infrared cooling of the planet, and thereby are a control of Earth’s temperature.  The second concerned an inability to forecast the behavior of oceans.  Oceans are important because they are the main reservoirs of heat in the climate system.  They have internal, more-or-less random, fluctuations on all sorts of time-scales ranging from years through to centuries.  These fluctuations cause changes in ocean surface temperature that in turn affect Earth’s overall climate.

The situation hasn’t changed all that much in the decades since the conference.  Many of the problems of simulating the behavior of clouds and oceans are still there (along with lots of other problems of lesser moment) and for many of the same reasons as were appreciated at the time. Perhaps the most significant is that climate models must do their calculations at each point of an imaginary grid of points spread evenly around the world at various heights in the atmosphere and depths in the ocean.  The calculations are done every hour or so of model time as the model steps forward into its theoretical future.   Problems arise because practical constraints on the size of computers ensure that the horizontal distance between model grid-points may be as much as a degree or two of latitude or longitude – that is to say, a distance of many tens of kilometres.

That sort of distance is much larger than the size of a typical piece of cloud.   As a consequence, simulation of clouds requires a fair amount of inspired guesswork as to what might be a suitable average of whatever is going on between the grid-points of the model.  Even if experimental observations suggest that the models get the averages roughly right for a short-term forecast, there is no guarantee they will get them right for atmospheric conditions several decades into the future.  Among other problems, small errors in the numerical modelling of complex processes have a nasty habit of accumulating with time.

Again because of this grid-point business, oceanic fluctuations and eddies smaller than the distance between the grid-points of a model are unknown to that model.  This would not be a problem except that eddies in turbulent fluids can grow larger and larger.  A small random eddy in the real ocean can grow and appear out of nowhere as far as a forecasting model is concerned, and make something of a dog’s breakfast of the forecast from that time on.

All of the above is background to one of the great mysteries of the climate change issue.  Virtually all the scientists directly involved in climate prediction are aware of the enormous problems and uncertainties still associated with their product.  How then is it that those of them involved in the latest report of the Intergovernmental Panel on Climate Change (the IPCC) can put their hands on their hearts and maintain there is a 95% probability that human emissions of carbon dioxide have caused most of the global warming that has occurred over the last several decades?

"A graph that makes a mockery of warming"

A graph recently published by the Daily Mail (UK) and allegedly based on a graph published by Dr. Ed Hawkings of Reading University (republished here by Michael Quirke).

Global Annual Mean Surface Air Temperature Change. Credit: NASA Goddard Insitute for Space Studies

Graph showing global annual mean surface air temperature change from 1880-2013. Credit: NASA Goddard Institute for Space Studies (republished here by Michael Quirke).

Bear in mind that the representation of clouds in climate models (and of the water vapour which is intimately involved with cloud formation) is such as to amplify the forecast warming from increasing atmospheric carbon dioxide – on average over most of the models by a factor of about 3.   In other words, two-thirds of the forecast rise in temperature derives from this particular model characteristic.   Despite what the models are telling us – and perhaps because it is models that are telling us – no scientist close to the problem and in his right mind, when asked the specific question, would say that he is 95% sure that the effect of clouds is to amplify rather than to reduce the warming effect of increasing carbon dioxide.  If he is not sure that clouds amplify global warming, he cannot be sure that most of the global warming is a result of increasing carbon dioxide.

Bear in mind too that no scientist close to the problem and in his right mind, when asked the specific question, would say there is only a very small possibility (i.e. less than 5%) that internal ocean behaviour could be a major cause of the warming over the past half-century.  He would be particularly careful not to make such a statement now that there has been no significant warming over the most recent fifteen-or-so years.  In the mad scurry to find reasons for the pause, and to find reasons for an obvious failure of the models to simulate the pause, suddenly we are hearing that perhaps the heat of global warming is being “hidden” in the deep ocean.  In other words we are being told that some internal oceanic fluctuation may have reduced the upward trend in global temperature.  It is therefore more than a little strange that we are not hearing from the IPCC (or at any rate not hearing very loudly) that some natural internal fluctuation of the system may have given rise to most of the earlier upward trend.

"The Climate Caper," a book by Dr. Garth Paltridge with a foreword by Lord Christopher Monckton

“The Climate Caper,” a 2010 book by Dr. Garth Paltridge with a foreword by Lord Christopher Monkton.

In the light of all this, we have at least to consider the possibility that the scientific establishment behind the global warming issue has been drawn into the trap of seriously overstating the climate problem – or, what is much the same thing, of seriously understating the uncertainties associated with the climate problem – in its effort to promote the cause.   It is a particularly nasty trap in the context of science, because it risks destroying, perhaps for centuries to come, the unique and hard-won reputation for honesty which is the basis of society’s respect for scientific endeavour.  Trading reputational capital for short-term political gain isn’t the most sensible way of going about things.

The trap was set in the late seventies or thereabouts when the environmental movement first realised that doing something about global warming would play to quite a number of its social agendas.   At much the same time, it became accepted wisdom around the corridors of power that government-funded scientists (i.e. most scientists) should be required to obtain a goodly fraction of their funds and salaries from external sources – external anyway to their own particular organization.

[…]

The trap was fully sprung when many of the world’s major national academies of science (the Royal Society in the UK, the National Academy of Sciences in the US, the Australian Academy of Science, and so on) persuaded themselves to issue reports giving support to the conclusions of the IPCC.  The reports were touted as national assessments that were supposedly independent of the IPCC and of each other, but of necessity were compiled with the assistance of, and in some cases at the behest of, many of the scientists involved in the IPCC international machinations.   In effect, the academies, which are the most prestigious of the institutions of science, formally nailed their colours to the mast of the politically correct.

Since that time in 2010-11 or thereabouts, there has been no comfortable way for the scientific community to raise the spectre of serious uncertainty about the forecasts of climatic disaster.

[…]

What has happened to the scepticism that is supposedly the lifeblood of scientific enquiry?

The answer probably gets back to the uncertainty of it all.  The chances of proving – repeat proving – that change of climate over the next century will be large enough to be disastrous are virtually nil.  For the same reason, the chances of a climate sceptic, or anyone else for that matter, proving the disaster theory to be oversold are also virtually nil.  To that extent there is a level playing field for the two sides of the argument.  The problem is that climate research necessarily involves enormous resources, and is a game for institutions and organizations.  Scepticism is an occupation for individuals.  Things being as they are in the climate change arena, scepticism by an individual within the system can be fairly career limiting.  In any event, most individual scientists have a conscience, and are reluctant to put their head above the public parapet in order to propound a view of things that may be inherently unprovable.

In short, there is more than enough uncertainty about the forecasting of climate to allow normal human beings to be at least reasonably hopeful that global warming might not be nearly as bad as is currently touted.  Climate scientists, and indeed scientists in general, are not so lucky.  They have a lot to lose if time should prove them wrong.

Dr. Garth Paltridge is a retired atmospheric physicist from Australia. He is an emeritus professor and honorary research fellow at the University of Tasmania, visiting fellow at the Australian National University Research School of Biology, and fellow of the Australian Academy of Science. The full transcript of this post can be found at JudithCurry.com (click on link). This piece was originally published in Quadrant magazineJan-Feb 2014, and is accessible via Quadrant On Line.

Administrator’s note: The summary of the initial comments by the CCNF scientists at the top was added to this post on 4/28/14. This is the new format for the ‘Climate Change in the Media — Commentary and fact checking…’ section. 

THE FORUM'S COMMENT THREAD

  • G.Paltridge claims that scientists could not exclude the possibility that the surface warming observed over the last 50 years was due to fluctuations in ocean currents. This is extremely unlikely given the observed heat content changes in the oceans. The figure below shows the oceans heat content change from 1955 to 2010 as a function of depth. It is clear that the ocean is warming from the top down because that’s where the warming is strongest. There is no evidence that the surface warming may come from somewhere in the deep ocean since this would require the deep layers to cool. Note that there is no cooling anywhere. Could the ocean below 2000 m have cooled? This figure cannot answer that question but I think there is no evidence for that either. The figure is from Levitus et al. (2012) available here.

    One more point on Paltridge’s essay. He writes “now that there has been no significant warming over the most recent fifteen-or-so years”. This statement is wrong (or misleading at best) because the ocean heat content shows uninterrupted warming. Because 90% or so of all heat goes into the ocean, this is the place to look for warming. See Global Ocean Heat Content 1955 to present (0-2000m).

    Paltridge conveniently neglects these observations because the don’t fit into his attempt to sow doubt on the scientific consensus on climate change as expressed by the IPCC and the academies of science. However, he accuses climate scientists of dishonesty, which is shameful, but I have seen similar allegations from climate skeptics earlier. For lack of scientific arguments they attack climate scientists’ integrity.

  • Michael, the resistance you are seeing here is the tip of the iceberg.

    I have been trying to convince scientists that this site presents a level playing field where the true balance of science can emerge, and I’ve been rebuffed with the idea that this site is another example of “false balance”, wherein the politically structured arguments will again take precedence. That argument is being bolstered by this article, and indeed the attention to this article is a direct result of my trying to convince people who might participate that this

    Many half-truths and frank misinterpretations are here. The scientific community is not lacking for opportunity to address these, and another site where such things appear does not appeal to them.

    I would think the objective of CCNF is to address issues that are scientifically cogent, not those that are merely politically viable.

    It is not appealing for practicing scientists to have yet another place to address the latter, and the essentially bottomless job of rebutting such ill-founded arguments should not fall to the small population of professional scientists whose time and attention are limited.

    It may or may not be useful to potential audiences to have another place where reason and evidence is placed head to head against posturing and rhetoric. But such a thing is not useful or appealing to scientists.

    If you want to know what scientists are thinking, don’t drive the conversation by what misinformation is prominent among nonscientists.

  • Dr. Tobis: This is a fact checker section. Perhaps we should name it “Climate Change in the Media — Outside material posted for fact checking and commentary by the CCNF Scientist Community”? (That’s a little long, but it would make it more explicit.)

    In this section, I purposefully give attention to the full gamut of coverage on climate science by the media: this includes the good, the bad, and the ugly. I leave it to the scientists to say which is which.

    The purpose of giving space to what you and other scientists determine to be “half-truths” and “misinterpretations” in this section becomes apparent when you search for the content in Google. I cleared my browser history and tried searching for “Dr. Garth Paltridge” just now. CCNF’s post comes up first. This is a powerful accountability mechanism in the online space, but not if the journalist only posts what he believes to be “scientifically cogent” material.

    If you think something is nothing more than politically viable junk, it is important that you say so and say why. That does a world of service to our readers and the readers that will stumble across the article in a Google search.

    I recognize that identifying and rebutting “ill-founded arguments” in the media is an endless job and might elicit some eye rolls from the scientists, which is why I try to limit posting what I consider to be junk. In our last conference call, many of the scientists mentioned that they do not want baseless claims and outrageous articles to drive the conversation. That being said, those same scientists did recognize the importance of posting such material every in order to subject it to the scrutiny of the scientists in the Scientists’ Comment Thread.

    There’s a lot of misinformation and disinformation out there. Would it be of service to completely ignore this? As for what the perfect balance is in identifying and exposing misinformation on one hand but not giving it so much attention that it drives the conversation and gives the appearance of a false balance on the other, I am all ears.

    Very Respectfully,

    Michael

  • Garth Paltridge is a distinguished Australian atmospheric physicist. I don’t find much to disagree with in Paltridge’s essay. I would hope that the other participants who ‘don’t like’ this essay will critique the disputed points and provide evidence refuting Paltridge’s arguments. There is sufficient uncertainty in all this to support different perspectives, and I thank CNNF for highlighting Paltridge’s perspective.

    The uncertainties in ocean heat content below 700 m are very substantial, see
    http://judithcurry.com/2014/01/21/ocean-heat-content-uncertainties/

  • Judith: do you agree to his statement that “no scientist close to the problem and in his right mind … would say there is only a very small possibility (i.e. less than 5%) that internal ocean behaviour could be a major cause of the warming over the past half-century.” ?

    • Well, I would say this statement is about as sensible about the highly touted statements about 97% of scientists agreeing. If you clarify ‘scientist close to the problem’ to mean scientists with expertise in ocean dynamics’, Paltridge could be right, I don’t know — a good question for a future survey, but then you need to define ‘major’ for clarity.

      • Sorry Judith, but I know quite a lot of oceanographers who I’m sure do not think that internal ocean behavior was a major cause of the warming of the last 50 years. If you find anything to object to my argument made above, please let me know. Here http://climatechangenationalforum.org/deep-ocean-warming/ is a little more discussion of this point with a figure of deep ocean warming.

        So please let me know if you question my expertise or my state of mind (and those of my many colleagues who).

        • Well this is rather pointless. I also know a lot of oceanographers, who agree with Paltridge. Appeals to authority are pointless as far as I’m concerned. I have written a number of blog posts regarding multidecadal variability in the ocean and the uncertainties in ocean heat content data below 700 m prior to about 2004. My arguments are clearly laid out for all to consider.

          I know nothing of your state of mind and almost as little about your expertise. I pay attention to serious arguments, and I haven’t really seen one from you yet on this thread.

          • I don’t think it is pointless. THe point is that you don’t disagree with Paltridge’s abusive ad hominem. You even come up with your own by falsely stating that I haven’t provided serious arguments. This conversation is over!

  • Scientists can reasonably argue many different things, since the system is complex, and data is incomplete and ambiguous.

    The role of internal ocean behavior in climate change was almost completely neglected up the AR4; the AR5 takes it a bit more seriously. But recent research over the past year has resulted in this being a huge issue. Everyone seems to be jumping on the bandwagon to say that internal ocean variability is causing the pause, but this leads to questions about the role of oceans in the warming of the last quarter of the 20th century

  • Judith: you don’t answer my question. I was asking if you agree with him.

  • Well, this has all become rather circular. Andreas posts a new article that features the same graph that Judith criticizes at her own blog in the post she refers to above in her April 21 comment.

    Let’s see if I can sort this out. Andreas argues that for the source of surface warming to have been primarily internal to the system (i.e. natural variability), there would need to be a compensating loss of heat from the deeper ocean. This makes physical sense to me.

    Judith doesn’t dispute this. Instead she points to her earlier discussions where she notes that there is considerable uncertainty in ocean heat content, especially decades ago.

    In her Climate Etc. post of January 21, she compares six figures: 0-700m OHC (from AR4), 0-700m OHC (from AR5), 0-various depths OHC (from Lyman and Johnson), 700-2000m and 2000-6000m OHC (from AR5), 0-various depths OHC (from Balmaseda et al.), and sea level The subject of the post is primarily ocean heat variations over the past 17 years, with Judith arguing that Balmaseda et al. in particular is inconsistent with the others.

    Though the main focus is not on the past 50 years, we can see from her graphs that none of the analyses she discusses have a decline in OHC over the past 50 years, neither in their best estimate nor within their error bounds. Likewise, sea level continues to rise, with a major component being thermal expansion, as Judith notes in the same entry.

    From this I conclude that there is no evidential support for the idea that OHC declined over the past 50 years, and indeed all of the evidence points toward an increase of OHC. Therefore the idea that the increase in global surface temperature over that same interval was caused by natural heat transfer from the ocean is likewise unsupportable.

    In passing, I wish to point out a couple of statements in Judith’s blog entry that seem incorrect.

    First, she says “The most surprising thing about the Balmaseda analysis is that the warming increases with increasing depth (largest warming for the 0-7000 m layer).” But all available analyses show that almost all levels of the ocean are warming, so the deeper the layer you analyze, the greater the amount of energy storage you’ll find. There’s nothing surprising about that unless the energy increase per unit depth is larger in the lower ocean than in the upper ocean. Since 2000, according to Balmaseda et al., the upper 700 m gained 9×10^22 J, while the total depth gained 13×10^22 J. That means that most of the heat went into the upper 700 m. Since 2004, the numbers are 1.5×10^22 and 4×10^22, and since the average depth of the ocean is about 4000 m, the heat gain continues to be most strongly concentrated in the upper ocean.

    Second, with regard to sea level rise, Judith says, “…the thermal expansion was more dominant in [the 1930s-1950s]. Which suggests that ocean heat content was greater in this early period than in the current period, and cannot be attributed to AGW.” A minor point is that only one of the three sea level rise analyses clearly supports the thermal expansion being larger in the earlier period. More importantly, this would imply not that ocean heat content was greater in the earlier period, but that the RATE OF CHANGE of ocean heat content was greater in the earlier period. On balance, considering all three sea level rise analyses, the rate of change of ocean heat content might have been similar then as now. One could argue from this that some of the ocean heat content rise might have been due to natural variability, but it certainly doesn’t imply that AGW had zero effect in either period.

    • A reader who wishes to remain anonymous has emailed me to challenge Andreas’s assumption that natural variability causing rising surface temperatures would be accompanied by a decline in ocean heat content. I’m posting his comment beneath Andreas’s post, because that’s where the issue was first raised.

  • Judith Curry says: “I would hope that the other participants who ‘don’t like’ this essay will critique the disputed points and provide evidence refuting Paltridge’s arguments.” Indeed, the readers deserve as much. Now that my semester of teaching is over, I’ll try doing this systematically.

    I’ll start with paragraph #4. Palgridge says: “That sort of distance is much larger than the size of a typical piece of cloud. As a consequence, simulation of clouds requires a fair amount of inspired guesswork as to what might be a suitable average of whatever is going on between the grid-points of the model.”

    Mostly true. The task of estimating what’s happening on a scale smaller than a climate model can simulate directly is called “parameterization”. Clouds are one of the key parameterizations in climate models. The task is to infer what’s happening on a small scale, given the larger-scale conditions that the model is simulating. Clouds, for example, are inferred to be present if the average relative humidity over the grid box exceeds a certain value. The higher the humidity, the greater the inferred amount of cloud cover. I wouldn’t call this task “inspired guesswork”, though, because it’s based on actual observed relationships between large-scale conditions and the smaller-scale processes of interest. “Guesswork” implies that observations don’t play the critical role that they do.

    Continuing, Paltridge says: “Even if experimental observations suggest that the models get the averages roughly right for a short-term forecast, there is no guarantee they will get them right for atmospheric conditions several decades into the future.”

    Truthy rather than true. Precisely because there is no such guarantee, the model simulations of climate are run for many decades. This gives the model ample time to “forget” its initial conditions and settle on a simulated global climate state that’s quite independent of whatever it started with. Then, only after the model simulation has lost all vestige of skill that might have arisen artificially by starting from a realistic initial state, the climate simulation from the model is compared to the observed climate. Many key aspects are compared against observations, such as the patterns of temperature, rainfall, wind, pressure, and so forth. The extent to which the model’s simulated climate agrees with our observations of the real climate system are then analyzed and reported. You don’t need a guarantee of model performance when you have the actual performance numbers available.

    Then Paltridge says: “Among other problems, small errors in the numerical modelling of complex processes have a nasty habit of accumulating with time.”

    Very truthy. This is why weather forecasts are inaccurate beyond a week or so. But climate simulations aren’t trying to simulate the current state of the atmosphere, they’re trying to simulate the statistics of the atmosphere: average conditions, variability, seasonality, and so forth. It doesn’t matter how rapidly errors accrue for weather, the models ALWAYS correctly simulate that summer is warmer than winter, for example.

    If the climate variable of interest is global surface temperature, and the climate forcing is held constant, there are two possibilities: either a climate model will simulate a statistically stationary climate with natural variability producing quasi-random variations about a steady average climate state, or a climate model will simulate an unsteady climate that wanders irregularly across the decades and centuries. It turns out that almost all climate models simulate a stationary climate.

    In summary, Paltridge’s criticisms of climate models in paragraph 4 are belied by the actual output and testing of those very same models.

  • [UPDATE 7/7/2014 — Issue is fixed! “CCNF 2.0″ IS NOW FULLY OPERATIONAL!!]

    Administrator’s note : Comments from the Public Comment Thread have been displaying in the Scientists’ Comment Thread and ‘Recent Comments’ sidebar widget these past few days. This is the one glitch that has manifested itself since the transition to “CCNF 2.0″ last week. Working on fixing this now. Will make sure to not lose the last three comments from the public.

    Also, will just add that we at CCNF greatly appreciate comments from our readers and pride ourselves on facilitating communication between the climate and physical scientist community and members of the public. If you decide to participate in this national dialogue, and we hope you do, please politely identify yourself. The participating scientists are demonstrating a special courage and generosity by giving their time and energy to publicly engage with one another and with members of the public on this issue, so I think it is only fair for folks to identify themselves with a first and last name signature if not username. Otherwise, one is left wondering who he or she is talking to. Our previous Facebook plug-in for the Public Comment Thread required this in effect. I think it is a precedent worth continuing. Anonymity often can often lead to an unnecessarily acrimonious discussion in any chat room. Plus, we often have journalists and other scientists chiming in in the Public Comment Thread.

    -MQ

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PUBLIC COMMENT THREAD

  • http://ceoas.oregonstate.edu/profile/schmittner/ Andreas Schmittner

    G.Paltridge claims that scientists could not exclude the possibility that the surface warming observed over the last 50 years was due to fluctuations in ocean currents. This is extremely unlikely given the observed heat content changes in the oceans. The figure below shows the oceans heat content change from 1955 to 2010 as a function of depth. It is clear that the ocean is warming from the top down because that’s where the warming is strongest. There is no evidence that the surface warming may come from somewhere in the deep ocean since this would require the deep layers to cool. Note that there is no cooling anywhere. Could the ocean below 2000 m have cooled? This figure cannot answer that question but I think there is no evidence for that either. The figure is from Levitus et al. (2012) available here.

    One more point on Paltridge’s essay. He writes “now that there has been no significant warming over the most recent fifteen-or-so years”. This statement is wrong (or misleading at best) because the ocean heat content shows uninterrupted warming. Because 90% or so of all heat goes into the ocean, this is the place to look for warming. See Global Ocean Heat Content 1955 to present (0-2000m).

    Paltridge conveniently neglects these observations because the don’t fit into his attempt to sow doubt on the scientific consensus on climate change as expressed by the IPCC and the academies of science. However, he accuses climate scientists of dishonesty, which is shameful, but I have seen similar allegations from climate skeptics earlier. For lack of scientific arguments they attack climate scientists’ integrity.

  • http://planet3.org/ Michael Tobis

    Michael, the resistance you are seeing here is the tip of the iceberg.

    I have been trying to convince scientists that this site presents a level playing field where the true balance of science can emerge, and I’ve been rebuffed with the idea that this site is another example of “false balance”, wherein the politically structured arguments will again take precedence. That argument is being bolstered by this article, and indeed the attention to this article is a direct result of my trying to convince people who might participate that this

    Many half-truths and frank misinterpretations are here. The scientific community is not lacking for opportunity to address these, and another site where such things appear does not appeal to them.

    I would think the objective of CCNF is to address issues that are scientifically cogent, not those that are merely politically viable.

    It is not appealing for practicing scientists to have yet another place to address the latter, and the essentially bottomless job of rebutting such ill-founded arguments should not fall to the small population of professional scientists whose time and attention are limited.

    It may or may not be useful to potential audiences to have another place where reason and evidence is placed head to head against posturing and rhetoric. But such a thing is not useful or appealing to scientists.

    If you want to know what scientists are thinking, don’t drive the conversation by what misinformation is prominent among nonscientists.

  • http://ClimateChangeNationalForum.org Michael Quirke

    Dr. Tobis: This is a fact checker section. Perhaps we should name it “Climate Change in the Media — Outside material posted for fact checking and commentary by the CCNF Scientist Community”? (That’s a little long, but it would make it more explicit.)

    In this section, I purposefully give attention to the full gamut of coverage on climate science by the media: this includes the good, the bad, and the ugly. I leave it to the scientists to say which is which.

    The purpose of giving space to what you and other scientists determine to be “half-truths” and “misinterpretations” in this section becomes apparent when you search for the content in Google. I cleared my browser history and tried searching for “Dr. Garth Paltridge” just now. CCNF’s post comes up first. This is a powerful accountability mechanism in the online space, but not if the journalist only posts what he believes to be “scientifically cogent” material.

    If you think something is nothing more than politically viable junk, it is important that you say so and say why. That does a world of service to our readers and the readers that will stumble across the article in a Google search.

    I recognize that identifying and rebutting “ill-founded arguments” in the media is an endless job and might elicit some eye rolls from the scientists, which is why I try to limit posting what I consider to be junk. In our last conference call, many of the scientists mentioned that they do not want baseless claims and outrageous articles to drive the conversation. That being said, those same scientists did recognize the importance of posting such material every in order to subject it to the scrutiny of the scientists in the Scientists’ Comment Thread.

    There’s a lot of misinformation and disinformation out there. Would it be of service to completely ignore this? As for what the perfect balance is in identifying and exposing misinformation on one hand but not giving it so much attention that it drives the conversation and gives the appearance of a false balance on the other, I am all ears.

    Very Respectfully,

    Michael

  • http://judithcurry.com/ Judith Curry

    Garth Paltridge is a distinguished Australian atmospheric physicist. I don’t find much to disagree with in Paltridge’s essay. I would hope that the other participants who ‘don’t like’ this essay will critique the disputed points and provide evidence refuting Paltridge’s arguments. There is sufficient uncertainty in all this to support different perspectives, and I thank CNNF for highlighting Paltridge’s perspective.

    The uncertainties in ocean heat content below 700 m are very substantial, see
    http://judithcurry.com/2014/01/21/ocean-heat-content-uncertainties/

  • http://ceoas.oregonstate.edu/profile/schmittner/ Andreas Schmittner

    Judith: do you agree to his statement that “no scientist close to the problem and in his right mind … would say there is only a very small possibility (i.e. less than 5%) that internal ocean behaviour could be a major cause of the warming over the past half-century.” ?

    • http://judithcurry.com/ Judith Curry

      Well, I would say this statement is about as sensible about the highly touted statements about 97% of scientists agreeing. If you clarify ‘scientist close to the problem’ to mean scientists with expertise in ocean dynamics’, Paltridge could be right, I don’t know — a good question for a future survey, but then you need to define ‘major’ for clarity.

      • http://ceoas.oregonstate.edu/profile/schmittner/ Andreas Schmittner

        Sorry Judith, but I know quite a lot of oceanographers who I’m sure do not think that internal ocean behavior was a major cause of the warming of the last 50 years. If you find anything to object to my argument made above, please let me know. Here http://climatechangenationalforum.org/deep-ocean-warming/ is a little more discussion of this point with a figure of deep ocean warming.

        So please let me know if you question my expertise or my state of mind (and those of my many colleagues who).

        • http://judithcurry.com/ Judith Curry

          Well this is rather pointless. I also know a lot of oceanographers, who agree with Paltridge. Appeals to authority are pointless as far as I’m concerned. I have written a number of blog posts regarding multidecadal variability in the ocean and the uncertainties in ocean heat content data below 700 m prior to about 2004. My arguments are clearly laid out for all to consider.

          I know nothing of your state of mind and almost as little about your expertise. I pay attention to serious arguments, and I haven’t really seen one from you yet on this thread.

          • http://ceoas.oregonstate.edu/profile/schmittner/ Andreas Schmittner

            I don’t think it is pointless. THe point is that you don’t disagree with Paltridge’s abusive ad hominem. You even come up with your own by falsely stating that I haven’t provided serious arguments. This conversation is over!

  • http://judithcurry.com/ Judith Curry

    Scientists can reasonably argue many different things, since the system is complex, and data is incomplete and ambiguous.

    The role of internal ocean behavior in climate change was almost completely neglected up the AR4; the AR5 takes it a bit more seriously. But recent research over the past year has resulted in this being a huge issue. Everyone seems to be jumping on the bandwagon to say that internal ocean variability is causing the pause, but this leads to questions about the role of oceans in the warming of the last quarter of the 20th century

  • http://ceoas.oregonstate.edu/profile/schmittner/ Andreas Schmittner

    Judith: you don’t answer my question. I was asking if you agree with him.

  • http://atmo.tamu.edu/profile/JNielsen-Gammon John Nielsen-Gammon

    Well, this has all become rather circular. Andreas posts a new article that features the same graph that Judith criticizes at her own blog in the post she refers to above in her April 21 comment.

    Let’s see if I can sort this out. Andreas argues that for the source of surface warming to have been primarily internal to the system (i.e. natural variability), there would need to be a compensating loss of heat from the deeper ocean. This makes physical sense to me.

    Judith doesn’t dispute this. Instead she points to her earlier discussions where she notes that there is considerable uncertainty in ocean heat content, especially decades ago.

    In her Climate Etc. post of January 21, she compares six figures: 0-700m OHC (from AR4), 0-700m OHC (from AR5), 0-various depths OHC (from Lyman and Johnson), 700-2000m and 2000-6000m OHC (from AR5), 0-various depths OHC (from Balmaseda et al.), and sea level The subject of the post is primarily ocean heat variations over the past 17 years, with Judith arguing that Balmaseda et al. in particular is inconsistent with the others.

    Though the main focus is not on the past 50 years, we can see from her graphs that none of the analyses she discusses have a decline in OHC over the past 50 years, neither in their best estimate nor within their error bounds. Likewise, sea level continues to rise, with a major component being thermal expansion, as Judith notes in the same entry.

    From this I conclude that there is no evidential support for the idea that OHC declined over the past 50 years, and indeed all of the evidence points toward an increase of OHC. Therefore the idea that the increase in global surface temperature over that same interval was caused by natural heat transfer from the ocean is likewise unsupportable.

    In passing, I wish to point out a couple of statements in Judith’s blog entry that seem incorrect.

    First, she says “The most surprising thing about the Balmaseda analysis is that the warming increases with increasing depth (largest warming for the 0-7000 m layer).” But all available analyses show that almost all levels of the ocean are warming, so the deeper the layer you analyze, the greater the amount of energy storage you’ll find. There’s nothing surprising about that unless the energy increase per unit depth is larger in the lower ocean than in the upper ocean. Since 2000, according to Balmaseda et al., the upper 700 m gained 9×10^22 J, while the total depth gained 13×10^22 J. That means that most of the heat went into the upper 700 m. Since 2004, the numbers are 1.5×10^22 and 4×10^22, and since the average depth of the ocean is about 4000 m, the heat gain continues to be most strongly concentrated in the upper ocean.

    Second, with regard to sea level rise, Judith says, “…the thermal expansion was more dominant in [the 1930s-1950s]. Which suggests that ocean heat content was greater in this early period than in the current period, and cannot be attributed to AGW.” A minor point is that only one of the three sea level rise analyses clearly supports the thermal expansion being larger in the earlier period. More importantly, this would imply not that ocean heat content was greater in the earlier period, but that the RATE OF CHANGE of ocean heat content was greater in the earlier period. On balance, considering all three sea level rise analyses, the rate of change of ocean heat content might have been similar then as now. One could argue from this that some of the ocean heat content rise might have been due to natural variability, but it certainly doesn’t imply that AGW had zero effect in either period.

    • http://atmo.tamu.edu/profile/JNielsen-Gammon John Nielsen-Gammon

      A reader who wishes to remain anonymous has emailed me to challenge Andreas’s assumption that natural variability causing rising surface temperatures would be accompanied by a decline in ocean heat content. I’m posting his comment beneath Andreas’s post, because that’s where the issue was first raised.

  • http://atmo.tamu.edu/profile/JNielsen-Gammon John Nielsen-Gammon

    Judith Curry says: “I would hope that the other participants who ‘don’t like’ this essay will critique the disputed points and provide evidence refuting Paltridge’s arguments.” Indeed, the readers deserve as much. Now that my semester of teaching is over, I’ll try doing this systematically.

    I’ll start with paragraph #4. Palgridge says: “That sort of distance is much larger than the size of a typical piece of cloud. As a consequence, simulation of clouds requires a fair amount of inspired guesswork as to what might be a suitable average of whatever is going on between the grid-points of the model.”

    Mostly true. The task of estimating what’s happening on a scale smaller than a climate model can simulate directly is called “parameterization”. Clouds are one of the key parameterizations in climate models. The task is to infer what’s happening on a small scale, given the larger-scale conditions that the model is simulating. Clouds, for example, are inferred to be present if the average relative humidity over the grid box exceeds a certain value. The higher the humidity, the greater the inferred amount of cloud cover. I wouldn’t call this task “inspired guesswork”, though, because it’s based on actual observed relationships between large-scale conditions and the smaller-scale processes of interest. “Guesswork” implies that observations don’t play the critical role that they do.

    Continuing, Paltridge says: “Even if experimental observations suggest that the models get the averages roughly right for a short-term forecast, there is no guarantee they will get them right for atmospheric conditions several decades into the future.”

    Truthy rather than true. Precisely because there is no such guarantee, the model simulations of climate are run for many decades. This gives the model ample time to “forget” its initial conditions and settle on a simulated global climate state that’s quite independent of whatever it started with. Then, only after the model simulation has lost all vestige of skill that might have arisen artificially by starting from a realistic initial state, the climate simulation from the model is compared to the observed climate. Many key aspects are compared against observations, such as the patterns of temperature, rainfall, wind, pressure, and so forth. The extent to which the model’s simulated climate agrees with our observations of the real climate system are then analyzed and reported. You don’t need a guarantee of model performance when you have the actual performance numbers available.

    Then Paltridge says: “Among other problems, small errors in the numerical modelling of complex processes have a nasty habit of accumulating with time.”

    Very truthy. This is why weather forecasts are inaccurate beyond a week or so. But climate simulations aren’t trying to simulate the current state of the atmosphere, they’re trying to simulate the statistics of the atmosphere: average conditions, variability, seasonality, and so forth. It doesn’t matter how rapidly errors accrue for weather, the models ALWAYS correctly simulate that summer is warmer than winter, for example.

    If the climate variable of interest is global surface temperature, and the climate forcing is held constant, there are two possibilities: either a climate model will simulate a statistically stationary climate with natural variability producing quasi-random variations about a steady average climate state, or a climate model will simulate an unsteady climate that wanders irregularly across the decades and centuries. It turns out that almost all climate models simulate a stationary climate.

    In summary, Paltridge’s criticisms of climate models in paragraph 4 are belied by the actual output and testing of those very same models.

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  • http://ClimateChangeNationalForum.org Michael Quirke

    [UPDATE 7/7/2014 — Issue is fixed! “CCNF 2.0″ IS NOW FULLY OPERATIONAL!!]

    Administrator’s note : Comments from the Public Comment Thread have been displaying in the Scientists’ Comment Thread and ‘Recent Comments’ sidebar widget these past few days. This is the one glitch that has manifested itself since the transition to “CCNF 2.0″ last week. Working on fixing this now. Will make sure to not lose the last three comments from the public.

    Also, will just add that we at CCNF greatly appreciate comments from our readers and pride ourselves on facilitating communication between the climate and physical scientist community and members of the public. If you decide to participate in this national dialogue, and we hope you do, please politely identify yourself. The participating scientists are demonstrating a special courage and generosity by giving their time and energy to publicly engage with one another and with members of the public on this issue, so I think it is only fair for folks to identify themselves with a first and last name signature if not username. Otherwise, one is left wondering who he or she is talking to. Our previous Facebook plug-in for the Public Comment Thread required this in effect. I think it is a precedent worth continuing. Anonymity often can often lead to an unnecessarily acrimonious discussion in any chat room. Plus, we often have journalists and other scientists chiming in in the Public Comment Thread.

    -MQ

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