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Back to the future

Filed under: — gavin @ 30 April 2008 - (Español)

A few weeks ago I was at a meeting in Cambridge that discussed how (or whether) paleo-climate information can reduce the known uncertainties in future climate simulations.

The uncertainties in the impacts of rising greenhouse gases on multiple systems are significant: the potential impact on ENSO or the overturning circulation in the North Atlantic, probable feedbacks on atmospheric composition (CO2, CH4, N2O, aerosols), the predictability of decadal climate change, global climate sensitivity itself, and perhaps most importantly, what will happen to ice sheets and regional rainfall in a warming climate.

The reason why paleo-climate information may be key in these cases is because all of these climate components have changed in the past. If we can understand why and how those changes occurred then, that might inform our projections of changes in the future. Unfortunately, the simplest use of the record – just going back to a point that had similar conditions to what we expect for the future – doesn’t work very well because there are no good analogs for the perturbations we are making. The world has never before seen such a rapid rise in greenhouse gases with the present-day configuration of the continents and with large amounts of polar ice. So more sophisticated approaches must be developed and this meeting was devoted to examining them.

The first point that can be made is a simple one. If something happened in the past, that means it’s possible! Thus evidence for past climate changes in ENSO, ice sheets and the carbon cycle (for instance) demonstrate quite clearly that these systems are indeed sensitive to external changes. Therefore, assuming that they can’t change in the future would be foolish. This is basic, but not really useful in a practical sense.

All future projections rely on models of some sort. Dominant in the climate issue are the large scale ocean-atmosphere GCMs that were discussed extensively in the latest IPCC report, but other kinds of simpler or more specialised or more conceptual models can also be used. The reason those other models are still useful is that the GCMs are not complete. That is, they do not contain all the possible interactions that we know from the paleo record and modern observations can occur. This is a second point – interactions seen in the record, say between carbon dioxide levels or dust amounts and Milankovitch forcing imply that there are mechanisms that connect them. Those mechanisms may be only imperfectly known, but the paleo-record does highlight the need to quantify these mechanisms for models to be more complete.

The third point, and possibly the most important, is that the paleo-record is useful for model evaluation. All episodes in climate history (in principle) should allow us to quantify how good the models are and how appropriate are our hypotheses for climate change in the past. It’s vital to note the connection though – models embody much data and assumptions about how climate works, but for their climate to change you need a hypothesis – like a change in the Earth’s orbit, or volcanic activity, or solar changes etc. Comparing model simulations to observational data is then a test of the two factors together. Even if the hypothesis is that a change is due to intrinsic variability, a simulation of a model to look for the magnitude of intrinsic changes (possibly due to multiple steady states or similar) is still a test both of the model and the hypothesis. If the test fails, it shows that one or other elements (or both) must be lacking or that the data may be incomplete or mis-interpreted. If it passes, then we a have a self-consistent explanation of the observed change that may, however, not be unique (but it’s a good start!).

But what is the relevance of these tests? What can a successful model of the impacts of a change in the North Atlantic overturning circulation or a shift in the Earth’s orbit really do for future projections? This is where most of the attention is being directed. The key unknown is whether the skill of a model on a paleo-climate question is correlated to the magnitude of change in a scenario. If there is no correlation – i.e. the projections of the models that do well on the paleo-climate test span the same range as the models that did badly, then nothing much has been gained. If however, one could show that the models that did best, for instance at mid-Holocene rainfall changes, systematically gave a different projection, for instance, of greater changes in the Indian Monsoon under increasing GHGs, then we would have reason to weight the different model projections to come up with a revised assessment. Similarly, if an ice sheet model can’t match the rapid melt seen during the deglaciation, then its credibility in projecting future melt rates would/should be lessened.

Unfortunately apart from a few coordinated experiments for the last glacial period and the mid-Holocene (i.e. PMIP) with models that don’t necessarily overlap with those in the AR4 archive, this database of model results and tests just doesn’t exist. Of course, individual models have looked at many various paleo-climate events ranging from the Little Ice Age to the Cretaceous, but this serves mainly as an advance scouting party to determine the lay of the land rather than a full road map. Thus we are faced with two problems – we do not yet know which paleo-climate events are likely to be most useful (though everyone has their ideas), and we do not have the databases that allow you to match the paleo simulations with the future projections.

In looking at the paleo record for useful model tests, there are two classes of problems: what happened at a specific time, or what the response is to a specific forcing or event. The first requires a full description of the different forcings at one time, the second a collection of data over many time periods associated with one forcing. An example of the first approach would be the last glacial maximum where the changes in orbit, greenhouse gases, dust, ice sheets and vegetation (at least) all need to be included. The second class is typified by looking for the response to volcanoes by lumping together all the years after big eruptions. Similar approaches could be developed in the first class for the mid-Pliocene, the 8.2 kyr event, the Eemian (last inter-glacial), early Holocene, the deglaciation, the early Eocene, the PETM, the Little Ice Age etc. and for the second class, orbital forcing, solar forcing, Dansgaard-Oeschger events, Heinrich events etc.

But there is still one element lacking. For most of these cases, our knowledge of changes at these times is fragmentary, spread over dozens to hundreds of papers and subject to multiple interpretations. In short, it’s a mess. The missing element is the work required to pull all of that together and produce a synthesis that can be easily compared to the models. That this synthesis is only rarely done underlines the difficulties involved. To be sure there are good examples – CLIMAP (and its recent update, MARGO) for the LGM ocean temperatures, the vegetation and precipitation databases for the mid-Holocene at PMIP, the spatially resolved temperature patterns over the last few hundred years from multiple proxies, etc. Each of these have been used very successfully in model-data comparisons and have been hugely influential inside and outside the paleo-community.

It may seem odd that this kind of study is not undertaken more often, but there are reasons. Most fundamentally it is because the tools and techniques required for doing good synthesis work are not the same as those for making measurements or for developing models. It could in fact be described as a new kind of science (though in essence it is not new at all) requiring, perhaps, a new kind of scientist. One who is at ease in dealing with the disparate sources of paleo-data and aware of the problems, and yet conscious of what is needed (and why) by modellers. Or additionally modellers who understand what the proxy data depends on and who can build that into the models themselves making for more direct model-data comparisons.

Should the paleo-community therefore increase the emphasis on synthesis and allocate more funds and positions accordingly? This is often a contentious issue since whenever people discuss the need for work to be done to integrate existing information, some will question whether the primacy of new data gathering is being threatened. This meeting was no exception. However, I am convinced that this debate isn’t the zero sum game implied by the argument. On the contrary, synthesising the information from a highly technical field and making it useful for others outside is a fundamental part of increasing respect for the field as a whole and actually increases the size of the pot available in the long term. Yet the lack of appropriately skilled people who can gain the respect of the data gatherers and deliver the ‘value added’ products to the modellers remains a serious obstacle.

Despite the problems and the undoubted challenges in bringing paleo-data/model comparisons up to a new level, it was heartening to see these issues tackled head on. The desire to turn throwaway lines in grant applications into real science was actually quite inspiring – so much so that I should probably stop writing blog posts and get on with it.

The above condensed version of the meeting is heavily influenced by conversations and talks there, particularly with Peter Huybers, Paul Valdes, Eric Wolff and Sandy Harrison among others.


523 Responses to “Back to the future”

  1. 51
    Dave Werth says:

    I wonder if the record setting sea ice melt last year perhaps allowing a large transfer of heat from the atmosphere to the arctic ocean is a factor (along with la nina) in the cold winter we’ve had in the northern hemisphere this year. Has there been any research done on this?

    It seems to me a measurement of the “total energy” in the earth system would be useful to show trend of climate change. It should include not only the heat stored in atmosphere, ocean and land but the energy stored in the biosphere and even the energy in currents and winds if it’s significant. Just a thought.

  2. 52
    gusbobb says:

    • Martin Vermeer Says: “The temperature variation of El Nino doesn’t require heat as much as it requires a very large area in the Pacific to be a little bit warmer at the surface.”

    In other words Martin the temperature change is not a function of increased heat content but a function of its distribution and therefore an artifact of the measuring methodology? That certainly raises questions regards to the value of temperature as a measure of the earth’s energy balance.

    • Ray Ladbury Says: ”And you seem to be missing the point entirely. OK, so let’s say there is a flux of cold water to the surface to suck up heat for a decade. All that means is that you won’t see the type of warming we’ve had for the last 20 years for a decade. At the end of that time, the CO2 is still there and warming kicks off again with a vengeance. What is so hard to understand about this? Climate consists of long term trends, neglecting short-term variability “
    Well put Ray and exactly my point. Climate consists of long term trends neglecting short-term variability. Researchers like Okasofu argue that we have had a linear increase in temperature and sea levels starting from the early 1700’s before CO2 became a factor. See Figures 3, 4,5, 6 and 10 from his paper.

    http://www.iarc.uaf.edu/highlights/2007/akasofu_3_07/Earth_recovering_from_LIA.pdf

    And such a trend would be in keeping with the historical sunspot record. And Ray to say the sun cycle is just 11 years is your personal arbitrary distinction. If you include solar magnetic field reversals you must say the cycle is at least 22 years. And obviously from changes since the Maunder minimum or evidence for other minima there is obviously a change in the number of sunspots at each ~11 year maximum.Your 11 year cycle may be considered solar weather – not solar climate. I am suggesting Ray that the point is anything less than 300 years is weather. And in that case solar trumps CO2.

    http://earthobservatory.nasa.gov/Library/SORCE/Images/sunspot_number_1611_rt.gif

    Most people have no problem linking solar change to increased temperatures but then argue that since 1985 it has decoupled. But how much of that recent increase is short term variation? We have had 5 El Ninos since 1985 with a big 1998 peak in an El Nino year. As Martin points out you don’t need more OHC, just a redistribution that allows us to measure that heat differently. Combine that with the warm bias of the XBT’s that proliferated during this period we have to wonder if the sun really decoupled from OHC. If we subtract these short term variations from the long term trend that Oksofu presents there is not much warming left to attribute to AGW.

    Ray you are suggesting that the oceanic variability is due to cold water sucking up the heat. But Since 2003 there doesn’t appear to be an increase in OHC, so maybe there is other intrepretations to this story. If Okasofu’s trend is correct and if the driver of that trend is solar which correlates well for most of the past 300 years, and if this dearth of sunspots continues we may be entering a minimum and then you will not see warming like the past 20 years for another 100 years. You must have bumped into David Hathaway hanging around NASA. I bet he would admit that the current low solar activity is unlike any he has observed.

  3. 53
    Geoff Wexler says:

    Having more paragraphs is an improvement.

    I wonder if it might also be possible to provide us readers with an extra feature, i.e. a TOPIC button which would enable us to concentrate on the subset of comments which the monitor has decided are closely relevant to the lead article? Less relevant comments would not be displayed. Then those who prefer to read the unsorted mixture would simply avoid the new button.

    [Response: nice idea – anyone know any relevant plugins? – gavin]

  4. 54
    Vincent van der Goes says:

    This all sounds like an extremely exciting area of research to me. Being a freshly graduated ICT student (Leiden University, Holland), I wonder if I would have the right kind of background to consider this as subject for a PhD thesis? I do have a somewhat above-average background in math and physics for an ICT graduate (got a Bachelor degree in astrophysics).

  5. 55
    Dodo says:

    Gavin, you are on the record with a prediction that global temps will rise above the 1998 record in five years, by 2013. And if my memory doesn’t fail completely, you also said that that would constitute some kind of falsification of some AGW hypotheses (à la Pielke Jr.). Now, in light of the Keenleyside et al. paper in Nature, it would be interesting to hear your thoughts on what to expect in 5, 10 or 20 years, and if you would want to refine the falsification criteria somewhat.

    [Response: No. They don’t show annual data or predict ENSO, and it is almost certainly the case that the next big El Nino will put us over 1998 (again). Plus this is only one paper and which did not demonstrate that their method was any good at matching global mean temperatures – their standard run does much better (see fig 4). – gavin]

  6. 56

    gusbobb writes:

    I also find it amusing that cool spells due to ocean circulation and oscillations are not seen as “climate change” as the reports on the new cooling predictions suggest but road bumps to inevitable warming.

    You never had a course in statistics, did you?

  7. 57
    John Mashey says:

    re: 52 gusbobb
    Dr. Akasofu: Can you recognize when a highly-respected aurora researcher, after retiring, starts opining about climate science without apparently knowing even the minimal basics? Apparently not, if you quote that paper.

    See analysis of that paper, my post as of May 17, 2007 5:03 am.

    My summary says:
    “This paper is not remotely credible, and it’s sad to see a respected scientist fall into this.”

  8. 58
    Ron Taylor says:

    In 39 Ray Ladbury says: “OK, so let’s say there is a flux of cold water to the surface to suck up heat for a decade. All that means is that you won’t see the type of warming we’ve had for the last 20 years for a decade. At the end of that time, the CO2 is still there and warming kicks off again with a vengeance. What is so hard to understand about this? Climate consists of long term trends, neglecting short-term variability.”

    Ray, let me suggest an idea that might help, but may be too oversimplified.

    Even if ocean currents bring cold water to the surface, thus causing a plateau or drop in mean global surface temperature, that does not mean global warming has stopped – only surface warming has. In fact, one could argue that global warming would increase, since the cooler surface, especially of the ocean, would radiate less IR to space, thus increasing the energy imbalance, and accelerating the rate of heat accumulation. Where does this heat go? It warms these cooler waters, increasing the heat energy content of the oceans. One consequence would be to increase the rate of sea level rise, though probably by a miniscule amount. Also, that heat does not go away, but is there in the ocean and will make itself felt, sooner or later. It might, for example, increase the rate of melting of the WAIS.

    I did a brief Google Scholar search, but could not find anything conclusive about a possible negative feedback if the cooler water generated more fog of a type that had a higher albedo than the open water.

  9. 59
    Ray Ladbury says:

    Gusbob says: “I am suggesting Ray that the point is anything less than 300 years is weather. And in that case solar trumps CO2.”

    Wrong! Solar changes happen on a timescale of decades. See, for example:
    http://arxiv.org/PS_cache/arxiv/pdf/0706/0706.0385v1.pdf

    CO2 persists on a timescale of centuries.

  10. 60
    Aaron Lewis says:

    Hank,
    “Research well underway” suggests appropriate levels of concern by policy makers resulting in appropriate funding. I do not see appropriate levels of concern. I do not see appropriate levels of funding.

    The only thing that I can hope is that this summer’s sea ice melt (and resulting distress to polar bear populations) arouses great concern, resulting in great actions.

    Plot Arctic sea ice area in terms of standard deviations, and it is clear that the Arctic Sea Ice System is “out of control.” It is a system seeking a new equilibrium. Volumes of GIS affected by melt conditions are increasing exponentially, but are harder categorize statistically. However, exponential change is not typical of systems in equilibrium. Thus, I think we can assume that the GIS is out of equilibrium. That means that Hansen is correct that we are above GHG concentrations that trigger ice sheet melt and he understats rates of heat transfer to the ice.

    If policy makers had a proper sense of urgency we would have 150,000 graduate students deployed to Greenland pointing their thermometers and stain gauges at everything; and in their spare time they would be measuring every kind of phase transition that might be occurring.

    Am I paranoid? Yes, because we really do not have a very good understanding of how ice transitions to water in the pressure ranges found at the bottom of an ice sheet, and there is a big difference between the structural strength of ice, and the structural strength of water.

    Tell me again, How much potential energy is there in a nuclear bomb? And, How much potential energy is there in an ice sheet? Yes, the 2% rule applies.

  11. 61
    Rich Creager says:

    BBP (36)

    The sun loses quite a bit more mass through the solar wind outflow than to mass-energy conversion, tho it still seems inconsequential in terms of climate change.

  12. 62
  13. 63

    #52 gusbobb:

    In other words Martin the temperature change is not a function of increased heat content but a function of its distribution and therefore an artifact of the measuring methodology? That certainly raises questions regards to the value of temperature as a measure of the earth’s energy balance.

    You got that last one somewhat right, gusbobb. Global mean temperature is a noisy measure of global heat content, the noise being precisely natural variations in circulation patterns like El Nino/La Nina. But what you got wrong is that it is a measure, warts and all. As long as the Earth’s heat energy budget is in imbalance, as it is, due to anomalous greenhouse forcing, the total heat content of the Earth will grow, and much of that heat will end up in the reservoir with the greatest heat capacity, the deep ocean.

    As Martin points out you don’t need more OHC, just a redistribution that allows us to measure that heat differently.

    Based on the above misunderstanding.

    I see John Mashey took care of Dr Akasofu. Gusbobb, please allow more curiosity to inform your scientific reading appetite. Google Scholar is your friend, and while Dr Akasofu put his name to many space plasma physics papers two decades ago — and those may well be worthwhile reading — he has nothing to contribute to the current discussion.

  14. 64
    Stormy says:

    One of the clearest statements of the problem that I have read.

  15. 65
    Ron Taylor says:

    If the PDO and AMO are both moving into a cool phase, with cooler water being brought to the surface, doesn’t that mean the warmer water which had been at the surface has been taken deeper by the currents? Continuity of mass would seem to require that.

    I am not sure what depth scale the currents cover, but this could lead to fairly abrupt warming of the ocean down to depths of perhaps a few hundred meters. That is exactly the kind of thing that could accelerate the loss of the WAIS, assuming that this applied to the waters around Antarctica. I understand there is already a problem with warmer waters reaching the underside of the ice shelves.

    It seems to me that cool phases for the PDO and AMO may not be the denialist’s friend many think it is.

  16. 66
    gusbobb says:

    Ray Ladbury Says: “Wrong! Solar changes happen on a timescale of decades.”

    I don’t understand your quibbling. Ray the article you refer to clearly shows solar changes happening at timescales greater than your 11 year constraint and is more supportive of my arguments than yours. Here are a few snips:

    “The distribution of the duration of grand minima is bimodal, with a dominance of short (30-90 yr) Maunderlike minima and a smaller number of long (longer than 110 yr) Sporer-like minima.”

    “The Sun spends around 3/4 of the time at moderate magnetic activity levels (averaged over 10 years). The remainder of the time is spent in the state of a grand minimum (about 17%) or a grand maximum (9% or 22% for the SN-L or SN-S series, respectively). The solar activity during modern times corresponds to the grand maximum state.”

    “This suggests that a grand minimum is a special state of the dynamo. Once falling into the grand minimum as a result of a stochastic/chaotic but non-Poisson process, the dynamo is ”trapped” in this state and its behavior is driven by deterministic intrinsic features.”

    Ray if you are limiting solar change to cyclic behavior that is easier to model, then fine.. If we are talking solar changes that affect climate, and allow us to interpret paleoclimates, then to limit a model to 11 years will cause misleading interpretations regards solar effects on climate. And it is also why the consensus missed the meagerness of this new sunspot cycle.

    I totally agree with Usokin et al (2007) paper. Our record high temperatures correlate well with the fact we have been experiencing a less common grand maximum clearly visible in the paper. Solar effects deserve greater attribution.

    They mention these chaotic solar changes are a challenge for the solar dynamo theory and I totally agree. I suspect the stochastic processes affecting the sun are related to our travel through varying interstellar medium. But that is another discussion.

  17. 67
    Ray Ladbury says:

    Gusbob, My point is that the timescales of solar variability are short compared to CO2. What is more, the changes in insolation are not typically large. And what is more, the solar output is independent of the forcing by CO2. They are determined independently. A GCM is not a Chinese takeout menu. You can’t just take one from column A, one from column B… If you want a world where sensitivity is less than 3 degrees per doubling, you’ll have to go back to all of the evidence that supports that value and show why it is wrong.

    “I suspect the stochastic processes affecting the sun are related to our travel through varying interstellar medium. But that is another discussion.”

    Horse Puckey!

  18. 68
    gusbobb says:

    # Ray Ladbury Says: And what is more, the solar output is independent of the forcing by CO2. They are determined independently. ”

    Well duhh they are independent. However attribution of recent temperatures is not. Underestimates of attribution by solar could lead to mistaken attribution by CO2.

  19. 69
    David B. Benson says:

    For what it is worth in the current phase of the discussion, a determination of the power spectrum of the temperature variations in the GISP2 ice core data from Central Greenland over the Holocene show a significant peak in the 162 year band plus side-bands. There is also a small peak in the 65 year band. I suppose the latter is from the PDO.

    I’m not finding any other even potentially significant peaks for further exploration.

  20. 70
    Dodo says:

    Re 55. (Gavin) Thanks for the reply, and sorry for the clumsy formulation in my question. I’ll try again: Just in case, IF no new global temperature records are NOT set by 2013 or 2018, what would you conclude from that?

    [Response: The double negative makes your point a little hard to decipher. But if you mean what happens if there isn’t a new record, then I’ll be embarrassed and my predictive skills will be publicly scorned. In the meantime of course model development will continue – this isn’t something that varies because of the annual temperature anomaly, and it remains to be seen whether more up-to-date models would have predicted something different. My guess is that they won’t (since projections with similar forcings have been stable for a couple of decades). However, we will also likely have better estimates of the forcing fields – aerosols, land use etc. – that will cover the current period and so that might make a difference. – gavin]

  21. 71
    Ray Ladbury says:

    Gusbob, NO! If CO2 forcing is fixed, then even if solar forcing is rising there would have to be another forcer of opposite sign so that the net forcing remained the same. And CO2 forcing is for all practical purposes fixed. It’s not a Chinese menu. You can’t make substitutions. So, you would have to provide not one but two mechanisms. And since we can control CO2, but not solar, which one would you attribute the warming to?

    Look, what you are saying is that if I have x+2=5, that 2 must be smaller than its known value because you contend that x is larger than three. You can’t conduct algebra in the limit of small 2, just as you can’t diminish CO2 forcing below the levels where it is currently constrained without explaining why the constraints are wrong.

  22. 72
    Hank Roberts says:

    Gavin, you asked about ways to hide off-topic comments.

    There’s no threaded newsreader for blogs (sigh) yet.

    Killfile works but only for readers using Firefox. Invaluable!
    (Scienceblogs uses it)
    — killfile http://userscripts.org/scripts/show/4107
    “… for … livejournal, haloscan comments, most typepad blogs, most blogspot blogs, scienceblogs.com, and more as I add them.”

    Or, hand-editing a ‘dungeon’ thread (moving offtopic posts to a thread instead of just deleting them)

  23. 73
    gusbobb says:

    • Ray Ladbury Says: “Look, what you are saying is that if I have x+2=5, that 2 must be smaller than its known value because you contend that x is larger than three. You can’t conduct algebra in the limit of small 2, just as you can’t diminish CO2 forcing below the levels where it is currently constrained without explaining why the constraints are wrong.”

    That’s not at all what I m saying. Why do you persist in telling me what I am saying? Please keep your straw dogs on a leash.

    The real algebra is a tad more complex and helps explain why CO2 often lags temperature changes. If we assume for a moment that CO2 is a result of temperature change instead of a driver of temperature change, then we can easily see that solar induced decreases in ocean temperatures 1) increases CO2 solubility and 2) decreases the potential energy stability of the ocean by decreasing surface temperatures and allows greater vertical mixing.

    I believe the estimates of change in SST since the early 1800’s approaches 1 degree C and a back of the envelope calculation would suggest that increased solubility may change atmospheric concentrations by 40-60 ppm. Add in vertical mixing and uncertainties due to biological responses and other natural variations, and by the time the sun starts increasing its activity following a minimum, atmospheric concentrations may have dropped low enough that warming will definitely not return with a vengeance, but follow the sun. Such a scenario is certainly supported by ice core data showing CO2 follows changes in temperature. Seldom does the evidence show CO2 leading temperature change.

  24. 74

    Re #71 Ray,

    Depends what you take for efficiency of the different forcings + feedbacks.

    As already said in several discussions, current GCM’s assume that a change in solar forcing has more or less the same effect (efficacy) as an equal change in forcing from GHGs. But there are several indications that changes in solar forcing have more impact that changes in GHG forcing… Thus what we have is a different equation:

    dT = f1(dFsolar) + f2(dFghg)

    where the factor f1 and f2 may be quite different, because of different feedbacks. Solar changes have their maximum influence in the tropical stratosphere in the UV range, which changes the ozone layer thickness, the position of the jet streams, and cloud and rain amounts and patterns (empirically proven). GHGs have their main influence in the lower troposphere more towards the poles as IR downwelling, with unclear influence on clouds (still troubling for GCMs) and temperature/rain patterns…

    Any past trends can be explained by any combination of weight factors for solar and GHGs once you stop using similar efficacies for different forcing sources…

  25. 75
    John Mashey says:

    re: 72 Hank
    I’d guess that just as troll-frequency tends to minish if they’re ignored or their posts are deleted, I’d expect that the existence of a dungeon thread and a willingness to use it would tend to lessen the need for its use.

  26. 76
    Jim Cripwell says:

    In #65, Rod Taylor writes “If the PDO and AMO are both moving into a cool phase, with cooler water being brought to the surface, doesn’t that mean the warmer water which had been at the surface has been taken deeper by the currents? Continuity of mass would seem to require that.” I am not sure that this is correct. If you assume that the amount of energy absorbed by the earth from the sun is constant, then I suspect that you are correct. But if, for some reason, the earth is absorbing less energy from the sun, then the PDO and AMO could be caused by this loss of energy. There is then no requirement for the warmer water to go anywhere. But I am not sure that my logic is correct.

  27. 77

    gusbobb writes:

    I suspect the stochastic processes affecting the sun are related to our travel through varying interstellar medium.

    I doubt it. The interstellar medium is many orders of magnitude less dense than even the solar atmosphere.

  28. 78

    gusbobb writes:

    # Ray Ladbury Says: And what is more, the solar output is independent of the forcing by CO2. They are determined independently. ”

    Well duhh they are independent. However attribution of recent temperatures is not. Underestimates of attribution by solar could lead to mistaken attribution by CO2.

    You appear to have quoted Ray without reading the quote, or at least without understanding it. CO2 attribution, CO2 forcing, is NOT “what’s left over after solar is taken into account.” It is determined INDEPENDENTLY of other factors. Independently means not dependent on, not related to, unaffected by.

  29. 79
    Ike Solem says:

    Gusbob says: “I think the ocean is a wild card regards heat distribution and climate predictions. I have advocated that since my first post.” “I was not predicting an El Nino or its effects. It was Gavin who predicted the next record high will be in a few years with an El Nino. My question is where does the heat come from to generate the spike in temperatures during the El Nino.”

    Well, the ocean is more predictable than the atmosphere, which is expected since the atmosphere mixing time is on the order of a few hundred days, while the ocean mixing time is on the order of hundreds of years.

    Thus, there are weather forecasts that are accurate on the order of days to weeks and there are ocean-atmosphere forecasts of El Nino and similar phenomena that are accurate on the order of months to years. These could be called weather and climate predictions of the first kind – initial-value problems.

    Then, there are climate/weather forecasts of the second kind, which involve “external variables” such as the chemical composition of the atmosphere, the amount of water locked up in the ice sheets, the shape of the ocean basins and the distribution of the land masses, and the orbital variations, i.e. the Milankovitch, forcings and so on. (The solar forcing has been flat, and since the climate system responds quickly to changes in solar forcing, thus we can rule out solar forcing as having any role in global warming over the past 60 years or so.)

    These climate models might be accurate on the scale of decades to centuries, but they do not attempt to model biosphere responses or carbon cycle changes – those are the “external variables” for the climate models. By comparison, the “external variables” for weather models are things like sea surface temperatures.

    We can imagine this as a three stage process –

    1) Set up a biosphere/carbon cycle model which estimates the future composition of the atmosphere and the amount of biomass as wetlands, forest, etc. on the planet.

    2) Use that output to set that “external variable” in the climate models, which will then produce estimates of future sea surface temperatures.

    3) Plug those SSTs into weather models with 2-week limits and see what kind of weather might be expected in a warmer world.

    There are some big uncertainties involved in model #1 – the largest being future human behavior.

  30. 80
    gusbobb says:

    # Barton Paul Levenson Says:”You appear to have quoted Ray without reading the quote, or at least without understanding it. CO2 attribution, CO2 forcing, is NOT “what’s left over after solar is taken into account.” It is determined INDEPENDENTLY of other factors. Independently means not dependent on, not related to, unaffected by.”

    I can calculate how much IR is absorbed per concentration of CO2 at a given temperature independently of other factors. However the climatic sensitivity is another story. When sensitivity is being calculated Hansen and others will include water vapor feed back. Clouds and water vapor effects are certainly not well modeled. Whatever effects you wish to attribute to cosmic rays, Svenmark has shown there is an observable impact on cloud cover. And cloud cover will effect our sensitivity equations. CO2 doesn’t trap heat like Al Gore [edit] portrayed in inconvenient Truth. CO2 delays re-radiation back into space. And that delay is affected by winds and clouds and convection currents.

    [Response: Svensmark did not “show” that there is an observable impact on cloud cover, and even if he did that’s not going to affect the trend because there ain’t no long term trend in cosmic rays. And your statement about how CO2 works bears no resemblance to the the way radiative transfer really works, which in fact is quite close to the cartoon in AIT. And we have thousands of observational confirmations that the way radiative transfer done is right. So don’t make me get impatient. To paraphrase The Hulk, “…and I don’t think you’ll LIKE me when I’m impatient.” –raypierre]

  31. 81

    Such a scenario is certainly supported by ice core data showing CO2 follows changes in temperature. Seldom does the evidence show CO2 leading temperature change.

    …and in related news, chicken cannot lay eggs because they have been observed to hatch from them :-)

    You’re talking about the glacial/interglacial cycle, gusbobb. Well documented thanks to the ice cores. I propose that you read up on our understanding of this cycle, which is easy thanks to the useful link on this site. Ever heard of a guy named Milankovich? You see, we know what caused those ice ages. And we also know what were the forcings and the feedbacks, even quantitatively. Go read up and stop embarrassing yourself. (Note that I am rhetorically assuming your honesty, in good debating tradition and for the benefit of other readers.)

    BTW the Milankovich forcing is currently going down (verrry slowly), and still it’s getting warmer. Different mechanism.

    …and CO2 is not leaving the ocean, but entering it. We know that for a fact too, by a simple bookkeeping exercise (I won’t mention the isotopic fingerprint evidence, keep it simple eh?): we know how much fossil fuel is being burnt, yet see appear only roughly half of that in the atmosphere, in the Keeling curve. The other half enters the ocean, where is is also observable as a lowered pH.

    You really need to read up, gusbobb, to stop making elementary errors that undermine everything you write. Science isn’t just stringing together fancy looking terms into syntactically correct sentences — that’s scienciness, not science. Science also has to make sense. You don’t. Until you get this, please do us all a favour and refrain from adding further noise to this blog.

  32. 82
    Ray Ladbury says:

    Gusbob, if you were to actually do the math, you’d find that a couple of degrees cooling will not raise CO2 solubility sufficiently to make a difference–and we’d give all that back when the temperature rose again.
    Doing the math–that’s what scientists do. They don’t just focus on plausibility arguments and spin.

  33. 83
    gusbobb says:

    Sorry to try your patience Raypierre but could you make the criticism more substantive. The AIT cartoon implied that CO2 traps the energy forevermore, and you seem to imply that such a notion is correct. So are you saying that once a CO2 molecule absorbs a photon of IR it remains in an excited state forevermore? That it doesn’t re-radiate that energy, roughly 50% back to earth and 50% back to space? I am very confused as to what you are suggesting. Perhaps if you could give the details of the observational confirmations that you refer to it will clear up my muddled thinking.

  34. 84
    John Mashey says:

    As a continuing student of blog behavior, in this RC thread, I observed that Tom Watson achieved a 27% blog-consumption rating.

    As of 82 posts:
    10 gusbobb
    14 replies (that I noticed)
    24 total of 82, or 29%

    and as I suggested in TW’s case, it is occasionally worth going back and reviewing a sequence of posts.

  35. 85
    gusbobb says:

    # Martin Vermeer Says:”Ever heard of a guy named Milankovich? You see, we know what caused those ice ages. And we also know what were the forcings and the feedbacks, even quantitatively. Go read up and stop embarrassing yourself. (Note that I am rhetorically assuming your honesty, in good debating tradition and for the benefit of other readers.)”

    Martin thanks for graciously reaffirming my honesty, although I am unsure why my honesty would be an issue. And I am very well aware of the Milankovich cycles. I did not understand however that you “knew” the exact quantities of forcing during those cycles. Seems like a lot of assumptions on sketchy data. Yes we can calculate changes in insolation do to orbital positions, wobble and so forth. But I understood RC believes the rest of the glacial cycles are due to CO2 forcing. The lag time however troubles me there. And rapid changes during Dansgaard-Oeshger events seemed to be problematic. Do you understand all the forcings for those events as well? It would be helpful if you are honestly trying to educate me, if you provided more detail criticism. Otherwise all I am hearing is that you all know and I don’t, therefore I should not talk. Not good educational tactics.

    # Martin Vermeer Says:”in the Keeling curve. The other half enters the ocean, where is is also observable as a lowered pH.” I am also very aware of the Keeling curve. The last time I looked the 2008 CO2 did not surpass the previous annual peak. I realize it is only for a very short period of time but in a time of increasing CO2 use, I find that peculiar. My first assumption was the cooling temperatures we have recently experienced were connected but I would honestly appreciate counter-arguments to such speculation.

  36. 86
    Chris says:

    Re #73: gussbobb

    just in case you’re being serious, it’s worth pointing out that:

    (a) since the entire glacial-present interglacial transition was associated with a global temperature increase of 5 – 6 oC (about right?) and atmospheric CO2 concentrations rose from 180-280 ppm, it’s rather more likely that the temperature-CO2 relationship that relates to temperature-dependent changes in ocean solubility is more like 17-20 ppm per oC (100ppm/5-6 oC) rather than your guess of 40-60 per oC.

    (b) that CO2 is certainly not coming out of the oceans in response to our current warming. In fact CO2 from our emissions is going into the oceans in prodigious amounts:

    e.g. Sabine et al (2004) The oceanic sink for anthropogenic CO2; Science 305, 367-371.

    or: Feeley et al (2004) Impact of anthropogenic CO2 on the CaCO3 system in the oceans; Science 305, 362-366.

    (c) that CO2 is a greenhouse gas and thus it’s enhanced atmospheric concentrations always leads to an enhanced warming forcing. Just because the initial phases of the glacial-interglacial cycles led the increased atmospheric CO2 levels (which is rather obvious and well-understood) doesn’t negate that straightforward fact. Perhaps a better means of assessing the temporal relationship between Earth’s surface temperature and raised greenhouse gas concentrations would be to look at the extinction events in the deep past, seemingly associated with massive release of greenhouse gases (e.g. the end-Cretaceous; the Paleo-Eocene Thermal Maximum; the Permian-Triassic extinctions; the Triassic-Jurrasic event and so on….)

    or why not consider the rather large late 20th century warming in relation to the preceding massive enhancement of the atmospheric CO2 concentrations starting especially from the mid-60’s…

  37. 87
    Hank Roberts says:

    Gusbob,

    Assuming you’re not intentionally misinterpreting what you read,
    Click here: http://www.realclimate.org/index.php/archives/2007/05/start-here/

    Clich here:
    http://www.aip.org/history/climate/index.html

    While people have been willing to retype that material for you, you’re blowing it off. Stop, please. Read, ask questions about the reading material after you’ve read it and failed to understand it.
    Or if you understand it, ask smarter questions based on understanding.

  38. 88
    L Miller says:

    I know I’m wasting my breath but I’ve had a half dozen drinks and I still have some time to kill before my friends get here.

    “If we assume for a moment that CO2 is a result of temperature change instead of a driver of temperature change, then we can easily see that solar induced decreases in ocean temperatures 1) increases CO2 solubility and 2) decreases the potential energy stability of the ocean by decreasing surface temperatures and allows greater vertical mixing.”

    It’s not either/or. CO2 is a feedback element; it is both output and input.

    Before you repeat yourself, no this does not imply hysteresis. While hysteresis can occur in non-linear feedback systems it is not guaranteed by any means and hysteresis doesn’t occur at all in linear feedback systems. What that means is that for a system to exhibit hysteresis it almost always has to cross a non-linear “tipping point” first.

    So, if we had an ice age that was caused by a decrease in solar output, it’s conceivable but not inevitable that the solar output would have to rise above it’s original level to get back to the original temperature. Since the ice ages cycles of the last million years are not connected to the amount of energy the earth receives from the sun there won’t be any well documented examples of this.

    “The AIT cartoon implied that CO2 traps the energy forevermore, and you seem to imply that such a notion is correct. So are you saying that once a CO2 molecule absorbs a photon of IR it remains in an excited state forevermore? That it doesn’t re-radiate that energy, roughly 50% back to earth and 50% back to space? I am very confused as to what you are suggesting. Perhaps if you could give the details of the observational confirmations that you refer to it will clear up my muddled thinking.”

    The AIT cartoon did not imply anything of the sort. Adding CO2 reduces the chance that an IR photon will make it out of the atmosphere. Since you need to have the same amount of energy exiting the top of the atmosphere as entering for stable temperature, the earth will warm until enough extra IR photons are created to make up for the ones blocked by CO2.

  39. 89
    Ray Ladbury says:

    John Mashey, I am afraid that some of us were raised in the “How many times must I forgive my brother,” and “Turn the other cheek” traditions, so if a troll asks what appears to be a sincere question, I am liable to answer it–as long as it does not stray too far off topic.

  40. 90
    Ray Ladbury says:

    Gusbob, You can find a good account of what happens to the energy in “A saturated gassy argument.” Basically, the energy remains trapped until the planet comes to a new equilibrium. The key thing to remember is that the photon gas tries to come into equilibrium (that is look like a black/grey body spectrum) with the gas where it can interact with the gas (e.g. absorption bands). Since there is an over-abundance of photons (i.e. they are coming from warmer areas down below, some of the photon energy has to go into kinetic energy of the gas to reach equilibrium. This happens quite easily with CO2 because the vibrational state has a lifetime on the order of microseconds, so collisional relaxation is more likely than radiative relaxation. I don’t know if this helps you, but try reading the saturated gassy argument piece.

  41. 91

    …I am unsure why my honesty would be an issue.

    Well, in my mind it hasn’t been an issue any more for some time… but like in Parliament, you don’t say that “The Hon. Rep. for X is making this up.”

    I post for the benefit of other readers who are honest and may be deceived by your talking points, believing that the science is in as messy a state as your misrepresentation of it.

    About teaching you, I am a modest guy… the other readers are referred to the link “What does the delay…” top right. Summary: there is one forcing, Milankovich, small; and two amplifying feedbacks, CO2 and albedo, both needed to make the books close, CO2 at a short term equilibrium doubling sensitivity of (not much less than) 3C. (The delay was originally estimated at 800 yrs, but now thought to be much smaller.)

    About your other talking points and change-of-subject/goalpost ping-pong, sigh, life is short. Undermining your credibility will have to do.

  42. 92
    Dodo says:

    Re 70. Gavin, thanks for the answer, and for ignoring the stupid double negative. Anyway, we have a very interesting decade to look forward to, with the new solar cycle, PDO switch and very likely business-as-usual GHG emissions. Whatever happens, let’s hope not too many people have to feel embarrassed or have their skills scorned. It is science, after all, not a betting game.

  43. 93
    asaguy says:

    In reconstructing paleo-climates is the shortened day (faster rotational speed)and larger radius at the equator factored in? Thanks for all of the info freely given.

  44. 94
    A. Simmons says:

    Totally off-topic… would someone please take a cluestick to The Register?

  45. 95

    Meanwhile, back in the present, we seem to have awaked the big monster (23 times more potent than CO2), who is poised to bear down on us. Methane is now gassing out off Siberia.

    See: http://www.climateark.org/shared/reader/welcome.aspx?linkid=97317

    And sooner than we think we may have quite definitively solved the denialists’ problem: do GHGs cause warming, as well as simply result from (lag behind) warming? Assuming there are any denialists left after this all plays out.

  46. 96
    gusbobb says:

    # Ray Ladbury Says:Gusbob, You can find a good account of what happens to the energy in “A saturated gassy argument.”

    I searhed “A saturated gassy argument” But got a link to a Portugese translation and comments but no article.

    [Response: click on the english/US flag icon on the bottom of the sidebar to reset your cookies to English versions. – gavin]

  47. 97
    Ron Taylor says:

    I agree with John Mashley (84). Note the revealing pattern of these comments in response to gusbob:

    “And your statement about how CO2 works bears no resemblance to the the way radiative transfer really works,…” Raypierre

    “just in case you’re being serious, it’s worth pointing out that…” Chris

    “Assuming you’re not intentionally misinterpreting what you read…” Hank Roberts

    “I know I’m wasting my breath but I’ve had a half dozen drinks and I still have some time to kill before my friends get here.” L. Miller

    “I post for the benefit of other readers who are honest and may be deceived by your talking points, believing that the science is in as messy a state as your misrepresentation of it.” Martin Vermeer

    “About your other talking points and change-of-subject/goalpost ping-pong, sigh, life is short. Undermining your credibility will have to do.” Martin Vermeer

    The frustration is evident and entirely justified.

  48. 98
    Chris says:

    Re #85 gusbobb, and your comment:

    [“# Martin Vermeer Says:”in the Keeling curve. The other half enters the ocean, where is is also observable as a lowered pH.” I am also very aware of the Keeling curve. The last time I looked the 2008 CO2 did not surpass the previous annual peak. I realize it is only for a very short period of time but in a time of increasing CO2 use, I find that peculiar. My first assumption was the cooling temperatures we have recently experienced were connected but I would honestly appreciate counter-arguments to such speculation.”]

    It might be mildly peculiar if it were true, but it isn’t: Here’s the updated Keeling curve for the local Mauna Loa observatory or globally averaged from the marine surface sites (scroll down a bit):

    http://www.esrl.noaa.gov/gmd/ccgg/trends/

    You can see that the 2008 atmospheric [CO2] is well above the previous annual peak.

    So counter-arguments to your speculation are unnecessary since your speculation is based on a false assumption.

  49. 99
    Steve Fish says:

    I also agree with #31 Harold Pierce’s suggestion regarding improved readability by limiting paragraph size.

    Another great improvement in readability would be to stop using undefined acronyms in posts. I am used to this in my own narrow area of scientific expertise, but such letter babble is inappropriate on a site intended for educating the public. It takes a lot of effort to understand a simple post if one doesn’t know what the words mean.

    Finally, although I have learned some information from the multiple responses to gusbob, they are getting repetitive. I suggest that the limited time of those who generously teach here would be more effective if some attention were shifted to the more straightforward and less provocative questions.

    Steve

  50. 100
    Ike Solem says:

    Gusbob says:
    “Sorry to try your patience Raypierre”

    I rather doubt that gusbob or tom watson or similar posters are sorry about that. As John Mashey points out, such posters are here mainly to disrupt the overall discussion and are deliberately intending to try people’s patience by bringing up discredited claims over and over again. Such posters on realclimate often succeed in steering the thread into some oft-refuted corner, some leading examples being the radiative physics of CO2 in the atmosphere, and the role of any solar variation in recent global warming. Those were the two topics that tom watson and gusbob latched onto, respectively (as well as Martin Lewitt).

    However, most readers of this blog should be able to recognize that gusbob statements like “Most people have no problem linking solar change to increased temperatures but then argue that since 1985 it has decoupled” are simply dishonest.

    It is always worth remembering that between 1998 and 2005, ExxonMobil granted some $16 Million to “Global Warming Skeptic” organizations, according to UCS. Further millions are coming from the coal industry. (1)

    A study by the Union of Concerned Scientists found that “virtually all of them publish and publicize the work of a nearly identical group of spokespeople, including scientists who misrepresent peer-reviewed climate findings and confuse the public’s understanding of global warming. Most of these organizations also include these same individuals as board members or scientific advisers.”

    “Firefighters’ budgets go up when fires go up,” explains Fred L. Smith, head of the Competitive Enterprise Institute.

    The posters here follow a typical pattern – they’ll ask questions that seem reasonable, and once they get a response, they bring up all kinds of ridiculous notions (solar forcing, bad physics, etc.). The primary goal is just “creation of the appearance of scientific uncertainty.”

    The best response to this is just to go back to the original topic of the post, which is a lot more interesting than PR efforts (those are handled over at desmogblog).

    The reason why paleo-climate information may be key in these cases is because all of these climate components have changed in the past. If we can understand why and how those changes occurred then, that might inform our projections of changes in the future. Unfortunately, the simplest use of the record – just going back to a point that had similar conditions to what we expect for the future – doesn’t work very well because there are no good analogs for the perturbations we are making. The world has never before seen such a rapid rise in greenhouse gases with the present-day configuration of the continents and with large amounts of polar ice. So more sophisticated approaches must be developed and this meeting was devoted to examining them.

    So, we are changing the atmospheric CO2 levels (and CH4 and N2O) at a rate some 30X greater than anything ever seen in the Antarctic core record. (2, 3) What kind of uncertainty does that inject into the predictions of global climate models that are largely tested based on their ability to predict past and present climate changes?

    When you take a system and force it harder and faster than it has been forced in millions of years, once should probably expect to see some unusual nonlinear behavior. This kind of uncertainty really affects the high end of possible climate responses – the incidence of weather extremes, the spread of ocean anoxia – radical changes not seen in millions of years, in other words.

    Slowing the rate of global warming by halting the use of fossil fuels really is the only way to reduce the probability of truly catastrophic climate changes.

    1) DesmogBlog: Clearing the PR Pollution that Clouds Climate Science
    http://www.desmogblog.com/

    2) J. Jouzel, et al. (2007) Orbital and Millennial Antarctic Climate Variability over the Past 800,000 Years, Science 317, 793.
    http://www.climate.unibe.ch/~stocker/papers/jouzel07sci.pdf

    3) The Keeling CO2 curve, updated to 2007 (notice the slight exponential shape, so far?):
    http://www.esrl.noaa.gov/media/2007/img/co2_data_mlo.2007.m.gif


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