4. Prosecuting in strict accordance with the Scientific Method.

by Eric Grimsrud

It is time to move this debate forward. As the Prosecutor I will now attempt to do that in strict accordance with the Scientific Method, a portion of which Ed has previously summarized in his Post #2.

To the Jury:

In science, we have theories and we have observable facts. Our understanding of gravity, for example, is based on both theory and facts. In this case, the facts have become known as the Laws of Gravity (a set of equations) while the theory is the sort of thing that Einstein unsuccessfully wrestled with in his attempt for develop a Unified Field Theory. Theories differ from facts, of course. Theories never becomes facts. Theories are just models of a given physical system that attempt to explain to behavior of that system. Therefore, even the very best of all theories ever developed for any physical systems remain “just theories” and can never be proved to be factual or the ultimate expression of truth. The only outcome for theories is that they either survive after being tested by observable facts or they are shown to be incorrect by those tests. If the latter occurs, then we know that the theory is either completely or partially incorrect. Upon adjustment, the theory can then be retested.

Now let’s consider the theory that suggests that the combustion of fossil fuels will lead to increased levels of atmosphere CO2, which in turn will cause increased global temperatures (please see my opening statement for a summary of the basics of this concept). Let’s call it the AGWFFC Theory (for Anthropogenic Global Warming by Fossil Fuel Combustion Theory).

Now let me first provide a short list of a few of the observable measurements that we might use to test this AGWFFC Theory. These measurements might address the follow questions.

1. Has fossil fuel combustion increased during the Industrial Age of Man?
2. Has the concentration of atmospheric CO2 increased during that period?
3. How has the global average temperature changed during this period.
4. What other factors also effect global temperatures and must also be considered in answering question 3 above?

Now let me stop there for the moment acknowledging that this list of observables only constitutes a starting point. Concerning this short list, I am prepared to address any questions of statement the Defense might have concerning them. I will not risk potentially boring you with any details, however, unless specifically requested to do so by the Defense. Also, I will readily admit at the onset that we can find that any facts in this initial step that are in contradiction of the AGWFFC Theory, we will have already found a basis for discarding this Theory and can all go home.

If the theory holds up in this initial phase, however, we can then move on to consider additional tests of the theory that either the Defense or Prosecution might envision. And after that, we can move on to the more difficult questions concerning the quantitative details predicted by this theory. While I recognize that some of you members of the jury might be impatient and wish we could jump immediately to the last point just mentioned, let me remind you that the Defense has insisted on following a strict form of the Scientific Method and I will comply with that request, proceeding one careful small step at a time, unless instructed to do otherwise.

Now I am going to turn the floor over to the Defense for their response at this time. Specifically, if they would like me to provide evidence concerning points 1 to 4 listed above, I will be glad to do so. Also, if they want to provide such evidence in any other these areas that would be fine with the Prosecution – especially if that would prove the AGWFFC Theory to in incorrect. In that case, the AGWFFC theory will have been shown to be incorrect. The trial might then be over and we all could go home.

So where do we go from here? I’ll leave that to the Defense. I am open to any baby steps the Defense might request – in order to remain in strict compliance with a rigorous interpretation of the Scientific Method – or whatever leaps of procedure the Defense now might like to suggest.

22 thoughts on “4. Prosecuting in strict accordance with the Scientific Method.”

  1. Dr. Eric,

    Thanks for your latest post.

    I don’t see how items number 1 – 3 on your list “test” the AGWFFC theory. They are just data that can be observed. For my part I am willing to stipulate to the following.

    1. Has fossil fuel combustion increased during the Industrial Age of Man?
    Yes, of course.

    2. Has the concentration of atmospheric CO2 increased during that period?
    Yes.

    3. How has the global average temperature changed during this period.
    It has gone up approximately 1 degree Celsius.

    There are an infinite number of answers to #4. Some likely candidates would be changes in solar irradiation, changes in ocean currents, changes in earth’s orbit and/or rotation, changes in land use, volcanism, etc. etc. And I am willing to further stipulate that an increase in greenhouse gases may have contributed as well.

    But I would also contend that whatever the natural or anthropogenic reasons global mean temperature has increased over the past 150 years, it has not been abnormal in either rate or amount, relative to other time periods in the current interglacial. Would you agree?

    As you said, “so where do we go from here”?

    1. To simplify things for the record, I agree with Matt's three stipulations and I think we can easily come to an agreement on the quantities in each case. Therefore, I do not see these three points becoming issues of disagreement.

      The only possible issues of disagreement related to these points will be in their cause-effect relationships: How much change in A was responsible for causing how much change in B?

  2. I have said it on this and other blog sites that items 1-3 are circumstantial evidence, thus Item 4 and its details are where the real test begins.. As part of this test it is my contention that until the "hypotheses of the greenhouse gas effect " is defined and tested the AGWFFC theory is a "Mother Goose rhyme." . We have to define (reexamine) what was proposed by Fourier,Tyndall and Arrhenius,and Michael Mann,and others ,this is the foundation of the AGWFFC theory and it is a foundation of Quicksand.

    1. Berthold,

      The way I see this shaping up, if I use Q(n) to identify the quantities versus time of each of Dr. Eric's points:

      Q(2) = function (Q(1), Q(4))
      Q(3) = function (Q(2), Q(4))

      Now, because we promised to try to make our comments understandable to those not familiar with the kind of scribble I just wrote, here is my textual explanation:

      CO2 concentration Q(2) in any year is a function of CO2 production Q(1) in any year and also a function of a whole bunch of other factors Q(4) that will make this simple exercise become complicated. Plus we may have to deal with time delays between cause and effect.

      Then we must deal with the second connection:

      Temperature Q(3) in any year is a function of CO2 concentration Q(2) in any year and also a function of a whole bunch of other factors Q(4) that will make this simple exercise become complicated. Plus we may have to deal with time delays between cause and effect.

      This is a hint about where this is leading.

      This is why it is important to get a good night's sleep before jumping into this. It is more important to be correct than to be quick.

  3. As a terrible typist and speller , I regularly either compose my responses on a Word document or copy it from the web and then paste to a Word document for spell check and grammar. This also allows me the option to save to separate files for later use.

  4. Dr Grimsrud,
    As an engineer by training, I have made my living discerning between good data that accurately represents the event in question and data that might at first appear useful but in the end leads the recipient to draw incorrect conclusions because it was in fact not an accurate representation of the event at all. My 34 years has taught me that data is more often flawed than accurate though most of the technical community never bothers to go through the painful process of verification. So with every passing year in industry I become more skeptical of data presented as fact until I know how it was collected and verified. You and Dr Berry seem to be in agreement, as are perhaps most of the other readers of this debate, that global temperature has increased measureably since approximately 1850 as you have noted in point #3 above. Since the community of environmental scientists takes this as fact, I presume it would be a simple matter for you to provide for me references, not only to the raw data, but a detailed explanation of how the data was collected. Specifically, my greatest curiosity is in regard to the location of the measurements around the globe. A truly good temperature collection study of the entire globe over the time period of interest should include a regularly spaced grid of data points collected at regular intervals of time. Such data seems unlikely to be available over the time span of concern. I understand statistical methods may be used to estimate gaps but I'm not ready to make the assumption this was done with any genuinely robust technique. If you would be so kind, please provide me references to this basic data and methodology.

    1. In my experience, when a quantity is desired to be known well, especially after examination of declared values from a number of independent sources show significant disagreement, the serious parties undergo their own survey or measurement with more carefully controlled instrument calibrations and controlled measurement conditions. Often a worldwide program is instituted. Thus the "International Geophysical Year (IGY) was done a few decades ago.

      This, I have not seen exemlified all during the CW, CC and CAT arguments of just the past year or two… "Vast progrms with Half-Vast ideas", I say.

      Thermal measurements to represent the atmospheric temperature need to be made with a 95% confidence interval (about three-sigma) of not more than 0.25 degrees C. Some may demand a three-sigma precision + bias ("reproducibility") to be not more than 0.1 degree C. I venture to say that such 95% reproducibility is abut one degree C (three-sigma) at most weather stations. The thermometer calibrations are tighter than that, but air circulation sampling and station vulnerability to heat from nearby surfaces and buildings need to be controlled and standardized, say that the observation stand or tower is 3m high and in the center of an acre-sized grassy field, etc. Does anyone know the NOAA specs? Calibration of CO2 concentration meters that can be flown anywhere at any altitude is another factor to be considered in arguing parameter measurements for CO2 distribution in our atmosphere. I have seen no data reporting these precisions.

      The task of proving the prosecution's case is overwhelming.

      If they care not to prove it, then why should we accept it?

  5. Leonard Weinstein

    Dr. Eric,
    Your point 1 is obviously true. Point 2 is almost surely at least partially true, but papers such as Beck's and papers on stomatal response make the relative increase less certain. Point 3 is a bad one. Correlation does not prove causation. There are several parameters that correlate much better to the temperature rise than CO2 increase (long term ocean currents, solar spots, etc). Point 4 is, in my opinion, not even close to supporting AGWFFC.

    1. Leonard,

      I did not intend to say at this point what conclusions would be drawn from that sort of info. I was simply suggesting the type of info we should look at? Since even the simple suggestion I made here might not be accepted by Ed, I just wanted to be sure we were not wasting time by looking at that data.

      ( I think I know what your are perhaps thinking at this moment, Yes, indeed, this strict Scientific Method is a bit slow for someone like yourself who, as an experienced scientist is quite capable of making "leaps of logic" in order to get to the core of an issue. But this is the procedure Ed insisted on and I have agreed to abide by it. We can nevertheless simultaneously continue our interesting side discussions – which I have enjoyed very much).

  6. Dr. Eric,

    In your post, you indicated you will pursue two hypotheses, each independent but with the second depending for its final input upon the outcome of the first. I accept this as a valid approach.

    How you continue with this will be your decision because you, after all, are ultimately responsible for proving your hypotheses.

    As for my advice, which I believe is in your interest, I suggest you initiate two new posts, for example:

    Hypothesis 1: Effect of Human CO2 Emissions on Atmospheric CO2
    Hypothesis 2: Effect of Atmospheric CO2 on Global Temperature

    Two posts will allow you to separate your efforts in each task and will help organize reader comments into these separate subjects. It will also allow you to move forward on both hypotheses in parallel if you wish. Granted, the final input to H2 will be the result of H1, you can still make significant progress on H2 even with tentative input data.

    I suggest you start a new post for each of the 3 separate steps, namely Formulation, Prediction, and Verification. However, ultimately, that is your decision. Fortunately, that decision need not be made now because your first task will be to defend your Formulation of each hypothesis. When you finish the Formulation task, you may decide it is better to open the Prediction discussion on a clean sheet.

    We both know the complications in each step in your hypothesis development and testing will be what you call #4, the other factors. These discussions may require more space than we may initially estimate, and may become the reason you will want to start a new post when you move to the Prediction phase.

    Regarding hypothesis formulation, I will be looking for the following criteria for an acceptable hypothesis:

    1. Can be described simply in one clear sentence (qualitatively).
    2. Can be described mathematically in sufficient detail to make predictions.
    3. Should be as simple as possible (Occam's Razor).
    4. Must be falsifiable.
    5. Should unify the cause and effect you are seeking.
    6. Should be comprehensive enough to embody the general hypothesis you will be trying to prove.
    7. Must be transparent enough to be understood and critiqued.
    8. Must be based upon empirical evidence.
    9. Must be consensus irrelevant.

    Independent from your efforts on your hypotheses, I will begin a Temperature Post and CO2 Post (following our discussions in Post #5) to contain and allow discussion of data that ultimately may be used by your hypotheses.

    If this sounds good to you, then let's move on.

  7. Allow me to embark on #4:
    " What other factors also effect global temperatures and must also be considered in answering question 3 above? "

    Correct answer to question #3 requires answering one major question: is sampling density of ground station grid adequate to resolve spatio-temporal variations of temperature field?

    More, no matter how paradoxical it sounds, even if all factors as global energy imbalance and global outgoing infrared radiation (OLR) are absolutely _constant_, the global average temperature [of a rotating globe] can drift in any direction, arbitrary, for several degrees C. It is therefore possible to construct various different zonal scenarios such that the "global temperature" is rising while global imbalance is in fact positive, or temperatures falling while the imbalance is negative, and planet is supposed to "warm up". In other words, "global average temperature" is not a proxy for warming, in climatismical speak.

    1. Cyril, this is very simple. It was observed (by truly yours) that some ground stations would exhibit long (~100y) downtrends in their records. Steven Mosher http://stevemosher.wordpress.com/2010/09/29/needs
      later looked at whole database, and found 513 stations with "negative warming" out of 1492 stations with 90+ years of records. My observation also was that there would be a station in close (50-60km) proximity of these stations with a warming trend. One conclusion is that spacing for ground stations does not seem to satisfy the Nyquist-Shannon-Kotelnikov-Whittaker sampling theorem for such complex spatio-temporal temperature field.

      The other deduction is that the planetary balance occurs in radiative domain, when parcels of surface emit as T^4, so the global average balance must be calculated as such, eventually, at the TOA. Omitting the sophistication of variational calculus, let me demonstrate the effect with the following example. Let the globe to have only two climate zones, say equatorial, and polar with equal surface area. Let the equatorial zone to cool a bit, while the polar zone warm faster (just as AGW "predicts"). Let the following table to be their time sequence, and global mean, all in absolute K:

      Equat Polar
      290 193.2 241.6
      289 196.4 242.7
      288 199.5 243.8
      287 202.5 244.7
      286 205.2 245.6
      285 207.9 246.4
      Trends:
      -5 +14.7 +4.9

      The time scale is arbitrary, for illustration purpose, but the temperature scale is close to reality.
      As you can see, one zone/station shows cooling, the other shows a bigger warming, but the "global average temperature" increases. What can we conclude from this observational record? It appears that nothing. The trick here is that every shown state has exactly the same "globally-averaged" OLR, 240.00W/m2 of outgoing longwave radiation. So, there is no cooling nor warming from any radiative imbalances in this example, yet the "global temperature" went up. Therefore, in a small range, there could be actual warming while temperatures go down, and opposite. It is easy to demonstrate all six permutations, and generalize the example for arbitrary number of zones or individual parcels of globe surface. So, when the globe is not uniform, there is an infinite number of configurations and trends that can occur without any global imbalance.

      So, pointing out to growing "global temperature" is pointless as an argument for AGW.

  8. Dr. Eric,
    I lack the credentials to be considered a climate physicist like Dr. Ed and yourself, however I am impressed by the quality of dialogue on this site and fascinated by the purpose of the debate. To assist novices like myself, I ask you to explain a remark you made in session 3 wherein, responding to my other post, you stated that you will rely on isotope data collected from glacial records and from the sea bottom. I understand how this data would enable you to chart historic temperature data going back hundreds of thousands of years, but since the debate is not about naturally occurring historical temperature fluctuations, but about the effect of the contribution by humans, how can the two contributors to isotope data be separated? The burning of carbonaceous materials by humans goes back 200-800 thousand years and we have continued burning forests to clear land for agriculture ever since.
    Please allow me to provide an example to illustrate my point. Suppose I collect tree ring data. The width of each ring can be affected by temperature and by available moisture. How can the contributions of each be separated so as to isolate the effect of moisture only on the growth of trees? If you manage to cross that hurdle, how then, can you distinguish between the effect of naturally occurring moisture on the tree ring growth and the effect of some human who waters the tree with a hose? Ergo, please explain how you can draw distinct conclusions from isotope data, i.e. the percentage contribution of sunlight and other natural factors from any human caused contribution through carbon emissions. The final hurdle, to use my example, is what contribution by man to the growth of a tree comes from a watering hose and what comes from an automatic lawn sprinkler. Applying this to human-caused global warming, how do you separate out the contributions to global warming from naturally released greenhouse gasses, from gasses released by cows, human respiration and burning of wood products and from that produced by the burning of fossil fuels? If you are going to win the debate, Dr. Eric, you are going to have to produce irrefutable data that makes these specific distinctions, i.e. prove that burning fossil fuels by man is overwhelmingly responsible for global surface temperature changes and not the other contributors.
    I am just an interested spectator who wishes to understand, the basis of the science you propose to use in defending climate change being mostly caused by humans burning of fossil fuels. Thank you.

    1. Johnmerlette,

      There are two ways to predict the future. One is by models based entirely on pure scientific understanding and theory. Another is by the study of what happened in the past. Usually both of these information sourced are used. That is why it is so important to understand what happened in the past and why it happened. You will see use these sources here. Because I am not a theorist, I am especially inclined to use historical observations for guidance concerning the future.

  9. William McClenney

    I apparently contracted pneumonia on a flight back from the east coast last week. So I am suffering with high fever and all the other symptoms. Lots of meds. So if I “lose the thread” occasionally, have patience.

    1. Has fossil fuel combustion increased during the Industrial Age of Man?
    2. Has the concentration of atmospheric CO2 increased during that period?
    3. How has the global average temperature changed during this period.
    4. What other factors also effect global temperatures and must also be considered in answering question 3 above?

    1. Unquestionably
    2. Unquestionably
    3-4. Although I could quote a litany of research in approaching the answer to this question, it dawned on my feverish mind that a very recent pre-publication Article in Press in the Journal of Geophysical Research would best serve the readership while also preserving what little energy I have at the moment.

    http://www.fel.duke.edu/%7Escafetta/pdf/scafetta-

    From the conclusions:

    “It is evident that we can still infer, by means of a detailed data analysis, that the solar system likely induces the climate oscillations, although the actual mechanisms that explain the observed climate oscillations are still unknown. If the true climate mechanisms were already known and well understood, the general circulation climate models would properly reproduce the climate oscillations. However, we found that this is not the case. For example, we showed that the GISS Model E fails to reproduce the climate oscillations at multiple time scales, including the large 60-year cycle. This failure is common to all climate models adopted by the IPCC (2007) as it is evident in their figures 9.5and SPM.5 that show the multi-model global average simulation of surface warming. This failure indicates that the models on which the IPCC’s claims are based are still incomplete and possibly flawed. The existence of a 60-year natural cycle in the climate system, which is clearly proven in multiple studies and herein in Figs.2, 6, 10 and 12, indicates that the AGWT promoted by the IPCC(2007), which claims that 100% of the global warming observed since1970 is anthropogenic, is erroneous. In fact, since 1970 a global warming of about 0.5C has been observed. However, from 1970 to 2000 the 60-year natural cycle was in its warming phase and has contributed no less than 0.3C of the observed 0.5C warming, as Fig. 10B shows. Thus, at least 60% of the observed warming since1970 has been naturally induced. This leaves less than 40% of the observed warming to human emissions. Consequently, the current climate models, by failing to simulate the observed quasi-60 year temperature cycle, have significantly overestimated the climate sensitivity to anthropogenic GHG emissions by likely a factor of three. Moreover, the upward trend observed in the temperature data since1900 may be partially due to land change use, uncorrected urban heat island effects (McKitrick and Michaels, 2007; McKitrick, 2010) and to the bi-secular and millennial solar cycles that reached their maxima during the last decades (Bond et al., 2001; Kerr, 2001; Eichler et al., 2009; Scafetta, 2010). Solomon et al.(2010) recently acknowledged that stratospheric water vapor, not just anthropogenic GHGs, is a very important climate driver of the decadal global surface climate change.”

    “Solomon et al. estimated that stratospheric water vapor has largely contributed both to the warming observed from 1980 to 2000 (by 30%) and to the slight cooling observed after 2000 (by25%). This study reinforces that climate change is more complex than just a response to added CO2 and a few other anthropogenic GHGs. The causes of stratospheric water vapor variation are not understood yet. Perhaps, stratospheric water vapor is driven by UV solar irradiance variations through ozone modulation, and works as a climate feedback to solar variation (Stuberetal., 2001). Thus, Solomon’s finding would partially support the findings of this paper and those of Scafetta andWest (2005, 2007) and Scafetta (2009). The latter studies found a significant natural and solar contribution to the warming from1970 to 2000 and to the cooling afterward.”

    “In conclusion, data analysis indicates that current general circulation climate models are missing fundamental mechanisms that have their physical origin and ultimate justification in astronomical phenomena, and in interplanetary and solar-planetary interaction physics.”

  10. 3. How has the global average temperature changed during this period.

    This is a very ill defined question and it doesn't bode well for a "scientific method" discussion.

    – What is global average temperature?
    – as we talk about averaging, is it space average? Time average? Both? Only for some altitude? Integrated over all or part of atmosphere? Integrated over all or part ocean? Only for some depth?
    – if it is a time average, over what interval? why this interval?
    – when one asks how this thing "has changed". Does it mean T(2000)-T(1900)?
    If yes why? If not what else?

    But most importantly why should such a contrived parameter that depends on at least 5 arbitrary definitions be interesting for anything?

  11. Tom Vonk, apparently you don't understand specifics of scientific method in climatology, as well in bio-psychopathology and pharmacology. Ask Adelady. We do not need stinking definitions, we are dealing with pieces of puzzle and trying to characterize them as best as we can, even if it is mathematically impossible. If a piece [of science] does not fit into current observational picture, we throw it away (temporarily), and move on.

    Regarding definitions from biggest climate scientists, please examine the following: http://data.giss.nasa.gov/gistemp/abs_temp.html

    A small excerpt:

    “Q. What do we mean by daily mean SAT ?
    A. Again, there is no universally accepted correct answer. Should we note the temperature every 6 hours and report the mean, should we do it every 2 hours, hourly, have a machine record it every second, or simply take the average of the highest and lowest temperature of the day ? On some days the various methods may lead to drastically different results.”

    Some people even can do triple-integral definitions: http://www.flickr.com/photos/81747157@N00/4890683
    Although the vertical coordinate of temperature field is missing in the above, it is a tiny insignificant detail, according to climate scientists above. Even if it can lead to "drastically different results" as climate scientist know.

    {sarcasm off}

  12. Dr.Eric wrote: "There are two ways to predict the future. One is by models based entirely on pure scientific understanding and theory. Another is by the study of what happened in the past. Usually both of these information sourced are used. That is why it is so important to understand what happened in the past and why it happened. You will see use these sources here. Because I am not a theorist, I am especially inclined to use historical observations for guidance concerning the future."

    This is a so wonderful position! Except one thing: what would you do if some very important data are not available?

    Let me illustrate. Climatology usually considers Earth albedo as constant, and "well known constant", which greatly simplifies things for going into past and future. However, it has been instrumentally observed http://www.iac.es/galeria/epalle/reprints/Palle_e
    that Earth albedo had an episode of 3% decline over about 10 years. This decline was correlated to decline in cloud cover from nearly 70% in 1986 to nearly 64% in 2000, according to ISCCP observations. This decline corresponds to radiative imbalance (aka "forcing") of about 10W/m2 in accord with direct planetary balance under the Sun. In other words, it corresponds to about 3 doubling of CO2, if we assume official forcing numbers, or "octupling" in CO2 concentrations. In other words, 6% change in cloud cover must have the same result as 800% change in CO2. This is a 100-fold factor, sensitively speaking.

    Now Dr. Eric, would you agree that an assumption of constant cloud/albedo would neglect a very substantial part of energy balance for the planet? If yes, then could you please provide cloud/albedo historical record (and accurate to 1%) for the past time intervals that are usually employed for model calibrations or demonstration of their hindcast skills? Satellite records for the last 10,000 years will suffice.

    As a side question: This forcing was unfolding right in front of all of us. Did you recall any climate effects of this effective 800% rise in CO2?

  13. Adelady @69: The title of article, "Can Earth's Albedo and Surface Temperatures Increase Together?" and the last paragraph in your quote clearly indicates that the authors try to adhere to the official AGW line that "global temperature is a proxy for warming". My example in post #57 http://climateclash.com/2010/10/21/4-prosecuting-
    illustrates that this conflation is not true, and therefore no special explanation is necessary for observed discrepancies – "global temperature" can go in either direction nearly independently from direction of radiative forcing, and there is no need to allude to possibility that "net radiative forcing" might be somehow substantially different. I'd like to thank you for bringing this up, because the Palle et al work can be interpreted as experimental confirmation of my thesis about free-walking global temperatures.

    I brought the Earthshine example to demonstrate that there are forces in climate dynamics that are 100-fold more powerful than the literally "borderline" effect of the CO2 absorption band. Yet nearly all models parametrize the effect of water evaporation-condensation-precipitation and constrain the amount of cloud cover to a constant, the value of which is frequently used to fix other energetic deficiencies as another free tune-up parameter.

  14. Thanks Al Tekhasski.

    Your comment is amusing but I mean my questions seriously.
    Consistent, logical and justified definitions are the necessary foundation of every argument that contains (even a bit of) mathematics.
    Without that it's just vague babbling in a pub.
    I came to this blog because I read that it was to be a "clash" of scientific arguments.
    I have a lot of them but before starting I need to be sure about definitions.
    Especially concerning a parameter that appears in every second sentence about the climate issues.

  15. I wonder if I might pose a question here?

    Past records show that CO2 levels lagged (atmospheric) temperature rise (and fall) by about 800 years on average.

    The way I understand AGW theory is that the additional CO2 will cause positive feedback and additional warming. My question is, are there any proxies that show this effect, or is it too small to measure?

  16. Leonard Weinstein

    Hans @41, I also agree that 3 is a critical point. It is also true that we can't answer that point conclusively. We only have a few years of reasonably complete data (satellite) and even that seems to be in some dispute. All the rest is at limited sites, over limited times, and of limited quality. Even if the recent temperature were a maximum over the holocene (which it almost certainly is not), or a maximum over the last 1000 years, which it may (but just by a small amount), that would not prove anything. The actual data, which is admittedly limited, indicates it it likely that the present peak is not even larger than the last 1000 years. (See http://www.co2science.org/ which has an extensive information base). I have some ice core and sea bed core data from the open literature going back over 2000 years that show at least for the polar regions and major sea beds, that the local temperature trend is a very small potato (see http://docs.google.com/Doc?id=dnc49xz_0fb228shr&a… ). These are not global, so are argued against. There is no global record, so where do we go next. I think we can agree that there has been some recent warming, and the CO2 has risen a lot, probably due to human activity. We then need to do the best we can to go from there.

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