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Climate Hustle

Does CO2 always correlate with temperature (and if not, why not?)

What the science says...

Select a level... Basic Intermediate

Surface temperature measurements are affected by short-term climate variability, and recent warming of deep oceans

Climate Myth...

There's no correlation between CO2 and temperature
"Twentieth century global warming did not start until 1910. By that time CO2 emissions had already risen from the expanded use of coal that had powered the industrial revolution, and emissions only increased slowly from 3.5gigatonnes in 1910 to under 4gigatonnes by the end of the Second World War. 

It was the post war industrialization that caused the rapid rise in global CO2 emissions, but by 1945 when this began, the Earth was already in a cooling phase that started around 1942 and continued until 1975. With 32 years of rapidly increasing global temperatures and only a minor increase in global CO2 emissions, followed by 33 years of slowly cooling global temperatures with rapid increases in global CO2 emissions, it was deceitful for the IPCC to make any claim that CO2 emissions were primarily responsible for observed 20th century global warming."
(Norm Kalmanovitch).

Why doesn’t the temperature rise at the same rate that CO2 increases?

The amount of CO2 is increasing all the time - we just passed a landmark 400 parts per million concentration of atmospheric CO2, up from around 280ppm before the industrial revolution. That’s a 42.8% increase.

A tiny amount of CO2 and other greenhouse gases, like methane and water vapour, keep the Earth’s surface 30°Celsius (54°F) warmer than it would be without them. We have added 42% more CO2 but that doesn't mean the temperature will go up by 42% too.

There are several reasons why. Doubling the amount of CO2 does not double the greenhouse effect. The way the climate reacts is also complex, and it is difficult to separate the effects of natural changes from man-made ones over short periods of time.

As the amount of man-made CO2 goes up, temperatures do not rise at the same rate. In fact, although estimates vary - climate sensitivity is a hot topic in climate science, if you’ll forgive the pun - the last IPCC report (AR4) described the likely range as between 2 and 4.5 degrees C, for double the amount of CO2 compared to pre-industrial levels.

So far, the average global temperature has gone up by about 0.8 degrees C (1.4 F).

"According to an ongoing temperature analysis conducted by scientists at NASA’s Goddard Institute for Space Studies (GISS)…the average global temperature on Earth has increased by about 0.8°Celsius (1.4°Fahrenheit) since 1880. Two-thirds of the warming has occurred since 1975, at a rate of roughly 0.15-0.20°C per decade."

Source: NASA Earth Observatory

The speed of the increase is worth noting too. Unfortunately, as this quote from NASA demonstrates, anthropogenic climate change is happening very quickly compared to changes that occurred in the past (text emboldened for emphasis):

"As the Earth moved out of ice ages over the past million years, the global temperature rose a total of 4 to 7 degrees Celsius over about 5,000 years. In the past century alone, the temperature has climbed 0.7 degrees Celsius, roughly ten times faster than the average rate of ice-age-recovery warming."

Source: NASA Earth Observatory

Small increases in temperature can be hard to measure over short periods, because they can be masked by natural variation. For example, cycles of warming and cooling in the oceans cause temperature changes, but they are hard to separate from small changes in temperature caused by CO2 emissions which occur at the same time.

Tiny particle emissions from burning coal or wood are also being researched, because they may be having a cooling effect. Scientists like to measure changes over long periods so that the effects of short natural variations can be distinguished from the effects of man-made CO2.

The rate of surface warming has slowed in the past decade. Yet the physical properties of CO2 and other greenhouse gases cannot change. The same energy they were re-radiating back to Earth during previous decades must be evident now, subject only to changes in the amount of energy arriving from the sun - and we know that has changed very little. But if that’s true, where is this heat going?

The answer is into the deep oceans. Here is a graphic showing where the heat is currently going:

 

The oceans absorb most of the heat from global warming 

From Nuccitelli et.al (2012)

The way heat moves in the deep oceans is not well understood. Improvements in measurement techniques have allowed scientists to more accurately gauge the amount of energy the oceans are absorbing.

The Earth’s climate is a complex system, acting in ways we can’t always predict. The energy that man-made CO2 is adding to the climate is not currently showing up as surface warming, because most of the heat is going into the oceans. Currently, the heat is moving downwards from the ocean surface to deeper waters. The surface gets cooler, humidity reduces (water vapour is a powerful greenhouse gas), and air temperatures go down.

The rate at which surface temperatures go up is not proportional to the rate of CO2 emissions, but to the total amount of atmospheric CO2 added since the start of the industrial revolution. Only by looking at long-term trends - 30 years is the standard period in climate science - can we measure surface temperature increases accurately, and distinguish them from short-term natural variation.

Basic rebuttal written by GPWayne


Update July 2015:

Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial

 

Last updated on 17 July 2015 by MichaelK. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Comments

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Comments 51 to 100 out of 180:

  1. Eclectic @50,
    I have at least two questions.
    1) How did they measure the aerosol density?
    2) If the aerosols were created by the industrialization and they counterbalanced the CO2 effect,
    how do you explain that the global temerature had been increasing from 1910 to 1940?
    See figure 1 of the following thread.
    http://www.skepticalscience.com/ivar-giaever-nobel-physicist-climate-pseudoscientist.html

  2. Ken Kimura @51 , it would be best if your questions about aerosols & other drivers of climate, were kept on the one thread i.e. "CO2 is not the only driver of climate".   That seems the most approriate thread; and it has the most approriate discussions in its comments column e.g. @20 and @21.

    Running the same/similar questions in parallel (in different threads) is not good policy on your part.   It gives the impression [ wrongly, I'm sure! ] that you may be more interested in "sloganeering" (as the moderators call it) . . . rather than in showing your genuine interest in finding information.

    Similarly, your comment in the above-mentioned thread, that [your quote:] "you know that the industrialization started long before 1940" . . . does suggest [ wrongly, I'm sure! ] that you think in binary terms of industrialization being entirely absent and then on a particular date, being suddenly present at a high level of activity.   Such comments by you, give the impression [ wrongly, I'm sure! ] that you prefer word games rather than science.

    Good luck with your search for information & wisdom.  There are some very knowledgeable people on this forum, who can help you.

  3. Eclectic @52,

    This thread and the other thread(and many others) are closely related.
    And many members post their opinions into these threads.
    So it is inevitable their opinions overlap.
    Hence, it is also inevitable that questions to them overlap.
    I don't see why asking similar questions to different members is discouraged.
    People have different opinions so that their answers may differ. Knowing different answers(some may be right, some may be wrong) is usually useful for most people.

  4. Ken @53 , there is something in what you say ~ yet you misunderstand the  basic Modus Operandi of this SkepticalScience website.

    When you ask a question or dispute a point, then your post will show in the Recent Comments page . . . where everyone will see it, and those who wish to reply will have the opportunity to go to your chosen thread. As a matter of course, the replies will also be funnelled through the Recent Comments page too.  This way everyone can see them conveniently, and those who wish to add to / correct / or dispute those replies, will be able to do so.

    So you see, that way you will get the best range of views / opinions / controversy / facts / useful links ~ all in the shortest time. And most conveniently all round.

    It is a sensible & efficient arrangement ~ which is why I recommended that you keep your particular cluster of questions in one thread only.  If you develop entirely unrelated questions as the discussion progresses . . . then it's best to get the first question(s) sorted out, before going on to another topic / another thread. It is best to progress step-by-step, reather than throwing up a large number of questions.

     ( Simultaneous multiple-pellet "shotgun" questioning is viewed poorly . . . since it's usually a sign of lack of sincerity in the poster ).

  5. If the signal of CO2 is obscured by other forcings, then it should be possible to calculate the effect of these other forcings and remove them. What remains should be the CO2 signal (plus the signal of whatever other forcings exist that we don't know about). Cowtan's presentation does something like that for the last 20 years or so, but he says nothing about the effect of the same forcings since, say, the turn of the last century (20th century). If the warmist theory is correct, the same forcings should have been in effect for this entire time and removing them should reveal the CO2 signal. At that point one would want to look for a steady upward trend from roughly 1900 to 2015, to match the steady upward trend in CO2 emissions. Has this ever been done? And if so, where can we find the result? Thank you.

    Response:

    [TD] Foster and Rahmstorf created such a graph for around 1980 to 2010 (maybe it's a bit longer period than that). The general topic is called "attribution" of warming. Other studies covering the period starting around 1950 have their results shown in a bar graph on that same SkS post. See also A Comprehensive Review of the Causes of Global Warming. For details, see in the IPCC's latest report, the chapter on attribution. Humans have had a significant influence from at least 1850 to the early 20th Century, a dominant influence from then until around 1950, and have caused all the warming since at least 1975 and possibly earlier.

    [TD] El Nino is removed from around 1955 through 2015, and also some other influences removed from 1970 through 2015, by Tamino.

  6. victorag @55, I recommend you run Kevin Cowtan's 2 box model in the default settings and look at figures 4, 5, and 6.  Unfortunately the data terminates with 2010, but the extra five years will make little difference.

  7. Yes, I'm very well aware of the Foster/Rahmstorf study. The problem is that it looks very much as though they carefully selected their forcings to provide the results they needed, and appear to have applied them to a time period also predetermined to give the desired results. While a great many forcings affecting climate over the last 120 years or so have been noted in various studies, they chose to include only three, over a period of only 30 years or so. The implication is that if they included more than the carefully selected three they would not have gotten their desired result.

    The only way to conduct a scientifically viable test of CO2-temp. correlation would be by systematically eliminating ALL the forcings identified over the entire period in question, i.e. at least the beginning of the 20th century. 

    Now if you want toclaim that CO2 is responsible for all the warming since 1975, that's a totally different matter. Are you implying that there was some sort of tipping point reached at that time, prior to which the effects of CO2 emissions were negligible? If that's the case then it would not be proper to talk about a long-term warming trend due to CO2, would it? In that case you'd be talking about a period of 25 years when temperature did in fact shoot up in tandem with CO2 emissions. But after those 25 years, the temp. increase slowed while CO2 continued to soar. How do you account for that?

    I see no alternative other than the elimination or "attribution" study I suggested, where ALL forcings are taken into consideration over the entire period in question. As it seems to me such studies so far have been conducted on a piecemeal rather than comprehensive basis.

    Response:

    [TD] All data and code for Foster and Rahmstorf (2011) are public, so you are free to scrutinize those and run the code yourself. You are also free to modify and run their code with additional forcing data. The links I provided describe multiple other studies that you have ignored. Please read those before claiming that they do not exist. For a very thorough review, read the IPCC's AR5 Chapter 10 on Attribution.

     

     

  8. Tom Curtis @56. Thanks for the link. Cowtan has been providing some very useful services at his websites, I must say. I find this one very interesting, but it has me puzzled. We are expected to provide a weight for each forcing, but how could one be expected to know that without being able to quantify the effects of each, and on a year by year basis. For example, the weighting for volcanic aerosols would be different from year to year, depending on volcanic activity during each year. And one would have to have access to some very reliable studies in which such year by year effects are measured. And the measurements would have to be made compatible somehow with similar year by year measurements for all the other forcings. His results seem to depend on an equal weighting for each forcing for every year, which makes no sense.

    What am I missing?

  9. I must add that I find Cowtan's graphs fascinating. Is there a paper that goes with them?

  10. victorag, your logic behind your cherrypicking claim about Foster and Rahmstorf is invalid. The goal of Foster and Rahmstorf was to remove the influences of non-CO2 factors, to better reveal the effect of CO2. That is a straightforward procedure and logically airtight. Your claim that removing other factors somehow would hide rather than reveal CO2's effect is nonsense.

  11. Victorag - See the numerous attribution studies listed here. As to your yearly variations issue, that's a matter of measuring the forcings and applying them with either a derived (attribution study) or best estimate (projections) of their efficacies. There is extensive literature detailing estimated forcing levels, see the information on the GISS model forcings here

    Incidentally, the use of the term "warmist" on your part leads to the perception that you frequent denial sites, and aren't really looking for the science - just so you know. 

  12. Thanks for the advise, KR. But I am at a loss to find a term characterizing those I've referred to as "warmists." I'm tempted to use "alarmists" but that's much worse, no? What would you suggest?

    Response:

    [PS] Lets not get offtopic with fights over labels. And in particular I would remind all parties to avoid provocative labelling. Victor I would note that "warmist" in your use would "climate scientist".

  13. #60 No, it looks to me, Tom, as though Grant and Rahmstorf were doing the cherrypicking. What cherries do you think I picked?

    Response:

    [PS] Tom does not accuse you of cherry-picking. He disputes your logic by pointing out what the study sought to achieve and as such used the data available for that purpose. To continue, please state which forcings you think are missing. I would also note that a similar statistical approach was used by Benestad and Schmidt 2009 with full forcing set. That paper points out the limitations on a statistical approach as well and I would suggest a look at the larger literature on attribution as other commentators have suggested.

    I would also note that taking the non-statistical approach - directly account for forcing - is what models do and you have runs covering centuries as well as studies on say ice terminatation or initiation. However, such approaches do not directly reveal CO2 influence on simple graph but as a climate sensitivity number.

  14. victorag @58, in Kevin Cowtan's model, the year to year change in radiative forcing for each component is provided by estimates of the historical values.  You can use one of two estimates, the default Meinhausen (2011) estimates, or those GISS (2011).  If you leave all weightings at 1 and look at figure 3 (scaled forcings) you will see they vary year by year.  What the weightings allow you to do is adjust the relative strength of the forcings if you think one or more of those forcings have been significantly under or over estimated, or if you think the impact of one or more of the forcings significantly differs from what you would expect from their radiative forcing.  To take a common "skeptical" line of thought, for example, if you think the effect of WMGHG and aerosols are one tenth of that which we would estimate by radiative forcing alone, and that the solar forcing has been underestimated, we could adjust the former three (WMGHG, aerosol direct and aerosol indirect effects) to 0.2 and the latter to 2.  Doing so, however, drops the coefficient of determination from 0.932 to 0.807 (and does worse things to the RMSE, although the model does not directly calculate that).  That suggests that this popular 'skeptical' theory does appreciably worse at explaining the 20th century warming than does the standard IPCC account, in addition to facing significant theoretical difficulties.

    As I understand it, the default (2 box) variant of Kevin Cowtan's model is a variation of that described in section 3 of Cawley et al (2015).  The only significant difference as I understand it is that the model in Cawley et al uses only one time constant which makes it closer to the 1 box variant.  A more complete explanation of the model as presented can be found in the Skeptical Science online course which started on Aug 9th.

  15. victorag @57, the Foster and Rahmstorf paper uses a time period of 1979 to 2010 because the satellite temperature records start in 1979 and the paper was published in 2011 (and hence had no later data).  It is difficult to describe using the full period of overlap of the temperature series they used available to them, as they did, as cherry picking with respect to time.  It is possible to adopt the same approach as that in the paper over a more extended period, but the cost of so doing is that you must exclude the satellite datasets.

    The three variables controlled for in the Foster and Rahmstorf model are the two known natural forcings plus the major component of natural variability.  The resulting adjusted temperature therefore reflects not the temperature influence of CO2, but of the sum of all anthropogenic forcings.  It may interest you to note than in discussions on his blog, Grant Foster indicated that he had tried variations of his model which also adjusted for the Pacific Decadal Oscilation and the (from memory) the Atlantic Multidecadal Oscilation and found that they had no appreciable impact (but also that you could use the PDO instead of ENSO with no appreciable impact).  It is possible that the AMO was near linear over the time period dictated to Foster and Rahmstorf by their data, in which case the adjusted temperature series also includes an AMO component, but that does not sit well with measured values of the AMO:

    Alternatively, you could argue that variations in the AMO closely mirror those of ENSO, and that as a consequence the ENSO adjustment in the Foster and Rahmstorf model incorporates an AMO signal into its ENSO adjustment.  That being the case, the adjusted temperature series still represents the influence of the sum of anthropogenic forcings.

    Finally, you could argue that there is a significant natural forcing in addition to the solar and volcanic forcing and which is not a linear function of either.  In that case, the impacts of that natural forcing would also be included adjusted temperature.  However, to my knowledge, no such natural forcing has been identified, and certainly no such natural forcing has been identified by the IPCC in any of their assessment reports - so Foster and Rahmstorf cannot be faulted for neglecting this purely hypothetical possibility.

    Given all of this, I can see no basis for your accusation of cherry picking against Foster and Rahmstorf. 

  16. To Tom and others responding to my posts: thank you very much for your thorough commentaries, which I find very interesting and helpful. I'll need some time to consider them and will need to do a bit more reading and thinking before offering a reponse, maybe some time tomorrow.

  17. OK, I'm back. First off I want to clarify by stressing that it was not my intention to accuse Foster and Rahmstorf of conscious deception. I have no reason to believe they were being anything other than sincere. Also, the impression I have that they were cherry picking might well be unfair. I'm not a climate scientist so it's possible there are things in their paper I do not understand.

    Nevertheless it's very hard to discount the impression of cherry picking, because after all there are many more natural forcings than the three they selected, and one therefore can't help but wonder whether they were selected simply because they produced the desired result. And one also can't help wondering whether the paper would have been published at all if some other result had emerged.

    While the detailed explanation very graciously provided by Tom might be perfectly valid, that does not alter the perception that confirmation bias could be at work, however unconsciously. My reaction, right or wrong, when I first read the paper was that 1. I questioned the choice of those three forcings as they appeared to be cherry picked; 2. even if we assume they were not cherry picked, one still can't help but wonder whether these same three forcings were all that were needed to correct for other discrepancies in the temperature data over a much longer time period, such as the 1940-1979 "hiatus" — and if they are not sufficient for this earlier period, why would they be sufficient for the period covered by the FR paper?

    I am also wondering whether there has been any followup to the FR paper, and whether the three criteria they chose in 2010 still do the same job as convincingly when we consider the intervening years from then to now?

  18. [PS] "Tom does not accuse you of cherry-picking. He disputes your logic by pointing out what the study sought to achieve and as such used the data available for that purpose. To continue, please state which forcings you think are missing."

    I was thinking of the presentation offered on this blog by John Cook back in 2009, titled The CO2/Temperature correlation over the 20th Century ( http://www.skepticalscience.com/The-CO2-Temperature-correlation-over-the-20th-Century.html ), in which he lists 10 such forcings. It seems to me that if you are going to systematically analyze the effects of natural forcings you need to settle on the exact number of all forcings that have been identified and then apply them across the board. If certain ones have no appreciable effect during a certain period that's no excuse for excluding them — unless you want to open yourself to the perception of cherry picking. I'll add, by the way, that after all natural forcings have been identified and removed, that does not necessarily leave you with CO2, because the remainder might well be some as yet unidentified forcing, combined with CO2.

    The paper by Benestad and Schmidt to which you refer is about solar forcings and, as I recall, the effect they found of solar forcings during the sharp warmup of1910-1940 is only slight. I've seen others claim that this warming period could be explained by solar forcing, but this study would seem to have refuted that theory. If in fact there is still no natural explanation for the early 20 century warmup, and CO2 levels were too low to have much effect, then it looks as though there is some as yet unidentified natural forcing that produced the warming during that period — and the same natural effect could have caused the similar extreme warmup during the period 1979-1998.

    The cooling from 1940 onward, followed by a long levelling off until 1979 is also difficult to explain as the result of natural forcings, despite Cook's effort to do so. After reading through the paper by Hansen et al, on which he bases his data, the many complexities and uncertainties in the assessment of these various forcings become all too evident.

    Response:

    [PS] Was it that hard to just click on the Benestad and Schmidt ref? It uses all the forcings. Also note in the your Cook link that forcing are not equal and most are very minor.

    The claim "The cooling from 1940 onward, followed by a long levelling off until 1979 is also difficult to explain as the result of natural forcings, despite Cook's effort to do so." verges on sloganeering if you do not provide evidence to support that, and aerosols are an anthropogenic forcing.

  19. victorag wrote:

    It seems to me that if you are going to systematically analyze the effects of natural forcings you need to settle on the exact number of all forcings that have been identified and then apply them across the board. If certain ones have no appreciable effect during a certain period that's no excuse for excluding them — unless you want to open yourself to the perception of cherry picking.

    victorag is sloganeering, because he has failed to respond or even acknowledge my previous response in which I pointed out that "cherrypicking" is logically impossible as a label for removing only a subset of factors, when the goal of those authors was to eliminate the influence of that particular subset of factors in order to better reveal the influences of all the remaining factors. VictorAG continues to baselessly and totally irrationally claim that by eliminating only some factors it is possible to hide the influence of the remaining factors.

  20. victorag @67 & 68:

    1)


    "one still can't help but wonder whether these same three forcings were all that were needed to correct for other discrepancies in the temperature data over a much longer time period, such as the 1940-1979 "hiatus""


    Except that if you look at Kevin Cowtan's model on the default settings, you can see that those same factors account for the 1940-1979 hiatus (Fig 1).  You can also see that the response to volcanic forcings is the major natural player in the temperature increase from 1910-1940 (Fig 4), and that ENSO is a major player in flattening the temperature response in the 1940-1979 hiatus (Fig 5).

    It should be noted that Cowtan's model uses the same two natural forcings, plus the same mode of natural variability as is used in Foster and Rahmstorf.  Further, instead of a default assumption that any temperature response not due to those three factors is due to the sum of anthropogenic forcings, it explicitly includes those anthropogenic forcings.  If a Foster and Rahmstorf's methodology would not reproduce the anthropogenic temperature response if applied over the full 1880-2010 interval, then neither should Kevin Cowtan's model produce such a good fit over that interval using the same modes of natural influence plus the explicit anthropogenic forcings.     

    2)


    "I am also wondering whether there has been any followup to the FR paper, and whether the three criteria they chose in 2010 still do the same job as convincingly when we consider the intervening years from then to now?"


    Here is are the results of the Foster and Rahmstorf adjustment updated to 2012:

    For what it is worth, 2011 and 2012 saw the two strongest La Nina years since 1974/75.  Since then we have had two neutral years (2014 and 2015) each of which set temperature records unadjusted, and an El Nino year which has seen unprecedented montly temperatures in the first half of the year, and is very likely to set a third annual, global record temperature in a row.  Given that, it is likely that the Foster and Rahmstorf methodolog would indeed do the same job as convincingly, although I can find no update to 2015.  I can, however, find an ENSO only adjustment to 2015 which supports that contention:

    3)


    "I was thinking of the presentation offered on this blog by John Cook back in 2009, titled The CO2/Temperature correlation over the 20th Century ( http://www.skepticalscience.com/The-CO2-Temperature-correlation-over-the-20th-Century.html ), in which he lists 10 such forcings. It seems to me that if you are going to systematically analyze the effects of natural forcings you need to settle on the exact number of all forcings that have been identified and then apply them across the board."


    Of the ten forcings identified by John Cook, only two are natural - solar and volcanic.  The ten forcings are the same forcings as used in Kevin Cowtan's model, and if you set the model to the GISS 2011 forcings, you can even use the same dataset (extended by two years) as is used in John Cook's article.  So, again "The resulting adjusted temperature [in the Foster and Rahmstorf model] therefore reflects not the temperature influence of CO2, but of the sum of all anthropogenic forcings" (see my comment @65); and again Foster and Rahmstorf use the same natural causes of variability as those used in Kevin Cowtan's model (with all 10 explicit forcings) with essentially the same result over the 1979-2010 interval (see Fig 6 of model results).

    As to any unknown forcings, first in science a principle of economy is applied where we do not postulate causes without reason do do so.  Foster and Rahmstorf (and Kevin Cowtan's) model show that the temperature data do not require us to postulate additional causes for the global temperature variation.  Therefore if you want to postulate an additional natural source of variability, you need to show why it is necessary.  You also need to provide (or find where somebody has provided) an annual index of that purported cause of variability without which the effect of the purported cause of variability cannot be tested (ie, the claim that it is a cause of variability has not been put in a falsifiable form).  It is not incumbent on working scientists to chase every 'fairy at the bottom of the garden theory', but rather of the proponents of those theories to bring them into sufficiently rigorous a form that they can be tested by scientists.

    Further, given the efficacy of the explanation of global temperature from 1880 onwards using the two natural, eight anthropogenic forcings plus ENSO, any postulated additional natural cause of variability must be highly correlated with one of the two natural forcing, the anthropogenic forcing, or ENSO.  That would be astonishing if coincidental, and if not coincidental then the purported additional natural cause of variability has already been included de facto in the analysis.  Further, if its correlation was with an anthropogenic forcing and the correlation was not coincidental, the purported additional cause would also be anthropogenic.

    Response:

    [PS] Thanks Tom for your considered and civil response. Victor, in the interests of maintaining civil and focused dialogue, it would be could if you could indicate where you agree or disagree with response made to you. It would especially be appreciated if you refraimed from shifting the goalposts.

  21. Once again I want to thank everyone who responded for being so patient, so thorough and so civil. I hadn't noticed that I'd shifted the goalposts, but if that's the case I apologize. I find this dialogue extremely interesting and useful but I hope no one will mind if I persist a bit with some further questions. What I hope you will all consider is not simply the issues I've raised per se, but how questions such as these might help you to understand why some of us have remained skeptical for so long. It's not so much that I claim to understand what climate scientists are doing and reject it, as that I do not understand completely and that certain disturbing questions persist, probably because the matter at hand is so complex, but also because certain technical issues go over the heads of laymen struggling to understand. I won't attempt to deal with all the issues that have been raised, but I do have a few more questions/comments:

    1. I did click on the Benestad and Schmidt paper and read much of it. I realize that many forcings were considered but what got my attention was the graph illustrating, in part, the affects of solar forcings during the early 20th century, and it looks to me as though the slope is too narrow to account for the steep temperature rise. Tom C. has claimed, above, that the response to volcanic forcings is the major factor, based on Cowtan's graphs. This is a perfect example of the sort of thing skeptics such as myself have problems with, because it's hard to see how the lack of a forcing could produce a significant warming. It seems more logical to posit some unknown forcing that could have produced this effect. And if you want to insist that there is no evidence of such a thing, my answer would be that this very dramatic runup in warming seems to be the evidence.

    Secondly, I don't see how a set of graphs can in itself demonstrate anything in the absence of some sort of report explaining what they represent and how they were arrived at. Has Cowtan published on this and if so could you provide a link.

    2. "The claim "The cooling from 1940 onward, followed by a long levelling off until 1979 is also difficult to explain as the result of natural forcings, despite Cook's effort to do so." verges on sloganeering if you do not provide evidence to support that, and aerosols are an anthropogenic forcing."

    Where is this term "sloganeering" coming from? I don't recall offering a slogan. Have you consulted a dictionary? And yes, I can provide such evidence, in the form of a paper by James Hansen et al., published in the journal Climate Dynamics, in 2007: "Climate simulations for 1880–2003 with GISS modelE." (This was available on the Internet but as I just discovered, it no longer seems to be. Perhaps you already have a copy.) The data in this paper was the basis for the data used by Cook in his aforementioned blog post. Here is an excerpt from the abstract: 


    We carry out climate simulations for 1880–2003 with GISS modelE driven by ten measured or estimated climate forcings. . . Discrepancies between observations and simulations with all forcings are due to model deficiencies, inaccurate or incomplete forcings, and imperfect observations. Although there are notable discrepancies between model and observations, the fidelity is sufficient to encourage use of the model for simulations of future climate change. . . Principal model deficiencies include unrealistically weak tropical El Nino-like variability and a poor distribution of sea ice, with too much sea ice in the Northern Hemisphere and too little in the Southern Hemisphere. . .


    The paper, written with the assistance of 38 associates, is incredibly complex and, as the author himself acknowledges, filled with "notable discrepancies" and "deficiences," and, judging from the content generally, many uncertainties. Yet Cook picks up on data and graphs from this paper and refers to them as though they constituted reliable evidence that CO2 is "the dominant forcing" and that this data is sufficient to establish the correlation in question, i.e. the correlation between CO2 emissions and global warming. Sorry, but after skimming through the complexities of the Hansen paper, I find this pat conclusion difficult to accept.

    I have one other point to make but I'll do that in a separate post.

    Response:

    [PS] Just to be clear: Sloganeering in my interpretation is making an assertion (the slogan) without providing supporting evidence.

    When Tom answered your criticism on F&R, you suddenly jumped to another objection which is suspiciously like shifting the goal posts. A published to reference to Cowtan's works has already been given (Crawley et al).

  22. Speaking very generally:

    I've done a fair amount of research in the social sciences, especially in the areas of semiotics, ethnology, and cultural evolution, and have read extensively in the fields of psychology, archaeology, population genetics and cognitive science. And one issue that keeps coming up whenever data is being evaluated, is the issue of bias. As is well recognized in all the sciences, researchers tend to see what they expect to see, or what they want to see, and as a result many studies are tinged by confirmation bias, regardless of the intentions of the researcher, which are usually honorable.

    As a result, in many fields the gold standard for any sort of testing is the controlled, double-blind experiment, where no one involved in the process has any knowledge of what's involved or any interest in the result. I realize, of course, that double-blind research is usually not possible in a field such as climate science, but that does not mean that the possibility of bias should be ignored. There is a very good reason why double-blind testing is considered so important.

    I've read a great many papers by obviously qualified climate scientists that deal with the issue I've raised here, i.e., the correlation or lack of it between CO2 and warming, and while there is certainly much that I'm incapable of understanding, the impression I get is that the goal of the research in almost every case is to find some way to justify a predordained result. Thus if it's a question, say, of "accounting for" something like the so-called "hiatus," then the entire research effort is directed toward that goal, and if the goal cannot be reached then the research would be deemed pointless and would remain unpublished.

    This is the impression I got from the Grant/Rahmstorf paper especially, but I get similar "vibes" from many of the others as well. While this feeling might in fact be unjustified, I do believe it goes a long way toward explaining the skepticism of so many when encountering this research, because in the absense of something like a controlled double-blind experiment it's very difficult to completely remove the suspicion of confirmation bias, even if it isn't there. It would be helpful, I think, if someone were to lobby for a different approach, where the interpretation of the data could be done by people from some other field, with no skin in the game and no preconceptions — or at least double checked by such people on a completely independent basis, so there is no possibility of influence from the primary researcher to what we could call the "control group."

    When we see result after result that appears to confirm the same hypothesis, then many climate scientists see that as proof positive that "climate change is real." But a skeptic such as myself can get a very different impression, for the reasons summarized above. Rather than continually harping on the "mounds of evidence" supporting your position, which only arouse suspicions, you might do better to find some way to convince the world that your findings are the result of truly impartial and objective research rather than simply a set of foregone conclusions.

    Forgive me if my remarks seem offensive, but imo these are issues you need to consider if you expect the entire world to bend to your demands.

    Response:

    [PS] Claims of "bending to demands" is incendary. Repeat similar and post will be deleted. It is not deleted so that other commentators are able to judge your so called serious enquiry.

    If you cant fault the science demonstating the correlation when done properly, you cannot dismiss it with hand-wavy comments about how you believe science should be done. If this is wrong, then where are the alternative skeptic theories that provide better explanation?

    Instead of the handwaving, once again, please state to commentators where you agree and where you disagree.

  23. Speaking very generally:

    I've done a fair amount of research in the social sciences, especially in the areas of semiotics, ethnology, and cultural evolution, and have read extensively in the fields of psychology, archaeology, population genetics and cognitive science. And one issue that keeps coming up whenever data is being evaluated, is the issue of bias. As is well recognized in all the sciences, researchers tend to see what they expect to see, or what they want to see, and as a result many studies are tinged by confirmation bias, regardless of the intentions of the researcher, which are usually honorable.

    As a result, in many fields the gold standard for any sort of testing is the controlled, double-blind experiment, where no one involved in the process has any knowledge of what's involved or any interest in the result. I realize, of course, that double-blind research is usually not possible in a field such as climate science, but that does not mean that the possibility of bias should be ignored. There is a very good reason why double-blind testing is considered so important.

    I've read a great many papers by obviously qualified climate scientists that deal with the issue I've raised here, i.e., the correlation or lack of it between CO2 and warming, and while there is certainly much that I'm incapable of understanding, the impression I get is that the goal of the research in almost every case is to find some way to justify a predordained result. Thus if it's a question, say, of "accounting for" something like the so-called "hiatus," then the entire research effort is directed toward that goal, and if the goal cannot be reached then the research would be deemed pointless and would remain unpublished.

    This is the impression I got from the Grant/Rahmstorf paper especially, but I get similar "vibes" from many of the others as well. While this feeling might in fact be unjustified, I do believe it goes a long way toward explaining the skepticism of so many when encountering this research, because in the absense of something like a controlled double-blind experiment it's very difficult to completely remove the suspicion of confirmation bias, even if it isn't there. It would be helpful, I think, if someone were to lobby for a different approach, where the interpretation of the data could be done by people from some other field, with no skin in the game and no preconceptions — or at least double checked by such people on a completely independent basis, so there is no possibility of influence from the primary researcher to what we could call the "control group."

    When we see result after result that appears to confirm the same hypothesis, then many climate scientists see that as proof positive that "climate change is real." But a skeptic such as myself can get a very different impression, for the reasons summarized above. Rather than continually harping on the "mounds of evidence" supporting your position, which only arouse suspicions, you might do better to find some way to convince the world that your findings are the result of truly impartial and objective research rather than simply a set of foregone conclusions.

    Forgive me if my remarks seem offensive, but imo these are issues you need to consider if you expect the entire world to bend to your demands.

    Response:

    [JH] Argumentative & hyperbolic sloganeering snipped. 

  24. Hrmmm . . . yes, Victor.  I have an idea.  How about we get roughly 300 of the leading climate scientists together and have them work over the basic science.  They'll end up creating a summary based on the existing research.  Then, they can open up their summary to a series of peer reviews.  Maybe two of them should be open reviews.  I expect several thousand scientists would want to get involved in review.  If the basic science made it out of that process still established as the overwhelmingly consensus-of-evidence strongest theory, would you elevate your level of probability for it?

  25. "Instead of the handwaving, once again, please state to commentators where you agree and where you disagree."

    I agree that the attribution of "global warming" to a variety of different forcings makes sense. I agree that such attributions involve all sorts of complexities. And I agree that climate scientists are uniquely qualified to research these complexities.

    I do not agree that the picture is sufficiently clear for anyone to claim that any single forcing is a decisive factor influencing world climate. And I do not agree that simply by attempting to account for certain discrepancies by estimating the influence of specific forcings is in itself sufficient to produce a correlation between any one forcing (such as CO2) and temperature. Nor do I agree that selecting one set of forcings to account for a discrepancy during one historical period and another set when dealing with another period (as we find when we compare Grant/Rahmstorf's paper with Cook's blog post) is a valid procedure.

    I also do not agree that the long list of papers intended to "account for" what looks on the surface like a lack of correlation is sufficient to produce such a correlation nevertheless. It's an open question whether each paper reinforces the previous ones or can better be seen as an attempt to correct their inadequacies. The recent paper by Karl et al. would appear to render all these older studies obsolete in any case.

    More specifically, I cannot agree that any known forcings, including CO2, are capable of accounting for the dramatic temperature rise we see from 1910 to 1940. I find it difficult to accept that a rise of this magnitude could have been caused largely by the absence of volcanic activity. That strikes me as absurd. Nor can I accept that the grab bag of forcings offered by Cook can account for the cooling and leveling off we see from 1940 through the late Seventies. If CO2 emissions are a major factor in global warming then it's reasonable to assume that the signal of a steady rise in CO2 emissions during that period would be apparent in the temperature data — but no such signal is apparent, during a period of roughly 40 years.

    All I can think of for now.

    Response:

    [PS] Thank you

  26. Victor

    Just some things to consider, re the 1910-40 period.

    1. This is just atmospheric changes. We don't know what was happening in the oceans - no meaningful data. So we can't rule out an atmosphere/ocean heat transfer producing that change. Not a change to the total system but a small movement of energy from the dog to it's tail. In contrast, we know what is happening in the oceans as well today. This isn't just a transfer between the dog and the tail. They are all warming.
    2. 1910-1940 included some important other changes. Temperature station coverage in the high northern hemisphere was only developing during this period, particularly in the Soviet Union. We don't know whether some of this was an artefact of sensor coverage. The 1940's included some important changes in how sea surface temperatures were measured during the war years. What was the impact of this?
  27. Victor Grauer @75.

    You say "I cannot agree that any known forcings, including CO2, are capable of accounting for the dramatic temperature rise we see from 1910 to 1940."

    As calculated by IPCC AR5, the "known forcings" of human origin for 1940 total 32% of the "known forcings" of human origin for 2011 (the final data in the IPCC assessment). These forcings rise over the 40 years preceeding 1940 roughly proportionately to the 40 year rise preceeding 2011 suggesting a comparison with the resulting global temperature rise above 'pre-industrial' would not be ill-advised. The result of the "dramatic temperature rise,"the 1938-42 temperature (using HadCRUT4) relative to 1850-1900, is 38% of the 2009-13 temperature relative to 1850-1900.

    Why do you consider this less-than-dramatic difference between 32% of forcing and 38% of ΔTemp to be the subject of such controversy? Do you assess "the dramatic temperature rise" in some other way?

  28. #76 Glenn Tamblyn

    Since I'm not a climate scientist I can't properly evaluate your analysis, but I see no reason to doubt it. However, an explanaton, based on uncertainties as to what might have produced the early 20th century runup is hardly evidence supporting the notion that a correlation between CO2 emissions and global warming has been identified.

    #77 MA Rodger   

    Again, since I'm not a climate scientist I am not in a position to dispute your numbers. However, from what I read in the literature it seems as though most researchers do not see CO2 emissions as a significant contributor to the warmup during this period. Correct me if I'm wrong.

  29. @Victor,

     You said, "correct me if I am wrong". You have been corrected multiple times, and even stated flatly, "since I'm not a climate scientist I am not in a position to dispute your numbers"

    If you can't dispute the numbers from the climate scientists trying to correct you from being wrong, then I see no reason for you to keep cluttering this forum with your unsupported denialism. 

    Maybe come back when you do have some supporting evidence?

  30. Sorry about missing the earlier reference to Cawley et al. I printed it out last night, and read it this morning. Judging from the discussion on p. 5, and the very intesting graphs presented in their Figure 3, it does look like they've carried out more or less the same sort of program I suggested back in post 55. Figure 3b does indeed seem to display a correlation of precisely the type on which I was insisting, in which all forcings other than CO2 have been subtracted, so we could get a clearer look at whether a correlation with temperature actually exists — and it looks very much as though it does. Of course, as I indicated earlier, the residue presented in such a graph doesn't necessary represent CO2, as some other, unknown, forcing could be at work. 

    Regardless of such considerations, however, their model is hedged with some serious caveats:

    . . . both models are potentially susceptible to omitted variable
    bias. . . 

    The model presented here has the opposite bias, in that it attributes to internal climate variability what cannot be explained by the forcings (or ENSO in this case). As a result, a model of this type should not be
    used to uncritically argue that climate sensitivity is high . . .

    Attributing climate change to natural and anthropogenic causes cannot be performed reliably using such a naıve correlative model, as the conclusions are so heavily dependent on the modelling assumptions.

    One wonders whether this last sentence might have been a requirement stemming from peer review. In any case, the honesty is very much appreciated. And the difficulty in producing the desired result is made clear, since so much depends on the existence of prior assumptions, of which the investigators may or may not be fully aware. 

  31. Victor Grauer @78.

    You seek correction if you are wrong.

    You infer that you would like to 'dispute my numbers' but say you are unable because 'you're not a climate scientist'. You are incorrect. The data I use is readily available for use by any layman armed with a spreadsheet, both HadCRUT4 and IPCC historic ERF. I didn't see the point of providing web links @77 as use of these datasets here @SkS is so run-of-the-mill.

    Even without a spreadsheet, a pre-industrial global temperature could be readily estimated from a graph of HadCRUT4 and the IPCC forcings totted up. With a 1940 total anthropogenic ERF of 0.613Wm^-2, a climate sensitivity (TCR) of 2ºC, a warming of something like +0.33ºC could be inferred which is pretty-much what HadCRUT4 shows for 1940.

    These numbers may be subject to correction; poor eyesight or fat finger syndrome always makes error possible. But you are incorrect inferring that these numbers can be "disputed".

    Of course, this represents a trivially simple assessment but shows quite well that the these ERF (of which CO2 is the largest contributor) indeed "are capable of accounting for the dramatic temperature rise we see from 1910 to 1940" and thus your assertion @75 is incorrect.

    You are correct @78 to consider that the task of attributing the warming of the early 20th century does rattle round the literature. Serious climate models do not deliver the levels of anthropogenic warming suggested by the simple calculations above. But while literature may debate the role of internal variability & natural forcings, you assert @78 that "researchers do not see CO2 emissions as a significant contributor to the warmup during this period." Anthropogenic forcings (of which CO2 is the largest contributor) remain "significant contributor" within such studies although they are probably not the overwhelming factor in that period. As the IPCC AR5 (this the "review" DSL @74 was likely alluding to) concludes on the matter:-

    "...the early 20th century warming is very unlikely to be due to internal variability alone. It remains difficult to quantify the contribution to this warming from internal variability, natural forcing and anthropogenic forcing, due to forcing and response uncertainties and incomplete observational coverage." (My bold)

    Thus your assertion @78 is also incorrect.

  32. #81

    Before 1940, the increase in temperature is believed to have been caused mainly by two factors:

    Increasing solar activity; and
    Low volcanic activity (as eruptions can have a cooling effect by blocking out the sun).

    Other factors, including greenhouse gases, also contributed to the warming and regional factors played a significant role in increasing temperatures in some regions, most notably changes in ocean currents which led to warmer-than-average sea temperatures in the North Atlantic. (https://www.skepticalscience.com/global-warming-early-20th-century.htm)

    From http://www.nature.com/ngeo/journal/v8/n2/full/ngeo2321.html :

    Of the rise in global atmospheric temperature over the past century, nearly 30% occurred between 1910 and 1940 when anthropogenic forcings were relatively weak.

    From http://onlinelibrary.wiley.com/doi/10.1029/2005GL023540/abstract :

    We analyze surface air temperature datasets simulated by a coupled climate model forced with different external forcings, to diagnose the relative importance of these forcings to the observed warming in the early 20th century. The geographical distribution of linear temperature trends in the simulations forced only by natural contributions (volcanic eruptions and solar variability) shows better agreement with observed trends than that does the simulations forced only by well-mixed greenhouse gases. Using an optimal fingerprinting technique we robustly detect a significant natural contribution to the early 20th century warming. In addition, the amplitude of our simulated natural signal is consistent with the observations. Over the same period, however, we could not detect a greenhouse gas signal in the observed surface temperature in the presence of the external natural forcings. Hence our analysis suggests that external natural factors caused more warming in the early 20th century than anthropogenic factors.

    From http://journals.ametsoc.org/doi/full/10.1175/1520-0442%282003%29016%3C0426%3ASAGGFA%3E2.0.CO%3B2

    It has been observed that globally averaged warming of surface air temperature in the twentieth century occurred in two stages, early in the century from about the early 1900s to the 1940s, and late in the century from about the late 1960s to 2000 (Fig. 1b). Previous work suggests that it is likely that the early century warming was caused mostly by solar and volcanic forcing, and the late century warming mostly by the increase of greenhouse gases (partially offset by aerosol cooling). These results are confirmed here.

  33. victor, you have made a few comments since I last responded, so I shall split my response between two comments.  This first one will discuss general issues, while the second will respond explicitly on questions of science.

    @71, "sloganeering" is implicitly defined in the comments policy, which you are presumed to have read (on the basis that you are commenting):

    "No sloganeering. Comments consisting of simple assertion of a myth already debunked by one of the main articles, and which contain no relevant counter argument or evidence from the peer reviewed literature constitutes trolling rather than genuine discussion. As such they will be deleted. If you think our debunking of one of those myths is in error, you are welcome to discuss that on the relevant thread, provided you give substantial reasons for believing the debunking is in error. It is asked that you do not clutter up threads by responding to comments that consist just of slogans."

    (My emphasis)

    The point of the term "sloganeering" is that "discussion" which consists merely of restatements of your position without in fact advancing cogent arguments and/or observational evidence in favour of the position serve no greater intellectual position than to stake out your position as either a "skeptic" or a "warmist".  Intellectually, they are no more substantial than the slogans shouted at political rallies.  As such, they do nothing to advance discussion.

    @73 while the potential for bias is real, I find it extraordinary that you consider it to be a feature of climate science rather than of the "skeptics".  There are several, objective measures showing that claims of a "pause" (literally a brief cessation) or "hiatus" (literally a gap) in global warming after 1998 represent (at best) a massive disconfirmation bias by the "skeptics" (as in, they are biased towards accepting any disconfirmation of global warming, no matter how spurious).  Not least of these was the choice of the term "pause" for what was at most a reduction in the still positive trend rates.  Further objective criteria include the insistence on the use of periods starting with or very near the near record breaking 1997/1998 ENSO and terminating with or just after the 2008, and later the 2011/2012 La Ninas (both unusually strong); and the treatment of the lack of a statistically significant trend as being the lack of a trend simpliciter.

    A consequence of this bias is that "skeptics" argue against and "refute" complete misrepresentations of what is actually predicted by the theory AGW.  In some cases I have seen, they have "refuted" mischaracterizations of AGW by arguing for what AGW actually predicts.  This is certainly the case with regard to the purported 21st century "pause".  

    What AGW predicts is that, to a reasonable approximation, Global Mean Surface Temperature (GMST) is a linear function of change in forcing plus the effects of short term natural variability such as ENSO.  Climate scientists do not pretend to be solar physicists who can predict solar activity in advance.  Nor to they pretend to be geophysicists who can predict the timing and intensity of volcanic erruptions.  They do not even predent to be economists who can predict the future evolution of anthropogenic emissions.  When "predicting" the future, they use a broad range of plausible scenarios for potential future forcings (ie, projections) so that they can predict the plausible range of outcomes rather than the specific outcome.  To determine what AGW actually predicts for a specific forcing history you need to run the models (or a crude 2 box model such as Kevin Cowtan's) with the actual forcing history.  Further, as short term fluctuations of GMST are influenced by ENSO, you need to further contrain the model to match the actual ENSO fluctuations (as even those models that produce such fluctuations will not match the specific timing and intensity of ENSO events on any given run).  Alternatively you need to predict the influence of the divergence from projected values (of forcings and ENSO) and reverse engineer what the observed values would have been had those predicted values actually occured.  The later is effectively what Foster and Rahmstorf do.

    The upshot is that the features of Foster and Rahmstorf that you consider to be akin to cherry picking are just the features used to determine the mismatch between projected forcing and ENSO values (that climate scientists do not pretend to be able to predict) and the actual historical values so that a comparison can be made between that which climate scientists do purport to predict and observations can be made.  That is, they are doing what should have been done by the "skeptics" in the first place, and which is only necessary because the "skeptics" chose rhetorically advantageous misrepresentation (or at best, gross stupidity) over a proper test of the theory they want to criticize. 

    The problem with your meta-argument then becomes that in any instant where you have a critic of science unprincipled enough, or uneducated enough to completely misrepresent the predictions of the theory, and thereby assert it refuted - any attempt to correct the record by the scientists will be taken by you as proof of the scientist's bias.  You have in fact speciously argued for a massive disconfirmation bias that does not even require you to look at the evidence.

  34. Victor Grauer @82.

    Trawling the literature to find useful-sounding quotes to add weight to an argument is all very fine but in doing so you do introduce the references you cite into the discussion. And as you fail to indicate why you introduce these four refences @82 I will have to assume that you are defending your bold assertion @78 - "researchers do not see CO2 emissions as a significant contributor to the warmup during this period." I have to say that I see these references actually doing the exact opposite and pulling the rug from under your bold assertion.

    Your first reference is to an SkS page but you stick with the 'basic' version when there is also an 'advanced' version that states:-


    "Although humans were not burning very large amounts of fossil fuels or emitting large amounts of carbon dioxide (CO2) in the early 20th Century, relative to the late century, CO2 emissions were non-negligible and did play a role in the early century warming. ... As you can see, the best estimate of the anthropogenic contribution to the 1910-1940 warming is approximately 0.1 to 0.15°C."


    This seems to be quite definite in saying that AGW (of which CO2 is the largest contributor) is indeed a "significant contributor" but not a dominant one. (Victor - Nil points.)

    Your second reference, Thompson et al (2015) 'Early twentieth-century warming linked to tropical Pacific wind strength'  says a lot more than 'the early warming was almost 30% of the total when AGW was relatively weak.' (Note this 30% figure chimes well with my rough calculation presented @77  while "relatively weak" is not what you would call an exact evaluation and without context says diddly-squat.) For instance, the paper also says:-


    "Between 1910 and 1940, global temperature warmed by 0.4 C (Fig. 1) under an increase in anthropogenic forcing of only 0.3Wm

  35. Something strange happened uploading #84. I think it was probably an extranious control character hiding in a cut&paste but will wait and see if it (or our gallant moderators) can sort(s) out the mess before trying a second upload.

    Response:

    [TD] Fixed.

  36. Victor Grauer @82.
    Trawling the literature to find useful-sounding quotes to add weight to an argument is all very fine but in doing so you do introduce the references you cite into the discussion. And as you fail to indicate why you introduce these four refences @82 I will have to assume that you are defending your bold assertion @78 - "researchers do not see CO2 emissions as a significant contributor to the warmup during this period."I have to say that I see these references actually doing the exact opposite and pulling the rug from under your bold assertion.

     

    Your first reference is to an SkS page but you stick with the 'basic' version when there is also an 'advanced' version that states:-


    "Although humans were not burning very large amounts of fossil fuels or emitting large amounts of carbon dioxide (CO2) in the early 20th Century, relative to the late century, CO2 emissions were non-negligible and did play a role in the early century warming. ... As you can see, the best estimate of the anthropogenic contribution to the 1910-1940 warming is approximately 0.1 to 0.15°C."


    This seems to be quite definite in saying that AGW (of which CO2 is the largest contributor) is indeed a "significant contributor" but not a dominant one. (Victor - Nil points.)

    Your second reference, Thompson et al (2005) 'Early twentieth-century warming linked to tropical Pacific wind strength' says a lot more than 'the early warming was almost 30% of the total when AGW was relatively weak.' (Note this 30% figure chimes well with my rough calculation presented @77 while "relatively weak" is not what you would call an exact evaluation and without context says diddly-squat.) For instance, the paper also says:-


    "Between 1910 and 1940, global temperature warmed by 0.4 °C (Fig. 1) under an increase in anthropogenic forcing of only 0.3Wm^2, compared with 0.75 °C of warming under a 1.5Wm^2 increase since 1970 (refs 1,9,10; Fig. 1). Detection/attribution studies with three generations of global coupled climate models have indicated that at least some of this early century warming was probably due to natural factors, such as very few volcanic eruptions and an increase in solar output (Fig. 1). However, the magnitude of observed warming is greater than that simulated by climate models with forcing from external sources alone (0.20-0.25 °C; ref. 10), suggesting that internal variability played an important role in the early twentieth-century warming."


    Fig 1 confirms that AGW was a "significant contributor" to early 20th century warming and it would be a strange reading of the paper that concluded that these "researchers do not see CO2 emissions as a significant contributor to the warmup during this period." (Victor - Nil points.)


    Your third reference, Nozawa et al (2005), 'Detecting natural influence on surface air temperature change in the early twentieth century', presents somewhat different findings. It tells us that their initial modelling shows a large impact from GHGs throughout the 20th century, early & late, but when the net contribution of AGW is considered "the warming due to WMGHGs is offset by a cooling due to increases in anthropogenic aerosols, resulting in no significant warming until 1950s."
    Yet here the size of the GHG contribution is large enough for them to say "The trend of the global annual mean SAT in GHG is nearly equal to that in NTRL; therefore, without further investigation, we cannot conclude which factors are the main contributors to the observed early warming."
    The paper's eventual finding revolves around attribution rather than the power of the various forcings.


    "The natural forcing causes a warming trend of ~0.6K/century, which is about one half of the observed trend. This is consistent with the global annual mean SAT anomalies simulated in NTRL (Figure 1). The residual of the observed trend (~0.4K/century) may be caused by the combined anthropogenic forcings, primarily by the WMGHGs. However, the two anthropogenic signals are highly uncertain and are not detected. Therefore the cause of the residual trend is not obvious."


    This is a better account than your quote @82 from the paper's abstract. It is plain that the message from the paper is that GHG forcing (of which CO2 is the dominant contributor) are a "significant contributor". (Victor - nil points.)

    Your final reference is Meehl (2003) 'Solar and Greenhouse Gas Forcing and Climate Response in the Twentieth Century'. This is packed full of interesting stuff but again it would be a very strange reading of it which concluded that these "researchers do not see CO2 emissions as a significant contributor to the warmup during this period." You only have to note Figure 1 which shows the AGW (GHG +sulfate) contribution to the early 20th century warming to be as large as solar's (with volcanic missing). (Victor - Nil points.)

    So Victor, that is a pretty impressive score you have achieved @82. Well done you.

  37. #83 Tom Curtis: "while the potential for bias is real, I find it extraordinary that you consider it to be a feature of climate science rather than of the "skeptics"."
    OK, before we get any further, I must object to the opposition "climate science" vs. "skeptics." A great many skeptics are in fact climate scientists so that phrase is misleading in this context. As I mentioned earlier, I find it difficult to find a term characterizing those who see CO2 emissions as both a significant cause of global warming, and a clear and present danger to the future of life as we know it. I've used the term "warmist" and I've used "alarmist," but neither seems fair. "Believers" maybe? As oppposed to skeptics? Or "accepters" as opposed to "deniers"? That doesn't sound right either. If anyone has a suggestion I'd love to hear it. Meanwhile, I'll just try to avoid the issue.

    Tom: "There are several, objective measures showing that claims of a "pause" (literally a brief cessation) or "hiatus" (literally a gap) in global warming after 1998 represent (at best) a massive disconfirmation bias by the "skeptics" (as in, they are biased towards accepting any disconfirmation of global warming, no matter how spurious)."

    There's no question that many climate change skeptics are heavily biased. I cringe when I read some of the nonsense stemming from right-wing ideologues convinced that "climate change" is a communist conspiracy designed to promote world government and the sharing of wealth — or something promoted by greedy climate scientists interested only in government grants. That is bias writ large and there is no place for it in a civil discussion. It's true also that there are more subtle forms of bias that are far more difficult to discern, and I admit that I could be a victim of such bias myself. Why not? And I have no doubt that a great many fellow skeptics, if not all, are biased against the climate change mainstream (is that the phrase I'm looking for?) for one reason or another.

    However, we must recognize that, as far as science is concerned, there is an asymmetric relation between someone who offers an hypothesis and someone who critiques it. The burden of proof is on the person offering the theory, not the critic. And since there is always a strong likelihood of any scientist being biased in favor of either his own theory or a theory promoted by the group with which he's associated, special precautions should be be taken to counteract that tendency. Which is why the controlled double-blind experiment is recommended wherever possible.

    While a critic may also be biased, there is no burden of proof associated with evaluating someone else's work, nor any need to establish one's lack of bias. The person reviewing someone else's paper, for example, is not normally required to do his own research, conduct his own experiments, double-blind or not, etc. Nor is a critic required to offer an alternative theory. This might seem unfair, but this is the long established convention when a theory is considered in the scientific (or scholarly) world.

    To be perfectly clear: the theory in question is the theory that CO2 emissions due to the burning of fossil fuels have been warming the earth steadily over a long time period and as a result placing the world in grave danger. The so-called "hiatus" is an attempt to refute this theory by calling attention to a certain body of data that seems inconsistent with it. Promoters of the hiatus need not offer a counter-theory. All they need to do is demonstrate a serious inconsistency in the "climate change" theory.

    With respect to this "hiatus", there's a long long list of studies designed with the intention of disproving it, and I see no reason to uncritically accept any of them — especially when they seem designed specifically to produce a foregone conclusion. The most recent "pause buster," by Karl et al., adjusted the data in such a way as to render literally all these studies superfluous, which should have been a huge embarrassment to the mainstream climate science world, but has on the contraty been accepted with enthusiasm simply because it appears to do the job more convincingly.

    The real problem has been swept under the rug. For example, in the light of the data adjustments reported by Karl et al, it would seem that many of the numbers contributing to the results reported in the Foster/Rahmstorf paper are no longer valid, thus the formula leading to the hiatus-breaking result would have to be recalculated and would most likely come out wrong.

    The latest turn of the screw is the paper by Fyfe et al., which I'm sure you're aware of, which is critical of all such attempts, insisting that the so-called "pause" is real and needs to be taken seriously. Bias is very likely absent here, especially when we note that Michael Mann himself contributed to this research.

    Response:

    [JH] You have made several points in this post. Please note that excessive repetition is prohibited by the SkS Comments Policy, i.e,

    • Comments should avoid excessive repetition. Discussions which circle back on themselves and involve endless repetition of points already discussed do not help clarify relevant points. They are merely tiresome to participants and a barrier to readers. If moderators believe you are being excessively repetitive, they will advise you as such, and any further repetition will be treated as being off topic.

     

  38. victorag claimed "there is no burden of proof associated with evaluating someone else's work, nor any need to establish one's lack of bias." The falsehood of that claim goes beyond even the other grade school caricatures of science that victor has put forward.

  39. Victor,

    Please link your references so they can be checked.  Tom Curtis and MA Rodger have shown that your previous papers do not support your claims.  

    You are getting very repetitive.  Consider following the moderators suggestion and stop repeating the same failed assertions.  Simply repeating an assertion that has been previously shown to be incorrect will not convince anyone at this site that your arguments have merit.  Most of the regular readers have seen your posts at RealClimate and do not need to see them again, especially three or four times.

    Your characterization of Karl's paper is false, the paper adjusted the sea surface temperatures as required by science to remove measured biases.  The old ship data is obviously biased compared to the new bouy data.  You often make false assertions about scientists motives and data.  Once several of your assertions are shown to be false, your arguments become not very convincing.

  40. First, in response to the accusation that I'm repeating myself: whatever I said that might be construed as repetition was presented in a different context (a discussion of bias, in response to Tom's assertions that the notion of a hiatus is due to bias — not sure how I could respond to that without repeating some things I'd said earlier.)

    Tom Dayton: "victorag claimed "there is no burden of proof associated with evaluating someone else's work, nor any need to establish one's lack of bias." The falsehood of that claim goes beyond even the other grade school caricatures of science that victor has put forward."

    An excellent discussion of this issue appears here: http://homepages.ihug.co.nz/~edmin/Pamphlets/Pamphlet%2003%20-%20Scientific%20Method%20and%20the%20Burden%20of%20Proof.pdf

    Some excerpts:


    Filtering out delusions and wishful thinking
    It is easy to deliberately, or through mental illness,
    imagine things that do not exist. Examples that
    immediately come to mind are time-machines,
    leprechauns, hairy blue frogs, elephants that fly.
    Anyone could make up such things all day with no
    real effort. And there are an infinite number of these
    non-existent things that could potentially be
    imagined.
    But it is nearly impossible to prove that these
    things do not actually exist, or have never existed. (my emphasis-V)
    You would have to show you had looked
    everywhere the object could be and still not found
    one. Even then it could be said that the thing was
    hidden, or moved while you were looking for it, or
    you looked at the wrong time. . . 

    The same principle applies in general science. For
    this reason the onus is always on the believer to
    provide convincing evidence that the object
    believed in is not merely a laughable fantasy but
    actually exists. This is called the ‘Burden of Proof’. . . 

    As we have seen, the proof on an object's nonexistence
    is actually impossible in practice. . . 

    Default Axioms
    There is an important consequence to this - if an
    object cannot be shown to exist, the default position
    is that it does not exist. It is axiomic that something
    does not exist unless shown otherwise.

     


    With respect to bias: if I can demonstrate that a claim is unsubstantiated, then it doesn't matter whether I'm biased or not. On the other hand, if I'm attempting to establish the truth or relevance of a theory, a hidden bias might be at work in my methodology or my selection of data that makes my theory seem more convincing than it actually is. 

     

    Response:

    [JH] My cautionary note about escessive repetition was prospective.

    I also activated the link you provided. Please learn how to use the editing function to activate links. 

  41. #89 Michael Sweet: 

    "Your characterization of Karl's paper is false, the paper adjusted the sea surface temperatures as required by science to remove measured biases. The old ship data is obviously biased compared to the new bouy data. You often make false assertions about scientists motives and data. Once several of your assertions are shown to be false, your arguments become not very convincing."

    My characterization of Karl's paper had nothing to do with his claims regarding the validity of his adjustments. So you are the one making the false assertion. What I claimed is that his adjustments made the earlier studies irrelevant, another thing entirely.

  42. Congratulations, Victor. Your understanding of science has advanced from grade school to high school. Look up "naive falsificationism."

  43. It's getting very tiresome to present perfectly logical objections to climate change dogma, only to be greeted by ad hominems, nit picks (thank you, Mr. Rodger), intimidation, misreadings and condescension. Admittedly, this site is run in a far more even handed and decent manner than RealClimate, which is, for the most part, populated by rude imbeciles, encouraged to rave on with little to no supervision. 

    For the information of all concerned, I am not easily intimidated and I do not suffer fools (you know who you are) gladly. But I am also happy to engage in even handed dialogue with anyone challenging my views, provided they do so with intelligence and respect. And if my attitude is a problem for the moderators then my advice to you is very simple: ban me from the site. 

    If, on the other hand, you are interested in meaningful, no-holds-barred dialogue on one of the most important topics of the day, then freely open the gate to those like me who have ideas of their own and are not afraid to express them.

    Response:

    [JH] Your comment is a blend of agumentative and off-topic statements, moderation complaint, and sloganeering — all of which are prohibited by the SkS Comments Policy.

    If you cannot abide by the SkS Comments Policy, you will relinquish your privilege of posting on this site.

  44. Victor @ 93 and prior :

    The argumentation you present, is becoming increasingly silly.  Your mentioning of the disproving of the existence of leprechauns - is ridiculous.

    Your search for recent "Pause" in global surface temperature rise, has (so far) been unsuccessful.  If you have evidence of a claimed Pause, then it seems you have not yet presented it.  Please do not withhold such evidence - if it exists, then please present it now.

    Earlier, the analogy was made that global surface temperature was the tail on the dog body [ body = ocean ].  Victor, you have made a major Logical Fail, by ignoring the dog and instead concentrating on whether the dog has a tail [ a tail, a cropped tail, or never any tail in the first place ! ].

    Your "criticism" needs to: not only point to the absence of a tail - but also point to the absence of a dog.

    Since, for well-known physical reasons, the ocean has been warming without Pause - then it becomes not only plausible but highly probable that the "tail" would have no Pause.  And the evidence indeed shows no Pause - yes, it shows minor fluctuations as the tail wags a little : but no real Pause.

    Your desired "Pause" has become the leprechaun that  you must demonstrate.

  45. victorag @87:

    "A great many skeptics are in fact climate scientists..."

    Passing over the assumption that "skeptics" are in fact skeptical, rather dogmatically oppositional, surely you have mistated your position.  First, and this should be very clear from any excursion to WUWT, the vast majority of "skeptics" have neither qualifications in, nor understanding of climate science.  Saying that a "great many skeptics are in fact climate scientists", ie, that a large proportion of the class "AGW skeptic" are also members of the class "climate scientist" is absurd.

    I assume you merely mispoke, and intended to say that "a great many climate scientists are 'skeptics'".  Even there you are on very shaky ground.  Based on surveys of climate scientists, at most 15% and more likely << 10% of climate scientists hold a "skeptical" position on AGW.  Among publishing climate scientists, by self assessment only 2.4% of climate scientists thought there published work rejected AGW (see Table 4).  So, at best, a very small minority of climates scientists are "skeptics" - sufficiently small that their views cannot be taken as representative of climate science.

    And even among the small number of climate scientists who are "skeptics", in most cases there exist clear evidence that suggests they are biased, ie, that they hold their "scientific" opinions for reasons that are primarilly political or religious.  A significant proportion of them, for instance, are employed by right wing political think tanks, or have published for or spoken at conferences for such think tanks.  Indeed, one of the most noteworthy "skeptical" climate scientists has declared that, "I view my job a little like a legislator, supported by the taxpayer, to protect the interests of the taxpayer and to minimize the role of government", a declaration tantamount to saying that as a matter of principle he will distort the science for political ends.

    "However, we must recognize that, as far as science is concerned, there is an asymmetric relation between someone who offers an hypothesis and someone who critiques it. The burden of proof is on the person offering the theory, not the critic."

    My criticism of the "skeptic's" discussion of the "pause" was that they incorrectly stated the predictions of AGW, and that the responses that you considered to be akin to cherry picking merely established what AGW actually predicted over the relevant interval, and thereby showed that the actual temperature records followed what was expected from the theory.  Given that I am flabberghasted by your response.  Do you really intend to assert that critics of a theory may assert any phenomenon to be contrary to the predictions of the theory they criticize with no burden of intellectual rigour placed on them to establish that fact?  Seriously?  If so, your use of a "burden of proof" argument amounts to intellectual legerdemain - a piece of rhetorical prestidigitation that allows you to declare circles are squares and darkness to be light.  Even if the " ...burden of proof is on the person offering the theory", that would be completely irrelevant to the case under discussion.

    As it happens, even in more general contexts, your principle is useless.  That is because, logically, the claim that "GMST did not follow the predicted path given AGW" is also a theory.  If a burden of proof applies to those proposing theories, than a proponent of this view has a burden of proof to demonstrate to things, ie, the predicted GMST temperature trend given AGW; and that GMST did not follow that path. 

    You attempt to support your dictum with a quote @90 from comuter scientist, Stephen Minhinnick.  Event there, however, you go awry.  Stephin Minhinnick's argume (which I do not accept in any event) specifically relates to the proposition of entities, and the ontologies of climate scientists and (at least well informed) "skeptics" is the same, at least as regards the climate.  Neither proposes a distinct set of entities, be it form of radiation, or unusual subatomic particles, or whatever.  The only way that you can take Minhinnick's argument to be relevant is if we count abstractions such as trends as being entities.  But if we do that, it is the AGW "skeptics" who are proposing an additional entitity.  Specifically, AGW proponents propose an underlying linear trend over the period 1975-1997 which continues thereafter, while the "skeptics" propose the existence of a new trend from 1998 onwards.  And on that basis, they have singularly failed the burden of proof of showing a new underlyng trend. 

    "To be perfectly clear: the theory in question is the theory that CO2 emissions due to the burning of fossil fuels have been warming the earth steadily over a long time period and as a result placing the world in grave danger. The so-called "hiatus" is an attempt to refute this theory by calling attention to a certain body of data that seems inconsistent with it. Promoters of the hiatus need not offer a counter-theory. All they need to do is demonstrate a serious inconsistency in the "climate change" theory."

    (My emphasis)

    And now, apparently, we are in aggreement, except you exempt the "skeptics" from actually having to make the demonstration of inconsistency, which requires not only demonstrating the post 1998 temperature record, but also demonstrating the actual prediction of AGW (not just the projections).  And once again, demonstrating that the "skeptics" have not undertaken their task with any intellectual rigour is not akin to cherry picking.

    "The most recent "pause buster," by Karl et al., adjusted the data in such a way as to render literally all these studies superfluous, which should have been a huge embarrassment to the mainstream climate science world, but has on the contraty been accepted with enthusiasm simply because it appears to do the job more convincingly."

    First, and most obviously, Karl et al discusses just one temperature data set, and therefore cannot render analyses of other datasets superfluos.  Second, you are not entitled to assume that a reworking of (for example), Foster and Rahmstorf using the latest temperature products would not show an accelerating temperature trend.  All you can say from the update of the temperature series is that the former studies are not dated, not that they are superfluos (ie, that repeating the studies would not impact our understanding, or demonstrate any underlying trend greater than the revised temperature trends from Karl et al).  Again your argument suggest to me rhetorical legerdemain.  You appear to imply that because the "skeptic" rhetoric regarding the purported "pause" has been refuted multiple times, and in several different ways, that of itself refutes the multiple refutations.  It is only conspiracy theorests and pseudoscientists who think there theory is confirmed by the mounting of evidence against it. 

  46. With reference to my #93 post:

    I won't mind if you remove #93 completely, as it was intended primarily for the moderator(s) — as is this post. What it amounts to essentially is a plea for more agressive moderation, not less. In other words: please do your job accross the board and weed out personal attacks, condescending remarks and ad hominem arguments from whatever source. I have the impression that you are doing a far better job in this regard than the moderators at RealClimate — but you could do better. Thank you.

  47. #94 Eclectic: "The argumentation you present, is becoming increasingly silly. Your mentioning of the disproving of the existence of leprechauns - is ridiculous."

    Obviously, the "leprechauns" argument was an exreme example. However, as the article makes clear, in principle there is no difference between a claim for the existence of such beings and a claim that CO2 emissions are heating the atmosphere to an intolerable degree that endangers the future of humankind. (In fact, the second assertions looks, on its face, far more ridiculous than the former.) In both cases, the burden of proof is the same — and the challenge for the skeptic is the same. One cannot definitively prove the nonexistence of something, whether it's a leprechaun or an impending disaster. Consequently there is no burden of proof on the skeptic, only the requirement that his argument be sound.

    "Your search for recent "Pause" in global surface temperature rise, has (so far) been unsuccessful. If you have evidence of a claimed Pause, then it seems you have not yet presented it. Please do not withhold such evidence - if it exists, then please present it now."

    The evidence I presented concerned the lack of a long-term correlation between global warming and CO2 emissions. Since I've been told not to repeat myself, I won't get into that again. However, I can't help but repeat one essential reference, the paper by Fyfe et al, titled Making sense of the early-2000s warming slowdown. Here's what it says in the abstract: "It has been claimed that the early-2000s global warming slowdown or hiatus, characterized by a reduced rate of global surface warming, has been overstated, lacks sound scientific basis, or is unsupported by observations. The evidence presented here contradicts these claims."

    If you are unwilling to accept the evidence I've already offered, then at least take seriously the evidence offered in this paper, by a consortium of widely recognized climate scientists.

  48. Before dealing with #95 I'd like to say that Tom Curtis's response is a good example of the sort of thing I am always hoping to find when discussing this issue, yet so rarely do. Tom sticks to his argument and his evidence with no need for sarcasm, condescension or ad hominems. That's much appreciated, so thank you. 

    "Saying that a "great many skeptics are in fact climate scientists", ie, that a large proportion of the class "AGW skeptic" are also members of the class "climate scientist" is absurd."

    Sorry but that looks like a strawman. I never said anything about a "large proportion" — I said "a great many." Which is true. I'm sure you've seen this list before, but just in case. . .

    "And even among the small number of climate scientists who are "skeptics", in most cases there exist clear evidence that suggests they are biased, ie, that they hold their "scientific" opinions for reasons that are primarilly political or religious."

    My point regarding bias was that we are all biased to some extent. But as far as science is concerned, there is a powerful bias that must be acknowledged which can easily cause a researcher to overlook serious weaknesses in his own methods or arguments. While many skeptics have very obvious biases, if their arguments are sound, their bias can safely be ignored. So it's really better to focus on the arguments and go easy on the accusations of bias, as this really amounts to an ad hominem.


    Do you really intend to assert that critics of a theory may assert any phenomenon to be contrary to the predictions of the theory they criticize with no burden of intellectual rigour placed on them to establish that fact? Seriously? If so, your use of a "burden of proof" argument amounts to intellectual legerdemain - a piece of rhetorical prestidigitation that allows you to declare circles are squares and darkness to be light.


    No, not at all. Again you are setting up a straw man. Of course there is a burden of intellectual rigor. But that's not the same as burden of proof. In other words intellectual rigor is required, but it is not necessary for the skeptic to establish any fact. All that's needed is to demonstrate that there is a serious problem (a hidden assumption, an inconsistency, a misreading of data, etc.) with the theory being offered. 

    ". . . logically, the claim that "GMST did not follow the predicted path given AGW" is also a theory." Again: no, not at all. A critique is not a theory. The critic may have a theory of his own, but that's beside the point. Peer review would be impossible if the reviewer needed to establish his own theory before critiqueing someone's paper.


    Stephin Minhinnick's argume (which I do not accept in any event) specifically relates to the proposition of entities, and the ontologies of climate scientists and (at least well informed) "skeptics" is the same, at least as regards the climate. Neither proposes a distinct set of entities, be it form of radiation, or unusual subatomic particles, or whatever. The only way that you can take Minhinnick's argument to be relevant is if we count abstractions such as trends as being entities.


    The passages I quoted are statements regarding basic principles of science that are universally applicable. The examples provided pertain to entities, but can obviously be extended to theories of any sort. In any case, the usual AGW argument can be understood as existential and I've read many times assertions that it "really exists," that "climate change is real" and so on. How is that different, in principle, from the assertion that leprechauns are real?


    Specifically, AGW proponents propose an underlying linear trend over the period 1975-1997 which continues thereafter, while the "skeptics" propose the existence of a new trend from 1998 onwards. And on that basis, they have singularly failed the burden of proof of showing a new underlyng trend.


    Skeptics need not show a new underlying trend. All that's required is to demonstrate the lack of continuity between the strong upward trend so evident from the late seventies to ca. 1998 and what followed during the following 15 years or so. If the first period appeared to demonstrate a correlation between CO2 and warming, the second period demonstrated the falsity of that assumption. CO2 levels continued to soar while the increase in temperatures slowed considerably. If the relationship is exponential, as has been asserted, then why wouldn't that relationship continue even more convincingly into the 21st century? There is a difference between questioning an assertion and developing a whole new theory that contradicts it. A new theory isn't necessary. The burden of proof is on the person insisting that the correlation is real in the face of what looks like contradictory evidence.


    You appear to imply that because the "skeptic" rhetoric regarding the purported "pause" has been refuted multiple times, and in several different ways, that of itself refutes the multiple refutations.


    The many papers attempting to explain away the pause were prompted largely by questions raised in the field of climate science itself, not as a response to skeptics. If the later papers managed to replicate the findings of the earlier ones then that would have constituted significant evidence that the mainstream view is sound. But that's not what happened. The later papers either discovered weaknesses in the earlier ones that they attempted to correct, or else simply ignored the earlier attempts in favor of some new wrinkle. Finally, after the adjustments made by Karl et al., many of the numbers used by the earlier researchers were no longer valid, apparently, thus undermining the earlier research. Now if that research were sound it could not have so easily been undermined, no?

    Response:

    [JH] Please take the discussion of the "Pause" to a more appropriate comment thread, i.e., Aerosol emissions key to the surface warming ‘slowdown’, study says by Robert Sweeney of Carbon Brief. Sweeney's article is the most recent on this topic to be posted on SkS. 

  49. I will let Tom Curtis continue to dismantle Victor's Gish Gallops of unsupported assertions, but I will comment on one of his links:

       The Wikipedia link provided by Victor to support his claim that a "great many skeptics are in fact climate scientists" has a total of 61 living and 7 dead "climate scientists" on it. Of that 68, there is a mixture of botanists, meteorologists, geologists, ecologists, businessmen, chemists, astrophysicists, physicists, etc. Very few are really "climate scientists", except by virtue of their dissemination of tired, denier memes such as those debunked here at SkS. You can look for their names either using the SkS "Cimate MIsinformers" button (in the group below the "Most Used Climate Myths" section along the top left side of each SkS web page), or over at DesmogBlog's Denier Database.

    So, really Victor has pointed us to a page of names of fake "skeptics", of which only a very few  deserve to be called "climate scientists". To call this "a great many" is indeed strectching things. It reminds me of Project Steve. Tom CUrtis is correct in claiming that the set of "skeptical climate scientists" represents a very small proportion of the set of "climate scientists".

    ...but Victor seems to have suggested that he also posts at RealClimate. If he is indeed the same Victor, then over at RealClimate he has a long history of adding links to his posts that do not support what he says. From his short appearance here, I would say that the behaviour here matches. Whether his Morton's Demon prevents him from realizing they do not support his case, or he doesn't care and hopes that nobody will follow the links and therefore providing links will bamboozle people, I can't tell. Either way, if Victor claims that a reference says one thing, it wil almost certainly say something else.

  50. Before dealing with #95 I'd like to say that Tom Curtis's response is a good example of the sort of thing I am always hoping to find when discussing this issue, yet so rarely do. Tom sticks to his argument and his evidence with no need for sarcasm, condescension or ad hominems. That's much appreciated, so thank you. 

    "Saying that a "great many skeptics are in fact climate scientists", ie, that a large proportion of the class "AGW skeptic" are also members of the class "climate scientist" is absurd."

    Sorry but that looks like a strawman. I never said anything about a "large proportion" — I said "a great many." Which is true. I'm sure you've seen this list before, but just in case. . .

    "And even among the small number of climate scientists who are "skeptics", in most cases there exist clear evidence that suggests they are biased, ie, that they hold their "scientific" opinions for reasons that are primarilly political or religious."

    My point regarding bias was that we are all biased to some extent. But as far as science is concerned, there is a powerful bias that must be acknowledged which can easily cause a researcher to overlook serious weaknesses in his own methods or arguments. While many skeptics have very obvious biases, if their arguments are sound, their bias can safely be ignored. So it's really better to focus on the arguments and go easy on the accusations of bias, as this really amounts to an ad hominem.

    Do you really intend to assert that critics of a theory may assert any phenomenon to be contrary to the predictions of the theory they criticize with no burden of intellectual rigour placed on them to establish that fact? Seriously? If so, your use of a "burden of proof" argument amounts to intellectual legerdemain - a piece of rhetorical prestidigitation that allows you to declare circles are squares and darkness to be light.

    No, not at all. Again you are setting up a straw man. Of course there is a burden of intellectual rigor. But that's not the same as burden of proof. In other words intellectual rigor is required, but it is not necessary for the skeptic to establish any fact. All that's needed is to demonstrate that there is a serious problem (a hidden assumption, an inconsistency, a misreading of data, etc.) with the theory being offered. 

    ". . . logically, the claim that "GMST did not follow the predicted path given AGW" is also a theory." Again: no, not at all. A critique is not a theory. The critic may have a theory of his own, but that's beside the point. Peer review would be impossible if the reviewer needed to establish his own theory before critiqueing someone's paper.

    Stephin Minhinnick's argume (which I do not accept in any event) specifically relates to the proposition of entities, and the ontologies of climate scientists and (at least well informed) "skeptics" is the same, at least as regards the climate. Neither proposes a distinct set of entities, be it form of radiation, or unusual subatomic particles, or whatever. The only way that you can take Minhinnick's argument to be relevant is if we count abstractions such as trends as being entities.

    The passages I quoted are statements regarding basic principles of science that are universally applicable. The examples provided pertain to entities, but can obviously be extended to theories of any sort. In any case, the usual AGW argument can be understood as existential and I've read many times assertions that it "really exists," that "climate change is real" and so on. How is that different, in principle, from the assertion that leprechauns are real?

    Specifically, AGW proponents propose an underlying linear trend over the period 1975-1997 which continues thereafter, while the "skeptics" propose the existence of a new trend from 1998 onwards. And on that basis, they have singularly failed the burden of proof of showing a new underlyng trend.

    Skeptics need not show a new underlying trend. All that's required is to demonstrate the lack of continuity between the strong upward trend so evident from the late seventies to ca. 1998 and what followed during the following 15 years or so. If the first period appeared to demonstrate a correlation between CO2 and warming, the second period demonstrated the falsity of that assumption. CO2 levels continued to soar while the increase in temperatures slowed considerably. If the relationship is exponential, as has been asserted, then why wouldn't that relationship continue even more convincingly into the 21st century? There is a difference between questioning an assertion and developing a whole new theory that contradicts it. A new theory isn't necessary. The burden of proof is on the person insisting that the correlation is real in the face of what looks like contradictory evidence.

    You appear to imply that because the "skeptic" rhetoric regarding the purported "pause" has been refuted multiple times, and in several different ways, that of itself refutes the multiple refutations.

    The many papers attempting to explain away the pause were prompted largely by questions raised in the field of climate science itself, not as a response to skeptics. If the later papers managed to replicate the findings of the earlier ones then that would have constituted significant evidence that the mainstream view is sound. But that's not what happened. The later papers either discovered weaknesses in the earlier ones that they attempted to correct, or else simply ignored the earlier attempts in favor of some new wrinkle. Finally, after the adjustments made by Karl et al., many of the numbers used by the earlier researchers were no longer valid, apparently, thus undermining the earlier research. Now if that research were sound it could not have so easily been undermined, no?

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