Climate Feedback

Some climate change fallacies

Kevin Trenberth

The recent Asian Pacific Economic Cooperation (APEC) summit has brought further attention to climate change and what, if anything, to do about it. In spite of the IPCC findings that global warming is “unequivocal”, doubt remains in some quarters about the reality of climate change and the human cause. Issues are continually raised that have no basis, as highlighted by the recent Commentary from Syun-Ichi Akasofu in the Wall Street Journal.

Akasofu immediately starts out on the wrong foot by claiming there are two sides, those of believers and non-believers, but it is not a matter of belief, it is a matter of scientific facts! He further fails to understand the nature of the IPCC process and the extensive reviews in which all comments are addressed rigorously as the report is developed over three years. Contrary to the claim, there is no assumption by IPCC that recent warming was due to the increased greenhouse effect from increasing human produced carbon dioxide. Rather, climate models that run with and without the human-induced changes in atmospheric composition demonstrate that human warming has emerged from natural climate variability since about 1970.

Over the past 500,000 years or so, temperatures, carbon dioxide and methane have gone up and down more or less in tandem through the major ice ages and interglacial periods, as shown in ice cores. As detailed in a Real Climate blog post on this topic, in the absence of human intervention, these changes happen over time, but not at the rate at which CO2 is currently increasing in the atmosphere. Scientists know that carbon dioxide and methane changes follow rather than cause these changes in temperature between glacial periods, but they also know that these changes in greenhouse gases amplify a relatively weak forcing to help drive temperature change. To suggest otherwise, as Akasofu does, is misleading at best.

Akasofu then trots out the mistaken view that the “hockey stick” curve of temperatures over the past 1000 years showing an upward bend at the end has been discredited. In fact, it has been reinforced in the latest IPCC report, although it is given less emphasis as it is now backed up and confirmed by evidence from multiple independent studies.

He further claims that natural climate variations have been forgotten and attributes recent warming to the “rebounding effect from the little ice age”, but fails to realize that natural climate variability also has a cause. While it is true that we do not have the measurements to show what was happening in the ocean during this time, for instance, we have good reason to believe that natural internal variability played a role. To the extent that the “Little Ice Age” and “Medieval Warm Period” can be meaningfully defined, there has been much work showing that the main variations can be explained in terms of the response of the climate system to natural variability in solar and volcanic events that would have influenced surface temperature. And warm periods in the past, such as the warming in the Greenland region in the mid-twentieth century, were not global in contrast to recent warming, which is.

Climate models are not perfect, but they are useful tools for quantifying the effects of various climate processes and drivers of climate change. Akasofu decries the confused state of climatology, but it is he who is really confused, and his article only serves to confuse the general public. It is sad that a once distinguished newspaper published such misleading half-truths without verifying them.

Kevin Trenberth

Comments

  1. Report this comment

    Alexander Ac said:

    WSJ had more fallacy articles regarding the climate change in the past – RealClimate has some posts on it…

    Clearly, confusing articles are not targeted to scientists, but rather to a general public, which could be easily confused… unfortunately

  2. Report this comment

    JamesG said:

    “Scientists know that carbon dioxide and methane changes follow rather than cause these changes in temperature between glacial periods, but they also know that these changes in greenhouse gases amplify a relatively weak forcing to help drive temperature change. To suggest otherwise, as Akasofu does, is misleading at best.”

    It is far more misleading to present a weak hypothesis as a fact. No-one knows if the heating amplification is actually significant because you cannot tell from the graph. The crucial onset of cooling is never discussed by realclimate.org, Hansen, yourself or indeed anyone because it suggests the postulated CO2 amplification suddenly disappears – ie temperature falls rapidly while CO2 is still rising. This FACT tells us the original (probably solar) forcing is not “relatively weak” as the hypothesis suggests but is in fact extremely dominant. Until someone addresses this anomaly the hypothesis is not proven and very far from being fact. Hence who is misleading who?

  3. Report this comment

    Max said:

    “but they also know that these changes in greenhouse gases amplify a relatively weak forcing to help drive temperature change.”

    Well, you say it yourself, weak. I perhaps don’t understand this right, but most natural systems have negative feedback (otherwise they’d tend to be unstable pretty often!!), so small forcing changes don’t affect them very much, because they tend to buffer them out over the long run.

    Also, the effect of CO2 lessens with the amount of CO2 in the atmosphere, so that future warming might be very much smaller than current warming due to CO2. Can’t it be that we already have the “worst” warming due to CO2 behind us?

    I have some experience in the area of control engineering and system modelling, so I am a bit confused, if you say that it is a weak forcing, albeit you mention that it should have a big effect due to larger scale and (compared to glacial times) instanteous impact.

  4. Report this comment

    Bill said:

    Kevin, I disagree with a number of your statements.

    1) You claim that there are “scientific facts”, not beliefs behind the pro-AGW viewpoint commonly called the “consensus”; yet by nature of definition, a “consensus” is a common opinion shared by a group of people. Consensus does not turn an opinion into a fact. You also base that statement on the use of climate models. Climate model output is not “fact” either. It is the “opinion” of a computer programmed to produce an output. The models have not yet produced a single forecast that can be verified by real world measurements collected after the forecast is made.

    2) You claim that the hockey stick has not been debunked. The IPCC “reinforcement” of the original MBH hockey stick consists of various Mann coauthors recreating the hockey stick using reconstructions incorporating the same bristlecone proxy series that the NAS panel recommended not using as temperature proxies and using the same statistical methods that the NAS panel recommended that they not use. ClimateAudit.org has an excellent discussion of the problems with the various “reinforcements” to the hockey stick cited in the IPCC. Contrary to your claim of rigorous effort to address comments to the IPCC, Steve McIntyre’s comments about temperature proxies and reconstruction were largely dismissed, despite the fact that most of them were directly supported by the NAS panel that reviewed the original hockey stick.

    3) Finally, I believe your statement that the recent warming is “global” is incorrect. Most of the northern hemisphere warming has been confined to high latitude locations, and the southern hemisphere has no warming trend at all. See the recent “where’s waldo” series of posts at Climateaudit.org for a discussion of the temperature trends in various locations.

  5. Report this comment

    VirgilM said:

    I have a question. What are the names of the people who selected the Lead Authors and Editors of each chapter of the IPCC WG1-AR4 report? This has been a nagging question in my mind about the IPCC process.

  6. Report this comment

    VirgilM said:

    Kevin Trenberth says: “Rather, climate models that run with and without the human-induced changes in atmospheric composition demonstrate that human warming has emerged from natural climate variability since about 1970.”

    This is clearly depicted in Figure TS.22 of the IPCC WG1-AR4 report. However, in the figure, they leave off Antarctica. Granted, surface temperatures have only been measured since the 1950s on Antarctica, however, it would be interesting to see how well the climate models reproduced the flat or slightly cooling trend on Antarctica for the last 50 years as presented in TS.22. I strongly suspect that it would work against the message (and against Kevin’s argument) that Figure TS.22 was trying to

    present (i.e. Climate models can replicate past climate).

  7. Report this comment

    Andre Bijkerk said:

    Trenberth said:

    “Over the past 500,000 years or so, temperatures, carbon dioxide and methane have gone up and down more or less in tandem through the major ice ages and interglacial periods, as shown in ice cores.”

    Yes but that doesn’t mean that one caused the other. I’d like to show here, what is wrong with that:

    http://earth.myfastforum.org/about134.html

  8. Report this comment

    M. D. Smith said:

    Bill’s assertion that ‘the southern hemisphere has no warming trend at all’ is simply false. Both the HadCRUT3 and NCDC datasets show clear warming trends in both hemispheres, beginning in the mid- to late-1970s. The slightly steeper temperature increase in the northern hemisphere is an entirely predictable consequence of the higher proportion of land to sea surface area north of the equator.

  9. Report this comment

    Paul said:

    “He further fails to understand the nature of the IPCC process and the extensive reviews in which all comments are addressed rigorously as the report is developed over three years.”

    As a layman, I would be curious of what others think of Roger Pielke Sr.’s criticism of the IPCC assessment process. See e.g. "If instead of evaluating research in climate, suppose a group of scientists introduced a new cancer drug that they claimed could save many lives. There were side effects, of course, but they claimed that the benefit far out weighed these risks. The government than asked these scientist to form an assessment Committee to evaluate this claim. Colleagues of the group of scientists who introduced the drug are then asked to serve on this Committee, along with the developers.

    If this occurred, of course, there would be an uproar of protest! This is a clear conflict of interest.

    Yet this is what has happened with the IPCC process! The same individuals who are doing primary research in the role of humans on the climate system are then permitted to lead the assessment! There should be an outcry on this obvious conflict of interest, but to date either few recognize this conflict, or see that since the recommendations of the IPCC fit their policy and political agenda, they chose to ignore this conflict. In either case, scientific rigor has been sacrificed and poor policy and political decisions will inevitably follow."

    http://climatesci.colorado.edu/2007/09/01/the-2007-ipcc-assessment-process-its-obvious-conflict-of-interest/

  10. Report this comment

    Pat Neuman said:

    An incorrect statement was posted earlier (by Bill), that “Most of the northern hemisphere warming has been confined to high latitude locations,” …

    Temperatures at U.S. climate stations in the Midwest, Great Plains and Rocky Mountain regions show strong upward trends in recent decades (view plots with more than 100 years of data at the linked website via this comment).

    The Midwest, Great Plains and Rocky Mountains are not located in “high latitude locations”.

  11. Report this comment

    Oliver K. Manuel said:

    CLIMATE CHANGE FALLACY

    The entire climate change debate is based on this fallacy:

    “The reasons for changes in Earth’s temperature can be deciphered by studying the historical record of changes in Earth’s temperature.”

    Space-age measurements have shown that Earth’s heat source is a variable star, a supernova remnant that ejected the material now orbiting it as meteors, planets, moons, and asteroids:

    http://www.omatumr.com/Origin.htm

    This 1976 conclusion was confirmed in 2006 when analysis of a comet showed that the comet also came from the Sun.

    /news/blog/2006/12/comet_born_of_our_own_sun.html

    We already knew that Earth’s heat source is unsteady and that some solar variables (magnetic and sunspot activity and the abundances of elements and isotopes at the solar surface) correlate with Earth’s climate.

    For example, the “Maunder minimum” in sunspot and solar surface magnetic activity coincides with the coldest part of the Little Ice Age, 1645 to 1714.

    High abundances of metals like iron and nickel were found at the surfaces other stars identified as “Maunder minimum” stars in a 2004 study.

    http://www.berkeley.edu/news/media/releases/2004/06/01_maunder.shtml

    The reasons for changes in Earth’s temperature can be deciphered if scientists will abandon the illusion that our heat source is a ball of hydrogen with a steady H-fusion reactor at its core and start reporting changes in the solar variables (magnetic and sunspot activity and surfaces abundances of elements and isotopes) that correlate with changes in Earth’s temperature.

    With kind regards,

    Oliver K. Manuel

    http://www.omatumr.com

    http://www.ballofiron.com

  12. Report this comment

    David B. Benson said:

    JamesG, Max, Oliver K. Manuel (maybe others) I urge you to go to the ‘Science’ section of the RealCLimate site and click on the first link, to the AIP Discovery of Global Warming site. Read it. At a minimum you won’t be confused about the state and nature of climatology.

  13. Report this comment

    Dennis Wingo said:

    I challenge any climate scientist out there to show, by using the basic physics involved, why CO2 is a forcing factor on climate at the partial pressure increase of the last century.

    Linking to a bad explanation on realclimate.org does not count.

  14. Report this comment

    Majorajam said:

    JamesG,

    Even with my barely cursory understanding of the climate, the flaws in your logic jump off the page. For example, if changes in temperature relate linearly to changes in green house gas concentrations in the upper atmosphere, that yields a diminishing marginal impact on temperature of increased concentrations due to the logarithmic forcing of GHGs. In fact, given the nature of the forcing, you will not get an inflection point and a reversal in the temperature, i.e. a cooling, if and only if concentrations of the gas increase exponentially with temperature. I can’t see how that dog would hunt, and certainly not indefinitely. Ultimately, there are many dozens of factors that could account for the ultimate cooling of the climate that would have zero to do with the original (probably orbital) forcing, and any hypothesis would have to account for each of these potential forcings in the context of the relevant cycles and dynamics over an appropriate time scale. If your belief is that what you’ve written reductio ad absurdum refutes the role of GHGs in the climate system, you have some blanks to fill. And then some.

  15. Report this comment

    RT said:

    Dennis Wingo,

    I challenge YOU to show, by using the basic physics involved, that current warming patterns can explained without including human CO2 emissions.

    Linking to a bad explanation on any climate change denial site does not count.

    Climate change sceptics find critisising very easy but actually producing a workable model that supports their position impossible.

  16. Report this comment

    JamesG said:

    Majorajam

    By studying the graphs you must surely agree that the most obvious hypothesis (say A) is that heating and cooling are controlled by the same forcing and that GHG effects are hence not too significant as a feedback. That really needs no further elaboration. OTOH the weak forcing – strong feedback hypothesis (say B) is rather less obvious so that is the one that needs to be fully explained to overturn the more acceptable explanation. At least that’s usually how science works. However I didn’t mean to discredit the role of GHG’s in the climate system. Indeed the fact that the downslopes are far shallower than the upslopes perhaps demonstrates this amplification effect. However it doesn’t appear to be the dominant factor in the past. BTW you said forcing when you should have said feedback – only anthropogenic GHG’s are a forcing. You also say there may be dozens of cooling factors but didn’t name any – it’s ok; nobody does. And you seem to misunderstand that orbital changes actually change the solar forcing. Finally your argument about the logarithmic effect of GHG’s actually argues even more against hypothesis B since everyone can plainly see that the GHG’s and temperatures rise and fall in tandem which is entirely consistent with hypothesis A but not with hypothesis B.

  17. Report this comment

    Timo Hämeranta said:

    The actual reason for Trenberth to criticise Akasofu’s argument “rebounding effect from the little ice age” is that he relies on models, but modellers are unable to include in their models long internal natural variations, oscillations and cycles, e.g. well-known and -documented 200 or 1500 yr cycles.

    Please see: Rahmstorf, Stefan, 2003. Timing of abrupt climate change: A precise clock, Geophys. Res. Lett., 30(10), 1510, doi:10.1029/2003GL017115, May 21, 2003: Many paleoclimatic data reveal a ~1,500 year cyclicity of unknown origin….

    Climatology is not at all settled the way many scientists try to argue.

  18. Report this comment

    Kevin Trenberth said:

    To the comment on the “fallacies post” by Virgil, all IPCC authors are selected by governments based on nominations to them. From the nominations, the final authors are selected to balance the expertise and geographic representation. Over 70% of the IPCC authors in the latest WG I report were new to the process.

  19. Report this comment

    Kevin Trenberth said:

    Max, the response to carbon dioxide is not linear to carbon dioxide concentration but now logarithmic. Still, we can use radiative transfer models to compute the effect very accurately. Even if the carbon dioxide band is saturated in the center, the tails of the band continue to contribute. The climate models do these calculations so this is not guesswork.

  20. Report this comment

    Kevin Trenberth said:

    VirgilM – In Antarctica there has not been much warming except in the Antarctic Peninsula. Changes have occurred in the atmospheric circulation, that are well documented in chapter 3 of the report. These contribute to a stronger polar vortex that is accompanied by more isolated cold air over Antarctica. This is now well understood and it comes mainly from the ozone hole, that is unique to Antarctica. However, increasing greenhouse

    gases contribute also. This change is replicated in models.

  21. Report this comment

    Majorajam said:

    JamesG,

    I mention orbital because it is understood that the effect of orbital variation on the earth’s collective exposure to solar radiance indicates the earth should be cooling at the moment, not warming dramatically as is the case. By contrast, there is no demonstrable, and more importantly, falsifiable cosmic ray/solar trend at the moment, so the preference is for specifics. One might think the circumstance of the orbital forcing would have implications for hypothesis A’s validity, but perhaps this is down to my naivete.

    More generally, it is quite a slight of hand to insist that hypothesis A is somehow the most obvious. Aside from the rhetorical utility to those whose belief systems are uncomfortable with Anthropogenic Global Warming, why would that be? Is a system with decreasing marginal positive feedback- like a snowball accelerating down a hill until it finds a plateau- so complex that we must ignore evidence of it in favor of less persuasive but monocausal explanations, e.g. variations in gravity? And much like momentum can carry that snowball for a time across flat snow, eventually it will come to a stop unless sufficient force is applied to keep it going. In the context of the climate system, if you are saying that atmospheric concentrations of GHGs build at an exponential rate against linear changes in temperature, indeed, we must accept hypothesis A. If not, again, probably better to start filling in the blanks.

  22. Report this comment

    PaulM said:

    Kevin Trenberth does indeed highlight some climate change fallacies.

    He says the hockey stick has been ‘reinforced’ in the latest IPCC report.

    In fact, the infamous flat graph of Mann et al has been shown to be

    flawed by a team of expert statisticians and has been dropped by the

    IPCC. In the third report (2001) it featured prominently on page 3

    of the summary, but in the new summary it doesn’t feature at all

    and they only say it is ‘likely’ that temperatures now are the highest

    in 1300 years. Graphs of temperature reconstructions do not appear

    until page 467, where it is notable that the graphs disagree widely

    with eachother and do not look like a hockey stick. More recent

    reconstructions such as Moberg et al (Nature, 2005) show a temperature

    difference of around 0.8 degrees between the medieval period and the

    little ice age, inconsistent with the hockey stick picture and

    consistent with the historical picture.

    He goes on to imply that the medieval warm period was not global,

    when in fact there are papers showing the MWP all over the world

    including Antarctica. He says the current warming is global,

    which is not true. The IPCC says there is a ‘lack of warming’ in

    Antarctica and no trend in sea ice there. In Iceland, the warmest

    decade of the 20th century was the 1930s. In the US, the recent

    media publicity surrounding NASA’s error has drawn attention to the

    fact that the warmest year was 1934. At least, that was the case until

    two weeks ago, when NASA ‘adjusted’ the numbers again, reducing

    temperatures in the 1880s by up to 0.14 degrees, so that 1934 now ties

    with 1998.

    Finally he neglects to mention that Akasofu is director of the

    International Arctic Research Center with a distinguished track record

    of scientific research. He is not ‘confused’, and is not someone whose

    view can be easily dismissed.

  23. Report this comment

    JamesG said:

    Majorajam

    We are discussing the mechanisms of past warming here. Anthropogenic Global Warming (AGW) doesn’t even enter into it. Hypothesis A is more obvious simply because we usually assume that effect follows cause – hardly “sleight of hand”. If someone is arguing that cause follows effect then it is they who have to fill in the blanks. Indeed there are no blanks with hypothesis A: It even allows for some non-dominant feedback amplification as I explained above. Akasofu therefore only states what should be more obvious to an unbiased observer. I highly doubt that even Kevin Trenberth disagrees with that basic point. And I repeat: hypothesis A doesn’t require any argument of logarithmic versus linear effects because it argues that any feedback amplification is not significant. Finally, that the ice-core records don’t show CO2/CH4 feedback being dominant doesn’t diminish the AGW theory at all, since that mainly relies on water vapour positive feedback from immediately produced man-made GHG’s. I just see this particular argument as an unscientific spin on the truth which makes one seriously doubt the judgment of anyone who unthinkingly parrots it.

  24. Report this comment

    Majorajam said:

    JamesG

    My understanding was that central physical dynamic of concern both in the paleoclimatic record and wrt to the theory of AGW is the radiative properties of GHGs in the upper atmosphere. That water vapor was a net positive feedback but not a large one due to cloud albedo.

    You say: “Hypothesis A is more obvious simply because we usually assume that effect follows cause”

    Does this mean that the dynamics of a rock disturbed by a hiker on a mountain are best described by the force that originally caused its motion? That it moved, accelerated, slowed and then came to rest again all as a result of the movement of the hiker’s foot? Is this in line with your opinion on what constitutes an obvious explanation, the hypothesis A which it is not a slight of hand to suggest we must have a high burden of proof to reject? I just see this particular argument as obstructionist to say nothing of the fact that implying a primia facie dissonance between the ice core record and consensus of climate science as given by any reputable survey is tantamount to alledging either some sort of conspiracy or that climate researchers are uniquely dull. Again, this could be your argument, but that’s not clear- these are the types of blanks you should be looking to fill.

  25. Report this comment

    Dave said:

    I ain’t no high falutin’ scientist, but if temperatures are as high as they’ve been in 1300 years, then what in tarnation made it so hot 1300 years ago?!?!?!

    T’weren’t no man-made CO2 from evil corporations.

    Just mighta been the sun, ya know?

    That’s my opinion, and it ought to be yers.

    Redstate Redneck

  26. Report this comment

    JamesG said:

    Majorajam

    Looks like this issue has finally been studied in some more detail:

    http://www.usc.edu/uscnews/stories/14288.html

    Filling in those blanks perhaps? Some fallacy! An apology to Akasofu should be forthcoming.

    FYI Check this, but I gather that most of the warming in current GCM’s comes from H2O feedback. Clouds are not considered yet owing to conflicting information.

  27. Report this comment

    Oliver K. Manuel said:

    Redstate Redneck is right.

    The debate over global warming is based on a fallacy — a confusion of cause and effect.

    The heat source for planet Earth does not reside here.

    Therefore the cause of global warming cannot be deciphered by studies that are limited to planet Earth.

    That is like a diet plan that ignores food intake!

    Earth’s heat source is a variable star, a remnant of the supernova that ejected the material now orbiting the Sun as planets, moons, asteroids and meteors:

    http://www.omatumr.com/Origin.htm

    Sunspots peaked during the last solar cycle (#23) in 2000-2002. Subsequent measurements of the [O]/[Fe] ratio at the solar surface found a “progressively lower oxygen abundance”.

    It was suggested that, “At the present rate, the Sun will be oxygen free in around 2015” [See “The Solar Oxygen Crisis” presented on 7 June 2006 at the HAO (High Altitude Observatory) Colloquia

    http://tinyurl.com/2umqvt

    The Astrophysical Journal published similar findings on 10 May 2007 in a paper entitled “The solar oxygen crisis: Probably not the last word” [Ap. J. 660 (2007) L153-L156].

    http://tinyurl.com/35dtdd

    How could Earth’s climate be insulated from such variations in the Sun?

    With kind regards,

    Oliver K. Manuel

    http://www.omatumr.com

    http://www.ballofiron.com

  28. Report this comment

    Bishop Hill said:

    M D Smith said:

    Both the HadCRUT3 and NCDC datasets show clear warming trends in both hemispheres, beginning in the mid- to late-1970s.

    The Hadley centre will not release their data and code to allow replication of their work. Until they do it should be treated as junk science.

  29. Report this comment

    Willis Eschenbach said:

    John Pearson, you say:

    It took me about 30 seconds to obtain the HADCRUT3 data set. I know you (blog editors) are busy and all, but couldn’t we at least edit out the claims that can be debunked in less than say 1 minute with google?

    There is a misunderstanding here. Bishop Hill is talking about the raw data used to create the HadCRUT3 dataset, not the final gridded data you have cited. The Hadley Centre has refused to release this raw data, despite (among other requests) my application under the Freedom of Information Act for the release of the raw data. It is this kind of scientific malfeasance that throws the whole field into disrepute.

    Finally, several foolish mistakes that I have made in the past have cured me of the error of assuming that someone has made an incredibly obvious mistake, one that can be resolved by one minute’s googling. Most of the folks posting here are knowledgeable enough to avoid that kind of egregious error, so it is good to be cautious before accusing them of stupidity.

    All the best,

    w.

  30. Report this comment

    Willis Eschenbach said:

    Dr. Trenberth, you say:

    He further fails to understand the nature of the IPCC process and the extensive reviews in which all comments are addressed rigorously as the report is developed over three years.

    Here’s an example of how the comments are “addressed rigorously”. The comment to the IPCC FAR concerns a fundamental question, that of how to determine the statistical significance of trends in datasets containing long term persistence, such as climate datasets. This was the comment:

    Throughout the chapter, results of linear trend analyses are presented that include estimates of statistical significance. In two specific sections of the chapter (page 3-9, lines 18-22 and page 3-116, lines 53-56), the comment is made that the statistical significances of trends in variables estimated using Restricted Maximum Likelihood regression (REML) — which is the method used within the report — are likely to be overestimated; with citations given for Zheng and Basher, 1999 and Cohn and Lins, 2005.

    On page 3-116, lines 55-56, after acknowledging that this problem stems from the presence of long-term persistence in the underlying climatic processes, the report then states “Nevertheless, the results depend on the statistical model used, and more complex models are not as transparent and often lack physical realism.” Indeed, the results do depend on the model used and, as pointed out by Cohn and Lins, 2005, simple models (like REML) do not capture the complexity of long-term persistence — that’s why results based on the use of simple models are in error. The comment that “more complex models are not as transparent and often lack physical realism” contradicts the central point of Cohn and Lins, 2005.

    If long-term persistence exists within climatic processes, and the 4AR draft says that it does (page 3-116, lines 53-54), then a more complex model, such as that used by Cohn and Lins (2005) MUST be used to estimate statistical significance. This is not a matter of subjective model choice but, rather, of selecting a model that can be demonstrated as capturing the inherent behavior of the process in question. REML, and all other simple linear models, do not capture the observed temporal behavior of land surface temperature, sea surface temperature, precipitation, and any other hydro-climatic variable.

    The 4AR draft is reporting statistical significances that are known to be gross overestimates. To address this problem, the authors have two choices. One is to recalculate the statistical significance estimates of all variables for which significance is currently reported using a procedure such as Cohn and Lins’ (2006) Adjusted Likelihood Ratio Test that is specifically designed for use with data exhibiting long-term persistence.

    Alternatively, the report could retain all of the current information regarding trend magnitude (which Cohn and Lins document as being insensitive to the method used to estimate it), but remove all reference to statistical significance — in text, tables and figures. Indeed, the latter option may be desirable because, as noted by Cohn and Lins, “it may be preferable to acknowledge that the concept of statistical significance is meaningless when discussing poorly understood systems.”
[Govt. of United States of America (Reviewer’s comment ID #: 2023-132)]

    There are a couple of things to note here. One is that the Cohn and Lins paper is cited by the IPCC in the chapter. Another is that the problem is clearly described, with appropriate citations, and a couple of solutions to the problem are proposed – either compute the error estimates correctly, or omit them entirely.

    Now, here’s how this very clear and relevant comment was “rigorously addressed” by the IPCC:

    Rejected, but change made. After already looking into this issue it is apparent that the Cohn and Lins method is likely wrong and misrepresents statistical significance by overestimating long term persistence. There is no known paper showing these are improved models. We have computed the Durbin Watson statistics for all series and none suggest that residual long term persistence is present. It does NOT mean the simple models are in error. Lines 54-56 redone.

    A couple of things to note about this “rigorous addressing” of the comment. First, there is no paper or study cited. The reviewer merely says “it is apparent” that Cohn and Lins, a peer reviewed paper cited by the IPCC itself, is wrong. “It is apparent”?!? What kind of science is that?

    Second, there is a peer-reviewed paper that shows that “these are improved models” and the REML model is inadequate … the peer-reviewed Cohn and Lins paper under discussion. The author offers no studies (peer reviewed or not) showing that the Cohn and Lins paper is incorrect, so the reviewer’s statement about improved models is totally unsupported.

    Third, the Durbin-Watson statistic is not an appropriate test for long-term persistence. It is purely a test for lag-1 (short term) persistence. The reviewer does not even understand basic statistics.

    From this example alone, it is clear that “the extensive reviews in which all comments are addressed rigorously” are not rigorous or scientific at all. They are merely a quashing of opposing views, without even a thin veneer of science to justify them.

  31. Report this comment

    John E Pearson said:

    Willis Eschenbach wote:

    “The Hadley Centre has refused to release this raw data, despite (among other requests) my application under the Freedom of Information Act for the release of the raw data.”

    The Hadley Center should release their raw data but it is ridiculous to argue that all experimental results that are published without public access to the raw data should be considered “junk science”. Given modern computer hard drive sizes, raw data should be published along with all experimental results, but that is not the norm. If one dismisses as “junk science” all experimental results for which raw data are not available, one is dismissing the vast majority of all experimental results in all fields. Perhaps Nature should take up the cause and require publication of all raw experimental data?

  32. Report this comment

    Bishop Hill said:

    John E Pearson

    You say that "it is ridiculous to argue that all experimental results that are published without public access to the raw data should be considered “junk science”."

    Nobody has said such a thing. I said that the CRU results should be treated as junk science because they have refused to release their data and code.

  33. Report this comment

    Willis Eschenbach said:

    John Pearson, thank you for your comment. You say:

    Perhaps Nature should take up the cause and require publication of all raw experimental data?

    Indeed they should. The National Science Foundation already has this requirement (although unfortunately they often refuse to enforce it).

    The problem, of course, is replication. In climate science, there are many results which cannot be replicated, verified, or checked because the authors have actively refused to archive their data. In those cases, yes, their results should be treated as junk science. Replication is the essence of science, and refusing to allow your work to be replicated puts you out of the scientific bounds.

    Why do these scientists refuse to archive their data? Occam’s Razor suggests that people hide something because … well … because they have something to hide. Unfortunately, this refusal is all too common in climate science.

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    Willis Eschenbach said:

    John V, another comment on what you said regarding the publication of data:

    Perhaps Nature should take up the cause and require publication of all raw experimental data?

    Actually, it turns out Nature does have a policy on the availability of data, which says, inter alia:

    An inherent principle of publication is that others should be able to replicate and build upon the authors’ published claims. Therefore, a condition of publication in a Nature journal is that authors are required to make materials, data and associated protocols available in a publicly accessible database (as detailed in the sections below on this page) or, where one does not exist, to readers promptly on request,

    w.

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    Oliver K. Manuel said:

    THE MAIN FALLACY

    Certainly raw data should be archived, whether they are collected at the Sun – Earth’s heat source – or at various locations on Earth.

    The main fallacy in the climate change debate arises from the assumption that changes in Earth’s climate — on a time scale of decades, centuries, tens or even hundreds of centuries — cannot be caused by changes in the Sun.

    If the Sun were a massive ball of hydrogen, heated by a H-fusion reactor at its core, then changes at the solar core would be delayed by about 30 My (million years), the diffusion time for radiation from the core of the Sun to its surface [See William A. Fowler, “What cooks with solar neutrinos?” Nature 238 (1972) pp. 24-36].

    http://www.nature.com/nature/journal/v238/n5358/abs/238024a0.html

    However observations reveal that the Sun is a violently dynamic object on a much shorter time scale. It has continuous Sun-quakes (the solar equivalent of Earthquakes), exhibits an easily recognized 11-year cycle of magnetic activity and sunspots, and oscillates on a much shorter time scale like a pulsar [See: Peter Toth, “Is the Sun a pulsar?” Nature 270 (1977) pp. 159-160].

    http://www.nature.com/nature/journal/v270/n5633/abs/270159a0.html

    Dr. Theodore Landscheidt identified a mechanism that may explain changes in the solar variables that are linked with changes in Earth’s climate: Interactions of the Sun with the orbital motions of the four largest planets accelerate and decelerate the Sun in a wobbling and jerky orbit about the center of mass of the solar system.

    http://www.john-daly.com/po.htm

    Such cyclic irregularities in the motion of the Sun likely cause the position of its compact neutron core to shift relative to the solar surface and produce MEASURABLE changes in solar variables (magnetic and sunspot activity and surface abundances of isotopes and elements, e.g., [O]/[Fe]) that are linked with changes in Earth’s climate.

    http://www.physorg.com/news97326842.html

    With kind regards,


    Oliver K. Manuel


    http://www.omatumr.com


    http://www.ballofiron.com

  36. Report this comment

    Dr. Dean said:

    Kevin …

    I hate to break it to you, but you and the rest of the AGW supporters are about to be proven wrong!

    If those of us who are willing to read and consider ALL the evidence, not just the theories of CO2, can hold out for about 5 more years, we will see the Climate Science people trying to ascribe Global Cooling to CO2 once more. At that point, Climate Scientist who have put too much emphasis on CO2 will be completely discredited.

    The public bought the scare of the 70s, that our emissions were driving us to a new ice age. Even more of the public is now buying the line that Climate is governed by our CO2 emissions. However, when the Climate Scientists once more try to tie Global Cooling to CO2 emissions, the Public will turn on you.

    But what will nail the coffin shut will be that the predictions of alternative theories will be proven right. That will hurt.

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    Matthew Loxton said:

    If those of us who are willing to read and consider ALL the evidence, not just the theories of CO2, can hold out for about 5 more years, we will see the Climate Science people trying to ascribe Global Cooling to CO2 once more

    I am rather curious as to what it would mean to say that “ALL” the evidence for some proposition was considered. How would one know what this was unless the absolute truth were already known, after all, how does one know relevance unless the finality is known.

    The standard mechanism of the Popperian hypothetico-deductive model is to pose an argument, grounded or instrumental, and subject it to tests which threaten it with embarrassment.

    Dr.Dean, are you proposing we amend the practice to waiting until every shred of evidence is in before posing an hypothesis, or would in be ok with you if science carried on as usual?

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