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Global Warming Since 1997 Underestimated by Half

Filed under: — stefan @ 13 November 2013

A new study by British and Canadian researchers shows that the global temperature rise of the past 15 years has been greatly underestimated. The reason is the data gaps in the weather station network, especially in the Arctic. If you fill these data gaps using satellite measurements, the warming trend is more than doubled in the widely used HadCRUT4 data, and the much-discussed “warming pause” has virtually disappeared.

Obtaining the globally averaged temperature from weather station data has a well-known problem: there are some gaps in the data, especially in the polar regions and in parts of Africa. As long as the regions not covered warm up like the rest of the world, that does not change the global temperature curve.

But errors in global temperature trends arise if these areas evolve differently from the global mean. That’s been the case over the last 15 years in the Arctic, which has warmed exceptionally fast, as shown by satellite and reanalysis data and by the massive sea ice loss there. This problem was analysed for the first time by Rasmus in 2008 at RealClimate, and it was later confirmed by other authors in the scientific literature.

The “Arctic hole” is the main reason for the difference between the NASA GISS data and the other two data sets of near-surface temperature, HadCRUT and NOAA. I have always preferred the GISS data because NASA fills the data gaps by interpolation from the edges, which is certainly better than not filling them at all.

A new gap filler

Now Kevin Cowtan (University of York) and Robert Way (University of Ottawa) have developed a new method to fill the data gaps using satellite data.

It sounds obvious and simple, but it’s not. Firstly, the satellites cannot measure the near-surface temperatures but only those overhead at a certain altitude range in the troposphere. And secondly, there are a few question marks about the long-term stability of these measurements (temporal drift).

Cowtan and Way circumvent both problems by using an established geostatistical interpolation method called kriging – but they do not apply it to the temperature data itself (which would be similar to what GISS does), but to the difference between satellite and ground data. So they produce a hybrid temperature field. This consists of the surface data where they exist. But in the data gaps, it consists of satellite data that have been converted to near-surface temperatures, where the difference between the two is determined by a kriging interpolation from the edges. As this is redone for each new month, a possible drift of the satellite data is no longer an issue.

Prerequisite for success is, of course, that this difference is sufficiently smooth, i.e. has no strong small-scale structure. This can be tested on artificially generated data gaps, in places where one knows the actual surface temperature values but holds them back ​​in the calculation. Cowtan and Way perform extensive validation tests, which demonstrate that their hybrid method provides significantly better results than a normal interpolation on the surface data as done by GISS.

The surprising result

Cowtan and Way apply their method to the HadCRUT4 data, which are state-of-the-art except for their treatment of data gaps. For 1997-2012 these data show a relatively small warming trend of only 0.05 °C per decade – which has often been misleadingly called a “warming pause”. The new IPCC report writes:

Due to natural variability, trends based on short records are very sensitive to the beginning and end dates and do not in general reflect long-term climate trends. As one example, the rate of warming over the past 15 years (1998–2012; 0.05 [–0.05 to +0.15] °C per decade), which begins with a strong El Niño, is smaller than the rate calculated since 1951 (1951–2012; 0.12 [0.08 to 0.14] °C per decade).

But after filling the data gaps this trend is 0.12 °C per decade and thus exactly equal to the long-term trend mentioned by the IPCC.


The corrected data (bold lines) are shown in the graph compared to the uncorrected ones (thin lines). The temperatures of the last three years have become a little warmer, the year 1998 a little cooler.

The trend of 0.12 °C is at first surprising, because one would have perhaps expected that the trend after gap filling has a value close to the GISS data, i.e. 0.08 °C per decade. Cowtan and Way also investigated that difference. It is due to the fact that NASA has not yet implemented an improvement of sea surface temperature data which was introduced last year in the HadCRUT data (that was the transition from the HadSST2 the HadSST3 data – the details can be found e.g. here and here). The authors explain this in more detail in their extensive background material. Applying the correction of ocean temperatures to the NASA data, their trend becomes 0.10 °C per decade, very close to the new optimal reconstruction.


The authors write in their introduction:

While short term trends are generally treated with a suitable level of caution by specialists in the field, they feature significantly in the public discourse on climate change.

This is all too true. A media analysis has shown that at least in the U.S., about half of all reports about the new IPCC report mention the issue of a “warming pause”, even though it plays a very minor role in the conclusions of the IPCC. Often the tenor was that the alleged “pause” raises some doubts about global warming and the warnings of the IPCC. We knew about the study of Cowtan & Way for a long time, and in the face of such media reporting it is sometimes not easy for researchers to keep such information to themselves. But I respect the attitude of the authors to only go public with their results once they’ve been published in the scientific literature. This is a good principle that I have followed with my own work as well.

The public debate about the alleged “warming pause” was misguided from the outset, because far too much was read into a cherry-picked short-term trend. Now this debate has become completely baseless, because the trend of the last 15 or 16 years is nothing unusual – even despite the record El Niño year at the beginning of the period. It is still a quarter less than the warming trend since 1980, which is 0.16 °C per decade. But that’s not surprising when one starts with an extreme El Niño and ends with persistent La Niña conditions, and is also running through a particularly deep and prolonged solar minimum in the second half. As we often said, all this is within the usual variability around the long-term global warming trend and no cause for excited over-interpretation.

263 Responses to “Global Warming Since 1997 Underestimated by Half”

  1. 51


    Actually, the weather station in the city of North Pole, Alaska, is correctly located:

  2. 52
    Dan says:

    Why do I suspect this significant paper will not get nearly the media coverage (if any) that all the “warming has paused!” noise did? Sigh.

  3. 53
    Aubrey Meyer says:

    The problem of under-estimation of the rates of climate change translates into a political process that under-estimates the rate of climate-policy required to avoid runaway.

    IPCC AR5 WG1 results show ‘carbon budgeting’ is now needed to avoid 2 degrees [and this a plus] while depending on climate models that under-estimate the rates of change we’re faced with and therefore the rates of response required [and this is a minus]: –

    Global policy models are needed.

    Here’s a heuristic device that is a step in that direction: –

    Not finished yet.

  4. 54
    MARodger says:

    Over the last few years, the “other side” have been making such a lot from the “pause”, stretching it back into the mid-1990s to make it sound like something big. In my opinion, they were quite lucky the HadCRuT3/4 update didn’t shoot their fox. If Cowtan & Way have managed a clean shot, good for them. Their level of success with this will probably be proportional to the level of noise it eventually generates.

    So far, the only noise is “over here”. With the exception of Judy Curry, the “other side” appears silent on Cowtan & Way. Curry (blog-posting about another paper in the same screed, so nothing too important then) dismisses the Cowtan & Way findings because ☺ Kriging infills shouldn’t cross land/ocean/icepack boundaries, ☺ satellite data will pick up temperature inversions and ☺ Arctic temperature data suffers “temporal inhomogeneities” which will play havoc with your trends, apparently. So she concludes – ignore Cowtan & Way: we can still rely on the old favorite, that graph of Ed Hawkins so loved by Curry & her chum David Rose of the Daily Rail.

  5. 55
    Neven says:

    This post is a real concern troll magnet.

    Of course, it’s clear that if you accept this work from two non-climate scientists, you must also accept the Oregon Petition.

  6. 56
    SCM says:

    Jerry says:

    If the claims this paper makes are true, I think they should be disseminated with some care because to the unqualified observer, they will tend to undermine the credibility of the whole body of research. “If they are right,” people will say, “Everything we have been told so far must have been quite wrong.” Greatly wrong, as the study itself says.

    What a strange comment. The previous work on temperatures has been up front about what is missing and what has had to be interpolated. This paper is one attempt to improve on that. Time will tell how it stands up but it hardly turns climate science on its head. It does however provide a result which makes sense of other arctic observations (melting sea ice etc).

  7. 57

    Below my post on this study, Peter Thorne gave a link to the free manuscript of the pay-walled article.

    I hope I can still comment here, at Climate Etc. my comments do not appear any more.

  8. 58
    Hank Roberts says:

    Do follow the link; the journal, for example, tells you how they do most things. For example at

    ‘Accepted Articles’ have been accepted for publication and undergone full peer review but have not been through the copyediting, typesetting, pagination and proofreading process.

    Accepted Articles are published online a few days after final acceptance, appear in PDF format only (without the accompanying full-text HTML) and are given a Digital Object Identifier (DOI), which allows them to be cited and tracked. The DOI remains unique to a given article in perpetuity. More information about DOIs can be found online at

    Given that Accepted Articles are not considered to be final, please note that changes will be made to an article after Accepted Article online publication, which may lead to differences between this version and the Version of Record….

    (additional para. breaks added for readability — hr)

  9. 59
    James Cross says:

    #25 Stefan’s response

    Thanks but can you address how they used satellite data to fill in gaps in the Arctic which the satellite data does not cover?

    And also Chick Kellers point 4 in #41 about why wouldn’t the data before 1998 have the same under estimation problems?

  10. 60
    Kevin C says:

    James Cross: The satellite data hole is pretty small compared to the missing region of the arctic – only 5 degrees. UAH interpolates these regions, which should be fine over this range. The fact that the hybrid method gives better results than kriging for the south pole station is evidence that the interpolated satellite data still carries some information even at the poles, although less than for Vostok which is outside the hole.

    The reason why the effect takes over after 1998 is that that is when the Arctic warming really takes off. Look at the light blue curve in this figure from NASA/GISS.

    Chris Vernon asked about map projections. Most scientists seem to be well familiar with looking at cylindrical projections in papers, and there were a couple of other reasons: It allowed us to crosshatch the missing regions leaving more space in the colourbar while still allowing it to render in monochrome. It also allows the interesting high latitude cells to be visible in Figure 3. For our media materials however we’ve gone with Robinson (a compromise) and orthographic for the animations.

    [Response: Thanks, I was just going to say the same thing, Kevin. By my maths, the missing area (north of 85 N) is 0.2 percent of the Earth surface. -stefan]

  11. 61
    Icarus says:

    Temperature data for the Earth’s land surface is important, because that’s where we live, but it represents only a small part (3%?) of the total heat content of the climate system. Does anyone produce a data series which brings together ocean heat content, surface and lower troposphere data, ice melt etc. and combines them into one comprehensive ‘energy balance of the planet’ index?

  12. 62

    “If you trust the satellite data enough to fill in the gaps in the surface data then why just go with the satellite data by itself since it doesn’t have the gaps?”

    The answer is in the post: “…the satellites cannot measure the near-surface temperatures but only those overhead at a certain altitude range in the troposphere. And secondly, there are a few question marks about the long-term stability of these measurements (temporal drift).”

    Elaborating just a bit, the satellites don’t measure the same thing as thermometers do. Not directly–because the satellite sensors we’re talking about directly measure microwave radiation, which is then converted to temperature via calculation–and not categorically, because the temperature number you end up with doesn’t refer to one (sheltered) location two meters above the ground, but to a largish chunk of troposphere about (IIRC) 5 kilometers thick. That fact goes a long way toward explaining why the satellite datasets–UAH and RSS–show a lot more variability than the instrumental records do.

    So Cowtan and Way compared MacIntoshes to Granny Smiths–much better than MacIntoshes to Damson plums.

    More on the satellite data sets here:

    Note that geographical coverage extends over most, but not all of the Arctic–there’s a “pole hole,” but it’s only 5 degrees of longitude. (Some more geometrically/geographically astute person can tell you just what percentage of the entire Arctic, which conventionally extends down to roughly 66 degrees, that represents. But it’s a pretty small percentage.)

  13. 63
    jgnfld says:

    @41 Your comment makes little sense to me. WHY would variability be less now? What underlying mechanism are you proposing. The basic math here is simple: There is a trend line plus error. If you cherrypick timeperiods which start from local highs, it is terribly unsurprising that you see fewer higher highs in the immediately succeeding periods. This is a simple consequence of regression.

    Try cherrypicking from a local low (la Nina years around the same time) and you’ll find quite gigantic warming. Or, do the analysis right and look at all the data.

  14. 64
    Dick Dee says:

    I don’t understand what the fuss is all about. Estimates of global warming from model-based reanalyses incorporate many types of observations, including from satellites. These estimates include the effects of the Arctic and other “holes” in the conventional observing system. They have been shown to be consistent with traditional observation-based estimates (from GISS, NOAA, Hadley Centre) – see Simmons et al 2010 ( and successive BAMS State of the Climate issues since 2010. Why is there so much resistance to the use of modern reanalyses for estimating global temperature trends? Doesn’t it make more sense to use a physical model to interpret observations, rather than relying on simple statistical interpolation techniques? The same models used to predict typhoons many days in advance should be able to tell you something about the way the atmosphere behaves.

    [Response: Have a look at the paper – they also show the reanalysis trend for comparison, it is even larger than their optimal reconstruction. -stefan]

  15. 65
    Imback says:

    Kevin C, I haven’t read your new paper with Robert W yet, but I did watch your little companion movie. Well done, more authors should do that.

  16. 66
    G says:

    So why is warming slowing at those arctic stations, but not between them, (according this this study)?

    It’s worth noting that most arctic weather stations are located near the coast, and are highly influenced by the daily wind direction. Whereas the satellite data pixels at those same locations may have both a land and sea influence, as the pixels likely span both. So comparing the two may not be suitable, unless you adjusted which pixel you chose for each station day by day based on the wind. (And if the temperature data from the imagery is at an altitude so as to not be overly unfluenced by winds at a coastal location, that just begs another question in this comparison).

  17. 67
    Hank Roberts says:

    Zeke, thanks for 51. I was searching using “North Pole” there looking for weather stations nearest the Pole, and got fooled by retrieving the Alaska city by that name. Fooled me

    I’m guessing the other temperature records I turned up by the same search — data almost entirely from the 1950s — must be from drifting ice stations out in the Arctic Ocean.

    I’m still puzzled by the lack of data from the nuclear Navies during the Cold War years. Heck, the oil companies probably have some as well, I’d think.

    Which takes me back to wondering if the scientists who work closely with the Navies could possibly be benefiting from more data than they’re allowed to disclose (sigh).

    History teaches us that the grandchildren may — maybe — find out enough about what’s going on to make sense of today’s events.

  18. 68

    My apologies for my previous comment, I had not understood Peter Thorne right and the link goes to another paper on the same topic.

    On their homepage, the authors of this study also discuss previous studies. Worth reading.

  19. 69
    Blair Dowden says:

    I think this forum could be improved if inappropriate comments could be bounced back to the poster via the supplied e-mail address, with a reason for the rejection. Perhaps my first comment was poorly worded. If it had been bounced back I would have thought more carefully about expressing what I really wanted to say. But paranoia runs deep when somehow I have become an apologist for Roy Spencer. This kind of commentary diminishes the usefulness and credibility of this site.

    [Response: Ever wondered how we manage comment moderation in our spare time – even without bouncing back comments with explanations? -stefan]

    The background of the authors is unusual, which does not necessarily mean invalid. There is nothing wrong with wanting to know how this paper was written. It is impressive that an X-ray crystallographer (yes, not X-rated!) can produce this kind of work in his spare time. How much collaboration with other climate scientists was there, and how much does it take before ones name is added to the paper? I would just like to know more about how the scientific process actually works.

    As for the content, this video is a great summary. It is still hard to grasp how such a relatively small part of the Earth can raise the global average temperature by this much. I also do not understand how the Hadley re-calibration of sea surface temperature (HadSST3) plays into this, as much of the area in question is under sea ice. But as we keep increasing greenhouse gas levels, the additional forcing must be going somewhere. Maybe into the ocean, or the high Arctic, or maybe there is some negative feedback nobody knows anything about. In the long run I expect a rate of warming greater than 0.12 degrees C per decade.

    [Response: Note that the correction is very small – hundredths of a degree. It only makes a big difference to the trend because this is a short-term trend. Those should have been treated with caution anyhow, as the authors correctly point out. Short term trends are not robust. They change greatly when you change the start date from 1998 to 1999 for example, or when you slightly adjust the data within the error bounds as happened here. The “pause” should never have been a big deal, it captured the public imagination for no good reason. People confused noise with signal. -stefan]

  20. 70

    Tangential, but this enquiring mind wants to know how the heck “kriging” is pronounced. The obvious sources are here:

    The first is equivocal, but lists most of the leading possibilities. (In my head, the list of probable pronunciations forms a 2 x 3 matrix.) The second is helpful in that it suggests the pronunciation ought to be as closely as is reasonable in keeping with the pronunciation of the honoree’s name, Danie G. Krige–which I understand to be “KREEG-eh,” more or less.

    The matter has been discussed at length elsewhere, as a Google search will show quickly. But perhaps matters have moved on a bit from the date of some of those discussions.

    Opinions, information, anyone?

  21. 71

    If I understand it, the IPCC statement refers to the 1998-2012 trend, whereas Cowtan talks about the 1997-2012 trend.

    The piece implies these are one and the same. Is that right or is there a difference?

  22. 72
    Mal Adapted says:

    Blair Dowden at #11 and #20, are you the former President of Huntington University?

    I think your comment #20 is well said. The general inability of the lay public to evaluate the trustworthiness of scientific sources is ruthlessly exploited by the denial industry. I recommend Texas State Climatologist John Nielsen-Gammon’s presentation on scientific meta-literacy at the AGU conference last December (the linked page contains links to his text and power-point slides).

  23. 73
    Doug Bostrom says:

    Somebody (who said it is not important, right?):

    “So yes, the qualifications and experience of those who make specific claims of this kind do become important; and it would be naive to think otherwise.”

    No. What’s naive is failing to successfully classify and distinguish trivia versus substance. Ultimately, the only material of importance when it comes to assessing the worth and utility of a scientific publication are the claims and content of the paper and their relationship to other science. Author characteristics beyond the claims and content in the paper are useless gossip.

    “I would be interested to know what form of peer review the paper has undergone?”

    As opposed to personal gossip about authors, the journal in which a paper is found does offer some clues as to the paper’s worth, although exceptions abound. For those who simply can’t get their eyes and minds past peripheral matters and move on to reading and understanding the paper and its relationship to the greater world, here’s some information on the Quarterly Journal of the Royal Meteorological Society:

    Aims and Scope

    Editorial Board

    Author Guidelines

  24. 74
    Steve says:

    Hi everybody,

    The WUWT site has posted its response to the Cowtan paper. As I described above in my first-ever posts on a climate blog, I am a newbie citizen hoping to read various blogs to bolster my pre-existing concerns about AGW. My friend who is not persuaded told me to look at WUWT. My goal is to learn, and also to be able to show her posts on blogs that will persuade her, as well as myself.

    So… here is my impression. The postings on WUWT –for somebody like me, who doesn’t have the science background– look pretty persuasive. There are very specifically stated concerns about the paper, including images and animations. There is occasional “attitude” (which always drops credibility), but not that much.

    (One thing I am wondering: how do the guys on the WUWT blog find all the time they have for that blog? Not to get conspiratorial, but is it possible they are paid by some special-interest? I don’t want this to distract from the main question of the science, though.)

    I am hoping that this site can respond to their claims in ways that I can understand and compare.

    Now it might be that the scientists here feel there are better means to respond to their claims, or, have somehow learned a lesson that responding scientifically is not productive.

    But, that doesn’t help me, nor people like me, who are trying to persuade themselves or others, and are taking these blogs on face value.

    Finally, I will be disappointed if people here respond to my post with personal attacks. That will further soil this blog and reduce its credibility, and surely not help me become more educated.

  25. 75
    Susan Anderson says:

    Well, the back and forth, if prickly, did bring out some interesting information about skills and qualifications. Really interesting, thanks. I think it’s best to assume good faith, and one wants to be really careful with the /sarc if there’s any chance of the benefit of the doubt.

    It all comes back to what is knowledge. Anyone who pretends instead of doing the hard work is not knowledgeable, so admitting ignorance until one actually understands is the first step imnhso. As Gavin pointed out, climate science is a broad discipline and admits a variety of input, as long as it is honest and not bent on attack, which is always easy. One misses Stephen Schneider!

    captcha, too funny: scmpag pharisee!

  26. 76
    Ron R. says:

    It’s mid November in inland California and I’m looking at leaves on deciduous trees that should have fallen a month and a half ago, still green and going.

    No rain yet either.

    Yep, things are warming.

  27. 77
    Philip Cohen says:

    Just to be clear: I firmly believe in the reality of serious AGW, and am rather glad to be 64 and likely to be dead before the really nasty effects kick in. And I understand the paranoia that comes of dealing with climate liars almost daily for years.

    But the first thing I thought when I saw the bold paragraph was ‘I thought the “pause” was already explained by heat transfer to the deep oceans. How was this missed?’ And the first thing I thought when people started piling on Blair Dowden was ‘If you’re going to argue that denialists’ credentials are not necessarily relevant if they’re pontificating outside their field’–and that argument is often made, and I think it’s a good argument–‘then why not apply the same heuristic to extraordinary AGW papers?’

    I think that gavin and stefan’s initial response was polite, concise, and informative. Others, not so much. Yes, the content of the paper is what counts; yes, the authors’ expertise is in fact relevant; yes, the paper was peer reviewed in a respectable publication; yes, the conclusion was mooted before they put a number on it; but it’s not necessary to froth like a Watts when pointing this out. Blair D. strikes me as a concerned layman, not a concern troll. Jerry W @47, now….

    And because I found this conclusion so extraordinary, I’m going to wait a few months before I start using it in arguments. I wouldn’t be at all surprised if a few small details turn out to be questionable. Peer review is essential but it’s not the end of the process.

  28. 78
    Ron R. says:

    I should have mentioned, the temperature outside as I write is 88 F in the shade.

  29. 79
    Blair Dowden says:

    #72 Mal Adapted: No, I am not the former President of Huntington University. But thanks for the link about scientific meta-literacy (best summary here). This is an area of interest for me. Yes, ultimately only the content of the paper in question is what matters, but in the real world how many people can evaluate if HadSST3 is better than HadSST2, if it was correctly applied to the GISS data, and if the authors did their kriging correctly?

    I, like most others, can only rely on scientific meta-literacy to evaluate such a paper. Being in a peer reviewed journal is good but does not guarantee correctness (Lindzen gets published in peer reviewed journals, and his results are not always that great). And sorry, an author from outside the field (even a top scientist) is often not a good sign, but of course not necessarily. My original post was trying to do that kind of meta-analysis. I am sorry if I wrote it poorly and it looked like an ad hominem attack. I will be more careful next time.

  30. 80
    Jon says:

    @ Blair Dowden (#69)

    “I also do not understand how the Hadley re-calibration of sea surface temperature (HadSST3) plays into this, as much of the area in question is under sea ice.”

    Surely HadSST3 affects all the world’s oceans so the fraction covered by sea ice would be pretty small. A bit of Googling and checking Cryosphere Today tells me the world’s oceans have an area of 361 million square kilometres and the portion covered by sea ice is only between about 15 million and about 23 million square kilometers as it fluctuates annually.

  31. 81
    dhogaza says:


    “So… here is my impression. The postings on WUWT –for somebody like me, who doesn’t have the science background– look pretty persuasive.”

    That’s the point. They are meant to be persuasive to those not educated in the relevant scientific and mathematical fields. Apparently it is working …

  32. 82
    Steve says:

    Can somebody here respond point-by-point to Curry’s analysis (WUWT blog) of the Cowtan paper?

    Also, please respond to the claim on WUWT that satellite data is not reliable over the poles because they don’t really travel over them.


    [Response: Kevin Cowtan has responded to Curry here. Robert Way has responded here. And see also #86 below. -stefan]

  33. 83
    SecularAnimist says:

    Steve wrote: “The postings on WUWT –for somebody like me, who doesn’t have the science background– look pretty persuasive … is it possible they are paid by some special-interest …”

    Anthony Watts, who runs WUWT, has received tens of thousands of dollars in funding from the Heartland Institute, a global warming denial propaganda mill that is in turn funded by major carbon polluters. In short, he is paid to lie to you.

    All of his “persuasive looking” critiques of climate science have been thoroughly debunked and refuted many times over.

  34. 84
    Radge Havers says:

    Steve @ 74

    One thing I am wondering: how do the guys on the WUWT blog find all the time they have for that blog?

    Well for one thing, it takes less time to produce b.s. than actual science.

    I’m a fan of meta-literacy, but I think it takes perhaps a little more time and effort than is sometimes suggested. Tone trolling will not tell you much. Learning how the institutions of science work and how to spot rhetorical techniques, fallacious or invalid reasoning, and what amounts to simply poor reading comprehension will many times be all you need.

    When it comes to denialism and qualifications, there seems to be a signifigant hurdle in going from gassing on the intertubes to being expert enough to publish on the subject in respectable, peer-reviewed journals. Note that few deniers who are actual scientsts publish relevant material on the subject of climate — and of those who do, fewer still produce anything noteworthy.

  35. 85
    John Mashey says:

    1) Some grad students do very good work and Robert Way is hardly from outside the field, and it can be quite fruitful if computational methods get broader application in different fields.

    2) Whether an author team has PhDs and long publication records in X is not the issue, it’s the nature of the paper X the backgrounds.

    a) The paper is published in a serious journal and is an evolution of the current mainstream, often a refinement of mathematical technique better at extracting signal from noise, or combining disparate elements. The method may or may not be perfect, but the experts in the field think it’s good enough to take seriously, regardless of who wrote it.

    Such will likely stir more research, be refined, different people will publish variants and argue about them. Paleoclimate in general and the 1999 hockey stick specifically fit this. (After all, the latter did not suddenly overthrow Lamb(1965), which was long gone. (see p.15 of Strange Scholarship for a progression of curves among IPCC reports. MBH99 differs mainly from Bradley and Jones(1993), used in IPCC SAR mainly by having more proxies and applying additional math.

    After all, people have had very good reason to expect the Arctic to be warming faster, and see lots of evidence, but the challenge is to have better methods of filling in the holes. This is a common problem in many areas of science.

    b) The paper proposes a very different hypothesis to explain existing data. Again, experts will consider the merits, argue about it, some may get interested and do research. If the paper demonstrates knowledge of the literature, that’s a plus, and if the authors are known, it is likely to be taken more seriously, whether people buy it or not. My favorite example here would be Bill Ruddiman’s Early Anthropogenic hypotheses. (Note: for anyone attending AGU, Bill is giving the Tyndall Lecture on this, on Thursday the 12th.)

    c) The paper claims to overthrow a whole mesh of data and well-integrated data.
    It might be published in an odd venue, or show little knowledge of the literature or worse, cite as authoritative absurd or obsolete sources. For example, anyone positively citing E.G.Beck or Gerlich&Tseeuschner or almost anything at RC Wiki should raise red flags, as should anyone citing Lamb(1965/1982) except for history.

    If someone essentially claims to have repealed conservation of energy, or disproved Relativity using high school math or to have a better measurement of speed of light that says it is half what everything else says, then it’s barely worth thinking about, no matter who wrote it. Many times, those come from outside the field, as when Monckton’s endocrine surgeon claimed to have refuted Oreskes’ essay on consensus in Science(2004).

    In some sense, these cases aren’t very interesting, as lots of people who do not know a field think they know more than all the real experts. Every once in a while, someone who has published in the field (or a closely-related subfield) and ought to know better, suddenly starts claiming to overturn well-established results. A good example there would be the weird case of Murry Salby, starting in 2011 (See RealClimate comments 37, 42-81, and especially John N-G’s amusing comment. It turns out that Salby got an oral slot to talk about Antarctic ozone patterns … and with no notice gave a talk on his CO2 ideas. In this case, experts took a quick look, and then didn’t bother, even though Salby had a long track record in atmopsheric physics (not carbon-cycle or ice-core). For current discussions, try Stoat or WOTTS.

    Summary: experts look at the paper. Those of us who are less expert can look at credentials and track record of authors, but even better is to have found experts with credible histories and see what they think. All sorts of things can seem plausible if you’re not directly involved with the field.

  36. 86
    Robert Way says:

    Steve at 74,

    The key point in examining any supposed scientific criticism of a paper is to assess whether everything has been presented to you. The strongest portion of the Cowtan and Way paper is the cross-validation results and the comparisons with Arctic buoys on sea ice and in isolated locations. Any discussion that criticizes the paper (like the one at WUWT or at Climate etc) and yet does not mention either of these tests is unlikely to be reliable.

  37. 87
    Ray Ladbury says:

    Steve: “So… here is my impression. The postings on WUWT –for somebody like me, who doesn’t have the science background– look pretty persuasive.”

    OK, now here’s what I don’t understand. How in the hell can anyone find that looney bin persuasive? The only consistent tenet among the posts is “anything but CO2”, and that is NOT a scientific theory. The posts even contradict each other! If you look at the utter crap (CO2 snow, anyone? The stations project that never quite worked out? The reversal on Muller and BEST?). WTFUWT provides a useful service to education in climate science in the same way an insane asylum provides a useful service to the political process.

    Personally, I do not have a dog in this fight. I, too, find the claims of this paper surprising and think it deserves a lot of scrutiny. The work is certainly interesting.

    One question, Tamino has noted that the satellite datasets tend to be affected by ENSO much more strongly than the terrestrial series. Have the authors considered this?

  38. 88
    Susan Anderson says:


    Since all the hardworking scientists here have been subjected to continuous attacks, many of them underhanded and some of them pretty vile, it’s hard for them to be neutral about WattsUpWithThat. But consider the source. I get kind of tired of pulling up the same information, but in any other field you would try to find out who is best at the job and prefer their opinion. Claiming that RealClimate will be “further” tarnished does not inspire confidence in your objectivity. I suggest an objective reading through the archives here, with particular reference to the ClimateGate attack, for example.

    Many of the real experts are right here, and they run this blog. Try this:
    which leads to this:
    It’s a little out of date but you can click on the individual scientists’ links to find out their qualifications.

    You might search using your preferred search engine on any particular name, for example
    “Mike Mann cv” (curriculum vitae, or you could try bio for biography). The first result, pdf version, includes 42 single spaced pages of publications in top journals, honors, and the like. He’s a favorite target, because fake skeptics hate the temperature record which proves them wrong:

    Compare with Anthony Watts, a former weather presenter on a mission to discredit the best available science, with what appears to be a persecution complex, supporting by politics but not by reality. Have you been told that RealClimate censors? You really believe WUWT’s does not shut down dissenting voices in a big hurry? There’s plenty of evidence to the contrary if you will open your eyes and mind.

    You can also check some of the prominent figures in the mirror universe at Sourcewatch, which shows that most of them have connections to industry.

    For a more neutral source, here’s Wikipedia:

    After a long list of organizations in agreement, and a much shorter one of neutrals, it concludes with this:


    As of 2007, when the American Association of Petroleum Geologists released a revised statement,no scientific body of national or international standing rejected the findings of human-induced effects on climate change.

    Now I’m a layperson just like you, except I have a wide acquaintance with science and scientists, who are both smart and honest, which biases me in their favor.

    Don’t you think there’s something wrong with people who make it their mission in life to discredit the vast majority of working experts and expertise? How about you believe your five senses instead of these poorly supported assertions?

  39. 89
    Blair Dowden says:

    Stefan – Thanks for your response to #69. I appreciate how much work you must do to keep this forum going, and I would not want to add to the workload. The solution would be to get the software provider to attach a quick pop-up to the Reject button, you check the box that describes the problem (ad hominem, etc), and it automatically sends the e-mail. As for your second comment, I am sure you are right that we are all making a lot of fuss over what is mostly weather noise.

  40. 90
    Svet says:

    @62 Kevin McKinney – The answer is in the post…

    I don’t think that it is. I understand that the satellite data has limitations. My issue is that if you are concerned enough about those limitations that you use the surface data instead then isn’t it a bit weird to then use that satellite data (with all of its limitations) to fill in the holes in the surface data?

    Put another way, if the satellite data is robust enough to be usable to fill in holes in the surface data then is it not robust enough to be used and trusted in its own right?

    As James Cross mentioned above, the satellite data shows the “pause” and yet it is now being used to show that there is no “pause”. There just seems to be something illogical about that. Am I missing something?

  41. 91
    Hank Roberts says:

    Could we talk about the data and analysis?

    It sounds from the first post like most of the difference between before and after taking cognizance of the change in the global average — is to say, oh, good, that makes more sense than what we were getting.

    Is that even close?

  42. 92
    Steve says:


    Thanks all for your responses to some of my questions. The thing that would most help is what I asked for in #82, a point-by-point response to the WUWT assessments of the Cowtan paper. It would be really great if somebody could give that a whack. Robert Way in #84 did give a hint in this direction, but it did not touch on the points that Curry raised. (This is the last time I will ask for it.)

    Telling me that the guys there are unqualified, etc, doesn’t really help me. Nor does telling me that what they post is often inconsistent.

    I am looking at this current topic, the Cowtan paper, as a moment where I could be locked into my conviction that skeptics are generally full of it, or where they could succeed in introducing doubt in my mind. So far, sadly, they have succeeded in the latter. And if they can succeed in doing that with me, a person who has been an ardent environmentalist for 40 years, then I hate to think about less committed people.

    Again, I am looking for concrete ammunition to persuade my friend (and other agnostics/skeptics).

    If I can point to a blog post on WUWT that looks like careful analytic thinking objecting to a mainstream paper, but can be revealed as scientific misconception or misinformation, that would be a huge win.

    Thanks again.

    If it turns out that you guys can’t do this I guess I’ll have to continue reading contradictory blogs and over time try to form a judgment.

    [Response: Kevin Cowtan has responded to Curry here. Robert Way has responded here. -stefan]

  43. 93
    Dave123 says:

    @89 – Svet You seem to have dismissed Gavin’s concise note that that Satellite record only shows a pause if you cherry pick 1998 as the start date. I’ve done my own playing around at wood for trees, and I don’t think the UAH data there shows a pause at all. Break the data into 1979 to 199x and 199x to 2013 and see what i mean.

    Now for Steve-

    I’m seeing what I regard as a suspicious synchrony in concerns about tone across a number of boards, so you won’t mind I hope, if I’m not immediately solicitous towards your notions of civility.

    So let me tell what I see especially from people without any science or math chops:

    First there is a pure bit of grammar school beat up on the smart kid going on here. The motive seems nothing more or less than to get some feeling of triumph over all those smart guys with Ph.D.s who do all this complicated stuff we can’t understand. The result is that it doesn’t matter how many times a myth is debunked, how many stakes we put through a zombie myths heart, none of that counts against any possible thrill that one of those “too-smart-for-his-own-good-and-he’s probably a commie too” is somehow shown up. You really can’t talk with people like that. The question is, what tactics are effective in demonstrating to the reading public what’s going on, and that having some unresolved envy issues with smart kids isn’t how you figure out whether the science is right.

    Second, far too much of this starts with ideology, as if the oceans care about the politics of people measuring the heating, the rise in sea, the fall of pH etc.

    And from our side, we worry about the Serengiti Strategy being applied to distinguished scientists such as Mike Mann, and a lack of good faith when the same voices repeatedly do not engage scientific evidence and reasoning and simply repeat the myth again.

    Anyhow, thanks for the opportunity to put forth this meme: That a lot of this is a bunch of goofs trying to gang up on the smart kid at recess.

  44. 94
    deconvoluter says:

    RE: #12. (Vaguely)

    The extreme confidence of political contrarians. Are they taught to act?

    I went straight from reading this, to watching the latter part of “Question Time” on BBC 1 which ran from 10.35 PM to 11.35PM. It is probably still available on BBC’s I Player.

    By coincidence they were discussing Typhoon Haiyan and climate change in general. The team included Nigel Lawson, who invoked the IPCC for support, which he had previously tried to discredit. This is exactly the same tactic as that used by his ex-colleague Peter Lilley over the Arctic. Lawson told the audience that there was no evidence at all, that extreme storms were becoming more intense , and repeated the mantra that there had been no warming for 15 years. He was well prepared and chose his words carefully in such a way as to mislead. The good news was that he was received with skepticism, but the bad news was that the replies were rather muddled. Lawson’s extreme confidence appeared to throw the team off balance including even Ed Davey , the Liberal Democrat minister(second in seniority in the UK government on climate change policy) who was surprisingly insecure about the details apart from adopting some words of appeasement (“Lawson had written a good book on the subject” which Ed happened to disagree with).

    Very recently I watched an earlier version of Question Time in which Lawson’s role was taken by the Daily Mail’s Peter Hitchens who like Peter Lilley and Nigel Lawson adopted a similar pose of confidence in taking an even more extreme position.

  45. 95
    Robert Way says:

    Ray at 87 –

    “One question, Tamino has noted that the satellite datasets tend to be affected by ENSO much more strongly than the terrestrial series. Have the authors considered this?”

    I believe that is probably related to the sensitivity of the remote sensing systems to precipitation and clouds in the atmosphere. A good place to start is Weng et al (2013) which has a very important conclusion. The ENSO impact on TLT trends is an important issue and one that should be investigated but in the same context it should be noted that the TLT data is only used as a proxy for surface temperature and cross-validation shows it performs well in this regard. In fact, it may be the case that by including the Arctic we are reducing the dependency of global temperature on ENSO as opposed to in the initial Met Office record.

    Weng et al.(2013). Uncertainty of AMSU-A derived temperature trends in relationship with clouds and precipitation over ocean. Climate Dynamics.

  46. 96
    Svet says:

    @92 Dave123 – Thanks. Did somehow miss that reply. Thanks also for the link to

  47. 97
    Doug Bostrom says:


    Here’s a simple and easy exercise. Use the search facility at upper right, on the term “newbie” or “beginner” or various synonyms claimed by self-professed neophytes. You’ll find many comments in the results. Follow the evolution of those conversations.

    Originality is preciously rare.

  48. 98
    Charles says:

    I’d like to chime in on the value of the WUWT site, on my way over there to check out the analysis of the Cowtan and Way paper, I ran across this posting titled “What makes the warmist-skeptic fight go on and on?” In that piece, I found this gem:

    “Specifically, the skeptics use declarative, as in “this will”, “this shall” or “this does”, and, of course, its negative equals. The warmists use conditionals, i.e. words like “could” or “should” or “may” or “might” that indicate undefined probabilities and, in truth, possibilities, things that are determinable only after the fact.

    “The use of conditionals after 25 years is remarkable (here I make a declarative statement). Despite all the models and claims of correlation/matching of observation, we still have no “does”, “shall” or “will” in the IPCC or other CAGW programme. The dangers and fears are in the distant future, discussed only as emerging from the present, but still only becoming obvious in some, never-close-to-today, tomorrow.”

    And this from someone who claims some authority as to why the “skeptics” and climate scientists disagree! I had a good laugh over that bit. It is evident that this person hasn’t much of a clue of how science works or of the epistemology of science. How can anyone take a site that posts stuff like this seriously?

    My impression of WUWT is that they use the “throw enough mud at the wall and see what sticks” approach in their opposition to climate science. I see a lack of any comprehensive theoretical framing, not to mention a lack of empirical support. Instead, what i have observed is a hodge podge of stuff, some of it contradicting other stuff that is posted there. A real dog’s breakfast. (So sorry to mix up the metaphors–I couldn’t resist.)

  49. 99
    Jane Jackson says:

    Building on comments #83 and 88: an insightful article that you can download in pdf is “Cool Dudes: The Denial of Climate Change among Conservative White Males in the United States”. This is a 2011 paper by sociologists Aaron McCright and Riley Dunlap, published in Global Environmental Change. The authors explore social and psychological reasons why conservative white men are especially prone to climate change denial.

    QUOTES FROM THE ARTICLE [I omit references, for ease of reading]:

    Our data come from the Gallup Organization’s annual environment poll, conducted each March in anticipation of Earth Day (April 22). [They used data from 2001 – 2010. jj]

    … significantly greater percentages of conservative white males than of all other American adults report denialist views. For instance, while 29.6% of conservative white males believe that the effects of global warming will never happen, only 7.4% of all other adults believe so. Also, 58.5% of conservative white males but only 31.5% of all other adults deny that recent temperature increases are primarily caused by human activities.

    … a greater percentage of conservative white males (30.4%) than of all other adults (18.0%) report that they understand global warming very well. … conservative white males tend to assert somewhat greater personal understanding of global warming than do other adults. This, of course, seems an untenable self-assessment, given that conservative white males are more likely than are other adults to reject the current scientific consensus. …

    Conservative think tanks, conservative media, corporations, and industry associations (especially for the fossil fuels industry) — domains dominated by conservative white males — have spearheaded the attacks on climate science and policy from the late 1980s to the present. The results presented here show that conservative white males in the general public have become a very receptive audience for these efforts. When mobilized, these conservative white males may constitute a key vector of climate change denial in their own right via their online and offline social networks and through participation in various protest and campaigning events.
    Since the mid-1990s, organized climate change denial has diffused from the US to other Anglo nations with established conservative think tanks that promote free-market conservatism and front groups promoting industry interests, most notably Great Britain, Canada, Australia, and New Zealand. This spread of climate change denial has been driven to a significant degree by key actors — and their resources, strategies, and tactics — in the U.S. climate change denial machine. …

  50. 100
    Hank Roberts says:

    Steve, you should do the point by point thing yourself.
    Seriously. Copy the point, open Scholar, paste it in.
    The ‘oogle has a better and better “natural language search” and you can refine what you see. Pick just 2013 and read a few pages of the results on the point and decide if it’s worthwhile.

    When you can say you looked up a point and got an opinion whether it was a good one or not — someone may get interested enough to help you if you’re stuck. Otherwise you end up “debating” — which isn’t science.

    Better — watch for Curry’s paper on the subject when and if it comes out. See if what gets published matches the blog, or not. Stuff that attracts blog readers is often very different from what’s worth publishing as science.

    You wrote

    … succeed in introducing doubt in my mind. So far, sadly, they have succeeded

    You sound there as though you think doubt is a bad thing.
    Au contraire.

    Science _exists_ to introduce doubt, then to find ways to do something that could convince you that your idea is wrong. That’s progress!

    How it works

    Asking for point by point responses? That’s homework help. You start; then others will work along with you, if what you find is interesting.

    40 years an ‘environmentalist’ — and did you take Ecology 101?
    Statistics 101? Those classes open up the world beyond anything else. Most ‘environmentalist’ folks