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Are the CRU data “suspect”? An objective assessment.

Kevin Wood, Joint Institute for the Study of the Atmosphere and Ocean, University of Washington
Eric Steig, Department of Earth and Space Sciences, University of Washington

In the wake of the CRU e-mail hack, the suggestion that scientists have been hiding the raw meteorological data that underpin global temperature records has appeared in the media. For example, New York Times science writer John Tierney wrote, “It is not unreasonable to give outsiders a look at the historical readings and the adjustments made by experts… Trying to prevent skeptics from seeing the raw data was always a questionable strategy, scientifically.”

The implication is that something secretive and possibly nefarious has been afoot in the way data have been handled, and that the validity of key data products (especially those produced by CRU) is suspect on these grounds. This is simply not the case.

It may come as a surprise to some that the first compilation of world-wide meteorological data was published by the Smithsonian Institution in 1927, long before anthropogenic climate change emerged as an important issue (Clayton et al., 1927). This volume is still widely available on the library shelf as are updates that were issued periodically. This same data collection provided the foundation for the World Monthly Surface Station Climatology, 1738-cont. As has been the case for many years, any interested party can access this from UCAR ( and other electronic data archives.

Now, it is well known that these data are not perfect. Most records are not as complete as could be wished. Errors periodically creep in and have to be identified and weeded out. But beyond the simple errors of the key-entry type there are inevitably discontinuities or inhomogeneities introduced into the records due to changes in observing practices, station environment, or other non-meteorological factors. It is very unlikely there is any historical record in existence unaffected by this issue.

Filtering inhomogeneities out of meteorological data is a complicated procedure. Coherent surface air temperature (SAT) datasets like those produced by CRU also require a procedure for combining different (but relatively nearby) record fragments. However, the methods used to undertake these unavoidable tasks are not secret: they have been described in an extensive literature over many decades (e.g. Conrad, 1944; Jones and Moberg, 2003; Peterson et al., 1998, and references therein). Discontinuities may nevertheless persist in data products, but when they are found they are published (e.g. Thompson et al., 2008).

Furthermore, it is a fairly simple exercise to extract the grid-box temperatures from a CRU dataset—CRUTEM3v for example—and compare it to raw data from World Monthly Surface Station Climatology. CRU data are available from One should not expect a perfect match due to the issues described above, but an exercise like this does provide a simple way to evaluate the extent to which the CRU data represent the underlying raw data. In particular, it would presumably be of interest to know whether the trends in the CRU data are very different than the trends in the raw data, since this could be taken as indication that the methods used by CRU result in an overstatement of the evidence for global warming.

As an example, we extracted a sample of raw land-surface station data and corresponding CRU data. These were arbitrarily selected based on the following criteria: the length of record should be ~100 years or longer, and the standard reference period 1961–1990 (used to calculate SAT anomalies) must contain no more than 4 missing values. We also selected stations spread as widely as possible over the globe. We randomly chose 94 out of a possible 318 long records. Of these, 65 were sufficiently complete during the reference period to include in the analysis. These were split into two groups of 33 and 32 stations (Set A and Set B), which were then analyzed separately.

Results are shown in the following figures. The key points: both Set A and Set B indicate warming with trends that are statistically identical between the CRU data and the raw data (>99% confidence); the histograms show that CRU quality control has, as expected, narrowed the variance (both extreme positive and negative values removed).
Comparison of CRUTEM3v data with raw station data taken from World Monthly Surface Station Climatology. On the left are the mean temperature anomalies from each pair of randomly chosen times series. On the right are the distribution of trends in those time series and their means and standard errors. (The standard error provides an estimate of how well the sampling of ~30 stations represents the full global data set assuming a Gaussian distribution.) Note that not all the trends are for identical time periods, since not all data sets are the same length.

Conclusion: There is no indication whatsoever of any problem with the CRU data. An independent study (by a molecular biologist it Italy, as it happens) came to the same conclusion using a somewhat different analysis. None of this should come as any surprise of course, since any serious errors would have been found and published already.

It’s worth noting that the global average trend obtained by CRU for 1850-2005, as reported by the IPCC (, 0.47 0.54 degrees/century,* is actually a bit lower (though not by a statistically significant amount) than we obtained on average with our random sampling of stations.

*See table 3.2 in IPCC WG1 report.

Clayton, H. H., F. M. Exner, G. T. Walker, and C. G. Simpson (1927), World weather records, collected from official sources, in Smithsonian Miscellaneous Collections, edited, Smithsonian Institution, Washington, D.C.

Conrad, V. (1944), Methods in Climatology, 2nd ed., 228 pp., Harvard University Press, Cambridge.

Jones, P. D., and A. Moberg (2003), Hemispheric and large-scale surface air temperature variations: An extensive revision and an update to 2001, Journal of Climate, 16, 206-223.

Peterson, T. C., et al. (1998), Homogeneity adjustments of in-situ atmospheric climate data: a review, International Journal of Climatology, 18, 1493-1517.

Thompson, D. W. J., J. J. Kennedy, J. M. Wallace, and P. D. Jones (2008), A large discontinuity in the mid-twentieth century in observed global-mean surface temperature, Nature, 453(7195), 646-649.

242 Responses to “Are the CRU data “suspect”? An objective assessment.”

  1. 151
  2. 152
    Jon H says:

    63: “Truly..truly…the kind of remarks such as “the Post drifts closer and closer to the Times with each passing week…” nonsense leads more and more people to believe that politics is inherent in the AGW position. Stick to the science and leave out the politics. The more you do this, the more impetus you give to the skeptics.”

    The WaPo’s shift right has been longstanding, and not just on climate issues. They’ve been pandering to climate skeptics lately, but they’ve been pandering to neocons for far longer. Stories that questioned the threat posed by Iraq got stuffed inside the paper instead of front-paged.

  3. 153
    Gerry Morrow says:

    Eric, good article, but it leaves a few dangling questions surely. The questions are why, if the data and adjustments were reasonable and verifiable, did the CRU repeatedly refuse to tell McIntyre where it was? Secondly they are now saying they’ve lost the original data, but always assuming they had, why didn’t they tell him they’d lost it at the first request? Finally, why the threats, joking or otherwise, to delete the data if it was going to get into McIntyre’s hands? It seems an awful lot of trouble to go to if you are convinced your data is spot on and clean as a whistle.

    If Muir Russell is half the investigator I think he is he’ll be asking these questions because, whether you like it or not, your work is being used to decide policies which will affect everyone in the world if implemented and there are some serious gaps in the logic as to why McIntyre was given what we Brits call “the bum’s rush”.

  4. 154
    CM says:

    OK, stupid question: why did they split the data into two sets? To make something stand out more clearly?

  5. 155

    Can someone please explain to me why the major source of greenhouse gases is rarely, if ever mentioned in any commentary regarding climate change? There is much talk about renewable energy, better insulated buildings, energy efficient lighting, etc. but there is not much dialogue on the biggest villain of all.

    The largest source of greenhouse gases is from the raising of livestock for human consumption which, according to very reliable source ( Worldwatch Institute ) accounts for most ( 51% ) of all green house gas emissions!

    Are we that addicted to consuming animal flesh that we choose to not even discuss this issue? Is the meat industry lobby so powerful that they can continue to hide and down play this now well know fact? Why are people still eating meat when it is so very bad for their health and the health of their planet when there are so many delicious veggie alternatives?

    The fact is that if everyone on our planet changed their diet from an animal to a plant based diet we could eliminate MOST of the greenhouse gases entering our atmosphere which are quickly condemning virtually all living beings on this planet to certain death as the planet will soon no longer be able to support human, animal or plant life.

    I feel that we must focus on what is clearly the largest emitter of greenhouse gases if we have any hope at all of saving our world! Bottom line: we must stop eating meat immediately or our destiny will be sealed! Please read this article and do everything possible to ensure that our planet survives the biggest threat we have ever known!

  6. 156
    Hank Roberts says:

    > alantrer 16 December 2009 at 12:20 pm
    > there we have it …
    > Homogenization adds no … value

    Where did you get that? Are you joking to the skeptics?

    When I search on the words you use I find many references on why and how data is worked over to make it usable.

    Here’s one example:

    Temporal Homogenization of Monthly Radiosonde Temperature Data. Part I: Methodology July 2002

    Historical changes in instrumentation and recording practices have severely compromised the temporal homogeneity of radiosonde data, a crucial issue for the determination of long-term trends. Methods developed to deal with these homogeneity problems have been applied to a near–globally distributed network of 87 stations using monthly temperature data at mandatory pressure levels, covering the period 1948–97. The homogenization process begins with the identification of artificial discontinuities through visual examination of graphical and textual materials, including temperature time series, transformations of the temperature data, and independent indicators of climate variability, as well as ancillary information such as station history metadata.

    To ameliorate each problem encountered, a modification was applied in the form of data adjustment or data deletion. A companion paper (Part II) reports on various analyses, particularly trend related, based on the modified data resulting from the method presented here.

    Application of the procedures to the 87-station network revealed a number of systematic problems. The effects
    of the 1957 global 3-h shift of standard observation times (from 0300/1500 to 0000/1200 UTC) are seen at many stations, especially near the surface and in the stratosphere.

    Temperatures from Australian and former Soviet stations have been plagued by numerous serious problems throughout their history. Some stations, especially Soviet ones up until 1970, show a tendency for episodic drops in temperature that produce spurious downward trends.

    Stations from Africa and neighboring regions are found to be the most problematic; in some cases even the character of the interannual variability is unreliable. It is also found that temporal variations in observation time can lead to inhomogeneities as serious as the worst instrument-related problems.

    Just an example worth a look for anyone who is starting off by eyeballing the raw data files — which is what these people did. You could do worse than to follow their exact example, documenting everything you see and what you do about it. In fact you might get a publication out of it!

  7. 157
    Charles Copeland says:

    @cyclox, No 134 (‘The pushback continues’)

    Cyclox, I’ve had a brief look at the Daily Express’s ’100 reasons why’ and, yes, most of it is the usual rubbish. But one shouldn’t over-egg the pudding.

    One example: Reason 46 runs “The IPCC alleges that “climate change currently contributes to the global burden of disease and premature deaths” but the evidence shows that higher temperatures and rising CO2 levels has helped global populations”.

    Michael Page’s refutation in the New Scientist (“50 reasons why global warming isn’t natural”) states:

    Incorrect. Excessive heat during summers is already killing more people than are being saved by milder winters.“, with a link to another New Scientist article entitled “Global warming will increase world death rate”. This article in turn refers to a contribution to the journal “Occupational and Environmental Medicine” with the heading “Temperature, temperature extremes, and mortality: a study of acclimatisation and effect modification in 50 US cities”.

    There is no reference in the abstract of the peer-reviewed OEM article to the ‘world death rate’ and one can hardly extrapolate from 50 US cities to the 7 billion inhabitants of the entire planet. Frankly I have no idea as to whether the net death rate (lives saved due to milder winters minus lives lost due to hotter summers) is positive or negative but Page’s counter-argument certainly doesn’t convince, since it is based on a totally miscontrued interpretation of an original peer-reviewed article.

    There are enough sound arguments to defend the facts of AGW. Why add spurious ones?

  8. 158
    Rando says:

    92 and 116: Take a look at today’s temps in Alert (-7C) and Eureka (-11C) in Nunavut, way up north in northern Canada. They’re forecasting +5 and rain in Iqaluit on Friday – that’s on Baffin Island. The Arctic sea ice is going to start melting if that keeps up. Mind you, it’s -31C over here in Yellowknife today, so you could just say….interesting weather we’re having today, isn’t it?

  9. 159
    Louise D says:

    #134. I’ve just looked at the Daily Express article again, it’s so bad it’s difficult to read all 100 reasons “why clinate change is natural”, but nearly half bear no relation to the title – such as ‘Despite the 1997 Kyoto Protocol’s status as the flagship of the fight against climate change it has been a failure’. The sad thing is that many people in Britain read this paper and are more likely to belive what it says than beleive any science based arguments. the refutation of the first 50 points is in the New Scientis which I would guess has a much smaller readership Just one more examlpe of the Express’s reasoning; point no.89 “It is a myth that CO2 is a pollutant, because nitrogen forms 80% of our atmosphere and human beings could not live in 100% nitrogen either: CO2 is no more a pollutant than nitrogen is and CO2 is essential to life.”

  10. 160
    David B. Benson says:

    Bill DeMott (118) — Thank you.

  11. 161
    rb says:

    In response to #92, how long have you been collecting data?

    Here are some temperature data (F) for a few widely spaced northern North America locations:

    Town 1970s 1980s 1990s 2000-2006
    Eureka, Nunavut -4.9 -3.7 -1.8 -.5
    Norman Wells, NWT 21.1 22.2 22.7 23.4
    Nome, Alaska 25.5 27.9 a 28.3
    Churchill, Man. 18.9 19.6 20.1 21.4
    Goose, Bay (NFL) 30.7 31.3 31.0 33.4

    a-incomplete data

    Do you see any trends? Although I haven’t updated since 2006, the values for 2000-2009 aren’t going to change significantly from 2000-2006.

    If you look at the 2009 average data up to this point for towns in northern North America and northern Europe, the vast majority have temperature averages above the long-term averages.

    Roger Blanchard

  12. 162
    Andy Gates says:

    @134 cyclox, it took me 90 minutes to rip all hundred apart – it’s a fun project for a quiet evening. I analyzed the flaws in that “100 reasons” – classing them fairly arbitrarily – and fully three-quarters are ideological, or straightforward lies, or smears. The rest is a smattering of crank references, misquotes, tired canards, junk science and the like.

    Their method, this “100 reasons” is the standard Gish Gallop: lots and lots of guff, which takes time to take apart, so in a limited setting you get 100 presented, maybe a couple refuted, and 98 “what ifs” left to confuse the public. But it’s all ideologically driven, there’s no damn science in it anywhere. It’s “100 lies we want you to believe”.

  13. 163
    kasphar says:

    ZZT@ 49

    This might be an example of what you are talking about.
    In my town there are two weather stations within 300m of each other. One is a manual w/s and the other an automatic w/s. The MWS is near a tarred road with buildings close by. The other is in the middle of a grassed oval with some buildings 60-70m away but only on the western side.
    The MWS can record maximum temps up to 1.0C higher than the AWS.
    Go to

  14. 164
    TH says:

    Looks like December will be the coldest on record in the US, after the third coldest October.

    “Whoever undertakes to set himself up as judge in the field of truth and knowledge is shipwrecked by the laughter of the Gods.” – Albert Einstein

  15. 165
    Thor says:

    # 100
    [Response: .... The adjustments are actually very close to Gaussian centered on zero in the GHCN procedure.... -gavin]

    Does this Gaussian distribution have a constant average value over time?

  16. 166
    Completely Fed Up says:

    “Homogenization adds no statistically relevant value”

    Uh, you misspelled “bias”.

    Homogenisation adds no statistically relevant BIAS.

  17. 167
    Ray Ladbury says:

    Alan Trer says: “Well there we have it then. Homogenization adds no statistically relevant value in deriving the global mean temperature. Do the science a favor by presenting a simpler argument using just the raw data.”

    Well, except if they didn’t make corrections you’d claim it was all the Urban Heat Island or some other artifact. Remind me again why scientists should give a tinker’s damn what you think?

  18. 168
    Completely Fed Up says:


    “#99 And then Ian George would require the calibration tests of the thermometers. And the manufacturing report.

    Which should be included in any report.”

    Why? The thermometers are made at a factory.

    They are sold.

    Do you have a thermometer?

    Do you have the tech spec for it?

    No, I doubt you have.

    And so I guess you’ll say merely because they aren’t available (despite not being raw data or source code or models or any of the hundred other things you’ve decided MUST be made available) that this PROVES that the data is wrong.

    Tell you what.

    Make your own observing network (pay for it yourself, I don’t want my taxes to pay for your insanity). With hookers and blac k jack if you like.

    Then while we work with what our current network shows (that we need to avoid CO2 production) you can go on and build up the case for the evidence that there’s nothing to worry about.

    Please. Remember to keep all station logs, all emails on any subject, all invoices (you may have paid a company with biases on AGW for their kit) and all other information we’ll discuss when you’re ready to report.

    Then use that data (if you can PROVE it’s right) to show we should go back to Oil/Coal which, since we haven’t burned any, is still sitting nicely under ground.

  19. 169
    Ray Ladbury says:

    DVG@131, As my puppies are now dogs and fully housebroken, I now have no need of the Wall Street Journal. Thanks all the same.

  20. 170
    lgp says:

    correcting my typo correction (again)

    in post my post awaiting moderation, I have a typo

    That you find the same answer as CRU only prove’s Pielke’s judgement that Phil Jones’ assertion that CRU isn’t independent of GISS et al is TRUE.

    should read

    That you find the same answer as CRU only prove’s Pielke’s judgement that Phil Jones’ assertion that CRU IS independent of GISS et al is FALSE.

    [Response: What? GISS has nothing to do with the analysis in this post. Or are you simply saying "both GISS and and CRU used temperature data from the same planet?"--eric]

  21. 171
    aH1GH3Rpower says:

    How do we know that the data your using to back up the CRUs hasnt been tampered with aswell? Such as in the New Zealand incident Also im sorry but this talk of not having time to reinvent the wheele with only 60 some testing stations doesnt seem like enough to claim to be an objective assesment of the planets temp trends. And with the policy solution of classifying Co2 as a polutant and taxing it? The gas that every plant form on this planet uses to breath, which every animal atleast indirectly uses to eat, and who inturn we eat just seems a little irresponsible.

  22. 172
    jonesy says:

    [Response: What? GISS has nothing to do with the analysis in this post. Or are you simply saying "both GISS and and CRU used temperature data from the same planet?"--eric]

    So do you mean CRU and GISS (and NOAA) all use the same station raw data, but their temperature results are independent because they all process it independently?

    [Response: Bingo! (Actually, I doubt they use exactly the same raw data -- no doubt there are some differences -- but the overlap is obviously going to be huge).--eric]

  23. 173
    Paul says:

    The results of the GW debate have become intimately tied to what is potentially the largest international treaty for at least a generation. To pretend at this point that the science has not been politicized strikes me as quite naive.

  24. 174
    Ray Ladbury says:

    TH says “Looks like December will be the coldest on record in the US, after the third coldest October.”

    Uh, dude, ever look at a map? Did you know there are whole countries outside the US?

  25. 175
    Doug Bostrom says:

    aH1GH3Rpower says: 16 December 2009 at 7:02 PM

    “How do we know…”

    Check under your bed first, that’s my advice. Who knows what’s going on down there?

  26. 176
    jonesy says:

    [Response: Bingo! (Actually, I doubt they use exactly the same raw data -- no doubt there are some differences -- but the overlap is obviously going to be huge).--eric]

    Thanks, I think that’s information that I and a lot of people are confused about.

    So, if anyone wants to find the “raw data” for a certain station, it’s my understanding that some is publicly available but some is proprietary. Is that correct? Is the publicly available data all at one site, or at various sites?

  27. 177
  28. 178
    sHx says:

    DEB(#84) said, “I was talking here about polar cities to save survivors in 2500 AD and you all thought I was nuts. What do you think now? We are getting closer to that time….”

    BPL(#103) replied, I think you’re nuts.

    Sorry, I couldn’t resist. But A) in 2500, there won’t be a North Pole, and B) the survivors won’t have the capital, infrastructure and functioning economy enough to build a domed city in Antarctica.

    Sorry, I couldn’t resist either. I am very curious to know why BPL, a “SF action adventure” writer (according to his website) and a frantic commenter on this blog, be so pessimistic about the possibilities for human habitation by 2500 AD.

    A) Why will there not be a North Pole by 2500 AD? Is it because it will float on dwindling ice floes and eventually go extinct like polar bears? Will the gyroscopes only show the South Pole by 2500 AD? The questions are cheeky but fair to ask, considering the hyperbolic claim that brought them forth: that the AGW will make the North Pole disappear! No, BPL, “polar cities” in the North won’t be established on the pole, but on the vast, uninhabited polar lands around it. And the North Pole isn’t going anywhere soon, climate change or not. Are you nuts?

    B) Why shouldn’t a domed city in Antarctica be possible? A civilian population centre -most probably a tourist resort for the fabulously rich and eccentric- is already well within the realms of the present day capital and technology. In fifty or a hundred years, towns and and cities with hundreds of domes may spring up, especially if valuable resources like gold and diamond are found. The existing Antarctic Treaty is written on ice, not on stone. And like Rome, Antarctic polar cities won’t be built in a day.

  29. 179
    David Horton says:

    #164 TH – “Looks like December will be the coldest on record in the US, after the third coldest October.” Yeah, uh, record HOT November temps in Australia. This is the southern hemisphere, you will recall, where we are coming into another frighteningly hot summer with bushfires, yet again, burning ferociously. Guess it’s cold up north, eh TH, who’d a thunk it?

  30. 180
    Phil Scadden says:

    aH1GH3Rpower – and do you realise that “NZ incident” was trumped up garbage easily refuted by NIWA. (See for more discussion). See here for more on Hokitika.

    And for goodness sake – if you think you can make global warming go away by making unfounded attacks on the station record, how then do you explain sealevel rise (, or the satellite MSU-LT trends? And the problem with CO2 is rapidly releasing Gtonnes of carbon sequestered over millions of years. The natural CO2 cycle isnt relevant. If your stance is that you doubt the science because you find suggested solutions (liking taxing carbon so carbon alternatives are sought instead) unpalatable, then please suggest a better way to reduce CO2 in the atmosphere. I’ll back any solution that actually creates a reduction but judging facts on the basis of your biases about solutions seems intellectually dishonest.

  31. 181
    Dale says:

    John #137, for the most part I agree. The consertive Roscoe Bartlett is at forefront of peak oil in the congress and is a strong supporter of the science of AGW. When I refer to right wingers I’m talking about people who have perverted the meaning of a conserative and turned it into reactionary. These are people who are guided by idiology and if facts fly in the face of what they believe they simply put their fingers in there ears, close their eyes and yell, “Honey, turn on Rush….quick!” They are people who view the world through a soda straw and are up to their hips in dogma and don’t pocess two cents worth of pragmatism. They have the least amount of scientific credentials yet they want to be the ones who tell us what the science says. If Inhofe and all like minded people were all in one world, would one of them contemplate themselves as a virus?

    By the way, you’re one of the people I always read and have great respect for your thoughts.

  32. 182
    Steve Fish says:

    Comment by trrll — 16 December 2009 @ 1:18 PM:

    Thanks! You describe how I was trained, and how I trained my students. Those outside of science sometimes have a hard time understanding this embedded ethic.


  33. 183
    Molnar says:

    When you reorder some of the items on that Daily Express list, it comes out a bit funny…

    “9) Leaked e-mails from British climate scientists – in a scandal known as “Climate-gate” – suggest that that has been manipulated to exaggerate global warming

    42) The Met Office asserts we are in the hottest decade since records began but this is precisely what the world should expect if the climate is cyclical”

    So the recent warming has been exaggerated, unless the climate is cyclical, then it wasn’t…

    “17) The science of what determines the earth’s temperature is in fact far from settled or understood.

    7) The 0.7C increase in the average global temperature over the last hundred years is entirely consistent with well-established, long-term, natural climate trends.

    22) There is strong evidence from solar studies which suggests that the Earth’s current temperature stasis will be followed by climatic cooling over the next few decades”

    Obviously, we don’t know what determines the temperature of the earth, except that the recent warming is caused by “well-established, long-term, natural climate trends” and the world will cool in the future because of the sun.


  34. 184
    VagabondAstronomer says:

    Cite sources please. Also include other MS globally.

  35. 185
    dhogaza says:

    Bingo! (Actually, I doubt they use exactly the same raw data — no doubt there are some differences — but the overlap is obviously going to be huge)

    The information I’ve read is that the GHCN database includes all the available data that’s not restricted by distribution agreements. This is what GISTEMP uses, and represents about 95% of the data used by CRU, the other 5% being the data subject to such agreement and which McIntyre et al have been screaming about being “hidden” for all of these years.

    Is the publicly available data all at one site, or at various sites?

    As you’ve probably gathered from my post, one site, along with a whole lot more.

    As you can see, the data’s been very effectively kept secret and hidden from view on a public US government website.

    It’s a wonder that the denialists haven’t been telling this to people with the same vehemence they’ve screamed “hidden data! hidden data!”, isn’t it?

  36. 186
    dhogaza says:

    Oh, Jonesy, and as far as that other 5% that’s restricted and used when creating HadCRUT (but not NASA GISTEMP), the data can be had from the individual countries, though unfortunately often for a fee.

    See, McIntyre et al have been asking for restricted access data for free that in some cases CRU had paid for, rather than going to the source and paying for it themselves. Understandable, who wants to pay for data? And not all of the restricted data has been paid for, but still – you do get the point, I hope? Asking people to give you something they don’t have the right to give you is just fine. When rejected, screaming “fraud!” “misconduct!” and the like is not.

  37. 187
    John MacQueen says:

    “The implication is that something secretive and possibly nefarious has been afoot in the way data have been handled, and that the validity of key data products (especially those produced by CRU) is suspect on these grounds.”

    Not so at all.

    The implication that there could be honest mistakes made with no nefarious intent is also there, which would render the products suspect on those grounds as well.

    [Response: Except that this would be even more unlikely, since the mistakes mistakes made by CRU would have to be nearly identical to the mistakes made by NOAA, GISS, and the Japanese compilation, since all the data sets agree very very well with one another. That's even more impossible to believe than a conspiracy!--eric]

  38. 188
    Steve Fish says:

    Comment by CM — 16 December 2009 @ 2:07 PM:

    Eric chose data on the basis of the length and completeness of data sequences. One might complain that his specific choice had a bias. Splitting the data into two sets is a further test of random selection. A problem would be indicated by a difference between the two sets. This is a common strategy. Think of it as similar to splitting a card deck for shuffling.


  39. 189
    Norman says:

    #112 Kevin McKinney says:
    16 December 2009 at 9:07 AM

    “And Arctic amplification of warming has been observed in spades. However, it’s least marked in winter, since there is virtually no insolation at the highest latitudes during that season.

    No insolation=no greenhouse effect.”

    My understanding of the “greenhouse effect” was that it was not determined by solar radiation but would be more pronounced in the Arctic region. Using the Stephan-Boltzmann Constant, even a cold arctic surface will still emit IR (cold maybe by our standards but still very warm compared to absolute zero). The carbon dioxide in the Arctic atmosphere will absorb this radiation, warm, and in turn emit some radiation back to earth to replace some of the energy it lost.

  40. 190
    Norman says:

    #161 rb says:
    16 December 2009 at 3:37 PM
    In response to #92, how long have you been collecting data?

    Thanks for you response and information. I am only starting to look at northern data the last month or so to get a “feel” for the Northern climate. Your data set does indicate the region has experienced warming. My question was what was causing the current cooling I have been observing.

    I am ignorant of the climate forces working up there. If greenhouse theory makes sense for you data set but I was wondering why it looks like it is cooling. I may be using too small of a data set.

  41. 191
    Norman says:

    #158 Rando says:
    16 December 2009 at 2:50 PM
    92 and 116: Take a look at today’s temps in Alert (-7C) and Eureka (-11C) in Nunavut, way up north in northern Canada. They’re forecasting +5 and rain in Iqaluit on Friday – that’s on Baffin Island. The Arctic sea ice is going to start melting if that keeps up. Mind you, it’s -31C over here in Yellowknife today, so you could just say….interesting weather we’re having today, isn’t it?

    Do you have any theories as to what is going on to cause this effect. Very cold or normal for Yellowknife but much warmer in very North Canada. Is some warm ocean current causing this?

  42. 192
    Steve Fish says:

    Comment by lgp — 16 December 2009 @ 1:24 PM:

    You are incorrect regarding peer review. Reviewers look to see if the study authors used the appropriate data and analysis to support their findings. It is more complicated, but these are the basics.

    The point of the original post was to demonstrate what critics, such as YOU, can do to test the veracity of the research. If you don’t trust the findings of climate researchers, all your unsubstantiated complaints mean zilch when you can test them yourself to demonstrate your point. Get busy.


    [My emphasis. --eric]

  43. 193
    Ron R. says:

    John P. Reisman, while I did look at your first link before I finally got the time to look over your arctic and glacier pics. So far they are the best I’ve seen. I especially like the glacier page. That’s pretty much what I’m talking about. Good job. Now if we can do that for the other effects as well we’ll have something!

    For some reason there is a large blank space on your pages before the info begins. Also when I clicked on some of them on the arctic page a page came up that said “502 bad gateway”.

    On the northwest passage here’s ESA’s 2007 view.

  44. 194
    Cardin Drake says:

    This is an interesting post and cuts to the heart of the matter. I think at this point in order to regain credibility, CRU will have to demonstrate exactly what you are trying to prove–that the adjustments to the raw data make sense and will withstand scrutiny. I have not seen anybody who has taken issue with this analysis on any of the skeptical blogs yet.
    However, they have pointed out that there is a significant difference between the raw and adjusted numbers on NOAA’s published USHCN data. Currently it is about .5 F, which is large portion of the 1.3 degree anomaly.
    That is hard to reconcile with the CRU data since you would expect the adjustments to be similar.

    [Response: I'm not "trying to prove" anything. I'm showing people how to take a look at the data for themselves and make an assessment about whether CRU is full of cheaters or the deniers are full of it. And CRU doesn't need to do anything, since any fool can do the analysis we did. There's a simple reason none of the skeptical blogs have taken issue with what we did: they know we're right. Indeed, the fact they are ignoring it tells you something, doesn't it? I thought this post would actually be the end of the discussion, but evidently, I was naive.--eric]

  45. 195
    Terry says:

    I seem to remember sometime ago Gavin implying that one should only need about 100 high quality temperature stations to adequately characterise the global temperature. Why then dont they take that advice and simply ditch the contaminated sites, and use only pristine sites. I would expect that there are at least that number on the globe. The whole issue of adjustment and homogenization errors surely then disappears.

  46. 196
    John says:

    Has anyone written a rebuttal of the following document by Christopher Monckton?

    I’m particularly interested in any answers to the supposed “endpoint fallacy” since it seems rather absurd but I can’t put my finger on why.

    Thanks in advance.

  47. 197
    ZT says:

    Thanks for the link Kasphar – I’ll have a look.

    Any chance for an answer on Tom Wigley’s question about the possible divergence of land and sea temperatures?

    On the original analysis – an interesting statistical test might be to examine the similarity of the two sets of stations before and after processing.

    This would indicate whether value adding could have the effect of increasing, decreasing, or keeping constant the statistical properties of the two sets of data. The hypothesis being that referencing various stations in the homogenization yields to correlation across the data.

    This would might help to strengthen the argument. Currently a skeptic might claim that the homogenization processing introduces a common bias into all series.

    Are the original data available for these particular stations?

  48. 198
    kdk33 says:

    Surface station reconstructions are suspect. Period. Too many stations, too many corrections, too many data splices, too many complicated averages, too many people outsmarting themselves – the noise is bigger than the signal.

    Stick to the satellite data. It’s been warming some. Big deal.

    But why? – that’s the question.

  49. 199
    Ian says:

    I don’t think this is inappropriate given the title of this thread. but Do you have any comment on the allegations from Russia that CRU are very selective in their choice of weather stations in Russia?

    [Response: Since the only substantial differences appear to be in the 19th Century, the issue is very likely to be connected to instrument changes/metadata changes that the IEA analysis doesn't look at at all. This is just bandwagoning and the flinging around of baseless accusations by a right-wing think tank. - gavin]

  50. 200
    Joseph Sobry says:

    155 Cattle, meat etc.
    Please see
    The world cattle population is estimated to be about 1.3 billion head.[1]. India is the nation with the largest number of cattle, about 281,700,000 or 28.29% of the world cattle population, followed by Brazil: 187,087,000, 18.79%; China: 139,721,000, 14.03%; the United States: 96,669,000, 9.71%; EU-27: at 87,650,000, 8.80%; Argentina: 51,062,000, 5.13%; Australia: 29,202,000, 2.93%; South Africa: 14,187,000, 1.42%; Canada: 13,945,000, 1.40% and other countries: 49,756,000 5.00%.[51] Africa has about 20,000,000 head of cattle, many of which are raised in traditional ways and serve partly as tokens of their owner’s wealth.

    Please remember that cows in India are scared, sorry, I mean sacred.
    Cattle in India not only eat grass and other plant matter but serve other environmental needs I will not describe here. I do not know but I think that cows are not eaten by humans in India. One wonders what happens to them after uselessly pumping CO2 and methane in the air for a lifetime.
    Also the Masai herders in Africa are very attached to their cattle.
    There are probably other people on the planet with similar penchants.

    The number of Bison in the USA was estimated at ~60,000,000 when brave hunters shot practically all of them in a geologically (catastrophically for the bison) very short time mostly from the safety of trains. It would be interesting to see if there was a drop in methane or CO2 levels in the Greenland Ice Record once this valiant task was completed.

    While it is rightly recommended not to eat too much beef or any other meat for rational dietary and health reasons that is no reason to end all production of meat which is a very valuable source of food for most humans. Indeed there are a lot of humans who would fare much better if there was some meat in their diet.

    A more reasonable (much smaller) amount of meat in northern hemisphere human diets is certainly recommended and would put a lower ceiling on the number of cattle and other animals raised for food not to mention the amount of adipose tissue in the general population in said hemisphere.

    In addition one should be careful what one wishes. Grazing animals and grasslands live in a close symbiosis. It would not surprise me to learn that uncropped grasslands produce more methane and CO2 than the symbiotic grass and grazers.

    One would also think that cattle and other grazing animals were and are part of the normal carbon cycle.
    With the exception of some aspects of feedlot practices for poultry and pigs and for cattle (usually inflicted towards the end of an animal’s life) the conversion of plants into animal tissue and activity is perfectly natural . That is what we humans as mammals and omnivores do directly by eating greenery or indirectly by eating meat.

    Furthermore the total conversion to a plant food diet for the human species may cost more in CO2 and methane than an appropriate amount of meat eggs dairy and other animal products in the diet.It is my understanding that fleets of refrigerated trains trucks and airplanes are currently used to supply fresh lettuce, fruits and other plant food to the millions in the cities all over North America. This is done especially during the winter when no local produce is available. I can scarcely believe that his is not also the case in Europe and other parts of the world. I am trying to grasp how much more transport will be needed to supply all of humanity with a plant food only diet.
    It would be much better if the people would eat the locally produced animal products during the winter/spring and the locally produced fresh plants during the summer/fall. After all that was the old practice just a few decades ago and going back many hundreds of years.

    I honestly think we should keep focused on fossil fuels or fossil carbon.
    The consumption of fossil fuels does a lot more damage to our health, our environment and our planet than any CO2 or methane exhaled in any manner or direction by any mammal or other animal for that matter.

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