RealClimate logo


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 (http://dss.ucar.edu/datasets/ds570) 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 http://www.cru.uea.ac.uk/cru/data/temperature. 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).
CRUobject
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 (http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter3.pdf), 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.


References
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. 51
    Theo Hopkins says:

    There was a link earlier to the Washington Times.

    Oppps.

    Being a Brit I, at first, mistook this for the Washington Post.

    Is this intended?

  2. 52
    t_p_hamilton says:

    DB has learned that there are other greenhouse gases, and has learned that the globe has warmed over the past century, 0.5 degrees total, askin what is the big deal?. Next up: learning that the rate of CO2 warming has accelerated since 1970 to 1.7 degrees for the next century unless something is done. Learning that even if CO2 were to stop being emitted tomorrow, the temperature will continue to rise because energy absorbed > energy emitted.

    The following paper on forcings of various atmospheric components has a familiar name (if too technical, read the news blurb in the same journal)

    Shindell, D.T., G. Faluvegi, D.M. Koch, G.A. Schmidt, N. Unger, and S.E. Bauer (2009) Improved Attribution of Climate Forcing to Emissions. Science 326, 716 – 718 doi: 10.1126/science.1174760

  3. 53
    t_p_hamilton says:

    ZZT asks:”Question – how do we know that these stations are not simply measuring the growing proximity of asphalt and air conditioning units with time?”

    Are the asphalt and AC units sneaking up slowly on the thermometers?

  4. 54
    Tom Fuller says:

    If you would like to comment on the article I wrote, you may find it here: http://www.examiner.com/examiner/x-9111-SF-Environmental-Policy-Examiner~y2009m12d15-Global-warming-by-the-numbers

    Thank you for your response and the useful information.

  5. 55
    dhogaza says:

    There was a link earlier to the Washington Times.

    Oppps.

    Being a Brit I, at first, mistook this for the Washington Post.

    Is this intended?

    While I can’t speak to intention, I’ll point out that the Post drifts closer and closer to the Times with each passing week … it is no longer the paper you probably grew up thinking it was.

  6. 56
  7. 57

    #31 Paul Klemencic

    The problem with the McKitrick tax is that it puts the solution behind the initiation of the problem. Sort of like trying to stop a forest fire after the trees have all burned down. It makes no sense of course, but that’s McKitrick’s brain in action.

  8. 58
    Feli says:

    ZZT asked
    Question – how do we know that these stations are not simply measuring the growing proximity of asphalt and air conditioning units with time?

    Like this station perhaps?
    http://www.zamg.ac.at/histalp/images/stationmode/T01_SON_year.png
    http://www.helios.at/cfm/galerie/index_detail.cfm?galerie_id=218 (no need for air condition there)

    The National Weather Services have a lot more station data then those integrated in the worldwide grids and they have scientists analysing these data. I guess they would realise, if most of their own stations show cooling while the GISS (or CRU) data in the region show warming.

  9. 59
    David B. Benson says:

    Barton Paul Levenson (50) — Great!

    For the purist, maybe alos add a version using an ARMA(1,1) version to handle the autocorrelation; I’d certainly find that of interest!

  10. 60
    DB says:

    RE: Post 52 by t_p_hamilton:

    Wow, one day it is 6°, the next day it is 3° , and today by your estimation the warming will be around 1.7° over the next century? Does this include the .5° already arrived at, which by the way, only half is due to C02, and probably less if you figure in solar activity? Does your 1.7° degree figure include variables such as solar cycle 25, which by all estimations is forecast to be the weakest in many years? I agree that 1.7° is probably a fairer number than 6 degrees. However one can’t help but remember when Michael Crichton was lambasted for his book, that has oddly turned out to be prescient. I include the post on ‘State of Confusion’ that was posted on Real Climate by Gavin on 13 December 2004.. Makes you wonder why the book was attacked so vigorously here on Real Climate.. But I digress. In any event, here is the link to the post in the archives here on Real Climate, and both the posts and comments are well worth a read.

  11. 61
  12. 62
    dhogaza says:

    The problem with the McKitrick tax is that it puts the solution behind the initiation of the problem. Sort of like trying to stop a forest fire after the trees have all burned down. It makes no sense of course, but that’s McKitrick’s brain in action.

    It’s just another dodgy attempt to forestall meaningful action for another couple of decades.

  13. 63
    Joe Enscore says:

    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.

  14. 64
    Jim Bouldin says:

    Now that’s my kind of analysis! Thanks.

    we extracted a sample of raw land-surface station data and corresponding CRU data
    Meaning, the CRU grid cells were spatially co-located with the stations?

    I don’t see much difference in variance between station and CRU data, but a big difference in kurtosis. Any ideas as to why?

  15. 65
    David B. Benson says:

    DB (61) — It is rather that all the othr forcings, both up and down, approximately cancel out over long enough time, leaving but ln(CO2):
    http://bartonpaullevenson.com/Correlation.html
    Under the assumption that everything cancels out, the Arhennius formula gives an “immediate” warming of close to 2 K for 2xCO2; this generally agrees with an eventual warming (equilbibrium climate sensitivity or ECS) of about 3 K, which is IPCC AR4′s “most likely” value for ECS.

  16. 66
    richard says:

    Curious as to the reaction to the DOE “Litigation Hold Notice,” sent to all DOE employees. This notice demands that no climate science and or CRU related data including personal recordings, notes, emails, phone records etc. be deleted or destroyed.

    Is DOE planning to sue anyone involved with CRU?? And do they have jurisdiction?? Quite dodgy it seems.

  17. 67
    Charles Copeland says:

    JSC (#30) writes:

    I am concerned “researcher bias” is starting to be a major factor on this website and on “skeptic” websites as well. So much of the analysis seems to be an “us vs them” affair that is is hard for me to avoid thinking about researcher bias.

    My only cavil with this statement is the use of the present tense (“is starting to be a major factor…”). I would say that publication bias has LONG been a major problem. The fact that the term itself goes virtually unmentioned at RealClimate is itself of its pervasiveness, in that nobody here seems to have reflected very much on the issue (only two hits at RC, one in 2005 and one in 2007).

    I know that Patrick Michaels is a persona non grata here but whatever about his shortcomings I think his chapter on the subject in his recent book ‘Climate of Extremes’ is a must-read for RC’s editors. It’s Chapter 7 ‘Pervasive Bias and Climate Extremism’ and it includes one core argument that I at least consider (at this writing anyhow) irrefutable. It’s that in the absence of bias “each new research finding stands an equal probability of making the predicted effects of global warming on “environmental and health damages” “better” or “more severe”.

    But this does not appear to be the case, as Michaels demonstrates by classifying articles on climate change published in ‘Science’ and ‘Nature’ as indicating the impact of global warming to be ‘better’, ‘neutral’ or ‘worse’. The ratio better to worse is approx. 8:1, which suggests that climate scientists have been appallingly optimistic in the recent past (a slur which they do not accept) or that there is a tendency to ignore optimistic or neutral outcomes today: after all the null hypothesis is no news, and the positive outcome is even less news than the null hypothesis. Besides, the null hypothesis and null funding tend to go hand in hand.

    Instead of shooting from the hip, I would suggest that commenters take the trouble of reading the chapter in full — it really is worth the effort and my summary is far too brief. Indeed I would suggest that RealClimate (to demonstrate their scientific integrity and enhance their credibility) orchestrate a wide-ranging and no-holds-barred debate on the issue.

    [Response: This argument is simply nonsense. It implies that we knew exactly the severity of the climate change problem years ago and all subsequent work is just details. In fact, it is much more likely that the we underplayed the severity of the problem, and are now coming to realise all the issues. No ‘even balance’ between ‘better’ or ‘worse’ would be expected. Instead, the balance determines the direction of increasing or decreasing concern. – gavin]

  18. 68
    cougar_w says:

    #30

    You don’t much understand the scientific method.

    There is no “them”, but only “us”

    It is not opinions, it is observations.

    cougar

  19. 69
    Doug Bostrom says:

    Notice how all progress at Copenhagen has (not) been brought to a halt via the release of the CRU information.

    http://www.nytimes.com/2009/12/16/science/earth/16forest.html?hp

    Hah-hah! Somebody somewhere is not very happy right now. They thought they had carborundum, instead it turns out they stole jello powder. Poured into the gears, vanishes without a trace, without even a last hurrah.

    Sorry, contrarians, the juggernaut of improvement has plenty of momentum now, more than you can ever hope to arrest.

    It’s pretty telling that whatever party staged the CRU stunt was so tightly wound up into their own strange perspective, they actually thought a few emails were going to bring the house down.

    Perhaps if less time were spent skulking, muttering about conspiracy theories and going though other people’s garbage, the motley crew of freaks behind the CRU theft could concentrate on attempting to construct a coherent and robust hypothesis that integrates and explains away all or at least most of the many indications we’ve seeing that our planet is a little too small to suffer arbitrarily large, random adjustments and still emerge with an unscathed film of air, water and regolith.

  20. 70
    cougar_w says:

    #49 “how do we know…”

    That is an excellent question!

    To put it another way: How do we know that this planet is not simply measuring the growing proximity of asphalt and air conditioning planets with time?

    Huh? What about that? Smart guys.

    [sorry, couldn't help it]

    cougar

  21. 71
    t_p_hamilton says:

    DB has a fair question: Why did I say 1.7 degrees for recent trend?

    From wikipedia http://en.wikipedia.org/wiki/File:Satellite_Temperatures.png, “Each record is plotted as the monthly average and straight lines are fit through each data set from January 1982 to December 2009. The slope of these lines are 0.187°C/decade, 0.163°C/decade, and 0.239°C/decade for the surface, UAH, and RSS respectively.”

    DB also correctly states that figures such as 2-6 degrees are given for the NEXT century (assuming different emission scenarios, feedback, sensitivities, etc). The two degrees on the lower end of the scale are not too inconsistent with that, and is the lowest we can expect if we do nothing.

    The University of Wisconsin has an applet to play with. I put in freezing CO2 emissions at the current rate, temperature went up 0.7 degrees but had turned down by 2060. Making CO2 go to zero immediately, the temperature turns down immediately! This applet assumes a middle of the road climate sensitivity of 3 degrees for doubling CO2.
    http://carboncycle.aos.wisc.edu/index.php?page=carbon-budget-tool

  22. 72
    cougar_w says:

    SF Examiner is a waste of pulp. I’ve read stuff on the editorial page that would gag a maggot. Just went over there and read Tom Fuller’s piece; condescending rubbish.

    What makes me flip is these armchair upper crust toadies weighing in on science research like it were a horse race; the equivalent of “Well see here, I collect stamps from around the world which is a very exacting science and this is what I think about climate change…” just sounds silly after a while.

    Leave the science to people who know what the scientific method is, at least.

    cougar

  23. 73
    Jay K. says:

    DB is attempting the same end-around that has been attempted by so many for so long, that is implying that past rates of increase are typical and recent ones are not, therefore warming is….well, something.

    But a single answer to your questions, DB, would come in the form of: “Do you understand the positive feedback systems that have/will/are kicking into gear and that have the potential to cause massive warming?” You seem to be ignoring those and going for some low hanging fruit that has little to do with what is being discussed.

    The general consensus of warming since 1850 seems to be in the range of .48 deg C to .7 deg C. Eric has shown, here, that the CRU datasets, unadjusted, show .54 deg C, and has also said that the CRU data is typically lower than other datasets. So your concern appears more in the realm of concern trolling than actual intellectual rigorous questioning.

  24. 74
    jonesy says:

    Do the GISS and NCDC temperature charts (from 1880 on) use the same station raw data as CRU, or do they use different stations?

  25. 75
    lgp says:

    The article states “we extracted a sample of raw land-surface station data and corresponding CRU data.”

    Is the raw raw, or has it been “adjusted” prior to comparision to CRU using “concensus” approaches to UHI and other techniques to decrease older raw temperatures? If so it’s not RAW data. Showing that one can introduce the same type of biases into the raw data prior to comparision to CRU only shows that this analysis is not independent of CRU.

    [Response: Try reading the post again, slowly. What we did is what we said we did, plain and simple. If you want more details, go to the links we provided, which, yes, are the raw data. You are really trying hard to find fault where there isn’t any.–eric]

  26. 76
    Ron R. says:

    Guys, all this argument about datasets and math, station location and the causes of climate change (and ALL the acronyms that people seem to love) never ever seem to end. They just go on and on and…

    And that’s fine, that’s science, we need that but it’s all Greek to the average Joe/Jane and gives the impression that nothing is really known for sure. After all these guys are still arguing about it!

    If I may, we could use a page or another site containing the actual-concrete-visual-evidence of climate change. A visual page, like before and after photos of deglaciation, tundra thawing, the loss of ice in the arctic (and the opening up of the northwest passage) and calving in the antarctic. Maps showing the change in range and migration of species from the native habitats. Rising sea levels (Tuvalu for example). Graphs of the earlier arrival of spring. Graphs of the rise in CO2. Lots of before and after stuff. You know what they say about a picture being worth a thousand words, and that the camera doesn’t lie.

    Maybe this could be a page that people can contribute to on a regular basis, kind of like the recent Data Sources page.

    People also need to understand that perhaps 95% of the basis for Climate Change is known, and perhaps 4% unknown. Then there is the 1% which we don’t know that we don’t know bit (the random factor in every situation).

    Right now when one clicks on a link on a subject to the right he comes up with a list of previous posts that mention the subject somewhere therein which is not really that helpful if one is looking for encyclopedic info on the topic.

    Just a thought.

  27. 77

    #76 Ron R.

    I started collecting images here

    http://ossfoundation.us/projects/environment/global-warming/myths/images

    sections like

    http://ossfoundation.us/projects/environment/global-warming/myths/images/glacier-retreat

    and

    http://ossfoundation.us/projects/environment/global-warming/myths/images/arctic

    I think are helpful. i will try to concentrate more on this. If you, or anyone has image suggestions let me know and I will look at adding or making new sections

    http://ossfoundation.us/contact-info

  28. 78

    Dear Ron R. :

    You have an excellent point. For those of us who glaze over at tables and graphs, Gavin Schmidt has co-authored an excellent book of images and photographs that show the reality of climate change.

    http://www.realclimate.org/index.php/archives/2008/01/our-books/#Schmidt09

    http://www.realclimate.org/index.php/archives/2008/01/our-books/

    seeing is beleiving.

    yours
    Frank Johnston

  29. 79

    Sorry this is a bit OT:

    John Stewart’s Daily Show tackles the “debate”. Very funny as usual.

    http://www.thedailyshow.com/full-episodes/257989/mon-december-14-2009-sigourney-weaver

  30. 80
    Doug Bostrom says:

    “It’s Chapter 7 ‘Pervasive Bias and Climate Extremism’ and it includes one core argument that I at least consider (at this writing anyhow) irrefutable. It’s that in the absence of bias “each new research finding stands an equal probability of making the predicted effects of global warming on “environmental and health damages” “better” or “more severe”.

    Here’s an experimental analogy you probably should not attempt.

    Select 10 of your favorite, flammable objects. Your house, your car, your piano, your television set, your sofa, et al; find a good variety of things that are made differently and to various purposes yet all have in common that they burn fairly readily once ignited.

    Now, one by one, set each object ablaze. Observe carefully, record the results.

    How many samples out of 10 extinguish themselves?

    If you then publish results showing that your samples of possessions each burned fairly thoroughly, to the point of destruction, does that mean you’re “pro-fire”, biased?

    Or, pick the same samples, smash each with a hammer, wait to see which ones reassemble themselves. Once you’ve become bored, ask yourself: Are you pro-entropy?

    What an absolutely idiotic argument for Michaels to make.

  31. 81
    Steve Bloom says:

    NASA put together a special page of visualization links for the Copenhagen conference. It could stand to be more user-friendly, but there’s an awful lot of good material.

  32. 82
    Ray Ladbury says:

    Fine guys, let’s talk about Darwin:

    http://scienceblogs.com/deltoid/2009/12/willis_eschenbach_caught_lying.php

    Now go wash the egg off your face and we can get back to science.

  33. 83
    Edward Greisch says:

    I wouldn’t want to advocate anybody doing anything wrong or criminal, but I am so tired of hearing about the denialist hack……. I’d bet [no not really wager] that if somebody in some country that doesn’t have internet laws cracked into the emails of the denialists, some really juicy stuff would be found. Perhaps the British Attorney General can subpoena emails? How is the criminal investigation going? Will the court record be published?

  34. 84
    Dan e Bloom says:

    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….

  35. 85
    jonesy says:

    I have a very challenging question. Who is Eric? The name is not on the contributor page.

    [Response: Second page. – gavin]

  36. 86
    J. Bob says:

    Enclosed are few illustrations of long term temperature anomaly averages. This was done to compare how temperature data results can change as more start ions started to record temperature. It also starts to give some perspective of comparing early temperatures with current ones. The secondary purpose was to have a set of long term temperatures to compare against sunspot and proxy data.

    The 1st compares the E. England data from 1659 to 2008 with the Hadcet data from 1850 to 2008. In the case the E. England data was “anomalized” to be compatible with the Hadcet data. The “anomalization consisted of computing the average from the time period of 1961 to 1990. This average was then subtracted from the data set’s raw data to arrive at the “anomaly”.
    http://www.imagenerd.com/uploads/lt-temp-1650-2008-1-Rxrdy.gif
    The upper figure is the raw data, while the lower figure shows the result of a 40 year Fourier filter. Note the downturn of the English data and the apparent flattening of the Hadcet data. Also the slope of the 350+ data appears to be flatter the 150+ year of the Hadcet.

    However this is only one station, so let’s take a look at stations with records starting before 1750. The figure below show the “anomalized” data from 4 early groups: E. England, DeBilt (Netherlands), Uppsalla and Berlin ( the last two courtesy of http://www.rimfrost.no/ ), compared to the Hadcet. In this case each station was “anomalized” first and then the average was computed (ignoring missing data, not the best way to merge data, but a start)
    http://www.imagenerd.com/uploads/lt-temp-1750-2008-4-EyvXd.gif
    Again the longer term data shows a flatter trend line then the Hadset. The higher end on the Ave4 data is a little skewed at the end due to the Uppsalla data being about 1 degree higher then the Debilt, and Berlin data, and ~1.5 above the English data. Also it shows a gradual rise in temperature up to about 1965 when it seems to rise rapidly. The question is why? With all the industrialization prior to that time, why the sudden upswing on that data set?

    The next figure is a repeat of the above, only using data from stations which started recording temperature prior to 1800 (as gathered from Rimfrost plus the English and DeBilt data). This included Paris, Geneva, Edinburgh, Prague, etc.
    http://www.imagenerd.com/uploads/lt-temp-1800-2008-14-9ZSv8.gif
    With this data set, the rapid rise of temperature begins about 1850 and is greater then the Hadcet.

    The next set is the “anomalized” data from stations which started recording prior to 1850 ( including St. Paul Mn (Fort Snelling) and NYC).
    http://www.imagenerd.com/uploads/lt-temp-1850-2008-27a-UtBGD.gif
    Here the rise after ~1870 is not so dramatic, but it does show a sudden rise after the late 1800’s. Another thing is that the later date record include a note that some of the later data has the note GISS attached to it, so it may not be clear when the original raw data begin and the GISS adjustments were made.

    The last figure is a average of 50 stations with recording lengths beginning prior to 1900. These include New Zealand, Siberia, Beijing, Malta, Shanghai, Australia, St. Helena, etc.
    http://www.imagenerd.com/uploads/lt-temp-1900-2008-50a-PhLn0.gif
    At this point it can bee seen that smoothed lines of the Ave50 and Hadcet start to resemble one another a bit closer. The 40 year MOV was also included to compare it and the 40 year Fourier filter. It shows the Fourier goes out to the ends of the data, instead of being “cut off”.

    So in summary one could make the case that there seems to be a slowing down of the temperature after some decades of rising, for whatever reason. The other is that in spite of the ups and downs of temperature oscillations the long term rise (from mid 1700’s) is not as bad as looking as the last ~150 years.

    Time to call it a night. Temperature now –5 F., tomorrow will be a good day for some skiing.

  37. 87
    ZT says:

    Many thanks for the links on asphalt not producing warming. I am surprised to read that the heat capturing effects of asphalt are so easily dismissed as myth – there must be some effect – as anyone who walks across a parking lot in the summer would attest. But perhaps this is indeed vanishingly small. However, I think that the records do show that stations which are not moved and are not in developed areas (and therefore do not have an increase of asphalt around them per unit time) show a lower warming rate. Has anyone investigated this – or do the statistics not permit a conclusion on such small data sets?

  38. 88
    Steve Fish says:

    Comment by Charles Copeland — 15 December 2009 @ 6:30 PM:

    You say– “..in the absence of bias “each new research finding stands an equal probability of making the predicted effects of global warming on “environmental and health damages” “better” or “more severe”.

    In addition to what Gavin and Doug Bostrom have said:

    1. The published research by climate scientists is not involved in predicting the effects of warming; instead they estimate the amount of the change or, for example, the amount of ice melting. This is not a subtle difference from “environmental and health damages.”

    2. In areas of research in which the experimental and null hypotheses are found with equal frequency are those in which the effect being studied is very weak or non existent so (usually in studies with a large n) random effects throw the results one way or the other. An example of this is the research concerned with the relationship between cell phone usage and cancer where there are quite a few studies finding small positive or negative relationships. An example of a limiting case might be a dozen studies of the relationship between drunk driving and automobile accidents. Do you expect that the null and experimental hypotheses would have equal probability?

    3. Finally, especially in a relatively mature field, most studies research some component of a subspecialty within the area. In the climate sciences, for example, there might be a study of a new tree species that might be useful for a long term temperature proxy, or a new method for reconciling spatial and methodological discontinuities between temperature monitoring stations may be tested, or a new way of measuring back radiation of different infra red radiation frequencies could be explored in order to identify the differential effects of the different green house gasses.

    For short, given that you have represented Patrick Michaels accurately, he doesn’t know what he is talking about. This concept is very simple, but if you wish me to read the chapter you will have to send it to me because I am not buying it.

    Steve

  39. 89
    Ian George says:

    Checking raw data against trend maps, I came across the following.
    Using the the av max temp raw data for Lismore, NSW, Australia, I found there had been changes when the data was used to create the official long-term temp and anomaly maps. The early raw data records appear to be ‘dumbed down’ as follows.
    Temperatures prior to 1940 show a discrepancy of between 0.4c to 1.0C.
    Temperatures from 1940 – 1979 show a discrepancy of about 0.3C.
    Temperatures from 1980 are consistent with the raw data.
    Thus when the max temperature and the anomaly graphs are produced they both show a continuous warming from 1910. When the raw data is plotted, there is no warming apparent. Some examples are:-
    1919 – raw data av was 27.4C Dropped to 26.7C for official graphs.
    1940 – raw data av was 26.4C Dropped to 26.1C for official graphs.
    1980 – raw data av was 26.1C No change at 26.1C for official graphs.
    2002 – raw data av was 26.5C No change at 26.5C for official graphs.

    Also the mean temps for this station at NASA gistemp show the same pattern. After the raw mean temps are ‘homogeneity adjusted’, the early entries are adjusted down 0.5C and the later entries are hardly adjusted at all. This results in a warming trend in temps which would not be there before the adjustment.

    After the famous ‘blink’ map, it makes it hard for an innocent bystander like myself to believe the warming is as bad as you say it is. And now with the emails and the programming notes, it makes it harder to believe as it confirms what I have been looking at.
    It’s not what you, the western public, our governments, etc think of these emails, etc. It’s what China, India et al make of it all.

    [Response: What on earth are you talking about? The raw data are what we plotted in this post! Don’t rely on other people’s plots though — do the exercise we did and look at the original data. It is not that hard.–eric]

  40. 90
    Ron R. says:

    John P. Reisman, Frank Johnston (et al :-)) it’s not my site nor my call. It’s just a suggestion.

    Currently if I want to find visuals on these things I have to hunt all over the net. Maybe there’s a site that I am not aware of with the visuals. On thinner ice is one. I think the European Space Agency has a shot of the northwest passage. I suspect that there is a lot out there and it sould be gathered.

    Just looked at jour site John. Nice start. A good first page to send newbies.

  41. 91
    David Wright says:

    An analysis here claims to show average adjustments as a function of time. If that plot is correct, you would expect no difference in adjusted and unadjusted trends for the period 1850-now, because the adjustments are negligible at both ends of that time period.

    However, because of the significant downward adjustment near 1900, you would expect a significant difference in adjusted and unadjusted trends for the period 1900-now. You would expect the adjustment to increase the trend by about 0.25C/c, about a 50% difference.

    You would also expect a significant difference for the last ~30 years, because there appear to be about 0.1C downward ajdustment of temperatures in the 1970s relative to the present. Thus a large part of increase in the “recent” trend above the long-term 0.5C/c trend would be attributable to adjustments.

    Of course, that doesn’t mean the adjustments are wrong. It just means they are relevant. Do you claim that the cited adjustment plot is wrong, i.e. you would also find no significant difference between adjusted and unadjusted trends for the periods 1900-now and 1975-now? Or do you acknowledge that the adjustments are important for those periods, and simply claim they are trustworthy?

  42. 92
    Norman says:

    Because of the Internet, I am able to look at temperatures around the world in an recording station. I have been checking out towns like Fairbanks Alaska, Yellowknife Canada, and Yakutsk Russia as samples.

    The AGW theory claims that the Arctic region will experience the greatest degree of warming first.

    So far these locations have been average temperatures or below. A few days they are slightly above. My question is why? What is causing the cooler temperatures in the Arctic regions this season. I understand there can be temporal fluctuations, I just don’t understand using AGW theory why these places are now cooler than previous recordings. What climate forces are cooling the North this winter?

  43. 93
    tharanga says:

    Re 89:

    This sort of thing (picking some random station, not understanding why certain adjustments were made, and then wildly extrapolating to the entire data set) seems to be the flavour of the moment.

    Giorgio’s code produces a list of stations with the trend introduced by the GHCN homogenisation for each (which isn’t used by GISS, by the way, people).

    Pretty much for every station like Darwin there’s also a station where adjustments introduced a cooling trend. Perhaps I should start a blog, so I can hype up these cooling stations, pretend the homogenisation procedures aren’t published, and finally accuse people of the fraud of hiding the Incline?

    p.s. eric, you keep promising you’ll sign off. Feeling a bit addicted to the nonsense of the comments?

  44. 94
    Arie Brand says:

    Offtopic but worthwhile: Monbiot versus Plimer. The “Artful Dodger” exposed.See:http://www.abc.net.au/lateline/content/2009/s2772906.htm

  45. 95
    Doug Bostrom says:

    “It’s not what you, the western public, our governments, etc think of these emails, etc. It’s what China, India et al make of it all.”

    If one pokes one’s head out of the enormous polka-dotted ass of the contrarian pantomime horse, one can see that China et al are responding to climate change w/enormous financial, political and diplomatic capital investment, lending a priority to the issue that imposes real opportunity costs in other areas. In other words, conclusions have been drawn, minds are made up and courses of action set.

    The train has left the station; few of the people responsible for addressing this issue on the policy level give a rat’s ass about a rabble of cranks on the Internet left standing on the platform of history, yammering on and shadowboxing their war as witless conscripts of the pointy end of the spotty fake horse.

    All this desperate tilling and hoeing and sifting in search of supposed hidden footprints of conspiracy left in temperature records is:

    Choose any/all
    )Pathetic
    )Amusing
    )Pathological
    )Degenerate
    )Pointless

  46. 96
    caerbannog says:

    (#91)

    An analysis here claims to show average adjustments as a function of time. If that plot is correct, you would expect no difference in adjusted and unadjusted trends for the period 1850-now, because the adjustments are negligible at both ends of that time period.

    Is it reasonable to conclude from that plot that the differences between adjusted and unadjusted *temperatures* should be at a maximum during the 1900-1920 (eyeball approximation) period? If so, I see no evidence of that in RC’s raw vs. adjusted plots.

  47. 97
    Ian George says:

    From 89
    Response
    ‘What on earth are you talking about? The raw data are what we plotted in this post! Don’t rely on other people’s plots though — do the exercise we did and look at the original data. It is not that hard.’

    That’s what I’m talking about. The data received by NASA from Australia had already been ‘corrected’ and they have adjusted it again – down prior to 1980 for the Bureau in Australia and then again downward for earlier data by NASA.
    Later data reads as per the raw data. They’re the official figures I’ve quoted, nobody else’s.

  48. 98

    #90 Ron R.

    There is an image in the Arctic section of the Northwest passage

    http://ossfoundation.us/projects/environment/global-warming/myths/images/arctic/20080811_Figure4.jpg/view

    Though now it has been open three years in a row.

  49. 99
    Completely Fed Up says:

    And then Ian George would require the calibration tests of the thermometers. And the manufacturing report. And the history of the calibration team (they could be in on the conspiracy too!) and if any of that’s missing, well, obviously, this proves that the data is made up…

  50. 100
    Ian says:

    I had thought that since Climategate RC had become more inclusive but the response to post#5 shows all the old patronising and condescending attitudes that characterised RC. There are many scientists, of whom I am one, who know enough about climate change to know they don’t know enough. There are reports that suggest temperature data from Darwin is dodgy and it is a legitimate question to ask if it is true the temperature measurements in Antartica are from only one station . Most do not understand why the homegenisation of raw data almost always results in an increase rather than not. Addressing these questions without the arrogant overtones would be really appreciated by many

    [Response: How about dropping the endless repetition of non-facts? The adjustments are actually very close to Gaussian centered on zero in the GHCN procedure, and yet the blogosphere only ever focuses on the outliers on one certain direction. And no, the measurements from Antarctic (used by GISTEMP for instance) don’t just come from one station. Why do you automatically believe people who have been shown over and again to be misrepresenting the true situation? – gavin]


Switch to our mobile site