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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Climate Hustle

Are surface temperature records reliable?

What the science says...

Select a level... Basic Intermediate Advanced

The warming trend is the same in rural and urban areas, measured by thermometers and satellites, and by natural thermometers.

Climate Myth...

Temp record is unreliable

"We found [U.S. weather] stations located next to the exhaust fans of air conditioning units, surrounded by asphalt parking lots and roads, on blistering-hot rooftops, and near sidewalks and buildings that absorb and radiate heat. We found 68 stations located at wastewater treatment plants, where the process of waste digestion causes temperatures to be higher than in surrounding areas.

In fact, we found that 89 percent of the stations – nearly 9 of every 10 – fail to meet the National Weather Service’s own siting requirements that stations must be 30 meters (about 100 feet) or more away from an artificial heating or radiating/reflecting heat source." (Watts 2009)

Temperature data is essential for predicting the weather. So, the U.S. National Weather Service, and every other weather service around the world, wants temperatures to be measured as accurately as possible.

To understand climate change we also need to be sure we can trust historical measurements. A group called the International Surface Temperature Initiative is dedicated to making global land temperature data available in a transparent manner.

Surface temperature measurements are collected from about 30,000 stations around the world (Rennie et al. 2014). About 7000 of these have long, consistent monthly records (Fig. 1). As technology gets better, stations are updated with newer equipment. When equipment is updated or stations are moved, the new data is compared to the old record to be sure measurements are consistent over time.

 GHCN-M stations

Figure 1. Station locations with at least 1 month of data in the monthly Global Historical Climatology Network (GHCN-M). This set of 7280 stations are used in the global land surface databank. (Rennie et al. 2014)

In 2009 some people worried that weather stations placed in poor locations could make the temperature record unreliable. Scientists at the National Climatic Data Center took those critics seriously and did a careful study of the possible problem. Their article "On the reliability of the U.S. surface temperature record" (Menne et al. 2010) had a surprising conclusion. The temperatures from stations that critics claimed were "poorly sited" actually showed slightly cooler maximum daily temperatures compared to the average.  

In 2010 Dr. Richard Muller criticized the "hockey stick" graph and decided to do his own temperature analysis. He organized a group called Berkeley Earth to do an independent study of the temperature record. They specifically wanted  to answer the question is "the temperature rise on land improperly affected by the four key biases (station quality, homogenization, urban heat island, and station selection)?" Their conclusion was NO. None of those factors bias the temperature record. The Berkeley conclusions about the urban heat effect were nicely explained by Andy Skuce in an SkS post in 2011. Figure 2 shows that the U.S. network does not show differences between rural and urban sites.

rural-urban T

Figure 2. Comparison of spatially gridded minimum temperatures for U.S. Historical Climatology Network (USHCN) data adjusted for time-of-day (TOB) only, and selected for rural or urban neighborhoods after homogenization to remove biases. (Hausfather et al. 2013)

Temperatures measured on land are only one part of understanding the climate. We track many indicators of climate change to get the big picture. All indicators point to the same conclusion: the global temperature is increasing.

------

See also

Understanding adjustments to temperature dataZeke Hausfather

Explainer: How data adjustments affect global temperature recordsZeke Hausfather

Time-of-observation Bias, John Hartz

Berkeley Earth Surface Temperature Study: “The effect of urban heating on the global trends is nearly negligible,” Andy Skuce

 

 

Check original data

All the Berkeley Earth data and analyses are available online at http://berkeleyearth.org/data/.

Plot your own temperature trends with Kevin's calculator.

Or plot the differences with rural, urban, or selected regions with another calculator by Kevin

NASA GISS Surface Temperature Analysis (GISSTEMP) describes how NASA handles the urban heat effect and links to current data.

NOAA Global Historical Climate Network (GHCN) DailyGHCN-Daily contains records from over 100,000 stations in 180 countries and territories.

Last updated on 15 August 2017 by Sarah. View Archives

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Comments 401 to 450 out of 517:

  1. Eclectic @400, the change in radiation due to changes in the Earth's orbit (Milankovitch cycles) has mostly a regional effect, with almost no net effect on globally averaged radiative forcing.  The regional effect, however, can be quite large, and is sufficient to cause feedbacks which in turn are responsible for nearly 100% of the change in the energy balance between glacial and interglacial.  Those feedbacks can be changes in albedo (ice sheet, sea ice, and snow extent, along with changes to vegetation) and changes in greenhouse gas concentration (mostly CO2 and CH4).  According to a well known figure from Hansen, the greenhouse gases represent about 46% of the total effect, with the rest being from changes in albedo:

    (Source)

  2. Bulthompsn @399, I am not aware of anybody here "blowing off" human error when discussing Global Mean Surface Temperature (GMST).  Certainly the scientists who analyze it do not.  Indeed, the take great care to analyze potential sources of error, and to quantify the resulting uncertainty in their estimate of GMST, as shown in this graph from the Berkely Earth Surfact Temperature project (BEST):

    Note, that the grey shaded zone (the 95% confidence interval of the annual GMST estimate) shrinks rapidly from 1850 to 1880, and that post 1950 is very small relative to the decadal change in GMST.  Other teams do not typically show uncertainty on the graphs, but do publish the uncertainty with the data and in scientific papers discussing methodology.

    Nor are the satellite records more accurate than the surface records.  That is not just my opinion, but that of Carl Meares, head of the team that produces the RSS satellite temperature records, who said:

    "A similar, but stronger case [regarding trends] can be made using surface temperature datasets, which I consider to be more reliable than satellite datasets (they certainly agree with each other better than the various satellite datasets do!)."

    (My emphasis, source)

    This can be seen by comparing the size of the error in the trend estimate for RSS TLT vs HadCRUT4 for the period 1979-2012:

    Indeed, the satellite record requires more adjustments from a more disparate original data set than is required for the surface record.  This is something people pushing the accuracy of the satellite record never see fit to mention, but that it is the case is obvious when you have a look at (already partially adjusted) satellite data (top panel):

    For further information see here, here, here, and here (the start of a four part series).

    Finally, IMO, anybody who subscribes to a conspiracy theory of science ("This presumes that these current results are not being doctored") has thereby invalidated any claim they may have made to be informed, or rational on the topic. 

  3. Tom Curtis @401

    Thank you for the correction on CO2/albedo contributions to the episodic cooling process producing a (modern) glacial age.  The diagram you supplied indicates a (roughly) one-third contribution coming from CO2 changes alone, for the cooling phase.

    May I ask you whether the warming-phase figures are similar — or whether the CO2/albedo relationship is asymmetric regarding the actual causation of progressive warming as the planet exits a glacial age (i.e. whether CO2 plays a larger role in the ultimate root cause of the rapid 3-degree warming which terminates the typical glacial age) ?

    My error in #400, came from mis-remembering your recent statement [which I have checked as being: 11 January 2017, Comment #513, in "CO2 Lags Temperature"] that "90% of the temperature increase lags the CO2 increase".   Which (on reflection!!) certainly is not equivalent to saying that only 10% of glacial-to-interglacial warming is caused by the (Milankovitch) orbital variation and its arctic albedo effects .... with the rest being a direct consequence of CO2 and other GHG's. !

    I had concentrated more on the final question from Bulthompsn @399, where he had made an irritable (off-topic) question, which would have been better made separately on the "CO2 Lags Temperature" thread.   But since his @399 comments had a tone/manner suspiciously suggestive of a "drive-by" venting, I thought it pardonable to answer him entirely in this thread.

    If you can spare the time, Tom, please reply on the "CO2 Lags Temperature" thread.   I consider the "90%" figure a very useful one, in countering the frequent denier meme that the "lag" must mean that CO2 is a trivially unimportant tail of the climate dog.

  4. Eclectic @403, I have responded here.

    Response:

    [PS] Thanks for your consideration in  keeping conversation ontopic. Most appreciated.

  5. How can it be said that the temperature record is reliable when in June 2015, NOAA published a paper describing certain adjustments they had made to "improve" the data, and in so doing, they eliminated the 17 year warming hiatus that was troubling many climate scientists.  Not only that, but the temperature history during the last two decades of the 20th century was rewritten to double the rate of temperature increase. Assuming those adjustments were necessary to correct data errors, it opens questions as to the competency of the individuals involved in the data handling. Evidently, there were serious problems in the data gathering and processing that went on for 20-30 years, and it took an apparent slowdown in the warming to bring it to anyone's attention.  Allegedly, the problem is "fixed" now, but with the lack of competency that plagued the data handling process, how do we know the fix is any better than the original?

    Response:

    [JH] Argumentative/perjorative statement snipped. Please read the SkS Comments Policy and adhere to it.

  6. cosmoswarrior @405:

    here are the differences between raw and asjusted GHCNv3 data, as calculated by Victor Venema:

    The GHCN data was until recently the entire basis of the NOAA land only surface temperature data, and almost the entire basis of the GISS meteorological stations only temperature data.  The comparison applies for those sources also.  As can easilly be seen, there is almost no difference between the raw and adjusted data from 1980 forward.  Your claim that "the temperature history during the last two decades of the 20th century was rewritten to double the rate of temperature increase" is simply false.

  7. NOAAs conclusions about the non-existing "hiatus" have been confirmed by other studies using independent data. Zeke Hausfather from Berkeley Earth explains how they did it here and here.

    BTW, the Berkeley Earth surface temperature project was founded by physicist and former climate skeptic Richard Muller to address the most important objections the deniers had to the "official" temperature records. They constructed their own temperature record, which turned out to be very similar to the ones from NOAA, NASA and the British HadCRUT4.

  8. So where is all of this temperature data that shows the "hiatus" isn't real? It's obviously not the GHCN data shown in Comment 406.  As Tom Curtis himself points out "there is almost no difference between the raw and adjusted data from 1980 forward".  So where is this data with a big enough difference between the raw and adjusted values such that the raw data shows a warming hiatus but the adjusted values do not?

    Now, before you delete this question/comment and disable my login, I believe I am asking a simple, straight-forward question that should be easily answerable if in fact the adjusted data is what the elimination of the warming hiatus is based upon.  Therefore, if this comment is simply deleted before I receive a satisfactory answer to my question, I will proceed on the basis that no such data exists, and that eliminating the hiatus was based on politics and not science.

    Response:

    [JH] Please spare us the polemics.

    [TD] I can't make sense of your question. Your first sentence would match the rest of your first paragraph if your first sentence instead was "...that shows the 'hiatus' is real?" Tom Curtis showed you data (and you can download it yourself instead of taking Tom's word for it) revealing no such difference. The "hiatus" does not and never has existed.

    [DB] This user is just another sock puppet of serial spammer cosmoswarrior/coolearth; accordingly, their posting rights have been rescinded.  As will future iterations of this serial spammer.

  9. cosmoswarrior/coolearth/diehard appears to not like my pointing out @406 the gross error in his claim that "...the temperature history during the last two decades of the 20th century was rewritten to double the rate of temperature increase".  Rather than admit that gross error, he quibbles about the data source, and about the change in the NOAA temperature data set detailed in Karl et al (2015).  To deal with his quibbles, here is a comparison of raw and adjusted data in the new data set in figure 2 of Rove et al (2015):

    The top panel shows the difference between prior adjusted data set, and the new adjusted data set.  It is very clear that use of the new data sets make almost no difference to the trend.  In the bottom panel is a comparison of the new adjusted data set to the raw data set.  Post 1945 there is almost no difference, and in particular it is clear that claims that "...the temperature history during the last two decades of the 20th century was rewritten to double the rate of temperature increase" are at best massively misinformed, and at its source, a lie.

    With regard to the disappearing of the "hiatus", that comes about in Karl et al (2015) not because they use a new method of adjustments, but because they use two new data sets.  Specifically, they switch from ERSSTv3 to ERSSTv4 for marine temperatures, and from GHCNv3 to the ISTI database for land temperatures.  The later represents a switch to a larger database with a more extensive coverage.  It represents more data.  The change in ERSST versions involves, "...updated and substantially more complete input data from the International Comprehensive Ocean–Atmosphere Data Set (ICOADS) release 2.5; revised empirical orthogonal teleconnections (EOTs) and EOT acceptance criterion; updated sea surface temperature (SST) quality control procedures; revised SST anomaly (SSTA) evaluation methods;
    updated bias adjustments of ship SSTs using the Hadley Centre Nighttime Marine Air Temperature dataset version 2 (HadNMAT2); and buoy SST bias adjustment not previously made in v3b."  It's effect on the NOAA temperature record is discussed in detail by Kevin Cowtan here.  It has also been discussed by Zeke Hausfather as part of a more comprehensive discussion of the NOAA updates.

    Finally, the "hiatus" is not defined as a period of zero or negative trend in Global Means Surface Temperature (GMST).  Rather, it is defined as a period in which the zero trend is within the error margin of the observed trend.  As it happens, the long term trend has been within the error margin of the observed trend through out all periods considered to be part of the hiatus.  That means, logically, there is no more reason to consider the trend to be zero than there is to consider it to have continued unabated.  Indeed, given that all purported periods of the "hiatus" are parts of periods in which there is a statistically significant positive trend, there is more reason in those periods to consider them to be periods or warming rather than stasis.  In short, the "hiatus" was at best only a statistical artifact such that a small change in the observed trend (approximately one standard error) over the period of the "hiatus" makes it transparently an artifact.  That so small a change can make it "disappear" shows it to have been, at best, an artifact all along.

    Response:

    [PS] I think this serial spammer is data-resistant but thanks for clarifying the matter for the benefit of other readers.

  10. No, Tom Curtis. Your graphs do not satisfy my "quibbles" — not in the slightest. What I am looking for are the "corrections" that were applied to the original data (which clearly showed a warming hiatus) in order to eliminate the warming hiatus. These data adjustments, as I stated in a previous posting, totally eliminated the warming pause and about doubled the warming rate. Now, before negating me again on this claim and being too quick to delete this posting, be advised that this was part of the introductory statement made by Zeke Hausfather on the video Recent Ocean Warming has been Underestimated. In his words, "... they increased the amounts of warming that we have experienced pretty significantly. They roughly doubled the temperature trend since 1998 compared to the old versions of the datasets." So who am I supposed to believe, you or him!?

    Now from the email newsletters I get from the "denier" community along with a few online news articles about whistleblowers and NASA and NOAA fighting the Congressional investigation, I believe I have some insight as to why you can't come up with the dataset showing the adjustments that did away with the warming hiatus. NOAA simply refused to cooperate with the investigation and witheld the subpeonad email communications and scientific data. Since this was still during the Obama administration, the Whitehouse would not enforce their compliance. Therefore, the world may never know just what killed the hiatus at NOAA, and I'm supposed to accept their "data" as "overwhelming evidence with 97% consensus". — Give me a break! If this is your version of science, you can keep it!

    Finally, I would like an apology from you for your statement "Rather than admit that gross error, he quibbles about the data source, and about the change in the NOAA temperature data set detailed in Karl et al (2015)." We know now that my claim was not erroneous at all. Either that or Zeke Hausfather made the same "gross error". Also, I resent your use of the term "quibbles" as it gives readers the impression that my concerns are over trivia as opposed to the primary issue of assessing the amount of global warming we are experiencing.

    Response:

    [PS] More gross violations of policy from already banned user. No responses please.

    Update - this latest incarnation now removed. Why someone who has no intention of abiding by comments policy post here is mystery.

  11. I would like to comment on your responses to cosmoswarrior and diehard in their postings about the reliability of NOAA temperature data. First, in the response Tom Curtis gave to cosmoswarrior in @406, he showed the GHCNv3 data before and after the corrections, and pointed out that there was "almost no difference between the raw and adjusted data from 1980 forward". Tom Curtis then used this fact to argue that cosmoswarrior was incorrect in his/her statement about the data adjustments made in 2015 (which eliminated the "warming hiatus") also rewrote the temperature data for the last two decades of the 20th century. This is not an equitable comparison, however, since GHCNv3 was a land-based dataset only and the major changes had to do with the sea-surface measurements. Therefore, we cannot use this fact to argue that the statement by cosmoswarrior about "pause-buster" data corrections is "simply false" or that he/she is in "gross error".

    At this point, I don't believe the fact can be disputed that NOAA made major changes in temperature data in June 2015 which in fact eliminated the appearance of a warming slowdown after 1998. The writings and videos by Kevin Cowtan and Zeke Hausfather that you in fact post and reference discuss the affects of these "adjustments" on the temperature trends. Additionally, news of these sweeping changes, including rewriting of data (which at least most of us have never seen before in any scientific effort), caused a huge controversy in the entire climate science field and eventually prompted a Congressional investigation. Therefore, if cosmoswarrior and diehard are mistaken in their statements, they are far from being the only ones.

    Response:

    [PS] Try again - after you have read the comments policy.  Note, no sloganeering, no accusations of fraud. Check for accuracy of your premises (what you read on some denier site is likely wrong) and logic. Unless you think a telescope works best without wiping the dust off, you need provide evidence that adjustments to temperature record are scientifically invalid, not that you dont like the results.

    [DB] This sock puppet of serial spammer cosmoswarrior will not be rejoining this conversation.

  12. While strongly suspecting that moonrabbit @411 is yet another sock puppet, I will point out that my post at @406 exclusively criticizes cosmoswarrior/diehard/dieharder's claim @405 that:


    "Not only that, but the temperature history during the last two decades of the 20th century was rewritten to double the rate of temperature increase."


    As can be easilly seen from the graph @406, and the equivalent graph from Karl et al shown at @409 (panel b), the trend in the last two decades of the twentieth century, ie, from 1980 onwards, was not doubled when comparing adjusted to raw data.  cosmoswarrior/diehard/dieharder's claim to the contrary is indeed a gross error.  Somebody who cannot acknowledge even that, and who continuously misrepresents the argument made against his claim to avoid doing so in not amenable to reason.

    If they (and moonrabbit, on the assumption that is not just another sock puppet) cannot acknowledge even that gross error, or even correctly represent the argument against it, how on earth can they be expected to discuss reseanably the more subtle issues relating to the 1998-2012 trend (ie, the so called "hiatus").

    Response:

    [DB] Yes, this was just yet another tired, tepid sock puppet iteration of serial spammer cosmoswarrior.

  13. landdownunder @413:

    1)  Tony Heller (aka Steven Goddard), producer of the www.realclimatescience.com website is not a climate scientist, former or otherwise.  His qualifications are a Bachelors degree in Geology, and a Masters in Electrical Engineering.  So far as I can determine, he has never published a peer reviewed paper of any description.  He is well known as a serial misreprenter of data, a prime example of which is the gif which he produced, and you show.

    2) Heller's giff does not demonstrate any significant change in values.  Rather, it exhibits a change in the range of the y-axis from -0.6 to 0.8 for "NASA 2001" to approximately -0.85 to 1 for "NASA 2015".  That represents a 32% increase and accounts for nearly all of the apparent change in trend - particlularly post 1980.  An honest presentation of the data would have plotted both on the same axis, and ideally on one graph to allow direct comparison, like this:

    (Source)

    As can easily be seen, the temperature trend between 1980 and 2000 is nearly the same in all versions, and has certainly not doubled.  In fact, the GIFF is doubling misleading.  The 1998, 2000, 2012 and 2016 versions of the NASA GISS Meteorological Stations only temperature index are downloadable here (as also for the Land Ocean Temperature Index).  the 1979-1998 trends are, respectively 0.184, 0.134, 0.169 and 0.177 oC/decade.  You will notice that largest change is the 27.2% reduction in the trend from the 1998 to the 2000 version, followed by the 26.1% increase from 2000 to 2012.

    Clearly the history of changes is not one sided, indicating the scientists concerned are following the data.  Equally obvious is that Tony Heller has cherry picked an interval to show a rise in trend, even though the available history of adjustments results in a net reduction in the trend of the last two decades of the 20th century, not an increase.

    Returning to cosmoswarrior's specific claim, a 32.1% increase in the trend (2000-2016) is not a doubling of the trend.  Not even close, so even on your generous interpretation, that remains a gross error.

    3)  Unlike the AGW "skeptics", who focus on the facts of the changes without regard to the reasons, actual climate scientists focus on the reasons, which they detail in peer reviewed publications, and in the case of GISS, on site as well (see prior link).  One main contributor to the change in trend from for the meteorological stations index has been the increase in the number of stations.  The first version of GISS (1981) relied on just 1000 stations.  That increased to 2200 in 1987, and to 7200 in 1999 (between the 1998 and 2000 versions).  In 2005, a small number of stations in Antarctica were introduced, which was not a major increase in number, but very significant in improved coverage.  Finally, in 2016 the number of stations jumped to 26000.

    There have also been significant improvements in techniques, as detailed by GISS:


    "We have gone through the archives to show exactly how these estimates have changed over time and why. Since 1981 the following aspects of the temperature analysis have changed:


    • The simple procedure used in 1981 was refined as documented in Hansen and Lebedeff (1987), using 8000 grid boxes to allow mapping and analysis of regional patterns.

    • Surface air temperature anomalies above the ocean were estimated using sea surface temperatures from ships and buoys starting in 1995 as documented in Hansen et al. (1996).

    • Starting in the 1990s, the methodology took into account documented non-climatic biases in the raw data (e.g. station moves) and eliminated or corrected unrealistic outliers (Hansen et al., 1999).

    • Areas with missing data were filled in — using means over large zonal bands — rather than restricting the averaging to areas with a defined temperature change (Hansen et al., 1999).

    • A method was devised in 1998 and refined in 2000 to adjust urban time series to match the long term mean trend of the surrounding rural stations, Hansen et al. (1999, 2001). This adjustment uses the full data series to make the best estimate of the rural/urban difference and so can change as the time-series are extended (and more data comparisons are available). Starting in 2010 night-light radiance rather than population data were used to classify stations (Hansen et al., 2010).

    • Usage of water temperatures as proxy for air temperatures was more accurately restricted to areas without sea ice starting in April 2006."



    The merits of these changes in method can be argued, although they all seem like eminently reasonable improvements to me.  But if you object to them, you have to make that argument.  You cannot simply say that you do not like the result and therefore the methods are wrong - still less that they are fraudulent.  The later, however, is the method employed charlatans like Tony Heller.

    4)  The involvement of politicians in challenging the adjustments is in no way evidence of the scientific invalidity or otherwise of the adjustments.  It is evidence of where politicians think they can get political milage, either with there base or with their donors.  Curiously, the second largest category of donors of Lamar Smith, who led the congressional inquisition on Karl et al, was from the Oil and Gas industry.  Lamar Smith is not alone.  In 2016, the Oil and Gas industry made political donations to the tune of $103 million dollars, 88% of which went to Republicans.

    5)  Finally, you quote Zeke Hausfather as saying:


    "... they increased the amounts of warming that we have experienced pretty significantly. They roughly doubled the temperature trend since 1998 compared to the old versions of the datasets"


    and go on to suggest, "...is also consistent with cosmoswarrior's statement".  However, cosmoswarrior's statement was explicitly about the last two decades of the 20th century (1981-2000), not the interval from 1998-2012 that Zeke Hausfather was talking about.  His comment was, therefore, entirely irrelevant to cosmoswarrior's eggregiously false claim.  More importantly, the 1998-2012 trend "roughly doubled" not because there was a large increase in the trend, but because the trend was low.  The change in trend over that period was from 0.039 C per decade to 0.86 C/decade, a change of approximately half (63.5%) of one standard deviation of the error of the new trend as determined on the SKS trend calculator.

    Following the logic of the advocates of the existence of a "hiatus", that is no change at all.

    Response:

    [PS] This excellent rebuttal of Goddard's nonsense stands. However, for those confused by its context, it was a response to yet another sockpuppet of comicwarrior et al which has been deleted. This denier's comprehension skills dont extend a comments policy let alone serious science so unfortunately I think Tom's points will have been lost on him/her completely. Other visitors might find this response useful however.

  14. Tom:
    It’s also worth noting that the land only temperature record from Berkeley Earth shows slightly more overall warming than NASA!
    Data sources here and here.

    Global land temperature

  15. I reviewed with interest the comments made to cosmoswarrior et. al. in comments 405-414. Tom Curtis points out in comment 406 that there is almost no difference between the raw and adjusted data from 1980-present for GNCNv3 data. Examining your plot, I would have to say I fully agree. Similarly, you showed plots of the new corrections, old corrections, and uncorrected NOAA temperature dataset in the figures in comment 409. Again, I would have to agree there is not much difference between three from about 1940 forward.

    There is one statement you made, however, that needs correction. This is in comment 413(2) where you state:

    Heller's giff does not demonstrate any significant change in values. Rather, it exhibits a change in the range of the y-axis from -0.6 to 0.8 for "NASA 2001" to approximately -0.85 to 1 for "NASA 2015". That represents a 32% increase and accounts for nearly all of the apparent change in trend - particlularly post 1980.

    I downloaded this animated .gif file myself and extracted the individual images for 2001 and 2015. I then compared scales by copying and pasting the two axises from the 2015 image onto the 2001 image, and then sliding each axis from the 2015 image next to the corresponding axis of the 2001 image. It turned out that the horizontal axises of the two images were identical and the scale of the vertical 2015 image was slightly smaller than that of the 2001 image. Therefore, the actual slopes of the data plot for 2015 are slightly higher than what they appear in the plot image. I would have shown this image, but I am not sure how to do it just yet. While this data is not important for the points I want to make and carries no credibility with you, I thought I should point out the error since the topic came up recently.

    From what you have pointed out in your most recent comments, it seems that you have debunked the myth about NOAA eliminating the "warming hiatus" in its paper of 2015. What happened was that we had a warming trend from about 1980 until 1998 when the warming rates were greatly reduced. We then continued on that level trend until 2015 when NOAA announced that they had shown with their "corrected" data that the warming hiatus never existed. Contrary to NOAA's claims, however, you pointed out that the corrected and uncorrected data are very nearly identical and therefore could not have eliminated the hiatus. This means, of course, that the hiatus not only existed back in 1998 but continues to this day.

    So thanks for your inputs, Tom Curtis. You have been most helpful to us "climate contrarians" in making our case.

    Response:

    [DB] Pathological liar and sock puppet of serial spammer cosmoswarrior has recused himself from further participation here in this iteration.

    [PS] Also someone that seems absolutely determined that deniers have no concept of logic, critical thought or comprehension when it comes to trying to defend a preconceived position.

  16. (-snip-)

    Response:

    [DB] Serial sock puppet of serial spammer cosmoswarrior snipped.  Please ignore this user.

  17. RobJones @416, if you are going to accuse me of lying, it behoves you to use my actual words.  I did not talk about a change in scale, but a change in the range of the y-axis.  Specifically, I said:

    "Heller's giff does not demonstrate any significant change in values. Rather, it exhibits a change in the range of the y-axis from -0.6 to 0.8 for "NASA 2001" to approximately -0.85 to 1 for "NASA 2015". That represents a 32% increase and accounts for nearly all of the apparent change in trend - particlularly post 1980."

    Nearly all of the apparent change in trend post 1980 is a result of the warming trend continuing for another 14 years, a fact obscured by Heller's method of presentation.  This is evident when you simply overlay the data as in the graph I showed.  By changing the range of the y-axis between graphs, Heller creates an optical illusion, without which his case falls to pieces.

    As it happens, Heller's scales are also not identical, as is shown by your graph, and as I have independently confirmed.  This can be seen by noting that the decimal points of the two graphs are aligned at 0.2 on the y-axis, but not aligned at 0.8.  Thus, you have conveniently demonstrated that Heller also changed the scale.  The effect, however, is minor and works against his preferred indoctrination, and so can be ignored. 

    Continuing on, you write:

    "I compared these plots with those used by Tony Heller in his .gif animation, and except for scale, they were identical. BTW, these are the datasets I am referring to when I talk about the doubling of warming trends with the "corrections" of 2015. The statement bu Tom Curtis

    "It is very clear that use of the new data sets make almost no difference to the trend."

    obviously does not apply here as substantial data re-writing was done for the entire 20th century, most of which should not have been touched."

    First, thank you for confirming that your current account is a sock puppet by referring to your prior talk about doubling.  I note that you talked about a doubling of the trend in the last decades of the 20th century, and clearly there is no doubling of between the lowest and the highest trends among different GISS versions as shown in the graph I show.

    Second, the specific changes in methodology detailed @413 are applied across the entire century.  More importantly, when additional stations are added, they can have data across any period of the record.  Consequently, on both accounts we would expect revisions going as far back as 1880.  Once again, if you have a problem with the methods, criticize them.

    Finally, I note your hypocrissy in being shocked that I should accuse Heller of lying (even though I didn't); while hapilly defending Heller whose whole career in climate science has been based on claims that climate scientists are lying; a claim you appear to make in your following post ("field of study isn't already riddled with corruption").

  18. Serial Sockpuppet (of #416) seems to take very personally the criticism of Mr Heller.

    The graphs he alludes to, both demonstrate a skyrocketing of global temperature during the past 2 decades.

    — So what on Earth is the point he is trying to make, other than a pointless persistent peevishness?

    The world is heating up rapidly: regardless of deniers.

    (Moderator, please abridge or delete my post, at need.)

  19. Tom Curtis — Your ineptness with these graphs never ceases to amaze me. Take another look at the figure below before you delete it again.

    Figure comparing axis scales on the NASA 2001 and Nasa 2015 plots

    Notice that the tick marks of the two horizontal axises align perfectly with each other as I showed with the short green lines connecting them. Similarly, the tick marks of the pair of vertical axises also align perfectly. Therefore, the scaling of both the horizontal and vertical dimensions of the two plots are identical. The reason the decimal points may not align as well has to do with the different font sizes of the plot labels, and NOT the data or scaling. Therefore, Tony Heller's plots and animated .gif file still stand as a fair presentation of how the 2015 "corrections" rewrote temperature data since 1880.

    What happened in the case of this figure is a prime example of your long history of deleting my comments, giving your faulty understanding of what I said, and then trying to discredit me on the basis of your spin on the story instead of what I actually said. Can we say "strawman tactics"?

    At this point, it is quite clear to me that you are either totally incompetent or intentionally deceptive in your position, and in either case, for me to have any sort of intelligent discussion with you is simply not possible.

    BTW, I saved screen snapshots of my postings before you and any "moderators" had a chance to remove them. Therefore, if "push comes to shove", it won't be just your word against mine as to what was said.

    Response:

    [PS] TC is not a moderator. Posts removed because sockpuppet of someone who cannot comprehend comment policy and let alone the science.

    If you wanted to discuss science (which you are apparently incapable) then you needed have heeded the comments policy. No exceptions and no further chances.

    [DB] Posting rights rescinded due to boringly iterative sock puppetry.

  20. The hangup that SkepticalScience.com has in regard to temperature data is that you are exclusively using datasets at least as current as 2015, all of which are tainted by the 2015 adjustments. No wonder you make statements such as

    "It is very clear that use of the new data sets make almost no difference to the trend."

    If you want to do a fair assessment of the impact that the 2015 corrections had on the historical temperature data, you must dig up those archived datasets recorded before 2015. Otherwise, you just go around in circles claiming that the warming hiatus is over or never was while the corrections "make almost no difference to the trend". Well, if the corrections make no significant difference in the trend, and the current trend is hiatus, then wouldn't we still be in hiatus?

    Response:

    [PS] Removed pending moderation investigation.

    [DB] Posting rights rescinded due to flagrant sock puppetry.

  21. Eclectic — As I explained in a previous post, which SkepticalScience took down, I checked on Heller's sources and scaling of his graphs, and it turns out that his presentations stand up to scrutiny whereas the those from SkepticalScience don't even make sense.  That's why I have defended Heller in his work.  There is nothing personal about it.

    Response:

    [PS] Removed while account investigated.

    [DB] Iterative sock puppet (number 11) of serial spammer cosmoswarrior has been removed from further participation in this venue.  As will all of your future such.  It might profit you better to seek a more amenable village to infest.

  22. Moving on to a more sensible discussion. Surely the instability in the reconstructed temperature record is a legitimate cause for concern?  Ole Homlums has published a lot of data on the adjustments and seems to come to the reasonable conclusion that:

    "Based on the above [detailed charts of changes over time ]  it is not possible to conclude which of the above five databases represents the best estimate on global temperature variations. The answer to this question remains elusive. All five databases are the result of much painstaking work, and they all represent admirable attempts towards establishing an estimate of recent global temperature changes. At the same time it should however be noted, that a temperature record which keeps on changing the past hardly can qualify as being correct. With this in mind, it is interesting that none of the global temperature records shown above are characterised by high temporal stability. Presumably this illustrates how difficult it is to calculate a meaningful global average temperature. A re-read of Essex et al. 2006 might be worthwhile. In addition to this, surface air temperature remains a poor indicator of global climate heat changes, as air has relatively little mass associated with it. Ocean heat changes are the dominant factor for global heat changes."  

    Source  (http://www.climate4you.com) 

    Response:

    [DB] "Surely the instability in the reconstructed temperature record is a legitimate cause for concern"

    You document no instability, so you posit a strawman.  Further, Humlum's nonsense has been debunked in this venue before (here and here, notably), so if you wish to address anything from him, take it to one of those threads.  Not here.  Further, no matter where you place comments at Skeptical Science, the Burden of Proof is on you to bring credible evidence to support your claims.

    Further, your supposed quote is actually from here.

  23. Hi DB: I apologise for not adding the final extension to the link.  However now you have added the correct link, other users can see Humlums extensive analysis of administrative changes in all the major data series. This hardly constitutes a straw man. And how does making a generic attack on  "Humlum's nonsense" contribute to this debate?  I have cited his extensive charts on instability in the reconstructed temperature data and you respond with two completely unrelated points made on other data presented by humlum. Do your sites standards on "ad-hominem" and provision of proof apply to moderators? If not I'm probably wasting my time. 

    Response:

    [TD] Tom Curtis's comment is educational. Also Zeke's post.

    [JH] Moderation complaint snipped.

  24. Mark:

    The point is that Humlum has no credibility as a witness.

  25. Er, MIke, not Mark. Sorry.

  26. Mike... It should be noted that most of the regulars here are very familiar with Humlum's work. He really isn't credible. On this topic in particular he's presenting a rather absurd notion. Yes, all the various data sets show different figures, but they only vary in a minimal way, and the differences between them certainly don't invalidate them in any way.

    To the question, "Is global mean temperature rising?" there can be no doubt. All the data sets say yes. We get that from all the surface station data and from all the satellite data. The variances between them are merely a function of how each group processes their data.

    It's interesting that Humlum states that ocean data is the better indicator, and he's right. And when you look at ocean heat content you get the exact same answer. The climate system is accumulating heat.

  27. Thanks for the measured response Rob. My question was a serious one - my reading of Humlums data on this narrow point is not that there is any doubt about the fact of warming, but the data revisions - especially those before the satellite record - would seem to create some uncertainty around the long term rate of the warming.  

  28. Mike Evershed @427.

    For anyone who takes the time to examine Humlum's work, it is evident the man is a prolific source of nonsense and that he does not take any rebuttal seriously because he doesn't care. Note his Figure 3 on the web-page providing your primary quote - it is addressed in this SkS rebuttal here but in response Figure 3 has not been properly corrected by Humlum. Rather, now we find his Figure 3 is simply "not showing the post Little Ice Age temperature increase."

    The logic of the Humlum quote you present @422 is making three assertions. Firstly that it is difficult to create "a meaningful global average temperature" and while the word "meaningful" is a bit odd, it is correct to say that it is not a trivial task to create a global surface temperature record. But, as shown in the links @423Response, this work has been done.

    Secondly, Humlum references Essex et al (2006). Yet Humlum does not set out in any way what it is in this paper he is referring to. He says it is "an interesting discussion of the whole concept of calculating an average global temperature" and that "a re-read of Essex et al. 2006 might be worthwhile." The reference by Humlum is thus nonsense.

    Thirdly, Humlum argues that OHC is a better measure of global temperature which all would agree is true.

    So, stripped of its nonsense, Humlum's quote is not supporting your suggestion that there is "some uncertainty around the long term rate of the warming," that is uncertainty beyond that declared within the work that created them.

  29. "but the data revisions - especially those before the satellite record - would seem to create some uncertainty around the long term rate of the warming."

    I dont get the logic here. Does cleaning the lenses on your camera increase the noise in the image? The "revisions" are results of in depth, peer reviewed methodologies to put station records onto a common basis which reduces the uncertainty, not increases it.  

    I find your faith in the satellite data unwarrented too. See this myth for which has the greater uncertainty. Let me ask this, how much of Humlum stuff do we need to debunk for you before you write it off as misleading (to be polite)? 10, 20? or will you keep looking through that and other pseudo-skeptic sources in hope of finding better news?

  30. "Thirdly, Humlum argues that OHC is a better measure of global temperature which all would agree is true"

    I am guessing Humlum support for OHC was at same time as Peikle was pumping it, believing it would show less warming. Wonder if he still as enthusiastic? Peikle went very quiet about it. OHC is a good measure of energy imbalance - and the data set is considerably less noisy than surface temperature. However, the surface temperature for all of its noise and measuring issues is about where we actually live.

  31. Hi Scaddenp (re post 429) sorry for the delay (unfortunately I'm still working).  The uncertainty arises from the issue whether the adjusted baseline temmperature data for (say) 100 years ago is reliable. With modern data we have a much better chance of making resaonable adjustments (we've still got the equipment, we can be more certain of field conditions etc). But adjustments to very old data by their nature must be more uncertain.  And the correct  analogy is not "cleaning the lenses on your camera" but "touching up your picture to show what you believe it would have shown had the camera lens not been dirty". That is a much more uncertain business. 

    Response:

    [TD] In addition to the two links I gave you earlier, see the post by Scott Johnson. And a post by Dana. Tom Curtis informed you that many of the "adjustments" are not to individual records, but to the indices by adding vastly more stations. That type of adjustment does not rely on any of the factors you now are complaining about. As Scaddenp requested, be specific in your questions and objections, responding specifically to the info people are providing you with. They are responding specifically to your specific claims, and you must return the favor. Else you are merely sloganeering, which is not welcome on this site.

  32. Okay, noone is doubting that error bars on temperatures increase the further back you go - I hope you have seen the intermediate and advanced tab - but that does not really give you much uncertainty in the warming trend. Furthermore, cleaning reduces the errors. And frankly, it is cleaning the lens. There is no pre-conceived believe in the what unadjusted temperature should look like. The methodologies for sharpening the record are very well documented. Which corrections or methodology do you believe would bias the corrections one way or other, and why? No hand-wavy answers please.

  33. Let me be a little more specific. If, over time, a station changes the Time of Day for reading, this produces a well documented change to the temperature average. Given that there is a well researched methodology for correcting a temperature measured with one ToD to another basis, which is going to be the more reliable dataset - the uncorrected station record with different countries using different practises in different periods? Or the one with every station corrected to the same basis? Likewise, some stations become surrounded by urban areas with again, a well-documented increase in temperature from the urban effect not a climatological one. Is the record with an uncorrected mix of rural and urban stations, a more certain estimate of climate than one in which the urban effect has been removed by cross-pairing with rural stations?

  34. Mie Evershod,

    Are you aware that the adustments of the old records have resulted in a substantial lowering of the amount of warming measured?  Any uncertaity introduced by the adustments have to be in the direction of increased warming, not decreased warming.  That means the problem would be greater than determined using the adjusted data.  Humlum and others claim that they do not trust the adjustments but then refuse to use the unadjusted data for analysis because it shows a greater problem.  That is contradictory and hypocritical.

    The unadjusted data are still  available for use by anyone who wants to use bad data.  (link to Guardian article comparing adjusted and unadjusted data).  If you do not trust the adjustments go for it with the old data.

  35. Thanks to moderator TD, Scaddenp, and Michael Sweet for replies. I have looked up moderator TD's references. But the problem I have is not whether individual adjustments, or homogenisation techniques are reasonable.  Nor do I worry that there has been fraud on the part of climate scientists (though I suppose that is possible - scientists being human). Nor do i think that reverting to raw data would be better. My point as someone who is scientifically trained is that the more adjustments we make and the more data transformations we perform the greater the risk we run of making errors. Also, and more seriously, the more choices we make about which adjustments to apply, and how to apply them, we increase the risk of something called "confirmation bias".  (The basic idea of confirmation bias is well known and adequately described in wikipedia - so I hope I may be excused providing a reference). So for me the most important point made in the replies is Michael Sweet's: i.e. that the adjustments of the old records have resulted in "a  substantial lowering of the amount of warming."  Does anyone reading this know where I can find the published scientific data on this - particularly in the surface air temperature? I have seen claims made both ways: leaving Humlim aside I have also seen this: https://wattsupwiththat.com/2016/04/24/updated-do-the-adjustments-to-land-surface-temperature-data-increase-the-reported-global-warming-rate/

    Response:

    [TD] You have been pointed to graphs of raw versus adjusted temperatures multiple times and claim to have read them, yet now ask for a pointer to that information.

  36. Mike Evershed @435, your comment exhibits a gross misunderstanding.  The various versions of GISTEMP LOTI (for example) do not apply additional adjustments on to already adjusted data.  Rather, they apply refined versions of existing adjustments to the raw data.  A classic example of this is the switch from switch to using night light data to determine urban areas inorder to apply the Urban Heat Island (UHI) adjustment.

    If you adjust for the UHI using one method, and then start adjusting it by another method, there is no a priori reason to think that the second method will be worse than the former method.  Indeed, given that the second method is based on improved statistical analyses of the effect, or improved subsidiary data (eg, night lights), it is likely that the second method will improve on the first.

    Your further assumption that any adjustment will probably be worse than data known to be contaminated by extraneous effects (time of observation, station moves, etc) is also (to put it very kindly) dubious.

    Finally, I am interested in your opinion of orbital decay adjustments to satellite temperature data.  Is it your opinion that satellite temperature products should just show the unadjusted data as per the top panel of the following graph?

    And if not, how are we to believe you objections to adjustments to the surface temperature data are principled rather than opportunistic?

  37. Mike @435... I'd suggest taking everything at WUWT with a large dose of salt. Anthony's only litmus test for posting articles on his site is whether he thinks it casts doubt on climate science, without any for validation or review of the materials. You really have to dig in to anything you read on that site. (And that's not to say you shouldn't dig in to materials posted here, but SkS takes on more of a review process behind the scenes for the articles posted here.)

  38. And, relative to the Bob Tisdale article you referenced...

    1) I congradulate you if you can actually get through reading an entire Tisdale article. He's a borish and convoluted writer, at best. Great reading if your purpose is putting yourself to sleep.

    2) Most of the charts he's presenting actually support the fact that, for the modern era (post-1960), adjustments do not have a substantive effect on the conclusions of the land data. 

    3) The bigger challenges are with older sea surface data where methods of collecting the data changed over time. Those adjustments have resulted in lowering the long term temperature trend relative to raw data.

    4) I definitely do not understand your rationale on confirmation bias. There are multiple groups processing the data and they're, essentially, ending with results that are in agreement. If there were a significant bias being introduced you'd expect that to be evident across multiple groups. The idea that all the groups could have the same bias, even though they're using different methods, seems extremely unlikely.

  39. Rob Honeycutt @438,

    Additional to your points gleened from "borish Bob Tisdale," it should be mentioned that the adjusted global land surface air temperature anomalies over their full record do result in increased linear trends relative to their 'raw data' trends but only when calculated over the full record (Bob's figure 1) and importantly all these adjustments that are global in land coverage (note CRUTem4 is a long way from global in land coverage and Bob Tisdale likely misrepresents the raw data it uses); these global land records provide adjusted results that are consistent. Given the adjustment methods are so different, that they give consistent result suggests Mike Evershod's specific worry about errors ("the more adjustments we make and the more data transformations we perform the greater the risk we run of making errors") is unfounded.

  40. Zeke Hausfather, one of the scientists on the Berkely Earth Surface Temperature (funded by the Koch brothers) wrote a detailed discussion of corrections on Carbon Brief.  I like his writings since he is obviously very familiar with the data since he publishes on it, he works for skeptics so it is difficult to see him as part of a conspiracy on AGW and his articles are easy to read.  You can Google his publications to get peer reviewed discussions of corrections.

    Others will give you better references than me so I will probably not post again. Read less "skeptical" material if you want to be informed, WUWT is especially bad.

  41. MIke Evershed @ 435: "My point as someone who is scientifically trained is that the more adjustments we make and the more data transformations we perform the greater the risk we run of making errors."

    Well, the way to deal with that scientifically is to read the papers that describe the adjustments and transformations, and why they were done the way that they were, and what evidence was presented to support their use.

    If you discover a questionable adjustment, and can demonstrate that a different - and equally reasonable - alternate approach provides a significantly different output that affects the conclusions, then point it out. If all you have is "there might be an error, but I don't know where", then all you have is an argument from incredulity. A "greater risk" of making an error does not meant that there is one. (Note: "making an error" is not the same thing as "not everything is known". Knowledge is always incomplete.)

    ...and anything I've seen presented at WUWT or similar "skeptic" blogs fails the "and equally reasonable" test, because they invariably involve explanations that require overthrowing major fundamentals of physics, cherry-picked data,  improper statistical analysis, flawed logic, etc. There is your source of errors.

  42. Mike, call me completely unconvinced. We use a number of very complex instruments. Over the years, both accuracy and precision have improved even though the fundimental measurement has not. This is due to ever increasing complexity of processing and correction between raw detection and reported result.

    Modern seismic processing has also become increasingly complex. Talk about torturing the data. Dont tell an oil explorer that the uncertainty in the depth to a reflector has increased because all that fancy processing makes errors more likely. Funnily enough scientists actually test this stuff and publish the methodology for everyone to examine.

    On the other side, faced with an unappealing set of data, instead of finding fault with the methodology and publishing alternatives, all we find is dark mutterings about scientists motives and accusation of manipulating the data, which shows a laughable ignorance about science, scientists and science funding. Since UHI and SST adjustment corrections (the biggest adjustment to the global surface temperature recored) reduce the warming trend, if scientists are trying to defraud the public, they are making a rotten job of it.

    The graphs on the advanced tab also show that adjustments are tiny compared to trend. Are you actually seriously suggesting there is a chance that surface temperatures are not actually warming? Ice melt and sea level rise are also somehow an artifact?

  43. I am grateful for the thoughtful responses of site participants (posts 436 to 442). Michael Sweets reference to Zeke Hausfather's article was particularly helpful and I'm beginning to see some light at the end of the tunnel. It looks as though the "denialist" sites are mostly referencing either the land surface air temperature data where revisions to older data do increase the warming trend (but only moderately so) or the modern period adjustments where again they increase the trend (but only slightly so), while sites supporting the consensus focus on the either the sea surface record or the overall record including sea surface temperatures where the adjustments reduce the long term warming trend (and significantly so).  As to the questions I have been asked - I don't dispute the climate is warming and I don't think the data adjustments represent fraud - but I am trying to get a handle on how reliable the consensus view is, and on this thread how reliable the warming data is. As to my concern about confirmation bias, I agree that the existence of different groups working on the data problems reduces the risk, however as all of them subscribe to the consensus view, and defend the anthropogenic warming hypothesis the risk of confirmation bias cannot be totally discounted.

    To quote an expert in the field: "A great deal of empirical evidence supports the idea that the confirmation bias is extensive and strong and that it appears in many guises. The evidence also supports the view that onceone has taken a position on an issue, one's primary purpose becomes that of defending or justifying that position. This is to say that regardless of whether one's treatment of evidence was evenhanded before the stand was taken, it can become highly biased afterward."   http://psy2.ucsd.edu/~mckenzie/nickersonConfirmationBias.pdf. Nickersons discussion of confirmation bias in science at the end is particularly interesting - including the observation that the strength of science lies in vigorous challenge to hypotheses.

     

    Response:

    [TD] People who are interested in global temperature look at the temperature of the globe. The whole globe. Land and water. Because that is the definition of "global."

  44. "however as all of them subscribe to the consensus view"

    Um, this isnt politics. You arrive at a consensus you dont start with one. Also BEST was started by Muller as was skeptical of the record with Koch funding. Anthony Watts said  “prepared to accept whatever result they produce, even if it proves my premise wrong.” That was until it confirmed the existing temperature records. So definitely not "all of them".

  45. It is also extremely hard to understand quite point you are trying to make. It feels like a fairly desparate attempt to find a reason to be doubtful of the temperature record with no actual basis at all. Do you comment on JPL sites about the dark side of the consensus on gravity might result in satellites off course? Or complain that maybe it is okay to build houses on faultlines because after all the geological consensus on earthquakes might be subject to confirmation bias?

  46. Mike Evershed @443.

    Your quote concerns confirmation bias generally and is not specific to the scientific process. Nickerson (1998) 'Confirmation Bias: A Ubiquitous Phenomenon in Many Guises'  does address things scientific (no mention of climatology) and a little more fully than he does witch-hunting. As I see this as off-topic, I will be brief.

    The accounts given of Conservatism among scientists, Theory persistence, Overconfidence and Unity in science I would suggest apply to the AGW denialists rather than the AGW proponents. Science works hard to root out Confirmation Bias. I see no difficulty in taking on board an aberrant theory that would disprove AGW, but only if it has merit. AGW denialists cannot say the same for the science they attempt to overturn, science that does have merit. Yet they do have a role in science (but not in public), using their denialist viewpoint to rattle the cage, but in doing this they have failed to produce any aberrant theories that have any merit, so far.

    Note that the examples given by Nickerson are about big issues that make-or break theories. (I should say here that I am not entirely happy with some of his accounts.) As the adjustments to global temperature series we discuss here do not lead to any make-or-break situations, I don't see there is a situation where confirmation bias would begin to operate. But looking from a denialist viewpoint, chipping away at the temperature record does assist the anti-AGW arguments, not least by spreading doubt over the entirety of all temperature records.

  47. And further to my earlier comment, there is plenty of people out there with hostile views and, for fossil fuel companies where proposed climate action is a threat to shareholder value, the funds and scientific muscle to create their own homogenized temperature series. They could also challenge the papers that details the homogenization methods if they could find errors. The lack of any such papers would suggest that noone has found a real problem. I cant imagine Exxonmobile pushing a paper "the scientists were right" if they did such a study (and we know their scientists have looked). All we get is innuendo which sits fine for an audience with their own ideological biases seem to have shut down their critical faculties if they ever had them.

  48. Confirmation bias. Of course there is always some risk of this, and its normal to look for evidence that supports an idea, but this doesn't dominate things. People are aware of the risk of confirmation bias, and contrary evidence will be thrust on people by other scientists wanting attention. Science has a habit of bringing all the evidence out in the open.

    The point is the global land ocean temperature trend over the last 100 years has been adjusted down, and for sound reasons. This is strong evidence that confirmation bias has not corrupted the temperature data. I would suggest conclusive evidence for all practical purposes.

    You would think this simple thing would end the debate on the issue, but no the denialists will rant on about it for decades and decades.

  49. Thanks Guys. In view of the discussion above, I would agree that the global temperature record (sea and land) is the better measure, and because adjustments to the sea surface data rduce the long term growth trend and there are several groups working on the problem of past reconstruction, the risk of confirmation bias causing significant problems is small. That leaves the issue of "is the warming anthropogenic" (but that is for another thread and another time). Thanks especially for the courteous replies to what has been an attempt to genuinely explore the issue. 

  50. Sorry - should have added that I found the points about Berkley Earth starting from a sceptical position and the lower risk of confirmation bias around adjustments which are not theory breaking to be good ones.

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