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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

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 201 to 250 out of 523:

  1. The so-called "Surface Stations Project" is a pile of idiotic nonsense that is of use only to those defined by Trenberth as "fools and charlatans." It has been proven irrelevant frome early on by the ones interested enough to follow up on it with real data analysis. It is not worth bothering with.
  2. #199 dana1981 at 09:08 AM on 27 May, 2011 But the presence of a DTR trend from 1950-1980 somehow doesn't mean the warming during that period was caused by GHGs. WTF?? There was in fact no warming between 1950 and 1980. Especially since it requires ignoring all other anthropogenic fingerprints Whenever you do not know what to say, start talking about something else. After all that's the way science is done. Or was it politics?
  3. #200 Albatross at 09:21 AM on 27 May, 2011 Does your silence indicate that you implicitly agree that you fabricated the phrase "but the fast increasing DTR"? Please substantiate your claim or admit that you made it up. Try reading the thread every now and then. It was KR quoting Braganza et al 2004, who said "observed diurnal temperature range (DTR) changes are actually much larger than predicted by models". It's a pity it was fabricated.
  4. Berényi - Then you have clearly misread the information I provided. "...observed diurnal temperature range (DTR) changes are actually much larger than predicted by models" (emphasis added) And you then failed to read the quote about the data: "This trend is due to larger increases in minimum temperatures (0.9C) than maximum temperatures (0.6C) over the same period." The DTR has reduced over this period, BP - you've read into it what you wanted, and not encompassed the entire quote. Which means, apparently, that you did not read the paper, either.
  5. #201 Philippe Chantreau at 10:04 AM on 27 May, 2011 The so-called "Surface Stations Project" is a pile of idiotic nonsense I see. Checking the quality of a measurement system is "a pile of idiotic nonsense" along with NOAA directive 10-1302 of course, Requirements and Standards for NWS Climate Observations. Is it some innovative new trend in science?
  6. [DB] More cherries for BP Come on. Until 1943 there was a single GHCN station south of 60S, BASE ORCADAS (-60.75 -44.72). Therefore the huge 1950-1980 positive temperature anomaly in the south (relative to 1919-1949) is entirely believable, isn't it?

    [DB] Curious, that the temperature records show an inexorable rise every single year, isn't it? ;)

    Let us not focus on the few cherry-flavored flat or declining spots lest we miss that overall rising signal in the noisy background:



  7. Berényi Péter @197, the diurnal temperature range data for Australia are taken from the Australian high-quality climate site network, which has been vetted for the quality of the stations, with stations rating poor(4) or very poor(5) on a five point scale having been removed from the network. I have seen some attempts by Australian deniers to question the network, and they are pathetic. Indicative of how desperate they are, they have argued that one outback site should be classified as urban because it is located near some graded runways, ie, because it is near (within 50 meters) of exposed dirt in an area which is 80% exposed dirt. is a discussion of another site they considered to be "urban". Had there been substantial issues to raise, I'm sure the deniers would have latched on to them. By inference, therefore, the genuine efforts of the Bureau of Meteorology to maintain high quality meteorological data have paid of. Further, aerosol optical depth is not well quantified, and indirect aerosol effects on cloud albedo are even less well quantified, but aerosol emissions are well known. Therefore, whatever the net aerosol forcing for a given aerosol load, we know that it increased from the 1950's through to the 1970's, decreased there after, and has been increasing again over the last decade:
  8. Berényi Péter @206:
    "Come on. Until 1943 there was a single GHCN station south of 60S, BASE ORCADAS (-60.75 -44.72). Therefore the huge 1950-1980 positive temperature anomaly in the south (relative to 1919-1949) is entirely believable, isn't it?"
    We should also note that: 1)There was also a very large whaling fleet operating in Antarctic waters; and 2)With the exception of water near the West Antarctic Peninsular, and hence Orcadas Base, the anomaly south of about 60 degrees is not shown in the anomaly map you are objecting to. Your objection, therefore, is without substance.
  9. #208 Tom Curtis at 14:01 PM on 27 May, 2011 With the exception of water near the West Antarctic Peninsular, and hence Orcadas Base, the anomaly south of about 60 degrees is not shown in the anomaly map you are objecting to. But it is shown in the accompanying "zonal mean" graph (with no error bars whatsoever). Your remark, therefore, is without substance.
  10. Berényi Péter @209, the accompanying "zonal mean" graph is exactly that, an accompanying graph. It is not published by GISS apart from the relevant map which is hte primary data; and nor was it published apart from it here. As such people seeing it are unlikely to be confused into thinking the zonal mean from 60 to 80 degrees south represents anything but the obvious measured anomaly rather that the equally obvious grey unmeasured areas. Further, the important thing is the 0.05 global mean anomaly between the respective periods. If you think noticing a large number of temperature measurements where you claim there was only one, and noticing that no claim was made of measurements in unmeasured areas contrary to your claim is without substance, then no wonder you are a denier. However, seeing you object to that map, consider the following which, as it compares 1940-1960 to 1970-1990 is more relevant to your claim of no warming between 1950 and 1980. Notice that the anomaly is 0.08 degrees C. Or perhaps you would prefer a simple comparison of 1950 with 1980 which has a 0.29 degree c anomaly. Clearly you claim is false. As this post shows that, you will no doubt consider it also without substance.
  11. If BP is refering to Anthony Watts' miserable operation, I stand by my statement. There is data analysis to substantiate.
  12. BP @203, Try reading the thread every now and then. It was KR quoting Braganza et al 2004, who said "observed diurnal temperature range (DTR) changes are actually much larger than predicted by models". It's a pity it was fabricated." Actually BP, you need to read very carefully what you wrote @191. I know what Braganza found, and KR's reading of the paper @186 is correct. Braganza (2004): "Observed DTR over land shows a large negative trend of 0.4C over the last 50 years that is very unlikely to have occurred due to internal variability. This trend is due to larger increases in minimum temperatures (0.9C) than maximum temperatures (0.6C) over the same period." Inconvenient for you and Watts is that Fall et al's work brings the models into closer agreement with the observations. Watts loses again. Also, the models did not predict a statistically significant decline over much of the contiguous USA between 1950 and 1999, consistent with the findings of Fall et al. (see Fig. 3 in Zhou et al. 2010). Watts loses again. What was fabricated? By whom? The only things that was possibly fabricated was the following claim made by you @191 when you said: "Or, alternately, you can insist the temperature record is reliable, but the fast increasing DTR is inconsistent with model predictions." Do you see that word "increasing" that you typed? Perhaps you meant to say was something like "the rate of decrease in observed DTR is greater than that predicted by the models over the USA". Do you not read what you type before disparaging others? Again, if anything, Fall et al's work actually brings the models into closer agreement with the observations over the USA, and one of the paper's authors Dr. John Nielsen-Gammon agrees with that. Another "skeptic" bubble burst.... KR, @186 "The issues with day/night temperature range are quite different - you might profitably look at Braganza et al 2004, who note that observed diurnal temperature range (DTR) changes are actually much larger than predicted by models, most likely because of insufficient accounting for temperature driven cloud increases in those models."
  13. Read this recently: manipulation the GISS gets away with every day. You see, although the GISS receives temperature readings from thousands of global stations, it uses only a fraction of them. Unbelievably, the GISS still fills out the thousands of spreadsheet cells, using figures from other sources. So what does the GISS put in a cell that used to have actual data readings? Well, it is using a smoothing technique that allows it to use any temperature reading taken within 750 miles of the location the empty cell represents. For instance, rather than use a temperature reading from a mountaintop in Bolivia, the GISS can substitute a reading from the coast of Peru or from a steamy Brazilian jungle. Does no one in government see how a warming bias might, therefore, be baked into the global record? Accurate?

    [DB] "Accurate?"

    Nope.  Not in the least.  The various datasets (not just GISS) have been checked & rechecked, both internally and independently.  Even amateur "scientists" have replicated the global rise in temperatures using as little as 10% of the station data because there is a global warming signal in the data.

    You are repeating memes long ago proven false.  Care to share where you heard this and why you bring it up here (meaning SkS; this is definitely an appropriate thread)?

  14. 213, econ101lab, Your quote is from Climate Realists. The tone there is blatantly anti-science and conspiratorial, to the extent of being what I would label lunatic fringe. Other comments from that same page include: shortage of warmists waiting to pounce... What is troubling, however, is that some of the other candidates for the Republican nomination still accept the theory of man-made warming. Worse, they are apparently prepared to act on their beliefs if elected president. The planet is warming. Well, it was until 1998, when the warming trend abruptly ceased. In truth, it has been warming since 1850, when the last mini–Ice Age ended. The scientists at Great Britain’s Climatic Research Unit (CRU) admit to using statistical sleights of hand to change the temperature record, so as to show more warming.
    How can you take such utter nonsense seriously? How can you even bother to ask about such drivel?
  15. Actually it's from a Jim Lacy article in National Review online followed by: The graph below shows how damaging this smoothing is to the data record. Note the warming in the Arctic region. It seems like reason for concern, until one realizes that almost no actual data were used to create those dangerous-looking red zones. Instead, readings from almost 1,000 miles south of the polar regions were substituted for the missing data. How does such a substitution make sense unless one can convince oneself that it gets colder the closer one gets to the equator? The graph doesn't copy and paste. You can check out the whole piece here: If true, it's not drivel. If false, I like to check around and see what other people have to say. Your affronted attitude I find odd. Why should I trust you any more than Lacy? I don't know either one of you. I like to read from a broad spectrum of opinions and then check around. I bring it here as there seems to be an attempt to use real data. Of course the same could be said from sites on the other side of the question. That being said, I recently read about the CERN results here: and here: and here: Not being a scientist but an economist, I find the lack of certainty familiar (the "science" of economics is equally fraught with uncertainty) which makes me question the "settled science" position of one side of this arguement. I also find the proposed solutions by the AGW group absurd when looked at economically. In Michael Levitt's Superfreakonomics, there are proposed mitigation solutions (vs prevention) by a company called Intellectual Ventures headed by Nathan Myrvold (ex CTO of Microsoft) which would cause far less global economic disruption but achieve the same end result. SoSphaerica, pls keep you patronizing comments out of the thread.

    [DB] Do you mean this graphic:

    Junk Science

    You seem to frequent disinformation websites, where the focus is on conspiracy theories and not on the primary literature itself.

    No wonder you take the position you do.

  16. Re: 213 Can you point me to some of the data to which you refer regarding the data sets being checked? Not that I find what you say not credible, but I like to check things for myself. Thanks

    [DB] "Not that I find what you say not credible, but I like to check things for myself."

    Then you would be the first skeptic to actually follow through and do the hard work.  However, I suggest you start here, with additional resources available here and here.

    Please be sure to report back your results to us.

  17. Any comment on the CERN results? Are you seriously saying you support the "science is settled" position? If so, this site just lost all credibility with me if you leave no room for new scientific evidence or serious scientific inquiry. Sorry to take up your time.

    [DB] As someone new to SkS, you probably don't know how to best take advantage of all the resources this site has to offer.

    There is an immense amount of reference material discussed here and it can be a bit difficult at first to find an answer to your questions.  That's why we recommend that Newcomers, Start Here and then learn The Big Picture.

    I also recommend watching this video on why CO2 is the biggest climate control knob in Earth's history.

    Further general questions can usually be be answered by first using the Search function in the upper left of every Skeptical Science page to see if there is already a post on it (odds are, there is).  If you still have questions, use the Search function located in the upper left of every page here at Skeptical Science and post your question on the most pertinent thread.

    Remember to frame your questions in compliance with the Comments Policy and lastly, to use the Preview function below the comment box to ensure that any html tags you're using work properly.

    Participants who take the time to ensure a less incendiary tone will also find a great deal of positive and contributory dialogue with other, more knowledgeable participants here (some of whom are actual climate scientists).

  18. econ101lab @217 There is an entire post on the CERN results. No one is ignoring. You're just not looking hard enough. You could also read previous posts in this very thread touching on the very issues you mention in other posts. If you are just going to (re)post insinuation of fraud without basis, I don't see how you will add anything here.
  19. econ101lab - Welcome to SkS! Regarding CERN, I would suggest taking a look at: * ConCERN Trolling on Cosmic Rays, Clouds, and Climate Change * The CERN/CLOUD results are surprisingly interesting… (RealClimate) Now, on Arctic temperatures: * DMI and GISS Arctic Temperatures: Hide the Increase? Local temperatures vary a lot. However, the temperature anomaly, the change in temperature over time, season, climate changes, etc., that anomaly does not vary much over fairly large distances. Please look at some of the information on how these averages are done - on this site, that can be found at: * Of Averages and Anomalies - Part 1A. A Primer on how to measure surface temperature change * Part 1B. * Of Averages & Anomalies - Part 2A. Why Surface Temperature records are more robust than we think * Part 2B There's a lot of (dis)information out there, and it all sounds plausible at first glance. I would strongly encourage taking a look at how these temperatures are arrived at, and seeing why what gets posted on these 'skeptical' blogs is incorrect.
  20. Thank you KR!
  21. econ101lab, you stated you like to look at a variety of sources and check. That would be the right attitude. However, from what you wrote so far, I see little variety in the type of sources you look at and you are asking others to check for you. How come? In one of your posts, you say "if true." That suggests you have not actually looked into whether or not it is. As for the CERN results, one would be hard pressed to point exactly what words or numbers from Kirkby et al can be used to support the flashy headlines that you deemed appropriate to reproduce here. Others have supplied the links you need to check into that but, once again, I am surprised that you had not already found these on your own. The kind of skeptical attitude you claim would have allowed you to find these sources in only a few minutes of search engine use.
  22. econ101lab @215, your source appears to suggest that GISSTEMP temperatures are arrived at by simply cutting and pasting some other temperature from within a 1200 km radius. That is simply false. Rather, all stations within a 1200 km radius (over land) are given a weighting depending on their distance from center of the cell. The weighting is (1200 - distance in km from the center of the cell)/1200. All stations within range are then used to give a weighted average for the cell. The procedure is explained in detail in Averages and Anomalies part 1B. Very importantly, the HadCRUT is calculated by taking a simple mean of all stations within a cell, with no extrapolation. This is important because HadCRUT and GissTemp show effectively the same trend if you exclude polar regions, ie, the regions HadCRUT does not cover due to lack of surface stations. That shows the GissTemp procedure does not introduce a spurious trend. The comparison between GistTemp and DMI in the Arctic shows their extrapolation does not introduce a spurious trend in the Arctic either. Beyond that I heartily recommend you read the links provided by DB (inline comment @216) and KR @219. You should also add Ned's article on Assessing global surface temperature reconstructions to your reading. Finally, climate science is a diverse beast. Some parts of it are as well established as any other scientific theory, while other parts are relatively tenuous. Very little of it is as tenuous as even the best established theorems of macro-economics, and certainly the recent temperature record is not open to serious dispute. Is it settled science? Well researchers in the field will always try to improve their methods and eliminate assumptions that may have led them astray. But the results are sufficiently well established that people outside that narrow field can take the current results as being settled for the purposes of any further research they need to do.
  23. Tom, I will read your recommendation re: Ned's article. I fully accept your observation of the tenuous nature of macro economics as accurate due to the long time spans needed for observation and the virtually infinite and unobservable micro variables which can cumulatively affect the macro picture. This is why I have a tough time getting my arms around the "settled science" position. I'm not trying to be difficult but when two thirds of the planet isn't observed (either water temp or air temp over water) and one of the most significant variables isn't even modeled or clearly understood (clouds and cloud formation), the certainty smacks of intellectual hubris. As a non-climatologist, are there other untracked or unobservable variables of which I am unaware? Again, not trying to be a butt here. While I think Keynes and Galbraith were wrong based on the observable record and Friedman on the money, others dispute that looking at the exact same historical record (of course perhaps taking different micro impacts into account). OK, I've begun doing the reading suggested by KR (thank you again KR). I used the search function, unsuccessfully, to try and find previous posts for a few questions I have. My questions are regarding temperature records and how they're calculated. I ask the questions because I do not understand so please take them in that vein. First, wouldn't the cumulative error in a cell or block that is extrapolated vs observed, quickly make the data from that cell meaningless and affect the long term results more the longer it was used? Particularly if it was in close proximity to the central station and hence had a greater weighting? Second, Mr. Tamblyn does an excellent job laying this out for a non-climatologist. I understand the teleconnection concept and it makes sense as long as the station extrapolations take place from similar altitudes. I can think of numerous locations where I have been personally, where locations 50-60 miles apart might vary 50-60 degrees F. Palm Springs vs Big Bear Lake in California during the winter is an excellent example. I have played golf in the morning in 80 degrees in PS and then gone to the top of the tram where there's snow on the ground and the temp is in the 20's. If Big Bear were to be extrapolated from either LA or Palm Springs (both about 60 miles away) they would have significant weight due to proximity but no relevance. And is his contention that the Andes and coastal Peru have the same weather systems passing over accurate? The Andes are much higher than the San Gabriel Mtn's and the SGM's actually stop weather from the coast from moving inland. Meaning that one location (LA) has totally different weather from one 90 miles away (PS) precisely due to a geographical feature. Western and eastern Colorado create a similar situation. As do the Ngorongoro Crater and the Serengeti (went both places this summer, put it on your bucket list!) I looked at the gridded map and can see numerous places globally where this could logically happen. I see how it can be adjusted for if there are only occasional lapses in observed temp, but how is it adjusted when there is no station? Satellite? Thank you. Back to my homework.
  24. Philippe, you question my sources. What do you think I am doing here? Rather than snarky comments about my motives, I appreciate the willingness of KR, Tom, and DB to show me how the site works and give me a start on how to find information. Geez, lighten up.
    Response: You'll find less "snarkiness" in responses to you if you refrain from writing so stridently and confidently before you have read up on the rudiments. Folks here have a hair trigger for such behavior because it happens so often. Your failure to understand the really, really fundamental fact that temperature anomalies are used, is exactly such a case.
  25. econ101ab @223, it is very late here, and I am very tired, so I will only respond to your second point tonight. Essentially, you are ignoring the fact that the temperature calculations are for temperature anomalies rather than for absolute temperatures. An extrapolation of absolute temperatures would be absurd for exactly the reasons you give. The temperature anomaly, essentially the absolute temperature minus the mean temperature over some period, will not be so affected. Specifically, if it is an unusually warm day at Palm Springs, it will probably be an unusually warm day at Big Bear Lake as well. The difference in their anomalies on any day will be small even though the difference in their absolute temperature on every day is large. This is explained in greater detail in On Averages and Anomalies Part 1. (Link give by KR in 219 above.)
  26. @ econ101lab Aside from using the Search function, there are several ways to get the most out of SkS: 1. By Argument # 2. By Popularity 3. By Taxonomy (my favorite) 4. By Chronological Posting These will find most of the 4,000+ blog posts here at SkS. As always, if/when questions arise on a particular thread, feel free to post those questions there (or on another more appropriate thread) and someone will get back to you. Regular participants here follow the Recent Comments thread, so any new comments posted will be noticed regardless of the thread that they are posted on. Happy Hunting!
  27. 224, econ101lab, You are advised to eliminate the following sorts of offensive falsehoods and snarky implications from future comments if you wish to learn and be guided, rather than to make a splash and warp other people into matching your own flavor of I-read-it-somewhere-and-I-believe-it-until-you-prove-otherwise:
    • I have a tough time getting my arms around the "settled science" position
    • when two thirds of the planet isn't observed
    • one of the most significant variables isn't even modeled or clearly understood (clouds and cloud formation)
    • smacks of intellectual hubris
    • are there other untracked or unobservable variables of which I am unaware?
    All of this was in your opening paragraph, before you asked perfectly valid questions, but also laced them with a litany of misinformation and misunderstandings about temperature measurements on which your own confusion was based. In the future, if you don't know, simply ask. Don't broadcast an offensive and ignorant position, and use your comment to litter the world with even more misinformation of your own. If your goal is to learn, then learn. If your goal is to pontificate on things you don't understand, then expect a fair amount of blow-back here.
  28. econ101lab - just a further comment on the anomaly method - this isn't just an hypothesised method. The strong spatial correlation of anomalies has been checked by studies (see KR articles for references).
  29. I'm sure there is a response to this somewhere, but i can't find it: Any help would be much appreciated
  30. The Advanced verwion of this rebuttal contains seven graphics of selected temperature anomalies plotted against time. Nowhere in this article can I find a definition of what a temperature anomaly is. Can someone please explain what I am looking at in each graphic?

    [DB] Per NOAA:

    What is a temperature anomaly?

    The term “temperature anomaly” means a departure from a reference value or long-term average. A positive anomaly indicates that the observed temperature was warmer than the reference value, while a negative anomaly indicates that the observed temperature was cooler than the reference value.

    What can the mean global temperature anomaly be used for?

    This product is a global-scale climate diagnostic tool and provides a big picture overview of average global temperatures compared to a reference value.

    Why use temperature anomalies (departure from average) and not absolute temperature measurements?

    Absolute estimates of global average surface temperature are difficult to compile for several reasons. Some regions have few temperature measurement stations (e.g., the Sahara Desert) and interpolation must be made over large, data-sparse regions. In mountainous areas, most observations come from the inhabited valleys, so the effect of elevation on a region’s average temperature must be considered as well. For example, a summer month over an area may be cooler than average, both at a mountain top and in a nearby valley, but the absolute temperatures will be quite different at the two locations. The use of anomalies in this case will show that temperatures for both locations were below average.

    Using reference values computed on smaller [more local] scales over the same time period establishes a baseline from which anomalies are calculated. This effectively normalizes the data so they can be compared and combined to more accurately represent temperature patterns with respect to what is normal for different places within a region.

    For these reasons, large-area summaries incorporate anomalies, not the temperature itself. Anomalies more accurately describe climate variability over larger areas than absolute temperatures do, and they give a frame of reference that allows more meaningful comparisons between locations and more accurate calculations of temperature trends.

  31. DB: Thank you for providing the information about "temperature anomaly. Can you tell me what reference value or long-term average was used to compute the temeparture anomalies for each of the eight figures in the Advanced version of this rebuttal?

    [DB] Typically, if no baseline is specified it is understood that the baseline used is 1951-1980.  However, since the above work goes back to original data any baseline theoretically could have been used (but it's safe to assume that they share a common baseline).  JC would be the one to ask for a definitive answer.

  32. DB: Our exchanges suggests to me that the Advanced rebuttal needs to be updated to better explain the issues we have addressed in #230 and #231. I'm getting hammered on a comment thread to an article posted on NPR who insists that Figure 7 shows a definite cooling trend over the last 9-10 years.
  33. A 9-10 year period is statistically insignificant (ask him to show the significance testing he's done on those 9-10 years). Thus there is no deviation or break in the overall trend. 15 of the 17 warmest years in the modern record have occurred in the past 17 years (which cover the warmest decade in the instrumental record).
  34. Daniel Bailey: As soon as I state that a 9-10 year period is stastically insignificant, he will ask me why it isn't.
  35. Santer et al 2011 (discussed here) show that 10 year flat periods can occur in overall warming periods caused by human influence and that at least 17 years is needed to establish a human influence on tropospheric temps. It takes a world-class time series analyst to properly control for exogenous factors to establish significance in time series of less than 17 years, as Tamino does here. If your counterpart doesn't understand significance testing then ask him how he can believe anything at all that anyone tells him, one way or another, about climate science. Or the stock market.
  36. @John Cook: The Advanced rebuttal needs a good rewrite!
  37. Any word on how much HadCRU4 will rectify this discrepancy?
  38. Hi, I can think of another approach (possibly) to combating the folks claiming its not getting hotter here on the earth, and to do this for an audience. Has the advantage that you don't have to mess with a bunch of different graphs, contrasting Artic to Antarctic, etc. 1. Actually demo the water going into a funnel with a hole and coming out a stopcock which can be closed slightly (analogous to more CO2). As Hanson point out, and is evident from Toricelli's theorem, the water will slowly rise to a new level until the input flow equals the output flow.I am about to make one of these things. 2. Then I say " Maybe thousands of smart people all over the globe are measuring the energy input coming into the earth ,and also the energy leaving. And guess what? The power coming in exceeds the power going out. Its like the funnel with a larger rate of flow coming in than is going out the hole" 3. Therefore, the temperature of the earth is rising. Q.E.D. Whaddya think?
  39. ciriousd, The difficulty is that it is no easier to measure the total radiation differential (energy in, energy leaving, over the entire surface of the earth) than it is to directly measure a "global mean temperature." Beyond this, on any one day the imbalance may be in one direction, then another. In particular, counter-intuitively, while a La Niña appears to cool the planet (global temperatures drop) it is in fact warming the planet (because the total energy level of the system has not actually changed, but the atmosphere is radiating less to space, and therefore warming more quickly). Things are further complicated by the need to translate the energy imbalance (measured in W/m2) to some sort of rate of temperature increase. That's pretty much impossible, because how the energy sorts through the system (air, ocean, ice) is just too complicated. So, I'm afraid your simple 3 step approach does no better than simply proving that the earth is warming. It still comes down to a complex interpretation of complex observations of values that vary wildly over both time and three-dimensional space, and yet must be averaged together to get a coherent set of numbers (and trend).
  40.  The various datasets (not just GISS) have been checked & rechecked, both internally and independently.  Even amateur "scientists" have replicated the global rise in temperatures using as little as 10% of the station data because there is a global warming signal in the data.

    If the data is/was so accurate, why does Hansen keep changing it?  And why are ALL changes in the direction that support his belief?  You would think that at least some "mistakes" were made in the other direction, no?  How much cooler are the 30's going to get?

  41. Kevin,

    Do you have no clue how this works?

    First, "Hansen" doesn't personally go changing things. This habit of deniers of first personalizing the science (it's "Al Gore's" or it's "Hansen's") and then villifying that person is just foolishness.

    That said, the data is continually improved because it always helps to make it better... except that the validity and accuracy of the data is already good enough for our purposes.

    As far as changes in a direction that "support his belief," scientists don't have beliefs, they have conclusions.  It's deniers whose positions are founded entirely on beliefs.

    How much cooler are the 30s going to get?  LOL.  2013 is going to be a "wake up and smell the thermometer" year for you and your ilk.

  42. Kevin:

    The point being made is that, without regard for the accuracy or precision of the instrumental record, you can still replicate the 20th-century global warming signal using only a subset of the data. That is how powerful global warming is.

    It would be nice if you could provide a reference to any change to 1930s instrumental data. But based on this thread and the "It's the Sun" thread I don't think we're going to see it.

    I should also like to echo Sphaerica's irritation at your peculiar reference to Hansen. As Sphaerica notes, it is done in a style all too remniscent of behaviour characteristic of deniers & cranks.

    I should also like to add some irritation at what appears to be another behaviour in the same style: popping on multiple threads with small, largely content-free, smear-like or "gotcha"-style comments. We're at two now. Will there be more?



    It would be nice if you could provide a reference to any change to 1930s instrumental data. But based on this thread and the "It's the Sun" thread I don't think we're going to see it.

    Actually, this is the "accuracy in the data" thread, not the Sun thread, so it is appropriate to discuss this.


    This is from WUWT,

    Just because it is from there don't discount it out of hand.  It shows temp change since 2008 made to the record, it was originally from Climate4You.


    Hopefully the chart comes through, but anyway, it shows significant adjustments, so that should satisfy your need for showing what I was talking about.


    As far as changes in a direction that "support his belief," scientists don't have beliefs, they have conclusions.  It's deniers whose positions are founded entirely on beliefs.

    I disagree.  When it comes to Hansen, who has publically stated his beliefs, and his position, and done so in a manor that can not be confused with stating scientific knowledge or facts.  Otherwise, I would agree with you.

    See my other posts about appology regarding my smear/gothca impression - not intended.



  44. Update: I accidentally took the 2008 figures from the land only dataset rather than the LOTI. The change in dataset completely undermines my earlier conclusions, and I apologize for the error. The actual adjustments differ in detail from those in the Figure displayed by Kevin, but not by a large amount. The table and links are now for the correct figures, but the comments should be ignored. Kevin @243, merely mentioning that the figure is from WUWT does not help us determine its accuracy. You need to list the source data. When I check the source data that I can access for 22nd July, 2008 and for 8th Feb, 2013 (today), I note that the annual temperatures for the twenty first century are as follows: ______2008___Current___Alteration 2001 48 52 0.04 2002 56 60 0.04 2003 55 59 0.04 2004 48 52 0.04 2005 62 65 0.03 2006 54 59 0.05 2007 56 62 0.06 Now, every one of those adjustments makes the first seven years of the twenty first century cooler than they were reported to be in 2008, yet your table shows every one of those years as have been adjusted to make them warmer. For convenience, I have only checked the years above, but at the moment every claimed adjustment on the graph does not even get the direction of the adjustment right. I see no reason, then, to trust it.

    I also note that, if there is in fact some version of Gistemp which does adjust those years as per the chart, then there the adjustments between that chart and 2013 at most merely restore the values to those of the July 2008 version, and in some years still represent an overall net cooling adjustment.
  45. Kevin, assuming that the methodology of the graph is honest, what makes you think that the adjustments are dishonest?  If they were exactly reversed, would you still be complaining?  

    And what is the method for determining statistical significance in this case?  And is that the anomaly?  Or is that the absolute temp?  

  46. Kevin, to put that diagram into perspective, if you look at GISS LOTI, there has been abou 0.9 degrees of warming since 1911 (the lowest point on the WUWT plot), so the difference between GISS products accounts for less than 10% of the observed warming.  There is also the point that the adjustements made since 2008 are likely to have been made for good reasons.  If you want to know why "Hansen" (GISS != Hansen) keeps changing the temperature record, then I suggest reading the technical reports and papers might be a good start.

  47. Kevin:

    Thank you for returning to follow up. It has been my experience that commenters who post on multiple threads in short order with what appear to be leading questions or comments are engaging in "drive-by" commenting. One rarely sees them again (except, perhaps, for further drive-bys some months in the future). Since you have returned, I apologize for my viscerally hostile reaction.

    Further to the graph, posted on WUWT, that you have shared here, I guess my follow-up questions are:

    1. To what NASA GISS product are the shown adjustments applicable? NASA GISS model or the temperature dataset?
    2. What makes the adjustments illegitimate? Do WUWT or Climate4You provide any references to the literature suggesting NASA GISS has committed any serious methodological errors in making the adjustments?

    That adjustments have been made does not make them prima facie suspicious. Organizations and people re-evaluate past data using improved methods and make revisions as required (one example might be casualty figures from past conflicts, which are subject to occasional re-assessment - e.g. casualties suffered by the polities of the former Soviet Union during the Second World War). As far as I can see this is normally unremarkable behaviour.

    With regards to Hansen's beliefs vs his conclusions, the question is, what evidence is there that any of Hansen's personal convictions (such as those described in, say, his recent book) are inappropriately reflected in his published work? Certainly such a thing is possible, but it doesn't follow that it is occurring without some sort of substantiation.

  48. Kevin, climate4you is run by Ole Humlum, who has written a number of deeply flawed papers on climate science, so pointing out that the plot originates from climate4you rather than WUWT does not make it any more authoritative.  This doesn't mean that the plot is incorrect, but it is good cause to be skeptical.

  49. To reiterate what others have said, without details of the source data we can only speculate. However the graph above does look rather different from this one:

    Source: here. Links to the source datasets are provided in that post.
  50. I plotted the difference between the current GISTEMP, and the archived 2008 data (via WUWT); while the graph is not exactly the same as the one posted by Kevin, they are close enough that I think I have the right data set ( the difference is possibly due to me using Jan-Dec as the year rather than Dec-Nov, but I haven't bothered to check)

    Blue is the current GISTEMP up to 2007, with green being the difference between current GISTEMP and GISTEMP in April 2008. Point is overall adjustment is still small.

    The green curve can largely be explain through two "big" adjustments made since the RC post linked to in post 249. First is the change from GHCN v3.1.0 to GHCN v3.2.0 for the surface stations in Sep 2012 (documented here), and the switch form HADISST+Reynolds OI ocean data to ERSST (just last month. Confirmation from GISS).

    Green is the difference between current GISTEMP and GISTEMP in April 2008. Blue is the shift due to change in Ocean data. Red is shift due to land data change.

    Note that the overall trend changes are

    Overall change in trend:0.057 oC/century
    GHCN v3.1 to v3.20.040 oC/century
    Change in ocean data0.0089 oC/century


    Now Kevin,

    (1) Most of the adjustment is due to switching from GHCN from v3.1 to v3.2. This is done by NOAA and is due to better algorithm for detecting inhomogeneities in temperature record(see here). Note that this an automated program, so unless you have a valid criticism on the algorithm, you can't simply attribute this adjustment as a reseracher's bias.

    If the better algorithm says the temperature needs to be adjusted downwards and it is ignored, you can be sure folks over at WUWT will be all over it.

    (2) The change that Dr. Hansen can actually decide on, is the switch of ocean dataset. First off, prior to 2013 the ocean data actually consists of two chucks, HADISST prior to 1980, and Reynold OI dataset from 1980, so it is possible that there are inconsistencies; on the other hand ERSST is a complete dataset.

    If the decision to change dataset is to simply inflate the warming, they could've done it back in 2010. Hansen et al (2010) wrote:

    Until there is a demonstrably superior ocean data set, we will retain HadISST1 plus OISST (concatenated as in our analyses for the past several years) in our standard analysis

    Thus they have been evaluating the relative merits of the two datasets for at least two years. Furthermore, in the same paper it was revealed that if they went with a third dataset (HADSSTv2) the warming is even stronger. So the question is, if Hansen's science is based on his personal opinion rather than careful analysis, why did he wait two years? Why didn't he choose the dataset that results in the most warming?

    (3) Your claim that "ALL changes in the direction that support his belief?" is demonstrably false. In Jan 2010, an adjustment resulted in a decrease in global trend of 0.005oC/century 

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