How subjective is the process of measuring global surface air temperature?

Question

Most people agree that the Earth has been warming since 1850 or so since the end of the Little Ice Age. But the actual raw temperature data has to undergo a series of adjustments for a variety of reasons like stations being relocated, local vegetation changing (especially urbanization), etc.

So for this question, I'll add some links and information to draw upon. Here is a Q&A site for GISS who produces one of the prominent global temperature data sets (i.e. James Hansen):

"To measure SAT (Surface Air Temperature) we have to agree on what it is and, as far as I know, no such standard has been suggested or generally adopted."

"The reported temperature is truly meaningful only to a person who happens to visit the weather station at the precise moment when the reported temperature is measured, in other words, to nobody."

"If SATs cannot be measured, how are SAT maps created ? This can only be done with the help of computer models..."
http://data.giss.nasa.gov/gistemp/abs_temp.html

And this is from the NOAA regarding the US Historical Climate Network data sets:

"The period of record varies for each station but generally includes the period 1900-1995. The stations were chosen using a number of criteria including length of period of record, percent missing data, number of station moves and other station changes that may affect the data homogeneity, and spatial coverage."
http://www.ncdc.noaa.gov/oa/climate/research/ushcn/ushcn.html

It appears that analyzing raw surface temperature data is not easy and thus expert opinion is needed and agreement must be reached on several issues.

Do most people realize that when they are presented with a visual graph of temperature data that there has been a lot judgment involved? Just how much subjectivity is used for this analysis?

As a final note, here is the combined USHCN adjustment graph to the raw data: http://www.ncdc.noaa.gov/img/climate/research/ushcn/ts.ushcn_anom25_diffs_urb-raw_pg.gif

Answer 1

As usual, Mike pretends to be interested in science, by pretending here to fairly present excerpts from NASA and NDCC websites, but in fact a little simple googling turns up these cherry-picked-for-deception quotes all over the anti-science blogosphere on denier trickster sites such as SteveGoddard.com.

https://answersrip.com/question/index?qid=20110309123406AA1ne91

http://www.desmogblog.com/directory/vocabulary/3377



The key trick being used here is to cloak the reality that these various techniques apply to procedures for estimating the temperature NOT (a) at one particular location (if that were as difficult as these quotes suggest then your basic evening news weather forecasts would be unreliable and whole weather forecasting business part of Al Gore's Mighty Time Machine Conspiracy), but (b) the AVERAGE TEMPERATURE OF THE WHOLE WORLD. Obviously (b) is a more complicated project.

http://en.wikipedia.org/wiki/Temperature_measurement#Surface_air_temperature



You could make the same kind of crap trickster arguments for denying the validity of global measures of GNP, inflation rates, arable land acreage, human consumption of meat, dental hygiene or drug use. But all of these are in fact genuinely meaningful and more or less reasonably estimable matters. Why is such deceptive garbage much more prevalent when it comes to climate science? This explains part of the reason: http://www.newsweek.com/2007/08/13/the-truth-about-denial.html

Answer 2

Again Ottawa Mike, why don't you first establish that the adjustment of data is actually fraudulent and/or unscientific?



This is another typical denier tactic: when you do not have a scientific leg to stand on, question the data/the process/the equipment/the scientists anyway to make it appear there is legitimate reason to question them.



Edit @ O Mike:



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They do when they imply that there is something wrong with the data. This is your second 'question' here in which you implicitly imply that there is something wrong with the data which climate scientists use. That is the same tactic you always use.



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Exactly, and that is your WHOLE point of bringing it up. It's yet another subtile manner in which you can question climate science without actually having to find a specific fault in the scientific data. It works brilliantly time and time again judging by the responses here from your fellow deniers. What you are doing is not honest.



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Care to back that up? With credible info? Not infowars, not WUWT, not opinion pieces?



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You 'question the method' because you do not like the results but you do not have a shred of evidence that anything wrong or fraudulent has happened. How scientific! It's the 'Urban Heat Island Effect' tactic all over again.



Why don't you point to some credible papers discussing this very item, papers which to date have not been refuted by multiple other scientists? I think I know why you don't; there are no such papers. All there are is opinions, primarily from those skeptic scientists whose claims have been debunked scientifically and now act unscientifically by writing op-eds and opinion pieces for denier blogs.



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Your problem is that you continously reject the answers which science gives you because you don't like them.

Answer 3

I would say you have asked the wrong question (reminds me of that hologram in "I, Robot").



I would argue that the process of measuring SAT is not very subjective at all, instead the question is how "precise" is the process of measuring SAT in delineating global SAT? (The NASA site pretty much follows this line of argument too).



Statistical analysis can overcome many of the inherent "errors" associated with human observations (the possible subjectivity in the process), however the analysis can not improve the precision unless the sample size is increased (whether number of samples, frequency, distribution etc.)



The actual statistical analysis is based in objective methods. Generally a model's statistical analysis, equations and processes will be documented and open to critique. Any subjectivity in such models would result in the models being disregarded as bias and "unfit". This is why snippets of data are generally not used for trends (instead longer time periods are) ... as cherry picking the data is subjective and leads to bias.



Also it is important to remember that the accuracy of weather data is generally analysed. That is the actual numbers collected aren't crunched but the anomalies (or variation from the "normal" for the stations). This reduces the error in statistics, as it improves accuracy by comparing all measures from each station instead of between stations. Therefore can use the temperature anomalie at each station as a comparison between stations instead of the raw data (which would have more variation, human errors). Also gives a standard variable between stations.



All this is rooted in statistics (not climate change science). Maths and statistics are far from subjective (well at least in my experience).



Sure statistics can tell you what you want them too ... but that is where science determines the validity of the statistics.

Answer 4

I live within walking distance of the Pacific Ocean, and I have lived here when the alarmists/leftists were proclaiming global cooling. Over 30 years ago they started chanting global warming and predicted that where I live would have a serious rise in ocean levels, flooding lowlands, that would happen within twenty year or less. That was 25 years ago and I'm still waiting. Nothing has changed, not the ocean level, not the water temperature. The state climatologist, George Taylor, exposed the scam, and he is a real scientist, not a politician. The state governor read Taylor's report, and fired him, or tried to. Taylor wasn't politically correct. Also, I studied Earth Science in college as a minor. Also, I'm not new to science; I've spent my live working in Science and Technology. All my friends are scientists or technologists. So, don't repeat Al Gore's lies to me. This climate change hoax runs along leftist political lines, and it is fed by liars and morons. Believe it!

Answer 5

I find it surprising that Jim Z unleashes an attack on statistics, when it's the same likelihood theory that allows Economists to make claims that certain regulations will "destroy the economy." But I'm sure those are all of the honest, and well calculate statistics right?



As mentioned in a previous but similar question of yours, global temperature is a latent variable, one that cannot be directly measured, only estimated using what information is available.



We cannot place a high resolution thermometer on every square meter of the planet, providing appropriate resolution, but we can use math and knowledge of the effects of topography and regional climate to interpolate between measurement points and develop a mesh estimate.



Because this process is mathematically complex a model is developed to execute these calculations in a usable framework.



As far as the adjustments go, I am not familiar with the methods or how much subjectivity is involved. Quite possibly the adjustments are due to recent advancement in interpolation methods resulting in the previous version being faulty.



I can see, from a "skeptics" standpoint, how continuous upward adjustments seems to be obvious manipulation to promote a cause, but active politics don't supply the available capital to take such actions.

Answer 6

I would say for earlier time periods it's entirely subjective. There was minimal global temperature coverage in the late 1800's and early 1900's (the arctic is still one big guess) and thus temps are extrapolated across thousands of miles. To say you know what the average global temp was with any accuracy is laughable to anyone but alarmists.



It will be interesting to see which way GISS temps go in the next few decades. I firmly believe that Hansen et al have pretty much run out of excuses to adjust temps higher without raising the eyebrows of even the most die hard alarmists (although judging from the "Science should not be questioned, science should be believed" answers from alarmists on YA I could be wrong). The last upwards adjustment made 2010 as the hottest year on record. Hopefully that's as hot as it will get.

Answer 7

Mike your questions are merely rants, not questions at all. Then you use contrary responses as license to rant more.



Last I read temps were taken from over 6,000 reporting stations worldwide to determine an average global temp. They look at the thermometer, record the temp and pass the info along. It isn't magic, nor is it really a debatable issue. You just like sensationalizing things for the furthering of your beliefs. Seriously how difficult is it for you to fathom this.

Answer 8

That the near-surface temperature of the earth’s atmosphere has been increasing over the last several decades is almost certain; however, whether the warming is attributable to increasing levels of greenhouse gas concentrations is still questionable (Santer et al. 1996a). The issue of attributability is commonly addressed by looking for distinctive features in the pattern of the observed warming that are predicted by theoretical models of the climate system. Recent pattern-based studies have examined surface-air temperature data from the past century (Hegerl et al. 1996a,b; Hegerl et al. 1997) and radiosonde records from the past 50 years (Santer et al.

1995; Santer et al. 1996b; Tett et al. 1996). The results of the pattern-based signal detection studies

to date point toward a human influence on present trends in the earth’s climate (Santer et al. 1996a). This conclusion could be made stronger, though, by future satellitebased observations of the atmospheric state for two reasons. First, unbiased observations containing information Corresponding author address: Dr. Stephen Leroy, Earth and Space Sciences Division, Jet Propulsion Laboratory, Mail Stop 183-335,California Institute of Technology, 4800 Oak Grove Drive, Pasadena,CA 91109-8099. the vertical structure of the atmosphere can alleviate detection studies’ dependence on model-determined variability of the climate system. Indeed, ocean circulation variability is known to have associated timescales on the

order of decades to centuries, and the climate record still contains unexplained variances on the decadal scale (Santer et al. 1996a). Even though recent studies indicate that

sea surface temperature anomalies are not enough to explain surface-air temperature increases (Folland et al. 1998), the sparsity of data on the ocean still makes it a large unknown in the climate system. A detection study using data with vertical information content can circumvent the difficulty of oceanic variability because it offers the possibility of differentiating such variability from

trends caused by increased greenhouse gas forcing. Second, it is certainly desirable to obtain fully global coverage of the atmosphere to understand the condition and trends of the climate system. Most detection studies to date have been done with land-based in situ data such as meteorological stations and/or radiosonde soundings. Radiosonde soundings, for instance, may remain somewhat influenced by systematic errors (cf. Gaffen 1994), whereas future satellite missions may not suffer from calibration error at all (Goody et al. 1998)

Answer 9

You said it yourself, the raw data cannot be interpreted except by an expert analyst. Computer models, expert analysis, refined data, is not subjectivity. It is the science of statistics combined with the science of meteorology.



Just because information needs to be analyzed by computer model to get to the conclusion that the earth is in fact, warming, and that warming is likely cause by humanity's industrial revolution and the massive burning of fossil fuels, doesn't make that a subjective opinion. Its a scientific opinion. A theory with significant supporting documentation.



Here's another thought: If you don't want to accept this theory as true, what's the consequence of you and the majority of our world believing that global warming is a myth, and being wrong? Once temperatures get too high, we will have massive crop failures, and food shortage. AKA Famine. With shortages of food, people will fight over resources. AKA War. War will bring Death, Death will breed diseases, AKA Pestilence. Whoa, the four horsemen of the apocolypse! Will this happen? I honestly don't know. Not in our lifetimes, anyway. But my children? My grandchildren? We do not own this planet, we borrow it from our descendants.



Or, we could accept the Global Warming Theory as sound, and make every effort to reduce our carbon footprint and environmental impact. If the theory is wrong, we could waste billions of dollars on the effort to reduce our impact on the world. In the end, the Earth still has a viable environment, and no massive crop failures.



So, I stick on the side that says Global Warming is happening (proven by the data) and that humans are the cause (still theory, but look at how much impact we've had on the environment.) Concern about the Earth is about keeping the Earth a viable habitat for HUMANS, so that we have some place to live.



@JimZ, I fail to see how your anecdotal quotes as to the incorrect uses of statistics equates the science of statistics to being falacious. I use statistics everyday. I don't use them to lie to people, just to analyze data. That's something an engineer does. Coming up with quotes from a bunch of people poo-pooing it doesn't mean its anything less than mathematics, with one correct answer for a set of data.



@JimZ Re: "...at least I am honest about them. I can manipulate the statistics to say exactly what I want. For example, if I want to close a site, I can show a statistical downward trend. If it isn't ready, I can select a different set of data with a different time interval. I can look at water, soil, or vapor results. Playing with statistics is easy. " That's what I mean when I say there's one right answer. You're using statistics to lie. In other words, cherry picking the data to support your conclusion. The conclusion drawn from a data trend is only as reliable as the person creating the chart or analyzing the data. That's kind of the point of James Hansen's comment that was taken a bit out of context in this question.

Answer 10

Morgan said

It is the science of statistics combined with the science of meteorology.



Is he serious?

"There are three kinds of lies: lies, damned lies, and statistics."



Torture numbers, and they'll confess to anything. ~Gregg Easterbrook





98% of all statistics are made up. ~Author Unknown





Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital. ~Aaron Levenstein





Say you were standing with one foot in the oven and one foot in an ice bucket. According to the percentage people, you should be perfectly comfortable. ~Bobby Bragan, 1963





Statistics can be made to prove anything - even the truth. ~Author Unknown





Statistics are human beings with the tears wiped off. ~Paul Brodeur, Outrageous Misconduct





Facts are stubborn things, but statistics are more pliable. ~Author Unknown





Lottery: A tax on people who are bad at math. ~Author Unknown





He uses statistics as a drunken man uses lampposts - for support rather than for illumination. ~Andrew Lang



And if those didn't wear you out. http://www.quotegarden.com/statistics.html



I didn't directly answer your question but hopefully made my point. I do agree that it seems so non standardized for such an important measurement.





Note: You try to argue science with them. I must commend you for that but clearly they aren't interested.



David, that sort of nonsense is beneath you. I didn't attack statistics. I merely provided numerous examples of people that did. You would have to be a completly gullible or an alarmists not to understand the point of those quotes. It was Morgan that put his faith in statistics. I merely pointed out the problems with that sort of reasoning or lack there of.



Morgan, I use statistics everyday too except at least I am honest about them. I can manipulate the statistics to say exactly what I want. For example, if I want to close a site, I can show a statistical downward trend. If it isn't ready, I can select a different set of data with a different time interval. I can look at water, soil, or vapor results. Playing with statistics is easy. Why do alarmist pretend it is somehow science? I really feel like I am arguing with junior high schoolers. The sophistication and knowledge that I see from alrmists isn't impressive at all. In fact it just makes me think our schools have utterly failed.