Temperature averages of continuously reporting stations from the GISS dataset
Guest post by Michael Palmer, University of Waterloo, Canada
Abstract
The GISS dataset includes more than 600 stations within the U.S. that have been
in operation continuously throughout the 20th century. This brief report looks at
the average temperatures reported by those stations. The unadjusted data of both
rural and non-rural stations show a virtually flat trend across the century.
The Goddard Institute for Space Studies provides a surface temperature data set that
covers the entire globe, but for long periods of time contains mostly U.S. stations. For
each station, monthly temperature averages are tabulated, in both raw and adjusted
versions.
One problem with the calculation of long term averages from such data is the occurrence of discontinuities; most station records contain one or more gaps of one or more months. Such gaps could be due to anything from the clerk in charge being a quarter drunkard to instrument failure and replacement or relocation. At least in some examples, such discontinuities have given rise to “adjustments” that introduced spurious trends into the time series where none existed before.
1 Method: Calculation of yearly average temperatures
In this report, I used a very simple procedure to calculate yearly averages from raw
GISS monthly averages that deals with gaps without making any assumptions or adjustments.
Suppose we have 4 stations, A, B, C and D. Each station covers 4 time points, without
gaps:
In this case, we can obviously calculate the average temperatures as:
A more roundabout, but equivalent scheme for the calculation of T1 would be:
With a complete time series, this scheme offers no advantage over the first one. However, it can be applied quite naturally in the case of missing data points. Suppose now we have an incomplete data series, such as:
…where a dash denotes a missing data point. In this case, we can estimate the average temperatures as follows:
The upshot of this is that missing monthly Δtemperature values are simply dropped and replaced by the average (Δtemperature) from the other stations.
One advantage that may not be immediately obvious is that this scheme also removes
systematic errors due to change of instrument or instrument siting that may have occurred concomitantly with a data gap.
Suppose, for example, that data point B1 went missing because the instrument in station B broke down and was replaced, and that the calibration of the new instrument was offset by 1 degree relative to the old one. Since B2 is never compared to B0, this offset will not affect the calculation of the average temperature. Of course, spurious jumps not associated with gaps in the time series will not be eliminated.
In all following graphs, the temperature anomaly was calculated from unadjusted
GISS monthly averages according to the scheme just described. The code is written in
Python and is available upon request.
2 Temperature trends for all stations in GISS
The temperature trends for rural and non-rural US stations in GISS are shown in Figure
1.
This figure resembles other renderings of the same raw dataset. The most notable
feature in this graph is not in the temperature but in the station count. Both to the
left of 1900 and to the right of 2000 there is a steep drop in the number of available
stations. While this seems quite understandable before 1900, the even steeper drop
after 2000 seems peculiar.
If we simply lop off these two time periods, we obtain the trends shown in Figure
2.
The upward slope of the average temperature is reduced; this reduction is more
pronounced with non-rural stations, and the remaining difference between rural and
non-rural stations is negligible.
3 Continuously reporting stations
There are several examples of long-running temperature records that fail to show any
substantial long-term warming signal; examples are the Central England Temperature record and the one from Hohenpeissenberg, Bavaria. It therefore seemed of interest to look for long-running US stations in the GISS dataset. Here, I selected for stations that had continuously reported at least one monthly average value (but usually many more) for each year between 1900 and 2000. This criterion yielded 335 rural stations and 278 non-rural ones.
The temperature trends of these stations are shown in Figure 3.
While the sequence and the amplitudes of upward and downward peaks are closely similar to those seen in Figure 2, the trends for both rural and non-rural stations are virtually zero. Therefore, the average temperature anomaly reported by long-running stations in the GISS dataset does not show any evidence of long-term warming.
Figure 3 also shows the average monthly data point coverage, which is above 90%
for all but the first few years. The less than 10% of all raw data points that are missing
are unlikely to have a major impact on the calculated temperature trend.
4 Discussion
The number of US stations in the GISS dataset is high and reasonably stable during the 20th century. In the 21st century, the number of stations has dropped precipitously. In particular, rural stations have almost entirely been weeded out, to the point that the GISS dataset no longer seems to offer a valid basis for comparison of the present to the past. If we confine the calculation of average temperatures to the 20th century, there remains an upward trend of approximately 0.35 degrees.
Interestingly, this trend is virtually the same with rural and non-rural stations.
The slight upward temperature trend observed in the average temperature of all
stations disappears entirely if the input data is restricted to long-running stations only, that is those stations that have reported monthly averages for at least one month in every year from 1900 to 2000. This discrepancy remains to be explained.
While the long-running stations represent a minority of all stations, they would
seem most likely to have been looked after with consistent quality. The fact that their
average temperature trend runs lower than the overall average and shows no net warming in the 20th century should therefore not be dismissed out of hand.
Disclaimer
I am not a climate scientist and claim no expertise relevant to this subject other than
basic arithmetics. In case I have overlooked equivalent previous work, this is due to my ignorance of the field, is not deliberate and will be amended upon request.
Brian says:
“But once it’s clear the earth is warming (really it already is) you need to suggest a cause. Either it’s the human emissions of gasses that are known to have warming effects, or something else. The possible list of “something else” shrinks as temperatures keep going up. Claiming that it’s a coincidence is pretty hard to swallow.”
• • •
Brian, Prof Richard Lindzen explains:
The notion of a static, unchanging climate is foreign to the history of the earth or any other planet with a fluid envelope. The fact that the developed world went into hysterics over changes in global mean temperature anomaly of a few tenths of a degree will astound future generations. Such hysteria simply represents the scientific illiteracy of much of the public, the susceptibility of the public to the substitution of repetition for truth, and the exploitation of these weaknesses by politicians, environmental promoters, and, after 20 years of media drum beating, many others as well. Climate is always changing. We have had ice ages and warmer periods when alligators were found in Spitzbergen. Ice ages have occurred in a hundred thousand year cycle for the last 700 thousand years, and there have been previous periods that appear to have been warmer than the present despite CO2 levels being lower than they are now. More recently, we have had the medieval warm period and the little ice age. During the latter, alpine glaciers advanced to the chagrin of overrun villages. Since the beginning of the 19th Century these glaciers have been retreating. Frankly, we don’t fully understand either the advance or the retreat… For small changes in climate associated with tenths of a degree, there is no need for any external cause. The earth is never exactly in equilibrium. The motions of the massive oceans where heat is moved between deep layers and the surface provides variability on time scales from years to centuries. Recent work suggests that this variability is enough to account for all climate change since the 19th Century. [my emphasis]
Invoking “carbon” as a cause of natural climate variability is the basis for the entire climate alarmist industry. But the 40% increase in harmless, beneficial CO2 has not made an appreciable difference; the warming over the past century and a half has been from 288K to 288.8K, a minuscule rise. And there is zero testable evidence that it was caused by the rise in CO2.
@DirkH says:
October 24, 2011 at 10:27 am
“One of the longest running records in Europe is Berlin; nearly no trend over 300 years”
Berlin Dahlem is also one of the sites which has been removed from the GISS record last year
Brian, we don’t need to suggest a cause for the current warming because natural variability is the null hypothesis.
Before I could accept climate change as caused by anthropogenic CO2 emissions the following would have to apply :-
1. Temperatures would have to rise above those in the Medieval Warm Period, the Roman Warm Period, the Minoan Warm Period, most of the early Holocene, and several earlier interglacial periods. Otherwise it’s natural cycles.
2. Temperatures would have to track CO2 levels with a suitable lag. They don’t. Turning points in the temperature record ( 1910, 1940, 1970, 2000 ) would have to correspond to turning points in the CO2 record. They don’t.
3. The major assumption of the CO2 warming hypothesis, i.e. positive water vapor feedbacks, would have to be demonstrated in empirical data. My reading of the situation is that Spencer & Braswell, Lindzen & Choi, Miskolczi and others are winning this argument hands down.
It isn’t “global warming” that anyone is skeptical of. It is whether it is caused by anything people are doing or if anything people are doing have a significant impact on the rate/amount of warming. The globe is pretty much always “warming” or “cooling” and is rarely stable for any great length of time. The point is that nobody has shown that any current warming is at any greater rate than has occurred naturally before the industrial age.
In fact, the post-industrial warming is simply the only major warming trend we have had since the LIA. What we have measured is the recovery from the LIA till 1933, then cooling until 1976, then another period of warming till about 1998.
What is so frustrating is the constant adjusting of the adjustments. When we have a warm year that is close to 1933, it gets adjusted upward and 1933 gets adjusted downward to make a new “hottest” year. It simply would not fly in any other field of science. There is too much subjective “adjustment” applied to the records. I would want to look at rural stations that are still rural (continuously reporting notwithstanding) and see what the raw data show.
I believe the “adjustments” are corrupt and are agenda-driven.
If the objective is to determine the average trend of many stations, wouldn’t the least biased method of estimating missing data be to determine a trend for that station based on available data, and substitute the value predicted by that trend for the missing data? Then when all the data are aggregated, the trends expressed by the data for each of the stations would be weighted equally. One station would not be affecting the trend in the data from another station.
Michael Palmer
‘“Thanks for playing” – Oh? You consider this a game?’
Yes. For me, it is – my day job is in real science.
That’s a very telling statement. If you don’t consider studying the climate worthy of actual scientific effort, then, well, never mind. I’ll just take your post as seriously as you apparently do.
Adieu
Amazing that the “politicians and environmental promoters” have managed to convince 97% of climatologists and essentially every major scientific organization that AGW is real. Especially with the entire Republican party (always friends of science!) and oil and coal interests fighting tooth and nail. As a layman observer it seems clear that claiming to understand the research well enough to side with the 3% of people who know what they’re talking about is disingenuous.
This is interesting. The use of long station series seems a very good idea.
But isn’t this a similar method of taking first differences that was discussed and criticised before? See Hu McCulloch’s 2010 post at Climate Audit http://climateaudit.org/2010/08/19/the-first-difference-method/. I can’t say I understand all the arguments in that thread, but is there a better way of dealing with missing years?
beng
“I assume TOBS “models” are as trustworthy as climate models, until shown otherwise.”
TOBS is an empirically derived adjustment. you can read karls paper or the subsequent verification of it.
Essentially here is the process: for the entire united states all of the HOURLY stations were assembled. That database is then split into two parts. One part for model development the other part for model test.
Model development. Since you have HOURLY data you can calculated the following
what is (Tmin+Tmax)/2 if you record at
1Am, 2am,3am, 4am, 5am,6am, 7am etc
That gives you a Tave for every hour of the day, or rather the Tave that would be recorded IF the TOB was at a given hour.
From that your derive an offset. Like so.
Suppose that Tave at 5pm is 15C and Tave at 7Am is 14.5C
That gives you an adjustment of -.5C
This allows you to adjust ANY TOB to a common TOB. Historically, rural stations manned by individuals had TOB of 5pm.. those are “moved” forward by adjusting to the 7AM time.
Give these “deltas” an emprical model is then developed for every region of the usa. It depends upon latitude and longitude and the suns position (season) That emprical model is basically a regression.
The regression is then tested against the “held out stations” to see how well it predicts the actual
Tave. All of the standard errors of prediction are in the karl paper
CA had a whole discussion of this some time ago. At first TOBS made no sense to me then I went through some examples prepared by JerryB for john daly’s old site.
Arguing about TOBS is a waste of time. It needs to be applied in ANY analysis that does simple averages. Otherwise you will get the wrong answer. demonstrably wrong.
Brian, what about the list of possible causes of the Medieval Warm Period, the Roman, etc, or the fact that even the BEST team shows a steeper temperature rise in the early 1800’s than anything in the 20th century? Since the list of natural causes is so diminished, would you suggest pirates, jousting tournaments, and goat entrails being sacrificed to Apollo as likely forcings for those events?
Most of the apocalyptic hand waving dismissed solar effects, as the variation in visual magnitude solar output is rather small. But now we’re finding strong links between UV output and upper atmospheric temperatures, along with a possibly huge influence on cloud coverage because of cosmic ray cloud seeding, which is modulated by the strength of the solar wind, and that strength does vary strongly with solar cycles. Then they often pretend that the AMO, PDO, AO, and other natural oscillations don’t exist, and pretend that the world has statistically significant warming in the past 15 years, which it hasn’t.
If you follow some of the adjustments they make to the temperature record, we should worry less about the present getting warmer than the alarming rate at which the past keeps getting cooler. If present trends continue, millions of extra people in the 1940’s are going to freeze to death.
Brian,
After trying to help you by providing an explanation by Prof Richard Lindzen, who knows something about the subject, you come out with the 97% nonsense. That 97% number has been thoroughly debunked. In fact, the OISM Petition has far more signatures from degreed professionals in the hard sciences than the total of all the alarmist counter-petitions. The fact is that most scientists and almost all engineers reject the catastrophic AGW conjecture.
And IANAR, but tarring the “the entire Republican party” with the same brush makes you look like a credulous dope walking around with your zipper down. Run along now back to Skeptical Pseudo-Science. You need to load up on some new talking points.
Smokey,
This is the problem with arguing with [SNIP: – Policy Violation -REP] , they all have different arguments, and are willing to change them at the drop of a hat. “The earth isn’t warming!” “Ok maybe it is but it’s not humans!” “Ok it’s humans but it’s not harmful!” “Ignore the fact that I was wrong on my first two premises!”
Most scientists reject catastrophic AGW? I like that you slip “catastrophic in there. Make up your mind, are you denying global warming, AGW, or that AGW is harmful? Changing your position from argument to argument is not acceptable. Technically you may be correct, most scientists do not believe AGW will lead to armaggedon. But denying the scientific consensus on man-made climate change is absurd. http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change
Michael Palmer, I cannot thank you enough.
You have given the evidence in statistically significant swathes for what I’ve been banging on about for years. Long individual station records are essential for the proper deconstruction of the data problems, fudges and manipulations. We don’t need lots of stations, and we do not need the globe sectorized into areas of homogenized temperature soup. Surprisingly few stations will do, so long as they are trustworthy and long enough.
I did quite a lot of work on this when I had more time, some of which Anthony published here (one of my Circling Yamal pages, and my Circling the Arctic page). I also did GISS temperature records in the British Isles. And my page Removing UHI Distortion shows it’s the trustworthy US records that seem to be overall flat over the last century; worldwide there seems to be slight increase overall. Find all those pages here. And here in my “Primer are some of the prime long records, and the horrendous record of USHCN “corrections”
I was inspired by the choice of station records of the late John Daly: you, he and I are all, I think, amateur scientists, in the best sense of the word -love of real science.
“The upshot of this is that missing monthly Δtemperature values are simply dropped and replaced by the average (Δtemperature) from the other stations.”
Why do we need to do that replacement? Isn’t it possible to calculate the global temperature trend by using just the real observations?
1. Calculate the trend of one site (station) in one day of year. For example the 25th October trend in 1900..2011.
2. Do that for every site
3. Do that for every day of the year
What is the impact of changing 2. and 3. ?
If the site has been moved or there is some other changes, just consider the site closed and start a new one.
Garrett Hurley
You are picking up the wrong end of the stick. Who is it who should be expected to have coherent data on global temperatures? Is it the climate research commmunity, with salaries and pensions funded by the taxpayer and billions of dollars worth of politically mandated funding for equipment, satellites etc? Or an amateur group of scientists and concerned citizens, including some climate scientists sacked for heretical views? And you ask why WUWT does not have single party line on global temperature trends?
What has the climate science establishment done with the tremendous influx of funding over the last decade or two? One would reasonably have assumed that the first obvious thing to do would be increase the number of weather monitoring stations worldwide,making them fully automatic, with automated and correct min and max temperature recording, intercommunication and compilation. Iron out once and for all issues of area averaging, missing regions, etc.
The scandalous and unbelievble fact is that the opposite has happened. Somehow, all the new funding for climate research has been accompanied not by an increase, but a decrease in monitored weather stations worldwide, and a precipitous decline at that. WUWT? The climate community needs to defend itself from an inescapable accusation of massive fraud on almost unbelievable scale.
And now a straightforward demonstration by Michael Palmer that, sorting for the best quality continouos data records in the USA annihilates at a stroke any sign of warming on that continent, raises further the question – WHAT THE HELL HAS THE CLIMATE RESEARCH COMMINITY BEEN DOING??
BTW do mobile phones have thermometers? They should have. If they do, then someone should write an app to make a citizens’ global climate monitoing network. Mobile phones at least know where they are and what planet they are on.
@ur momisugly Bob Kutz :October 24, 2011 at 8:30 am
Thanks for a thoughtful and well-constructed post.
Brian says:
October 24, 2011 at 1:38 pm
Either this is your first time on this site and you are truly innocent and lost or else you are a troll.
As I have explained above, in line with Palmer’s thesis about stations, the reliable stations show no warming in the US. That is my position for the world. Everything that shows warming is not empirically testable.
Some people say there is warming but it is not manmade.
Professor Lindzen follows Arrhenius in saying that there is manmade warming but it is and will be harmless.
Others say that warming might be somewhat harmful but adaptation is superior to mitigation.
All of those positions fall on the sceptical side and none of them are clearly mistaken.
By the way, Smokey is as reliable a guide as one can find.
KR says: October 24, 2011 at 1:19 pm
Michael Palmer: ‘“Thanks for playing” – Oh? You consider this a game?’ Yes. For me, it is – my day job is in real science.
That’s a very telling statement. If you don’t consider studying the climate worthy of actual scientific effort, then, well, never mind. I’ll just take your post as seriously as you apparently do.
Adieu
_______________________________________________________________________
KR has got Michael’s point upside down. Thank goodness there are still real scientists like Michael who choose, in their free time, to visit an area of science that has become so corrupted that its gatekeepers are
corruptmad, proven by the fact that they proclaim they have 97% support, whilst gagging dissenters and failing to count their true number.With mad gatekeepers, I guess entry to this domain often has to be played as a game.
steven “one trick pony” mosher says:
October 24, 2011 at 1:22 pm
It’s nothing short of amazing you can use the phrase “the right answer” in regard to obtaining a global average temperature when it’s derived from instruments placed in narrow band of latitudes on a single continent. Adding insult to injury the continental region in question was the most rapidly anthropogenically transformed land area of its size on the planet.
There is no right answer from the instrument record, Steverino. Perhaps you could simply admit that no amount of pencil whipping can possibly transform this regional daily temperature sample set into a global average.
KR says:
October 24, 2011 at 1:19 pm
“If you don’t consider studying the climate worthy of actual scientific effort, then, well, never mind.”
—
I find studying the climate eminently worthy of scientific effort. What I cannot take seriously is the “reconstruction” of the “true” temperature record from a woefully incomplete and corrupted database. No amount of adjusting, correcting, weighting, averaging, extrapolating, smoothing, roughing, digesting and regurgitating will get us past the garbage in, garbage out problem.
steven mosher says:
October 24, 2011 at 1:22 pm
Wow! You actually used the word ’empirically’, though it does occur in “empirically derived adjustment.”
Given what you said, please explain one thing. How is it that you can do all your wonderful adjustments and come up with something that conflicts with the lack of a trend from the well managed stations? What is wrong with the well managed stations? Can you express this in empirical terms?
Second question. What would it take to get you to agree that our weather station measurement system is not up to the task and needs to be replaced? Is there anything that you could discover about the measurement system that would lead you to discard it? Or will you defend this system come hell or high water?
@ur momisugly Lucy Skywalker
Thanks very much for your comments. I have seen your posts here and also recently perused your own page from top to bottom and enjoyed it. I look forward to your further posts!
Best wishes, Michael
Brian says:
October 24, 2011 at 12:19 pm
This is a classic fallacy. You don’t have to present a replacement to show that a theory is false. If a theory is false, it is false all by itself.
phlogiston says:
October 24, 2011 at 2:02 pm
“BTW do mobile phones have thermometers?”
Yes they do. Too bad they have an internal heat source and are carried around much of the time in physical contact with a 98.6F warm body or inside heated/air conditioned buildings and vehicles.
You didn’t think about that question very much.
Some people say there’s no such thing as a stupid question but this one proves them wrong.
Brian says: October 24, 2011 at 1:38 pm
…denying the scientific consensus on man-made climate change is absurd.
http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change
It’s shameful gatekeeper-corrupted material like this that makes me continue banging on about establishing a skeptics’ climate science wiki, especially aimed at restitution of the most corrupted truths and rehabilitation of the most wrongfully-tarred individuals.