Guest essay by Ron Clutz
This is a study to see what the world’s best stations (a subset of all stations I selected as “world class” by criteria) are telling us about climate change over the long term. There are three principle findings.
To be included, a station needed at least 200 years of continuous records up to the present. Geographical location was not a criterion for selection, only the quality and length of the histories. 247 years is the average length of service in this dataset extracted from CRUTEM4.
The 25 stations that qualified are located in Russia, Norway, Denmark, Sweden, Netherlands, Germany, Austria, Italy, England, Poland, Hungary, Lithuania, Switzerland, France and Czech Republic. I am indebted to Richard Mallett for his work to identify the best station histories, to gather and format the data from CRUTEM4.
The Central England Temperature (CET) series is included here from 1772, the onset of daily observations with more precise instruments. Those who have asserted that CET is a proxy for Northern Hemisphere temperatures will have some support in this analysis: CET at 0.38°C/Century nearly matches the central tendency of the group of stations.
1. A rise of 0.41°C per century is observed over the last 250 years.
| Area | WORLD CLASS STATIONS | |
| History | 1706 to 2011 | |
| Stations | 25 | |
| Average Length | 247 | Years |
| Average Trend | 0.41 | °C/Century |
| Standard Deviation | 0.19 | °C/Century |
| Max Trend | 0.80 | °C/Century |
| Min Trend | 0.04 | °C/Century |
The average station shows an accumulated rise of about 1°C over the last centuries. The large deviation, and the fact that at least one station has almost no warming over the centuries, shows that warming has not been extreme, and varies considerably from place to place.
2. The warming is occurring mostly in the coldest months.
The average station reports that the coldest months, October through April are all warming at 0.3°C or more, while the hottest months are warming at 0.2°C or less.
| Month | °C/Century | Std Dev |
| Jan | 0.96 | 0.31 |
| Feb | 0.37 | 0.27 |
| Mar | 0.71 | 0.27 |
| Apr | 0.33 | 0.28 |
| May | 0.18 | 0.25 |
| June | 0.13 | 0.30 |
| July | 0.21 | 0.30 |
| Aug | 0.16 | 0.26 |
| Sep | 0.16 | 0.28 |
| Oct | 0.34 | 0.27 |
| Nov | 0.59 | 0.23 |
| Dec | 0.76 | 0.27 |
In fact, the months of May through September warmed at an average rate of 0.17°C/Century, while October through April increased at an average rate of 0.58°C/Century, more than 3 times higher. This suggests that the climate is not getting hotter, it has become less cold..
3. An increase in warming is observed since 1950.
In a long time series, there are likely periods when the rate of change is higher or lower than the rate for the whole series. In this study it was interesting to see period trends around three breakpoints:
- 1850, widely regarded as the end of the Little Ice Age (LIA);
- 1900, as the midpoint between the last two centuries of observations;
- 1950 as the date from which it is claimed that CO2 emissions begin to cause higher temperatures.
For the set of stations the results are:
| °C/Century | Start | End |
| -0.38 | 1700’s | 1850 |
| 0.95 | 1850 | 2011 |
| -0.14 | 1800 | 1900 |
| 1.45 | 1900 | 1950 |
| 2.57 | 1950 | 2011 |
From 1850 to the present, we see an average upward rate of almost a degree, 0.95°C/Century, or an observed rise of 1.53°C up to 2011. Contrary to conventional wisdom, the aftereffects of the LIA lingered on until 1900. The average rate since 1950 is 2.6°C/Century, higher than the natural rate of 1.5°C in the preceding 50 years. Of course, this analysis cannot identify the causes of the 1.1°C added to the rate since 1950. However it is useful to see the scale of warming that might be attributable to CO2, among other factors.
Of course climate is much more than surface temperatures, but the media are full of stories about global warming, hottest decade or month in history, etc. So people do wonder: “Are present temperatures unusual, and should we be worried?” In other words, “Is it weather or a changing climate?” The answer in the place where you live depends on knowing your climate, that is the long-term weather trends.
Note: These trends were calculated directly from the temperature records without any use of adjustments, anomalies or homogenizing. The principle is: To understand temperature change, analyze the changes, not the temperatures.
Along with this post I have submitted the World Class TTA Excel workbook for readers to download for their own use and to check the data and calculations. You can download it from this link: World Class TTA (.xls)
For those who might be interested, the method and rationale are described at this link, along with the pilot test results on a set of Kansas stations:
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njsnowfan says:
July 28, 2014 at 10:06 am
At first glance, the temperature increases seem match increases in solar activities from the period.
Hardly. Here is our ‘best’ estimate of solar activity the past ~250 years: http://www.leif.org/research/New-Group-Numbers.png
Ron C. says:
July 28, 2014 at 11:25 am
++++++++++++++++
Thank yo Ron.
Is there a seasonal variation to UHI? I realize it depends on the particulars, but I was wondering if anyone had studied the general problem.
This data gives a good insight into what has happened in northern Europe. I trust original data more than “adjusted” as do many others. There seems to be a definite warming trend with quite a bit of variation. I am not surprised as I have found quite a bit of variation between stations that are less than 20 miles apart here on the south coast of the UK. If CO2 was the main cause of warming all over the world then surely we should see a much more uniform warming.
“Richard Mallett says:
July 28, 2014 at 10:00 am
For my list of 28 best stations (Ron dropped one of each pair of stations from the same location) the annual trend from 1979-2010 (the limit of CRUTem4) is +4.78 C/century and from 1998-2010 is -1.77 C/century.”
Whoa!
Serious downturn lately.
graph from Boehm et al 2009 showing “homogenisation” applied. Note that summer temps show virtually no rise since 1750 until “corrected”. Note Dr. Phil “why should I give you our data, you only want to find something wrong with it” Jones, is one of the co-authors.
http://climategrog.wordpress.com/?attachment_id=999
Several of the HOSTALP sites have interesting long records but are heavily manipulated long term Several sites in this group were used here.
What is worse is that raw data is a closely guarded secret requiring a substantial fee and a non-disclosure agreement to even get a copy. This means that these substantial additions to the long term variability can not be verified and any one who found a conflicting result would not be able to publish a contrary study that itself could be reproduced because he’s not allowed to publish the data.
TRG says:
July 28, 2014 at 12:39 pm
Is there a seasonal variation to UHI? I realize it depends on the particulars, but I was wondering if anyone had studied the general problem.
Make that “variation to UHI effect at each station” and not just seasonal, but perhaps even daily. Besides the environmental static items (such as asphalt pavement) that have an effect, there are the dynamic items such as wind, cloud cover, and humidity.
Individual, improperly sited stations give a warmer than correct reading and the probability that they are being adjusted to a proper reading is extremely doubtful.
Ron C. says:
Greg Goodman
This study did not aim to critique the quality of the temperature data itself. We were interested in seeing the trends arising from CRUTEM4 data taken at face value. In the post, my comment means that we did no adjusting, anomalies or homogenizing to the data in our method of analysis.
====
Thanks Ron. Then you probably need to make this clear in the article. It currently says:
“Note: These trends were calculated directly from the temperature records without any use of adjustments, anomalies or homogenizing.”
Now you’ve “explained” what you meant, it can be read that way but several people have questioned you on the same point. It is misleading.
If you mean “I have not added any homogenisation to the substantial manipulations already made to the data to make if conform to AGW thinking” , you need to make it clear that is what are saying.
Currently you give the impression that the data is not homogenised at all and that is very misleading.
it seems that the data is essentially worthless; all high urban stations, Paris, Berlin, Prague, Stockholm, Turin, St Petersburg… No wonder the temperature is skyrocketing in the 20th century.
Reply to Ivan :-
Trend from 1702 to 1900 is -0.15 C per century. Trend from 1900 to 2010 is +1.33 C per century. That doesn’t conform to my definition of sky-rocketing.
Derek says:
This data gives a good insight into what has happened in northern Europe. I trust original data more than “adjusted” as do many others. There seems to be a definite warming trend with quite a bit of variation.
====
Sorry Derek, you too have been mislead by the author’s description. This data is _heavily_ adjusted ( just not by Ron ).
Anthony, perhaps you could encourage Ron add a clarification. This data , especially the several HISTALP stations used here has far more “homogenisation” problems than the USHCN that has been getting so much press recently.
Were talking 0.5 deg C or more of “corrections”, just to the summer temps:
http://climategrog.wordpress.com/?attachment_id=999
Worse, the HISTALP group are just a secretive and obstructive as Phil Jones and unlike the US data, no one gets to look at the raw data and do some auditing.
Did you know the greenhouses in Almeria Spain have reduced the exterior temperature.
http://www.dailymail.co.uk/news/article-2303943/Britains-vegetable-garden-The-sea-Spanish-greenhouses-large-Isle-Wight-food-eat-grown.html
Ron C says: “This study did not aim to critique the quality of the temperature data itself. ”
Well it does because you present this as a specially selected group of “world class data”. I really don’t see that you have done any QA other than picking long records. Which, as Mosh’ and others have comments, in no way guarantees quality.
Indeed you did not “critique” the quality but maybe you should have done before applying the epithet “world class” to it.
Temperatures from Uppsala and Stockholm has been discussed at ‘Klimatupplysningen.se’ in three threads. Even if it is written in Swedish the graphs and pictures are informative.
My personal reflection is that you always get into difficulties when you use data for a purpose they where not collected for.
For those of you that look for amusement I think this citation may make your day:
“Hur snurrigt det här än låter så verkar det som att Uppsalas väder bestäms av en väderstation utanför staden vid F16. Uppsalas (och Sveriges) klimat uppmäts av en station i Uppsala.”
My translation:
“Despite the oddity it seems that the weather in Uppsala is determined from a station outside the city at the air force base, F16. The climate in Uppsala (and Sweden) is measured by a station inside the city.”
Link, to a thread that has links to the other two:
http://www.klimatupplysningen.se/2014/04/08/uppsalatemperaturer/
Don’t forget the affect of Clean Air Acts on 80’s-90’s in Europe causing 25% approx of warming
http://onlinelibrary.wiley.com/doi/10.1002/2014GL060798/abstract
darwin wyatt says:
July 28, 2014 at 12:12 pm
Welcome to the end of the LIA… Expect glaciers to retreat even more and spruce forests to establish like during the MWP.
========================================================================
and Vikings will once again return to flourish in Greenland. Sharpen the axes.
“TRG says:
July 28, 2014 at 12:39 pm
Is there a seasonal variation to UHI? I realize it depends on the particulars, but I was wondering if anyone had studied the general problem.”
Not sure about seasonal, but there is a variation with prevailing conditions…cloudy/sunny and it’s also not uniform during the day. On a bright, clear, sunny day, it will be more pronounced than on an overcast one. It should also peak in the mid/late afternoon.
Just a simple, not very accurate test the past few weeks show up to a 6F difference along the main street of my little town. On a clear, sunny day from the grocery store to the gas station is about 6F warmer than even a block on either side. It’s all pavement, buildings and concrete. No trees or anything else. The buildings are tall enough (3 to 5 stories) to block most of the wind, so it’s also a pretty dead space. On cloudy days it’s about 2-3F difference. It also stays at that 2-3F through most of the night, if not all night (no, I haven’t checked much at 5 AM).
And no, it’s not being done with a very accurate thermometer…but it is consistent with itself and it’s response time is good enough to get a stable reading while stopped at the traffic light I’m using as a reference point.
It also seems to diminish, but not completely disappear if there are several overcast days, with fairly uniform temperatures and little separation between high and low, in a row.
UHI is NOT a uniform correction factor.
Ron C. says:
Greg Goodman
Yes, there is a fine line between quality control of errors, and tampering. The studies mentioned are done by NMSs, who are the people producing, verifying and submitting the data. I tend to believe they are trying to get the record right.
=====
Thanks again, Ron. However, UEA’s CRU is not a national weather service. Their top man said he’s rather delete the data if he ever got forced to hand it over ( a criminal act under the law of England and Wales) . He also said he would “hide behind” intellectual property arguments to avoid releasing the raw data. Then they “lost” it.
The HISTALP group a similarly secretive and obstructive and same P.D.Jones is a co-author on the paper ( Boehm et al 2009 ) that explains their ‘homogenisation’. In fact they hold international meetings on “data homogenisation” to ensure that all their methods give results that are ‘homogeneous’. Don’t want some “poor quality” data telling the wrong storey , do we.
There is no reason to be over cynical but having seen behind the curtain, and read some of what this little team of zealots were getting up to, there is no longer grounds for a generous presumption of good faith. You have the right to that before you get caught being cheating and manipulative.
Once gone trust does not come back.
We came out of an ice age about 150 years ago? An age? So temperature observations have been going up some? (yawn)
The idea of finding “world class” stations is excellent. It lends itself to a solid PR strategy. Focusing on getting more and more credible raw data is a winning topic for skeptics.
The main thing I got from this post was winter is getting less cold. I understand what that means, but I don’t like the way it sounds. Imagine the headline: “Global warming skeptics: It’s not getting warmer, it’s getting less cold.” The “convinced” would have a field day with it.
Maybe that statement has scientific underpinnings, but it sounds so much like bureaucratic gobbledy gook I would hesitate to use it, Thankfully you explained it. Even though it takes more time and uses more words, the full explanation sounds far more credible to my ear than “it’s getting less cold”.
Thank you for sharing the spreadsheet.
Ron, first, my thanks for your interesting work. Right or wrong, it’s good to see people doing their own research.
That said, I didn’t see the criteria you used to select your stations. You state:
While the length of the histories is easy to determine, how did you determine the “quality” of the records?
I ask because it is far from a trivial problem. Most, perhaps all, long term station records contain instrument changes, location changes, shelter changes, time-of-observation changes, or other alterations that can significantly change the size and even the sign of the trend. How did you winnow these records for “quality”?
In this regard, you say:
Let me explain what you are actually saying:
I fear you’ve forgotten the old maxim, “Garbage in, garbage out”. When your data contains known problems, as almost all temperature records do, using them as-is is just GIGO.
As I said, I give you high marks for doing the work, explaining it clearly, and providing your data and code. That is how science is done.
However …
Best regards,
w.
PS—In addition, I was surprised not to see the Armagh Observatory record among the ones chosen. What was your reason for rejecting it?
Reply to Willis Eschenbach :-
I selected the records, based on the criteria I explained to Ragnar.
Regarding Armagh, the record starts in 1844, so it would have been of no help in determining trend before 1850. I wanted to compare trends before and after 1850. It was convenient that this gave me 148 years before 1850, and 160 years after 1850.
Are there any long temperature records that are not ‘shonky’ or error ridden ?
My originally selected set of 28 temperature records (Ron eliminated 3 duplicates) gave a trend since 1702 of +0.26 C per century since 1702. What do you suggest we do to improve the quality of this figure, while maintaining the value of its longevity ?
Matt L.
The definitive answer comes only by analyzing TMaxs and TMins to see which one is driving the rising TAvg. But the results here suggests that winters are milder, springs earlier and autumns later–What’s not to like? JR Wakefield proved that to be the case in Ontario.
What we are seeing with the lows getting warmer and the highs getting cooler is a thermodynamic Regression to the Mean. It is a mathematical artifact of the sparse sample size over land and a too short measurement period.
With the Satellite data we will continue to see the same thing until we get a long enough data period. Adding data points, like Argo, will shorten the time period to the regression to the mean and show an increased rate of warming until then.
We will continue to see the same warming trend in the near future but at a declining rate.
The reason we see the Regression to the Mean and the warming is because the ocean surface temperature is the Mean and it has on average, warmer lows and lower highs than land surface measurements.
Instead of increased CO2, I would bet on increased irrigation and surface area of reservoirs and plowed fields of decreased albedo as playing a larger role (if any) in temperature increase.
Ron C.
… the results here suggests that winters are milder, springs earlier and autumns later–What’s not to like?
Nothing. I like it fine. But I like the way you wrote it in the quote above better than “it has become less cold.”
If this article spawns a peer reviewed paper, the peers will likely “get it”.
If this article gets picked up by MSM, “it’s not becoming warmer, it’s becoming less cold” will come across differently to the public.
First of all, thanks for publicly sharing your results and your method and for the time and effort required to look at the record from a new perspective. I noted with some interest that all the stations were in countries in the northern hemisphere. As the CAGW community was so fond of saying when trying to diminish the MWP, we have no way of knowing if the results are global in nature. But unless we’re willing to dig through Southern Hemisphere records, we also have no way of knowing they aren’t. Food for thought.
Reply to The definition guy :-
The only Southern Hemisphere stations with data from before 1850 are Rio de Janeiro (started in 1832, first reliable year 1851), Pamplemousses, Mauritius (1787-1960, only 62 of 174 complete years, and only 3 years before 1850) and Hobart, Tasmania (started 1841, first reliable year 1883)