Guest post by Tony Brown
This short paper is a preliminary examination of BEST data to 1753, as compared to the Central England Temperature Record (CET) to 1660 (instrumental record) and 1538 (Extended by Tony Brown using thousands of contemporary observations)
This extension to 1538 was a central part of my article ‘The Long Slow Thaw,’ which also examined historic temperature reconstructions by Dr Michael Mann and Hubert Lamb
http://judithcurry.com/2011/12/01/the-long-slow-thaw/
In the article, warming from the start of the CET instrumental record in 1660 to the present day was noted, albeit with numerous advances and reverses.
The extended CET record coincides well with a 2000 year reconstruction by Craig Loehle here;
http://www.econ.ohio-state.edu/jhm/AGW/Loehle/
And one by M. V. SHABALOVA and A. F. V. VAN ENGELEN : Evaluation of a reconstruction of winter and summer temperatures in the Low Countries, ad 764–1998
http://www.springerlink.com/content/gu62270140g7r854/
According to studies made by a number of climate scientists, CET is a reasonable proxy for Northern Hemisphere -and to some extent global temperatures- as documented in ‘The Long Slow Thaw’. However, as Hubert Lamb observed, it can ‘show us the tendency but not the precision’. In that light there are a number of comments that can be made about the Combined CET/BEST graph which are shown above in two versions that, viewed together, provide the opportunity to follow the ups and down of the ever changing climate over the 350 years of instrumental records.
(Note; The BEST extension to 1538 and the extension to both trend lines after 2012 in the first graphic are merely a graphing feature.)
There are a complex set of important UHI corrections applied to CET and described by the Met office as follows.
“The urbanisation corrections to the CET series have been applied since 1974. Initially they were just 0.1 degree C, in certain months, then gradually for more months of the year; from about 1995 onwards some of the corrections increased to 0.2 deg C, and by about 2002 all the corrections were 0.2 deg C.
The above applies to Mean CET. The urban heat island effect is much more noticeable for minimum temperatures than for maximum, so for the Minimum CET series the corrections are double those for Mean Temperature, whereas for Maximum Temperature it was deemed in fact that no correction was required.”
That the Met Office correct for urbanisation is interesting in itself, whether it is sufficient is also a matter of debate, but is outside the current scope of the current paper. BEST do not correct for UHI, in fact they make some mention of it having a cooling effect.
The crossover point of BEST and CET around 1976 –when BEST starts to rise steeply- may or may not therefore reflect that one record allows something for uhi whilst the other doesn’t.
CET has been in steep decline since around 2000.
http://www.metoffice.gov.uk/hadobs/hadcet/
BEST has been broadly level in recent years, which does not reflect the reasonable historic correlation between the ‘tendency’ of the two graphs as can be seen by following the trend lines since the start dates, albeit those of BEST seem at times to be exaggerated, perhaps reflecting Britain’s temperate climate.
The cold BEST period around 1750-1760 possibly reflects the very small number of stations used in their reconstruction-all in the Northern Hemisphere-which are not necessarily as representative of the global climate as CET has been found to be. Also, most of them were part of the Mannheim Palatine-a network of stations that predated GISS by 200 years. Each of these older stations have been very thoroughly scrutinised and their temperature record often adjusted downwards under the EU funded ‘Improve’ programme, as it was generally felt there was a warm bias.
The BEST trend line from 1753 to the present day is somewhat exaggerated through not being able to reflect the very warm period centred round 1730 which would provide a better balance than starting the record in a trough. The CET warming period from 1690 to 1730 (un-paralleled even in the modern record ) is well documented by such as Hubert Lamb and was noted here in the 2000 book ‘History and climate-memories of the future?’ This chapter from Phil Jones-page 61;
‘All five series show long term warming from either the late 18th or early 19th centuries. Recent years are only marginally the warmest of the entire series because of the warmth of the 1730′s (particularly in Western Europe) and the 1820′s (Northern Europe) The five series are CET, De Bilt, Berlin, Uppsala, Stockholm.’
That the start of the temperature rise noted in ‘The Long Slow Thaw’ precedes the start date of GISS and Hadley by many centuries is illustrated by Tony Brown (CET extended), Craig Loehle (revised reconstruction) M. V. SHABALOVA and A. F. V. VAN ENGELEN, and BEST. In this context such records as Hadley, GISS, and even BEST itself, can be seen as merely plugging into the long established warming trend at various points along the way, and do not mark the start of it. There is no sign in observational records, or in many well regarded scientific reconstructions, of the 900 year long sequence of gently falling temperatures as noted by Michael Mann in the ‘hockey stick’ handle, nor an ‘uptick that is any more notable than many periods in the past.
That there was a gradual warming of winter temperatures-the severity of which had substantially reduced the overall mean annual temperature during much of the earlier historic record- was noted by Reginald Jeffery in his book ‘Was it Wet or was it fine,’ written in 1898.
“By 1708 the middle aged would say where are our old winters?”
TO MODS – IMPORTANT
Joanne Nova site says it is “Forbidden” and the British http://www.thegwpf.org says “account suspended”.
This looks like a coordinated attack to me – be vigilant.
REPLY: NO worries, see front page – Anthony
“BEST do not correct for UHI, in fact they make some mention of it having a cooling effect“.
BEST do indeed not correct for UHI. Muller, Curry et al published results of a study they did to try to detect UHI, and they did indeed say that they detected a possible cooling effect but thought it very unlikely and ignored it.
As I pointed out in a WUWT comment at the time, their UHI-detection methodology was seriously flawed. What they did was to use MODIS satellite data to identify the bright spots caused by quite large cities, and treated stations outside those spots as rural. The problem is that UHI is not exclusively related to city size, and development in even small urban areas can affect temperature trends. I did a very quick check of the list of stations that BEST supplied to me on request. I concentrated on Australia, and found that of the 800 or so stations listed as rural, over 100 were at airports and over 100 were at post offices. The idea that these stations were truly rural is laughable, especially in light of the more recent Watts 2012 study of station siting.
In the winter of 1708-09, Europeans of all ages would have yearned for warmer weather.
http://en.wikipedia.org/wiki/Great_Frost_of_1709
The extreme conditions of that winter had a big impact on world history, to include weakening Charles XII’s Swedish army in the Ukraine, defeated by Peter the Great at Poltava in June/July 1709.
Perhaps it would be use to draw a distinction between general urban heat islands. And the (possibly equivalent) microclimate consequences of station siting. BEST may not have had the methodology to discern the latter; MODIS stands for moderate resolution.
Good points Mike. And if we think back to yesterday’s post, I imagine that the Lake Tahoe station is rural but could be impacted by having a trash burning bin adjacent to the station. I wonder if this blog was the only site to cover that.
Hi Tony
Informative as usual. Your pre-1660 reconstruction should be taken note of; current temperatures are nothing exceptional, only fraction higher (about 1/4 degree C, well within margin of error) then 400 years ago.
Brilliant work Tony! And a lot of it too, to compress into a short vignette. Hopefully you can provide follow-on articles along the lines of ‘The Long Cold Thaw’. It seems quite obvious that many climate scientists have their heads stuck up computer models or dodgy treemometers. A trip to the real historical record would do them good. Also, it would be fascinating…
I would like to see some indication of the significance values applied to these slopes. The CET data is noisy enough for a 0.0013 slope to be possibly spurious.
The BEST data may be more significant, but since it starts at a low point in the CET, an increase in temperature over its period of record may be an artefact of its starting point, rather than a significant trend.
Thanks TonyB. I’ve also noticed this. Berkeley Earth has a 48% higher trend for the United Kingdom than the official HadCentralEnglandTemperatures going back to the start of Berkeley in 1743.
The only explanation is that their record-splitting by identified breakpoints algorithm is faulty.
http://s8.postimage.org/mdjgdalmt/Berkeley_UK_vs_Had_CET_1753.png
Berkeley is also 28.3% higher for the US (lower 48) than the NCDC back to 1895 which we know has already adjusted the trend up by some 0.5C to 0.84C already. Berkeley was supposed to be using raw data. Not homogenized and TOBs-adjusted and a 28.3% adjustment increase added on top.
http://s11.postimage.org/3suobq4kj/Berkeley_US_vs_USHCN_1895.png
Sunshinehours has been documenting the same issue with individual states.
http://sunshinehours.wordpress.com/
This is not an insignificant problem that must be addressed. Until it is, we have to assume the Berkeley Earth temperature series is faulty by significant margins.
“CET has been in steep decline since around 2000.”
No, not really. 2010 was a cool year, but otherwise the temperature have been holding pretty steady.
To be more precise, here is the results for a linear regression fit to the Annual CET data for 2000-2011.
The regression equation is
T(2000-2011) = 89.2 - 0.0393 YEAR
Predictor Coef SE Coef T P
Constant 89.15 89.63 0.99 0.343
YEAR -0.03934 0.04469 -0.88 0.399
S = 0.534431 R-Sq = 7.2% R-Sq(adj) = 0.0%
So the linear fit explains basically 0% of the variation, and the trend (which admittedly is downward at -0.4K/decade) is not statistically significant (p-value = 0.4 >> 0.05). This is a far cry from a “steep decline”, although it is also a far cry from warming. I few more cool years might make the drop significant. A few more years of warming could erase the downward trend.
The 1991 paper below documents how the CET was constructed.
It contains monthly trends and these show that all the warming is in the winter months (October to March). Were UHI due to retention of solar heating thru low albedo surfaces, the Urban Canyon Effect or other mechanism, this should occur primarily in the summer. The winter warming trend (as well as increasing minimum temperatures) is consistent with my argument that the post 1950s warming is due to reduced urban aerosols, which in the UK would have been primarily from the domestic burning of coal in the winter months.
There is also a winter warming trend starting from the late 19th century. This might be related to the replacement of gas lighting – notorious for soot and sulphate emissions- by electric lighting, which started in the 1890s and was largely complete by 1930.
http://www.metoffice.gov.uk/hadobs/hadcet/Parker_etalIJOC1992_dailyCET.pdf
Tonyb,
Great work as always. One thing I would like to see people do when presenting temperature series like this is to put it in proper perspective. Anomalies exaggerate the fluctuations. Itz like looking at an ant with a magnifying glass. Oooooh, sssssccccaarrryyy… but take the magnifying glass away and it is just an ant. Plot that graph using the baseline temp on a scale relevant to the human experience, like -40 to +40 and suddenly all those “huge” fluctuations, past and present, stand out for what they really are. Pretty much flat.
This gradual warming also sits well with solar/galactic cosmic ray activity.
A station in NE Oregon was in the local paper this year due to an award given to a person connected with it. The picture shows tree limbs hanging over and down the side of the Stevensen screen. Unfortunately, the volunteers that spent their days recording data without fail, were clearly not provided with the guidance needed to keep these sensors artifact free. This rural sensor is a prime example of why city lights are no measure of UHI affects. It sits in a county entirely devoid of stop lights.
The extreme conditions of that winter had a big impact on world history, to include weakening Charles XII’s Swedish army in the Ukraine…
=================
I think I can spot the defeat of Napoleon’s Grande Armée (1812) in there also.
I used to think I was so lucky to have enjoyed a few childhood years in the 40s when the planet was at the optimum temperature (before Man began to cause dangerous climate change™); then Muller came along and declared “…I concluded that global warming was real and that the prior estimates of the rate of warming were correct. I’m now going a step further: Humans are almost entirely the cause…”.
According to Muller the global land temperatures have increased 1.5 C since c. 1750.
A temperature rise of that magnitude must have caused considerable climate disruption, species extinctions, not to mention earthquakes etc. ( http://www.numberwatch.co.uk/warmlist.htm ).
Or did the human-caused warming 1750 – 1980 (1990 or 2000?) merely restore global temperatures to an optimum level, only further rises being perilous?
“The Little Ice Age” by Brian Fagan is an excellent exposition of why warm is good and cold is bad. For those in Northern Europe, it was a truly horrible time. What a shame Mann, Hansen and co. could not experience it, or they might change their incessant keening about recent temperatures.
“””””…..Mike Jonas says:
August 14, 2012 at 2:26 pm
“BEST do not correct for UHI, in fact they make some mention of it having a cooling effect“.
BEST do indeed not correct for UHI. Muller, Curry et al published results of a study they did to try to detect UHI, and they did indeed say that they detected a possible cooling effect but thought it very unlikely and ignored it……”””””
There is absolutely nothing wrong with UHIs, or their being included in Weather station Temperature records. They are actual physical places that have a real measurable Temperatures.
What IS WRONG is believing that it is valid to use that Temperature to represent the Temperature of other places up to 1200 Km away from the UHI thermometer.
Also UHI s radiate faster and at shorter wavelengths that are less susceptible to CO2 interception. So I would expect UHI s like the tropical deserts to be good for cooling the earth. The polar regions certainly don’t do anything useful to cool the planet.
Gill et al 2007 did a study showing greening roofs in Manchester (England) reduced the local temperature by 4C (I haven’t read the full paper) and I recall reading up to 10C could be achieved in Rio de Janeiro
.
Seems to me, if greening roofs in Manchester can reduce the local temperature by 4C, then concreting over chunks of land can raise the temperature locally be 4C.
Further to my comment, I was reading a presentation by Sarah Lindley (Manchester University) in which she tells us:
Btw, SCORCHIO is areference to a character from the Fast Show where the weather girl describes the weather forecast ia slways “scorchio”
cui bono
Thanks. I will be expanding on this work-in particular I want to examine the period around 1730 which seems little different to today. It takes me about six months to research material for a major article such as ‘The Long Slow Thaw’ but a few snippes-such as this one-tend to naturally fall out of the wider research.
tonyb
tjfolkerts.
The ‘steep’ declne is shown in the graph from the Met office (|back to the levels of the 1730’s) Also anecdoally the gardening weathe has changed. It has become more diffcult to grow outdoor tomatoes, cucumbers and runner beans for example, whilst many of the succuents we have taken for granted can be grown outside have suffered very badly even in my garden in the mild South West of England.
All our attention is focused on warming, I think we need to have a plan ‘b’ for cooling
tonyb
Seems to me, if greening roofs in Manchester can reduce the local temperature by 4C, then concreting over chunks of land can raise the temperature locally be 4C.
Concrete has a high albedo (fresh concrete around 0.55) and is therefore a cool surface relative to most surfaces. In fact there is much discussion in urban planning circles about using high albedo concrete to reduce UHI.
Urban centres tend to have relatively high levels of concrete surfaces (as well as high albedo reflective glass) compared to suburban areas and this could have been the reason BEST found urban cooling.
Can we keep away from graphs with red/green in them? 30% of males are like me, unable to follow graphs like these. Can we have some dots and dashes to assist?
Much has been claimed for the Central England Temperature Record but is it that reliable?
I would not have thought so. Thermometers were not very good back then as no standard had been established or accurate method of calibration. OK so we have two points, melting point and boiling point of pure water but these depend on atmospheric pressure which complicates the calibration, at least to the accuracies required. There were no stations back then where thermometers could be sited to a standard only rich landowners who had time on their hands and the money to buy a thermometer. (Remember back then Newton paid £3 for a quartz prism to do sunlight spectra experiments which was several month’s salary then). Readings were taken at odd times by some with no training so data sets would have been limited to say the least.
So is the CET a good basis to use for current discussion about past climates?
I do not think so.
Tony:
Thankyou for this article. As always, you provide ‘good stuff’. And it gives me great pleasure that at last – and after all my pleading – you have started to present your work on WUWT.
My reason for writing now is that I notice you have had some interaction with tjfolkerts in this thread, and I suggest that direct communication and interaction between the two of you would be beneficial.
I said to him on another thread
Richard