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?”
Vuk
If all the rythms coincided it woulds be enough to make you believe in gaia
tonyb
Steven Mosher – For their UHI study, BEST used “the MODIS 500m Global Urban Extent classification map (MOD500)“, and yes, I described it incorrectly. However, the main point remains, namely that it is useless for identifying the impact of development.
Even examining the satellite data down to a single pixel, as you have been trying to do, doesn’t solve the problem. A MOD500 pixel (as per the BEST paper berkeleyearth.org/pdf/berkeley-earth-uhi.pdf) is 15 arc-seconds, ie. nearly 100m. As Watts2012 showed, what matters most is what is going on a lot nearer than 100m to the station. It seems the only real solution is to examine each individual station properly, ‘on the ground’, which is where surfacestations.org started.
In reality, it’s altogether too much work, so I suspect that the solution will be to find a relatively small number of well-distributed long-life well-sited stations, and to use just those.
Not to my eyeball. In Loehle’s graph, the 1920s/30s (Loehle corrected only goes to 1935) are nearly half a degree C warmer than the 1540s/5os, and nearly 1C warmer than the early 1600s. In your CET extended, all these periods appear to be about the same temperature. There is a clearly and sharply rising trend in Loehle’s reconstruction from the 1540s, but there is a much shallower trend in yours. While there is some similarity in ‘tendency’, there are some very strong dissimilarities, too, From 1700 to 1800 in Loehle’s, there is a very sharp increase. This is not apparent in your CET graph. From 1600 to about 1675 there is a definitie downward trend in your CET chart. In Loehle’s, the trend is clearly upward.
I was curious to see how you corroborated the notion that CET are a sound proxy for NH temperatures. After reading Long Slow Thaw, I’m impressed by the detail, but not with the conclusion on that as given above (“CET is a reasonable proxy for Northern Hemisphere”) as applied to assess the validity or otherwise of millennial reconstructions.
I agree that MBH99 did not display the variability inherent in its own data, and emphasised in later studies, including by Mann. But I think a simpler argument may be made just be showing more up-to-date reconstructions from the literature, including those by Mann, which show this well enough. I understand that the ‘hockey stick’ is so iconic for some (in a political sense) that it is still being mulled over more than a decade after its publication and despite a slew of superior work on offer that verify its basic conclusions, if not the implied long, slow decline of temperatures since 1000, but OTOH, can we stop beating the moribund nag yet?
oops, 15 arc seconds is more like 450m, that’s much worse. http://www.esri.com/news/arcuser/0400/wdside.html
says: August 16, 2012 at 1:47 am
If all the rythms coincided it would be enough to make you believe in gaia.
Belief is an individual’s choice, I am not really into ‘gaia theory’, apparently it was surpassed before I got to hear about it .
If there are number of oscillating systems loosely connected, then after period of time the dominant one (in this case sun) would eventually pull the less stable ones into a common frequency.
Nature abhors coincidence, it is ruled by laws of cause and consequence.
Anthony, this has probably been mentioned before, but hopefully Josh can run a cartoon of Hansen and Gore caught painting thermometer boxes black.. and the cop says: “YOU again!” whilst arresting Hansen..
barry
I stress that CET shows the ‘tendancy but not the precision’ and this can be seen in the BEST global graphs where there are some clear correlations, albeit that CET is generally more moderate.
I think precision is impossible in any proxy type graph, especially the further back in time one tries to stretch, which brings into play some dubious proxies (tree rings as accurate proxies? Sorry, no).
In this respect. I comment specifcally on the very earliest part of my reconstruction, that the 1540’s/50’s need closer examination as it appears to be a significant period. (i was interested in the French quotation in the comments and that Lamb saw this as a warm period.)
I had expected the early 1600’s to be as cold as the latter part of that century but it would appear that it wasn’t.
As for Dr Mann, the hockey stick is still, to this day, an icon, and all other reconstructions are measured against it. I do show plenty of ‘spaghetti’ alternatives, but ultimately it is the slight downwards trend from 1000AD with very little variability until its dramatic uptick that remains the take home message for the publc, politicians and activists, and one that our own Met office adhere to in their belief of the lack of variability.
I am acquiring numerous pieces of documenttry records from a variety of sources to reconstruct further back firstly to 1200, and in the process try to identify if there is clear evidence of a change from MWP to LIA.
Do I think that CET is a better proxy than the hockey stick? Yes I do, albeit that global temperatures is perhaps a pointless measurement and any proxy isnt going to shpw the temperature shape fpr the entire globe.
tonyb
Tony, your CET temperature records and pre CET proxy records, backed up by extensive historical records, would seem to give a truer record of temperature trends than BEST.with its low temperature starting point, omission of the well documented MWP and apparently no 20th century adjustments for UHI . Your exhaustive, (possibly exhausting as well :-)) examination of historic records provides a valuable cross referencing of the science, what Winston Churchill referred to in military map making, as taking a cross bearing. And no tweaking of models or suspect tree ring studies involved.
Tonyb,
the current information from the Met Office on past temperatures is as follows;
http://www.metoffice.gov.uk/climate-change/guide/faq
This is based on updated millenial reconstructions.
The Met Office page you link to in order to support your contention that the Met Office defers to MBH99, is an archived page, not current. Here again, you are beating a dead horse.
You say:
“As for Dr Mann…”? Why bring personality into a comment about an iconic graph? What about Dr Mann is so important that you include him in this sentence? You do not finish your opening here – “As for Dr Mann…” what? I detect a personality based argument that you don’t quite go for.
In any case, where in the world is the hocket stick the measure of all other reconstructions? I mean, apart from skeptic blogs and other critics of it, who in the mainstream is holding MBH99 as some kind of standard for other reconstructions? The only reason MBH99 is a current issue is because of skeptics criticising it, not because of anyone else.
Please corroborate your assertion here (minus the personalities, please).
I applaud your seeking to extend the temperature record, but wonder if you are relying too heavily on anecdotal evidence. And I think it is unwise to consider Lamb’s 1965 graph, with little information supporting it, no Y-axis figures, and data only to the mid-20th century, as a reliable representation of past – and certainly recent – temperatures. Science has moved on. so should we.
Re yr comments on CET 1540 – 2012 and Loehle 1540 – 2000, Barry, my eye-balling sees correspondence. On Michael Mann, hmm, disregarding his many public diatribes in defence of his HS, it was analysed in depth and found wanting, both on data selection and statistical method, and follow up Hockey Sticks have fared no better, including Gergis et al, which has now been withrawn from publication.
Barry
As Beth says Dr Mann is still an important figure and the hockey stick still much referenced. Science moves on but leaves consequences in its wake. The Met office for many years has maintained that there was little variability as did the IPCC. Dr Mann was perhaps their role model or merely a standard bearer of a view that had become fashionable.
What we are left with is a generation that believes that variability was very limited until Man caused a sudden uptick through increased co2 concentration.. That generation includes politicians who are, as a consequence of the past viewpoints and science, now making far reaching decisions that affect us all.
I’m not a politician and think the debate has become much too politicised and too acrimonious but if we were able to rewind to 1998 and start from the basis that the evidence still suggested a gently rising trend for hundreds of years with some notable upticks and downturns and not a gently decling trend for a thousand years with one recent dramatic uptick, I suspect the political decisions would have been different. We also might have been able to examine the reasons for the trend (and the one that seemed to have occurred from around 850 to 1250 or so) and not fixate on just co2. My concerns are that IF the climate should turn down again we have no ‘plan B’ to cater for it as we are so convinced that the Plan A to cope with a warmer world is all we need.
Lambs graph and the hockey stick were an interesting and useful general representation but we know a lot more now and can finesse their work and adjust it to suit what we have learnt. The trouble is that the latter still has considerable resonance and it contnues to cloud the debate.
Tonyb
Continuing ter ‘cloud the debate,’ yes Tony, the models sure have trouble with them pesky clouds. To quote from a denizen at Judith Curry:
‘I think I’ve never heard so loud
The quiet message in a cloud.’
H/t Kim.
Reblogged this on acckkii and commented:
Periodic warming is true. For floods there periods of 10 to 100 years periods with different magnitudes.
Lambs graph and the hockey stick were an interesting and useful general representation but we know a lot more now and can finesse their work and adjust it to suit what we have learnt. The trouble is that the latter still has considerable resonance and it contnues to cloud the debate.
Tonyb
Agreed. The hockey stick is over ten years old now and a lot of extra data has come in since then.
Look at Figure 1 here.
http://www.worldclimatereport.com/index.php/2005/03/03/hockey-stick-1998-2005-rip/
The error bars after 1600 are fairly small. Before 1600 they are much larger, and could encompass a significant warming or cooling trend.
Part of the problem now is that it has become contentious. The sceptics attack it and, almost by reflex, the consensus defends it.Both inflate its relative importance once you move beyond the last 130 years.
It has assumed an excessive importance as an icon, rather than an analysis.
entropic man
Yes, almost by conditioned reflex people attack or defend the stick, but its continuing importance remains as a symbol of what Mann is supposed to have done and it is difficult to move on and find out the truth behind it
tonyb.
Tony, thanks for your historical perspective. In the Sept/Oct issue of Archaeology Magazine, in an article on the LIA in Iceland, Mann is quoted as saying a volcano near the equator erupted in 1258, sending the temperature down 2-2.5°C (3-4.6°F). If one inserts this information into the the HS, it rather disrupts the fantasy of a stable past, and makes the current warming, well rather small, since we have had to recover those two degrees already, prior to the current warm period. http://i48.tinypic.com/2qlxtkz.jpg
Steve
Thanks for that. That is the exact period I am currently studying in order to extend CET further although the error bands will become much wider. I have looked at original scrolls from the 12/13/14th century and the various translations. These few snippets from such places as the library of Medieval Exeter Cathedral might be of interest
——– —–
1228-30 it ‘rained non stop’
Ad1230 the harvests having failed for two successive years, owing to continual rain which caused great overflowing of the river there was so great a scarcity of provisions that the people were obliged to eat horse flesh and to substitute bark of trees for bread
AD 1286 the summer proved very wet which caused great inundation-
‘The winter period was defined as the beginning of November to the end of the 11th or 12th weeks of the Christmas term-so winter lasted up to 20 weeks (note subsequent change of calendar) During this period (1279 to 1353) ‘the work force was much reduced in number on account of the weather, (in the winter) though work does not seem to have ever altogether ceased on this account.’
—- —-
To date I haven’t found any observational evidence of the 1258 volcano although there is a great deal of talk about its effects.
tonyb
Tony, here is a bit more information, as A.M. makes no footnote reference for what they are quoting from. This was proposed as the paper the reference came from:
Mann, M. E., M. A. Cane, S. E. Zebiak, and A. Clement (2005), Volcanic and solar forcing of the tropical Pacific over the past 1000 years, J. Clim., 18(3), 447–456