Posted by Jeff Id on November 5, 2009
Guest post by Tony Brown investigating the longest temperature records. Tony has put together a well referenced post containing an interactive graphic which allows clicking on a location to see the individual records. WordPress free version won’t allow it to function so check out the link. I think you’ll find it interesting.
contains some 50 Instrumental temperature records that precede the 1850 Hadley Global temperature information. (Just press on a red dot on the globe) There will be a well referenced study behind it in due course to put this information into perspective. It will hopefully become an invaluable resource for all researchers of climate.
These records provide a wealth of historic climate data for much of the Northern Hemisphere during a significant portion of the Little Ice Age. The datasets not only chart the considerable temperature variations through the centuries but also reflect the growth of the places they are located in, as many of the locations have developed from small towns in the 17th Century to large cities today.
I am currently looking for any more long data sets so this facility can be enhanced. Uccle (Belgium), St Petersburg and Lima (Peru) will be added shortly. I am looking for Cadiz/San Fernando and any others not already mentioned here. The criteria are pre 1850,–which can be slipped ten years if it covers an area not already well represented.
The comprehensive study will tell much more, but after sifting through vast amounts of information and corresponding with a wide range of sources I would like to make a few interim observations.
There appear to be a herd of very large elephants in the climate room that are apparently completely invisible. The first is one called ‘global temperatures to 1850’ that has a cousin ‘1880’.
These global datasets are astonishingly complex, based on very small numbers of stations which continually change, and appear to be mainly a record of the 0.2% of the globe that has become urbanised, rather than represent the 99.8% of the world that isn’t. Therefore these creatures are to be treated with the utmost caution.
The next elephant is one called UHI. Many people seem to spend a lot of time looking the other way when UHI rampages by, including the IPCC.
This was the IPCC take on the urban heat island effect (UHI) in 2001 which hasn’t materially changed in SPM 2007, page.5:
Clearly, the urban heat island effect is a real climate change in urban areas, but is not representative of larger areas. Extensive tests have shown that the urban heat island effects are no more than about 0.05°C up to 1990 (from 1900) in the global temperature records used in this chapter to depict climate change. Thus we have assumed an uncertainty of zero in global land-surface air temperature in 1900 due to urbanisation, linearly increasing to 0.06°C (two standard deviations 0.12°C) in 2000.
Real Climate also seems to be wearing their invisibility glasses and is as equally dismissive as the IPCC. http://www.realclimate.org/wiki/index.php?title=Instrumental_Record_is_Not_Reliable
The Urban Heat Island Effect has been examined quite thoroughly and simply found to have a negligible effect on temperature trends. Real Climate has a detailed discussion of this here. What’s more, NASA GISS takes explicit steps in their analysis to remove any such spurious signal by normalizing urban station data trends to the surrounding rural stations. It is a real phenomenon, but it is one climate scientists are well aware of and have taken any required steps to remove its influence from the raw data.
“The evidence points to a warming of about 0.6-0.8°C over the past century and a neglible effect on this from the UHI. While some ‘contrarians’ appear determined not to accept this finding, the evidence they cite appears thin indeed compared with the published research.”
World population has surged from 1.5 billion in 1900 to 6 billion now, for the first time in human history over half the population now live in cities According to the UN, the number of urban dwellers is expected to increase from roughly 3.2 billion today to more than 4.9 billion by 2030. Total area extent of the Earth’s urban land is said to be from 0.27 to 3.52 million km2 .Whilst Urban areas may therefore represent a small fraction of the globe it represents an increasingly large percentage of the instrumental global dataset.
Uhi has a disproptionately noticeable effect on those many stations that may have started off in a field hundreds of years ago, but are now in a green space hemmed in by buildings –these are very well represented in the pre 1850 datasets assembled in the graphic. (This link gives statistical data on population for each country/town going back hundreds of years) www.populstat.info
The UHI effect was noted as far back as Ancient Rome. At 1.5 million this was a huge city by the standards of the time From statements by Pliny the Elder and entreaties to Nero to ‘provide narrow streets with high houses to provide shade’ the Ancient Romans were fully aware of the UHI effect, designed their city accordingly, and there are many records of the great and the good leaving it for the cool of the surrounding country in the summer.
According to this report “Even normal Greeks and Roman bought snow and ice imported on donkey trains. Few could afford private ice houses. Most urban residents bought it at snow shops. In Rome deep pits were filled with snow and covered with straw. Water melted and ran through forming a bottom layer of ice that sold at a premium. Snow could be more expensive than wine.”
It seems we haven’t learnt too much over the last two thousand years. UHI needs to be taken much more into account in that large proportion of urbanised stations in the global record, as the current adjustment appears much too small. Whilst Uhi is undoubtedly real, after reading some 30 studies I feel its effects can be exaggerated (other than on still clear nights)
City design, wind, land use and the siting of a thermometer– amongst many other factors– will have an impact on the degree of UHI to be applied. However, there is surely a practical limit as to how much a thermometer can be affected by UHI-heat will tend to be dispersed over a wider area as the urbanisation grows, not necessarily become more concentrated. Consequently I think this graph and calculation that follows seems pretty close to reality, albeit that high latitude countries are likely to show greater daily and seasonal temperature variability than is noted here, so a degree could probably be taken off the figures. However the logarithmic curve seems to be a more sensible representation of the effect of urbanisation on temperature than some other studies.
As temperature stations have moved (many to to airports) or are in locations which bear no relation to their original untainted position, so clearly the historic allowance for uhi-virtually zero- must be questioned. In this regards it is very difficult to support the offical position of the IPCC and Real climate that UHI is to all intents neglible on global datasets, as that includes so many urbanised stations.
The next Elephant–probably the largest and sleekest– is that called ‘natural variability.’ It is represented by the following quotes.
1 IPCC FAQ 6.2 Page114 of TAR4.
‘All published reconstructions find that temperatures were warm during medieval times, cooled to low values in the 16th 17th 18th 19th centuries, then warmed rapidly after that.’
2) The UK Met office-a prime contributor through the Hadley centre to the IPCC assessments, assert:
Extract “Before the twentieth century, when man-made greenhouse gas emissions really took off, there was an underlying stability to global climate. The temperature varied from year to year, or decade to decade, but stayed within a certain range and averaged out to an approximately steady level.”
There is a great deal of evidence for considerable natural variabilty throughout our history, instrumental, written and observed. Commencing a data set at the depths of the last gasp of the Little Ice age (Giss/HadleyCru from 1850/1880) is all very well, but that there should be astonishment that temperatures have risen since ignores the undeniable fact that the current warm era is just one of the summits in a never ending series of peaks and troughs.
This excellent graph demonstrates the surprising variability of the LIA and its frequent warm periods. To paraphrase Dr Michael Mann the LIA is an outdated concept.
A cut off point of 1880 (Giss) or 1850 (Hadley/Cru) disguises the natural variability, as can be seen in two of numerous examples that can be observed in the ‘ Little Ice age Thermometers’ graphics-amply backed up by observations made at the time.
Giss global sets the scene for the familiar hockey stick
Which is broadly confirmed by Giss from 1880-Hohenpeissenberg Germany
However this data goes back to 1781 for the same station
It demonstrates that the escalating figure from the 1880 set is matched by a similar rise a hundred years previously and there are a very clear series of rises and falls
The second example also highlights that a start date of 1880 misses out on significant periods of climatic variability, but one which the Hadley set from 1850 catches. They come from two Swedish cities close to each other
This from Stockholm;
This from Arrhenius’ home town of Uppsala dated 1722-2005
There was great excitement in Stockholm recently concerning rising temperatures to ‘unprecedented’ levels, but a glance at the Uppsala chart demonstrates a warmer period just prior to the commencement of the Stockholm records (Both cities have had considerable study confirming a very real uhi factor) Consequently the Met office and IPCC assertion cited above is contradicted by numerous pieces of evidence.
* There appears to be an urgent need to carry out a comprehensive and independent audit of the global temperature records to 1850/1880.
* There needs to be a reappraisal of the undoubted natural variability of the climate that puts our modern experience into its proper context.
*The real effect of uhi on urban stations needs to be acknowledged.
*Someone, somewhere, needs to point out that a rise in temperatures from the low point of the little ice age is entirely to be expected and doesn’t warrant mass panic in the capitals of the world.
Therefore it seems appropriate that when the climate circus pitches up shortly in Copenhagen the descendants of Hans Christian Anderson-whose book ‘The Emperors New clothes’ was published in that city in 1837- will have the opportunity to point out the whole herd of apparently invisible elephants that is being ignored by a ring master who isn’t wearing any clothes.
Please let me know about any historic datasets pre 1850 you come across and please pay return visits to climatereason.com to watch the material develop.