The Jones et al 1990 Letter to Nature: a rebuttal of some key points
Jones PD, Groisman PYa, Coughlan M, Plummer N, Wangl WC, Karl TR (1990) Assessment of urbanization effects in time series of surface air temperatures over land. Nature 347:169-172      [Click links in table  for scanned pages]
Page 169
Page 170
Page 171
Page 172

What does the letter say and why is it still important?

This 1990 Letter presents three regional temperature time series (all termed “rural”) built from weather station records that in general excluded large cities.  It compares the results of these three series with the Jones et al 1986 gridded series.  An observed similarity in the trends of the two sets is then taken as evidence that the gridded series contained negligible urban heat island (UHI) influence. 

The Letter was still quoted by the IPCC in its 2001 Third Assessment Report (TAR) as one of the two pillars of the claim by Jones, his supporters and the IPCC itself that any remaining UHI contamination in long-term temperature series is mimimal:

“These results confirm the conclusions of Jones et al. (1990) and Easterling et al. (1997) that urban effects on 20th century globally and hemispherically averaged land air temperature time-series do not exceed about 0.05°C over the period 1900 to 1990 (assumed here to represent one standard error in the assessed non-urban trends).”

The other pillar of the IPCC position, the Easterling et al. paper from 1997, has serious flaws, see here:  So unless the Jones letter is sound, the IPCC’s contention that urban warming does not exceed 0.05 degrees over the 20th century is unsubstantiated.

The Letter in context

It is fair to see the Jones et al. Letter as part of an attempt to deflect ongoing criticism that trends in Jones’ 1986 gridded data had a significant UHI component unrelated to greenhouse warming.  So it is likely there were mutterings of dissatisfaction in climate circles and by people who took the trouble to follow the debate in Wood 1988.  One example of this is the Australian Bureau of Meteorology (BoM) paper: Coughlan, Tapp and Kininmonth, 1990, "Trends in Australian Temperature Records" (which I have online at which estimated the magnitude of UHI contamination in Australian city data as follows:
"Estimates of the trends in the annual average daily mean temperature also indicated warming at most of the non-urban sites except Brisbane Airport. The strongest warming over the periods examined was 0.26 C decade~1 Mean temperatures at Brisbane Airport cooled by approximately 0.03 C decade 1. Trends in urban-rural differences were all positive.
These estimates are greater than those of the trends this century, reported by Jones et al. (1989), in annual mean Southern Hemisphere air temperature, over both land and sea, and sea surface temperature, which have all shown rises of approximately 0.06 C decade 1."

This paper and others circulating at the time (see note on Eastern Australia below) show that Jones et al had grossly underestimated UHI influence in their gridded series by failing to seek out true rural trends, and failing to understand that their so-called rural series  were in fact seriously contaminated by the UHI effect.

Jones et al.’s Letter to Nature attempted to contradict this by reference to supposedly rural series in three regions of the globe: Western Soviet Union, Eastern Australia and Eastern China.  The authors also referred to rural vs. urban trends in the 48 contiguous States of the USA.

Western USSR
Out of 38 stations in the Jones et al. rural series for this region, 9 were from towns circa 10,000 population, all 80+ kms from major cities, and the remaining 29 were from more remote sites.  We are currently trying to identify these 38 stations in order to verify the Jones et al claims.  However, note that regardless of whether the stations were truly rural, the results of this part of Jones et al’s analysis hardly support the “party line” of a maximum of 0.05 degrees UHI contamination over the whole twentieth century.  In fact, they find UHI contamination of at least 0.12 degrees in 57 years (1930-87) – equal to around 0.2 degrees per century, or four times the claimed maximum.  New page working through process of trying to identify all of the 38 rural stations.

Eastern Australia

The Letter also quotes an Eastern Australian series of 49 stations generated by Plummer of the Bureau of Meteorology (BoM) and others, for which the population averaged circa 5,775.  From 1991 onwards I had frequently warned the BoM and its staff that this series carried significant UHI contamination, and I circulated papers to them demonstrating this, e.g. "Heat Islands in SE Australian Country Towns".  But they steadfastly refused to see reality.

In the years to 1994 I worked on a big paper assembling the most rural series possible for Eastern Australia, bearing in mind the data shortcomings in records further from population centres.
East Australia temp trends 1930-92This paper, "Eastern Australia temperature variations 1930-1992" was co-authored with Dr Robert Balling Jr in 1994, submitted for publication in J Climate, and killed in review by someone in the BoM with IPCC connections. 

 "Eastern Australia temperature variations 1930-1992" is scanned online  and in my view it represents the most comprehensive attempt up to the mid-1990's to define truly rural trends over a significant area.  The table on  page 16 shows that the Jones et al 1986 . gridded series for the same region warms at 0.102 degrees per decade, just above Plummer and about double the true value if urban influences are rigorously excluded.

The figure on page 19 shows exactly how mean temperature (T) and daily temperature range (DTR) will typically vary for a regional array of station data classified by population.  The shape of these relationships was confirmed in a 2000 paper: Anthony Brazel, Nancy Selover, Russell Vose, Gordon Heisler: Clim Research Vol. 15: 123 135, "The tale of two climates Baltimore and Phoenix urban LTER sites" (see their   Figs 6 and 7 comparing T and population).

A similar gradation of UHI trends with increasing city population was depicted in Warwick S. Hughes and Robert C. Balling, Jr. "Urban Influences on South African Temperature Trends." International Journal of Climatology, Vol. 16, No. 8, pp. 935-940. See figure 3 here:  South African paper ;      Note also the large trend difference in our Figure 2 between our non-urban data (orange trendline) and the Jones 1994 gridded series.

The bottom line is that Jones’ Eastern Australia data  contains UHI effects amounting to ~0.05 degrees per decade – i.e. 0.5 degrees per century, or nearly ten times the rate claimed by the IPCC.

Eastern China 

For this large region Jones et al 1990 examines 42 station pairs of rural and urban sites but the "rural" stations had populations "…mostly less than 0.1 million…". 
New page outlining steps to discover the 84 stations in Jones et al 42 urban / rural pairs.
We are trying to identify these 84 stations in order to verify the Jones et al. claims, but it is obvious that a station with a population of anywhere near 100,000 can hardly provide a “rural” benchmark. An indication of the massive UHI influence in CRUT2 Sino grid cell data for the years 1979-2005 is given by comparison with MSU trends.

Results Table from Jones et al

The Letter also looks at UHI influences in the “lower 48” states of the USA.  Once again, Jones’ results contradict the de minimis estimate of 0.05 degrees per century UHI contamination, since his own estimate for this region is 0.18 degrees per century. 


It is remarkable that this paper is still listed in the IPCC 2001 TAR as backing the claim that UHI influence in Jones et al. gridded series is only ~0.05 degrees per century.  Considering the inadequacy of the only other reference the IPCC provides (Easterling 1997), its judgement on the scale of UHI contamination in long-term temperature aggregates is without serious foundation.

Back to Review comments on  climate papers by  key "IPCC Supportive"  scientists main page

There have been many posts at ClimateAudit on the subject of the Jones et al 1990 Letter to Nature in the first half of 2007  and most of these are linked or copied below, if there is no link then the date will get you in,  most recent on top.  Many of these posts touch on areas where work is still in progress.

April 29th, 2007
Queensland in Jones et al 1990
By Steve McIntyre

April 28th, 2007
Some Australian Station Plots
By Steve McIntyre

April 27th, 2007
Low Head and the Gnomes of Norwich
By Steve McIntyre

April 27th, 2007
The Maatsuyker Exclusion
By Steve McIntyre

April 25th, 2007
Phil Jones and Australian Billabongs
By Steve McIntyre

April 17th, 2007
CRU on Rural Data Exclusion
By Steve McIntyre

April 16th, 2007
Gridcell 47.5N 97.5E: Mongolia
By Steve McIntyre

Monday, April 16th, 2007 at 1:43 pm
Gridcell 42N, 112E Huhehaote
By Steve McIntyre

April 16th, 2007
CRU and Gridcell 27.5N 117.5E
By Steve McIntyre

Sunday, April 15th, 2007 at 8:56 pm
HadCRU3, GHCN and China
By Steve McIntyre

April 14th, 2007
Dulan Satellite Photo
By Steve McIntyre

April 14th, 2007
Jones et al 1990, TR055 and GHCN
By Steve McIntyre

Wednesday, April 11th, 2007 at 12:02 pm
Some China Comparisons
By Steve McIntyre

April 9th, 2007
Dulan Junipers and the Silk Road
By Steve McIntyre

April 3rd, 2007
Freedom of Information - Jones et al 1990
By Steve McIntyre

March 28th, 2007
IPCC and Data Access
By Steve McIntyre

Tuesday, March 13th, 2007 at 1:06 pm
Jones and the Great Leap Forward #2
By Steve McIntyre

March 12th, 2007
East Anglia Refusal Letter
By Steve McIntyre

March 9th, 2007
FOI Request to Phil Jones
By Steve McIntyre

Tuesday, March 6th, 2007 at 10:29 am
Barabinsk, Russia 57N, 77E
By Steve McIntyre

Friday, March 2nd, 2007 at 10:17 am
Reading Data
By Steve McIntyre

Friday, March 2nd, 2007 at 9:11 am
Gridcell 62N, 77E: Tarko-Sale, Russia
By Steve McIntyre

March 1st, 2007
Malye Karmakuly, Russia (#2)
By Steve McIntyre

Wednesday, February 28th, 2007 at 12:33 pm
Phil Jones and the Kazakh Copper Smelter (47N 67E)
By Steve McIntyre

Monday, February 26th, 2007 at 3:51 pm
Phil Jones and the Great Leap Forward
By Steve McIntyre

Sunday, February 25th, 2007 at 2:34 pm
Phil Jones and the Dutiful Comrades
By Steve McIntyre

February 17th, 2007
HadCRU3 versus GISS
By Steve McIntyre