August 12, 2007, 1:14 am News

AUGUST  12,  2007


Dr Vincent Gray, Wellington, New Zealand

Environmental fanatics who had confidently predicted the coming ice age in the 1970s changed tack in the 1980s when the climate took the upward path of its regular 65-70 year oscillation, and revived the greenhouse gas warming theory which had failed so miserably in 1896 when Svante Arrhenius first predicted it. He was just on the wrong part of the cycle, as the temperature fell for the following fifteen years, and the two world wars took the attention away from those inclined to doomsday predictions.

The problem with the greenhouse theory, which confidently predicts a steady global temperature increase as a result of increases in the concentration of greenhouse gases in the atmosphere, is that this prediction is incapable of confirmation, because it is just not practically possible to obtain a reliable average temperature of the earth's surface.   

On June 23rd 1988 Dr James Hansen of the Goddard Institute of Space Studies, New York, told the US Senate that he had a solution to this problem. He proposed that global average temperature could be obtained from temperature records that had been taken at meteorological stations throughout the world, by assuming that these records could be considered characteristic of a large area of land territory (now 5ºx5º latitude/longitude boxes on the earth's surface) and if averaged, this could represent the average temperature of the earth, and any changes over time (anomalies) could represent changes in global average temperature

This procedure was welcomed without serious consideration of its limitations. These include

*No actual average temperature is ever measured anywhere. The early Met stations recorded only one measurement per day. The series now presented is dependent on a measurement of only two figures, the maximum and minimum temperature over  24 hours which is usually not identical to a normal day.

  • The stations are not randomly distributed, even over land. Stations are usually near cities or airports and the surroundings of the instruments change over the years, usually in such a way as to cause an increase. Some instruments are actually attached to buildings

*Very few stations remain in the same location over many years and the number of stations available has changed sharply over time.

  • Instruments and equipment are not standardized even within one country, and they change over time.

  • Supervision and calibration of equipment are also variable. In the USA, the measurements are made by "volunteers",  

  • This system applies only to the 29% of the earth's surface that is land, and only to a small part of that.

Very vigorous attempts have been made to try and correct the figures obtained, The most extensive have been in the contiguous United States, and when this is done, the resulting temperature record shows no evidence of influence of greenhouse gases, but, instead, a 65-70 year temperature oscillation

I attach the current record for the United States from Jim Hansen himself at

It is particularly topical, as he has recently corrected it for an error which now finds that the maximum temperature in the USA was in 1934 instead of 1998. He has been criticised for doing this correction surreptitiously.

A similar overall record for China also shows just the oscillation, but no global warming. I was given a paper that shows this during my visit to China last year

The correction applied in the United States relies on the presence there of many stations. These conditions do not apply in most countries, as Hansen admits in one of his papers, so the global record does not have the benefit of the corrections.

The land measurements are dubious enough, Sea surface measurements, for 71% of the earth, .are far more doubtful. as they are also poorly representative, are never in the same location, and the instruments and conditions of measurement highly variable. The contribution of heat from the ship itself is never considered,  Hansen has always refused to have anything to do with them, so the IPCC has  chosen the surface record of the University of East Anglia, which claims to have found a way to use sea surface measurements.

The influence of urbanization and  land and vegetation changes on the surface record is overwhelming, as I have summarized in my paper

Gray, V R 2000 "The Cause of Global Warming"  Energy and Environment  11  613-629

The IPCC, in the recent Fourth WGI Report, claimed that the urbanization effect is negligible on the basis of four scientific papers which they frequently quote.

The first was P D Jones, P Ya Groisman, M Coughlan, N Pl.ummer, W C Wang & T R Karl 1990. "Assessment of urbanization effects in time series of surface air temperature over land", Nature  347 169- 172.

Jones et al examined an "extensive" set of rural -station temperature data for three regions of the world; European parts of the Soviet Union, Western Australia and Eastern China. When combined with similar analyses for the contiguous United Sates, the results are representative of 20% of the land area of the Northern Hemisphere and 10% of the Southern Hemisphere

They worked out the linear slope of temperature anomalies for the rural series in each case and compared it with the same slope for several gridded series. For the Western USSR, this was 1901-1987, and 1930-1987, for Eastern Australia it was 1930-1988 compared with 1930-1997, for Eastern China it was 1954-1983, and for the contiguous United States it was 1901-1984 The differences were only significant at the 5% level for Eastern Australia and one set of Eastern China

They concluded "It is unlikely that the remaining unsampled areas of the developing countries in tropical climates, or other highly populated parts of Europe, could significantly increase the overall urban bias above 0.05ºC  during the twentieth century"

Although Jones et al. in subsequent publications,  have sometimes indicated that they apply this correction to their global series, it is unclear whether they have done so in the more recent publications.

There are several things wrong with this paper.

  • The quality of the data is even worse than usual, as they admit. " It is unfortunate that separate maximum and minimum temperature data are not more widely available"

  • The qualification for a "rural" site is a population below 10,000 for Western Soviet Union, below 35,000 for Eastern Australia, and below 100,000 for Eastern China. There is ample evidence (in my paper above to start with) that urban effects exist in such places.

  • They have chosen countries with a continuous record of effective scientific supervision. They are not representative of the rest of the world, where changes of country and adequate supervision are far less common

*Even these countries raise doubts. Russia had a tyrannical regime where statistics were frequently manipulated for political, purposes. China had a major famine from the "Great Leap Forward", and also a manipulation of statistics.

*Two of the countries, the contiguous USA and China, have such reliable records that, when corrected, they show no global warming, or residual urban influence. The United States cannot be regarded as "typical" of the world.

  • And here is the scandal. In the very same year that this paper appeared, 1990, there appeared in Geophysical Research Letters the following paper, which included two of the authors of the previous paper, Wei-Chyang Wang, and Thomas R Karl.

Wei-Chyang Wang, Zhaomei Zeng, Thomas R Karl 1990 "Urban Heat Islands in China"  Geophysical Research Letters,  17,  2377-2380.

The abstract reads as follows

"We used 1954-1983 surface temperature from 42 Chinese urban (average population 1.7 million) and rural (average population 150,000), station pairs to study the urban heat island effects. Despite the fact that the rural stations are not true rural stations, the magnitude of the heat islands was calculated to average 0.23ºC over the thirty year period, with a minimum value (0.19ºC) during the 1964-1973 decade and maximum (0.28ºC) during the most recent decades"

This study by two authors of the previous paper, appears to have used the same stations that were claimed to have no urban bias in the first paper, and now there is an urban bias even if "rural" now includes places with population as high as 150,000.

The early paper. Jones et al , states, of Eastern China

"The stations were selected on the basis of station history: we chose those with few, if any, changes in instrumentation, location or observation times"

Wang et al says

“They were chosen based on station histories, we chose those with few, if any, changes in instrumentation, location, or observation times"

It's as if both papers were written at the same time and different conclusions made from  the same data.

Recently Doug Keenan at

has shown that many of the Chinese stations moved several times over the period in question, in one case 15km.

Another crucial paper quoted by the IPCC to justify the absence of urbanization is

Thomas .C. Peterson 2000 "Assessment of Urban Versus Rural In Situ Surface Temperatures in the Contiguous United States: No Difference Found". Journal of Climate Vol 16 pages 2051 to 2959

Peterson studied only three years of data, 1989-91, so he was unable to study "trends" His excuse is rather startling.

"A longer period would increase the problem of missing data". The problem of missing data is not otherwise mentioned, but it  must very  be important if it has an influence after only three years in the USA.

He chose for study 40 clusters of stations, well distributed over the country; a total of 289 stations, 85 "rural", 191 "urban" and 13 "suburban.

The claim in the title "No Difference Found" is deliberately misleading. The overall urban/rural bias found was actually +0.31ºC, half the amount claimed by surface records to be caused by greenhouse gases since 1900.

He then "corrected" the data for elevation, latitude, instrumentation siting and time of observation. Differences in elevation accounted for -0.11ºC, because rural stations in the USA are usually higher up than the cities. Differences in instrumentation accounted for -0.05ºC, because rural stations had a higher proportion of hygrothermometers that had a warm bias over the period,, and latitude changes gave a negative bias, -0.06ºC. as urban stations tended to be a little further north than the rural stations.

The greatest of these corrections was "Time of Observation Bias". The "maximum/minimum" figure is taken at different times of the day in different places, and in each case refers to a different 24 hours; not a normal day. This bias was -0.17ºC.

When he had subtracted these various "adjustments" he was left with a bias due to urbanization of +0.04ºC. Although this is hardly negligible over only three years, Peterson considered it as "Not Found" because it was not significant at the 90% level. All he is saying is his sample was not big enough to give a significant figure for the urban bias. Perhaps it was "Not Found"; but the IPCC was not justified in treating the paper as evidence that an urban effect does not exist.

Yet another paper cited by the IPCC to discredit urban warming is the paper by David E Parker

"Large- scale warming is not urban" 2004,  Nature Vol 432 page 290 i

 This paper is so lightweight that it does not fill even a single page. It compares changes in minimum temperature records only for  "windy" and ""calm" nights for 264 stations since 1950 and finds very little difference Parker admits that coverage is only good north of  20º North plus Australia and that the timings of the minimum temperature readings were unknown, a factor which Peterson found to be very important .

Parker published a longer paper on the same theme at

"D E Parker 2006 "A Demonstration That Large Scale warming is not Urban" J of Climate 19  2882-2895.

 He seems to have discovered halfway through the paper, however, that the Maximum/Minimum temperature routinely measured at weather stations is for a different 24 hours from that which records wind intensity. He puts in a rather desperate Appendix A in which he wrote Emails all over the world to try and find out what happened locally. He showed no apparent influence of wind velocity, but is this really a measure of urban influence?

The inadequacies of these papers, as evidence for the absence of urban effects, shows that these effects are much more important as part of the surface temperature record than is admitted by the IPCC.

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