Spencer shows compelling evidence of UHI in CRUTem3 data

I am only a fan of the climate debate and have no qualifications to perform an informed debate but could someone tell me why, when Hugh Pepper said “They concluded that, since only 0.5% of the world is urbanized, even a 2 degree rise in urban temperature would contribute negligibly to the global average.” he was roundly criticized for having missed the point that there are more stations, more thermometers in urbanized areas than rural.
Why should the density of thermometers per square kilometer make any difference whatsoever? Is a square kilometer with a dozen thermometers somehow warmer than the same area with one?

Henry says
The problem is that in the 99.5% where there is no people living, there are no thermometers. So all weather stations taken together are “skewed” to read the UHI effect, including some extra plantation of vegetation by man that is also contributing to the entrapment of heat, as explained earlier.
That is certainly an exaggeration. There are not “no thermometers”. There are less of them. However, you suggest that rural temperatures are being erroneously interpolated from urban thermometers. It is my understanding that limts are commonly used as to the distance across which temperature data are interpolated. That would seem to restrict the rural area to which urban readings would be applied.
I also wonder, if the global warming trend is simply the product of increasing urbanization:
1) Why did Peterson 2003 find so little UHI effect in general and Jones 2008 found no signal at all from increasing urbanization in China?
2) What is causing the increase in ocean heat content?
3) What is causing the dramatic air temperature increase in the Arctic?

Abraham3, in some data bases, Arctic air temperatures are actually not Arctic, they are land based. The grid over the Arctic is filled in with land temperatures. Other data bases use other methods. The various methods of filling in the Arctic grids make quite a difference in the final data shown to us, if you consider digits far to the right of the decimal point.
However, artifacts of method is not a significant contributor to real Arctic temperatures. Arctic Atmospheric Pressure Oscillation conditions and oceanic currents provide the lion’s share of temperature anomalies across the Arctic as it yearly cycles through the pattern of solar heating available to it. Anything else, be it method artifact, Sun anomalies, or CO2 increase- variables that only very slightly and only mathematically, not measurably- affects Arctic temperature is buried minutia.
Day to day Arctic temperature trends, thus statistical averages and year to year trends, are highly and significantly correlated to natural oceanic and atmospheric Arctic conditions. Period. In fact any trend in temperature anywhere in the world is also so correlated to the oceanic and atmospheric conditions there. And not a single AGW scientist or enthusiast can claim, show, or prove any different.

Climate change in the Arctic and Effects of global warming
(Wikipedia)
There are several reasons to expect that climate changes, from whatever cause, may be enhanced in the Arctic, relative to the mid-latitudes and tropics. First, is the ice-albedo feedback, whereby an initial warming causes snow and ice to melt, exposing darker surfaces that absorb more sunlight, leading to more warming. Second, because colder air holds less water vapour than warmer air, in the Arctic, a greater fraction of any increase in radiation absorbed by the surface goes directly into warming the atmosphere, whereas in the tropics, a greater fraction goes into evaporation. Third, because the Arctic temperature structure inhibits vertical air motions, the depth of the atmospheric layer that has to warm in order to cause warming of near-surface air is much shallower in the Arctic than in the tropics. Fourth, a reduction in sea-ice extent will lead to more energy being transferred from the warm ocean to the atmosphere, enhancing the warming. Finally, changes in atmospheric and oceanic circulation patterns caused by a global temperature change may cause more heat to be transferred to the Arctic, enhancing Arctic warming (ACIA 2004).
According to the Intergovernmental Panel on Climate Change (IPCC), “warming of the climate system is unequivocal”, and the global-mean temperature has increased by 0.6 to 0.9 °C (1.1 to 1.6 °F) over the last century. This report also states that “most of the observed increase in global average temperatures since the mid-20th century is very likely [greater than 90% chance] due to the observed increase in anthropogenic greenhouse gas concentrations.” The IPCC also indicate that, over the last 100 years, the annually averaged temperature in the Arctic has increased by almost twice as much as the global mean temperature has. In 2009, NASA reported that 45 percent or more of the observed warming in the Arctic since 1976 was likely a result of changes in tiny airborne particles called aerosols.
There was a period from the late 1920s to the early 1950s during which the Arctic was almost as warm as it is today, though the spatial pattern of today’s warming differs from that of the earlier period. Sea ice extent has decreased by 5.25% to 8.25% since 1979, the beginning of the reliable satellite record, with a larger decrease in summer (12.5% to 24.5%) than in winter (IPCC 2007).
Climate models predict that the temperature increase in the Arctic over the next century will continue to be about twice the global average temperature increase. By the end of the 21st century, the annual average temperature in the Arctic is predicted to increase by 2.8 to 7.8 °C (5.0 to 14.0 °F), with more warming in winter (4.3 to 11.4 °C; 7.7 to 20.5 °F) than in summer (IPCC 2007). Decreases in sea-ice extent and thickness are expected to continue over the next century, with some models predicting the Arctic Ocean will be free of sea ice in late summer by the mid to late part of the century (IPCC 2007).
A study published in the journal Science in September 2009 determined that temperatures in the Arctic are higher presently than they have been at any time in the previous 2,000 years.[2] Samples from ice cores, tree rings and lake sediments from 23 sites were used by the team, led by Darrell Kaufman of Northern Arizona University, to provide snapshots of the changing climate.[3] Geologists were able to track the summer Arctic temperatures as far back as the time of the Romans by studying natural signals in the landscape.[4] The results highlighted that for around 1,900 years temperatures steadily dropped, caused by precession of earth’s orbit that caused the planet to be slightly farther away from the sun during summer in the Northern Hemisphere.[2][3] These orbital changes led to a cold period known as the little ice age during the 17th, 18th and 19th centuries.[2][3] However, during the last 100 years temperatures have been rising, despite the fact that the continued changes in earth’s orbit would have driven further cooling.[2][3][5] The largest rises have occurred since 1950, with four of the five warmest decades in the last 2,000 years occurring between 1950 and 2000.[2] The last decade was the warmest in the record.[6]
1.^ 2009 Ends Warmest Decade on Record. NASA Earth Observatory Image of the Day, January 22, 2010.
2.^ a b c d e Kaufman, Bo M.; Schneider, David P.; McKay, Nicholas P.; Ammann, Caspar M.; Bradley, Raymond S.; Briffa, Keith R.; Miller, Gifford H.; Otto-Bliesner, Bette L. et al (2009). “Recent Warming Reverses Long-Term Arctic Cooling”. Science 325 (5945): 1236–1239. Bibcode 2009Sci…325.1236K. doi:10.1126/science.1173983. PMID 19729653.
3.^ a b c d “Arctic ‘warmest in 2000 years'”. BBC News. September 3, 2009. Retrieved September 5, 2009.
4.^ Derbyshire, David (2009-09-04). “Arctic ice reveals last decade was hottest in 2,000 years”. London: Daily Mail. Retrieved 2009-09-05.
5.^ Walsh, Bryan (2009-09-05). “Studies of the Arctic Suggest a Dire Situation”. Time. Retrieved 2009-09-05.
6.^ “Natural cooling trend reversed”. Financial Times. 2009-09-04. Retrieved 2009-09-04.

Parker’s wind studies did not rely on Wang’s data. And, to be fair, UEA gave the following response:
Statement from the University of East Anglia in response to ‘UK scientist hid climate data flaws’ (Guardian, 02.02.10)
Tue, 2 Feb 2010
The allegations made in today’s Guardian create a misleading picture and require important clarifications in three areas:
1. The FOI request was responded to in full
The FOI request from Douglas Keenan was responded to by the university in full in 2007. The data used in the 1990 paper were indeed sent to Mr Keenan, including both the locations of the stations and the station temperature data for China, Australia and western parts of the former Soviet Union. For China, the data covered the period 1954 to 1983. The data were also uploaded onto the Climatic Research Unit (CRU) website.
2. The accuracy of the data and results was confirmed in a later paper
Prof Jones embarked on a study in 2007 which was published in the Journal of Geophysical Research in 2008. In this later study, CRU researchers worked with a Chinese colleague (Dr Q. Li) from the China Meteorological Administration (CMA) in Beijing. Dr Li had been assessing the consistency of 728 Chinese temperature series and his work was published in China in 2007. This improved CMA data was adjusted to account for changes in location of stations.
CRU requested this improved CMA data for the stations that had been used in the 1990 study, and they were incorporated into the 2008 paper.
Figure 6 from this study (see below [not shown]) shows the comparisons (as anomalies from the 1954-1983 period) between the averages of the 42 rural and 42 urban sites used in 1990 compared with averages from the same stations from the CMA network. The dashed lines are the averages for the rural and urban sites in eastern China from the 1990 paper. The solid lines are the averages from the same stations from the CMA network. It is clear from the graph that the trends of the CMA data for both the rural and urban networks agree almost exactly with the results from the 1990 paper.
The 2008 study undertook additional analyses using more extensive data and did conclude that there was a likely urbanization trend in China of 0.1 degrees Celsius per decade for the period 1951-2004. But allowing for this, there was still a large-scale climatic warming of 0.15 degrees C per decade over the period 1951-2004 and 0.47 degrees C per decade over the period 1981-2004. The paper concluded that much of the urbanization trend was likely due to the rapid economic development in China since the 1980s, after the period analysed in the 1990 paper.
3. The CRU findings were corroborated by other papers used by the IPCC
The 1990 paper was only one of a number of papers referred to in the 2007 IPCC Report examining possible urbanizations effects.
References
Jones, P.D., Groisman, P.Ya., Coughlan, M., Plummer, N., Wang, W-C. and Karl, T.R., 1990: Assessment of urbanization effects in time series of surface air temperature over land. Nature 347, 169-172.
Jones, P.D., Lister, D.H. and Li, Q., 2008: Urbanization effects in large-scale temperature records, with an emphasis on China. J. Geophys. Res. 113, D16122, doi:10.1029/2008/JD009916.
Li Q. and W. Li, 2007: Development of the gridded historic temperature dataset over China during recent half century, Acta Meteroloigca Sinica, 65, 293-299 (In Chinese).

In case the point of my previous article wasn’t clear — it is stupid to try to infer the UHI effect from antique data, when one can just bloody well measure it directly and on purpose with a suitably designed experiment now, and to very high precision indeed. Anthony already took the first steps towards this when he documented the poor siting of many weather stations — the obvious and directly measurable conclusion is that those poorly sited stations almost invariably show more warming although all one has to do is look at patterns of snow-melt after a fall to realize that it is possible (but less likely) to site a station that stays significantly colder than “true ambient temperature” (whatever that means) as well.
This isn’t to criticize Roy’s efforts to do so (any more than I would criticize Jones et all, or any of the many others that have tried to do so) — it is just that this is a great big why do so when it is so easy to design an actual experiment to directly measure it and in the process contruct a fine-grained picture of spatial thermal variation as multivariate function that might actually permit inferences to made from the historical data the other way — if nothing else accurately characterizing the noise and bias associated with our ignorance of siting and the measurement process used for ancient historical thermometry. If there are degrees K of noise to be had in a 1/2 acre plot, and more degrees K of systematic noise to be had in a three mile circle, one has to deconvolve a complicated multivariate systematic bias function in order to statistically “correct” otherwise anonymous temperature readings (and those readings will end up with large error bars).
Why infer when you can measure? The same is true for the GHE — why infer it, model it, assume it, when the open desert provides one with ample opportunity to directly measure it in air with minimal confounding moisture?
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