Ever since the beginning of the greenhouse scare, astute observers have suspected that urban heat was responsible for a large slice of the purported warming. The IPCC has stonewalled, telling policymakers that the urban heat island issue has "...been taken account of." This site proves the contrary. There is simply no systematic compensation for urban warming in the Jones dataset. Occasionally there is a slight adjustment in a record for a site change or other anomaly but the majority of records are used “raw”. This applies even to large cities with large, documented heat islands – e.g. Los Angeles, Chicago, Sydney, Johannesburg etc. etc. In recent years, two independent remote sensing methods – nightlight pictures and infrared heat imaging – have clarified the extent of urban heat islands. Their evidence is incontrovertible. Nightlight images show that the bulk of CRU’s records come from lit areas of the surface. Infrared imaging shows that many are from cities with huge heat islands – enough to raise the annual average temperature by 2-3 degrees Celsius compared to the surrounding countryside.
The problem should have been obvious all along. The UHI was first identified in London 200 years ago, and many studies have shown that it can raise the temperature even in small towns. But political correctness, a desire not to "rock the boat", the corrupting influence of "greenhouse funding" on the science and sheer wishful thinking have made the urban heat island a tabu subject in the greenhouse debate.This site breaks that tabu. It turns the spotlight on individual city records included in the CRU dataset, and also examines the CRU results for various "grid cells" across the globe. It leaves no doubt that the CRU temperature graphs are contaminated with pervasive and substantial urban heat which has nothing to do with greenhouse gases. Satellite images of night lights have been published by NASA and give a good indication of the location of urban areas over the entire earth. Taking the same midwest USA area as the Infra Red image above, this is a small preview of how the Jones / IPCC temperature stations are dominantly located in urban regions.
The IPCC tell policymakers that the urban heat island issue has "...been taken account of.." Sure, we can see that, their data is collected mainly from UHI areas. Follow the Earthlights link for larger images of the USA with Jones stations located. See "City reviews" link at left for UHI contamination in Chicago compared to more rural neighboring stations. Below is a classic example of century long growth in small town UHI contamination from the region shown above: