The few stations that are left that are not biased because they are, for example, outside of town in a field and are an agricultural research station that's been around for 100 years. Their data gets completely swamped by the much larger set of biased data. There's no way you can adjust that out says Watts.
Roy Spencer agreed and added, “The surface thermometer data still have spurious warming effects due to the urban heat island which increases over time.” He also said, “Climate models used to drive changes in energy policy are even more faulty.” (2)
Spencer adds, “Warming of the global climate system over the past century has averaged 43 percent less than that produced by computerized climate models used to promote changes in energy policy. Contrary to media reports and environmental organizations' press releases, global warming offers no justification for carbon based regulation.”
Lt. Col. John Shewchuk, a certified consulting meteorologist, said the problems with temperature readings go beyond heat bias.”After seeing many reports about NOAA's adjustments to historical temperature data, I decided to download and analyze the data myself. I was able to confirm what others have found. It is obvious that overall, the past temperatures were cooled while the present temperatures were warmed.”
He contends that NOAA and NASA have adjusted historical temperature data in such a way as to make the past appear colder and by so doing, make the current warming trend more pronounced.(2)