Here’s some great information about the perils of trying to measure temperatures accurately over a long time and the continued refusal of the media to ask questions on the GW topic. I encourage you to read the entire article.
Not So Hot By Patrick J. Michaels Published 12/27/2007 12:07:49 AM
If a scientific paper appeared in a major journal saying that the planet has warmed twice as much as previously thought, that would be front-page news in every major paper around the planet. But what would happen if a paper was published demonstrating that the planet may have warmed up only half as much as previously thought?Nothing. Earlier this month, Ross McKitrick from Canada’s University of Guelph and I published a manuscript in the Journal of Geophysical Research-Atmospheres saying precisely that.Scientists have known for years that temperature records can be contaminated by so-called “urban warming,” which results from the fact that long-term temperature histories tend to have originated at points of commerce. The bricks, buildings, and pavement of cities retain the heat of the day and impede the flow of ventilating winds.
For example, downtown Washington is warmer than nearby (and more rural) Dulles Airport. As government and services expand down the Dulles Access road, it, too, is beginning to warm compared to more rural sites to the west.
Adjusting data for this effect, or using only rural stations, the United Nations’ Intergovernmental Panel on Climate Change states with confidence that less than 10% of the observed warming in long-term climate histories is due to urbanization.
That’s a wonderful hypothesis, and Ross and I decided to test it.