The more I look into the methodologies used to calculate “average” temperatures, the more I shake my head. Urban areas are hotter than rural ones. This is due to all sorts of things. From heat absorbing concrete and asphalt to air conditioners, there are plenty of things that give rise to the so called “urban heat island” effect. Over the past 100 years, many of the temperature stations in the US have been swallowed up by urbanization. One would assume that they would give us higher temperature readings than the stations in the country do.
All pretty logical, no? Well get this, the people at NASA that publish the most often used temperature data for climate change have a rather odd methodology. When they look at a specific geographical area, there are both urban and rural readings to choose from. One would think that the rural readings would be the more accurate. If they were to use the urban readings at all, you would think they would introduce a downward “correction” based on the rural readings. How much downward is certainly debatable, but the general direction it should go in isn’t in question. What do they do? They bias the rural readings upwards to come closer to the urban readings! I can’t think of a defense for this at all, assuming that accuracy is the goal of course… There are some glaring examples of this. The station in the Grand Canyon can be assumed to be an accurate reading location. There’s nothing there that could really screw things up. The Flagstaff location on the other hand is on an asphalt parking lot and is lined with air conditioning vents on one side. Not surprisingly, the Flagstaff station records significant;y higher temperatures. The Grand Canyon result is “corrected” upwards to come closer to the Flagstaff result. Unbelievable…
Not only is there weird things going on with individual stations, but entire periods of time have had a “correction” done to them. The early part of the 20th century was “corrected” downwards. In other words, the people at Nasa (Hanson cough cough) feel that the the stations during the early part of the century were giving us readings hotter than they should have and the stations now are giving us readings cooler than they should. What?! If anything, the opposite should be true, what mechanism would bias readings hotter back then? Urbanization can certainly help explain higher than expected readings at some stations, but not back then… Weirder and weirder.