Temperature Sensors, Heat Islands, and Global Warming

There is a volunteer project to check the placement of US temperature monitoring stations. This has found a number of stations that are improperly placed. NOAA guidelines call for the stations to be on grass, at least 100 feet from potential heat sources including pavement. Many of these stations are on pavement or gravel and some are near heat sources.

Al Gore's friends at RealClimate have an answer for this. Let's examine the issue.

First a note - I'm not positive that the RealClimate page I'm linking to was meant by them to be an answer to the problems with the monitoring stations but it was given as such in the comments section for my first link. Also, the first sentence at RealClimate refers to an assault on the measuring stations.

Before I begin I would like to point out that the problem with the stations is not the Urban Heat Island (UHI) Effect. RealClimate's first two points are spent "proving" that UHIs are taken into account. An UHI is caused by the accumulation of heat-absorbing surfaces found in urban areas. Parking lots and roofs absorb and radiate more heat than trees and grass.

All of that is irrelevant to the monitoring stations. A properly situated station will show warmer data than a rural one and that can be adjusted for (1) however a monitoring station that is located in a site warmer than the surrounding area will give false readings. A station placed in a field will show some warming from the surrounding area but one placed in the middle of a parking lot will be overwhelmed by the specific effects of the parking lot. This is also true of rural stations. If you place a station in the warmest spot within 1/4 mile then it will give false readings.

Yes, adjustments are made to urban readings to allow for the UHI effect but these adjustments are based on the the average of the UHI. If the station site is warmer than that then the adjustments will be insufficient.

RealClimate's 3rd poinis irrelevant. They point out that very little time is spent gathering the data so there is no time to validate the stations. This doesn't help their case.

Point #4 basically says that temperature measurement is really complicated so don't question it. This is refuted with the old acronym GIGO (Garbage In, Garbage Out). It doesn't matter how much you massage the inputs if the figures are wrong.

Now we get to the interesting part. Point number 5 points out that the glabal warming models are not connected to actual temperature measures so adjusting the measurements will not affect them at all. While this true, it will make it a lot harder to validate the models. If models do not reflect current temperature trends then why would we accept them in predicting the future. Not enough time is spent validating the models, anyway.

Their final point - that if only enough station data is thrown out then global warming will vanish has problems. Again, they fall back on the "it's really complicated" defense. They point out that only 60 well-placed stations would be enough but then they admit that the existing stations are not well-placed. They don't give any indication that the right 60 stations are being used. If a significant number of the existing stations are giving incorrect data then the redundancy in the system works against it. As a final "proof" they fall back on anecdotal evidence - receding glaciers, melting arctic waters, etc. This is a very poor defense since glaciers started melting before the CO2 build-up, antarctic ice is increasing, etc. Amazingly, while they admit to UHIs in their first point they never even consider its effect on early spring.

In short, RealClimate's defense amounts to saying that they know that global warming is real and there is nothing that you can do to shake their faith,

(1) Earlier this year it was discovered that the adjustments for UHI had not been made since 2000. That is why the temperature record was adjusted down for the last several years. This was discovered when one of the skeptics downloaded the raw figures in order to figure out exactly how these adjustments are made in the first place.