I saw Al’s climate sci-fi movie, but I didn’t read the book. Via Tom Nelson, Robert Johnston has a refutation of some of Al’s claims in his book. This one caught my eye because it is a topic with which I am pretty familiar. Gore writes:
"People who want to deny global warming because it’s easier than dealing with it try to argue that what scientists are really observing is just the ‘urban heat island’ effect… This is simply wrong. Temperature measurements are generally taken in parks, which are actually cool areas within the urban heat islands… Most scientific research shows that ‘urban heat islands’ have a negligible effect…" (p. 318)
I can’t believe we let Al Gore lecture us on science. A few responses:
I don’t think most skeptics deny that some warming has occurred in the 20th century. Satellite measurement, which is not subject to urban heat island biases, has shown several tenths of a degree C warming since the late 1970’s. However, skeptics do tend to argue that surface temperature networks do tend to overestimate the 20th century warming signal due in part to urban biases (not to mention over-zealous addition of fudge-factors by the alarmists running the data gathering). Of course, we also will dispute that "most" of this warming is due to anthropogenic CO2.
The statement that most temperature measurements are taken in parks is so wrong as to be absurd. As Anthony Watts SurfaceStations.org climate station survey process has shown, the vast majority of stations are actually located near buildings (a predictable result of siting and cable length limitations of the most commonly used sensors). You don’t have to take my word for it, just scan the pictures yourself at random. I have had a lot of fun participating in this project. Here, by the way, is the Tucson station I surveyed. As you can see, the station is definitely located in a park[ing lot].
- We skeptics are often called "deniers" for not accepting that the theory of catastrophic man-made global warming is settled science. But if you want to see real denialism in the face of facts, one only has to look at the alarmist’s absurd position that, as Al Gore puts it, "urban heat islands have a negligible effect." The fact is that urban heat islands are well-known to science, and can cause the center of cities to be as high as 5-8C hotter than the outlying rural areas. It turns out that this is so horribly difficult to understand and prove that … my 14-year-old son did it for a science project. Here is the results of one of our data runs across town (details described in the article).
- Defenders of the surface temperature record will sometimes argue that they have successfully corrected for urban biases (leading to the cognitive dissonance of their saying that the biases have no effect and that they have fully corrected for them). But here is the problem: without detailed siting information, and surveys like that run by my son, it is impossible to make these corrections anything but guesses (ironically, many of the folks making this argument have opposed Anthony Watt’s survey process and continue to maintain that they can make better adjustments blind than having data of station siting). At most, the total warming signal we are trying to identify over the last century is about a degree F. But as you can see above, we found a 6 degree urban heat effect on the first night of our study, and we found a 9 degree urban effect our second night. You can see that not only does the magnitude of this heat island effect swamp the signal we are trying to measure, even the variability or uncertainty in assessing the urban bias is several times larger than the warming signal.
Update: Here is a new study debunking Gore’s claim that man-made global warming was melting the Kilimanjaro ice cap. This claim never made much sense, since even if temperatures were to warm by several degrees, they would still remain well below freezing all year long.