Scibloggers are all tweeting furiously about this article on the Skeptoid blog. It's a pretty interesting piece, which argues that sceptics should follow the data and warmists should be nicer. There's much to agree with, but the author Craig Good rather shoots himself in the foot by repeated recommending Skeptical Science as an unbiased source on the subject of global warming.
As I have pointed out in the past, Skeptical Science's reporting of some issues I am familiar with are deeply troubling. It is hard to credit the site's failure to even mention that the Hide the Decline dataset had been truncated or to cover the troubled Cook et al divergence problem paper from 2004, but not the more up to date D'Arrigo et al study.
But hey, perhaps this is a one-off oversight. Maybe things are more balanced elsewhere in the Skeptical Science oeuvre. With this in mind, I went to have a look at the temperature records - thinking to see how the the subject of statistical significance was handled. I didn't find anything on a brief search but got distracted by this bit about urban heat islands - the bit of the observed warming that is due to waste heat from human settlements rather than climatic change.
[NASA/GISS] found in most cases, urban warming was small and fell within uncertainty ranges. Surprisingly, 42% of city trends are cooler relative to their country surroundings as weather stations are often sited in cool islands (a park within the city).
Now again, this is something I am reasonably familiar with. The claim comes from a paper by Peterson et al 2003 - having found that many urban stations warmed less than rural ones, they rationalised this by hypothesising that urban stations were in cool parks:
But do the urban meteorological observing stations tend to be located in parks or gardens? The official National Weather Service guidelines for nonairport stations state that an observing shelter should be ‘‘no closer that four times the height of any obstruction (tree, fence, building, etc.)’’ and ‘‘it should be at least 100 feet from any paved or concrete surface’’ (Observing Systems Branch 1989). If a station meets these guidelines or even if any attempt to come close to these guidelines was made, it is clear that a station would be far more likely to be located in a park cool island than an industrial hot spot.
And that's it. But, as we know, Anthony Watts has surveyed US weather stations and found that they are not even close to being compliant with the guidelines, a finding which makes a mockery of the claims in the Peterson paper, even leaving aside some of the other problems with the paper.
Don't get me wrong here. I doubt very much whether a properly calculated UHI correction would make a significant difference to the warming trend observed in recent decades. My point is not that you can pin a large number of the size of the UHI effect, but that you can pin quite a small one on the reliability of Skeptical Science.