Letters / Urban heat islands

There’s been an interesting development in the science of what causes the climate to change.

For many years scientists sceptical of the Intergovernmental Panel on Climate Change’s (IPCC) assertion that the only significant influence on climate is the level of atmospheric carbon dioxide have complained that global temperature trends produced by groups like the University of East Anglia Climate Research Unit (CRU),


the US National Oceanic and Atmospheric Administration (NOAA) and the US National Aeronautical and Space Administration (NASA) ignore the impact of poorly sited temperature measuring sites e.g. at airports and in city centres which, having expanded rapidly, can cause several degrees distortion in the temperatures measured.

Oddly, none of these organisations has studied the so-called “urban heat island” effect properly however others have now done it for them and Watts et al 2012 (Watts, Evans, McIntyre and Christy) have pre-released their paper in advance of formal publication to open it to the “widest possible peer review.” They are obviously confident their methodology is sound.


Watts et al’s findings compare the USA temperature trend measured using strict “Leroy” (proper scientific) siting criteria with the trend actually produced by NOAA and their conclusion is clear:

“These factors (upward adjustments of actual measurements – JT), combined with station siting issues, have led to a spurious doubling of U.S. mean temperature trends in the 30 year data period covered by the study from 1979 – 2008.”

A spurious doubling! Yes, NOAA has been saying the trend has been +0.309C/decade whereas the rigorously-produced new version suggests the true rate of rise is half of that, +0.155C/decade.

It’s not unreasonable to speculate that this result may be replicated for land measuring sites around the globe – the US, after all, is likely to have among the best siting criteria.

Well, well! Isn’t that exactly what all those vile “climate change deniers” have been saying all along?

“Chapter and verse” is available at http://wattsupwiththat.com/2012/07/29/press-release-2/

John Tulloch