A long-forgotten scientific paper on temperature trends in New Zealand may be the smoking gun on temperature manipulation worldwide.
Since Climategate first broke, we've seen scandal over temperature adjustments by NZ's National Institute of Water and Atmospheric research, NIWA, which in turn prompted a fresh look at raw temperature data from Darwin and elsewhere.
Now, a study published in the NZ Journal of Science back in 1980 reveals weather stations at the heart of NIWA's claims of massive warming were shown to be unreliable and untrustworthy by a senior Met Office climate scientist 30 years ago, long before global warming became a politically charged issue.
The story is published in tonight's TGIF Edition, and has international ramifications.
That's because the study's author, former Met Office Auckland director Jim Hessell, found a wide range of problems with Stevenson Screen temperature stations and similar types of unit.
Hessell debunked a claim that New Zealand was showing a 1C warming trend between 1940 and 1980, saying the sites showing the biggest increases were either urbanized and suffering from urban heat island effect, or they were faulty Stevenson Screen installations prone to showing hotter than normal temperatures because of their design and location.
One of the conclusions is that urbanized temperature stations are almost a waste of time in climate study:
"For the purpose of assessing climatic change, a 'rural' environment needs to be carefully defined. Climatic temperature trends can only be assessed from rural sites which have suffered no major transformations due to changes in shelter or urbanisation, or from sites for which the records have been made homogenous. Urban environments usually suffer continual modifications due to one cause or another."
"It is concluded that the warming trends in New Zealand previously claimed, are in doubt and that as has been found in Australia (Tucker 1975) no clear evidence for long term secular warming or cooling in Australasia over the last 50 years [1930-1980] exists as yet."
Hessell divided weather stations in New Zealand into two classes, "A" and "B", where A class locations had suffered increasing urbanization or significant site changes, and B class locations had not.
"It can be seen immediately that the average increase in mean temperatures at the A class stations is about five times that of the B class", the study notes.
Among the studies listed as a contaminated A site is Kelburn, which was at the heart of the NIWA scandal a fortnight ago.
A link to the study can be found in TGIF Edition.Other suggested reading: Air Con