Before Salinger began his thesis, he had already written a 1975 article claiming that New Zealand temperatures were increasing. This was at a time when global temperatures had been decreasing for over 30 years, and the world’s news media were quivering with expectations of a new ice age. The young Salinger, who was not then engaged in climate science, thought the frequency of icebergs and the retreat of glaciers provided good clues.

After this 1975 article he visited CRU and began his student thesis, which broke new ground in suggesting ways to splice together the temperature readings for old and new measurement stations. Several methods were canvassed, but almost all of them seemed to reduce the actual readings at the old stations. So the temperature line moved up from old to new – lots of warming!

Now this seemed to be okay, because Salinger expected to find a warming trend anyway, because of the icebergs etc. It’s called “confirmation bias”.

These activities in the 1970′s were well ahead of their time. During the 1980′s the theory of anthropogenic global warming began to spread and the IPCC was set up in 1988. HadCRUT and GIStemp started assembling global instrumental records, and numerous peer-reviewed papers on adjustments to temperature records appeared during the 1990s and 2000s. None of these even mentioned the Salinger thesis.

On its website, NIWA boasts that it uses “internationally accepted techniques” for its adjustments. Clearly, it does not. The New Zealand Temperature Record was constructed using methods suggested in a 30-year old student’s thesis (which happen to produce warming trends) and has never been upgraded since.