The country's state-owned weather and atmospheric research body is being taken to court in a challenge over the accuracy of its data used to calculate global warming.
The New Zealand Climate Science Coalition said it had lodged papers with the High Court asking the court to invalidate the official temperatures record of the National Institute of Water and Atmospheric Research (Niwa).
The lobby of climate sceptics and Act Party have long criticised Niwa over its temperature data, which Niwa says is mainstream science and not controversial, and the raw data publicly available.
The coalition said the New Zealand Temperature Records (NZTR) were the historical base of NIWA's advice to the Government on issues relating to climate change.
Coalition spokesman Bryan Leyland said many scientists believed although the earth had been warming for 150 years, it had not heated as much as Government archives claimed.
He said the New Zealand Meteorological Service had shown no warming during the past century but Niwa had adjusted its records to show a warming trend of 1degC. The warming figure was high and almost 50 per cent above the global average, said Mr Leyland.
The coalition said the 1degC warming during the 20th century was based on adjustments taken by Niwa from a 1981 student thesis by then student Jim Salinger, a Niwa employee who was later sacked after talking to the media without permission.
The Salinger thesis was subjective and untested and meteorologists more senior to Dr Salinger did not consider the temperature data should be adjusted, it said.
The coalition would ask the court to find Niwa's New Zealand Temperature Record invalid.
It would also seek a court declaration preventing Niwa from using the NZTR when it advised the Government or any other body on global climate issues. It would also ask the court to order Niwa to produce a full and accurate NZTR.
Mr Leyland said Niwa was refusing to repudiate the NZTR to avoid political embarrassment and loss of public confidence.
A substantive hearing was expected later this year.
The Environmental Defence Society said the facts pointed toward global warming, and that humans were contributing to it.
"On the face of it, it's hard to see how the issue can properly be brought before the Court," said chairman Gary Taylor.
"We have no doubts that the science behind global warming predictions is robust and reliable and would wish to support the institute in any way that we can.
"It is one thing to have a robust debate about the science and quite another to attempt to belittle and undermine the need for action as the Coalition has been doing now for years."
- NZPA, NZHERALD STAFF