Court action against New Zealand's state-owned weather and atmospheric research body is "stupid" and just creating confusion, University of Otago pro-vice chancellor of sciences Keith Hunter says.
The National Institute of Water and Atmospheric Research (Niwa) 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 Niwa's official temperature records.
The lobby of climate sceptics and the 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.
Coalition spokesman Bryan Leyland said many scientists believed although the earth had been warming for 150 years, it had not heated as much as 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 news media without permission.
But Prof Hunter told Radio New Zealand the courts could not determine whether or not the adjusted records had been adjusted properly.
"It can only be done by people who have an established scientific reputation in meteorology. So if the coalition has got those people they should do the analysis. If they haven't they should find someone else who has got that.
"There is nothing sinister about making adjustments. Measurements are often adjusted because of procedural differences between stations or changes in instruments with time.
"The coalition are just creating confusion. Throwing mud and if they throw enough mud some will stick and organisations like Niwa get dragged down in it," Prof Hunter said.
Meanwhile, the Environmental Defence Society (EDS) said in a statement that it may join court action in support of Niwa.
EDS chairman Gary Taylor said the society was evaluating whether there was merit in joining the proceedings.
"On the face of it, it's hard to see how the issue can properly be brought before the court. 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," Mr Taylor said.
The coalition will ask the court to find Niwa's New Zealand temperature record (NZTR) 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.
A substantive hearing was expected this year.