A court has been told a hearing into the validity of the National Institute of Water and Atmospheric Research's (NIWA) official temperature records is not about denying climate change.
Proceedings brought by the New Zealand Climate Science Coalition got underway in the High Court at Auckland on Monday.
The coalition says the methodology used by the Crown institute to reach some figures is flawed.
It is asking the court to invalidate New Zealand's official temperature record, maintained by NIWA, and prevent it from using the current records to provide advice to the Government.
The coalition's lawyer has told the court the case was brought by a group of concerned individuals who are questioning the scientific method NIWA uses to measure temperature trends.
Radio New Zealand's reporter at the hearing says essentially the coalition is claiming that NIWA made adjustments to all records pre-1975 which skewed more recent data.
It also alleges bias and unethical conduct on the part of NIWA's National Climate Centre.
It says New Zealand has not heated as much as figures from Government archives show.
The hearing is set down for five days.