A judge has reserved his decision about whether the National Institute of Water and Atmospheric Research used invalid methods to gather temperature data, as alleged by a group sceptical of global warming.
The New Zealand Climate Science Education Trust, a branch of the NZ Climate Science Coalition, brought a case against the country's state-owned weather and atmospheric research body before the High Court at Auckland this week.
It argued Niwa (National Institute of Water and Atmospheric Research) records, which show a national warming trend of almost one degree Celsius in the last century, are invalid and almost 50 per cent above the global average for the period.
The dispute relates to readings from the "Seven-station Series" (7SS) - stations in Auckland, Masterton, Wellington, Nelson, Hokitika, Lincoln and Dunedin - used by Niwa for national temperature records.
"We're not saying climate change doesn't exist. We're saying let's at least make sure that evidence of this for New Zealanders is accurate," trust lawyer Terry Sissons told the court earlier this week.
Niwa's lawyer Justin Smith argued that the science used to gather the data was sound and, nonetheless, court was not the place to settle such a debate.
Mr Smith said there was a well-known judicial reluctance to resolve scientific debate, which "affects the plaintiff's case in almost every aspect".
He also questioned the credibility of the evidence of two of the trust's "expert" witnesses.
Justice Geoffrey Venning reserved his decision.
