Court battle over degree of warming

A climate-sceptic group is taking Niwa to court over what it says are inaccurate temperature recordings.

The New Zealand Climate Education Trust - a branch of the NZ Climate Science Coalition - is challenging National Institute for Atmospheric and Water Research figures which show a temperature rise in New Zealand of 1 degree Celsius over the past 100 years.

This figure is significantly higher than global warming figures around the world and the trust is questioning how Niwa calculated the figures and whether they are accurate. It believes there has either been no warming or a trivial warming of around 0.2C.

The group's lawyer, Terry Sissons, told the High Court at Auckland yesterday that Niwa could have obtained inaccurate average temperatures due to "sudden site relocations" and by regularly changing temperature gauges.

“We're not saying that climatic changes are not happening but let's at least ensure the evidence gathered for the benefit of New Zealanders is accurate and is done properly," he said.

The case relates to information supplied on Niwa's website and, in particular, a graph called the "seven station series" which records New Zealand temperatures from 1853 to now.

In 2009, the trust released a document claiming the warming trend was a result of Niwa's in-house corrections and variations.

Fairfax Media