Climate Conversation Group

NIWA (National Institute of Water and Atmospheric Research) has been accused of “propaganda posing as science” in its claim that the 2000s have been the warmest decade on record. The New Zealand Climate Science Coalition says the claim that the “noughties” decade is the warmest is based on a statistic for which the margin of error is far greater than the claimed warming.

The Coalition says it fully agrees with the criticism by Blue Skies weather forecaster Tony Trewinnard that NIWA’s own numbers show there is no long-term warming trend.

The warm decade claim is one of five by NIWA which amount to advocacy rather than science, and as such represents propaganda which should not be expected from a Crown research institute, especially one claiming to be based on science. The examples of advocacy are:

1) The warmest decade: NIWA principal climate scientist Dr James Renwick told newspapers that temperatures at seven key stations over the past 10 years were one-tenth of a degree above the 1971-2000 norm, adding “the next warmest were the 1980s, about 0.07°C above that normal, so it’s only a few hundredths of a degree difference”. Dr Renwick should know that a few hundredths of a degree is well inside the margin of error for temperature readings and is, therefore, meaningless. The Coalition says if Dr Renwick doesn’t know about margin for error he shouldn’t be in the job; and if he does know it, he has misled the public.

2) NIWA constantly claims that spot temperatures are just ‘noise’ and only long-term trends are important in climate science. NIWA’s statement notably fails to mention that the upward trend in the nineties has unexpectedly disappeared in the ‘noughties’.

3) Most of the warming in New Zealand occurred prior to about 1955, well before the build-up of atmospheric CO₂. There has been little or no statistically significant warming in New Zealand over the past 55 years. NIWA fails to put its information in its proper context.

4) Climate is always warming or cooling. There no evidence whatsoever that ‘climate change’ in New Zealand over the past 150 years is outside the expected range of normal climate system variability.

5) The NIWA press statement wrongly contended that 2009 was a year of warm weather extremes, when it is usually at pains to distinguish weather from climate. It dwelt on cyclones in the Pacific without mentioning the vanishing hurricanes in the Atlantic. It studiously avoided mention of the blizzards which disrupted the Copenhagen conference and are currently setting coldness records throughout the Northern Hemisphere. The entire piece is a classic example of the use of selective and misleading data.

The Coalition statement concludes: “Until NIWA responds to our request to come clean on the full extent of its adjustments to raw temperature data, exactly what adjustments were made, and why, any statement that institute makes about climate variation must be taken with a grain of salt.”