Fred Too

Information

Opinion

NIWA, the National Institute of Water and Atmospheric Research, is a Crown Research Institute that, amongst other things, looks after our national climate database. It releases regular climate publications including a monthly climate summary.

NIWA seems to take every chance it can to push the idea of worrying climate change. September 2022 wasn’t exactly a warm month but in their September 2022 climate summary, NIWA stated that it was 0.4°C above the 1981–2010 September average, making it New Zealand’s 19th-warmest September since NIWA’s seven station temperature series began in 1909.

When NIWA puts out its monthly climate summary it always compares the average temperature for the month against the 1981–2010 average for that month. Because the climate across New Zealand appears to have warmed a little since that thirty-year 1981–2010 period, NIWA can trumpet in nearly every single report that the month is x°C warmer than average.

Using that historical 30-year average as a comparison is misleading. Even if the gradual increase in temperatures were to grind to a halt, above-average temperatures will continue to be reported month after month.

I made the point to NIWA last year that using a historical thirty-year average as a comparator is misleading. They told me they intended to update the 1981–2010 average to make it a 1991–2020 average. I have inquired several times since about when the update is going to happen. Each time I have been told NIWA still intends to do the update but that it is a difficult exercise that other countries have also been struggling with.

If all the historic monthly averages were calculated correctly then it should be a relatively straightforward exercise to update the thirty-year average to end in 2020, like NIWA is promising. It is a simple mathematical exercise that shouldn’t take years of work to complete!

At one stage I tried to calculate a time series of how the monthly averages reported by NIWA compared to the average from the year before and the thirty-year average, but I started coming up with anomalies – nothing major but things weren’t consistent. It made me concerned that NIWA has been adjusting their temperature records.

So I suspect NIWA is having trouble updating its thirty-year temperature averages because the numbers have been fiddled with and are now difficult to reconcile. Or maybe they are just worried that updating the averages will mean their temperature reporting will not fit the narrative they want? It seems they want to report temperatures only in a way that implies average temperatures are continuing a relentless rise.

Maybe I am wrong, but there certainly seems to be something fishy going on at NIWA.

https://niwa.co.nz/climate/monthly/climate-summary-for-september-2022

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