Up down all around it ends where it beginsRichard Treadgold | April 25, 2010
Most people take for granted that New Zealand’s surface air temperatures (SAT) have gone up over the last century. But is that true?
NIWA’s official graph of the national temperatures is well known. You can get it from their web site. By the way, if you go there, let me know if you think they’ve recently stretched the image laterally; it is definitely wider than before — even the text is obviously stretched sideways. Could they be trying to make the vertical change less prominent and thus reduce the apparent slope of the trend line? What goes through their minds at NIWA? Anyway, as copied a few months ago, and so a little different, it looks like this:
You should be aware that the Climate Conversation Group and the NZCSC have delivered a rip-snorting criticism of this graph, so we don’t agree with it even for a moment. Now I will raise further objections to NIWA’s graph because it contains features inconsistent even with NIWA’s own conclusions.
The first thing to check is the country’s average temperature in the 1860s. There is good material on this in the National Library. It turns out that in 1867 the New Zealand Institute recorded what was happening with the temperature. How convenient.
The new Dominion had already been recording temperatures in the main centres for about 15 years. So by 1867 the Inspector of Meteorological Stations could report that the average mean temperature to 1867 was 55.6°F — or 13.1°C. That was measured over about 15 years — giving a fair picture of the climate.
So how does it compare with today’s temperature? We shouldn’t take just a single year, for by carefully choosing the start and end points you will “discover” warming or cooling at will; it’s called cherry-picking and scientists frown on it but more importantly, you don’t discover the truth. Still, let’s take a brief look at recent annual temperatures for the sake of a human comparison: what did those pioneers actually experience?
NIWA’s web site has Climate Summaries for recent years giving various climatic information. For 2005, the national average temperature was 13.1°C. Last year, 2009, it was 12.3°C, nearly a degree lower than 2005. So in the 1860s it was 13.1°C, then, in 2005, after 138 years, the temperature was just the same. Last year it was slightly below 1867, at 12.3°C.
So our forefathers experienced the same temperatures we’ve been having recently!
Now compare the recent 30-year average of 12.5°C with the average from the 1860s of 13.1°C. It’s not very different: the temperature has moved down by only 0.6°C. That’s outside the likely margin of error (probably around 2°C) which means there’s no real change.
So those official records, pioneering and modern, show no warming, but actually a slight cooling.
But wait, there’s more. Look at NIWA’s official graph. Observe the decline into the first decade of the 20th Century, followed by a rise to about 1950. Finally, observe there is no significant trend since 1950. This graph highlights the period I’m talking about:
For the last 60 years the temperature shows no trend, so all of the rise — not just some of it, but all of it — claimed by NIWA, about 1°C, occurred before 1950.
It doesn’t look as though carbon dioxide dominates the temperature of the world’s climate, since while most of the CO2 was being emitted the temperatures didn’t go up. Because New Zealand sits in the world’s greatest ocean it’s a good proxy for global warming; the fact our temperatures have been pretty stable for 60 years says a lot about the globe’s temperatures.
Remember, I disagree with the facts this graph purports to show, but it’s still the official NIWA graph. Assuming it’s correct, it contradicts what NIWA themselves conclude. They say New Zealand (with the world) has been warming under the influence of mankind’s emissions of carbon dioxide. NIWA
manufactured uses this graph in support of this contention — in fact, it’s the only evidence they offer.
Yet it shows clearly that there has been no warming in New Zealand for the last 60 years.
This is laughable. What more evidence is needed to demonstrate NIWA’s incompetence?
It’s a disgrace.