PaulL is adhering to good scientific approach here, folk knocking him for that do little other than display ignorance, and ‘faith-based’ argumentation, in cases introducing additional potential factors solely because his findings don’t fit with their ‘world view’ – I think that’s tragic – it certainly does nothing to promote their cause.

I look forward to further analysis, and perhaps rebuttal, from a scientific perspective, rather than what has been posted by his nay-sayers so far. I would also encourage PaulL to ask the questions of NIWA and|or Salinger.

My gut feeling is he’s on to something relevant – but that the effects will be ‘washed out’ by the averaging across sites. But my gut feeling is no more relevant than those who are dismissive of him.

In short, I’m somewhat disgusted by the faith-based dismissal of his findings, by those who would (presumably) argue that science is at the heart of the question. I am supremely disappointed that PaulL felt he had to set out his overarching opinions in order to ‘defend’ his data based research – and that I also felt that that would be ‘helpful’ at the outset – data is data, method is method, and the moment we start to analyse those based on an understanding or inference of an ‘agenda’, we do science a great disservice.

I didn’t ever claim that NZ hadn’t warmed, and I think it likely that NZ has warmed.

Having said that, if all the 7 stations used in that data set did have problems with their temperature record, then that would change the fact that NZ had warmed. Because this is measurement of fact – if you can’t measure it then it didn’t happen. I am open to changing my opinion based on the facts, you appear not to be. I’m not sure that is science, I think that is religion.

http://www.skepticalscience.com/urban-heat-island-effect.htm

My final comment on this NZ temperature record stuff: even if you could establish some significant UHI effect at Kelburn (unlikely), nothing changes the fact that New Zealand and the surrounding ocean areas have warmed, by the amount claimed. Still angels on a pinhead stuff, I’m afraid. Goodbye.

I started with a hypothesis, identified a way to test it, and the results from that test did not disprove the hypothesis. They didn’t prove it either, but I’m a bit stuck. I still think it is reasonable to expect a correlation between UHI and windspeed – that UHI would be less visible on windy days.

I don’t understand why we think wind direction, vegetation or any of the other concerns people have raised would be likely to affect the result, as I haven’t identified a plausible hypothesis for how those things would impact the result. I thought the scientific method required more than just a correlation, it also required a plausible method of causation. For the UHI effect, I have both a correlation and a plausible causation. For the other confounding factors that people have suggested, I don’t yet have any plausible way that they could be causing it. I’m not saying there isn’t a plausible way, just that nobody’s explained it. I’m tempted to believe that it is people just believing what they want to believe, and retrofitting the data to it.

PaulL, you can analyse away for a few years – then come back with the breathtaking discovery that Wellington, like everywhere else in NZ , has indeed warmed.

Meanwhile some small issues with your hypothesis: mean temperatures are “day-night” ie max/min averages, not daytime ones. The statement that windy “days” are colder than non-windy ones is a gross oversimplification and downright wrong in some contexts. It depends on the wind direction and the season as well, and of course on cloud cover/insolation. October 1988 was by far the windiest month in the recent Wellington records, with gusts to 63kph or more on 29 of the 31 days. It was also a warm month. The period from about 24 June – 17 July 2009 was notable for low windspeeds and very cold temperatures. For your further edification, windspeeds at Kelburn have been shown to be higher during daytime than at night, and higher in the warmer months than in cooler ones. Northerly flow is by far the dominant direction, at a ratio of about 2:1 over southerly.

I suppose any observed warming at Wellington Aero, that well-known wind tunnel, is also influenced by UHI? Not to mention Chateau Tongariro, Campbell Is etc?

RW, strange that you are so hostile to this analysis. It appears you are not trying to hide your bias. Paul seems to be making a genuine attempt to analyse the data and has not shown any bias thus far. He is open to critique and suggests. To attack him is absurd. Offer suggestions for improvement and if your hypothesis that there is no heat island contamination is correct the data will show that.

On wind speed, I’m trying to construct a scenario where the change in instruments results in a decrease in the measured warming only on the windy days. How about this hypothesis:
1. Windy days are colder than non-windy days
2. New measurement approach reduces the measured wind speed, bringing some days previously regarded as windy into the not-windy category
3. Since windy days are colder than average, bringing some windy days into the not-windy category results in cooling in the not-windy category
4. And since windier days are colder, those remaining in the windy category are colder than they were before

Problem for me here is that both the windy and not-windy categories should now show cooling, and only the windy category does.

I note Whaleoil’s latest post (I’m guessing not many of you frequent his blog ) with a photo of the Kelburn measurement site right next to the asphalt carpark. http://whaleoil.gotcha.co.nz/2009/12/07/climategate-niwa-got-some-splaining-to-do/

So whilst I give some credence to your hypothesis that changes in measurement approach have led to data that looks like UHI but isn’t, surely you’d equivalently have to concede that the big asphalt carpark next to the thermometer might give some UHI on windless days?

I also suggest a polite email to NIWA might help shed some light on your questions/data.

Regarding the 1 degree of temp rise, to me this doesn’t seem a big deal, for starters although global temp rise since 1930 is around 0.7 degrees (NASA GISTEMP record) there is significant regional variation in rates of warming.
Also the NIWA press release made it clear there has been a 0.7 degree rise in air temperatures over the ocean around NZ, since air temp over land increases faster than over oceans, this also suggests to me that 1 degree of rise sounds reasonable.

Also its not just models which show positive feedbacks (especially from water vapour). This is the area of climate sensitivity and there have been a large number of studies looking at the paleoclimate record to empirically calculate climate sensitivity.
The consensus is that positive feedbacks are real and the best estimate of a 3 degree rise for doubling of C02 remains unchanged.
If you can you could check out Annan & Hargreaves 2006, or Knutti & Hegerl 2008 for some recent papers on this.