The Narrative Fallacy in Weather

20 March, 2007

Looking back at my most recent posts on rainfall I note that they were motivated at a reaction to what Nassim Taleb describes as the Narrative Fallacy, the desire people have to make a post-hoc story to so all events relate with a strict cause and effect. Journalists (amongsts others) love to try and join dots and so are typical propagators of this nonsense. Recently they have been keen to link everything weather related like the drought, to global warming.

Should I worry about this though? Ultimately I think we should be acting to mitigate AGW, so is it best for us not to be criticising our “side”? I think that this kind of partisanship is amongst the worst things that can be done. Claims that are unsupported by evidence will ultimately undermine the very case they are trying to support. They are in effect crying wolf.

The stupidity of course isn’t limited to AGW alarmists, with many if not more of the skeptics running the its a cold day, it can’t be warming line. Some of these are taking the piss but not all of them. Some seem to believe its a refutation.

Ultimately it would do well if people were to remember that a particular instance is usually not a good representation of the average. Its ridiculous to ascribe meaning to every single occurrence, and even a couple of years don’t really do much to hundred year trends. Climate is long term average weather. Year to year it varies, and we are looking at long term trends not day to day heatwaves or even year to year droughts.


More on rainfall

15 March, 2007

For those unconvinced about my previous claim that, according to the BOM data, there doesn’t appear to be a drying trend on the east coast and think it might be an artifice of too broad averaging, I note that they should have a look at the trend maps found here. For example the rainfall trends from from 1900 to 2006.
Australian Rainfall trend 1900 - 2006

This shows few regions which have shown a definite drying trend over the period. One clear exception being the south west of WA, which does show a drying trend over pretty much anytime period you pick. In addition it appears that some slight trend could be evident in mid to northern Queensland.

Go and have a look at some of the different time periods on their site, the lack of a clear trend for much of eastern Australia isn’t just for the period 1900-2006. In case any one’s concerned that its because we started the comparison in a drought. Take 1910-2006, 1920-2006 or 1930-2006 and you get something similar.

Indeed its not unless you compare with the 1950’s to 1970’s that you get a really marked decrease in rainfall in most of Eastern Australia.


Drying up or typical climatic variation?

10 March, 2007

I noticed this article Big dry: no one knows why in the SMH this week, and in particular the claim that eastern Australia’s rainfall had dried up since the 1950’s. The report seems to be related to this press release announcing a new centre at UNSW studying climate change.

A priority for the new centre is to better understand the mystery of why Australia’s most populated region, the continent’s east coast, has suffered such major declines in rainfall in recent decades.

“We recently had a round-table of Australia’s leading climate-change researchers and this emerged as the biggest unknown issue and, of course, it seriously affects the largest concentration of people stretching right down the coast from Cairns to Melbourne,” Professor England said.

So I had a look again at the rainfall graphs and time series provided by the Bureau of Meteorology for eastern Australia and there is no doubt that we have been receiving less rainfall in recent decades than the 1950’s. However it also seems that we are receiving more rainfall than in the first half of the 20th century, so the question seems to me to be as much why did rainfall rise in the 50’s as why has in fallen in the 80’s and 90’s.

EasternAustraliaAnnualrainfall
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More on the rental crisis hype

5 March, 2007

One of my pet hates is the “research” turned out by real estate industry groups which is always, shall we say, very optimistic whether talking about rental increases or price increases. So I was amused when a friend pointed out this article in the paper on the weekend.

Rather than showing a surge in rents, data from the New South Wales Government shows there was no growth in apartment rental bonds in the three months to December.
In Sydney’s inner suburbs, three-bedroom houses recorded growth of 3.6 per cent but two-bedroom houses also showed zero growth.

Of course this is for the end of last year rather than the start of this year, but it puts the predictions in perspective. As I stated before its not surprising that the real estate industry publishes favourable research to their interests. What is disappointing is that the media outlets, papers, television, radio commercial as well as ABC and SBS almost uniformly regurgitate this uncritically.

Media watch has a more comprehensive hosing down of media gullibility in the face of real estate industry “research”. A fine collection of misquoted tenants, and exagerated stories some being pushed by political parties.