There’s already some finger-pointing about the management of Brisbane’s dams in the weeks leading up to the flood. I don’t want to deal with that while the emergency continues, but I will make a couple of suggestions regarding future policy in Brisbane and elsewhere
* The historical statistics on the frequency of severe rainfall events (both droughts and floods) have proved to be of little value. Everywhere in Australia, we need to work on the assumption that extreme events will be more common in the future than they were in the (pre-2000) past.
* As regards Wivenhoe Dam, we need a much more cautious approach to flood mitigation, going into wet seasons with a substantially larger reserve capacity. This in turn will reduce Wivenhoe’s usefulness as a water supply source, and buffer against drought.
* One response that is immediately available to us is to turn on the water recycling plant, built at great expense during the drought and never used. Current policy is to turn it on when average dam levels are at 40 per cent. This trigger should be raised significantly. As a very rough guide, it appears that when our dams are at 100 per cent of normal we currently have enough storage for four years supply. If instead we cut the maximum to three years supply (75 per cent0, we could (roughly) cancel the impact on supply by turning on the recycling plant at 65 per cent (40+25)
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I’m still on the other side of the planet, but the news from Brisbane is bad and seems to be getting worse. Fortunately, my family and I are all out of harm’s way. Unfortunately, that’s meant we’ve suffered a fair bit of property damage, and won’t be able to do anything about it for some time. I’ll probably be off-air for a while. We’ve had some very successul appeals for help in relation to past disasters here, but I’m not in a position to run one this time. Feel free to use this thread for offers of help to those affected, and any useful insights. Please, no pointscoring or social/political debates – there will be time for that later on.
Hi everyone, The blog has been down for a few days due to a server failure, but that’s fixed now. I’m currently on the road, so posting will be light for a while.
A year or so ago, there was a lot of fuss around the talking point, originating with Richard Lindzen of MIT that “There has been no statistically significant warming since 1995?”At the time, I observed that this meant nothing more than “given the variability in the data, we need at least 15 observations to reject the null hypothesis at 95 per cent confidence”. Thus, it was totally unwarranted to slide, as Lindzen and others did, from “no statistically significant warming” to “no significant warming” or even, in Lindzen’s case “warming has ceased for the past fourteen years”. Sad to say, most of the “sceptics” who profess to “make up their own mind” on the issues, are either too lazy or lack the mental equipment to learn the basic statistics needed to understand this point, and therefore unthinkingly repeated Lindzen’s claim. But, to anyone who understood the issues, it was obvious that a couple more observations in line with the observed warming of recent decades would be enough to bring the trend to statistical significance.
With 2010 over, we now have 16 observations starting in 1995, and (unsurprisingly to anyone who followed the argument thus far) the upward trend is now statistically significant at the 5 per cent level That is, if climate change since 1995 (the time of the first IPCC report, and well after Lindzen announced himself as a sceptic) had been purely random, the odds against such an upward trend would be better than 20 to 1 against.
The obvious question is whether Lindzen will now concede that his claim, and the inference he drew from it, has been falsified, and that warming has not in fact ceased as he suggested. I’m willing to bet that what we see is evasion, obfuscation of or outright silence, not only from Lindzen, but from all of those who parroted his claim.
fn1. My estimates based on the Hadley data used by Lindzen gives an estimated trend of 0.012 degrees a year, with a t-value of 2.45.
Victoria suffered just under 300 deaths in road crashes in 2010. That’s a tragedy nearly every day, but it’s still a small fraction of the toll exacted by motor vehicles 40 years ago, when the road toll peaked at 1061 in 1970 (at at time when there were fewer people and many fewer cars). I couldn’t find a graph for Victoria but here is one for Australia as a whole, showing the same pattern with a slight lag as other states followed Victoria.
Anyone my age or older will remember that, after decades of accepting steadily increasing death rates as the price of mobility, Victorian governments of both political persuasions finally took the politically courageous step of enforcing higher safety standards – first seat belts and automative design rules, then effective techniques to catch and convict speeders and drink drivers, then helmet laws and more stringent license testing, among many others. Victoria’s interventions were eventually followed by other governments in Australia and elsewhere, but the lags are such that Victoria has gone from having some of the most dangerous roads in the world to having some of the safest. Nevertheless, and not surprisingly, these steps aroused plenty of opposition at the time, and the opponents were able to produce supposed experts to back their arguments.
What might seem more surprising is that even after four decades in which their claims have been refuted beyond any reasonable doubt, the same experts are still pushing the same discredited lines, and still finding a ready audience. With a closer look at the experts and their audience, this fact is perhaps less surprising, but still requires some explanation.
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