Twenty-third century historians debating who would be so anti-scientific as to associate an episode of extreme weather to climate, and especially to global warming, will have to look no further than two recent blogs on the recent Australian disaster:
- “Is there a link between Adelaide’s heatwave and global warming?” by Barry Brook on BraveNewClimate
- “Bushfires and extreme heat in south-east Australia” by David Karoly on RealClimate
A few things need to be firmly kept in mind:
- as I keep reminding everybody, the debate on Attribution is still open, it is part of a big conference in less than a month, and if anything big would be ready to be presented we would have likely heard about it already
- much of the aforementioned attribution may unfortunately be based just on the GCMs ability to replicate observations, implicitly relying on the modelers’ own mysterious art rather than on actual physics. Doesn’t anybody realize that any pattern can be replicated with any precision given enough degrees of freedom, with or without equations that have anything to do with reality?
- uncertainties working against any present thought of global cooling could honestly be used the other way around
With that in the background, let’s have a look at Brook’s work first. And it is not a pleasant one:
So, in Adelaide we have two freakishly rare extreme events happening with a 10 month period. How likely is that? Well, if the events are totally independent, we’d expect the joint likelihood of two such heatwaves (of 0.25% probability per year [the 2009 event] and 0.033% per year [2008 event], respectively), occurring within the same 12 month period, to happen about once every 1,200,000 years. Is that unlikely enough for you? But if there is ‘autocorrelation’ (dependencies between the two events due to a linked cause — such as climate change), this calculated probability is not valid.
If that isn’t a true example of why statistics have such a bad reputation (“lies, damned lies, and…”), then I do not know what is. And if that doesn’t show that Brook cannot properly talk about climate, as he doesn’t look like having even the faintest clue of what makes some days warmer than others, then I do not know what does.
And what does make some days warmer than others? Weather. By definition.
The 2009 Australian summer around Adelaide and Melbourne has seen some particularly hot days because of a peculiar weather pattern, with winds bringing hot, dry desert air towards the inhabited coast (there might have been also an intervening Foehn (warming) effect, but let’s keep that aside for the moment).
The underlying weather pattern has been described by the National Climate Centre at the Australian Government’s Bureau of Metereology:
The presence of a slow-moving high pressure system in the Tasman Sea, combined with an intense tropical low off the northwest coast of Western Australia and an active monsoon trough, provided the ideal conditions for hot tropical air to be directed over the southern parts of the continent
NASA’s Land Surface Temperature Anomaly picture reinforces this point: one can clearly see how warm air has been pushed towards Victoria, just as cool air towards Queensland. And an intervening band in the middle has then experienced whatever temperatures it usually experiences.
It’s just the same air movement. If you push “oceanic air” over Queensland, the existing “Queensland air” will move towards Victoria, and so on and so forth closing the high-pressure system circle somewhere to the East of Australia. You can get a similar result with a low-pressure system somewhere to the West too. If the two combine, so much more evident the Queensland cooling and Victoria warming. Does one need to be a veteran metereologist to understand such an easy point?
Even the briefest introduction to metereology and climatology should make very clear to everybody how incredibly naïve and totally anti-scientific is the belief that “global warming” means hotter days in this or that part of the planet. In fact, the question Brook should have asked is: do that “slow-moving high-pressure system” and “intense tropical low” in those particular places, and that “monsoon trough”, have anything to do with (anthropogenic) climate change?
But of course Brook just about cannot get anywhere in that direction
Who knows, one day he may wake up to a 2007 paper, three years later that is, by Chase et al. published in the Geophysical Research Letters, asking “Was the 2003 European summer heat wave unusual in a global context?” and responding
Regression analyses do not provide strong support for the idea that regional heat or cold waves are significantly increasing or decreasing with time during the period considered here (1979–2003)
I am all for free speech, and Brook and the likes can keep on blaming perversity for the worst kind of climate change denial but there must be a point where they have to recognize how silly it is to appeal to science without understanding a iota of it.
Karoly’s contribution is of a different quality, with no absolute-weather-beginner mistaken mention of reality-divorced probabilities (Karoly even talks, briefly, about weather patterns…).
His point appears to be a rather old one though. Why would heatwaves be attributable to anthropogenic global warming? Because Karoly himself, with Braganza, managed some time ago to simulate observations using climate models that include “increasing atmospheric greenhouse gases and aerosols” (see his 2004 paper referred to in the blog).
Actually, to be more precise, what happened is that Karoly and Braganza were unable to simulate observations using “natural climate variations alone“. Perish the thought that the problem might have been an inappropriate definition of those “natural climate variations”…
In any case, given the apparent strength of Karoly’s convictions dating from 2004, one might start wondering why the Chair for the “Detection and Attribution: State of Play in 2009” (Parallel Session 9) in Copenhagen would be Ann Henderson-Sellers of all people. Who she? The one claiming in the session’s very description that
the detection and attribution story was incomplete [at the time of the IPCC AR4 in 2007] due to ‘Key Uncertainties’ listed by IPCC
and listing in a September 2008 article, among the seven “Serious inadequacies in climate change prediction that are of real concern”
- The rush to emphasize regional climate does not have a scientifically sound basis […]
- Until and unless major oscillations in the Earth System (El Nino-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO) etc.) can be predicted to the extent that they are predictable, regional climate is not a well defined problem. […]
Notice how Henderson-Sellers goes on to say that “WGII is easily the weakest of the three reports. The reasons seem to be two-fold: (i) poor downscaling and (ii) the lack of a coherent methodology for impact study“.
I am sorry for Prof. Karoly but either Prof. Henderson-Sellers is very wrong on more than one point (and then what would she be doing as Chair of one session in Copenhagen?); or Karoly’s own 2004 work, and his present stance are just an example of what Henderson-Sellers describes as the rushed, scientifically unsound regional climate emphasis around a non-well-defined problem, plagued by poor downscaling and dealing with a climatic impact without a well-recognized methodology.
Does Karoly understand this problem? I think he does. Cue his large caveat about his large claim
Although formal attribution studies quantifying the influence of climate change on the increased likelihood of extreme fire danger in south-east Australia have not yet been undertaken, it is very likely that there has been such an influence
Karoly’s own language gymnastics is remarkable, with just about the right mix of “clear” and “likely” to pass most logic tests, in case things don’t turn up as expected. He’s not the first athlete to enter such a competition though.
Finally, it certainly doesn’t look too good when Karoly provides three papers linking “observed and expected increases in forest fire activity […] to climate change” but no mention of the lack of any comprehensive analysis (think of the absence of trends in fires around the Mediterranean region for example).
It is rather sad to see what started as the science of climate turning pretty much into a parody, with reports and explanations forever running after the latest disaster. Very simply, this cannot be right.