Dr David Jones, Head of Climate Analysis at the Australian Bureau of Meteorology, has claimed that over the past 11 years Melbourne’s rainfall has been about 20 percent below the long-term average.
It is common to refer to “the long-term average” when discussing climate data, but if the climate along the East Coast of Australia tends to be dominated by either El Nino or La Nina conditions, how meaningful is an average?
According to Associate Professor Stewart Franks, School of Engineering, University of Newcastle, when calculating a long-term average it is important to include an equal number of La Nina and also El Nino dominated periods.
Professor Franks is a hydrologist with an interest in understanding the risk of flooding. He has explained that if you take an annual maxima flood series for a northern New South Wales catchment, which is typical for the East Coast of Australia over the last 100 years, there have been two periods of El Nino conditions and a single La Nina.
So when a long-term average is calculated from this data it probably underestimates the real risk of a big flood event. In other words, if anything government policy and planning has underprepared us for big flood events.
In the opinion piece by Dr Jones entitled ‘Our hot, dry future’ published by Melbourne’s The Age newspaper recently, he claimed the below average rainfall in Melbourne was due to global warming and that there was worse to come.
But if the climate along the East Coast of Australia is a two state process dominated by El Nino or La Nina, then while Melbourne has experienced relatively dry conditions during the past 11 years, the expectation would be that at some point we will move back into a La Nina dominated phase. According to Professor Franks, it is probably a bit messier than that with periods that might not be dominated by either.
Nevertheless, it is reasonable to assume the longer the El Nino dominance continues, the likelier it is to end.
So, rather than preparing for more drought as Dr Jones suggests, perhaps we should prepare for more floods? Indeed climate always changes and floods and droughts are a natural hazard.
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For more information:
D. C Verdon & S. W. Franks, 2006. Long-term behaviour of ENSO: Interactions with the PDO over the past 400 years inferred from paleoclimate records, Geophysical Research Letters, 33.
Part 1 of this series,
https://climatelab.com.au/blog/2008/10/how-melbourne%e2%80%99s-climate-has-changed-a-reply-to-dr-david-jones-part-2/
Part 2 of this series,
https://climatelab.com.au/blog/2008/10/how-melbourne%e2%80%99s-climate-has-changed-a-reply-to-dr-david-jones-part-1/
Part 3 of this series,
https://climatelab.com.au/blog/2008/10/how-melbourne%e2%80%99s-climate-has-changed-a-reply-to-dr-david-jones-part-3/
"got nuttin'"; from you yet, but I live in hope.
"a signal emerging out of the noise look like." The opposite of what Mann, Amman, Sherwood, Santer etc produce I guess.
"McNeil and Cox isn't a climate change study"; Abstract: "This study presents an approach which explores the rate of change in the IPO, in addition to its value, to define an indicator for the climate component of ambient shallow groundwater levels and corresponding stream salinity."
"Stats qualifier"; I presume you mean p4? Refreshingly honest, isn't it?
"got nuttin'"; from you yet, but I live in hope.
"a signal emerging out of the noise look like." The opposite of what Mann, Amman, Sherwood, Santer etc produce I guess.
"McNeil and Cox isn't a climate change study" Abstract: "This study presents an approach which explores the rate of change in the IPO, in addition to its value, to define an indicator for the climate component of ambient shallow groundwater levels and corresponding stream salinity."
"Stats qualifier"; I presume you mean p4? Refreshingly honest, isn't it?
"critiques of the highest order" - oh Cohenite - what a toss. Some unpublished bloke at Emerald with a blog?
Cohenite - McNeil and Cox isn't a climate change study - lordy me. Did you read the stats qualifier BTW on the Queensland study - of course not.
Definitive paper - tell me - what would a signal emerging out of the noise look like?
I enjoyed Rabett's rubbishing of Mislowski's dross too. Ya got nuttin' ....
Having just witnessed Dr Henry's disdain for the collective concerns and need to know of the tax-payers, 'David's' disdain for said tax-payers should come as no surprise; if said government subsidised scientific organisations cannot respond to critiques of the highest order such as those by David Stockwell, then I suppose it is too much to expect that lowly bloggers/rags should be responded to; but if 'David' wants obvious flaws maybe he should get off his highly paid, taxpayer funded backside and inspect some real flaws such as in the Amman and Wahl effort, everything by Mann and the Koutsoyiannis revealed 'flaws' in the whole IPCC GCM apparatus; flaws my pumpernickel; this 'debate' about AGW has been shanghied by a subservient msm, with a few honourable exceptions, and has been conducted by bloggers with no other choice but to blog.
Luke; the Timbal paper says at Figs 6 and 7 that rainfall is no less and temp no higher but runoff to the MDB is less; query the early records? How else to explain, except by the McNeil and Cox effort which notes that IPO variation and landuse change are the determinants, with no space for AGW; are you ever going to give me an unequivocal AGW supportive paper?
Ian - the issue is still before those needing to make a decision which might be to stay or go on the farm. Whether to keep supporting producers with EC or not.
All one can do is patiently and carefully weigh up the information and data available. I find more contemporary research such as http://www3.interscience.wiley.com/journal/116330641/abstract quite sobering.
But decisions do need to be made. Not doing anything is still a decision to maintain the status quo.
Recent work by SEACI - BoM andCSIRO (not the DECR modelling) would give me cause to attribute "some influence" to global warming. That's enough to bias one's risk assessment to think that the last 110 years is not good enough as a representative sample.
However I also have cause to also ponder that the PDO has just flipped too. And that wet years may be wetter. Stewart Franks comments are not ignored.
Luke,
It might be a reasonable question to ask whether the climate probabilities that have been calculated on the experience of the last 110 years ‘will stand us in good stead in the future’ but the whole point of Graham Farquhar’s view is that, as of now, we simply don’t know the answer. It’s one thing to empathise with farmers who are in the unenviable position of having to decide whether and how to ‘invest/withdraw/support/diversify/adapt/move at all levels’, but they’re not helped by Governments that think they know.
The Terms of Reference (ToR) of the DECR, drafted before the exercise began, say that ‘Climate change is expected to increase the frequency, severity and length of drought in the future.’ But if, in Farquhar’s words, ‘some [models are] showing Australia wetting up and some show drying, and the same models with slightly differing starting conditions often giv[ing] different results’, how can such statements be made in advance? (I know why they are, but I don’t think they should be).
In an excellent opinion piece in yesterday’s Canberra Times, Robert Skidelsky recalled John Maynard Keynes’s description of economics as ‘one of those pretty, polite techniques which tries to deal with the present by abstracting from the fact that we know very little about the future.’ Skidelsky went on to say that such aphorisms, ‘which seem so apposite today, were for years dismissed with a pitying smile as the product of a primitive state of economic thinking that had been rendered obsolete by powerful desktop computers and PhD maths unavailable to Keynes’s generation’ (‘Keynes a man for our time’, CT, 27 October 2008, p. 13).
Of course I’m biased in favour of Skidelsky’s views, because he was a member of the all-Party Select Committee of the House of Lords which unanimously concluded that David Henderson and I had ‘helped to generate a valuable literature that calls into question a whole series of issues relating to the IPCC SRES’, and that we had ‘performed a valuable public service.’ I admire the polite but probing questions that his Lordship put to some of the IPCC’s leaders during the Committee’s hearings, and I’m sorry that Australia’s IPCC milieu have not been subjected to similar scrutiny.
I’m not a good person to be asking about a path forward, because it would be the kiss of death for any such path that it had been suggested by me. So far as I know, I’m the only Australian who’s been personally attacked by the IPCC – and earlier this year Dr Clive Hamilton described me, in an article elegantly styled ‘Death rattles of the climate change sceptics’, as one of Australia’s foremost examples of the species. He also claimed that I was ‘associated with the denalists of the Lavoisier Group.’ I don’t know why he thinks so, or why he supposes that this excuses him from engaging in discussion with me even if I did have such an association. Nor do I know why Clive thinks that labelling people ‘denialists’ advances public understanding, but as he was appointed Australia’s first Professor of Public Ethics very soon afterwards it seems that a readiness to heap personal abuse on those who disagree (or 'deny') has become a pre-requisite for advancement in some areas of Australian academia.
All of this make me less optimistic about the prospects of finding a path forward than I was some years ago. So the short answer to your final question is "No".
Ian - governments state and Federal have spent billions of dollars on drought aid, EC, "Save the Murray" and climate related issues since the 1990s. So it seems many people have had their next 200 years worth of EC already.
So it's a reasonable question is it not for individual farmers, agribusiness, water resource managers, policy wallahs and Treasury to know if the climate probabilities we have calculated on the last 110 odd years of measured rainfall will stand us in good stead in the future.
Indeed the decision is to invest/withdraw/support/diversify/adapt/move at all levels.
The drought policy reforms of the early 1990s were to move to a model of "self-reliance". Don't think we've come too far given the outlays.
The other phenomenon is the "hydro-illogical cycle" - as soon as it rains all the climate risk/climate science focus disappears and the issue is revisited again at the next drought - err sorry - period of "dryness".
So the issue of future climate is of some pith and moment for many of us.
Do you have a path forward?