Hi Jennifer,
There has been substantial discussion on the blog over the last few months as to the severity of the current drought afflicting much of Australia and its cause. A fair emphasis has been as to whether the current drought is the “absolute worst” on record or whether they have been “historical anecdotes and personal rainfall data sets before sufficient formal Bureau records, or paleological droughts recorded in coral cores” that were worse. Via the Australian newspaper, Barrie Hunt has contributed the results of a 10,000 year Global Climate Model run to further complicate this argument suggesting we only have a narrow view of what our real climate variability involves.
To some extent does it really matter? Is it just a public bar sports debating point. We know that the drought is widespread, severe, entrenched and multi-year in nature. It’s not much fun if you’re in the middle of it. Surely it is “among” the worst droughts on record in many important areas. All droughts have their own unique signatures and different areas show different impacts. It is simply not possible to say whether this drought is other than natural variability – although one can argue there may be climate change aspects or influences exacerbating the situation. We’ll know for sure in 30-40 years time.
What does matter is to whether we are adapting and responding to drought risk, water security, land use and population changes in a more mature manner. This involves seeing drought as part of normal and planning for it appropriately at farm, regional, industry, state and national levels.
Nevertheless I believe we do need a better spatial understanding of this multi-year drought which some have said has been building for 5, 6 or 7 years. A reasonable way to do this is to undertake a decile analysis of rainfall for the Australian rainfall network. We need to examine how bad the sequence of years are for rainfall deficit. The Bureau of Meteorology has come under quite a bit of criticism by blog commentators, but notwithstanding, I asked Dr David Jones, Head of Climate Analysis, from the National Climate Centre to supply a 5 year and a 7 year decile sequence analysis for their reference network which he has kindly provided. Why debate the issue in a data free vacuum when we can make a phone call or email !
The analyses are included as maps below.
The maps represent a 5 and 7 year decile analyses based on the sequence of 1900 till now. For example – where does the recent 5 or 7 annual rainfall sequences fit into any of the sequences since 1900.
Anyone can easily do these analyses for a single station or stations – you just need to do the mathematics of adding up the year-totals in a running mean fashion and grouping your data into decile bins. So for the five year decile – arrange your data from earliest to latest records, add up the first 5 years in the record and record the total, move the band along one on the rainfall record sequence and do it again, and so on and so on. When all done, rank the new totals highest to lowest in decile bins (0-10%, 20-30%, 30-40% and so on). You can then see where any individual sequence, or the last 5 years in this case, fits in the distribution of all 5 year sequences. Or in fine detail the lowest and highest on record.
Similar logic for the 7 year analysis.
But as you may appreciate a lot of work to do spatially and interpolate the results.
And it is important that it is done as a sequence of years – one cannot add the individual year deciles/percentiles together.
The maps unlike the time series show we live in two Australias – one wetter and one drier. In the majority of areas where we have major agriculture or urban populations we have drought issues – some moderate – some severe in parts. Meanwhile life in the Gibson desert is pretty good (relatively speaking). This why the times series data are not helpful – the addition of real good and real bad = average which doesn’t represent reality
Of course this is only rainfall – there are obvious issues of pattern and intensity of rainfall, how plants and soil respond, and antecedent conditions (i.e catchments currently dry as a chip) – if we’re debating streams and rivers I really think one needs the same analysis but on streamflow.
Similarly one can use a pasture or crop model to get decile crop yields or pasture biomass (decile of wheat and grass!) However experience suggests that often these further analyses amplify effects and it will look worse for drought. Usually same with streamflow.
I understand the Bureau will be undertaking some more work on this issue in coming months.
I encourage any readers to do their own numbers with their own data – but please explain what you have done so we’re all clear.
Cheers,
Luke.
PS obviously where station density is low – i.e. central Australia and central WA the spatial interpolation is only as good as the data point grid. But I believe we have a sufficient grid for some intelligent analysis in areas that people live or major agriculture occurs. One could obviously argue the spatial interpolation mathematics and accuracy in fine small areas (i.e. SE Qld). The data do not start in the 1890s and the Bureau do have issues with station quality before 1900. The data are of mixed quality.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
“And I find it utterly fascinating that you’d jump on some blog article unrefereed and unclear – but reject the peer reviewed literature. Amazing logic – but that’s what’s loopy fanatics do eh?”
This was your response to Ian Mott when he engaged in some discussion regarding data of interest…..only a few hours ago.
I take that according to your own advice one should therefore treat this effort by your self in the same manner. It fits all your own criteria,including the last one.
As a comment on the variability of rainfall, on News Year eve we had a stormcell move from Bredbo north to Canberra.
A farmer at Colinton registered 104 mm and just up the road at Michelago Shop recorded 10mm.
At our house 10 km east of the Monaro Hwy adjcent to these locations we had 3mm.
Driving through to Canberra the following day, the flood damage done to fences was extensive.
At Willamsdale there were sheep that had drowned against a fence which wasn’t at any noticable water course.
Many hundreds of tonnes of soil filled drains and dams along the Monaro Hwy in the ACT.
The Canberra Times had coverage of the damage done in Canberra’s south western suburbs by hail and flash flooding.
Yet Canberra AP raingauge registered nil.
The question I have to the scientist’s amongst you is how does all this climate-modelling take into account events that have happened away from the offical met sites.
At least a lot of farm dams are now full for those under the track of this particular gully-gusher!!!
Thanks for some interesting maps, Luke. For the SW corner (where I live) the last five years look a bit more cheerful than the past seven. We have had a couple of wetter than average winters, although dry autumns seem to go on for ever. I think a lot of the fiery debate comes from careless language. Terms such as ‘the driest’ or ‘the hottest’ can mean many things, and few people are statistically mature. I doubt if folk near Esperance are worried about drought at the moment – if BoM is right, they are about to get a drenching. Is there a danger that we are getting a bit like the Michael Palin character who was obsessed with Yorkshire rainfall records, and coal shovels?
P.S. I still reckon it’s connected with submarine fumarole activity in the Southern Ocean and Pacific. God told me.
Suits me Malcolm – you’re a waste of space anyway and if you empathise with the very meekly kindly spoken Mr Mott’s manners well toodley loo – hello is usually spiv and scum – so he gets what he gives but he also gets due consideration and lots of work between the insults – I do attempt to address his issues as well as getting in few insults – we have respect for each other – (as mutually opposing scumoids)
but anyway moving right along can you explain what Jonathon blog person has really done – which data – what time periods.
Allan –
(a) it’s not modelling – simply an elementary analysis of observed data
(b) yes everyone has rain gauge stories – but if it doesn’t get into the network they don’t know about it. Sampling error is an important issue yes. But are the stations a representative network on this issue of drought is the question. But if you think the error is insurmountable then we don’t know anything!
Davey – yes pattern of rainfall, seasonality is an issue – that’s why you would be better using a wheat model to integrate these issues for WA.
Are we obsessed – yep – doing an evidence job with Sid. We’ll be checking his own analysis soon when he posts.
That damn Southern Oscillation and related El Nino will do this to rainfall. Did it during WW I and WW II to a similar duration as today but there’s been several spells of shorter but more intense El Nino. What a bugger these are natural events, eh ?
Luke, can you get the details of cyclones over the same period?
I spent quite a few years, playing with tourist boats in Queensland, & I know that we are getting a lot less cyclones on the Queensland coast, than we did, in the 70s & 80s.
You do remember cyclones, when you spend days, eaten by sand flies, hiding your boats, up mangrove creeks.
Those cyclones often turned into extra tropical storms, with very large rainfall stretching to Victoria.
At the same time, there is a large increase in cyclones, reported on the WA coast.
The areas of rainfall change do tend to correlate, to a large extent, with the areas which would benefit from cyclone rains.
It would be interresting to confirm the reality of my memories, & see if that is part of the answer.
You could have lots of fun, telling us why GW results in less cyclones, in Qld, more in WA, & if there is any other reason, other than random variation, for the whole thing.
John – we’re in an El Nino this year and 2002 was too – but that’s not the whole explanation. The other years in between haven’t yielded much rain? Only about half the rainfall variation is due to ENSO.
Hasbeen – for tropocal cyclone stats have a look at http://australiasevereweather.com/cyclones/history.htm
Yes there have been very few coast crossing tropical cyclones in Queensland. And that’s how dams and aquifers get filled quickly ! Cyclones track across Cape York, the Top End and around NW WA. Warming in Indian Ocean ? (Save cyclone Larry)
So why the drop-off in coast crossing cyclones in Qld. El Nino tends to make them stay out to sea but not all years have been El Nino.
One speculation is that changes in the southern hemisphere circulation from the southern annular mode/ozone issue which is moving the rainfall belts south of the continent (implicated in causing southern droughts) also coincidentally causes shear forces across the Coral Sea which prevents cyclone formation. It’s a theory. The shear forces don’t extend to the far north and Cape York where storms like Ingrid traversed.
Also worth reading
http://wind.mit.edu/~emanuel/anthro2.htm
Luke,
It appears that CSIRO and BoM are syncing –
http://www.theaustralian.news.com.au/story/0,20867,21008378-601,00.html
acknowledging the reality of climate change but clearly not drawing any links between AGW and the current drought – this drought is within natural variability parameters.
The fact is that the majority of experts believe human activity is the reason for recent warming.
That contention isn’t changed by acknowledging that the current drought probably isn’t a result of AGW.
This is what I suspect this bloke;
http://scienceblogs.com/nosenada/2006/12/so_what_happened_at_agu_last_w.php
was referring to when he talks about “overselling”.
Far safer and decidely more honest to stick with the view of experts complete with caveat’s and uncertainties rather than risk a backlash from the public if they find out that much of what they’ve been told is untrue.
Otherwise agree with your comments. Especially;
“What does matter is to whether we are adapting and responding to drought risk, water security, land use and population changes in a more mature manner. This involves seeing drought as part of normal and planning for it appropriately at farm, regional, industry, state and national levels.”
Jim – thanks great post. Nosenda blog comments very pertinent.
RC are also playing same vibe:
http://www.realclimate.org/index.php/archives/2007/01/consensus-as-the-new-heresy/
Australian newspaper reporting Murray River at lowest inflows on record.
http://www.theaustralian.news.com.au/story/0,20867,21008372-601,00.html
Jim, too much for me in your conclusion /comment:’acknowledging that the current drought probably isn’t a result of AGW’. So , easy and gently qualitatively for starters; current climate is a child of global warming -current drought is a child of current climate.You have cut a chord. The issue quantitatively is one of a very uncertain degree ( or two) so any rational or even intuitive risk manager would accept it is either a lot or a little and plan accordingly. Accept that logic and the rest is rational.
This is just another set of cute pickies from BOM. The only reason southern Qld is in the 1st decile range is the lack of excessively wet Februarys and Marchs. The 100 year set for Eudlo on SSCoast shows we are not in a 1st decile phase. Ditto the 100 year set for Mullumbimby Nthn NSW.
This is a repeat of this institutionalised lunacy of measuring totals laced with value judgements rather than effective falls. The BOM is tallying up past flood excesses in February as some sort of implied “good” and allowing the gonzorati to conclude that a mere 100mm in October is some sort of decline.
Raw rainfall data is nothing more than a very quick and definitive way to identify the ignorant, the plain stupid, and public sector water mafiosi.
Rainfall data is irrelevant if it is not expressed in terms of its timeliness and impact on soil moisture. It must be expressed in a context of evapotranspiration balance so we can understand its ecological contribution.
900mm in March is a pain in the “ask your mother for sixpence”. It quite often obscures some very dry Spring/Summer seasons while March totals that barely match ET can be associated with Spring/Summer seasons of minimal soil moisture deficit.
If this is the most informative stuff that Luke and his mates in the Ministry of Truth can coax out of BOM then we really do have a problem.
No Ian – it was simply an analysis asked for. And a simple analysis. I asked and they had the information available. Perhaps you might trying asking too instead of being a whinging disingenuous creep. And it was in response to Sid suggesting the rainfall numbers were exceptional or not. So some numbers have been put up.
But gee Ian if ya wanna get more sophisticated you’d have to model stuff and we know how much you love that (not!). If you note I had suggested such in my post and also the issue with fine detail in SEQ. Of course I could waste BoM’s time and ask for a high res map but why bother for the likes of you.
The modelled inflows (which Ian doesn’t believe anyway) show Wivenhoe catchment worst on record and Murray is joining them. That’s that – game set and match. It’s hasn’t frigging rained Ian – over the catchment – Ian. That’s what we’re on about Ian. If every dude in Brisvegas wants a rainwater tank or to drink their own wee – well fine Ian ! Another issue.
Eudlo and yokel-ville Mullimby seems to not be in the catchment. Have another drag on your Nimbin herbal remedies Ian and contemplate the miracle that water tends to run down hill.
Really you’re just a whining public scientist abuse merchant aren’t you? Frankly I don’t give a stuff whether you believe the numbers or not. They’re produced in good faith and their content and limits described.
Anyway Ian get off your arse and produce some information yourself instead of vitriole. When you assume power with the rest of property rights nut cases and assorted pompous blowhards we may look up.
I’ll accept BoM and CSIRO’s refusal to draw such a link as the expert view bazza.
I repeat , there’s no need to “prove” the current drought is a consequence of AGW – the science is widely accepted.
Some variations in weather and rainfall will be AGW linked , some won’t.
Please Jim can you show the quote where CSIRO and BOM ‘refused to draw a link’between current drought and AGW. If you want to conclude that you would have to dismiss the following quote from the BOM report ‘The dominant cause of the drought experienced throughout southeast Australia in 2006 was the development of an El Niño in the tropical Pacific Ocean. However, Australia has experienced marked rainfall trends over the last 50 years with declines over southern and eastern Australia and increases across the northwest. The pattern of rainfall during 2006 continued this trend. ‘ The risk managers that survive are comfortable with ambiguity and recognise that because the current drought is within the realms of natural variability, the realms may well be achanging.
Bazza ,
From the first link;
Bureau meteorologist Blair Trewin said rainfall in most drought-afflicted regions had not “gone beyond the bounds of what you could plausibly see with natural variability”.
From
http://news.ninemsn.com.au/article.aspx?id=64618
It is very, very highly likely that what we are seeing at the moment is natural climatic variability,” The Australian quoted Mr Hunt as saying.
“When people talk about it as a 1,000-year drought, they haven’t got the information. They don’t understand that according to natural variability we could get another one in 50 years or it might be another 800 years, and there’s no way of predicting it”
Now as I note ( for the third time ) ; both articles readily acknowledge the existence of climate change ( implied AGW ) but do not link it to the current drought.
The realms may be achanging – or may not.
It’s not necessary to insist every variation in climate or weather is caused by AGW for the theory to survive and in fact doing so could backfire.
When the current drought breaks next week, month or year , Joe Public may reasonably conclude that those who blamed it on AGW were full of merde.
Touchy, touchy, Luke. The so-called serious drought in the catchment is only a problem for those who have been silly enough to depend on the Dams. The trees in the catchment, especially the expanding area of regrowth, and all the species that live in and around those trees, are all having a reasonably good year.
Nature has always intended that the trees will get their fill before the creeks and dams. So the dams, and those that depend on them, are doing it much tougher than the ecosystems that they are linked to.
And once again, the official stats tend to measure things that are of most relevance to officialdom. The Possums, meanwhile, couldn’t give a tinkers Cuss Cuss.
Jim – the drought could break tommorrow – check that big cloud mass on the way from WA ! but AGW could still be there. Or both.
I do agree that Joe and Jill public are probably fairly fickle about all this and may jump around between camps – but we know that the hydrological errr hydro-illogical cycle will turn full wheel and people forget about droughts after it rains. Farmers are eternal optimists – you’d have to be.
I suggest different “experts” will say differnet things as to their research interests and knowledge of the evidence.
(1) it is unclear and one cannot be definitive
(2) yes there are multi-year droughts in the Australian climate record
(3) coral cores probably show some longer ones for northern Qld
(4) Barrie Hunt has an interesting model run – I give it some sympathy
(5) we have had more Los Ninos than Las Ninas since 1976 including back to back events in teh 1990s
(6) the IPCC say the effect of AGW on El Nino is unclear. SOme simulations have no impact – others increase impacts
(7) Hansen has now suggested in recent PNAS paper that perhaps we will see a trend to more severe Los Ninos but not more frequent
(8) Fair bit of evidence that the ozone hole/southern annular mode/poalr vortex issues has changed southern hemisphere circulation moving rainfall south into the ocean
(9) Qld has few coast crossing cyclones since the 1970s – there’s some evidence that the Antarctica changes may be involved in this
(10) Nicholls has said the higher temperatures added a greenhouse component to the 2002 drought
(11) Murray inflows are now near worst on record
(12) Brisbane major dam catchment is worst on record for inflows.
(13) Melbourne and Perth catchments have had very low inflows too
(14) AGW is only just getting going. Not at 2x CO2 yet.
(15) we may have different climates during the transitional phase where CO2 climbs to the stabilisation phase.
(16) At some point the ozone hole will improve/correct (40-50 years time maybe) but then CO2 will be much higher
(17) There are other influences like the Interdecadal Pacific Oscillation out there
(18) and don’t forget SW Qld has been a very bad drouight area (not as well reported)
So with all this going there are bound to be different opinions among scientists.
You won’t be total satisfaction.
But as Bazza points out – what does the water resource manager or smart farmer do with all this information – how do they manage their risk better in the midst of all this ?
For those without water the situation is bad. Those who have sufficient may be concerned about those without. Politics has a role to play.
However, out of chaos comes order. The orders are (as issued by government and their supporters).
The Downside.
1. Wash only once a week (Like the Pomes do.)
2. Don’t grow veggies in the garden to supplement pensions. (It reduces sales at the supermarket)
3. Flowers can be imported.(but only from Iceland)
4. Health regulations on “grey” water are eased. (but we’ll do you for severe violations)
5. Severe penalties, including imprisonment, apply to all those little rules we can dream up).
The Upside.
1. Government is working – we are passing more “laws.”
2. Employment is increasing. We now have “Water Use Police (WUP) in all areas.
3. User pays (again) chargeing will replace value charges.
All suggestions that we can bring water from the North to the Dry South will receive the usual dose of government ridicule, vilification, and abuse to prove that it not a viable proposition. (Of course its not. Do you really expect 5 states and 2 teritories to come to an agreement within the lifetime of the current drought?)
Luke is still flogging the low murray inflows as climate related when even the dumber than duck $hit have worked out that this low inflow has resulted from the increased regrowth from the 2003 fires which used more of the rainfall before it got into the river system.
There once was a time when all the consequences of government incompetence were blamed on the devil. People started to see through that one so they trotted out the old global warming chestnut.
New terminology, same old cop outs.
Crap – you have no serious in situ data to support that. Lowest on record rainfall in headwaters = lowest inflows. A duh ! Occams razor perhaps?
Ian – I need to see your quantitative confirmation of thickening of the catchment – areal extent and net simulated effect over the last 100 years please. Time for you do some work for a change.
P.S. Ian is an apologist for the forestry industry and land clearing fraternity (unfortunately lacks the pre-reqs of being “softly spoken” and even through pretending to speak for western rural folks lives in comfy mild temperatures and slight balmy humidity of Byron Bay environs. Any way of spinning the story back to lack of cutting trees down is a regular obsession trotted out without quantification.
And no rainfall analysis from Sid. Sigh. Broken hearted.
And Ian – BTW I did enjoy the Lou Reed quip – I quite like that song actually. Reminds me of management.
Ian; “Luke is still flogging the low Murray inflows as climate related when even the dumber than duck $hit have worked out that this low inflow has resulted from the increased regrowth from the 2003 fires which used more of the rainfall before it got into the river system”
Allan says “Driving through to Canberra the following day, the flood damage done to fences was extensive.
At Willamsdale there were sheep that had drowned against a fence which wasn’t at any noticable water course.
Many hundreds of tonnes of soil filled drains and dams along the Monaro Hwy in the ACT”
I say any rain including the hail last week etc that fell in our part of the Murray Darling catchment shot straight down the river because of drought, There is no grass or regrowth in most of the Monaro district, neither was there much snow in the highlands to feed the other rivers on the far side.
Ian: Flash floods are a feature of living in this drought but our official records (ACTEW) show no improvement in our water storages as a result of recent heavy downpours. Simply, not enough fell over the Cotter.
Although our creek too went up and down like a yo yo the floods over Ginninderra Falls probably all evaporated by the time they hit Burrinjuck Dam on the Murrumbidgee
Luke: I sometimes get on to the issue of freak storms, those intense and destructive events that have a remarkably narrow path.
The most unusual sucked their energy from the warm summer waters of Bass Strait. My simple explanation used to be based on my understanding of vortex phenomena but in retrospect few of these thunderstorms were established as classic tornadoes.
A few days ago I saw another giant electrified upper atmosphere cloud formation over Jervis Bay and there was no rain or external lightening bolts. It was also too distant or too high to hear but it was completely illuminating with internal flashes like an old fashioned neon sign.
I was reminded of one Christmas holiday way back when the airline put their old DC4 cargo plane back on the passenger run for the peak period. That storm descended mid strait and joined the sea. Our pilot gave us several extra hours of fancy flying under the damn thing. I had plenty of time to observe and notice how we became part of the charge path just a few meters above the waves.
Out last big hail storm here ended suddenly with a very loud overhead bang. It seemed for quite a while the whole world had stopped. The wind and hail were reduced to only a light but soaking drizzle. Our violent storm cell had collapsed in an instant.
Some photos from other places of this storm (by reporters who were driving round) were published. They don’t know what they missed.
Hmmmn, Lou Reed and management, eh. You mean like;
“hitch-hiked all the way from South of A,
plucked his eyebrows on the way,
shaved his legs and he was a DG”?
Still one of the best Sax riffs of all time.
But Luke, you know perfectly well that most of the forest burned in 2003 was in the “Sparks and Wildfires” national estate and the one thing those people are particularly good at is avoiding any sort of research that would expose the extent of their negligence or the character and scale of the damage they have done to their own forest ecosystems.
And, of course, much of it has been burned again this summer, taking out any nest hollows that might have survived the last conflagration.
But I do recall a recent ABC news item (Oct/Nov)that was suddenly talking up the marvellous regeneration of the areas burned in 2003. And as for the response of catchment water yield to regrowth events, you know perfectly well how to google the work of current head of CSIRO Soil & Water, Robert Vertessy who nailed all this stuff down more than a decade ago.
And frankly, it is all a bit rich for some dude on the public purse to be demanding that a private citizen with zero access to public research funding should be conducting broadscale research on his own time for the public good.
So can we now add boorish hypocrite to your extensive list of honorifics? Shall we call it a BhD. (for boorish hypocrite, departmental)?
I just spat my coffee all over my computer – now Ian that was funny. (cripes – I mean herbal tea and soy milk – need to keep up appearances) Pity we’re so alike.
I found this video for you.
Thought you would enjoy Canberra forecast.
Looking forward to your departmental version
And lastly Ian’s reponse to greenies and soy milk drinkers
http://www.youtube.com/watch?v=1EY7lYRneHc
But seriously Ian – you have still failed to demonstrate anything wrong lowest on record rainfall producing lowest on record inflows. OK so we have some on-off boutique work by Vertessy in a boutique catchment somewhere. But how much of an effect is it – does it apply the Murray catchments. This is an evidence based blog. And there were firse in the 1902 drought sequence too so it’s about even.
Ian – it hasn’t rained. Harden the f up ! (see video above for context).
Ian: When I finally got outside after the birds woke me up it seemed we had a decent fall of light rain overnight. I had to shake the water off the plastic wrapped newspaper on the drive even the cats came straight back in after a quick sortie.
The water was all gone after I read the headlines and a couple of threads on the blog
Howzat?
Other readers may note that any runoff from my place should it ever eventuate flows virtually straight into the Murrumbidgee, one of three great rivers in the middle of the system that finally feeds Adelaide half way round the southern coastline.
Also note I don’t take kindly to people living beyond my reach who wish to mess the official records to suit their own selfish purpose what ever it be. I go on and on to Jennifer that by looking out the window we can see all the dust and misery.
In a normal week I can chat to dozens of folk who live outside their PC and I say its their views we must value in the end.
In news today “Farmers wait for dust to settle – ACT deluge misses its mark”
The BIG DRY!
The Sweeneys of Tarago with 28,000 sheep got 13mm and 10 mm.
I bet most of it evaporated like my lot. Vineyards too are parched. Agriculture and industry are at risk everywhere in SE Australia. It’s a very serious situation indeed.
A study on the ‘Googong Catchment, The State of Drainage Networks and Trend in Catchment Conditions since 1944’ by Barry Starr for ACTEW published January 2000 gives confirmation of ‘thickening’ in this particular catchment.
From the executive summary
“Changes in tree cover have been dominated by natural regeneration, mainly of areas clear in 1944. In all, the total area of regeneration in the catchment is three times that of the area cleared during the same period.These figures support a general analysis that grazing land use in the catchment has become less intense over the past 55 years”
Starr used aerial photographs from 1944, 1976 and 1992 for his comparative analysis.
He has concern though “regarding pathogen export to Googong Dam from the catchment.”
All those failed or failing wastewater disposal systems in the rural residental developements.
Look’s like Canberra is already drinking recycled wastewater!
Melbourne Board of Works (BoW)has robust and long term data for the Melbourne catchment that demonstrates the reduction in inflows due to regenerating forest after fire.
After the 1939 fires it took over 50 years for the inflows to return to pre fire levels. In that particulr case it was E.regnans (Mountain Ash, Swamp Gum) possibly the Eucalypt that is least able to moderate its water use that was the dominant tree species in the catchment.
However it does serve to demonstrate that post fire regrowth in Eucalypt forests will result in dramatically reduced inflows and yes there will be variation with different species.
Up it Brindabella’s, west of Canberra, the post fire regrowth has now become well established. It would be an interesting exercise to find out the changes in the inflows, adjusted for rainfall, to Corin Dam in the upper catchment over the past 4 years to pre-bushfire records.
I suspect that 2003-2005 years will most likely have been higher and that 2006 would likely demostrate that the post fire regeneration was exercising its priority to what ever rainfall fell in the catchment.
Gentlemen, your thoughts on this?
Yes Peter saw that news on BoW research.
The way it was done by the CRC Catchment Hydrology was to model the issue.
But it’s not simple without all the modelling kit and data – what forest areas for the catchment at what growth stage, soil depths, soil types, what areas are untouched by fire.
Given MDBC probably have skill in their catchment models, how much of this is parameterised in if it’s a lumped parameter model versus something more spatially explicit with varying land use/vegetation. Assuming it’s parameterised in for the current assessment the situation might be even worse if you have extra evapotranspiration from regrowth trees. Ian may get a worse answer than he thinks ! So be careful for what you wish for.
You would also need to know forest fire patterns if any, in the headwaters during the 1895-1902 drought sequence if you want to stay fair an be comapring apples with apples.
However BoM are saying the Murray and Snowy headwaters have had record low rainfall over a 5 and 7 year decile analysis, and this year, as well as record dry patches at 24 months and 36 months deciles. Despite all the caveats discussed above – very low rain = very low runoff is an Occam’s razor starting point.
Also not well done if you want to get right into the nitty gritty would be the evaporation from wet leaves in moderate showers. Can be significant.
Motty’s task is to get hold of the spatial fire history and land use change map of the catchment back to 1895.
In any case if it does not rain significantly by mid 2007 it will an undisputed record.
Sorry Luke cannot agree with youe modelling assessment.
The BoM data is real its a record of what has occurred and does not rely on model, with all the associated assumptions and data issues, to arrive at its conclusions.
The CRC relies on Zhang’s curves, and Vertesey’s experimental catchment studies. Both of which are unreliable at the spatial extent that we are discussing.
As for the MDBC, their ability to model the basin is poor in the extreme. Partially due to the unbelievably poor quality of their data (which is neglectful in the extreme given their funding over the past 15 years) and the inability of their models to explain just what does happen to evaporated and transpired water. Indeed the Bureau of Meteorology is equally derelict in its modelling in this regard.
Eucalypt physiology is well understood and regrowth trees will certainly have greater levels of transpiration than overmature trees. Unfortunately any half decent runoff model requires a quality vegetation model for a number of parameters including species distribution, stand structure and age classes. Robust and reliable vegetation data is not available for the entire murray darling basin. Rendering mostly unreliable the outputs of any models relying on such data. Motty’s task is therefore impossible, if we cannot map the vegetation within the Murray-Darling basin today with any reliability, we certainly are unable to to do so for the period 1895-1902. As for spatial fire history, try getting hold of any fire history dating back geater than five years, it becomes the inquisition as soon as one asks for data. My guess is that it is too politically sensitive.
One thing that does intrigue me is the almost religeous belief in model outputs. These things are at best a simple representation of what is real and are only capable of providing insights into what may be, and don’t get me started on the misuse of stated assumptions, probabilities and error bounds.
I’ll not disput low rainfall = low runoff, self evident really. Very low rainfall + post fire regrowth = extremely low runoff. Canberran’s are just beginning to understand this, though our water supplier (ACTEW) is still in denial.
Peter – indeed but are we talking about modelling the Basin or just the upper Murray catchment itself. To some extent this whole discussion is to answer the pub bar question of “is the drought in that part of the world worst on record”. Of course the question also gets into the politics of climate change, tree clearing and forest management.
So I was trying to indulge Motty in a semi-modelling, GIS mapping and remote sensing exercise to answer his quibbles but as you have described yes his task is nigh impossible. However an appropriately resourced landscape and hydrology modelling outfit (big big bucks and some considerable talent) could perhaps have a go at it.
And agree with your last comment – very low /record low rainfall + post fire regrowth is a double whammy ! So leaving it as it with no assessment of fire evenstg 1985-1902 it would make the assessment definitely worst on record.
There is no religious belief in models – just simply how else do your even get an edge on interactions. Proof is always in the validation. If you don’t like model – try big accounting spreadsheet with docuemntation of steps.
Of course the problem with this sort of modelling is you can get the right answers for the wrong reasons, and processes that don’t validate at small scales can validate at large scales. I think it’s called “emergent properties”. Simulation is always the art of the plausible – do we discount our outliers?
Holmes & Sinclair developed their model from 21 Victorian catchments in 1986. Zhang merely confirmed it all and confirmed the direct causal relationship between increased evapotranspiration and increased leaf area index.
And thats all right Luke, I’ll just do the MDBC’s job for them on my own time and budget while they do the workshops and drink the tea. Plus ca change.
And as for Lou Reed, your task is to come up with the next verse that includes, “in the back room he was every body’s darling”. Don’t lose your head now.
Luke, Is the current drought the worst on record? Does it really matter when temporally our record is so short? What really needs to be answered is: is the duration and severity of the current drought an anomoly in the long term record (using proxies)or is it a recurring event? CSIRO have recently indicated that the probability is high that it is indeed consistent with the long term record.
Is the current drought evidence of AGW? Given our current level of understanding of climate the balance of probability would suggest not. Give it another 5 years or so and that balance may change.
Agreed that proof is in the validation, however data quality is still crucial and an understanding of the assumptions and model type are paramount when interpreting the model.
IPCC climate models are a good example; deterministic models that model a suite of scenario’s and do not produce a predictive outcome. Yet time and again the results of the IPCC models are referred to as predictions of what will happen as opposed to scenario’s that may occur given a set of extremely tight circumstances.
As for validation of such models, it is nigh impossisible to do more than cross validate against the data set as stochastic methods are unsuitable. Generally they remain untested and untestable. But they do provide insights into the physical processes associated with climate systems.
As deterministic models are not stochastic in nature they are not so much concerned with outliers as to how closely the model can replicate the data it is derived from. This then begs the question, how reliable are such models at projecting forward?
No, we do not discount the outliers, fundamentally our sample may not be a true representation of the real world amongst other reasons.
Be careful Peter – these are physics based models, not regressions based on temperature curves. If they’re so deterministic why are they run in ensembles to sample the chaos space. Indeed the objective of the maligned BBC experiment was to sample the parameter space used by the climate models in a stochastic manner.
In any case the models can be and have been tested on 20th century data and paleological data sets, with some success.
How reliable are they at projecting forward. It’s a risk assessment for those professionally involved but given we don’t know how humanity will react to greenhouse gases – one can only develop “scenarios”.
So Peter, as CO2 Policy Officer on Watch then , you’d suggest that given all this model uncertainty, and as multiple lines of evidence keeping mounting, we do nothing and review when we get to 2X CO2. In the real world decisions still have to be made.
(lastly if by CSIRO and drought anomalies you mean Barrie Hunt’s work – you mean using a climate model run for 10,000 simulation years, a CSIRO retired fellow (not CSIRO) has suggested the current drought is not anomalous- how ironic – similar models to which you are uncertain ).
Ian – it’s verse 2. I assume there’s cryptic message in your message. One might guess.
Luke, physics based but still deterministic They are modelling physical data and are concerned with how well they can match their model to the data. As oppposed to stochastic type models that seek to explain the data rather than match it. I acknowledge that climate models have stochastic element within them ( many actually) however I would still describe them as fundamentally deterministic in nature.
In regards to their value when projecting forward I still contend that these models will only provide us with insights into how climate systems operate and the interconnectedness of climate variables. I don’t mean this as a critisism of climate models rather as a statement of how I view them. Compare where we are today to say 15 years ago and witness the growth in our knowledge of climate sytems, much of it derived through the insights provided by modelling. I am not anti model I just wish that people woud acknowledge their limitations and not view them as an absolute font of knowledge.
It is still very possible to create models that are mathematically correct, that can be verified and validated yet still produce nothing but rubbish. Have a look at some of the economic modelling that has done the rounds over the years. As predictive tools very few have been able to stand the test of time. My fear is that physical models, such as climate models and many others, may be heading up the same path. Especially when projecting more than 10 years ahead. The level of uncertainty surrunding such projections can be as large as the forecast or greater.
No luke I do not sugest that we do nothing. Regardless of whether a changing climate is a natural or anthropogenic phenomenon we will need to adapt to a changing cliate. I would prefer to see greater funding being put into adaptive measures and the science underpinning them as a priority.
mmmm
When you say they are modelling physical data I have to disagree – they’re modelling physics i.e. the equations of motion – which may or may not explain the observations. Get them fine enough and they will spin up their own tropical cyclones.
Yes there are some paramaterisations, internal flux corrections, and so forth but fundamentally we’re modelling physics from a basic set of principles not putting regressions through data.
Also depends whether you’re seeing them as a weather forecast or climate – i.e. the old question why can you predict climate but not the weather problem.
Initail condition versus boundary problems
http://www.mpimet.mpg.de/en/presse/faqs/wie-kann-man-klimaveraenderungen-vorhersagen.html
http://mustelid.blogspot.com/2005/04/we-cant-predict-weather-week-in.html
It’s very difficult to do good work in meteorology these days without models. i.e. with the southern annular mode for example as scientists want to see if the obs fit the model and what procsses are missing. There’s a development feedback loop in there.
We can put greater funding into adaptive measures – but why and how – on what basis if you don’t even know if it’s wetter or drier. More intense tropical cyclones or no change. Increased storm surge height or no change. The science that underpins this work is the climate scenarios
And don’t see any of these comments as sweeping arrogant rampant belief in models either – but without this technology I cannot see how we can make real progress.
Luke,
Sorry cannot agree that climate models not deterministic in nature. The almost absolute focus on ensuring that some sub models are able to precicely match CO2 and temp proxies demonstrates what I am on about. I know that they are ot the only sub models int he conglomerate that is climate modelling but they are fundamental drivers.
I also think that you may have misunderstood my “concern” with models. I am not against models as such. Indeed I use and develop models in my own work. What I am concerned about is the seemingly absolute acceptance of model output regardless of the caveats placed upon the model by those who develop them.
Models are just that, a representation of something real, that is either too large or complex to build anew or that is less well understood. I used climate models as an example(large and complex and less well understood) however it applies to all things modeled.
Given our current state of knowledge it is still not possible to “model” climate systems with the degree of accuracy and precision that experts, NGO’s, and other political types pass comment with.
OK Peter – see where you are coming from and I yield. However my defence was not so much about a definition of deterministic vs stochastic in the pure sense but moreover the representation of uncertainty at all.
Pielke made some interesting comments on this issue early last year.
.. .. .. “the representation of model uncertainty is a developing subject”.
This is an important conclusion that needs to be widely recognized by the climate community.
He identifies three currently used methods to assess uncertainty including multi-model ensembles, perturbed-parameter ensembles, and stochastic physics. Multi-model ensembles have been utilized in multi-decadal retrospective predictions, such as in the CCSP report “Temperature Trends in the Lower Atmosphere: Understanding and Reconciling Differences” . However, the use of perturbed-parameter ensembles (where uncertainties in the tunable parameters within model parameterizations are used to run the models with different values of these paramters), and stochastic physics (where the parameterizations include a statistical component) have not been completed with climate models. ”
So the whole issues of how uncertainty is represented is an area of research, as are experimental formulations of stochastic models. Some commentators have also labelled conventional climate models as quasi-deterministic.
Gentlemen and others: This has to be rough considering the time.
Data obsessions and building a model perspective using our imagination, versus some simple reality tests.
Defending old positions is a great pastime if we are going nowhere.
Peer group assessment looks nicest when we are all just out of the same mould Given that we can each be what we want to be with a little bit of mental development we can each see what we want to see in any picture at any given time.
Although our brain structure can evolve towards building an individual personality for processing external and internal events, letting the old brain free wheel gets harder with time.
Try astro travelling to the far side of the world for a better view. This probably comes best with our ability to understand others. Authors may do much better than scientists in this field. The question that must arise immediately is how much fiction does it all become in the eyes of the reader.
Our fastest mental analysing ability comes from near instant processing of our visual images. Individual vision remains our best tool for understanding both weather and climate change. Other people’s models may provide us with more insight on how we should feel about a particular observation but not the world at large.
A touch of dyslexia can help with sending a standard on its way and putting a routine on its head. It also helps with 3D jigsaw puzzles in physics and engineering.
The law however becomes an ass no mater how we chose to look at it and when was it ever truly connected with us?
Even a skilled landscape artist (and portrait painter) can be seen at times with his brush held at arm’s length, horizontally then vertically.
Desperate lab craft out in the bush comes down to spitting carefully into the palm of the hand after finding the odd ph4 buffer tablet left in the RH pocket then crushing it with stumpy screwdriver for the same pocket to calibrate a suspected wayward effluent meter below the old cheese factory.
That’s almost as effective as putting a piece of very hard to find rusty fencing wire broken at ¼ lambda measured by bare foot ½ way up Cradle Mountain strapped to a dry stick and on to the only VHF radio relay for miles around. Some volunteer carried my guestimate quickly back over his leg. That was during an invitation only “ultra” silly overland event.
Luke,
Is it possible that your BoM contacts could make another set of higher resolution version maps, this time with place names added on as per BoM “High Resolution” State Rainfall Deficiency maps that can be made now on the BoM website.
For eamples of place names see;
ftp://ftp.bom.gov.au/anon/home/ncc/www/drought/6month/colour/latest.vc.hres.gif
Warwick – I don’t have any special contacts/favours with the Bureau. The information here was a straight request to Head of Climate Analysis Section, National Climate Centre – Dr David Jones. Suggest you email David re your request and ask.
On that issue I understand they will undertake a further more detailed analysis with more stations included in coming months.
As I have said above whether it’s actually “worst” on record is somewhat complex given the varying spatial extent of different droughts, and also one should probably get away from rainfall alone into simulated river flows, or percentiles of simulated crop and/or pasture yield if you wish to integrate all the biophysical, seasonal and distribution issues missing from a straight rainfall analysis.
Warwick: I’ve been telling Jennifer on this blog for some time; we only have to look out the window to confirm BoM data like they used in your map noted above.
Have a good look a the Capital to see what’s going to drive the ideas of a few pollies on their way home too.
I hope and pray that the current “DROUGHT” will end sooner rather than latter,but should it continue, we may yet be destined to experience a looming disaster of biblical proportion.
This drought may yet inflict such a catastrophe to the equivalence of, or worse than that of a major tropical river drying up completely leaving the riverbed exposed to the mercy of extreme superheat temperatures.
At that state, only the most hardy of plants will remain even on the riverbed which means noxious weeds/creepers.
This ominous scenario may be avoided “If” we, in humility, humbly examine our ways and perhaps change direction, an exercise commonly known in the “HEAVENLY REALM as REPENTANCE”.
it wasnt helpfull
could you please give me the facts about the current drought in Australia.
your all wrong