As reported in The Age http://www.theage.com.au/news/national/a-onein1000year-drought/2006/11/07/1162661662965.html the Murray Darling Basin Commissioner, Wendy Craik,or perhaps someone else, says that current drought is the worst in 1,000 years.

How would they know? They didn't have rain gauges 1,000 years ago http://en.wikipedia.org/wiki/Rain_gauge and although the Greeks were measuring rain fall in 500 BC, it's a pretty sure bet that Australian aborigines weren't, or if they were didn't pass the records on.

This headline and story is typical of the alarmism and plain stupidity being pedalled as fact about climate by bodies anxious to escape any blame for not preparing for an entirely predictable occurrence. Yesterday I heard Mike Young (no relation) from the Wentworth Group tell Fran Kelly http://www.abc.net.au/rn/breakfast/stories/2006/1781870.htm that what we are experiencing is a "step change" back to the rainfall of the 40s and 50s.

At least he's making a point about the cyclic nature of weather, but how does he know it is a "step change" (whatever that means)? It's only 50 years back to the 50s (it's not that long ago, think Chuck Berry and "Rollover Beethoven" for example), so why wouldn't you say it was just a part of the cycle?

In the development industry we are asked to plan for once-in-a-hundred year occurrences. I've often wondered how we'd know what a once-in-a-hundred year occurrence was, because with only around one hundred years of records, our sample is too small to make a statistical assessment of the frequency of weather events.

But statistical rigour appears to be the last thing that the "experts" are worried about.

GrahamY,

How would they know indeed! I am not expert in the field, but one means of determining this may be with the aid of dendrochronological studies (tree ring growth records). I have seen no reference to this field made in support of climatic variation claims. Of course, the studies would have to relate to different regions throughout Australia to be definitive, but such could provide some insight.

An interesting aspect of dendrochronology, at least so far as Tasmania is concerned, is the peculiar characteristic of Huon pine, which contains a natural preservative. Apparently, tree ring sequences going back thousands, even tens of thousands, of years have been compiled. One would have thought that such studies would have been advanced at the forefront of this 'debate'. Whether in former millenia Huon pine grew on the offshore island of Australia, and if it did, whether any fallen log sequences lie buried in swamp or riverside locations, I do not know. But someone might.

More worrying to me is the fact that the last time I heard the term "step change" used in public discussion was in July 1987. It was used in relation to the sudden change in the election count trends on election night after there had been an interruption to the operation of TENIS (the election night information system) operated by the Australian Electoral Commission. Malcolm Mackerras had made a prediction on the basis of the early trends of a Coalition victory. Then there was the computer failure. Then there occurred the reversal of the trend. Malcolm got egg on his face. There had been a "step change" in the data. There was significant public comment by professional statisticians in following days. No definitive conclusion was reached.

Could all this "alarmism and plain stupidity" be nothing more than a backdrop being set in place to make believable dramatic changes in voting patterns at upcoming elections in Australia, and perhaps elsewhere? Dendrochronologists! To the front, quick march!

the structure of our political society precludes longterm planning. if environmental questions force themselves onto the agenda, these questions will be dealt with by buckpassing and ad hoc 'solutions'.

it is very amusing to watch politicians attempting to survive and prosper in situations they are utterly unfit to cope with, but dont laugh too loud- it's your nation they are buggering up. i say 'your' in the relational sense, as a sheep to it's paddock. in the possessive sense, it's not yours at all, it's theirs.

since australians are a subject race, unable to direct the destiny of their nation, or even conceive of the utility of doing so, all discussion of this question, and every other, will in the end be no more than "somebody (else) should do something."

Calling the current lack of water a 1000 year drought assumes that normal rainfall will resume some time soon. In the last 60 years we have changed the face of Australia by

- deforestation eg in 1939 95% of Victoria was forested

- hydroelectricity, irrigation and flood mitigation schemes

- syphoning Darling River water into Cubby station.

In primary school we all learnt the rain cycle of
- water vapour forms over the ocean
- moves over land and collects more water vapour from the CO2 given off by the trees
- moves over the mountians and falls as rain.

In the last 60 years the population has trebled, houses have got bigger and each dwelling houses less people - so the land devoted to housing might be 10 times as much as 60 years ago.

Urban areas are warmer than rural areas. Rain forests are 5 degrees cooler than cleared farmland.

By deforestation and urbanisation we have made Australia hotter and drier.

We, the Australian people - not the market - need to decide what crops need to be grown under irrigation, which land should be taken out of agriculture and do it fast.

Forrest, my understanding is that reconstructions of climate using cores in the Great Barrier Reef suggest that we have seen worse droughts before we Anglos settled here than since. Not that this provides evidence of what may have happened in the Murray Darling.

But you don't have to go back that far to check the MDBC claims. Jennifer Marohasy has kindly placed a graph on her site using Bureau of Meteorology figures which show Murray River flows haven't changed too much in the last 100 years, and in fact on a rolling average appear to have been trending upwards. You can view the whole of her post at http://www.jennifermarohasy.com/blog/archives/001719.html

What I can't understand is why journalists, who are normally quick to sniff a conspiracy, have lost their sense of smell on this one.

Graham_Y are you suggesting the the shortage of water in the Murray_Darling Basin isn't so much attributable to drier weather but more to increased irrigation extracting more water from the system?

Does this mean we really do have to compulsorily acquire Cubby Station, and ban rice and cotton farming in the Murray-Darling?

Or do we decide to allow our dairy product, orchard fruit and market garden vegtables to be imported from New Zealand, China and Thailand.

The body language of the Victorian minister for the Environment standing behind the Premier suggested he was not happy