More on rainfall

15 March, 2007

For those unconvinced about my previous claim that, according to the BOM data, there doesn’t appear to be a drying trend on the east coast and think it might be an artifice of too broad averaging, I note that they should have a look at the trend maps found here. For example the rainfall trends from from 1900 to 2006.
Australian Rainfall trend 1900 - 2006

This shows few regions which have shown a definite drying trend over the period. One clear exception being the south west of WA, which does show a drying trend over pretty much anytime period you pick. In addition it appears that some slight trend could be evident in mid to northern Queensland.

Go and have a look at some of the different time periods on their site, the lack of a clear trend for much of eastern Australia isn’t just for the period 1900-2006. In case any one’s concerned that its because we started the comparison in a drought. Take 1910-2006, 1920-2006 or 1930-2006 and you get something similar.

Indeed its not unless you compare with the 1950’s to 1970’s that you get a really marked decrease in rainfall in most of Eastern Australia.

Drying up or typical climatic variation?

10 March, 2007

I noticed this article Big dry: no one knows why in the SMH this week, and in particular the claim that eastern Australia’s rainfall had dried up since the 1950’s. The report seems to be related to this press release announcing a new centre at UNSW studying climate change.

A priority for the new centre is to better understand the mystery of why Australia’s most populated region, the continent’s east coast, has suffered such major declines in rainfall in recent decades.

“We recently had a round-table of Australia’s leading climate-change researchers and this emerged as the biggest unknown issue and, of course, it seriously affects the largest concentration of people stretching right down the coast from Cairns to Melbourne,” Professor England said.

So I had a look again at the rainfall graphs and time series provided by the Bureau of Meteorology for eastern Australia and there is no doubt that we have been receiving less rainfall in recent decades than the 1950’s. However it also seems that we are receiving more rainfall than in the first half of the 20th century, so the question seems to me to be as much why did rainfall rise in the 50’s as why has in fallen in the 80’s and 90’s.

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Confusion over water trading

9 November, 2006

Tucked away at the bottom of this article about Australia taking up nuclear power is this bizarre statement about water trading which kind of demonstrates why people should think carefully before commenting outside their area of expertise.

Water and irrigation experts remain unsure about whether any of the measures decided on at Tuesday’s meeting of state and Commonwealth leaders would free extra water.

Peter Schwerdtfeger, emeritus professor of meteorology at Flinders University’s Airborne Research Centre, said he agreed that overallocation of water needed to be stopped, but with “precious little else” that the meeting decided on.

“Water trading as it stands now is an evil nonsense. It has allowed the fallacious belief to develop that water can be sold either upstream or downstream without any consequences.

“Water that is sold to NSW will not flow downstream and the bed of the Murray may dry out. It is not environmentally or economically viable.

“Water trading only works if you have a surplus of water … why don’t we encourage people to use water more efficiently?”

It could be that Prof. Schwerdtfeger has been taken out of context or misquoted, but it seems more likely that he doesn’t understand the basic point that trade, by putting a market price on water it implicitly results in it being put to the most more efficient uses.

I don’t think that anyone is under the illusion that water is a commodity that can be traded “without any consequences”. Environmental flows must be maintained, losses when trades occur over long distances and such are all issues, but hardly irreconcilable ones. Most importantly is trading is more important when there is scarcity, its barely necessary if you have surplus. Prof. Schwerdtfeger may be an expert in climatology, but when he’s talking about trading, I don’t think he has a clue.

Rainfall patterns

4 October, 2006

While I accept and indeed am concerned about the prospect of global warming, I’ve always been a little bit sceptical of the claim that it will make Australia drier. Naively I expect that if it gets more tropical we’ll get more rain. I also accept that there are many other things happening which may confound this trend. Anyhow I notice via John Quiggin this BOM site, giving maps and time series of annual, monthly etc rainfall for Australia and various other regional breakdowns. John seems to have picked out a graph which makes the browning, appear particularly severe, but is it really so?

Too often we are just presented with just the trend, and without knowledge of the variability over time, how any particular result fits in is difficult to understand. For example if we plot the South Eastern Australia average rainfall for the last 100 years we get this
SE Australia annual rainfall

The obvious things to note is that the average for the first 50 years was well below the later part of the graph. Indeed by the standards of the first half of last century recent drought years with the exception of 2002 haven’t been particularly severe. Instead most have been above the average rainfall experienced in the first half of last century.

If we take the years to 1950, we find an average rainfall of 575mm, for the remaining 55 years the average is 625, with the five highest rainfall measurements all falling in the same half of the graph.
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The environmental damage of agricultural subsidies

5 August, 2006

When discussing the need for dropping tariffs and other subsidies for agriculture, its common to make arguments along the lines of the fact that it makes prices cheaper for consumers and helps third world farmers enter first world markets and so eases poverty. Rarely though have I seen it argued that agricultural price subsidies massively increase usage of fertilizer and pesticides.

Now obviously if you are directly subsidising those inputs then usage will go up. A bit more subtle is the the point that if you are supporting the end price of the product that usage can go up massively. Here is Tim Harford in an interview

So you have got acres of fertile land in Guatemala that you could grow sugar there. But because of protectionism, the sugar is grown in Florida and the Everglades are destroyed. And meanwhile the Guatemalans are either growing coffee for basically nothing, or like the Columbians, they think, well, maybe we should grow cocaine instead.

Now this is not a good idea. And I have a little graph — I don’t have a lot of graphs in my book. I prefer the written word. But sometimes the picture is worth 1,000 words — and it’s just a graph of trade barriers for different countries and how much fertilizer they use on their agricultural land. The countries that have the highest trade barriers, Japan and Korea use so much fertilizer. Then it is the EU. They use a lot. American less, but you know they still have quite a lot of protectionism and they still use quite a lot of fertilizer.

Once you think about it its obvious. If prices are made higher then people will farm more marginal land. The land is marginal for some reason, soil infertility, pests or perhaps poor water supply requiring more external inputs to be usable. Additional land will be cleared for this purpose. Not only that but even productive land will be pushed that much harder. More fertilizer, more pesticides and additional water brought in to raise every bit extra yield. Because these additional inputs are necessarily much less productive, otherwise they would be done anyway, they naturally have much greater effect on the surrounding environment compared with the additional yield they bring.
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The man with no spine

1 August, 2006

Morris Iemma announces “we’ve assumed that the people are not ready for drinking recycled water“. So rather than take a position himself, he’s assumed that the people of Sydney won’t do it and gone on his merry way with out having to take a position or make a stand of his own. Heaven forbid a referendum where you might actually have to stand for some side of the issue.

If there is a gutless way to weasel out of a making any hard choice you can guarantee that Morris Iemma will be there, sneaking away.

Toowoomba rejects recycled water

30 July, 2006

Unfortunately it seems that the scare campaign has won and the residents of Toowoomba have rejected the proposed recycling of sewage into their drinking supply with 61.6% voting no in yesterday’s referendum.

If this was just the residents of Toowoomba rejecting the most sensible option for dealing with their own problems then I would be inclined to say so what. However given the nature of politics and politicians this will be viewed as a test case for how other communities will react to such a plan and no doubt there will be others silently backing away from recycling proposals. As I mentioned in an earlier post, Sydney could quite cheaply use recycled water for about about 9% of its water usage, but even this modest amount was rejected in favour of the single big ticket solution of desalination.

Of course for non-coastal areas desalination is not even an option so somewhere along the line people are going to have to realise that in the driest continent on earth we are going to have to be a little more sensible about how we reuse our water. The only other option long term is to go for the sort of population cap that some Green groups would propose. Rejecting this is merely the residents sticking their heads in the sand and hoping their problems go away or someone else solves it for them.