Rainfall patterns

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.

Plotting as a histogram with the rain fall amounts along the bottom axis we get this:

SE AU rain histogram
Which can be seen to be fairly skewed. A few high results boosting the average in later years.

What exactly it shows is difficult to assess. Certainly we can see that the recent drought years haven’t been particularly severe given the entire history, with only one year outside 1 Standard devation (100mm) from the mean of 603mm. In the first half of last century, such rainfall would have been typical or even good.

I find it somewhat comforting to see that unlike the temperature charts, which do show a clear upward trend the rainfall at least hasn’t become abnormal, at least yet.

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35 Responses to Rainfall patterns

  1. steve m says:

    The theory that rainfall is declining in the south of WA is also interesting http://www.abc.net.au/science/news/enviro/EnviroRepublish_946924.htm

    The Wimmera, my area of origin, is bone dry and has been for 10 years. Dozens of Wimmera lakes have been dry for years eg Green Lake, Natimuk Lake, Edenhope Lake, Pine Lake, Dock Lake etc etc.

    Maybe looking at rainfall for a large area like “South East Australia” won’t pick up regional effects of global warming. Higher temps may also mean greater evaporation. From what I can gather, total rainfall in Australia may increase a little due to global warming but some areas will become drier.

  2. Steve says:

    Steve,

    yes It certainly doesn’t reflect the regional variability, and I would have to ask has that happenned before in the historical record? Also if it is occuring when the average hasn’;t gone down that much is it occuring because some areas (say coastal) are getting more rain and more inland areas like the wimera getting less, or is it just the random variability that we always see. And yes more rain fall plus more evaporation is of course an issue, particularly in that it may change the suitability for farming in different regions.

    Certainly when you look at the temperature trends it looks clear that the warming we are experiencing is both real and a break from anything experienced in the past 100 years. I don’t think its so clear with the rainfall. Sure its less over the last 20 years than the previous 30-40 years, but was that just an unusually rainy period. That’s what it appears to be from the data.

    Perhaps the last 20 years are the begginings of something, and certainly its what many models predict, but it doesn’t seem that you can clearly see it in the data yet. Perhaps if you delve deeper into shifting patterns say more summer and less winter rain you can see something or more coastal and less inland rain.

    My interest in this is to try to get a handle on what is unlikely or not. There is nothing that irks me more than the sort of news reporting that goes along the lines of “is this hot weather due to global warming?” often if you look at the historical record it may not even be all that exceptional.

    I remember talking to Karl Kruszelnicki once who said (from memory) that everytime we got weather up near 40 deg he’d get some journalist ring him up and ask him if this was due to global warming, and he’d tell them it was due to summer. The correct answer of course is probably that its 99.5% due to summer and 0.5% due to global warming, but try explaining that to a journalist.

  3. steve m says:

    “There is nothing that irks me more than the sort of news reporting that goes along the lines of “is this hot weather due to global warming?” ”

    I agree, Steve. Well, sort of. I’m probably a little bit more annoyed when some RWDB media pundit, or someone like Jennifer Marohasy at the IPA, cite an example of unusually cold weather to cast doubt on AGW.

    People in the Wimmera say the current dry is unprecedented, but of course they are only talking about the time since European settlement. I’m not convinced “beyond all reasonable doubt” that the dryness in the Wimmera is a result of AGW. All I am willing to say at this stage is that it is “possible” and “consistent with CSIRO predictions”.

    Are you aware of the CSIRO regional predictions on climate change? The one for the Wimmera is here http://www.greenhouse.vic.gov.au/impacts/media/Wimmera.pdf#search=%22csiro%20rainfall%20patterns%20wimmera%22 and says “Future climate in the Wimmera is expected to be warmer and drier than it is presently”.

    Cheers.

  4. Steve says:

    Yes the reverse is just as stupid.

    Thanks for the link.

  5. graemebird says:

    “While I accept and indeed am concerned about the prospect of global warming….”

    Do you accept and are you concerned about global cooling?

    “While I accept and indeed am concerned about the prospect of global warming….”

    Why?

    You’ve always been particularly mindless on this issue.

    And the last time you stooped to answer you had nothing. Said you were putting your trust in stupid computer programs that didn’t backtest and didn’t include a solar forecast.

    “While I accept and indeed am concerned about the prospect of global warming….”

    Why?

    Please.

    Show me that you are not just a complete Zombie.

    Just one of Marks useful idiots.

  6. graemebird says:

    “I agree, Steve. Well, sort of. I’m probably a little bit more annoyed when some RWDB media pundit, or someone like Jennifer Marohasy at the IPA, cite an example of unusually cold weather to cast doubt on AGW.”

    WELL IT DOES CAST DOUBT ON THE LIKELIHOOD OF CATASTROPHIC WARMING.

    And lets be very clear about this.

    The alarmists put an inordinate amount of emphasis on CO2 levels.

    They downplay the solar oscillations. They say that since the watts per metre squared typically vary less the 1% then the suns variations cannot be driving the process.

    So they say for practical purposes, it is the CO2 level that is driving the process.

    Its a ridiculous theory but nevermind its their theory.

    And you bet all these cold snaps and the ocean temperatures falling away since 2003 is evidence against this theory.

    There hasn’t been much evidence FOR this theory for very long time but never mind.

    The fact is that the cooling oceans and cold weather is very much evidence against the alarmists.

    JUST HOW!!!!!!! GULLIBLE ARE YOU FELLA???

    By Allah this fraud has you all acting like zombies.

  7. Steve says:

    Bird,

    I’ve been busy moving, but what happened? I thought you thought warming was occuring and it was a good thing.

  8. graemebird says:

    Thats right.

    That would be my best guess.

    But there is little doubt that we will get colder by mid-century if we include a solar forecast.

    That the IPCC did not include a solar forecast shows them to be the frauds they obviously are.

    But lets not get diverted Edney.

    You have some explaining to do. You have a special responsibility not to lead the public astray. Since they are likely to believe you Physics degree gives you some sort of special insight.

    Apparently not.

    So lets go again:

    Where is your evidence for the likelihood of catastrophic global warming?

    Why are you buying into this fraud in the first place and given that we have mountains of evidence for the likelihood of catastrophic global COOLING but none for the likelihood of catastrophic global WARMING……

    ……then why are you goosestepping along to the tune of the bullshit momentum rather then helping me bring it to an end and get those coal-fired plants up and running.

    I could use a little help.

    This is a serious crisis we have on our hands. A serious socialist-inspired energy-crisis.

  9. graemebird says:

    Fantastic Edney.

    You’ve got me on moderation.

    Bravo.

    You are now entering the Green lunatic fringe.

  10. Steve says:

    Bird, I don’t have you on moderation, the spam filter caught one comment. Calm down.

  11. Sacha says:

    Birdy – be unflappable!

  12. Sacha says:

    Here is a link: http://www.csiro.au/csiro/content/standard/pps7u.html about the Regional Impacts of climate change in Australia.

    Of course it’s suspect as it’s no doubt prepared by “dumb science workers”, but you have to work with what’s around.

  13. graemebird says:

    “Bird, I don’t have you on moderation, the spam filter caught one comment. Calm down.”

    Yeah will stop filibustering Steve.

    I’m after actual answers not content-free comebacks.

    Sacha.

    Don’t make links unless they have actual evidence.

    Where is the evidence?

    Its not there is it Sacha.

    No it isn’t.

  14. graemebird says:

    So Steve.

    I asked some questions. And over a period of months you have studiously avoided giving me sensible answers…

    WHAT IS THIS TELLING YOU?

    Sacha. You thought or pretended to think you made a link that contained some evidence…. But it doesn’t contain any such evidence…. so…

    WHAT IS THIS TELLING YOU?

    Its very easy to tell who would have been the “GOOD GERMANS” if they were living in Germany in the 30’s.

    Its the likes of you that are so easily influenced by bulldust-momentum.

  15. graemebird says:

    Come on Sasha?

    Why the wild goose chase.

    Just shows how interested you are in the truth.

    NOT AT FUCKING ALL AND WHATS WRONG WITH YOU.

    There was absolutlely nothing there. Not even any unbacked assertions.

    Now Steve since Sacha and you have tried to dodge and filibuster and distract we have to go through it agains and this time attempt not to be dishonest:

    “Where is your evidence for the likelihood of catastrophic global warming?

    Why are you buying into this fraud in the first place and given that we have mountains of evidence for the likelihood of catastrophic global COOLING but none for the likelihood of catastrophic global WARMING……

    ……then why are you goosestepping along to the tune of the bullshit momentum rather then helping me bring it to an end and get those coal-fired plants up and running.”

    Lets have a proper comeback HEY!!!????

    Is that too much to ask to get a real explanation. Or some real evidence. As opposed to a mindless distraction from Sacha or a fob-off from you???

    I don’t think thats too much to ask.

  16. Sacha says:

    Bird, I can’t speak for Steve but I work and so don’t have a lot of free time. Subsequently, I don’t have the time nor energy to obtain sufficient evidence and do the appropriate analyses to come to an independent view about many things – I’m in the same boat as everyone else, including yourself.

    In fact, the amount of “stuff” that I am completely sure about and that I have independently verified is pretty small – and this would be true for everyone.

    If you’re so convinced that you’re correct about something which almost everyone else is wrong about, publish the evidence and analysis to support your ideas. Be prepared for people to ask questions and don’t just reflexively react.

    Until you do, everyone will rightly ignore.

  17. Sacha says:

    Bird said:
    “Sacha. You thought or pretended to think you made a link that contained some evidence…. But it doesn’t contain any such evidence…. so…

    WHAT IS THIS TELLING YOU?

    Its very easy to tell who would have been the “GOOD GERMANS” if they were living in Germany in the 30’s.

    Its the likes of you that are so easily influenced by bulldust-momentum.”

    If I recall correctly, the link is to a press release talking about the results of work done. Tell me Bird, you’d be the only one who resists the “bulldust-momentum”, wouldn’t you, while all the dumb idiots are fooled?

    Do you know what a good scientist does? They say to themselves: “this could be wrong – what is actually happening here?” They are open-minded to the possibility of being wrong. I havn’t picked this idea up in anything you’ve written.

  18. graemebird says:

    “If I recall correctly, the link is to a press release talking about the results of work done.”

    Right. No evidence.

    Do you see a pattern here? A good scientist would look for a pattern. A good mathematician would look for pattern recognition.

    Now have you got some evidence for the likelihood of catastrophic warming or not?

    IF IT WAS ACTUALLY THERE YOU WOULD HAVE IT AND COULD FIND IT.

    Or are you just going to come up with some make-believe-evidence for a distraction.

    Surely if there was evidence for warming reducing rainfall (the opposite of the case actually Mr Wrongway Corrigan) surely the CSIRO wouldn’t simply present it.

    Your failure to link evidence results from there being no evidence.

    WHAT ABOUT YOU MUNN.

    YOU GOING TO EXPLAIN YOURSELF?

    OR YOU GOING TO GO QUIET FOR A WEEK OR TWO AND FALL BACK IN LINE WITH THE GOOSTEPPING CROWD AGAIN?

  19. graemebird says:

    IS IT TOO MUCH TO ASK FOR THE TWO OF YOU TO ATTEMPT TO ACT LIKE SCIENTISTS.

    For fucksakes people this is just a disgrace. Both of you nutters have PHD’s.

    You got them largely off the public tit so can I simply ask you to act like responsible adults and attempt to show the victims (the taxpayer) some sort of respect here.

  20. graemebird says:

    Dammit Edney. I got mixed up between you and Munn.

    That shows the extent of your back-sliding.

  21. Steve says:

    Bird,

    As Sacha says, I am busy and don’t have time to go through every detail of AGW theory or (particularly at the moment) join a lengthy argument. However I have read some on it and I find that in general the mainstream account that the release of CO2 is going to increase the average global temperatures is more convincing than the objections I have read.

    While I agree that cooling would be a problem if it occurred, I am not at all convinced that at the current time that cooling is likely,

    As far as I can tell my main difference of opinion with you is that:
    1) the risk of cooling is unlikely in the near future.
    2) warming is likely and will be bad

    I will conceed that I have uncertainty about how bad it will be but feel that it will be, overall, a bad thing with a small chance it will be very bad. Human settlement is in a fair part guided by climatic conditions. Were these to change it will in the majority of cases be for the worse – settlement will be less optimal as rainfall patterns and climatic belts etc shift.

    With that in mind I think that some warming is inevitable and we will cope (with some effort) with a couple of degrees warming, however we should be taking measures to curb emissions in an effort to ensure that the chance, even if its small, of worst case scenarios being reduced

  22. Sacha says:

    I broadly agree with Steve’s thoughts in his last comment. The problem is about dealing with a potential catastrophic risk.

    Bird, it’s a waste of my energy to respond seriously to your comments.

    A very important point is Newton’s as follows: (From Wikipedia) Isaac Newton famously remarked in a letter to his rival Robert Hooke dated February 5, 1676 that:

    “What Des-Cartes did was a good step. You have added much several ways, and especially in taking the colours of thin plates into philosophical consideration. If I have seen a little further it is by standing on the shoulders of Giants.”

    Bird, everyone relies on previous work – it is not possible to a single person to construct a complete theory of mathematics, physics and chemistry as one doesn’t have enough time nor resources to do it. Thus we rely on others and have to extend some trust to previous work that we deem reliable, although we’re always aware that it could be wrong.

    I doubt that you understand all pertinent aspects of atmospheric chemistry without having referred to other people’s work. I doubt that you fully understand the carbon dioxide molecule without a good grasp of quantum mechanics, which also requires a good grasp of university level mathematics. Thus you are relying on other people’s work.

    This is tiresome and I won’t respond anymore.

  23. graemebird says:

    “As far as I can tell my main difference of opinion with you is that:
    1) the risk of cooling is unlikely in the near future.
    2) warming is likely and will be bad”

    This is just an assertion. And its a FALSE assertion. There is no evidence for this.

    WHERE IS THE EVIDENCE SACHA.

    WHERE IS THE EVIDENCE.

    YOU GUYS ARE JUST MINDLESS.

    Is it too much to ask that you people act with a bit of intellectual honesty?

    Attempt to be fucking scientists will you. Now you both have PHD’s.

    This is pathetic.

  24. graemebird says:

    You know if this wasn’t a big fat fucking fraud it would just be a matter of you guys showing me the evidence.

    They are doing such a bad job when it comes to education these days.

    DO YOU ADMIT YOU HAVE NO EVIDENCE AT ALL FOR THE LIKELIHOOD OF CATASTROPHIC GLOBAL WARMING!!!!!

    Will you further admit that there is mountains of evidence for the likelihood of catastrophic global COOLING.

    If not why are you being dishonest.

    If so what are you being dishonest and goose-stepping in line with this scientific fraud.

    You guys aren’t real smart are you.

    Now Sacha. No distractions or poopy-pants behaviour.

    This time lets see some evidence.

    Go!!!!

  25. graemebird says:

    Look Edney.

    I don’t CARE for you pointing out where we disagree. Thats not what we need from you.

    What we need is evidence for your own position.

    I know you disagree. We wouldn’t be discussing this if we both agreed.

    For relevance it would have been better just to tell me what you had for lunch.

    Now you are helping along this guild-of-thieves fraud and there must be some reason for it.

    You must have some evidence somewhere for it or you are doing the wrong thing.

    So lets see the evidence for the likelihood of catastrophic global warming.

  26. Steve says:

    DO YOU ADMIT YOU HAVE NO EVIDENCE AT ALL FOR THE LIKELIHOOD OF CATASTROPHIC GLOBAL WARMING!!!!!

    Will you further admit that there is mountains of evidence for the likelihood of catastrophic global COOLING.

    No I won’t.

    The evidence is bird. CO2 traps heat (absorbs infrared). CO2 concentrations in the atmosphere have been rising as a result of buring fossil fuels and other activity. As expected global mean temperatures have been rising.

    The exact link is of course complicated due to positive and negative feedbacks. We have models to help us with this. While not perfect, due to their complexity, they are our best estimates incorporating all the known evidence and indicate significant amounts of warming.

    On the other hand global cooling theory is based on what?

  27. graemebird says:

    Not only are they not perfect.

    THEY DON’T BACKTEST YOU MORON.

    They don’t backtest so they are not evidence.

    You have not evidence.

    Now that you have failed again to come up with any evidence for the likelihood of catastrophic global warming will you now admit that you have no evidence.

  28. graemebird says:

    The evidence for the likelihood of catastrophic global cooling is mountainous. And it consists of the last 39 million years of earth history imbedded in the geological and fossil record.

    But its really the last 3 and a half million year record from the time when the Isthmus of Panama fused with North America.

    Since then we have spend 80-90% of that intervening time under ice.

    WE ARE IN A FUCKING ICE AGE STEVE.

    THE WORST FUCKING ICE AGE IN MORE THEN HALF A BILLION YEARS.

    Now can you attempt not to be an idiot and admit you have no evidence.

    Show me one of your models for example that includes a solar forecast.

    Its a sick joke Steve and you are acting like an idiot.

  29. graemebird says:

    SO YOU WERE BASING YOUR EVIDENCE ON COMPUTER MODELS THAT DON’T BACKTEST AND DON’T HAVE A SOLAR FORECAST.

    Now will you admit that you have no evidence for the likelihood of catastrophic warming.

    Fucking admit it you dishonest bastard.

    Whats the fuking matter with you?

  30. Steve says:

    So what is your solar forecast graeme? According to these guys we are in an exceptionally long interglacial. http://www.sciencemag.org/cgi/content/summary/297/5585/1287 and don’t have to worry for another 50k years.

  31. graemebird says:

    No we are not according to those guys.

    Thats bullshit.

    According to those guys its POSSIBLE that we could be but they don’t offer any evidence for such a thing.

    So you have tendentiously misinterpreted what they have said.

    Also its more likely that without human intervention Chicago would be 1km under ice within 2000-4000 years.

    But in any case do you have any POSTIVE evidence for the likelihood of catastrophic warming?

    Lets not get distracted by dishonesty bullshit or anything else.

    Lets see some evidence fot the likelihood of catastrophic warming.

    Or an admission that you don’t have it.

  32. graemebird says:

    “An Exceptionally Long Interglacial Ahead?”

    How did I know you were bullshitting. Thats a question mark dopey. And their evidence is unbelievably weak.

    But its hopeful.

    Now…….

    Since you have distracted me with this dishonesty we have to get back on track:

    “SO YOU WERE BASING YOUR EVIDENCE ON COMPUTER MODELS THAT DON’T BACKTEST AND DON’T HAVE A SOLAR FORECAST.

    Now will you admit that you have no evidence for the likelihood of catastrophic warming.

    Fucking admit it you dishonest bastard.

    Whats the fuking matter with you?”

  33. graemebird says:

    Have you or Sacha found that evidence for the likelihood of catastrophic global warming yet?

    You sure sounded like you’d found it over at catallaxy?

  34. milly says:

    hello my name is milly

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