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The Queensland floods

Posted on 12 January 2011 by John Cook

As the Queensland floods have now hit Brisbane, a number of people have emailed or posted comments enquiring about our well-being. Many thanks to everyone for their thoughts and concern. I'm happy to say the Cook family is safe and dry - we happen to be located in a relatively elevated area (not by design - extreme flooding was not even on my radar when we moved into the area). However, many nearby suburbs have not been so fortunate.

Ten minutes south-east from us, low-lying areas of Strathpine were evacuated yesterday. South Pine River has burst its banks and covers a large portion of the suburb:

Meanwhile, to the north-west of us, just down the road from our church, One Mile Creek has also burst its banks and blocked off the road:

Up to 40,000 homes are estimated to be affected by flooding over the next day, when the Brisbane River peaks at 3am tomorrow morning. But while the flood waters rise gradually here, incredible scenes were witnessed earlier this week in the town of Toowomba, 90 minutes west of Brisbane. The media are refering to it as an inland tsunami - a wall of water rushed through the town, dragging along cars, shipping containers and even houses. We heard accounts of entire homes being plucked off their foundations and carried by the waters, with people inside crying out for help. The tragedies this and other Queensland towns have endured are heartbreaking and the damage mindboggling.

When these kind of extreme events happen, people ask "Did global warming cause this flood?" as if the answer should be yes or no. It's more appropriate to ask does global warming have an effect on these types of events? The scientific evidence indicates yes. As temperatures have risen, we've observed more water vapour in the air. More water vapour leads to more extreme rain events. Over the last few decades, we've observed an increase in the number of extreme precipitation events. And we expect the number of extreme precipitation and flooding events to increase as global warming continues.

It's times like this that I can't help thinking of the words of NOAA scientist Deke Arndt, "Climate trains the boxer but weather throws the punches". Weather will always throw these random punches at us. Occasionally it gets in a lucky punch that knocks us off our feet. But what we're doing is training weather to throw harder punches at us and more often. That's what is being observed and that's what we expect to see more of in the future.

Anyone who wishes to help, you can Donate to the Queensland Government's flood relief appeal.

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Comments 1 to 50 out of 84:

  1. Glad to hear you and your family are ok John.
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  2. i'm glad you are ok John and i thought about you when i saw this on the news (you being the only "bloke" i know in that country). stay safe.

    it seems that climate scientists are suffering in the media from conflicting messages and predictions. every weather event from floods to blizzards are being blamed on global warming. a few years ago the news i heard was the global warming would cause drought, not massive rains.
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    Response: Global warming leads to an intensification of the water cycle. Drought severity is increasing in some regions and extreme precipitation is increasing in other regions. These are not merely predictions - an increase in drought severity and extreme precipitation have both been observed.
  3. John, it's good to hear you and your family are safe on higher ground. I hope things are not too difficult for you. I know there are power outages, phone outages, disruptions to transport and grocery shops sold out or closed from flooding.

    Today climate specialist Professor David Karoly, on ABC News 24 television, said quite clearly that because the oceans are progressively warming as a consequence of human induced global warming, the strong La Nina is stronger than it would otherwise be. From what I can research looking at flood history of Queensland, larger flood events are occurring more often as is the intensity of precipitation wherever it occurs in Australia (down in the south eastern Australia as well as further north).

    BTW I hope this does not conflict with comments policy, but anyone who wants to help could donate here:
    http://www.qld.gov.au/floods/donate.html
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    Response: Thanks for the reminder re the donation link - will add it to the main article.
  4. @ garythompson #2 - flood and drought are not mutually exclusive. You are correct regarding drought predictions for Australia but you might have missed the predictions of record rain events as the higher levels of water in the atmosphere fall as rain.

    What you may not know is that Australia has suffered extensive drought of extremely long duration and record high temperatures over the past decade. Only a couple of years ago (or less?) the Brisbane water supplies were as low as 16%. Now they are at almost 200% stated capacity, even though the flood mitigation section of the Wivenhoe Dam was emptied in preparation for the current wet season.

    When it rains it rains more intensely. Many parts of Australia have had unprecedented rain intensity with this summer's La Nina, causing major flooding in Victoria, New South Wales, north west Western Australia and Queensland. This intense rain follows years of drought.
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  5. Hi John, I did not know that you were a fellow Brisburnian. I'm glad to here that you are safe.

    garythompson @2, the CSIRO has been predicting since at least 2003 that the main effect of global warming on subtropical Queensland and NSW would be longer, hotter, and drier droughts, BUT that when rains came it would be more likely to flood, and to flood more severely (check my blog for links).

    The reason that global warming will increase the duration of droughts is because it makes it more likely that any given year will be an El Nino year, and El Nino years bring droughts to Australia. It will be drier because it is hotter, which results in more evaporation of moisture stored in the soil.

    Of course, though it is more likely that any given year will be an El Nino year, La Nina's can still occur, and strong La Nina's bring floods. Hence the current flood. The reason global warming results in more rain when it floods is because warmer Sea Surface Temperatures (currently at a record level in Australian Waters). Warmer sea surfaces means more evaporation, which in turn means more rainfall.

    Knowing this, it was no surprise to me that the ten year drought we have recently been through was broken by record breaking floods in Queensland in March, with that record now in turn shattered.

    Brisbane's highest levels of flooding all occured in the 19th century, with river peaks up to 4 meters above what is currently expected. What has changed since the 19th century was the construction of the Summerset Dam which provided for a large measure of flood mitigation. That couldn't prevent '74, so they built the Wivenhoe Dam with an even greater capacity for flood mitigation, and greatly enhanced Brisbane's drainage system. These have greatly helped us, for without them floods in Brisbane would have hit '74 levels last week, well before Toowoomba's "instant inland tsunami". It has still not been enough.

    What nobody is yet commenting about is that Brisbane's previous episodes of mass flooding have been the result of cyclone remnants hitting Brisbane after a preceding season of massive rainfall. This time we have had the preceding season of rainfall, but no cyclone remnant. Absent global warming, Brisbane would probably only be experiencing minor flooding now, but global warming has been a game changer in the amount of rainfall we can expect from a normal rain depression.
    http://bybrisbanewaters.blogspot.com/2011/01/under-brisbane-waters.html
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  6. sout @4, I believe it was November of 2009 that the drought broke in Brisbane with rains that restored Wivenhoe to capacity within a week or so. For comparison, in just 24 hours yesterday Wivenhoes stored water increases by 40% of rated storage capacity whilst letting enough water through its floodgates to cause lead to the expected '74 plus level floods in Brisbane tomorrow. Its maximum capacity is 220% of its normal storage capacity to allow for flood mitigation. Last I heard, it was at 175% of normal storage capacity, or one more days rain had it not (very thankfully) relented.
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  7. As an addendum, the drought is still continuing in the South West of West Australia (around its capital) with dams at 30% of capacity, and 15 - 20% of Perth's water coming from desalination.
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  8. As a further addendum, much (most) of Victoria in south eastern Australia has suffered drought for the last decade or more. It is expected to continue to get warmer and drier in Victoria as global warming progresses. A desalination plant is under construction to provide Melbourne with improved water security.

    Melbourne water storage is currently at 53.7% capacity gaining about 300 gigalitres since June 2010 (about twice the water of 2009 but only a bit more than half the amount of water held in storage in 1997). Yet across the state and in Melbourne this summer we've had a lot of rain, record precipitation events and major floods with this season's La Nina.

    http://www.melbournewater.com.au/content/water_storages/water_report/zoom_graph.asp

    A lot of people are commenting on the 'cool' summer. But it only feels cool by comparison with the record heat of recent years. In actual fact, the mean monthly maxima and minima for Melbourne this summer are still above 30 year averages (including the 1981 to 2010 average). Compare recent months in Melbourne here (scroll down for links to recent months):

    http://www.bom.gov.au/climate/dwo/IDCJDW3050.latest.shtml

    With monthly averages here (you can select the period):
    http://www.bom.gov.au/climate/averages/tables/cw_086071.shtml

    Melbourne and Victoria are not the world and therefore that data on its own does not allow inferences to be drawn about what is happening at a global level. Nevertheless what's happening here in Victoria does illustrate the local climate change that is already occurring, in line with what Australian scientists have been telling us will happen with global warming.
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  9. Hi John,

    Fingers crossed-- glad to hear that you are coping.

    Just to add to your comments above. From Dai, Trenberth and Qian (2004) concluded that:

    "From 1950 to 2002, precipitation increases over Argentina, the southern United States, and most of western Australia resulted in wetter conditions (i.e., higher PDSI) in these regions. However, most of Eurasia, Africa, Canada, Alaska, and eastern Australia became drier from 1950 to 2002, partly because of large surface warming since 1950 over these regions".

    And

    "During the last two–three decades, there was a tendency of more extreme (either very dry or very wet) conditions over many regions, including the United States, Europe, east Asia, southern Africa, and the Sahel."

    The recent deluges of rain over Queensland are, in part, related to the current La Nina, with the heavy rains likely being exacerbated by the record high SSTs surrounding Australia and attendant increase in water vapour content in the atmosphere.

    The increase in precipitation and weather extremes is consistent with a warming planet and accelerating hydrological cycle. To quote Trenberth:

    "Because one of the opening statements, which I’m sure you’ve probably heard is “Well you can’t attribute a single event to climate change.” But there is a systematic influence on all of these weather events now-a-days because of the fact that there is this extra water vapor lurking around in the atmosphere than there used to be say 30 years ago. It’s about a 4% extra amount, it invigorates the storms, it provides plenty of moisture for these storms and it’s unfortunate that the public is not associating these with the fact that this is one manifestation of climate change. And the prospects are that these kinds of things will only get bigger and worse in the future."
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  10. Glad to know you're safe and sound John.
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  11. Looking out the window I'm seeing the highest piles of snow in S Finland for my lifetime (under 40 of them) and more coming from the sky. Glad of not to have to go to the store today. Inquiring how are your food supplies? You hang in there.
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  12. Glad you are ok John. Keep smiling.
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  13. Best of luck to you and your family John!



    RE: #2 - the extreme events case has already been pretty well explained. As well as extreme events, there are expected to be regional changes in precipitation. Total global precipitation is expected to go up because of more water vapour in the atmosphere, but some regions will see less & others more. Summary of IPCC graphs here!
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  14. Glad things are not too bad for you, John - here's hoping it stays this way. The scale of this disaster is unimaginable.
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  15. Current status of La Nina:
    http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

    BTW: I was just searching the web for the place where John lives when the new article appeared - all Australians I ever knew came from Sydney so I sort of assumed that he must be from Sydney as well and so was not worried about him - a classical example of wrong generalization
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  16. James Hansen wrote earlier this summer concerning the heat in Moscow and floods in Pakistan:

    "Finally, a comment on frequently asked questions of the sort: Was global warming the
    cause of the 2010 heat wave in Moscow, the 2003 heat wave in Europe, the all-time record high
    temperatures reached in many Asian nations in 2010, the incredible Pakistan flood in 2010? The
    standard scientist answer is "you cannot blame a specific weather/climate event on global
    warming." That answer, to the public, translates as "no".
    However, if the question were posed as "would these events have occurred if atmospheric
    carbon dioxide had remained at its pre-industrial level of 280 ppm?", an appropriate answer in
    that case is "almost certainly not." That answer, to the public, translates as "yes", i.e., humans
    probably bear a responsibility for the extreme event."

    I am sure the same answer would fit the Queensland flood. It would not have happened without AGW. I lived in Acacia Ridge in western Bisbane for three years. I think of my Aussie friends all the time.
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  17. Historic Australian floods: http://www.ga.gov.au/hazards/flood/flood-basics/historic.html are correlated with La Nina http://www.esrl.noaa.gov/psd/enso/climaterisks/years.risk.html plus cyclones.
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  18. Thanks for mentioning cyclones Eric.

    I saw a throwaway comment somewhere that the previous best-known major SE Queensland floods were caused by rain events at the tail end /edge of cyclones. I've not checked it but it did ring a bell.

    Somebody's sure to put those stats together in the next few days.
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  19. I would echo the sentiments that others have so ably expressed about the safety and well-being of not only you and your family, John, but of that of all afflicted by the Queensland floods. May you continue to stay safe and dry!

    The Yooper
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  20. adelady, the throw away comment you read may have been the one @5 above.
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  21. Good to here you're well John.

    No doubt within the AGW scenario harder punches are expected the question really is whether AGW theory is an accurate description of what's going on here. It's also worth considering that nature alone can pack a pretty hard punch. Even in the relatively short history of white settlement in the Brisbane area it's possible that the 1893 was harder although it probably didn't cause so much misery to so many souls.

    garythompson as the response suggests AGW allows for both drought and flood. The problem is that normal precipitation is also not inconsistent with AGW. Once you have all the bases covered it makes me wonder just what is the power of these sorts of statements.

    But this is a terrible tragedy, best of luck to all Queenslanders.
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  22. John,
    As one who lives in a hurricane-prone area, I feel your pain. Keeping up the good work in spite of natural disaster is the mark of a real trooper.

    I heard this morning that Australia's coking coal industry will suffer because of this flooding and that may increase the world steel price. No one can say that the increased risk of disasters of this magnitude won't affect the world's economy.

    Best of luck to you and yours!
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  23. John,

    Good to hear you are managing, but my heart goes out to those stricken by this calamity.

    Here in Mid-Wales we have our first sou-westerly Warm Conveyor of 2011, with orographic enhancement leading to maybe 100mm of rain - but it's steady moderate stuff, not the convective deluges you guys have had.

    With regard to the AGW element of this, one way to look at it is to imagine the weather being the lump sum of money and AGW being the interest - as Kevin Trenberth noted, 4% per extra degree Fahrenheit (or ~6% per degree C if you like).

    Cheers - John
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  24. Albatross

    Even before the present disasters much of this year has been wet in Eastern Australia. It had me looking at the BOM precipitation data a few weeks ago. You can have a look or download the full precipitation data for Eastern Australia here

    This years rainfall has managed to turn the trend for the full record around to a positive trend. I was looking at this because it struck me that even when somebody isn't cherrypicking and even when somebody is using long records it struck me that trend lines had the possibility of being very fickle things.

    Even playing with Hansen's time period if you start it in 1950 the trends negative, start it in 1951 then the trend is positive now that we have data running through to 2010. If you keep Hansen's end date the trend is negative if you start in 1950and it's flat if you start in 1951. I'm not favouring one start/end point or another I'm just trying to highlight the fickleness of some interpretations even when they're based on longish data set trends.

    From memory the IPPC estimate for change in precipitation for East Australia into later this century is between +50% and -50% (which obviously also allows the possibility of 0% change).
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  25. #24 http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch11s11-7-3-2.html
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  26. #21: Regional precipitation projections are very hard, and papers studying them make this clear. The uncertainties are so large that it would be difficult to rule out AGW based on regional precipitation observations.

    However, net increase in atmospheric water vapour is a pretty solid prediction. If you could demonstrate this wasn't happening over a sufficiently long timescale then AGW theory would be in trouble.
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  27. MarR@13 and Mila @25,

    Thanks for linking those IPCC graphs. Fig. 11.17 summarizes things nicely.People are way too quick to make sweeping generalizations "I thought they said AGW was going to cause drought!"? Where, when....?

    The multi-model simulations show the eastern third of Australia typically receiving more rain circa 2100 in DJF, with drying over western third of Australia. If this forecast pans out Perth could be in real trouble. Also not that over the interior the models are showing marked warming but a mixed signal for precipitation-- this suggests an increase in ET and lower soil moisture.

    Perhaps it is best to show the Figure.



    Figure 11.17. Temperature and precipitation changes over Australia and New Zealand from the MMD-A1B simulations. Top row: Annual mean, DJF and JJA temperature change between 1980 to 1999 and 2080 to 2099, averaged over 21 models. Middle row: same as top, but for fractional change in precipitation. Bottom row: number of models out of 21 that project increases in precipitation.

    Source here.
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  28. Regarding ocean temperatures around Australia (from this Australian Bureau of Meteorology report):

    "Based on preliminary data (to November 30), sea surface temperatures in the Australian region during 2010 were +0.54 °C above the 1961 to 1990 average. This is the warmest value on record for the Australian region. Individual high monthly sea surface temperature records were also set during 2010 in March, April, June, September, October and November. Along with favourable hemispheric circulation associated with the 2010 La Niña, very warm sea surface temperatures contributed to the record rainfall and very high humidity across eastern Australia during winter and spring"
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  29. Does this mean that global warming makes both El Nino and La Nina events more likely and stronger?
    Why? I would have thought that anything that makes El Nino more likely, makes La Nina less likely?

    There has already been quite a bit in the comments section stating why extreme events. i.e. both drought and flooding are more likely. Is this statement as robust as say global warming? I would have thought not, particularly as the predictions are regional and regional predictions have larger error margins. Is it possible to quantify how reliable these predictions are? Should Australia start building even bigger dams?

    Perhaps John or another expert could create a more comprehensive post regarding global warming and precipitation?
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  30. The Toowoomba video has gotten wide coverage on US news reports. Seeing the longer version here, I was amazed to hear some of the folks wondering whether they should move their cars. Wasn't it obvious?

    Anyway, as to the attribution issue, the greater amount of moisture is not the only possible AGW impact. There is an hypothesis about AGW-caused pressure altitudes making blocking events stronger and longer-lasting, which could make some weather systems more intense. I don't know if this applies to your flooding season or not, and I've read that many climate scientists are skeptical of this hypothesis. But it is out there as a potential way to make actual cause-and-effect claims for intensification of individual weather events. Some details at http://www.weather.com/blog/weather/8_20427.html. The author is working on a submission to a peer review journal.
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  31. I have said elsewhere, and been criticised for, the idea that intuitively you would expect these extreme weather events to become more extreme and more frequent under global warming. Observation seems to be bearing this out (with each new event met with a chorus by the deniers - ha, you can't say this was caused by global warming, a process which effectively removes all events from being recognised as symptoms). It seems to me that if you have more heat in air and ocean, you have more energy to drive weather events, including the SOI system. If you have more water vapour in one place you get more rain or snow, depending, and you get less moisture in another place. Also seems to me that as we watch the average temperature graph head steadily upwards, we are also seeing the variation around that mean head steadily upwards as well, that is "warm events" are getting warmer, "cold events" are getting warmer. So droughts get exacerbated, so do rain events, depending on the geography of where you are.

    Criticism anyone? Would be good to hear from those who know more about the climatology of this than I do. Perhaps a separate topic John?
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  32. #31: "extreme weather events to become more extreme and more frequent under global warming"

    Don't you just hate it when reality starts showing that you're right?

    See the extreme weather thread for additional examples.

    From Allan and Soden 2008 :
    Climate models suggest that extreme precipitation events will become more common in an anthropogenically warmed climate. ... the observed amplification of rainfall extremes is found to be larger than that predicted by models, implying that projections of future changes in rainfall extremes in response to anthropogenic global warming may be underestimated. -- emphasis added

    And now its personal: Global warming: the impact on global coffee
    --as temperatures rise, coffee will ripen more quickly, leading to a fall in quality.
    --as temperatures rise over the lower lying areas, coffee yields will be adversely affected.
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  33. #31 :
    IPCC AR4:
    http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-8.html

    Update in Copenhagen diagnosis:
    http://www.copenhagendiagnosis.org/
    chapter Extreme events (page 15)
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  34. John:

    Add me to the list of people who are very relieved to hear that you and your family have been spared.

    My wife and I experienced a very bad flood long before we met. We lived on different sides of a river in Pennsylvania that was part of the 1972 Agnes flooding. Ten feet of water on the streets, dikes blew out unleashing a wall of water that knocked dozens of houses off their foundations, a gutted cemetery, and more details I won't begin to inflict on people here.

    So everyone, please spare a donation to the aid organization John mentioned in his post. Being in such a situation is a terrible and unique horror; hopefully a bit of tangible support from strangers can help those struck by this event.
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  35. 31, David Horton,

    My opinion on this is usually that temperatures have not yet risen enough to make any real attributions. One can, in an emotional way, say "ouch, that hurts, what if..." but really there have been killer hurricanes, droughts, floods and more throughout time. I think it's very hard to say "this might not have happened without global warming" at this point in time.

    The day will come, obviously, when the temperature of the planet has risen so much that ecosystems permanently change -- Amazon to savanna, Arctic Ocean to open sea, the U.S. Southwest to expansive desert, Australia to "the warm, wet desert continent" (with flash floods, and so sister to Antarctica, "the cold, wet desert continent"), etc.

    There will also be a day when statistically the number, strength, locations and/or range of hurricanes, tornadoes, monsoons and blizzards has changed enough that there simply is no doubt that we've entered a new paradigm.

    But for now, no, I try to stay away from attributing any single event whatsoever to climate change or current warming.

    And that's one of the dangers of it all -- that the planet will take so long to heat that for the sort of person (i.e. most people) who needs to actually witness the effects to be motivated to take action, it means it will be far, far too late.
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  36. 31, David Horton,

    Just a follow on to my previous post/thought.

    Sad to say, if you think this is bad... "you ain't seen nothing yet."

    Sadly, too, it seems nine people died in the flooding, and 59 are missing. While with my current logic it is too soon to say, I wonder if at some future date those poor souls will be regarded as the first known victims of climate change.
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  37. Sphaerica - "the planet will take so long to heat that for the sort of person (i.e. most people) who needs to actually witness the effects to be motivated to take action" - Yep, frogs in a slowly warming pot of water, heating too slowly to let them know they're actually dinner.

    John Cook - glad to hear you're doing OK. My immense sympathies for those caught in the floods. The '77 Johnstown PA flood happened very close to where I grew up, and I understand what a horrible situation it is.
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  38. Formidable power of water evident in those videos - best of luck to everyone over there being affected.
    Here in the UK, we seem to be currently affected by significant downpours of rain, following on from the downpours of snow a few weeks ago, and there are a few potential problems being forecast in some areas. Nothing like what is occurring in the Southern Hemisphere but more evidence of the amount of water in the atmosphere all over the world.
    Also, the way the temperatures have been here since the cold spell last month, I wouldn't be surprised if this Winter is a lot warmer than the last few weeks of last Autumn. It's odd how the temperatures here have risen as we head towards the middle of Winter. Who knows what will happen next ?
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  39. Martin, the predictions are that Global Warming will make El Nino's and La Nina's stronger, and El Nino's more frequent; which is quite diferent from the way you say it.
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  40. Certainly an interesting topic. Running some numbers on the Clausius-Clapeyron relation a warming of about 0.5 degrees should result in about 5% extra water vapour in the atmosphere. I don't think that would make much difference to the overall flood level. On that basis AGW has very little responsibility for this event.

    But other factors may have contributed. If AGW is changing the ENSO cycle, or some other aspect of our circulation, then it may have made a more significant contribution to this event.

    Of the flood events I can think of for SEQ, many have not been associated with cyclones, but with east coast lows instead. However there was no low associated with this event which does make it at least very unusual.

    And rainfall trends for Australia are uncertain. Modelling I have looked at by CSIRO suggests more rain in the north during summer, and less rain in the south during winter. This matches the basic global expectation that the Hadley Cell should intensify stretching the subtropical dry belt further south, and intensifying the monsoon.

    Long range trends for the last 100 years seem to match this, but if you look at the trend the effect is a lot more subtle than the recent severe droughts which have mostly ended would suggest. Also in the models the south/winter drying trend seems to dominate the north/summer rainier trend, whereas the last 100 years it is more the opposite.

    This spring and summer's weather in Australia also would appear to have a lot to do with the polar vortex, which over the last few decades has shrunk towards Antarctica. Since Spring though it has shown a persistent extension towards Australia introducing colder air, and I believe strengthening the tendancy towards upper level troughing, which has been the dominant factor in recent rains, and not so much the monsoonal/cyclonic type rains that are the primary influence of a La Nina pattern.
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  41. #24 Mila

    It was Table 11.4 for WGII that I was struggling to remember.

    26 MarkR

    It strikes me that "net increase in atmospheric water vapour" is a prediction of a warmer world not specifically AGW. Many AGW critics don't deny we've seen a recent warming trend. It seems to be the attribution of that warming world that's crucial.

    31 David Horton

    I personnally haven't seen a chorus of deniers on this subject but then I haven't seen a chorus of people saying it's AGW. David Karoly at Melbourne (Monash?) University is the only person to make the direct link between these floods and AGW on ABC News24 yesterday.

    There's an image below of the effects of La Nina. I guess if you wanted to make comparisons of modern and older La Nina precipitation you'd have to look at rainfall over the whole region under that green boomerang.



    Within any particular small region under that boomerang (such as Queensland) it's going to be a combination of La Nina and local weather conditions which govern just exactly where the rain is falling. For example some of the earliest flooding events in Queensland in December occured when Tropical Cyclone Tasha dragged in a heap of La Nina rain and flooded three river systems. I'm not sure what's causing the recent flooding of the Brisbane River basin. I'm curious about what happened in respect to the Wivenhoe Dam it seems to have reached peak capacity just at the wrong time but somebody with more knowledge on that would be appreciated.


    More generally there's a couple of links I came across and thought were interesting. The first is a news report, what impressed me was the date it was filed on. The second is a list of Australian climate disasters from the BOM website, it looks like mother nature has been punching hard for a while.

    News report
    BOM climate disasters
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  42. So glad to know you and your family are on high ground, John. What a tragedy. I remember the epic Mississippi River flood of 1993 -- houses and small towns floated away in southern Illinois, where I am from. But that flood seemed to be more a gradual thing. Hang in there.
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  43. Michael @40,

    Good points. Regarding the 5% increase, that was Trenberth's estimated increase for the entire global ocean. So, locally/regionally, values could be much higher-- and that may well have been the case for this event, especially given the record high SSTs surrounding Oz of late. The research papers that will no doubt be published on this in the coming months and years will help shed some more light on the situation.

    As I and others have said, it would not be correct to blame this event entirely or even primarily on AGW-- La Nina almost certainly had a role. But it is, IMHO, likely that the higher SSTs and attendant higher PWV contents made the situation worse.
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  44. In regard to the strength of La Nina, there is a article by Prof Nicholls (link below) that postulates that this is likely to end up being the strongest or second strongest La Nina ever recorded so far. The article does not attribute the strength of La Nina to climate change.
    http://www.abc.net.au/unleashed/42858.html

    I should probably be more careful myself in choosing words and not confuse strong with wet :) We know AGW results in more actual water in the atmosphere. It would be useful to read an article on how the strength of La Nina and El Nino might change with AGW, or if it will. Or if it's more about strong ENSO events having an even greater impact (wet or dry) as we heat up the earth.
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  45. John, so glad to hear that you and the family are OK.

    I live in Melbourne, but all of us are thinking of Queensland.

    Mike @ WtD
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  46. 44 sout

    There's the possibility for the impacts of ENSO to be modulated by natural processes. One interesting relationship is between PDO and ENSO.

    Here's the first paper I've mangaged to have a look at. While it concentrates on East Asia the introduction suggests other researcher have made similar observations in areas affected by ENSO, including Australia. This paper makes the observation that the impact of La Nina or El Nino may be affected by which phase PDO is in. The interesting fact is that we may have recently entered a new negative phase of PDO in the past few years.
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  47. HR:

    "It strikes me that "net increase in atmospheric water vapour" is a prediction of a warmer world not specifically AGW."

    So HR now - and forever in the future one hopes - accepts that the water vapor feedback is real and positive?

    Cool.

    "Many AGW critics don't deny we've seen a recent warming trend."

    Many, however, do.

    "It seems to be the attribution of that warming world that's crucial."

    Unless you deny the basic physics of how CO2 traps long-wave infrared radiation, there's no way to do so.

    If you accept that ... and since you now quite clearly accept the fact that the water vapor feedback is positive and real ... you're already right in the 2.0-4.5C sensitivity to CO2 doubling range cited by the IPCC in AR4.
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  48. Original Post

    It seems that a hot spot of climate science interest is located here in Queensland (John Cook et al..)

    Having been occupied in successfully sandbagging my business in the last 48 hours to see the flood peak pass at the Port Office at 4.5m at 4.00am this morning, I was prompted to look for the 1974 flood (pre-Wivenhoe dam) information;

    The official BOM report is here:

    http://www.bom.gov.au/hydro/flood/qld/fld_reports/brisbane_jan1974.pdf

    A relevant quotation:

    "Meteorological studies suggest that rainfalls well in excess of those recorded in the floods of 1893 and 1974 are possible. Therefore it seems certain that unless
    major flood mitigation schemes, such as the proposed Wivenhoe Dam, are implemented, floods even greater than those of 1974 will again be experienced in
    Brisbane."

    1974 flood peak was 6.6m and in 1893 there were two floods at 9.51 and 9.24m.

    Now there are changes to the hydrology of the river since those dates - but the magnitude of those events (particularly 1893) still far exceeds those of the current event in Brisbane.

    As you all know, AGW officially started around 1975-80, so the 1974 and 1893 events (and those back to 1841) were free of CO2GHG induced extreme event effects.

    I guess the history lesson here is that big floods in Brisbane (and elsewhere in Queensland) might just be 'natural variation' in the climate system.

    If this applies to Brisbane and Queensland - one fails to see why this conclusion would not apply generally.
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  49. KL,

    First and foremost-- sorry yo hear about the flooding Ken, good to read that you managed to keep the waters at bay.

    "As you all know, AGW officially started around 1975-80, so the 1974 and 1893 events (and those back to 1841) were free of CO2GHG induced extreme event effects."

    This argument is akin to saying, "well it has been as warm or warmer in the past, so...."

    The hydrological cycle is accelerating, and extremes in precipitation such as the flooding in Queensland are consistent with that. Also, this event should be considered in the context of the multiple extreme flooding events across the globe in recent years. And as John has pointed out, observations have shown that (globally) extreme precipitation events are already on the rise, and this is still relatively early on in the AGW/ACC story. Also, the increase in weather-related disasters flooding is reflected in Munich Re insurance numbers. But I'm sure that some conspiracy theorists would argue that Munich Re too are part of this alleged grand global conspiracy.

    Interestingly for some time now I have been telling people that those in denial about AGW will still be making excuses to convince themselves that there it is a non issue, even when they are standing knee-deep in water (in that case I'm referring to sea-level rise). I say that in jest, but perhaps it is more accurate than I intended.....

    "I guess the history lesson here is that big floods in Brisbane (and elsewhere in Queensland) might just be 'natural variation' in the climate system.

    Indeed, but nowadays (and especially in the future) with a generous shot/boost of latent energy thanks to higher SSTs and higher PWV contents.
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  50. Ken Lambert, the figures you cite for the earlier floods are from the port office, while the figure for the 2011 flood is from the City Guage. At the City Guage, 1974 peaked at 5.05 meters, while 1841 and 1893 peaked at a little over 8 meters. Given that the Somerset Dam held back a volume of water equivalent to Sydney Harbour in 1974, and that Wivenhoe and Somerset between them held back a volume of water equivalent to 2.65 times the volume of Sydney Harbour; it is apparent that 1974 would have been comparable to 1893 without Somerset, and 2011 would have exceded 1974 without Wivenhoe. It may well have exceded 1893 without both Wivenhoe and Somerset.

    Further, the events in Brisbane are not the most unusual aspect of these floods. Rather, the unprecedented flooding in Toowoomba (with no even partially equivalent experience since 1850) and the Lockyer Valley are far more unusual. So also are the multiple new (absolute) records set for river heights in the Darling Downs, not to mention the repeated flooding with Dalby coping five floods in three weeks.

    Further, the extent of Queensland flooded has set a new record, smashing the previous record which was set in March of 2010.

    Just looking at Brisbane, and ignoring the effect of the dams (and the extensive artificial dranage system) when you do that is extraordinarilly myopic.

    This does not prove it is not simply natural variation. But if it is, it sets a new measured extreme for natural variation. And it just happens to coincide with the warmest sea surface temperatues in Australian waters on record. Further, pretending that there is not overwelhming evidence for anthropogenic global warming as the back drop to this event involves even more myopia than your survey of Queensland floods.
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