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Are the NSW bushfires linked to climate change?

The New South Wales fires have sparked a hot debate on the question whether these fires are linked to climate change. Prime Minister Tony Abbott joined in too stating, “These fires are certainly not a…

The Prime Minister knows a lot about fires, but does he understand their connection with climate change? AAP Image/Dan Himbrechts

The New South Wales fires have sparked a hot debate on the question whether these fires are linked to climate change. Prime Minister Tony Abbott joined in too stating, “These fires are certainly not a function of climate change - they’re just a function of life in Australia”.

With first-hand experience in fire fighting, the PM can talk with some authority about bushfires. But does the science support the PM’s assertion about the fires and climate change or his high confidence in that assessment?

The present fire activity in eastern NSW is extreme and consistent with what we know about climate-fire relations and the below-average rainfall and above-average temperatures of the last six months. However, whether the current fires in NSW are related to climate change is unknown.

This relationship will remain uncertain until we know to what extent the anomalous climate conditions of 2013 in Australia are within the natural variability of the region or an expression of global environmental changes.

The last report of the Intergovernmental Panel on Climate Change (IPCC) repeatedly states that anomalous seasonal conditions and changes in the frequency and intensity of extreme weather events are likely in future. But it emphasises that prediction of future conditions are inherently uncertain, while making no specific predictions about Australian bushfires in particular.

Consistent with that uncertainty, the IPCC uses a well-defined scale to express the likelihood of their science-based assessments. The IPCC likelihood scale goes from “exceptionally unlikely” for probabilities of 0-1% to “virtually certain” for probabilities of 99-100%.

The term “certainly” is not included in their terminology. By suggesting certainty where it doesn’t exist, the PM appears disconnected from the relevant science.

So what’s the science behind the PM’s second assertion, about fires being just part of life in Australia? Though basically true, some nuance is needed for a productive discussion. Fire is an integral aspect of most Australian environments, but there are important variations in the frequency, season, sizes, intensity and impacts of burning.

Basic biophysical principles cause these fire properties to be related, such that certain combinations (such as frequent, low-intensity fire in winter or infrequent, high-intensity fire in summer) occur over large areas while others are rare (such as frequent, high-intensity fire). In fire research and management those combinations of fire properties are often referred to as “fire regimes”.

Though regional differences in Australian fire regimes have been known for many decades, a continental classification and mapping was published only recently. How continental and global fire regimes are related to climate remains incompletely understood and poorly quantified, with associated uncertainty about potential changes under projected future climates.

We know that bushfires can only occur where and when the following four limiting factors are overcome:

  1. There must be at least some ground cover of plant material or fuel.

  2. Fuel must be dry enough to burn.

  3. There must be an ignition.

  4. Weather conditions must be favourable for the fire to propagate across the landscape.

The four limiting factors are like switches in an electrical circuit: a fire requires all four switches to be “on”. Across Australia there is important variation in the frequency with which the four switches are “on” or “off” producing a rich pattern of fire regimes.

In many of our arid environments fuel material is scarce and patchy for much of the time but can be abundant enough after above-average rainfall to support large fires. On the other hand, in our more humid climates of the southeast, forests and woodlands produce large quantities of fuel material but that fuel will be too wet to burn for much of the time. It is very difficult to assess exactly when and where forest fuels are dry enough to burn.

We do know that large forest fires like the present ones in the Blue Mountains tend to occur when dry fuel areas become widespread and spatially connected.

The four-switch model provides useful guidance for evaluating effects of climate change on fire. It captures the key mechanisms underlying the diversity of fire regimes and, importantly, clarifies that fire results from processes operating at disparate time scales.

The distribution and species composition of forests and woodlands in Australia reflects long-term climate conditions and related fire regimes. This may change in response to altered future climate and elevated atmospheric CO2. But such changes will be relatively slow (probably over decades), though potentially reinforced by altered fire regimes.

At seasonal or annual time scales, the critical switch for fire occurrence in forests in the southeast is related to fuel dryness. Hence, changes in the frequency, intensity, timing or duration of dry weather conditions can potentially affect fire activity in this environment. Once the fuel dryness switch is flicked “on”, fire activity becomes a function of the occurrence of ignition sources and hot windy weather conditions.

In conclusion, we can be virtually certain that fire activity in Australia will respond if climate change were to affect one or more of the mentioned switches. We can also be virtually certain that altered fire regimes will have potentially far-reaching implications for life in Australia.

One of the few certainties here is that we need to invest in a strong science base to guide us forward in case the future turns out different from what it used to be.

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    1. Craig Read

      logged in via Twitter

      In reply to Mike Hansen

      Some might malign Wikipedia, but it does show up some interesting trends.

      https://en.wikipedia.org/wiki/Bushfires_in_Australia

      According to the above page, our major bush fires have been:

      6 Feb 1851 (Vic)

      1 Feb 1898 (Vic)

      Feb - Mar 1926 (Vic)

      Dec 1938 - Jan 1939 (vic)

      14 Jan - 14 Feb 1944 (Vic)

      Summer 1951-1952 (Vic)
      2 Jan 1955 (SA)

      Jan-Mar 1961 (WA)
      14-16 Jan 1962 (Vic)
      5-14 Mar 1965 (NSW)
      7 Feb 1967 (Tas)
      19 Feb 1968 (Vic)
      8 Jan 1969 (Vic)

      12 Feb 1977 (Vic…

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    2. Craig Read

      logged in via Twitter

      In reply to Mike Hansen

      I did try to group those dates by decade, but it appears the auto-reformatting gremlins have undone it.

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    3. Felix MacNeill

      Environmental Manager

      In reply to Mike Hansen

      Thanks Craig - as you say, not exactly a rigorous scientific analysis, but it does show a pretty interesting decade-to-decade distribution pattern!

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    4. Geoff Henley

      Research Associate in Health Statistics at Flinders University

      In reply to Mike Hansen

      Wikipedia is OK for certain facts, dates etc. but as a source information regarding the scientific basis for factors associated with climate change it has been exposed as biased and unreliable.

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    5. In reply to Mike Hansen

      Comment removed by moderator.

    6. Felix MacNeill

      Environmental Manager

      In reply to Mike Hansen

      Just as well Craig was only using it to findf a simple list of uncontroversial dates then, wasn't it?

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    7. In reply to Mike Hansen

      Comment removed by moderator.

    8. Des Stackpole

      Post hole Digger

      In reply to Mike Hansen

      No fires recorded outside Victoria between 1850 and 1950?
      Only 2 big fires in the 18th century?
      I'm not blaming Wiki as they are just listing what's easily available.
      It's up to the user to evaluate and interpret appropriately.

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    9. Peter Ormonde
      Peter Ormonde is a Friend of The Conversation.

      Farmer

      In reply to Mike Hansen

      All depends what we mean by "big" ... don't forget most fires in our history have been fought with hessian bags, fire flappers and rakes - no water, no pumps. They basically burned themselves out. So acreage "devastated" doesn't necessarily mean "big" in the sense we are now talking. When we are talking big we mean fast and extremely hot.

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    10. Des Stackpole

      Post hole Digger

      In reply to Mike Hansen

      There were less people out there then, so fires may have been as big or bigger, but hardly anyone noticed, and those who did were to busy on a wet sack to have time to pen a report to the regional newspaper.

      Today there is have better recording, so there's more (i) incidents recorded, and (ii) likelihood of one or several of them will hit a record high area/human death/temperature/FDI/n koalas burnt.

      Both statistics are liable to either misinterpretation or misrepresentation.

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    11. Peter Ormonde
      Peter Ormonde is a Friend of The Conversation.

      Farmer

      In reply to Mike Hansen

      Yep that's the whole point Des ... some of these fires in the 1800s and early party of the 1900s were massive grass fires - killed a lot of sheep in particular and burnt out thousands of square miles - largely because what effort could be mustered went into protecting houses and outbuildings. Quite a few came about from the practice of burning the stubble in wheat fields.

      The locals around here only recently gave up burning their pastures - since the 1970s or so. Quite unusual for dairy and cattle farmers to be burning their paddocks actually and there's a reasonable line of thought suggesting they adopted the practice from the local Aboriginal folks who burned the grasslands very often indeed to excellent effect.

      The point is that we're dealing with a rather new phenomenon with these extremely high temperature fires and the way they behave - and also when they happen. Thank god we've got better at it since the days of flapping about with a bit of wet hessian!

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    12. In reply to Mike Hansen

      Comment removed by moderator.

    13. John Phillip
      John Phillip is a Friend of The Conversation.

      Grumpy Old Man

      In reply to Mike Hansen

      Did you catch Steffen's interview with Tim Lester (http://www.watoday.com.au/environment/climate-debate-must-stick-to-the-science-professor-20131025-2w76n.html), Geoff. It makes for amusing viewing. The regular confusion of where emissions are going globally and what we can do about it here in this country seems to be a cornerstone of those on the more alarmist side of the argument. They are beyond reluctant to quantify the effect that Australian action will have on global temps. This is particularly noteworthy given the way that certain commentators - Milne, Bandt, Marr for example - are ready to claim that Abbott's policy is going to lead to higher temps.

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    14. John Phillip
      John Phillip is a Friend of The Conversation.

      Grumpy Old Man

      In reply to Mike Hansen

      ALso: Love the part where Steffen states that Australia is one of the major emitters - at LESS than 1.5% this statement is beyond laughable. (He said it with a straight face too.) They cant claim that there is a global carbon budget - an absolute- and then make this sort of assertion.

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    15. Mike Hansen

      Mr.

      In reply to Mike Hansen

      @John Phillip responding to my criticism of Henley who described Professor Steffen and Professor Hughes as "alarmist clowns"!

      "Putting bullshit words into someone else's mouth again Michael. Is it because you are too much of a zealot to actually discuss the points or are you just too damn thick? Keep up the stupidity you ignorant troll."

      Could other posters here not report this comment. John has set himself up as the "ad hom" policeman despite being a hyprocrite, so it will be useful to keep as a reminder to him.

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    16. Sean Arundell

      Uncommon Common Sense

      In reply to Mike Hansen

      @Craig re " it would be interesting to see the gaps mapped against ENSO." Sure would be. This seems to rely upon Govt et al funding such efforts for the good of. The Canberra fires and Vic disaster are two special cases, imho, were the ferocity was unmatched in living & recorded memory. The behaviour of such recent fires is more critical than the numbers or timing imho, and must be adequately evaluated. The list is a good one, despite any gaps. Wiki is a useful tool and starting point, if people…

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    17. Felix MacNeill

      Environmental Manager

      In reply to Mike Hansen

      John, robust debate is part of the scene here, but that is just empty abuse.

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    18. Sean Arundell

      Uncommon Common Sense

      In reply to Mike Hansen

      PS A while back I did some checking, and found that the 2009 Vic fires (whilst far worse) was in many regards a repeat of the 1925/26 Vic fire disaster. http://en.wikipedia.org/wiki/1925%E2%80%9326_Victorian_bushfire_season . If you dig a bit deeper into Kinglake specifically, one will notice that entire township and surrounds was completely destroyed on both occasions causing much loss of life. Post 1926 the town was rebuilt. Post 2009 the town has been rebuilt. One could well ask on what rational…

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    19. Sean Arundell

      Uncommon Common Sense

      In reply to Mike Hansen

      Des, good point re gaps in wiki knowledge/data. My feelings are is that it is not ONLY up to the user. Nothing is stopping anyone in the Public Service, Govt Ministries, CSIRO, RFS, Emerg. mngt. etc people from adding their own REFS to pages like this. It would take less than 3 minutes to type a one sentence entry, and insert the source ref with url to the latest most up-to-date dot.gov resource. eg Marc's find http://www.emknowledge.gov.au/disaster-information/ And while they are there, delete what is erroneous. Too easy Campese and yet impossible! :(

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    20. John Phillip
      John Phillip is a Friend of The Conversation.

      Grumpy Old Man

      In reply to Mike Hansen

      I agree with you Felix. I am just giving Mike a bit of his own back as he is forever putting words into the mouths of those he either doesnt agree with or doesnt understand. If it's not that, he simply verbals them. I am fully expecting the comment to be edited out. What would be appropriate would be for him to attack their arguments/comments with substantiated facts and data. Something he has, to date, steadfastly refused to do.

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    1. Mike Hansen

      Mr.

      In reply to Suzy Gneist

      "many can't see the wood for the trees". Not all.

      "THE Prime Minister, John Howard, last night embraced a key climate change forecast, warning Australians to prepare for more extreme weather events such as the current bushfires.
      Visiting north-east Tasmania, he repeatedly made the point that the region was not normally associated with bushfires, and neither were they usually so common early in the summer.
      On his last stop in St Helens, Mr Howard was asked if he accepted the scientists' predictions of more extreme weather events.
      "Let me put it this way," he said. "I think the country should prepare for a continuation of what we are now experiencing … I think the likelihood of this going on is very strong."

      http://www.smh.com.au/news/scorchedearth/pm-expect-extreme-weather/2006/12/13/1165685752372.html

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  1. Dick Adams

    logged in via email @hotmail.com

    Climate Scientists tell us that climate change is a reality. They are the best equipped to provide advice in this respect – This is broadly accepted.

    Australian fire scientists tell us the impact of climate change on fire behaviour, management and ecology – This too is broadly accepted, it is negligible.

    Google Dr Phil Cheney – former head of the CSIRO’s fire research unit.
    If people espouse the importance of listening to the science – then do it.

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    1. Mike Hansen

      Mr.

      In reply to Dick Adams

      Here is an paper from members of the CSIRO's fire research unit.

      "A data set of observed fire weather in Australia from 1973–2010 is analysed for trends using the McArthur Forest Fire Danger Index (FFDI). Annual cumulative FFDI, which integrates daily fire weather across the year, increased significantly at 16 of 38 stations. Annual 90th percentile FFDI increased significantly at 24 stations over the same period. None of the stations examined recorded a significant decrease in FFDI."

      http://onlinelibrary.wiley.com/doi/10.1002/joc.3480/abstract

      It was discussed in this article in the Fairfax press.

      Read more: http://www.smh.com.au/environment/climate-change/tony-abbott-should-never-say-never-about-climate-change-bushfire-link-20131025-2w5pt.html#ixzz2ih6cpyqP

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    2. Dick Adams

      logged in via email @hotmail.com

      In reply to Dick Adams

      You forgot the last paragraph

      “Although these trends are consistent with projected impacts of climate change on FFDI, this study cannot separate the influence of climate change, if any, with that of natural variability” - Copyright © 2012 Royal Meteorological Society (Climate Scientists – not fire scientists)

      I any case, you miss my point and that of the leading scientific minds on Australian fire behavior.

      No one is disputing that climate change will lengthen the fire season or create a high frequency of high FDR’s in a country that has always been over-represented in this area.

      However, In a country where conditions are ripe for mega fires on 40 days (for arguments sake) per annum, increasing it to (on average) 45 is neither here nor there.

      Meet the elephant in the room – FUEL!.

      Google Dr. Phil Cheney’s interview on ABC Classic FM the other day. It is very interesting.

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    3. Mike Hansen

      Mr.

      In reply to Dick Adams

      You are right. I misread Hannan's article about them being CSIRO fire researchers although they do publish in the "International Journal of Wildland Fire"
      http://www.publish.csiro.au/?paper=WF10070

      I would take issue with your point "However, In a country where conditions are ripe for mega fires on 40 days (for arguments sake) per annum, increasing it to (on average) 45 is neither here nor there."

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    4. Mike Swinbourne

      logged in via Facebook

      In reply to Dick Adams

      Sorry Dick

      '....No one is disputing that climate change will lengthen the fire season or create a high frequency of high FDR’s in a country that has always been over-represented in this area...."

      Yeah they are - lots of them. Including such luminaries as our PM and Environment Minister.

      "....However, In a country where conditions are ripe for mega fires on 40 days (for arguments sake) per annum, increasing it to (on average) 45 is neither here nor there...."

      Leaving aside the issue of your numbers (I know you are only using them as an example), are you really saying that a 17% increase in the risk of 'mega fires' is nothing to worry about? Gee - I can't help but disagree with you.

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    5. Dick Adams

      logged in via email @hotmail.com

      In reply to Dick Adams

      Ignore my numbers, there was no scientific reasoning behind them, I was just trying to make a point – which keeps getting missed.

      My point is, these are not MY views, however, they reflect over 80 years of scientific inquiry into a specialised field, by the likes of Alan MacArthur and Phil Cheney, which is directly related to this discussion.

      Feel free to take exception to scientifically proven facts. But how do you differ from climate sceptics if you choose to ignore the science when it doesn’t align with what you want to think.

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    6. Mike Swinbourne

      logged in via Facebook

      In reply to Dick Adams

      Sorry Dick, could you please point to the 'scientifically proven facts' that I am supposedly ignoring.

      Firstly - and this is something you need to understand about science - it does not deal with proof. That is a mathematical construct. Science deals with probabilities. But let's leave that aside for the more important aspects of your argument.

      You quoted from - your words - the last paragraph of a study that you are relying upon to support your position. However, it isn't the last paragraph…

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    7. Jane Rawson

      Editor, Energy & Environment at The Conversation

      In reply to Dick Adams

      Dr Boer is an Australian fire scientist.

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    8. John Vacey

      Sciolist

      In reply to Dick Adams

      Hi Dick. Couldn't find Phil Cheney's recent ABC FM piece, but I'm respect his experience and am well aware of his findings re fuel loads as the only controllable factor in pre-emptive fire management. I'm actually hoping Phil is following this thread and can respond. I wasn't in Canberra during the 2003 fires (not that my presence would have helped...) but I did travel along the 5 km or so of the Cotter Road a week or so later. On one north side was Mt Stromlo with all the fire planning nightmares…

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    9. Dave McRae

      logged in via Twitter

      In reply to Dick Adams

      Yes John, me too.

      How did those fires travel across the equestrian paddocks to smash into Chapman and Kambah. Those paddocks was mostly dust and some faecal matter. I say half-jokingly, was it the horse poo? And I know there were several people burnt badly, some permanently disfigured bravely trying to save horses. So it's wrong to make light, yet it is so frustrating, what was the fuel?

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  2. Mark Poynter

    Forester

    The question that should be being examined is not whether there is some link to climate change; but whether any link is a significant driver of what we are currently seeing compared to other pre-existing factors such as changes to land management, fire-fightimg methodology, and societal changes such as where people are now living.

    It is notable that nearly all the support for climate change as the driver of a new era of hotter bushfires is being made by those who have no practical background…

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    1. Felix MacNeill

      Environmental Manager

      In reply to Mark Poynter

      Mark, I don't think anyone is denying the points you make and I'm not sure there are many people claiming that climate change is 'wholly responsible for greater bushfire severity' - all I've ever understood Adam Bandt and others as having endeavoured to point out was that fires are only going to get worse under climate change.

      Though, allowing for the ENSO patterns of the last few years, the fact that we've just been through an exceptionally hot summer and September is very likely to have had…

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  3. Fred Moore

    Builder

    Bushfires are part of very narrow natural global energy circuits. Humans live at the chokepoints of these circuits (eg Blue mnts corridor and Sydney Basin) for one reason. To collect that energy as energy EQUALS life.

    CO2 levels and warming play maybe 5% of a part in the calamities that occur along such circuits.

    These circuits are analogous to an electric current. You have Positive terminals In the dead Heart and up in the Coral and Timor seas. You have cool negative terminals in the…

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  4. Roger Jones

    Professorial Research Fellow at Victoria University

    "This relationship will remain uncertain until we know to what extent the anomalous climate conditions of 2013 in Australia are within the natural variability of the region or an expression of global environmental changes."

    With all respect, Matthias, we know this. It's because both national and regional temperatures have been attributed previously and it's not done to say some seasons and years are affected, and some years are not.

    Karoly, D.J. and K. Braganza, 2005: A new approach to detection…

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  5. Geoff Henley

    Research Associate in Health Statistics at Flinders University

    "But it emphasises that prediction of future conditions are inherently uncertain, while making no specific predictions about Australian bushfires in particular."

    So in other words, the IPCC report provides no explicit evidence of a link between climate change (human-induced?) and the NSW bushfires. Better not tell the ABC or Fairfax that. Wouldn't want the facts to get in the way of a good story.

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    1. Mike Hansen

      Mr.

      In reply to Geoff Henley

      What the IPCC AR5 SPM says.

      "Changes in many extreme weather and climate events have been observed since about 1950 (see Table SPM.1 for details). It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale6. It is
      likely that the frequency of heat waves has increased in large parts of Europe, Asia and Australia."

      * very likely 90–100%, likely 66–100%,
      http://www.climatechange2013.org/images/uploads/WGIAR5-SPM_Approved27Sep2013.pdf

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  6. Marc Hendrickx

    Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

    There is no doubt that Climate change will affect bushfires in some way. Increases in temperature whether mild as proposed by lukewarmers or extreme as advocated by alarmists will certainly affect the bushfire equation. This includes other factors including fuel load, fuel moisture, humidity etc. All these variables are also subject to influence by climate. In this context it would be fair to say that to some extent the current fires have been influenced by the mild climate change we have had since…

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  7. Ian Alexander

    Reader

    Are the NSW bushfires linked to climate change?

    Yes

    Is our new PM acting like a coal industry stooge?

    Yes

    Is Wikipedia Australia's new Department of Science?

    Sure looks like it.

    What does the LNP think about Climate Change?

    Whatever Gina tells them to.

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  8. Garry Baker

    researcher

    So - Prime Minister Tony Abbott joined in too stating, “These fires are certainly not a function of climate change - they’re just a function of life in Australia”.

    Well maybe the latter part of his comment has historical truths to support it - However one might reasonably ask where are his proofs for the front half of the comment. Indeed, lets hear them

    Mr Abbott may not be aware of it, but he's been a candidate for going on a Village Idiots list since he declared climate change was a lot of rubbish, and the more he opens his mouth on things to do with climate, the more he reinforces a public view that he deserves the award.

    ie: There he goes - a man who carries a great weight of ignorance on his shoulders about important things - Why on earth do we have him as PM

    Whereas his PM in waiting, well at least he had the nous to pause for a bit, then pick up on the public concern. May not be a believer, but he at least sounds like one.

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  9. john davies
    john davies is a Friend of The Conversation.

    retired engineer

    This question is a "no brainier."
    It is indisputable that the effects of climate change are increasing the risks and intensity of bushfires in this country. Too many of the experts, including those with enormous experience in fighting fires and studying the subject, agree on the matter to believe otherwise. Those who do believe otherwise are either dumb, misinformed or blinded by political ideology (on what should never have become a political issue).
    The last thing TA wants is the "productive discussion" referred to in this article. That would be too embarrassing, and remind more people of how he got to where he is in the first place. The man is a charlatan, and Greg Hunt seems intent on convincing the world he is an idiot (which I do not believe he is).

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    1. Ian Bryant

      logged in via email @tpg.com.au

      In reply to john davies

      No, Hunt it just behaving like an idiot. There is a difference, and it's very dangerous. We have much more to fear when Intelligent people behave like idiots than when idiots do.

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  10. Ian Bryant

    logged in via email @tpg.com.au

    OK so Abbott is convinced there is no direct correlation between AGW and the bushfires. Can I put it to those who support this view: just what evidence would cause you to change your minds? Exactly what sort of evidence would compel you to accept that AGW was responsible for increased bush fires?

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  11. Ben Marshall
    Ben Marshall is a Friend of The Conversation.

    Writer

    Good article full of talking points, thank you.

    Re. use in final paras of 'virtually certain', with respect, I think you mean 'reasonably certain'.

    Re. climate conditions in the future responding to climate change, I would argue that the use of the word 'future' is inappropriate and unrealistic in the present context. Climate is changing now, and has been changing over the last century. This has effects on weather, and therefore on fire risk, intensity and level of damage.

    Re. changes…

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  12. Peter Wilkin

    Australian Realist

    Over three hundred thousand people died of aids in South Africa because Thabo Mbeki decided he knew better than the scientists, and that Aids was caused by poverty not HIV.

    I suppose Tony Abbot can rest assured that it will be much more difficult to put an actual figure to the death toll that will come of delaying Australia's response to greenhouse gas induced climate change by his irresponsibly overturning the carbon tax.

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