Climate Change Sceptics

Denial vs Good Science Part I

Earlier this year I was asked to write a ConScience opinion piece for Australasian Science magazine (one of the two popular science mags in Oz, along with COSMOS). It was entitled “Make a stand for good science”. Here is the first part:

“Don’t feed the troll!” This is a common admonition in the expanding science blogosphere – at least the rational quarters. Trolls, in the Internet vernacular, are people who intentionally post false or controversial messages to gain attention or foment a conflicting style of debate. Most remain shielded within the anonymous confines of their online pseudonym. A rare but vocal few are sufficiently emboldened by self-confidence (or hubris) to speak out in public.

For the long-standing “debate” over the relative merits of evolution versus creationism, they usually style themselves as “creation scientists” or “intelligent designists”. In climate science and policy, those few apparently well-educated people who continue to deny the now vast body of scientific knowledge and analysis on the causes and consequences of global warming are variously called sceptics, denialists, contrarians, delayers or delusionists [Ed: I now simply call them ‘non-greenhouse theorists’ because that, ultimately, must be their position]. Whatever the label you attach to them, they are all cut of the same anti-intellectual cloth.

Their business is the dissemination of disinformation, doubt and unscientific nonsense. One of their most regular ploys is to leverage the widespread lack of public appreciation of how science operates. The scientific process of theoretical postulates, hypothesis testing, critical evaluation (and re-evaluation) of ever accumulating empirical evidence, model validation and peer review is inherently complex and often technical…

For the full article, read on ABC Online here.

It stirred the pot enough to also warrant getting reproduced on Online Opinion and in The Australian newspaper. It was then picked up in various news stories and a few contrarian blogs. It also elicited a barrage of “heated” emails over the next few weeks – more on that phenomenon in another blog post.

But most of the hundreds of commenters who responded to the above postings seemed to have missed the point. Predominantly, they accused me of “trying to shut down the debate”. That was not my intention – my view was simply that the misrepresentations, rife in this arena, needed to be eliminated. I explained this in a follow-up post:

The issue I have with many “sceptics” is not at all that they are sceptical (that is a healthy part of science). It is that they either use their qualifications or position, or cherry-picked information, as the primary or sole justification for refuting evidence. The most notorious choose to take what I have seen colourfully referred to as the “la la la la, we can’t hear you” approach to serious scientific rebuttals. To argue, as a contrarian has recently done, that the atmosphere is simply too large a domain for us to ever understand, is tantamount to anti-intellectualism (though in a quite different vein to the deliberate spreading of disinformation or incomplete explanations), because it flippantly ignores over a century of scientific progress, hard-won accumulation of empirical evidence, and model-based evaluation on this very issue. This includes predictions of warming made decades before it happened (that is, validation), and multiple strands of constantly updated theory and data that point clearly in the direction of global warming and the mechanisms for it. In some senses, the standard contrarian approach strikes me as an attempt to use Platonic inductive logic to trump evidence-based science and scientific hypothesis testing (sensu lato).

In my Opinion Piece printed above, I deliberately didn’t mention consensus or “settled science” because it is certainly not the point. Consensus is simply an emergent property of strong, consistent evidence and lack of credible or verifiable contradictory evidence or theory. It cannot be shattered, but neither is it immobile. It shifts its bulk as the evidence accumulates. I acknowledge that it is slow to change. New ideas, sometimes radical ideas, that are backed up by new evidence are actually the grist of good science, and are readily debated in all fields of scientific endeavour (I would refer you to Fred Pearce’s “With Speed and Violence” book for an excellent overview of many of these, especially with respect to paleo evidence for abrupt climate change due, in all likelihood, to very strong positive feedbacks). Uncertainty about processes, mechanisms and deterministic versus stochastic and chaotic influences are a constant source of debate (that is the debate going on every day in scientific journals and conferences).

As such, I do not consider many ‘sceptical’ scientists who argue over relative values of radiative forcing of solar, clouds, and long lived greenhouses gases, or strengths of feedbacks, as deniers or anti-intellectual. People such as John Christy, Richard Lindzen, Christopher Landsea, Henrik Svensmark, Bjorn Lomborg, etc. unduly (in my view) play down the importance of climate change or the importance of long-lived greenhouse gas forcing and amplifying feedbacks, but at least they publish on climatology or related disciplines and are willing to engage on academic terms, which was exactly my point – this is what they should be doing – subjecting their ideas to rigorous scrutiny and scientific debate. There are many in the field of conservation biology who consider climate change impacts to be a distraction given other pressing threats to biodiversity. Again, I choose to differ strongly in my interpretation of the threats, but that is a matter of scientific interpretation. Not spin.

Put simply, to dismiss over a century of progress with a wave of your hand over your keyboard. “we barely understand ‘climate’. It is too vast a domain”, lacks context. Barely understand relative to what? The world is riddled with complex systems for which we have incomplete understanding, but sufficient grasp of (and evidence for processes) to make informed conjecture about cause and effect – and hence (in this context) predictions of response to climate forcing. I maintain that your stand is but one step away from anti-science, because progress in any field can conveniently be characterised as mostly incomplete and therefore unreliable. Following this logic, you’d best switch off that electronic device you are typing on – after all, we really actually understand so little about the quantum dynamics of the circuit board and the behaviour of those electrons.

Time will tell for global warming in one sense – evidence will continue to accumulate, uncertainties will continue to be examined and debated, CO2 will continue to build. Unexpected things may happen that either amplify or negate the change (models suggest the former is more likely, but models are simply caricatures of our understanding of the real world, and are therefore always limited and simplified). An expectation of absolute proof on the other hand is not science. In only the most trivial issues can there ever be proof. The issue of global risk management of the Earth System will be heightened whilst more and more uncertainties are ironed out, or refuted, or re-formulated.

The concern is that at some point – perhaps soon – positive feedbacks and hysteresis takes the problem forever out of our hands. At that point, there is no chance for re-evaluation of policy or reparations via drastic counter-action. That is what is meant when it is said that we are running out of time. How long are we willing to “risk it” before we take some serious insurance? That is the core argument for current policy, nationally and globally.

More on how this “debate” has continued to evolve in a later post…

Barry W. Brook

By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

31 replies on “Denial vs Good Science Part I”

I think you’re really missing the point, Professor. I include myself in the sceptic camp not because of the science – as the science is pretty straight forward. There is human induced warming and it is a problem. I include myself in the sceptic camp simply because I find the other group’s views repulsive and dangerous.

The science of global warming is actually the easy part. The hard part is to know what to do about it in a way that doesn’t imperil human living standards. The ETS is a case in point. What we ought to be doing is imposing a carbon tax with an income tax set-off tied to a formula that would increase or decrease depending on forward climate change estimates. The ETS on the other hand is a giant big government redistribution scheme that will do little or nothing to mitigate. In fact it could make things worse. Not allowing the nuclear option in the mix is about as dumb an idea as you can have especially when the other technologies are not yet economically efficient.

One related point: it is not that obvious we need to mitigate even if we apply Stern’s science/economic parameters. Here’s why.

Global GDP is currently $50 billion (approx). Stern suggests that we will experience a drop of 20% of GDP potential by 2100 without mitigation.

Current Global GDP US$50 trillion.

Unmolested Global GDP by 2100 assuming 3.5% growth rate is US$1,184 trillion. Assuming Stern’s forecast of a 20% drop global GDP would be US$947 trillion.

Applying Stern’s mitigation recommendation if taking 1% of the GDP growth rate and applying it to mitigation we end up with Global GDP of US$485 .

So it is not obvious that we should mitigate rather than leave GDP to accumulate unmolested over the next 92 odd years. And if we are to mitigate would wouldn’t the cheap way be the way forward such as massive large reforestation?

So the real divide ought to be between the economic denialists and the economic realists and I’m afraid the current crap of mitigation proponents don’t have the winning argument.


I am not a sceptic,nor am I convinced.Science ,as much as there will be a need to be religious in some matters isn’t about beliefs proofs or disproofs.So many times I have read and heard this.If knowledge is understanding,then how many completely indulged atmospheric scientists are available to completely convince us 100 years is enough to be the expert dependable enough,without a bit of senility setting in,by answering the same questions in a similar way,rather than trying to achieve nodal freedom.Building up from far distant points of understanding enough understanding to cover the same groun from another point.[D after n]………………………………..So expertise bothers me,when self-assured becomes a habit.The challenge in not understanding the atmosphere after a hundred years of research isnt, the dishonesty of that statement,if the statement came from the position of a sense of humility,rather than accepting the empirical domain of collected understandings,the challenge is that that it implies a lack of humility in those who will claim that empirical data,will remain unchallengeable.And that seems anti-science to declare that enough scientific evidence is embodied in the Hundred years.I am not a sceptic of the science or its implied as totality understanding.I simply cannot be.But it is sort of trading horseshit,when scepticisms on either side,seems to be dependent on personal matters,and the dunny roll of academic importance.


Really Barry, I suggest go over at the other thread and take a better look…. and then come back here and apologize for making that dishonest claim.

I also suggest you answer my questions otherwise I would have to say that you are “less then genuine” if you claim to be running a site “Getting to grips with the brave new world of future climate”. Go on, answer the questions. That’s a dare as i have already carved up your buddy to shreds.


JC’s really not worth the trouble. If he continues posting here, it will just turn off people who are genuinely interested in learning about climate science but don’t want to put up with rude attacks of the kind JC specializes in.


It’s really off-topic, but, JC, can you clarify your financial argument against mitigation? Your analysis really isn’t very clear. For instance, you’ve included two contradictory values for the current global GDP: “$50 billion” and “US$50 trillion”.

Can you also clarify whether you think Stern recommends spending 1% of global gross GDP or whether he suggests spending 1% of the global GDP growth rate.


“Can you also clarify whether you think Stern recommends spending 1% of global gross GDP or whether he suggests spending 1% of the global GDP growth rate.”

Ummm, yeah, just realised that was a big pile of stupid.


Jc’s first post is typical of the pseudo-logic and incorrect assertion we see all too often.

eg: “The hard part is to know what to do about it in a way that doesn’t imperil human living standards.”

Love that word “imperil”.

No, Jc, whatever we choose to do will have a cost. The hard part is to know what to do about it in a way that has the lowest cost and therefore imperils human living standards the least.

This is why the government isn’t going to tell each industry or household how much greenhouse gas they can emit but will put a cap on total emissions and pretty much leave it to market forces to work it out. Markets are not infallible, but they’re pretty good at that sort of thing.

Doing nothing is clearly not the least-cost option. This is why a “cap and trade” scheme is being proposed by Garnaut. Limit the amount of greenhouse gas emission by law, and let the market sort out the most efficient way of using it.

The implication of your post is that the “do-nothing” option is without cost, which is of course a lot of baloney.

eg again:

“The ETS on the other hand is a giant big government redistribution scheme that will do little or nothing to mitigate.”

More baloney. Read the Garnaut report, Jc. If the government by law caps the amount of greenhouse gases that can be emitted, greenhouse gase emissions will be mitigated. How terribly hard is that to understand?


“If the government by law caps the amount of greenhouse gases that can be emitted, greenhouse gas emissions will be mitigated.”

So Gaz if China, India and the other big emitters don’t cap their emissions what’s the point?

And Barry, if Australia shuts up shop and we reduce our so called ‘carbon pollution’ to zero the planet will cool by how much?

Our incredible planet saving cooling will return the globe to an ‘optimum’ climate by when?

On that point, what is the optimum climate for the planet – the Ordovician, Cambrian, early or late Holocene (you can name your own if you like) and why?


PeterW asks: “So Gaz if China, India and the other big emitters don’t cap their emissions what’s the point?”

Well if they never do, and that’s a very big “if”, all we’ll have done would be to reduce our GDP growth rate and saved some of our coal for later, although over the long run that will be the least of our worries as the temperature continues to rise.

I think he more important point is that if we and other industrialised economies DON’T take action to mitigate our own greenhouse gas emissions, then China and other developing countries are highly unlikely to act, especially not soon enough to avert warming that would otherwise be avoided.

So doing nothing would really be shooting ourselves in the foot.

Really, your argument doesn’t stack up. You could use it to justify doing nothing about just about anything, from dumping toxic waste in the sea to child pornography. You know, some foreign country is going to do it anyway, so what use will it do regulating it here?

Anyway, I see no reason to believe that China, India etc will simply ignore the global warming problem indefinitely. They are facing some strong economic imperatives at the moment but they’re not stupid.

Your question: “what is the optimum climate for the planet – the Ordovician, Cambrian, early or late Holocene (you can name your own if you like) and why?”

My answer: I much prefer things the way they are now compared with what they’ll be like if anthropogenic global warming is allowed to continue. These are our choices for next few centuries at least. Any others you might care to look up on Wikipedia are irrelevant.

Your question: “And Barry, if Australia shuts up shop and we reduce our so called ‘carbon pollution’ to zero the planet will cool by how much?”

I would like a scientist’s answer to this one too, because as far as I, a non-scientist can tell, the quesiton is based on a false assumption.

As far as I can tell from the literature, the world will continue to warm no matter what we do, because of the ongoing effects of earlier increases in greenhouse gas concentrations. Even if all humans, Chinese and Indians included, died tomorrow and the cars and power stations fell silent, global average temperatures would continue to rise for a long, long time due to feedback effects.

That means we can only choose how much further warming we create beyond what’s already locked in.

This is such a dreary prospect I would very much like Professor Brook to tell me I am wrong!

Over to you, Prof.


“Anyway, I see no reason to believe that China, India etc will simply ignore the global warming problem indefinitely.”

Perhaps – however the Indian Government has quite clearly stated it intends to continue building coal fired power stations and develop industry at an accelerating rate in order to relieve the desperate poverty of its people.

The Indian Government’s ‘National Action Plan on Climate Change’ states that “India needs to substantially increase its per capita energy consumption to provide a minimally acceptable level of well being to its people.”

44% of India’s billion or so people do not have access to electricity whilst 27.5% live below its rather meagre poverty line.

Therefore it’s quite clear India’s ‘strong economic imperative’ is to ‘develop’ at an accelerating rate.

Their one caveat is that they will try not to exceed the current per capita emissions of the developed world.

The Indian National Action Plan also finds “no firm link” between anthropogenic CO2 emissions and climate changes observed on the sub-continent.

It reports that some parts of India have warmed by 0.4 C in the past 100 years and other areas have cooled; similarly rainfall has increased in some areas whilst other parts of the country has slightly less.

So there is little chance India will follow Australia or anyone else into a so called ‘carbon pollution’ mitigation scheme.

Given the billion people in India currently only pump out 5% of the average person in the ‘developed world’ me thinks your version of the future Gaz is getting more dreary as we write.


Just saw Wal King from Leightons on Lateline talking about various things including climate change. They expect to spend 6 million over the next 2 years on accounting alone. Just what the world needs is extra cost centers that don’t add one iota to productivety or efficiency.

I subscribe to the theory that trying to wind back CO2 emmissions with taxes and such like is going to prove costly and ineffective. We may be better off spending money directly on issues as they arise rather than squandering trillions (worldwide) trying to slow CO2 output by a few percentage points.

Since the science community can’t make up its mind on Climate Change and the models did not predict the cooling of the planet over the last ten years …perhaps we need to be a little less alarmist. After all medieval physicians were convinced that the letting of blood cured annemia.


KImbo: you might want to take sophomore statistics, i.e,., that talks about time series, linear regressions, and significance, before you talk about cooling.

Alternatively, tamino, at Open Mind, is an expert who give wonderful tutorials on such topics, as in Garbage is Forever or more generally

The models *predict* a warming trend over multiple decades. Any noisy time-series will have shorter periods that go opposite a significant long-term trend, and the model runs do that, although they can’t predict El Ninos, volcanoes, etc, so they can’t predict exactly what any few years will do.

In any case, when properly computed (linear regression), any trend that is both long enough and strong enough to be statistically significant. EVEN IF YOU START WITH THE 1998 EL NINO, it’s still an upward trend, if you do the math right.

Do you think there is no warming because the temperature at your house cooled between noon and the following midnight? If not, how do you know how to compute a significant result? {A: good statistics methodology]

Seriously, you might want to read the short, classic book by Darrell Huff called “How to Lie With Statistics”.
You’re believing people who are trying to fool you…


PeterW said: “And Barry, if Australia shuts up shop and we reduce our so called ‘carbon pollution’ to zero the planet will cool by how much?”

It very much depends on how we do it – if it is through leading the world in R&D and implementation of large scale renewables, potentially PLENTY. I’ll talk more about this in my lecture 5 of Climate Change Q&A. Gaz, I hope that is a sufficient answer until my seminar arrives and I get to opine a little longer on this key point.

PeterW said: “what is the optimum climate for the planet – the Ordovician, Cambrian, early or late Holocene (you can name your own if you like) and why?”

It depends – if we are talking about a climate for which modern civilisation has developed around, then it is the one that has existed over the last few thousand years. In the long term context, life will go on and it is not the total temperature change that matters so much as the rate of transition from one planetary state to another. That rate of change is now in hyperdrive. Read my comments on extinctions for more details.

John Mashey – spot on re: climate model predictions – I’ll be talking about this misconception between what a mean prediction and a stochastic realisation tell you, in lecture 3 of my seminar series.


Barry Brook says …… “This includes predictions of warming made decades before it happened (that is, validation)”.

This is funny stuff, Barry. Is your validation one of AGW or is it just the ordinary boring old eternal natural climate modulation?


Is your validation one of AGW or is it just the ordinary boring old eternal natural climate modulation?

It also includes predictions of stratospheric cooling, which indicates the warming is due to less radiation escaping to space, consistent with our physical understanding of how CO2 works as a greenhouse gas.

Fun stuff – not funny stuff – science is like that.

Nice to see the denialist trolls show up in droves here. Displays of ignorance do wonders for your cause, dude.


So Dhogaza you sidestep the assumptions of the model and just go on making claims for it. Time to backtrack to the start.

What are the assumptions behind the claim that doubling-CO2 leads to an initial 1 degree increase in temperature and the further claim that this comes from basic radiative physics.

Obviously there must be heroic simplifying assumptions and massive aggregations going on here. What are they?

[Last line edited to remove personal abuse – last warming Graeme, do this again, and you are banned]


Dhogaza, have a look at the three major volcanic events, Agung in 1962, El Chichon in 1982 and Pinatubo in 1991 in these charts and tell everyone what you FIND. …. because it is find and ye shall seek. NOT your seek and ye shall find yourself funny stuff.


John Mashey, with your claim to have the skill set, let me ask you for your honest personal thoughts on a 30 year trendless Southern Hemisphere temperature chart where the data came from UAH. Are you able to do this critique? OR …. Perhaps just tell me what i’m supposed to be seeing here with these temperature graphs that should make me feel alarmed.


Someone here calls me a denialist troll and a dude with “Displays of ignorance” .

Dear moderator …. people calling me names does not mean all that much other than a bit of funny stuff but what is this you say to another poster? “[Last line edited to remove personal abuse – last warming Graeme, do this again, and you are banned]”


Dhogaza, have a look at the three major volcanic events, Agung in 1962, El Chichon in 1982 and Pinatubo in 1991 in these charts and tell everyone what you FIND

One thing you’ll find is that, despite what denialists claim, putting large amounts of shit into the atmosphere *can* affect global temperatures…


Keiran #21 asks John Mashey “Perhaps just tell me what i’m supposed to be seeing here with these temperature graphs that should make me feel alarmed.”

Well, I think I’ll just butt in here.

You should be alarmed about two things.

First, the graphs in the link have dotted lines through them, inviting the viewer to conclude the trend is flat. Hence, Keiran refers to the data as “trendless”. Sucked in, Keiran.

The dotted lines are just lines drawn through zero. That’s all.

In fact, as anyone with a spreadsheet on their PC can work out for themselves, the linear trend over the full length of the global average data is upward, to the tune of 0.13 degrees per decade.

For those not inclined to do the numbers, just have a look at the graph of the global temeperature anomaly. Most of the early years are below the line, most of the latter years are above it.

No that I’d set much store by the estimated linear trend – after all, drawing a linear trend through a time series is really a test of the hypothesis that the value is a linear function of time.

And we know it’s a function, in this case, of a number of things, including solar activity, various disturbances like ENSO, ocean currents, concentrations of greenhouse gases and aerosols from human and natural sources (eg power stations, volcanoes etc), and the cumulative feedback effects of these things.

So working out a linear trend over this series may give us a statistically significant result (unlike over the latest 10 years, which show a slightly positive but not statistically significant trend) it doesn’t mean it should be accepted as a useful model of what drives global temperatures. Regressions can only tell you so much.

So, as well as the fact that the grpahs in the link are misleading, here’s the other thing to get alarmed about.

The denial crowd, after years of spurning models, are now trying to use a model to support their views – a really simplistic model that omits all variables affecting temperature anomalies and includes only one – the date – that doesn’t affect temeperature (unless all those molecules look at their calendars evey day and say “Oh my goodness, its July already – we must be 0.001 degree warmer!”)

The spurious claims that the “trend” is now downward is tantamount to a claim that global temperature used to be a positive linear function of time, for no apparent reason, and now, miraculously, it’s a negative linear function of time, also for no apparent reason.


Keiran, your challenge to dhogaza in #20 to look at this link…

… is a bit mystifying.

Just what do these charts show except that volcanoes cause temporary disruption to the underlying pattern which is clearly evident?

That pattern is a warming troposphere (shown in lower graph) and cooling stratosphere (shown in the upper chart) in the link.

As we know, this combination is the tell-tale signature of global warming caused by greenhouse gases.

Thanks for providing that link.


I am a bit concerned….
How can one come to a conclusion about weather and climate using data from 30 years…
Would it not be more appropriate to use data from a longer period of time, ie 10,000 years…
We can get this data, ice core sampling from both the northern and southern hemispheres…
There is data available from trees that have lived for over 1,000 years in both the northern and southern hemispheres…
Would it not be more sensible to include a longer time line, thus having an average that would be more suitable…
Another question to ask is, where is the data being collected for these graphs?
I am sure the readings within suburbs should be discounted, I live in a small town and as I have neighbours, the temperature here is always at least 1 to 2 degrees Celcius, above the weather stations, as they are about 4 kilometres from the nearest buildings…
This shows that the area I live in would demonstrate global warming, yet the temps that are recorded show the opposite…
Too many unknowns, too little questioning…


Dhogaza i know you can do better than just finding your toilet problems in these charts. Please just try a little harder to describe scientifically if possible, what you have found out about stratospheric cooling. Perhaps Barry may like to comment … he is a climate scientist after all and this is his blog too.

It’s good of Gaz to help out but this is not a challenge unless of course you are challenged. i’ll just remain unalarmed and patient until JohnM makes his appearance because he is the alarmed expert with the skill set.


Kath -26

If you download the Power Point presentation and the podcast of the first of Prof Brook’s climate change seminars “Is the Earth really warming” you will get the answers to these questions. I found the presentation easy to follow for the layperson and the more scientifically minded. He has a “seminar homepage” at the top of this blog which sets out the other topics he plans to discuss in future seminars.


Gaz, while we await for the alarmed JohnM to make an appearance, may i comment on your chart reading behaviour. You are critical of the “dotted lines” in one set of graphs i.e. the trendless SH temps … inferring that they are meaningless and meant to confuse … hence you say something naive like “Sucked in, Keiran.” However with the stratospheric cooling graphs we have the same dotted line and you say the opposite with “Thanks for providing that link”. It’s as if, as i suspect, that your behaviour is search and ye shall find yourself with great success. That is very easy work and the exacto opposite to find and ye shall seek. Can you try again with the stratospheric cooling graphs to actually find something that is scientifically meaningful.


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