We Reckon Scientists Feel 95% Certain, But Don’t Ask Us How

28 Sep

The UN IPCC released its 5th Summary For Policy Makers yesterday.

From TIME magazine:

95%. That’s how certain the hundreds of scientists who contribute to the Intergovernmental Panel on Climate Change (IPCC), which released the first chapter of its fifth assessment on global warming this morning, are that human beings are the “dominant cause of observed warming” that’s been seen since the mid-20th century.

In science, which almost always speaks in probabilities, that’s about as clear as you get.


But how exactly is that “95%” certainty figure arrived at?

Professor Judith Curry explains (underline/red is mine):

I tried to figure out how the IPCC AR4 came up with the ‘very likely’ (90%) confidence level for the attribution statement…

[TBI: that is, how did they come up with the % “confidence” level for the previous IPCC assessment]

The IAC Review of the IPCC recommended the following:

Chapter Lead Authors should provide a traceable account of how they arrived at their ratings for level of scientific understanding and likelihood that an outcome will occur.

The IPCC uncertainty guidance urges authors to provide a traceable account of how authors determined what ratings to use to describe the level of scientific understanding (Table 3.1) and the likelihood that a particular outcome will occur (Table 3.3). However, it is unclear whose judgments are reflected in the ratings that appear in the Fourth Assessment Report or how the judgments were determined. How exactly a consensus was reached regarding subjective probability distributions needs to be documented.

Yesterday, a reporter asked me how the IPCC came up with the 95% number.  Here is the exchange that I had with him:

Reporter:  I’m hoping you can answer a question about the upcoming IPCC report. When the report states that scientists are “95 percent certain” that human activities are largely to cause for global warming, what does that mean? How is 95 percent calculated? What is the basis for it? And if the certainty rate has risen from 90 in 2007 to 95 percent now, does that mean that the likelihood of something is greater? Or that scientists are just more certain? And is there a difference?

JC:  The 95% is basically expert judgment, it is a negotiated figure among the authors.  The increase from 90-95% means that they are more certain.  How they can justify this is beyond me.

Reporter:  You mean they sit around and say, “How certain are you?” ”Oh, I feel about 95 percent certain. Michael over there at Penn State feels a little more certain. And Judy at Georgia Tech feels a little less. So, yeah, overall I’d say we’re about 95 percent certain.”  Please tell me it’s more rigorous than that.

JC:  Well I wasn’t in the room, but last report they said 90%, and perhaps they felt it was appropriate or politic that they show progress and up it to 95%.

Reporter:  So it really is as subjective as that?

JC:  As far as I know, this is what goes on.  All this has never been documented.

Got that?

The UN’s own official InterAcademy Council (IAC) review of the IPCC’s procedures and processes for their previous assessment report admitted that even though the IPCC “urges authors to provide a traceable account of how authors determined what ratings to use“, nevertheless this did not happen —

it is unclear whose judgments are reflected in the ratings that appear in the Fourth Assessment Report or how the judgments were determined.

And the IAC admitted that the IPCC provided no documentation to show how the supposed “consensus” view of the subjective judgments of hundreds of individual scientists with regard to “certainty” was actually reached —

How exactly a consensus was reached regarding subjective probability distributions needs to be documented.

In effect, this is what the IPCC is really saying about the “certainty” of scientists contributing to its assessment of the present state of climate science:

“Trust us. We reckon the scientists — collectively — feel 95% certain. But don’t ask us how.”


13 Responses to “We Reckon Scientists Feel 95% Certain, But Don’t Ask Us How”

  1. bushbunny September 28, 2013 at 1:15 pm #

    Their prediction is by 2100 the planet will be 2 C warmer than today? Really, caused by human activity. Now if the planet cools in between times, that 2 C increase will be welcome. They are frauds, and all that money given to alarmists, including Tim Flannery and Co., has been wasted. We can not predict future temperatures, and we only need one big volcanic eruption in between times, to cool the climate and mess up the atmosphere. So they are grasping at straws. Gladly we should try to work for sustainability as far as growing food, but selling land to Indonesia is not the solution. If the planet is heading for more cold weather our ability to grow food will be under some kind of stress. And increasing population in third world countries will be hit hard. And we are near the ring of fire, so SE Asia and East Asia are vunerable from volcanic eruptions, etc. 2 C is nothing. But rain fall is important anywhere.

    • The Blissful Ignoramus September 28, 2013 at 1:22 pm #

      I agree BB. It amazes me sometimes, that so many folks live under a cloud of subconscious anxiety generated by mere propaganda about a supposedly “dangerously” warming climate … and yet, are completely ignorant of the far more real dangers of our living on/near the Ring of Fire.

      • bushbunny September 28, 2013 at 1:53 pm #

        The thing Blissful, is that there are undersea active volcanoes, especially under the Antarctic and Mediterranean. There is a volatile trench off the coast of New Zealand, and if that collapses it will cause a Tsunami that will affect parts of SE and E Australia. Hopefully it will remain stable, but we can’t control the tectonic plate’s movements. We also have dormant hot spots in Australia in Victoria. One eruption was 5,000 years ago. So it can’t be classed as extinct yet. And New Zealand has a lot of seismic and volcanic activity. Now NASA are planning dragging some asteroids around the moon so they can study them, I hope they know their physics well and our gravitational pull doesn’t affect the moon or the planet. I think there are some mad scientists around, who are keen of earning the grants without forethought?

  2. Shawnster September 28, 2013 at 3:41 pm #

    There seems to be a lack of science and an abundance of faith in “trust me I’m a climate scientist”. I could extrapolate the last census and say in the year 2050 there will be 4M homeless in Australia so we need to build more houses immediately via a tax on existing homeowners.
    Or based on my Excel spreadsheet model of warming using a 6th order polynomial and spline fitting of regression data of the past 200yrs of climate data there will be a warming around the blue Mountains of 6C in the next 90yrs. Who can say I’m right or wrong. I will be dead before you call my bluff.
    I don’t care as I get funding from Tim Flannery Organisation (aka taxpayers) and I dearly want to keep playing with this modelling and become a world known “expert”. I bet that the roman empire had lots of pontificates of all sorts just prior to the fall because they had them for 500yrs before saying the empire will expand etc.
    Personally I would worry about more higher priority things like America starting WW3 or the Zionist bankers crashing the fiat system and sending us to the poorhouse.
    When you throw a rock at a cat it only sees the rock, when you throw a rock at a dog it only sees you throwing it. I am not advocating animal cruelty of course but the thing is there are plenty of rocks being thrown and we need to wise up to the important ones that might knock us out not the flyrock that is just annoying.

  3. Tomorrows Serf September 28, 2013 at 4:10 pm #

    Didn’t the Greenland ice sheet EXPAND by 60% between Aug 2012 and Aug 2013?? Or was I hallucinating??.

    Didn’t the preliminary reports indicate that the “climate scientist’s” models were wrong by 50%.
    Isn’t it now fairly mainstream that there has been NO warming for the last dozen or so years??

    So how in hell can these academic “snouts in the trough” come out with yet more BS about man-made global warming/climate change being an issue??

    And Flannery and gang are going cap in hand to “the private sector” (read Goldman Sachs) for further funding to continue their “vital work” (read propaganda)

    Yep, they’re now 95% certain about the need to keep the climate change scam and their cushy gigs(and salaries) at various universities going.

    And with the help of the ABC, who has pushed hard all day, that the science is now REALLY settled. That’s it. Nothing more to say. Disagree with us and we’ll call you “a DENIER!!”

    Because they are 95% certain..

  4. Ross Johnson September 28, 2013 at 5:27 pm #

    http://www.geocraft.com/WVFossils/Carboniferous_climate.html I was suspicious about AGW in 2008 after viewing this article. The graph on this link shows the concentration of CO2 compared to temps over millions of years and there is no correlation between temps and the amount of CO2 the in the atmosphere. In fact we had a severe ice age when CO2 levels were 12 times the present.

    Using Tim Flannery’s science logic,the Oceans then should have been boiling.

  5. mick September 28, 2013 at 8:49 pm #

    What else would one expect when you get people with shut minds? Little more than running around seeking any distraction which may make them feel better. I find it sad that people seeking credibility try to trivialise and poo poo what they do not understand and then claim that the issue is a scam run by the rich.

    >>TBI: Opening with an insult = negative credibility. Subsequent sentences little more than additional ad hominem … zero evidence, zero substance, just insult and logical fallacies.

    Tomorrows Serf: check out the following link as you are displaying the common misunderstanding of those who seek to rubbish climate science:


    The area covered by the ice shelf is seasonal. It increases and then decreases. IT IS NOT A LINEAR CHANGE. But what is understood is that the area covered is the 6th lowest. And what is not discussed is that the thickness of the ice sheet is decreasing every year. Check out the link:


    “Sea ice thickness likewise showed substantial decline in the latter half of the 20th century (Rothrock et al. 1999). Using data from submarine cruises, Rothrock and collaborators determined that the mean ice draft (the ice extending below the water surface) at the end of the melt season in the Arctic decreased by about 1.3 meters between the 1950s and the 1990s.”

    There is one anomaly though. Whilst the Arctic ice coverage is decreasing the Antarctic is increasing somewhat. The reason for this is not clear but it is not signalling a nil change.

    >>TBI: Right. An “anomaly”. There are LOTS of anomalies. The science is inconclusive. The real world evidence does NOT support the alarmist predictions made, with intent to scare politicians and the general public into accepting / supporting the financialisation of nature. Bad news for alarmists Mick — polls worldwide indicate that the public is no longer buying the Big Scare story.

    BI: You need to take a course in statistics. Scientists talk in terms of probabilities and this is not limited to climate change science. The terms used are one, two and three standard deviations. “Very probably” (95%) = 2 standard deviations. “Almost Certainly” = 3 standard deviations. Its got nothing to do with scientists casting lots. Its got to do with the fact that there is always some doubt no matter how small. I know that your financial mind will find this difficult to comprehend but its just the way it works. I guess that is why you also find it difficult to come to grips with the fact that changes are non linear even though a trend is well and truly established.

    >>TBI: This little lecture does not address what was written in the post. Do you actually have a point to make? Do you dispute what is actually written in the blog post? Specifically, do you dispute the words quoted from the UN’s “independent” review of the IPCC’s processes and procedures vis-a-vis the IPCC’s failure to show, much less document, the ‘who’ and ‘how’ of their claims re judgment of scientific “certainty”? If so, explain, with direct reference to THE ACTUAL POINT of the blog post.

    All in this forum need to forget about the great conspiracy. It is nothing of the sort.

    >>TBI: Straw Man.

    If the consensus of 800 scientists means nothing

    >>TBI: I am presently writing another post that directly addresses this alleged “consensus”. For now, did you know that the previous IPCC assessment claimed 2,000 scientists participating? And for the latest one, only 800 … why do you think that is?

    then what can I say as these people are not the village idiots and nor are they out to defraud the world. As I have said on many occasions, this game is still in play. Perhaps when the water is around your knees you will. all too late, concede that YOU ARE WRONG.

    >>TBI: *sigh* Mick, do you realise how dumb those two sentences appear? First, you say “this game is still in play”; based on your many previous statements, this once again implies that you are claiming to be open minded. But then, in the very next sentence, you speak of “when the water is around your knees”, clearly implying that you are quite fervent in your belief re rising seas, thus contradicting yourself re your previous sentence.

    • Tomorrows Serf September 29, 2013 at 7:52 am #

      Thanks Mick for the nsdic.org data(another publicly funded organisation staffed by eminently qualified, bearded personnel with their collective “snouts in the trough”) about Arctic ice sheet coverage over the last few years.

      Seems to pretty much corroborate what any rational observer knows instinctively. i.e. climate changes are random and natural. (agreed- non linear) Linking such a natural occurrence to CO2 concentration is a stretch.
      I like Ross Johnson’s article: (Thanks Ross)


      To save you the time, let me summarise in one sentence.

      Over hundreds of millions of years, the climate has continuously changed, (hotter and colder) sea levels have varied (higher and lower) Co2 concentrations in our atmosphere have been more concentrated (1500 ppm- 286-300 million years ago) and LESS concentrated (350ppm-today), …………

      Anyway Mick, I’m sure you get the gist. Just pay your Carbon Tax inflated electricity bill and be happy.

      The Banksters appreciate it.

      And as for “the need to forget about the great conspiracy”, no worries. It’s already forgotten. You’re probably right.

      Now, what time is “Dancing with the Stars” on????

      • mick September 29, 2013 at 3:26 pm #

        For the uninformed, the rednecks and those who have their fingers in their ears and their eyes closed:


        Sorry Tomorrows Serf but you are wrong. The graph on the above link (be bothered to look) does something interesting around 1950. I guess you and others on this blog will claim more conspiracy theory. It was rigged!! Banksters did it!! But the smoking gun is there to see for those who want to understand that the planet is in a state of flux. How much none of us knows. And whether or not there are ecological systems to fix what is occurring is also not known. What is obvious to anybody other than fools is that something is going wrong……and it ain’t banksters.

        Seriously mate, it is easy to be fooled and to be led. The election campaign which just ended should tell you that with the result already decided well before the event. Instead of sticking to your conspiracy theory ask yourself if 800 scientists could be colluding to deceive the population of the planet and if the growing body of evidence could really be manufactured and misrepresented. If you think so then you make the conclusion that 800 highly educated and in many cases highly ethical people are ‘making it up’. I don’t think so.

        And last of all look at the credibility of the deniers: oil and coal funded ‘studies’ (for want of a better word), mouthpieces like Mockford and the Murdoch Press pushing the barrow of big business. These ‘sources for want of another word have no credibility and those who regularly put them forward lose their own credibility as well as appear foolish to all other than the feeble minded.

        We live in an interesting world.

        • The Blissful Ignoramus September 29, 2013 at 3:50 pm #

          “the planet is in a state of flux. How much none of us knows.”

          That is what we sceptics say.

          “The election campaign which just ended should tell you that with the result already decided well before the event. Instead of sticking to your conspiracy theory…”

          Er … Mick. Your own first sentence here is, essentially, a conspiracy theory. Do you realise that? But you rail against others (in the very next sentence, indeed) for being conspiracy theorists. Pot calling kettle black.

          “..ask yourself if 800 scientists could be colluding to deceive the population of the planet..”

          Noone here has said that they have.

          “if the growing body of evidence could really be manufactured and misrepresented.”

          Mick, it HAS been misrepresented. This has been proven, over and over and over again. There is no “consensus”. The science is NOT “settled”. Even the IPCC has admitted (though tried to hide it, in a footnote) that their 800 contributing scientists cannot “now” give a best estimate of equilibrium climate sensitivity, because of a “lack of agreement”. But nowhere is this critical fact highlighted, in a title, or a headline, in the IPCC’s report. Instead, it is hidden away, hoping noone will notice it. THAT IS misrepresentation of the science. This is unarguable.

          “If you think so then you make the conclusion that 800 highly educated and in many cases highly ethical people are ‘making it up’.”

          No. This is NOT what I and/or others have said. See above comment.

          “And last of all look at the credibility of the deniers: oil and coal funded ‘studies’ (for want of a better word), mouthpieces like Mockford and the Murdoch Press pushing the barrow of big business.”

          1. This argument is known as ad hominem fallacy. Focus on the scientific evidence itself; not your own prejudices.
          2. Who is “Mockford”? If you can’t even get people’s names right … ?
          3. You can’t have it both ways Mick. On the one hand you want to believe that Big Business rigs elections, has Obama as a “puppet”, and funds AGW sceptics. But then, on the other hand, you don’t want to believe that Big Business rigs wars, or finances pro-AGW information, even though the biggest business of all — banking/money — has the most to gain (ie, the biggest incentive) from the “solution” constantly pressed forward to supposedly stop “dangerous man-made climate change” (ie, global carbon derivatives trading markets).

          • Tomorrows Serf September 29, 2013 at 4:14 pm #

            Thanks BI for responding. I couldn’t be bothered any further.

            I can’t work out where Mick is coming from. Do “internet trolls” REALLY exist? Who could be bothered…

            Any way, Mick confuses me. But I don’t like the ad hominum attacks. Clean up your act, Mick. We’re all trying to keep things civil and productive.

            • mick September 29, 2013 at 8:25 pm #

              Perhaps read some of the posts which have come my way.

              Internet troll? Absolutely not. But neither am I a programed puppet. i thank the Lord that I was born with the intelligence to discriminate between possibility, evidence and conspiracy rants.

              >>TBI: As has been pointed out multiple times, you have presented belief in “conspiracies” yourself (Murdoch, rigged Oz election, Obama a “puppet” of Big Business). You just don’t like it when others infer the possibility of collusion vis-a-vis banksters and the global warming juggernaut.

              Perhaps look in the mirror.

              “The truth will set you free”.

              BI: Have you heard the old paradigm about ‘divide and conquer’. I find it interesting that when you fail to win an argument by intimidation you resort to trying to pick a flaw and then generalise this back to the discussion to try and destroy credibility. Sorry mate but not working.

              >>TBI: (1) What exactly has the strategy of “divide and conquer” got to do with my responses to your comments? Nothing. (2) What “intimidation”? The only intimidation is that you find it intimidating to have your beliefs challenged, and your arguments shown up for what they are — logical fallacy-ridden, internally contradictory, inconsistent, out-of-context, off-topic, evidence-free noise; full of abuse, never addressing the evidence presented, and (often) not even addressing the point.

              As I said before play the ball not the man. The trouble is you are unable to play the ball because your rationale is tainted and has little or no credibility. Lacking credibility means that one has to resort to the above behaviour.

              >>TBI: Er .. Mick, it is not you who has said to me, play the ball, not the man. It is I, who has said it to you. Many times. Why? Because you persistently use abusive labels, and insults directed at those arguing against you, while never addressing the actual evidence presented. *shakes head*

              This blog has been interesting. For all the good you have done by exposing the banking system you soil yourself when you fight the dirty fight and refuse to see what is. Whilst I will never appease drones who are unable to accept facts I have done my best to expose the lie for what it is.

              >>TBI: You have presented no facts. Only abuse, and logical fallacies.

              Whilst you seek to turn the argument back on me I state that your belief that a global conspiracy is in play is wrong.

              >>TBI: Straw Man. Again.

              My perception is that individuals seek to shore up their positions via bought political and media representation. Nothing more. Tell me that the world’s largest corporation meet in boardrooms to plot politics and I’ll have to suggest that an institution may be more applicable.

              >>TBI: (1) Do you even know what the world’s largest corporation is? How do you define it? (2) Noone has said this. Once again, you raise a Straw Man, and argue against it. EDIT (3) What is that act of “individuals seek(ing) to shore up their positions via bought political and media representation“, if not an act of collusion (ie, “A secret agreement between two or more parties for a fraudulent, illegal, or deceitful purpose; connivance; conspiracy“)? Seriously, I have to wonder if a big part of the problem is that you simply do not understand the actual meaning of many of the words you read and use.

              I’ll leave your few disciples to themselves. They are beyond help. Good bye. mick.

              >>TBI: Yet again, you attempt to insult and belittle the author and host, by stating your assumption that this blog has few readers. I guess you’re right … 10,000-12,000 unique visitors a month is only a “few”. Thank you for your public commitment to leave me/us alone from now on. I will truly appreciate the reduction in time spent moderating comments.

  6. Kevin Moore September 29, 2013 at 9:14 am #

    In response to the above pro establishment article, a commenter had this informative comment –
    Is this a joke? You have heard a summary prepared after NGOs and governments argued for a week in Stockholm to reflect their government positions. Or don’t you know about that.
    You have not read the report, the AR5, which were we told would be released this month, but now will not be released until 2014. The AR5 Second Draft report was leaked in December 2012; the Second Draft means that no new info may be included. (Google and read it) What THAT report shows is that the observed data–the actual satellite and land temperature measurements–is far less than the models. A peer-reviewed graph in it shows that there has been no increased warming since 1998.
    Look at the graph here, and tell me if what you are hearing is the truth. LOOK AT IT.
    Remember that the “modern record”or “recorded history” they are talking about started in 1979.

    Chemtrails/climate change/carbon taxes/911 – a conspiracy theory?

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