Monthly Archives: February 2014

A matter of trust?

In previous post it was all about the alarmist statement that rebutting one claim by “climate contrarians” is like a whack-a-mole game: an ever repeating job. Apparently the solution seems to be: let’s ban them skeptics, then we can continue to save the world. On his blog the author mentioned that he didn’t want to start a fight, but just end one (by excluding those who disagree in the media). Welcome to our world.

Via Twitter I came across a similar construction, but with a slightly different approach: Climate change science, the consensus, and a matter of trust by Graham Wayne (he also writes for, ahem, “Skeptical” Science).

The post started a bit long-winding that there is no trust anymore in this society, but hallelujah, this is the good news:

One of the things I find most attractive about the scientific method is that it doesn’t require me to ‘trust’ scientists. Instead, there’s a more amenable and logical way to approach the issue – trust the work, the process, peer-review, the results and the repeatability of experiments. Not without some irony, we can also trust the competitive nature of science, for no scientist with an eye to his or her own success, to their place in the history of science, to the long-term value of their work and its merit, will subscribe to a theory or cite the work of others, if there is a reasonable chance that citation is wrong, that subscription is worthless.

Also here we have the argument that science (and at the back of the mind it is assumed: climate science), follow the scientific method and is completely trustworthy. It depends how one defines the scientific method. If it is the process of “observation, hypothesis, prediction and testing” they are in for a surprise. Of course it is always a nice thing to be able to assess a situation without knowing much about it, but is this assumption really true? Maybe, maybe not. In an exact science this certainly could be working, but Climate Science is not exactly an exact science. Peer review is not necessarily the best tool in a small group. The repeatability could also be an issue in a chaotic system, especially when not much long term data is gathered yet.

Sure there is no need to trust scientists if we trust the work. But aren’t those scientists doing that work in the first place? Why the hammering on this “scientific method” when this has no real importance in a post normal science? Why the emphasis on the competitive nature of science when the scientists avoiding the debate with those who are skeptic? Why hiding behind a 97% figure when there is unequivocal evidence?

The real irony is that there is no conclusive evidence yet that man is the dominant cause for the 20th century warming. But, but, doesn’t the IPCC have O V E R W H E L M I N G evidence that man is responsible? With a certainty of 95%! Coming from 90% in the last report. Isn’t that proof? That is an opinion of a group scientists. In the end that overwhelming evidence is circumstantial evidence, okay I admit, a lot of it. That overwhelming amount of evidence is needed because it is not possible to conclusively proof it. When there is clear evidence, why not just place it on the table for all to see? Why not facing skeptics head on? Wouldn’t that build trust?

Whack-a-larmism

It takes me by surprise every time I hear about “climate scientists are in the disadvantage compared to the skeptics”. It seems so out of touch with reality in which alarmists have almost a free podium in the mainstream media and employ tactics that wouldn’t be out of place in politics. With the same surprise I read the opinion piece of Simon Donner in the Vancouver Sun titled Scientists certain human activity causes climate change with the subtitle Pick and choose: Dealing with contrarians using dirty tactics is like a game of whack-a-mole.

At the heart of his statement is:

The majority of scientists follow the scientific method – a systematic approach to building knowledge. Starting in the 1820s, scientists began accumulating evidence, through the slow process of hypothesis testing and data collection, that adding carbon dioxide and other heat-trapping greenhouse gases to the atmosphere would warm the planet.

Now, after almost two centuries of research, scientists are as certain that human activity causes climate change as doctors are that cigarette smoking causes cancer.

On the other hand, many opponents of the scientific consensus on climate, like Tom Harris, author of the recent column Climate rhetoric undermines rational decision-making, and executive director of the International Climate Science Coalition, don’t need to play by the rules of science.

The whack-a-mole comparison was that rebutting one claim by “climate contrarians” gives rise to another, like a game of whack-a-mole. An ever repeating job and he got tired of it.

I heard these things before. More, it is something I myself believed before. In my believer years I thought that there was a invisible, powerful underground movement that employed dirty tactics against honest working scientists, making it difficult for them to make a dent with the public. Imagine my surprise when I found out that the debate was stifled by activists and political scientists who get almost exclusive attention in the mainstream media. By claiming consensus. By ad hominem attacks on skeptics. By making them look ridiculous/incompetant/unqualified. By not wanting to debate them on the science.

This opinion piece was specifically directed to Tom Harris. According to Donner, he made some ridiculous claims in an opinion piece “State of the Union climate rhetoric undermines rational decision making”, which are then demolished. No link to the article was provided, so I couldn’t check what Harris actually wrote. But Tom Harris himself had commented on the opinion piece of Donner and his arguments were well-thought and made sense. So this made me eager to find out who that Tom Harris was and why Donner had such a low regards of him.

Although I heard his name before, I could not recollect reading something from his hand. I became curious about what he really wrote in his article. I didn’t have to search long to find an article with the same title published beginning of February.

It confirmed my opinion on Harris. The article was about the use of rhetoric in the debate. Some terms in the debate can be misleading, for example “Carbon pollution” and “Greenhouse effect”. I heartfully agree with that. I also think that there are a lot of ambigue and misleading terms used in the climate debate, which make a genuine debate much more difficult. In the article Harris explained that “carbon” (a black, solid stuff) is not an accurate term when the real thing you want to describe is “carbon dioxide” (a transparent gas).

The reaction of Donner on this article was a bit weak. It focused on a couple sentences, ripping them out of context and then demolishing the “claim”.

The first rebuttal was the claim that Harris “suggests that carbon dioxide could not be a pollutant, because it is an invisible gas essential to plants”. That’s not even close to what Harris said. He did indeed say that carbon dioxide is an invisible gas essential to plants and he also said that it is a greenhouse gas and therefor has a (modest) influence on temperature. But he never said that is not a pollutant solely because it is essential to plants. Debunking an out-of-context claim is pretty easy.

Secondly, Harris claim that “Past ice ages demonstrate that climate change is normal” was countered by te statement that “the recent climate change is driven by human activity, and it is occurring at a rate not experienced in the history of human civilization”. While Harris was reacting on the Obama’s statement that “Climate change is a fact”. Of course it is. It has always been a fact and will always be a fact. The big question is how much our influence is within this change. In a situation were we only started with high quality measurements on the natural part a few decades ago, this could be more of a challenge than what Donner admits.

The last one was “global warming has been virtually non-existent during the past 17 years”. Donner claims that “the planet has not stopped warming” and that “during the past decade, more of that heat has gone into the deep ocean, due to natural cycles, so the atmosphere has not steadily broken global surface temperature records”. Well, that can be true, but this is still a hypothesis and not really supported by the observations, because there are not much observations of the deep ocean in the first place. And yes, there are some climate models that try to fill in the missing data. But model outputs are not observations, these are hypotheses that still have to be falsified. Nature is way more complex than the black/white vision of Donner.

Sigh. Dealing with these alarmist stories told with absolute certainty is as well like a game of whack-a-mole. 😉

But the conclusion was the most telling:

I agree. I’m tired of this game of whack-a-mole. We need to stop publishing the deliberately deceptive claims of contrarians like Harris, and get on with addressing the challenge of climate change.

Basically, we know everything we need to know, let’s shut down those who disagree with us and do the things we think we have to do. That is not a really a scientific way of thinking, but more an activist approach.

So not everybody plays by the same rules. That’s perfectly clear here, but now it is also clear which side doesn’t want to play by the rules and desperately want to stifle debate in order to do their own thing.

Pascal’s wager revisited

It is always interesting to find out how different people have different understanding of things. Recently I found a link to a video made by school teacher Greg Craven: A guy with a marker aims to make the global warming debate obsolete. The site that provided the link brought it as “an example of engaging and effective science communication“.

Well, that sounds promising!

According to the author it is possible to choose how best to act on the issue of Global Warming (he uses both Global Warming and Climate Change) without knowing something about the science of it. That is interesting. When I started looking at the global warming issue about five years ago, I also was searching for a way to find if the arguments about global warming were true or not. I found that in some cases this is possible (when certain logical fallacies were used), but in most cases it is necessary to know at least something about the science. I am a bit skeptical hearing him say no knowledge of the science is needed.

This is how it is presented: if we can’t be sure if global warming is true and we want to know what action to take, we can make a table in which we put the outcome of different possible scenario’s. On the left the question: “is Global warming true or false”? On top the question: “do we take significant action now”? From that outcome of these questions he claims it is possible to decide what is the best option to take right now.

Climate Change wager

Climate Change wager.

This is nothing new, I saw similar reasonings before. It looks very similar to Pascal’s wager. This says that “it is safer to believe in God, even if there is no proof that one exists”. Pascal’s starting point was also that it was not necessary to know something about the existence of God to know what do in our life. This is how Pascal saw it:

Pascal's wager

Pascal’s wager.

Pascal also wrote down the different outcomes of possible scenarios. These are the outcomes

    If we believe and:

  • God doesn’t exist: we lost some time worshiping and weren’t able to do things we probably would like to do → finite sadness (until we die).
  • God does exist: we go to heaven and are rewarded for our efforts with eternal bliss → infinite happiness (forever and ever).
    If we don’t believe and:

  • God doesn’t exist: we didn’t loose some time worshiping and did everything we liked without restriction → finite happiness (until we die).
  • God does exist: we go to hell and are punished with eternal misery → infinite sadness (forever and ever).

So if God exists, the reward and the penalty are huge (because they are forever). If God doesn’t exists, the reward and the penalty would be minor (because we have short lives). Therefor his conclusion was that it is better to believe in God because the outcome is better when we believe than when we don’t believe.

So far so good, but as I learned in school this wager is based on an array of logical fallacies and he cherry picked a bunch of assumptions that lead directly to this conclusion, therefor invalidating it. For example, in the wager Pascal assumed the God to be the God we know in this part of the world and that this is the “right” God. He also assumed that there is an afterlife and that believing in God is enough for eternal bliss and failing to believe will give eternal misery. Also that this God cares or is fair. That one can get away with calculated worship. Etcetera, etcetera. There are many others. A lot of books have been written about this wager.

As far as I know, the Craven’s wager has basically the same problems as Pascal’s wager.

It gives about the same outcomes as the Pascal wager. He adds that we can’t choose which row we want to be in, but we can choose in what column. He likens it with a lottery ticket. For example if we buy lottery ticket A then it will cost us a lot of money in both cases (we will ruin our economy whether global warming is true or not). But when buying lottery ticket B it is possible to have a rather nice reward if global warming is false, but a really nasty one if it is true.

Therefor he says that it is better to choose ticket A: we will loose money, guaranteed. But when we buy lottery ticket B, the outcome is much more uncertain: it is or extremely good (if climate change doesn’t exists) or extremely bad (if it does). So, if we want to avoid the extremely bad, we need to choose ticket A. In which we will have to pay a lot of money whether climate change is true or not, but if it is true we would survive it.

The author makes the suggestion for everyone to remake this for other outcomes (also the less extreme ones), but adds that whatever scenario you will choose, it will always come to the inescapable conclusion that ticket A will be better than ticket B…

But is this really true?

In analogy with the Pascal wager, this “inescapable” result is completely dependent on the smiley face in the bottom left quadrant; combined with the over-the-top dramatic scenario in the bottom right. If both scenario’s are taken as constants, the only sensible choice will indeed be ticket A. The over-the-top scenario of ticket B will overshadow the grim outlook of both scenario’s in ticket A. But I could imagine other scenario’s in which this is not necessarily the case and then ticket B might be much more interesting.

Let’s go through all quadrants and see what the range of possible scenario’s will be.

The only quadrant that we really can be sure of is the one on the top right. This means: we didn’t spend any money to prevent global warming, but it was not needed. Whatever scenario you choose, there will alway be a happy face in that quadrant.

The values in the three other quadrants will depend on the assumptions made and will be somewhere between the best case scenario and the worst case scenario.

In the top left quadrant he assumed: we spend money where it was not needed and we came into a (global) recession. That is the worst case scenario. The best case would be for example: we spend money, but we could afford it and spending it didn’t hurt us much.
All other options would be between those two.

In the bottom left quadrant he assumed that Climate Change existed, we took action and we came to the solution. That is in fact the best case scenario, not the worst as he assumes. Worst case would be: Climate Change exists, we did spend money on it trying to prevent it, but it didn’t work out (we spend it on the wrong solution, it wasn’t preventable anymore or whatever). In that case we would be with much less money and still facing the horrors of Climate Change. Like the victims of Haiyan who were unprepared for it.
All other options will be between those two.

In the bottom right quadrant he assumed that Climate Change existed, no action was taken and all the horrors of the world come at once and catapults us into oblivion. That is the worst case scenario. The best case scenario is that Climate Change exists, we took no action to prevent it and it was possible to adapt to it with not much effort.
All other options will be between those two.

Now we start all over and go for the two extremes (the real extremes, not the assumed ones):

  • When we take the worst case scenarios in all cases, we will likely choose ticket A. So far so good. That was also the conclusion of the author
  • But when we take the best case scenarios in all cases, we will likely choose ticket B.

In the end this exercise will learn us exactly nothing, except that the scenarios will depend on how one defines the assumptions for the different scenarios.

Just as the Pascal’s wager this wager it starts from a number of assumptions. For example that climate change is preventable by us, that we would be safe when we do something now, that the outcome of not acting is dramatic, that it is not possible to adapt and many, many more. Therefor the conclusion was skewed to ticket A.

This was a system assumed for those who have no knowledge of the science, but those are now presented with a one-sided presentation of the facts. But either way, my opinion is that when one starts from the premise that it is not necessary to know if global warming is true/false or if it is happening/not happening, then this table is useless to find out what the best option really is. Making this just a modern version of Pascal’s Wager, numerous assumptions and fallacies included.

Confidence is what we expect from the experts

itgoestoeleven

When listening to the alarmists panel in the UK Parliamentary Inquiry on the science of IPCC AR5, I noticed a clear difference to the skeptics panel. The witnesses in the alarmists panel were very sure about themselves. The science was clear. There was a consensus. Climate scientists were skeptical themselves and keeping science sane. There is uncertainty, but it is small and is accounted for. The models were reliable and could give valuable answers. They said all those things with much confidence.

How could there be such a large contrast with the skeptical panel? I think it certainly has to do with the role they are playing. As John Robertson said:

I like the idea that science tells us something and we have to agree because science says that is it.

Some sites made fun of this statement of John Robertson, but I think it is right in the heart of the issue. The politicians like simplicity from scientists. They like them to say if global warming is really happening, yes or no. If it changes our climate. If there is a need for action and what that right action then should be. There is no shame admitting that. For several decades now we are being told an extremely simple story:

We emit CO2 → Being a greenhouse gas, it warms our atmosphere → Bad things happen.

It is simple and straight forward. So we also expect the same confidence from those who study it. They are considered the experts. This means they could not possibly backpedal now and say there are still huge uncertainties, that the models were way of with reality. That is what the skeptics are saying and it doesn’t serve them well. Therefor they avoid the inconvenient parts like the standstill in temperatures, the many uncertainties they face, the failing models,…

Let’s face it. People are attracted to confident statements from those they consider the experts. This is how issues are communicated most efficiently. That’s why the “consensus” is so important and alarmists put a lot of effort into declaring it. It is not because it is part of the scientific methods or important in science. It is because people, especially those who don’t want to look into the issue, are biased to the side of the largest group. Thinking that “They can’t all be wrong”.

But isn’t that a problem for the scientists involved? Sure, it is. If their predictions/forecasts/projections don’t materialize, they lose credibility. But the projections are way ahead in the future. Many of the projections of the IPCC are for 2100, more than 80 years ahead of us. There is no doubt all the current experts will be long gone before any of those predictions can be verified or falsified. So at this point it doesn’t even matter what they project.

But shouldn’t we respect our experts? Sure, but we should keep being skeptical, especially in areas where there is little data and high uncertainties. The fact that scientists try to declare a consensus and high certainty in a complex system with little data should be a clear warning sign.

The alarmists panel in the inquiry knew what was being expected from them. They delivered. They likely will be asked again.

One candle to blow

oneyear

Exactly one year ago today, on the 13th of February 2013, I published my first ever blog post. Since then 85 posts were written and published, this is number 86.

Time to look back to one year of blogging.

My initial intention was to have about one post per week. Even that I was not really sure I could manage. I tought being happy if I got to about 50 posts per year. Reality was a bit different. Indeed, it started a bit hesitant with 3 posts per month, but around post 35 I got the hang of it. It was at the time that the IPCC report came out and for a limited time I started to churn out posts almost daily. This eventually culminated in a steady pace of about 10 posts per month from October till now. I found a rhythm. Posting more frequent would be not practical, unless I make my posts smaller (I think I make my posts much too long).

I didn’t make it myself easy by writing in a language that is not my mother tongue and although I work in an international environment which demands switches from one language to another on a frequent basis, details can get lost. Although I use a spell checker to filter out errors, mistakes like quite/quiet, where/were will keep popping up. In my focus on the contents I gloss over them, so does my spell checker. I keep on finding such mistakes in older posts, even now. But on the positive side, it improved my knowledge of English spelling tremendously.

The number of views is nothing to write home about, but it is getting better. Since November 2013 there is a steady increase and February started rather strong. So there is hope this trends continues. On the other hand, I have the impression that not all visits are recorded. I sometimes find posts shared without being viewed yet or post with more shares than views. Readers probably view posts in the WordPress Reader and share and/or like from there.

Most popular post (besides the home page and About) were:

  1. The making of The Hockey Stick (April 17, 2013)
  2. (Over)blowing in the wind (February 13, 2013)
  3. Attribution certainty differences between AR4 and AR5 (September 30, 2013)

Most of the views came from United States. Somewhat more than half from United Kingdom. Half of that from The Netherlands. About the same from Belgium (but most are mine while exploring WordPress functionalities). The rest is far away from that, but Canada and Australia are rising strong in the last months.

I also see the presence of my posts in aggregator blogs like for example The Climate Cult, where visitors can view all my posts without having to visit this blog. There were also 3 reblogs of a post on other sites. So I have still some hope that there are more people reading my post than what I can see.

To my surprise, there are now 22 followers. Didn’t see that coming. The same thing with the number of comments. I never anticipated so many. Thank you all.

Also a big thanks for the likes. These were the most comforting when it got though in face of the limited views and they gave me the courage to go on.

For those who are reading, thank you for passing by and I hope you will come back in the future.

The increasing confidence seems to be very hard to explain

The UK parliamentary Inquiry of Energy and Climate Change Committee into “the science” of UNIPCC AR5 was a very interesting event. This in several ways. There was of course the fact that this time there was a alarmist panel and a skeptic panel that were questioned. On blogs and articles I heard a lot about the second session, the one with the skeptics. But I was more interested in the first session. It gave me a lot of ideas, so probably some later posts about things that caught my eye.

In previous post I spend some time on the question why there is now increased confidence in human influences and the answers were puzzling.

Why was I so interested in that little question? Earlier, I was confused by the statement of the IPCC that they had more confidence that humans caused the warming in the last 60 years. In the media I could not find a clarification about this, only a rehash of the statement. Now, in this UK parliamentary Inquiry, I came across an insider that seems to give some more background information. That insight could indeed fit the IPCC statement, but when looking into it, it also made it meaningless.

To recapitulate: the statement was that we can have more confidence that the human influence is towards warming because the higher confidence that the cooling influence is less than previously thought. Meaning the overall anthropogenic influence is warming. As I said before I can agree with that, but it doesn’t say nothing about the amount of anthropogenic warming. It could be more, true, but it could also be less or even the same.

This is what puzzled me: the inquiry was set up in order to inform policy makers about the science in the IPCC AR5 report. The answer given was to an interesting scientific problem, but was not aligned to MP’s, at least not without additional explanations. Policy makers don’t want to know that net anthropogenic influence is towards warming, they probably start from there already. What they want to know is how much that influence is.

Further in the inquiry there was another attempt to pose the exact same question. According to the transcript:

[Graham Stringer]
Going back to some of the questions that John asked previously, one of the things that puzzles me about the greater confidence that the IPCC now has in their analysis and predictions is the hiatus in increasing temperature was not predicted, and yet you have greater confidence as that particular prediction was wrong. I am a chemist, not a mathematician and so I am treading somewhere where I fear to tread, but my understanding of Bayesian analysis is that when you have high confidence of something and you miss your target, you should have less confidence, not more confidence. Why do you have more confidence?

[Professor Sir Brian Hoskins]
I was not part of it, so I will not say “we”, but let me say that the models were not in the position to predict the hiatus, because that would have been an initial value problem where they would have needed the observations over the whole depth of the ocean as well as more of the whole climate system to start the model off, like a weather forecast if you like. That information was not available and so they were just running and would not expect to predict that behaviour. There is no way that counters the model. It is the sort of variability one would hope that the long runs of the models would show and I suspect that the models do not quite have enough of that sort of variability in general, which means that climate can change faster in one spell and less fast in another spell. They are probably slightly too uniform in their behaviours. There was no attempt and, in fact, there would have been no ability to predict the hiatus at that time. That was a decadal prediction problem for which the initial data were not available, but perhaps I can hand over to you.

That is a diplomatic answer. “The models were not in the position” and “there would have been no ability to predict the hiatus at that time”, as if they are now. And “suspect that the models do not quite have enough of that sort of variability in general”, wouldn’t be easier to say they still don’t.

[Dr Stott]
Maybe it is just worth pointing out that back in the Second Assessment Report there was a statement when it was talking about warming rates to 2100. The actual annual to decadal changes would include considerable natural variability, and this is part of what we are seeing at the moment and part of what has been assessed. Of course, it has been relatively challenging to assess this, because we are talking about very up-to-date information and therefore, for the cut-off date that the IPCC had, which was 15 March last year, there has not been a huge amount of literature, but that literature was assessed. In fact, the assessment that was made in the Fifth Assessment Report has been borne out by further evidence we have had since.

In the assessment it talks about particularly the contribution from internal variability, including a possible redistribution of heat within the ocean, and we have seen some literature since then-we also discussed this in the series of notes that the Met Office produced as well-that has talked about the potential role of the Pacific decadal oscillation, all within a context where we have seen multiple indicators of climate change, including estimates of the increasing energy of the climate system, continuing to increase in the last 15 years. There is more work to do to further delve into exactly the details of that Pacific decadal oscillation and what that is doing, but there is clearly an implication behind that, which is that there is an expectation for warming rates to pick up in the future as the mode of that variability switches into the other mode.

[Professor Sir Brian Hoskins]
At a meeting in Downing Street in the late 1980s I said that we could easily have a decade that would be cooler than the previous one and that would not mean the whole global warming thing had gone away. It is not unexpected, given natural variability, to get a behaviour like this but there was no attempt to predict it.

Basically it is said to be natural variability. But that was not the question. Even when we believe that it is natural variability, doesn’t that add to less confidence if it is not understood? What does the standstill actually mean in terms of their understanding? They avoided talking about the standstill in global temperatures. They just assumed it was a natural process that can’t be ruled out. I agree that a period of non-warming can’t be ruled out in a warming world, but what does this mean for the theory? It was brought into the discussion by Peter Lilley and also by Robert Smith, but all the alarmists witnesses kept well away from answering the question.

To me this is the big question: if human influence on cooling is less and the total anthropogenic effect is towards warming and there is a standstill in temperatures while there is “unprecedented” amounts of CO2 spewed in the atmosphere and that CO2 being the main cause of global warming, what does this tells us about the theory? That there are unexplained forcings/feedbacks that are not taken into account yet. What if those unknown effects have a big influence on global temperature? To me, just as to Smith, Lilley and Stringer, this looks as there should be less confidence, because some elements in the system are not yet known, not yet quantified and they seem to have quite some influence.

Increased confidence in anthropogenic warming

morecertain

After the release of AR5 SPM end of September last year, I was really surprised that the IPCC declared even more confidence in the human influence on climate, despite indications of the contrary. I was puzzled about this contradiction. To my joy I found that in the UK parliamentary Inquiry of Energy and Climate Change Committee into “the science” of UNIPCC AR5 there was some discussion about it. Indeed, when looking at the video I noticed this gem of a question (my own transcript of the video):

[Sir Robert Smith MP]
Is it possible, in the time we got, to summarize why there was an increased confidence in the human influence?

That was the puzzling question that was buggering me for so long. Peter Stott of the Met Office took the word:

[Peter Stott]
We have more evidence across the climate system. And we have evidence in terms of the ocean warming in particular. We understand we have better observations now, we understand not only the changes, but also the variability in ocean temperatures. Of course, if we going to measure temperatures below the surface of the oceans we have to send buoys down to measure those temperatures and so on.

[Sir Robert Smith MP]
Isn’t that more confirming the outcome warming. How does it increase the confidence that the human activity was the cause?

[Peter Stott]
It is providing our, it is increasing our level of conf [interrupted] I am sorry, excuse me,

[Sir Robert Smith MP]
I want to pin down, that is more a symptom of the system warming, but does it increase the confidence that the human activity was the cause?

That was my opinion also. He was talking about warming in general, not about why he thinks there is now more confidence in human influence. Good that Smith noticed it quickly and intervened. Stott continued:

[Peter Stott]
What we are seeking to do is to quantify the overall role of human activity. I mean, our null hypothesis starting point is explaining by internal natural processes and we can rule that out with high confidence levels. Then it comes to the question of the so called attribution question of how we quantify the human role, and that is what we discussed, the starting point could be that it is dominated by natural factors and human factor is rather small. So this is why we have increased our confidence in saying that extremely likely, more than half the observed warming, therefor the dominant cause is human influence. And to do that you need to bring all the evidence to bearing including importantly the ocean temperatures. Previously in AR5 there was a lot of variability, apparently, in the observational record, which we now understood was an artifact of different biases of those measurements. So, that is one example on which we have improved our confidence. But it is not an in terms of ocean temperatures but also in other factors such as the retreating ice and snow. We developed our understanding of the water cycle. We developed an understanding of extremes. When you look into our chapter, chapter 10, you will see we have a table in the back there of 33 rows where we itemized all the evidence, both the evidence, well, we have multiple lines of evidence, and also were we also have remaining uncertainties. And we have a greater wealth of evidence now than we had. With better understanding. With more observations. And also with the improved models as well.

He had a real problem keeping with the question and explained the warming as such. Even after the intervention of Smith the answer stayed really vague and in some places even circular. How disappointing for a lead author and the “Attribution Expert” of the Met Office. What I take from it is “we have more data now”. Indeed, 6 years of data extra. For the ocean temperatures this means 9 years of data in stead of 3. Still not very impressive. This is even less than the standstill of global temperature data and in climate terms insignificant. Not really impressive.

Myles Allen came to the rescue to clarify the matter and came in a real juicy discussion with Peter Lilley and Robert Smith.

[Myles Allen]
Just briefly to come back to the earlier conversation. I recall one of the big arguments in AR4 was over whether human influence via aerosols could be masking the human influences due to greenhouse gases. That was one of the big uncertainties. Now the uncertainties came down, because we are more confident that the aerosol forcing is not at the really high end that was considered possible back in AR4. And that increases our confidence in the size of the total anthropogenic warming over the past 50 years. Because our confidence about anthropogenic cooling [interrupted]

[Peter Lilley MP]
It means it is less?

[Myles Allen]
No, because aerosols cause cooling, because less aerosols and the total anthropogenic warming [interrupted]

[Peter Lilley MP]
There has been less cooling

[Myles Allen]
The total anthropogenic warming … if you are saying you are more confident about the anthropogenic cooling is less, then obviously the total anthropogenic warming is, … then your lower band of total anthropogenic warming goes up. We are more confident that humans are not cooling the climate, therefor we can have greater confidence that the overall effect, including all the warming factors, is towards warming. That’s just one of the factors that play in.

[Peter Lilley MP]
Let’s look at the real world, you know how much warming there has been, it is not how much warming there is in the models. There has been, let’s say 0.7 degrees warming. If that is not the result of 1 degree warming through CO2 and 0.3 degrees cooling through aerosols, which for example we know there is cooling through aerosols, than the amount of warming through CO2 must be quite subtle.

[Myles Allen]
The statement is about the total human induced warming. We have greater confidence in what the total human induced warming is than what we been able to give in AR4, That is an example of an increased confidence, resulting [interrupted]

[Peter Lilley MP]
Increased confidence and a smaller amount.

[Myles Allen]
Actually, no, I don’t believe that is a correct representation of the conclusions. But the key thing is that by ruling out something that might be compensating for the warming effect, by assigning a lower probability that what might be compensating for the the warming effect of CO2, you can increase your confidence that the overall human influence on climate is towards warming.

[Sir Robert Smith MP]
You are talking about the net effect of human activity.

[Myles Allen]
Yes, and that is what the statement is

[Sir Robert Smith MP]
But Mr. Lilley was making the statement that if there is less human input to cooling, then the human input to warming

Very good persistent questions of both MP’s. But they got this nonsensical answer, not even close to a clarification of what they have been asking:

[Myles Allen]
This uncertainty in aerosols is reflected in our uncertainties, specifically the warming attributed due to greenhouse gases. Which is highly relevant to quantifying uncertainty in the future. And as I emphasized before, it is that uncertainty which contributes substantially to the range of uncertainty in future projections. It is this balance between aerosol induced cooling and greenhouse induced warming. But this is specifically focusing on how much warming of the past 50 years is attributed to overall human influence. And that is the situation where our reduced estimates actually help increase our confidence in the total human influence.

Then the chairman interrupted the discussion and put the conversation on the rails of the consensus (well, due to this “higher confidence”). Saved by the bell.

Initially I couldn’t really grasp what he was talking about. But suddenly it dawned on me. It is really simple actually. It took me a while, but I think both Robert Smith and Peter Lilley saw it on the spot and were pushing for the answer.

This is how I think it makes perfectly sense. In the IPCC universe there are two main elements in the temperatures: natural variability and anthropogenic influences. The latter consist of aerosols (which have a cooling effect) and greenhouse gases (which have a warming effect). They assume that the greenhouse effect will be increasing, because our emissions also increase. Now the statement was not about the amount of anthropogenic warming, but about the proportion of warming in the anthropogenic influences.

Big difference.

When being more certain that anthropogenic aerosols have a lower cooling effect, this means that the net anthropogenic forces are now mainly in the warming area. In a way this is indeed an “improvement” over AR4 were the influences of aerosols was less certain. This could explain the change in terminology in AR5 (95% certainty about total human influences) to AR4 (90% certainty about human influences by greenhouse gases alone). This throws another light over the triumphal message that there was more confidence of human attribution in AR5 than in AR4. Did they really wanted to communicate such a meaningless message?

It is not hard to understand that Smith and the other MP’s understood it differently when asking this question. As policy makers they want to know about the certainty of the amount of warming caused by humans, while the scientists were talking about certainty about the proportion of warming within the anthropogenic influences.