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.

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