I don't see how it differs from what I am saying.

Prof Ron Prinn was pointing to all the factors in the model that has to be considered. He certainly doesn't "question" the policies that will reduce aerosol emission in a way that implies he is against a reduction. He is stating that there are many complex feedback factors that need to be addressed in the model.

But hey, I too recommend people watch it for themselves.

The dangers of global dimming show there is a clear need to reduce aerosol emission and that will result in an increase in temperature, which is another reason we need to do more in reducing CO2.

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Originally posted by What's in your mind:

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Since you are a fan of Prof Ron Prinn, will you be looking forward to reading the IPCC forth assessment in the knowledge that the concerns Ron Prinn have been addressed

I think you don't get the difference between objective confidence levels and subjective opinion, so I will leave it at this

Typical of you WIYM. You quote a scientist and misrepresent what they say, such as

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"Prof Ronald Prinn says it is 'arrogant' to try and predict climate change"

You then quote a 2001 paper which had already been addressed with a 2007 quote from Prinn.

So, then you find something else to pick at, anything, so long as you hack away to try and suggest there is some ludicrous reason for ignoring the likelihood of AGW.

Well Robbie, I assume you have read the IPCC summary report. Can you let me know what are the objective observations in the report and what are the subjective opinion of the authors?

The point of the webcast is to highlight the uncertainty of climate science and Ronald Prinn actually warns against the claims of other models that project high certainty. If you are not able to get this message, there is no point of yours watching the webcast.

The point of subjective opinion that is distinct from other observations that can expressed through objective confidence levels, pointed out by Ronald Prinn in the 2001 paper still holds for the present IPCC report but I guess it is beyond you to grasp this simple truth

WIYM, what exactly do you mean by "objective" and "subjective"? I don't think you are using them with their common meaning.

Yup, I am. It appears the dynamic duo of you and Robbie Write aren't

No really, I was asking for you to define what you mean so that I'm not confused about what you're saying.

For example, Dictionary.com provides several definitions of "subjective", one of which is "placing excessive emphasis on one's own moods, attitudes, opinions, etc.; unduly egocentric." which is what I would say is the common usage when applied to opinion.

I am surprised that as a scientist you had to rely on dictionary.com to come up with a definition of objective and subjective.

Observer independent and observer relative are the terms that I would use. I had already gone through this in the other thread 'IPCC confidence levels' so I have no desire to go through them again with you

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Originally posted by What's in your mind:
The point of the webcast is to highlight the uncertainty of climate science and Ronald Prinn actually warns against the claims of other models that project high certainty. If you are not able to get this message, there is no point of yours watching the webcast.

Yes, but he also shows that modeling is not only possible but vital and shows that the MIT model constrains the uncertainties and gives a range of probabilities that we can be certain of.

He makes it very clear that with no policy on climate change, then the range of probabilities tend towards a high rise in temperatures that he states "could be irreversible".

Whereas a policy to control CO2, would create a range of probabilities that tend to a lower rise in temperatures.

So you are definitely misrepresenting him by suggesting that he considers it arrogent to try and predict climate change.

You haven't acknowledged he is "delighted" with the incorporation of the range of probabilities in the IPCC 4th assessment, that was causing him concern before, instead you cited a 2001 paper, which referred to his previous concerns.

But, I say again, everybody who is interested, and would like to learn more about climate-change should watch the webcast for themselves.

I see you have not replied to me query about the objective observations and subjective opinion of the IPCC report. Do you have any idea?

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Originally posted by What's in your mind:
Observer independent and observer relative are the terms that I would use.

What exactly is observer-independent supposed to mean? Every conclusion is a human construct and therefore dependent on the observer. Scientists strive to be "objective" in that they try not to let emotional attachment or preconceived ideas sway their judgement. This is the meaning of "objective". Not some idea of science without the scientist.

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I had already gone through this in the other thread 'IPCC confidence levels' so I have no desire to go through them again with you

I think this explains why I couldn't understand your point.

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Originally posted by What's in your mind:
I see you have not replied to me query about the objective observations and subjective opinion of the IPCC report. Do you have any idea?

are you talking to me?

When you say "subjective opinion" are you referring to the "expert judgment", that Prof Ron Prinn was concerned about in 2001?

yes

To Mindcrime,

To understand the difference between observer independent and observer relative, you can read Searle's article on Social Ontology that came out in Anthropological Theory in 2006. To explain it to you, I think is beyond my capabilities

Fair enough but I think it's clear that you are using these words with a specific meaning that is not obvious to most of the people reading your comments.

To demand that a construct such as the IPCC report be observer-independent is, frankly, impossible.

Nope I think I am using it in the right sense in the context of 'expert judgment' and it is you who is using it in the wrong sense

There is some "Guidance Notes on Lead Authors of the IPCC 4th assessment report on addressing uncertainties".

http://www.ipcc.ch/activity/uncertaintyguidancenote.pdf

What is clear here is that where there are expert judgments made, there has to be "traceable accounts of the steps used to arrive at estimates of uncertainty or confidence"

There is a need to assign a level of confidence to the expert judgment.

The acknowledgment of expert judgments and its ability to effect the reliability of a predicition contributes to the range of possible outcomes.

So when the IPCC publish a range of possible outcomes, the expert judgments are factored in.

This is why Prof Ron Prinn is "delighted" with the IPCC's approach to uncertainties in the 4th assessment.

I can explain my expert judgement but that does not make my judgement objective and observer independent. Another expert can come to a very different conclusion and can also explain the rationality behind the decision.

Confidence levels on the other hand occurs out of scientific tests and the claims are observer independent. You can question the methodology and the data, but once you have accepted the methodology and data, the findings would not be subjective to personal interpretations.

Now does this makes sense?

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Originally posted by What's in your mind:
Nope I think I am using it in the right sense in the context of 'expert judgment' and it is you who is using it in the wrong sense

It's not a matter of right or wrong, it's a matter of how you communicate your ideas through an imperfect medium like a message board.

Perhaps a more concrete example will help. By your definition there is no such thing as an "objective opinion", it's an oxymoron, but in real life people will often ask for an objective opinion on something (i.e. one not tainted by attachment or emotion).

I suggest you brush up on your philosophy of science, espcially on the issue of being epistemically objective and epistemically subjective. As I suggested earlier Searle gives a very good explanation of this

Hey, if it's more important to you to "win" arguments than be understood then whatever - it's your loss.

I am happy to know where I am going wrong. Please let me know.

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Originally posted by What's in your mind:
he says there is a possibility of global temp being higher in the MWP

I finally got a few moments to watch some of the webcast (only the first 20 minutes) and you are right that it is fascinating stuff.

However, when talking about the temperature reconstructions he didn't mention the MWP at all. As I say, 1200 years ago explicitly rules out the period termed the mediaeval warm period which was only 1000 years ago. Does he mention it later on or have you got this wrong?

I am of course speaking from memory, but if I remember that it was in the fourth slide into the presentation, he talks about temperature reconstruction and he talks about hockey stick and how other reconstructions muddies the water. Then he says what he is confident about is the claim that the recent temperatures are the highest in the last 1200 years and not beyond it. If not MWP is there any other period in recent history that witnessed high temperature? As I understand there is a lot of confusion on the actual duration of MWP

I've seen that part and he doesn't mention the MWP at all. I'm pretty sure he isn't suggesting that there was a warmer period 1200 years ago but rather that reliable, well time-resolved data only goes back 1200 years so that is far as you can strongly defend. The only reconstructions that I have seen that cover the first few hundred years CE are the Mann & Jones reconstructions from a couple of years back which I think are probably not very solid. They indicate that the temperature was at or below the 800CE level.

Of course the problem is that reliable measures do not last for thousands of years (there aren't 2000 year-old trees that you can take tree rings from).