[Grizzly]

I'm clever, yes, but that is irrelevant. "expert judgement" is just institutenglish for subjective assessment from the part of the IPCC.

What is so subjective about these assessments?

(And regardless of that whole discussion, the subjective assessment of an enormous group of climatologists still carries a lot more weigth then some random internet dude).

[Phantom Hoover]

I'm clever, yes, but that is irrelevant. "expert judgement" is just institutenglish for subjective assessment from the part of the IPCC.

Or maybe it means that it's the judgement of people who have spent years dedicating their lives to studying and understanding the climate. As opposed to, say, an architect.

[karajorma]

And he also basically said that he will never ever change his mind, no matter what, as an answer to the question about "what" would change his mind. He pu**yfooted around the issue a bit and quickly passed the question over to Nye without giving a direct answer, but do rewatch it, that is what his answer boils down to: "I am right because of what I believe and everybody else is wrong ... and f*** all the evidence to the contrary."

Sadly that is the point of view of most YECs. Which is ****ing hilarious given how often they complain about scientists not being willing to listen to a dissenting opinion. 

[watsisname]

Qualitative assessment is necessary because often there is no clear way to define a metric for the confidence level that a result is correct.  Consider the question 'Are human activities a significant contributor to current climate change?'.  It's not like we can say 'we changed the composition of the atmosphere in this way X number of times, keeping all else the same, and we observed warming N% of the time'.

What we can do is model the climate system with and without the anthropic forcing, doing some statistical analysis of how many models show a response from the anthropic forcing and how significant that response is.  Of course, we should not simply judge confidence by model output, we should also review the knowledge upon which these models are based.  How well do radiative-convective models portray the physics?  How well do we understand the radiative forcings, natural and anthropogenic?  How good are our constraints on the roles of internal variability and feedback effects?

There is no way to quantitatively assess these things together to arrive at a level of confidence in our finding.  Instead confidence is based on expert judgement of the robustness of evidence and our understanding of the processes and underlying physics.

[Luis Dias]

That's all well and fine, and I agree with the need for qualitative assessments. I think it's hilarious they need to glue a "95%" number on it, as it tries to capture a quantitative measure of a qualitative subjective assessment. It's also contradictory to the fact that they have reached some consensus that some particular dangers pointed out in AR4 were overblown (like extreme weather phenomena, etc.) and the empirical assessment that the models are clearly running hotter than reality. In the overall scheme of things, however, this is almost peanuts. Overall, I accept the IPCC's findings as much as I would accept any other political bodied scientific report. It has a load of ideological shenanigans but it also has a good chunk of data and analysis that is well needed if we are to make decisions over that issue.

The bringing climatology over this discussion was, I think, due to the ease of which some scientific challenges to mainstream consensus theories get bogged down and marked as the word of some heretic, an "evil-doer" that is in the payroll of some evil corporation doing evil nasty things like spreading lies and confusions and what nots. The conversation gets polarized and some nuances or other small snippets of skepticism here and there are gargantually hyped as evidence that we are in the presence of someone we should get pitchforked. This usually makes for bad conversation and that was the only thing being pointed out, as far as I see. In the wider internet, I clearly see the victims and destruction of this polarization, with journalists and bloggers fighting endlessly against the evil on the other side, all claiming scientific and moral superiority over the others, stepping and effectively destroying any sensible and rational, calm and nuanced discussion we could possibly ever have.

[Grizzly]

What exactly do you mean with "Politically bodied"? Is it because it's part of the UN?

[Luis Dias]

It's filled with politics from its inception, to its purpose and thorough its process. Conclusions are vetted and only written down if the most important countries accept it. This both goes towards a more hardline assessment in some particular cases, or towards its watering down for others.

[The E]

The problem being that the findings of this report are coloured by what the politicians want to hear, and do not represent a complete scientific consensus on the topic (Which is another example for why Science should not be open to public, political debate).

[Grizzly]

It's filled with politics from its inception, to its purpose and thorough its process. Conclusions are vetted and only written down if the most important countries accept it. This both goes towards a more hardline assessment in some particular cases, or towards its watering down for others.

This seems weird. I have talked to some climatologists who teach at our university (who now face getting fired because the university is stupid) who often feel that not enough has been done, or is being done. Considering how often the IPCCs report are played down or outright scandalized during political discussions, and considering that "climate summits" don't achieve anything except that one country tries to limmit economic growth of another country whilst negating any sort of responsibility themselves. I think that if those "most important" countries actually had a say, they would have just shut the entire operation down.

Considering how the IPCC works (Which mainly involves feeding a lot of data into a lot of models, and increasing the fidelity of those models and the data) I can not really see how politics are at play here (as it's mainly maths). I also perfectly see why there could be a quantative measure to it, as it's maths.

[Luis Dias]

You are confusing the IPCC process with the daily production of scientific papers. Those are not to be confused, they are wholly separate. The IPCC process is one of a giant report that tries to assess the available scientific papers over all the relevant issues, organizes a giant file of them and editorializes on all those issues. This is an international process that is overseen by the UN, and all countries can de facto decide to veto or not the final report. There were widely reported issues with China and Germany (for instance) before.

The fact that some people think "not enough was made", etc., has little to do with the IPCC. The political summits are political in nature and they are about deciding political action, not science. Regarding the harshness of the report, some think it wasn't dire enough (read, alarmist enough), some say it was more alarming than the evidence supported. It's always funny to me how people who are slightly more skeptical of the alarmist message we get constantly about the "nasty effects" of GW than the IPCC are considered to be in the wrong side of science denialism, while those who promote radicalism and alarmism that is unjustified by the very wording of the IPCC reports are somehow on the "right side".

This points to an obvious ideological bias in the mediatic reasoning. It's something just profoundly human and personally, I just "sigh" at it and let it slide. I hope the alarmists are wrong, but I also think we should have some kind of technological and political process able to curb the potential dangers ahead.

[MP-Ryan]

This matter will never be settled in debate. It's already been settled with basic empirical evidence - but a debate is not about evidence, nor about finding common ground (there isn't any here, since one party is objectively wrong). A debate's about scoring points and building a narrative.

The audience rarely benefits because debates are not effective heuristics to select empirically supported truth. Instead, debates reward tactics more than substance. As a national-ranked debater in high school - I ended up doing such a good job as Turkey in one simulation they sent me to the Turkish embassy in DC for a dinner, I'm an international hero and I get all the ladies - I worked pretty much every conceivable geopolitical topic from every available angle. It didn't really matter what the truth was, or how much evidence we had in either camp: you could persuade an audience of your case with the same tricks no matter the substance of your argument.

Scientists in general are often unsuited for debate because science encourages constant qualification and parametrization and often answers questions with 'we don't know yet' (rarely, if ever, in this topic, but often in others). These are awful things to do in a debate, because human authority heuristics punish uncertainty and reward confidence.

Karajorma's quantum physics metaphor is apt. If you put a quantum physicist up there to debate the existence of elementary particles with an Aristotelian philosopher, the quantum physicist will get shredded. His complex structures are counterintuitive and obscure, and they require enormous background to understand. The philosopher's positions are tangible and clear and he's able to focus on offense rather than simplifying a complex topic.

Of course, the analogy breaks down in the complexity - it takes no more than an elementary school education to understand who's right in this debate.

e: Put more simply, in InsaneBaron's terms: debates cannot work for the best interest of both parties (or the audience) because debates are not an effective means to select between theories. They are an effective way to select between debaters on the basis of human pyschology.

Late to the party, but oh so much this.

I've long since come to the opinion that it is simply not worth the effort trying to logically explain how creationist beliefs are empirically wrong and disprovable to someone who holds them deeply.  Explaining evolution to people who are confused about it is a worthy endeavour; trying to disabuse people of their entrenched religious notions is not.

When it comes to teaching in school, we lobby that public school remains secular in funding and curriculum; we ensure that no religion gains precedence in public education, and we use constitutional arguments to do it.  And if the religious crowd would like to run their own school system and teach religious education in addition to the approved curriculum there - fine.  They can pay for it.

[Mars]

Charter schools - we pay for it, they can teach whatever they want.