Tuesday, October 02, 2007

No climate "consensus" within the IPCC

If you're still under the impression that recent IPCC reports represent a clear "climate consensus" by thousands of scientists, you really should spend some time reading the IPCC comment documents available here.

I've spent a short time reading the comments, and it's been very interesting to get a better look at how the IPCC works internally. It's clear that IPCC reviewers provided plenty of specific opposition to the alleged climate consensus.

Here's one comment from this link:
There is no scientific merit to be found in the Executive Summary. The presentation sounds like something put together by Greenpeace activists and their legal department. The points being made are made arbitrarily with legal sounding caveats without having established any foundation or basis in fact. The Executive Summary seems to be a political statement that is only designed to annoy greenhouse skeptics. Wasn't the IPCC Assessment Report intended to be a scientific document that would merit solid backing from the climate science community - instead of forcing many climate scientists into having to agree with greenhouse skeptic criticisms that this is indeed a report with a clear and obvious political agenda. Attribution can not happen until understanding has been clearly demonstrated. Once the facts of climate change have been established and understood, attribution will become self-evident to all. The Executive Summary as it stands is beyond redemption and should simply be deleted.
[Andrew Lacis]
Some background on Andrew Lacis is here.

A related excerpt from this link:
In “Peer Review? What Peer Review?” McLean writes, “The IPCC would have us believe that its reports are diligently reviewed by many hundreds of scientists and that these reviewers endorse the contents of the report. Analyses of reviewer comments show a very different and disturbing story.”

In Chapter 9, the key science chapter, the IPCC concludes that "it is very highly likely that greenhouse gas forcing has been the dominant cause of the observed global warming over the last 50 years". The IPCC leads us to believe that this statement is very much supported by the majority of reviewers. The reality is that there is surprisingly little explicit support for this key notion. Among the 23 independent reviewers just 4 explicitly endorsed the chapter with its hypothesis, and one other endorsed only a specific section.

Moreover, only 62 of the IPCC’s 308 reviewers commented on this chapter at all. As with other chapters, simple corrections, requests for clarifications or refinements to the text which did not challenge the IPCC’s conclusions are generally treated favourably, but comments which dispute the IPCC’s claims or their certainty are treated with far less indulgence.
It appears that the IPCC review comments were only placed online after some "Freedom of Information"-type pressure was applied. Some background is here and here.

6 comments:

Anonymous said...

I haven't read all the comments, but have read several hundred of them. The overall impression that I gain is that the majority have issues with the style of writing rather than the science itself. Where there are quibbles, these are minor and the overwhelming impression I gain is that there is a surprising degree of concensus, given the number of people reviewing the work.
There are of course a small number of exceptions , one of which you have pulled out, but you have to dig pretty deep to find these and I feel you are painting a false picture of the extent to which there is lack of consensus.

Importantly also, of the comments I read, there were actually more suggesting that the IPCC underestimates impacts than over-estimates them!

Ilya Maclean

Tom said...

Hi Ilya,

Did you thoroughly check out both comment documents on the key chapter (chapter 9; Understanding and Attributing Climate Change)?

I did. I saw plenty of specific, vociferous opposition to the alleged consensus. (I don't know what you could mean by having to "dig deep"; to me, all comments seem about equally easy to read).

Tom

Anonymous said...

Actually this question has been addressed scientifically here:

As N. Oreskes points out in Science, 100% of relevant papers support the consensus view that a significant fraction of recent climate change is due to human activities.

Ilya

Tom said...

Hi Ilya,

1. That Oreskes study has been thoroughly discredited here .

Two excerpts:
---
These objections were put to Oreskes by science writer David Appell. On 15 December 2004, she admitted that there was indeed a serious mistake in her Science essay. According to Oreskes, her study was not based on the keywords "climate change," but on "global climate change" (3).

Her use of three keywords instead of two reduced the list of peer reviewed publications by one order of magnitude (on the UK's ISI databank the keyword search "global climate change" comes up with 1247 documents). Since the results looked questionable, I decided to replicate the Oreskes study.
...
The results of my analysis contradict Oreskes' findings and essentially falsify her study:

Of all 1117 abstracts, only 13 (or 1%) explicitly endorse the 'consensus view'.
---
2. Have you thoroughly checked out the comment documents for Chapter 9 (above) yet? If so, do you see any sign of "100%" scientific consensus on catastrophic AGW?

Anonymous said...

"Of all 1117 abstracts, only 13 (or 1%) explicitly endorse the 'consensus view'"

Point taken regarding Oreskes's study. I wasn't aware of this.

Regarding "Of all 1117 abstracts, only 13 (or 1%) explicitly endorse the 'consensus view'" - this is a meaningless statistic as it does not state how many studies testing the consensus view hypothesis. One would expect most studies with "global climate change" to be addressing other aspects of climate change.

Peiser lists only two which discredit consensus. One is published in the Bulletin of the American Association of Petroleum Geologists and reviews the opinions of their members (obvious conflict of interest!) and the other is 15 years old (and sites inadequate computer technology as amongst the main reasons for uncertainties).

I haven't read the Chapter 9 comments but will do so in due course.

Ilya

Tom said...

this is a meaningless statistic as it does not state how many studies testing the consensus view hypothesis. One would expect most studies with "global climate change" to be addressing other aspects of climate change.

Ok. But you are not actually arguing that Peiser's "1%" is meaningless while simultaneously arguing that Oreske's (or Gore's) "100%" is meaningful, are you?