February 01, 2007
IPCC on Hurricanes
Posted to Author: Pielke Jr., R. | Climate Change | Disasters | Science + Politics
The IPCC Summary for Policy Makers is not out yet, but if this report in the Washington Post is in fact true, then we are in store for some controversy:
Global warming has made stronger hurricanes, including those in the Atlantic such as Katrina, an authoritative panel on climate change has concluded for the first time, participants in the deliberations said Thursday.
This will be controversial for several reasons. First, the WMO consensus was written by a range of scientists, including Kerry Emanuel and Greg Holland, who have argued that there is a strong global warming signal, but who have also accepted that their colleagues have valid arguments as well. Second, the IPCC cannot consider recent studies since it has a publication deadline (exactly what that is I don’t know but it was spring-ish 2006). Thus, the IPCC is a bit like a time machine telling us what the literature said about a year ago. The WMO statement incorporates more recent literature. However the IPCC is being presented as new. Third, the IPCC’s lead man on hurricanes and climate change is a fervent partisan in the debate itself. Whether his views are correct or not, it does not help the legitimacy of the process to see a carefully constructed consensus statement among 120 scientists with diverse views overturned by a very (very) narrow set of participants that may be only a few people.
This issue no doubt will become even more politicized than before, with partisans on both sides rejoicing or attacking. For my part, the IPCC overturns the WMO statement with some considerable risk to its own credibility. Of course, we’ll have to wait until May to actually find out the basis for this rejection.
would you object to that statement if it were categorized as "more likely than not true"? in other words, a 51% probability. that seems like a reasonable statement given that level of certainty.
Posted by: Andrew Dessler at February 1, 2007 08:52 AM
Roger, the explanation for all this is simple. First, you have misrepresented the WMO statement by cherry picking two sentences. Second, Kerry Emanuel's and Greg Holland's position on this issue are well known through their published papers, recent AGU presentations, and numerous media interviews. Third, a consensus statement by a relatively small segment of the relevant community is very different from a full blown assessment. The IPCC assessment evaluates the published literature. For example, the statement in the WMO consensus on the discrepancy between the Webster et al. observations and theory and modelling being a factor of 5 to 8 is not published anywhere and is simply incorrect (the only published analysis of this is my BAMS article, which states that there is a discrepancy "approximately a factor of two", and my subsequent analysis posted previously on Prometheus, the tropical listserv and most recently realclimate indicates a factor of 2-3, although the Webster et al. observations are within 20% of the expected increase according to Holland's version of potential intensity.)
Two lessons: Consensus statements should not be confused with full blown assessments, even if they include references and alot of signatures. The second lesson is not to provoke trouble and controversy by prematurely reporting the contents of the IPCC assessment (business as usual for a journalist, but I would hope that scientists would hold off on commenting on this until the IPCC actually releases its statement). Based upon what I know, the wording of the statement regarding hurricanes and global warming was not finalized as of last nite (which was presumably when the washington post article was written).
Posted by: Judith Curry at February 1, 2007 09:09 AM
Roger: I have grown quite skeptical of the "press leaks" that have come out of the AR4. Many (all?) of them have turned out to be wrong. I say lets see what the report says then we bash it.
Posted by: John Cross at February 1, 2007 09:09 AM
If that were the wording then the honest statement would be "we don't know yet". However, whatever the statement is, it's getting interpreted by the media at least, as
"PARIS - Global warming has made stronger hurricanes, including those in the Atlantic such as Katrina, an authoritative panel on climate change has concluded for the first time, participants in the deliberations said Thursday. "
Not a 51% chance, but a 100% chance.
Posted by: Dean at February 1, 2007 09:18 AM
You completely miss why this is important. The IPCC exists not to "pick winners" but to reflect the community consensus (as AW has written). Unless you are willing to reject the WMO statement as illegitimate, it cannot be simply dismissed as scientifically unacceptable.
There is not consensus on this subject. For the IPCC to suggest there is, is in fact misleading and wrong.
Andrew- I'd object just as strongly with the opposite wording. My beef is not with the content of the statement but its presentation as representing the consensus, which it is not.
Bottom line is that competing consensus statements imply there is no consensus. The IPCC takes sides at its peril.
Posted by: Roger Pielke, Jr. at February 1, 2007 09:35 AM
Dean is exactly right--both the WMO and (according to this report) the IPCC are saying there's lots of uncertainty on this issue. And yet the two statements (again, if the latest report is correct) will now be pitted against each other. How much difference, expressed as a percent chance that the conclusion is true, is there between "more likely than not" (the IPCC, allegedly) and "evidence both for and against" (the WMO)?
Posted by: Chris Mooney at February 1, 2007 09:52 AM
With regard to Judy's "lesson 2", why is that any sort of valid lesson?
If a contents of a document are leaked, and the leaked contents are reported in a newspaper, why shouldn't people comment on the contents of the leaked document? If they can't comment, should they also stop reading the article the moment the notice it's a leak? Both positions would be silly. Moreover, suggesting that scientists should withold comments on leaks -- has nothing whatsoever to do with science! That's a purely political position.
In any case, Roger's post made it clear the information was a leak and said "If this is true.... then...."
If the IPCC or anyone on the IPCC doesn't want the public to read leaks, or comment on leaks, or if the IPCC doesn't want to to develop a reputation for leaking, the IPCC should plug their leaks.
Posted by: margo at February 1, 2007 09:53 AM
I concur with John Cross. Most media leaks on 4AR shuold be tacken with a large pinch of salt. Many of them will turn out to be wrong. The IPCC would risk ridicule and self-destruction if it were to go against the consensus of professional bodies such as the WMO.
I guess what we are witnessing is something else: the collusion of climate scientists and campaign journalists in an attempt to put maximum media pressure on the ongoing talk and negotiations in Paris. After all, AP was also responsible for the promotion of grievances by a handful of discontented people who complained that the 4AR draft on sea level rise was not catastrophic enough and the whole report rather like a “sugarcoated version” of reality.
Posted by: Benny Peiser at February 1, 2007 10:31 AM
The IPCC characterizes "about as likely as not" to indicate that the certainty is 33-66%. So "more likely than not" is >66% certainty.
The WMO "evidence for and against" might be interpreted as 50-50, but perhaps the IPCC's language is more precise 33-66%. Clearly, the WMO did not take a side in the discussion, so if accurately reported, this does represent a difference in view.
From a journalistic standpoint the IPCC is in a no win situation. If the report by the AP was in error then the IPCC will be seen as backing off. If the AP is correct, then the IPCC has misrepresented the state of scientific opinion.
Posted by: Roger Pielke, Jr. at February 1, 2007 01:00 PM
Roger, you are the one that has framed this issue as a winner/loser issue (and the media is picking up on this unfortunately).
There are numerous distinctions between a consensus statement (such as the WMO statement) and an assessment report (such as that conducted by the IPCC and NRC/NAS assessments).
In an assessment, great care is taken to select contributors representing multiple points of view and in the case of the IPCC representatives from many countries. The group of 10 scientists on the WMO committee would not pass a bias test, with numerous members having the same Ph.D. advisor and several members from the same institution.
In an assessment, great care is taken to substantiate all statements reporting results or analyses with references to the refereed literature. For example, the statement in the WMO report "by a factor of 5 to 8" would not have made it through the scrutiny of an assessment. While such an analysis is arguably suitable for an assessment, substantial documentation on how the analysis was done would be needed. While I have not specifically made the comparison for Emanuel's analysis, I don't see how it would differ from my analysis of a factor of 2-3 for Webster et al. study (which was posted here previously) since Emanuel used the same data as Webster. The extensive external review that the assessment reports undergo would filter out any technical errors in an analysis.
Conclusions in assessment reports are crafted very carefully. A statement like "for which we can provide no definitive conclusion" in the WMO report is not a statement that would appear in a scientific assessment. Science is not about providing definitive conclusions. Assessments attempt to report the uncertainty of the scientific research, using words like
That said, I think there was much value in the exercise of putting together the WMO statement, it served the very useful purpose of staking out a more defensible scientific position on this subject (than what has been portrayed in scientific meetings and the media by many members of this community) and getting buy in for this buy the broader community of TC forecasters and researchers. It is my understanding that this is why Holland and Emanuel participated in this, although neither would have written the statement in exactly this way.
But consensus statements are not assessments, and should not be used in the way that assessments are used to inform policy makers. Whether the assessment by the IPCC of the TC-global warming issue is sufficient, I can't say (i haven't read it). I have called numerous times including in my testimony for a proper assessment of this issue by the NRC (U.S. National Academy of Science, which frequently includes international scientists).
We will all be waiting for the final IPCC Statement for Policy Makers (the Washington Post article was really premature).
Posted by: Judith Curry at February 1, 2007 02:02 PM
I am starting to wonder whether we may be witnessing the birth pangs of a new brand of climate scepticism. How else can one interpret the increasingly discordant criticism on the IPCC by people who appear to feel no longer represented by "the scientific consensus?"
If the upshot of tomorrow's IPPC report leads to the eventual split between climate realists and climate alarmists, I would consider such a development as rather positive. It would certain help to clear the air.
Seas rising faster than U.N. predicts: study
PARIS (Reuters) - Sea levels are rising faster than predicted amid global warming, a group of scientists said on Thursday in a challenge to the U.N.'s climate panel which is set to issue a report toning down the threat of rising oceans.
The researchers -- from the United States, Germany, France, Australia and Britain -- wrote in the journal Science that seas have been edging up more rapidly since 1990 than at any time in more than a century, outpacing computer projections....
Posted by: Benny Peiser at February 1, 2007 02:49 PM
You claim that IPCC does not represent a consensus is absolutely incorrect. From the IPCC:
"In taking decisions, and approving, adopting and accepting reports, the Panel, its Working
Posted by: Roger Pielke, Jr. at February 1, 2007 02:50 PM
It's been said before, but no-one seems to be paying attention: This story is based on a second-hand report. Why not wait a few hours and see what the bloody thing actually says?
Posted by: Mark Hadfield at February 1, 2007 03:09 PM
Roger and all,
I generally stay out of blogs, but as a member of the US delegation here I would strongly counsel against premature judgment. Once the final document is out, I hope that you and others will fairly compare what the final report says with the WMO consensus statement. I suspect that an objective analyst who carefully reads both the IPCC and WMO documents - that is, does not cherry pick - will find far more common ground than might now be anticipated.
The two reports are not identical of course, nor should they be, but in the end the careful reader will see far more areas of agreement than current reports might suggest. For those who are relying on press reports or any earlier drafts of the IPCC SPM, you will simply be misled.
In short, wait for the report, look carefully at what it says, and then evaluate and critique. This would be the fair process.
See you back in Boulder,
P.S.: A little after midnight here in Paris, still at UNESCO, but the final draft has been approved. Just waiting for one final review to ensure all agreed upon changes have been made.
Posted by: Randy Dole at February 1, 2007 04:11 PM
Roger, your dismissal of Judith's contribution is incorrect in its absoluteness. (I would say it was "absolutely incorrect", but I avoid phrases like that.)
Judith pointed out some differences between the process that produces "consensus" statements like the WMO statement that we're discussing and the process that produces "assessment" reports like the IPCC AR series. It would not be surprising if the different processes produced slightly different results, nor would it be evidence of bias or dysfunction in either one.
You found the word "consensus" in an IPCC policy and on that basis said that Judith's "claim that IPCC does not represent a consensus" (which she never actually made in those words) is incorrect.
The excerpt you quote refers to consensus *within* the Working Groups and Task Forces. As assessment involves experts in the field reviewing the evidence and coming to an agreement (a consensus) amongst themselves about what that evidence means. In a settled field, one would expect the result to match the general consensus in the scientific community (two very ill-defined concepts in one sentence). In a developing field, maybe not.
Posted by: Mark Hadfield at February 1, 2007 07:09 PM
Mark- Thanks much for your comments.
We may have to simply agree to disagree on this one. The WMO and IPCC processes in this case are very much similar. The WMO lacked the benefit (ahem) of political stakeholders in the room while the texts were being negotiated, but it did involve a multi-country line-by-line negotiation.
You assertion that the IPCC assessment may not reflect the general consensus of the broader scientific community flies in the face of how the IPCC represents itself and it is generally invoked. See Andrew Dessler's arguments on assessments, for instance.
Posted by: Roger Pielke, Jr. at February 1, 2007 09:41 PM
Roger: Intent to try to achieve consensus isn't identical to consensus.
Benny: Dream on.
Posted by: Steve Bloom at February 1, 2007 09:42 PM
You are correct that the intent to achieve consensus isn't identical to consensus. When one tries to achieve consensus and fails, that means there is no consensus. "No consensus" is the default.
Roger says the climate community has achieved no consensus that AGW has already caused increases in hurricanes. The WMO concluded there is no such consensus. It's clear members of the climate community are arguing vigorously about this right now at blogs, AMS meetings, in peer reviewed journals and in newpapers interviews.
It's abundantly clear there is no consensus on this point.
Were the IPCC members to get together and collectively agree that the climate research community agrees that AGW has already resulted in increasing hurricane severity or numbers, the IPCC claim that there is a consensus on this point would be laughably incorrect.
Posted by: margo at February 2, 2007 06:47 AM