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February 14, 2007

Final Chapter, Hurricanes and IPCC, Book IV

Posted to Author: Pielke Jr., R. | Climate Change | Disasters

Two years ago NOAA's Chris Landsea resigned from participating in the IPCC citing concerns that the chapter on hurricanes had been politicized, specifically citing the role that Kevin Trenberth, IPCC convening lead author for the chapter that covered hurricanes, had playing in an October, 2004 media event hyping a hurricane-global warming connection.

With this post we'd like to follow up and in the process close the book on this particular dispute -- at least for us here at Prometheus. The "hurricane wars" are probably far from over, but we should acknowledge that both Chris Landsea and Kevin Trenberth both come out of this situation looking pretty good. Both can and should feel vindicated. Read on if you are interested in a few final details from the last chapter in this story.

The first signs that there might be a happy ending to this saga were evident in June, 2005 when Kevin Trenberth authored a commentary in Science in which he wrote:

[T]here is no sound theoretical basis for drawing any conclusions about how anthropogenic change affects hurricane numbers or tracks, and thus how many hit land.

This led me to conclude at the time:

Landsea and Trenberth are scientifically on the same page, and the perspectives now being espoused by Trenberth [in Science] are (in my interpretation) entirely consistent with what Landsea argued at the time he stepped down from the IPCC.

So it shouldn't have been too surprising when the IPCC accurately reported the state of scientific understandings of tropical cyclones and climate change in its recent summary for policy makers, despite some last-minute concerns. (Of course, the WMO Consensus Statement was probably the most significant factor shaping the IPCC's final judgments.) When the full IPCC WG I report comes out, I have no doubts there will be some room for quibbling about the details on this subject, but the big picture presented in the SPM appears to me to be just about right.

Yesterday in an online Q&A with the public organized by the Washington Post Kevin Trenberth addressed an explicit question about this issue:

Washington, D.C.: The National Oceanic and Atmospheric Administration's Chris Landsea resigned a year ago from the IPCC and leveled charges that the IPCC, and you in particular, had a overly-politicized view of global warming trends. (link to here: Specifically, I believe that Landsea objected to the fact that some on the IPCC would "utilize the media to push an unsupported agenda that recent hurricane activity has been due to global warming." I assume that you disagree with Mr. Landsea. Do you believe that recent hurricane patterns have been negatively affected by global warming?

Kevin Trenberth: This is what the IPCC says in the Policy Makers Summary: "There is observational evidence for an increase of intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures. There are also suggestions of increased intense tropical cyclone activity in some other regions where concerns over data quality are greater. Multi-decadal variability and the quality of the tropical cyclone records prior to routine satellite observations in about 1970 complicate the detection of long-term trends in tropical cyclone activity. There is no clear trend in the annual numbers of tropical cyclones. " This was agreed to by the US Govt and crafted by the lead authors present (including me). Landsea's comments were not correct.

Dr. Trenberth stuck to what the IPCC concluded and did not take the bait offered by this questioner. He was also taking the high ground in claiming that the IPCC SPM accurately reflected the current state of the science. But Chris Landsea should feel good as well because there can be no doubt that his actions helped to ensure that the IPCC got things right in the end.

Kudos to both, but it's time to move on.

Posted on February 14, 2007 03:56 PM


Good point, Roger. Chris Landsea does deserve a ton of credit. After all, the IPCC's multiple layers of peer review as well as the requirement of following the peer-reviewed literature could never have produced a reasonable report all by itself. No way.

On a similar note, I marched in a "Free Mandela" rally in 1987. I'm pretty sure that was what caused the fall of apartheid.


Posted by: Andrew Dessler [TypeKey Profile Page] at February 14, 2007 10:03 PM

I boycotted the last general election in the UK, so kudos to me for any good things that have happened since - and those still to occur :-)

Posted by: James Annan [TypeKey Profile Page] at February 14, 2007 10:59 PM

I don't see how this book can be closed without some statement from Landsea. Does he accept that the actual SPM is scientifically accurate or not? He didnt have any problems speaking out before, why is he so silent now?

Posted by: William Connolley at February 15, 2007 02:59 AM

Thanks for the update. It's good to see there is some concensus now. Although it seems the cost of this has been the complete absence of numbers which invites an assumption that the effect is much more worrying than the very small localised effects. Maybe the full report will flesh this out a bit.

It seems that Dr Trenberth has accepted that his positions imposes responsibilities. This is to be commended but will not undo what was said earlier.

The problem is, highly public statements like this can never be "recalled". Like the misleading hockey stick graph they do the tour of the world media, get passed on and become part of accepted common knowledge.

Posted by: hurricane harry at February 15, 2007 03:56 AM

Andrew- Do they feed angry/bitter pills to you bloggers over at Grist? Maybe try the decaf ... ;-)

James- Be careful announcing this fact, some of your fellow citizens may have wanted your vote, given Labour's, ahem, popularity;-)

William- I don't know Chris' views on the SPM, and as far as this post, not sure they matter. I'm sure we'll hear from him sometime.

Harry- Thanks. I am optimistic about the self-correcting nature of both science and policy.


Posted by: Roger Pielke, Jr. [TypeKey Profile Page] at February 15, 2007 06:28 AM

Roger, unless you`re saying that the IPCC got hurricanes wrong before, I hardly understand how Landsea`s departure helped to ensure a better result. He may have helped Trenberth stick closer to script, but that`s a differnt story, isn`t it?

HH, isn`t the problem that Trenberth at this point was simply unable to drag the consensus along with him at this point in time, though with further warming we expect him to be proven right?

Posted by: TokyoTom [TypeKey Profile Page] at February 15, 2007 08:11 AM

Tom- Thanks. Did Jim Hansen's public complaints about NASA 's communications policies contribute to improving that process?

An if there is any questions about whether the IPCC was at risk of getting it wrong on this issue, please read my posts of the week of Feb 2 and after, especially the IISD summary notes.


Posted by: Roger Pielke, Jr. [TypeKey Profile Page] at February 15, 2007 08:24 AM

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