In the middle of the hearing there was an exchange on sea level rise between Ralph Hall (R-TX), the committee chair, and Kerry Emanuel, a scientist at MIT who I have known for quite a while and for whom I have a lot of respect.
Hall prompted the exchange with these comments (quotes below are from this webcast):
About 5 minutes later when being questioned by another member, Emanuel took the opportunity to direct some comments back to Hall:HALL: Do you recollect when Dr. Holdren was here -- he’s the president’s science advisor --on the sea level rise? His testimony was that it would rise 12 feet. You know when the ice all falls and melts into the ocean. The proper person measured it, as you know the very next year the so-called gold standard of scientific consensus by global warming advocates projected that the oceans would rise by 7 and 23 inches. So that’s who’s advising the president and that’s the reason that we are in all the trouble we’re in right now.
Hall responded to Emanuel and they engaged in a short exchange:EMANUEL: Mr. Chairman, I think that you misquoted Dr. Holdren. He was referring to what would happen if all of Greenland’s ice disappeared. That is not projected to happen. But his numbers are correct, if it did we would see a sea level rise of about 22 feet. Unfortunately it is a risk. It’s way out there because we don’t understand the physics of ice, but I think that is what he is referring to.
HALL: In a recent hearing Dr. Holdren was sitting right there where you are there and he said that the Republicans needed to be educated on the issue. In an August 2006 interview with the BBC news he reportedly said that if the current pace of change continued catastrophic sea level rise of four meters – that’s 13 feet not 12 feet – I was wrong, was within the realm of possibility. While you were going with the interview I asked “how sure were you about your prediction”? And the hard cold facts were that the very next year the so-called gold standard of scientific consensus by global warming advocates projected that the oceans would rise between 7 and 23 inches between now and 2100. How sure was the scientific community of its predictions, that’s my recollection of it, but you probably know more about it than I do.A big problem with this exchange is that both Hall and Emanuel are incorrect in their assertions.
EMANUEL: I would only simply add to that that the IPCC in making a projection very explicitly excluded any calculation of the melting of land ice. I think they were wise to do that because we don’t understand the physics very well.
HALL: All I was trying to emphasize was that he guessed it 13 feet and he was 12 feet wrong.
EMANUEL: I think that his statement that it was within the realm of possibility is correct.
HALL: I’m not very good on math. In school there were three things I couldn’t do and that is add and subtract.
EMANUEL: The notion that it is within the realm of possibility is correct on his part. That is different than a projection.
HALL: You make a good point and you’ve been a good witness.
First, Hall’s recollection of John Holdren’s testimony is incorrect. On February 18, 2011 Holdren was the sole witness at a Science Committee hearing where Hall asked him about his sea level projection (quotes from this webcast):
HALL: In August, 2006 -- you knew I was going to ask you about the interview that you had with BBC News, didn’t you? – you reportedly said that if the current pace of change continues catastrophic sea level rise would be 4 meters – that is 13 feet – was within the realm of possibility. While you were giving the interview, how sure were you about your prediction? Do you know that the very next year the so-called gold standard view of the scientific consensus by global warming advocates projected that the oceans would rise between 7 and 23 inches, not 13 feet but less than 2 inches (sic) between now and 2100. Let me ask you, how sure was the scientific community of their prediction?It was not the first time that Holdren had been asked about that 2006 BBC interview in which he said:HOLDREN: There are several questions there but let me start with the most recent, the one of sea level rise. At the time there had been two peer reviewed referred publications in the scientific literature that pointed out that twice in the last 19,000 years the rate of sea level went up as much as 3-5 meters per century. Under forcings – that is, influences on the climate, but natural ones in this case – that were in the same range or smaller than the forces that are now being imposed on the climate, we believe mainly by human activity. At that time, therefore, the view that a sea level rise of as much as four meters which was in the middle of the range of 3-5 was a reasonable statement based on what was in the peer reviewed literature. Subsequently newer analyses have reduced that figure somewhat but the upper end of the range remains in the domain of 1-2 meters over the century we’re now in at worse.
When the Intergovernmental Panel on Climate Change arrived at the estimates which you’ve quoted Mr. Chairman the explicitly excluded and they said so in a footnote the dynamic processes which led in the past to these more rapid increases in sea level and they said they were leaving those out because they didn’t believe that the scientific basis for modeling them quantitatively was yet adequate to support a particular number. Since that time – that was the 2007 report of the IPCC whose scientific inputs were finalized in December 2005 – since that time there have been extensive new analyses which have supported the proposition that the sea level rise in this century could be in the range of one to as much as two meters. That is not a particular prediction, the range of uncertainty is large, but even half a meter would be an extremely consequential matter for people and businesses with ocean front property.
[Holdren] added that if the current pace of change continued, a catastrophic sea level rise of 4m (13ft) this century was within the realm of possibility; much higher than previous forecasts.It was also not the first time that Holdren had explained to Congress that he had changed his mind since that interview took place. For instance, in December, 2009 Holdren testified before the House Select Committee on Global Warming and discussed the BBC interview with Congressman James Sensenbrenner (R-WI)
So when Hall told Kerry Emanuel that Holdren had testified that sea levels could rise by 13 feet, he was in fact misrepresenting what Holdren had told him earlier this year, which was that he has changed his views based on more recent research.SENSENBRENNER: You gave an interview in August of 2006 with BBC News in the UK. And you said that a sea-level rise of up to 13 feet was in the realm of possibility. However, that is 11 feet higher than what the IPCC has estimated over this period of time, which is somewhere between seven and 23 inches.
HOLDREN [a bit later in the hearing]: Well, let me, Congressman, take the opportunity of this particular question to answer part of Congressman Sensenbrenner's, because he referred to the IPCC's finding in its fourth assessment report about sea-level rise.
In that report, the IPCC made clear that they were only considering the thermal expansion of seawater and a small contribution from the melting of mountain glaciers in their sea-level rise estimate for the 21st century, leaving out deliberately the mechanism thought to have caused the more rapid rises in sea level that have occurred from time to time in the geologic past.
And the reason they left out those mechanisms that are capable of causing more rapid sea-level rises, they explained in their report, was that we do not yet understand those mechanisms well enough to model them and arrive at the sort of quantitative conclusion that the IPCC was emphasizing. And, in addition, we didn't know at that time, we didn't have enough data to know whether, on balance, the Antarctic ice sheet, the larger of the two, was gaining mass or losing mass.
Since that IPCC report, there has been a great deal of additional work on these questions. We now know that both the Antarctic and the Greenland ice sheet are losing mass. We know that the rate of sea-level rise today is more than twice the rate of sea-level rise averaged over the 20th century.
And the current best estimates of the peak sea-level rise to be expected in this century are one to two meters. That is not as high as my number from 2006. The advancing science has ruled out the high end of that range. But it makes me wrong in 2006 by about a factor of two.
But Emanuel, for whatever reason, decided to defend the statements attributed to Holdren. The result was that Emanuel claimed that Holdren meant something different than Hall suggested and he also indicated that a sea level rise by 2100 was indeed “within the realm of possibility.” Ironically, this contradicts what Holdren actually said, that “advancing science has ruled out the high end of that range.”
Tad Pfeffer, a colleague of mine here at the University of Colorado and an expert on sea level rise reacted to this when I shared it with him as follows, quoted with his permission:
It is my view that sea level is an example of a context in which the scientific community lost control of a narrative (and some might say helped to push it along) in a manner that has contributed to damaging the credibility of the climate science community. Holdren’s 2006 BBC statements were a part of that process, which I discuss more generally in Chapters 7 and 8 of The Climate Fix.Holdren is doing the best he can with a bad situation. His job, and the job of many others, would be a hell of lot simpler if we had never got into the 3-to-5 m SLR in the next century business in the first place. We knew that the circumstances at 18K and 125K are not good analogs for today right from the start (global ice coverage at 18K was very different than today and the evidence for very fast sea level rise at 125K was and remains very weak), but the notion of 3-to-5 m SLR in the next century was allowed to flourish over the next few years regardless. We wrote the 2008 kinematic constraints paper specifically to put a stop to that business, which it has to a large degree, but now the volatile history of the projected numbers, from less than 1 meter at AR4, to several meters post-AR4, to 1-to-2 m max today, are generating a lot of scrutiny, and the 'catastrophic' 3-to-5 m ideas, especially, are being used as bludgeons against people like Holdren who are trying to explain the behavior and train of thought of supposedly rational scientists.
What are the lessons here for experts who testify before Congress?
I can think of several:
1. Decide what your role is. Regardless of which party invites you, decide whether you are there to defend that political party’s views (on science or policy) or if you are there to share what you know about questions for which you have expertise. These are not always the same thing.
2. Appreciate that statements that you make in the media that cherrypick, emphasize extremes (on any side of an issue) or otherwise go out on a limb could set your scientific colleagues up for difficulties in the future when they are asked to defend those statements in a political setting. At that point, the scientist being asked to defend the dodgy statements may face a trade-off between scientific accuracy and political solidarity.
3. Speak for yourself and let others speak for themselves. This is of course can be very difficult when participating in a shared campaign, either for action or a perspective. Even if you are not actively participating in that campaign you may be forced to render a judgement on it, e.g., "Ms. Scientist the IPCC consensus says X, what do you think?"
4. Recognize that when incorrect statements are made in a public setting, the consequences for you as an expert will be much higher than for politicians. That is just the way that it is. The consequences for folksy, grandfatherly Ralph Hall of being wrong will never be as significant as for a scientist testifying before him. So always be able to defend claims that you make.
5. Stick to your area of expertise when testifying as an expert. This seems obvious but is routinely violated.
6. Finally, it should be obvious that a decision to accept an invitation to testify is a political act. No, it does not mean that you shared the political agenda or scientific views of those who invite you. But it does mean that your participation in the process will be more thoughtful and more effective if you have considered your role in the political process, and especially your stance on advocacy versus arbitration. The risk of not thinking these issues through is of course a greater likelihood that you'll simply be a stage prop in a political theater.
On sea level rise, the statements made by Holdren in 2006 to the BBC as AAAS President and environmental activist were far less measured and responsible than his statements made in 2009 and 2011 on the same subject as science advisor to the president before Congress. The difference -- which I attribute as much to setting as to any changes in the science of sea level -- helps to illustrate the difference between an expert who seeks to use science selectively as a basis for political advocacy and one who wishes to faithfully arbitrate scientific questions for policy makers. While these roles are not necessarily mutually exclusive, typically a choice must be made.
Postscript: I emailed a draft of this blog post to Emanuel for his comments and he wrote back that he has no issues with the characterizations made here on the exchange with Hall. He did say that during the hearing he did not catch Hall's reference to 2100 and thought that he meant sea level in the very long term. Emanuel was unaware of Holdren's earlier statements on sea level rise. Nonetheless, Emanuel takes strong issue with Hall's reference to the IPCC sea level rise estimates without noting that they omit land surface ice dynamics. Emanuel remains troubled with how the Republicans are treating climate science.
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