15 February 2013

A Case for Playing it Straight

I have just participated in a lengthy Twitter exchange with Marshall Shepherd (@DrShephard2013), a professor at the University of Georgia and President of the American Meteorological Society. The occasion for the exchange was Dr. Shepherd's presentation yesterday at a Congressional Briefing sponsored by the Senate Committee on Environment and Public Works (his prepared remarks can be found here in PDF). The briefing focused on "the latest trends and scientific evidence related to the growing impacts associated with climate change."

Three other scientists testified at the briefing, but I am not interested in what they had to say. Shepherd's remarks are of interest because he is the President of a major scientific society. He was not at the briefing to present his personal opinions, but rather in his role as a leader and representative of the scientific community. Thus, in my view of the obligations of such a role, he had a duty to play it straight.

Unfortunately, as is so often a case when leaders in the climate science community find themselves before an audience of policy makers, on extreme events they go rogue, saying all sorts of things with little or no scientific basis. Even if the scientist includes many accurate statements in his/her remarks (such as the reality of significant risks of human-caused climate change), the presence of horsemeat ruins the lasagne.

Let's take a step back. The science on climate change, extreme events and disaster costs is clear and unambiguous. You don't need to take my word for it, you can find the science well summarized in the IPCC SREX. And if you don't like the IPCC you can find an array of peer-reviewed literature. I am happy to debate this topic with all comers as the data and analyses overwhelming support the claims below.

In a nutshell here is the state of the science (here I focus on the US as Shepherd did):
Any presentation of the state of the science of extreme events and climate change that does not explicitly acknowledge the important conclusions above from the IPCC and other assessments is incomplete and potentially misleading.

What did Shepherd say in his briefing?
  • He said his spouse can see the impacts of recent extremes
  • Weather is now on steroids, like baseball players
  • Weather is like your mood, climate is like your personality
  • He cites two scientists quoted in The Guardian saying that all weather is affected by climate change
  • The impact of climate change can be seen in the price of Cheerios
  • The recent Northeast blizzard is related to climate change
  • Suggests that climate change is "loading the dice for extremes"
Shepherd seems a great guy, and he has a fantastic demeanor on Twitter. But I'm sorry, this is horsemeat. (And to be clear, yes, there is more than just horsemeat in Shepherd's lasagne.)

As President of the AMS Shepherd does not have the luxury of using that platform to share his personal opinions on climate science that may diverge from that of the community which he represents, much less stretch or misrepresent broader findings. Leaders of important institutions of science -- like the AMS -- speak for more than themselves when presenting science in public fora. They also represent the credibility of their institution and climate science more generally.

In formal settings such as the briefing yesterday where experts meet politicians, I fully expect Democrats and Republicans to cherrypick experts convenient to the arguments they wish to see made. That is politics as usual. Leading scientific institutions play that same game with some considerable risk to their credibility.

My advice? On extreme events, please, just play it straight.


  1. I would argue that rather than 'going rogue,' Shepherd sees himself as marching in lockstep with his tribe. When was the last time you saw a major scientific figure stand up in public and tell people that no measurable effect of CO2 can be seen in the so-called 'extreme events?' Not in a blog - in a newsmaking venue. They either say exactly what Shepherd said, or they keep their mouths shut.

    This leads me naturally to ask why they do it. Personally, when I see a group of people unwilling to argue on the facts - as they understand them - I find it reasonable to question their understanding of the facts. Or in this case, if scientists have to lie to me to convince me of their understanding of climate change, I think I have a perfect right to assume, without knowing all the details, that their position is not likely to hold water. That is, if THEY don't trust the facts to support their position, why should I?

  2. Sheperd has been in Twitter debates with me, too. While he is infinitely better to argue with, than say Gleick, Shepherd offers little of substance, and ignores the evidence given. As Roger found, he ignores even the IPCC.

    In our first exchange, he used @PresidentAMS as his Twitter address. I questioned him on this, and he has since changed.




  3. There is more behind this this behavior. I quote from another commentator:
    A very telling phrase: ”Climate is the average of the weather….’. But, that is not what climate scientists like Slingo believe. For them ‘climate drives weather’. This is the inversion of thought which distinguishes the traditional meteorological paradigm from that of the (new) climate scientist. The former is informed by a straightforward empiricist view of the world – the latter by a form of rationalism based upon the Platonic concept that there are certain ideal and immutable laws (in this case the laws of radiation physics and thermodynamics) from which the future of the climate can be deduced and modelled.
    I think this inversion is prevalent and explains why empirical observations are so readily dismissed by "scientists."

  4. Roger, thank you for your integrity in this area and for sticking with it. A very basic question on this: "Disaster losses normalized for societal changes show no residual trends (US, other regions or globally)."

    Do you think losses normalized for societal changes are a better metric to give the man in the street an idea how we're doing (and the policy maker, come to that) than the even more direct one of human deaths caused by disasters?

  5. In a health care setting cross contamination is something to be avoided. Climate Science has been cross contaminated by politics and I see no preventative measure to cure it.

  6. Roger:
    Well said. Shepherd's statements on extreme events are pernicious on many fronts. It is astonishing the lengths he goes to in the twitter exchange to simply acknowledge the accuracy and validity of the points that you raised. It bodes ill for further discussions.

  7. Roger, I'm really disappointed in this blog post from you.

    I've got the text of Marshall's Senate briefing comments in front of me, side-by-side on the screen with your comments above. I'm trying, so far in vain, to find any place in which what he said contradicts what you wanted to have said.

    Marshall's briefing is studded with citations of the AMS Climate Change Statement. But you have mischaracterized his remarks as some kind of Palinesque "going rogue" moment, when it was not.

    What I find most insulting, as a teacher, is your bullet points that mock his attempts to convey (as the stellar teacher Marshall is) the complexities of climate to non-specialists. I use some of the same analogies, and they are not invalid educationally, nor are they inaccurate scientifically.

    I'm sure Marshall can provide you with his prepared briefing text. I will await from you a sober and measured discussion of precisely what you think is misrepresented in them. But it will have to be something more substantive than the sniggering "more than just horsemeat" level of your comments here.

  8. John, Can you post a link to Shepherd's Senate comments?

  9. -8-bernie

    They are linked in the post above, here:


  10. Roger:
    It seems to me that the core issue is how one can falsify the "humans are increasing the probability of extreme weather" argument and what are the pre-conditions for folks like Shepherd to make such assertions - given the human tendency to overweight recent events and the ever present confirmation bias. It strikes me that you are calling on Shepherd to adhere to a higher standard of rigor than appears in his testimony. It is notable that he is far more circumspect about data and possible explanantions that do not support his primary argument. I was in Boston for the blizzard of 78 - why does that weather event not enter the discussion?

  11. Imagine the church appointed a physicist to be the next pope. He announces that there will be no more fairy stories about heaven, hell or miracles. Everything must adhere to the laws of physics.

    It would be the instantaneous end of the longest franchise in history.

  12. John Knox,
    I too read Dr. Marshall’s senate briefing along with Dr. Pielke’s blog post and disagree with what you said. Dr. Marshall did adequately convey the complexities of climate because there is no suggestion that any of his observations could be caused by anything other than global warming. Trenbreth’s quote “climate change is affecting all weather now because the background conditions are so changed – more heat in the system and moisture in the air” was not in the AMS Climate Change Statement for good reason – it is an unfalsifiable hypothesis.

  13. I haven't read the testimony, so perhaps in context, Dr. Shepherd remarks were more nuanced. The following quote from Shepherd (which was tweeted by the AMS Policy Program) sounds inaccurate to me, though:

    "Climate Change is like loading a dice. A storm like Sandy is rolling two 6's. We are adding another 6 to the dice"

    I'm not an expert on tropical dynamics, but as I understand it, the latest research indicates that hurricane frequency is expected to stay the same or decrease as the climate warms. Storm intensity is more uncertain. Thus, it's quite possible that storms like Sandy will become less frequent in a warmer climate.

    In light of that, I'd say that Dr. Shepherd's statement is misleading, to say the least.

  14. wxmarc #13

    re: accuracy and inaccuracy

    Lest you introduce another "insult" to teachers, you need to be aware that "scientifically inaccurate" or "not scientifically inaccurate" is often in the eye of the beholder, and teaching moments sometimes are considered sufficiently valuable so as to overcome limitations imposed on mere mortals.

  15. Two things;

    1: Your summary of the 'state of the science' is incomplete. You refer only to data which supports your contention that 'nothing has changed'. The reality is that there is also research suggesting that many of these items you claim to be unquestionably unchanged actually HAVE been impacted. There is currently considerable dispute on many of these details. However, TEMPERATURE change, including 'extreme' temperature events is NOT in dispute. The frequency and severity of extreme high temperature events have both increased.

    2: You refer to a statement that, "all weather is affected by climate change" as "horsemeat". Here you are simply in error. Climate is weather in aggregate. If weather has not changed then climate CANNOT do so. The global temperature anomaly has not gone up over the past 100 years without average daily temperatures (i.e. 'weather') being impacted. Climate change IS weather change. They are the same thing viewed from two different reference frames. You cannot rationally acknowledge the existence of a forest fire (or climate change) and simultaneously question whether any trees are burning (or weather changing).

  16. -15-Conrad Dunkerson

    Thanks for the comment. If you would like to suggest any literature that contradicts or challenges the 8 bullet points I list above, I would welcome it.


  17. For the US a good summary can be found at;


    The point being, that even if you disagree with findings that there HAVE been increases in some extreme events the fact is that these reports EXIST. Indeed, even the IPCC SREX which you cite states;

    "There is evidence from observations gathered since 1950 of change in some extremes."

    "There have been statistically significant trends in the number of heavy precipitation events in some regions."

    "There is evidence that some extremes have changed as a result of anthropogenic influences, including
    increases in atmospheric concentrations of greenhouse gases."

    Et cetera.

    There is thus NOT a "clear and unambiguous" case that the "state of the science" is that extreme events are not increasing.

  18. -17Conrad Dunkerson

    Thanks much, I summarized the CCSP report here:


    And that report is perfectly consistent with what I have written here. At no time have I said that there have been no changes in all metrics of extremes.


  19. CB Dunkerson, let's take one so called extreme, Sandy. Surely you don't attribute climate change to Sandy knowing full well that global temps have been flat for the past decade and a half.

  20. Um. Horsemeat is fine. I've had fantastic horsemeat steaks in Spain. And Donkey Salami. So not a term to use like "bullshit"...

  21. " ... US hurricane landfall frequency or intensity have not increased ..."

    But...but...but... Marshall Shepherd himself said they would be at least more intense back in 2004, as seen in this 2004 CNN article, 2nd papragraph ( http://web.archive.org/web/20040904022239/http://www.cnn.com/2004/TECH/science/09/03/hurricane.science.cnn.ap/index.html )

    "Over the past few years, we've seen an increasing trend toward greater activity in the Atlantic Basin and increased strength in storms," said Marshall Shepherd, a research meteorologist at NASA's Goddard Space Flight Center. "[That] has been leading us to believe that we are going to start seeing more intense hurricanes. That may be bearing itself out right now."