The Mysterious Appeal of the Single-Event Mantra

Did Barack Obama mean for the attention lavished on climate change in his second inaugural address – beginning with the acknowledgement that we “will respond to climate change” because to do otherwise would be to “betray our children” and ending with talk of “care commandeered” and “creeds declared” – to signal that the White House will shortly present a transparent and meaningfully-scaled plan with a mobilization-style timeline for transitioning away from fossil fuels?

Based on the State of the Union address, it would appear the answer is “no.”

Moreover, on the night of the inaugural address, Heather Zichal, Deputy Assistant to the President for Energy and Climate Change, made pretty clear that the Obama Administration’s bar for “not betraying our children” is pretty low. She exclaimed: “We are going to achieve the President’s goal of reducing greenhouse gas emissions by 17 percent [from 2005 levels] by 2020.”

Sure enough, the morning after the inaugural, Press Secretary Jay Carney was there to dispel any notion that the White House understands the scale of global climate disruption, or has a general interest in coherence, saying: “…you don’t pursue action that helps deal with [climate change] just because of the problem itself, but because there are huge opportunities there in alternative energy.”

To be charitable, it’s possible that Carney didn’t mean to suggest that global climate disruption is not sufficient to justify mitigation, merely that “the problem itself” is not the only thing that motivates mitigation.

For whatever reason, Carney also repeated an interesting mantra he had used back in November. He asserted that:

No specific storm or weather event can be tied to climate change…

Press Secretary Jay Carney, January 22, 2012

Shortly after the election, New York Times White House correspondent Mark Landler had asked Barack Obama:

In his endorsement of you, Mayor Bloomberg said he was motivated by the belief that you would do more to confront the threat of climate change than your opponent. Tomorrow you’re going up to New York City, where you’re going to, I assume, see people who are still suffering the effects of Hurricane Sandy, which many people say is further evidence of how a warming globe is changing our weather. What specifically do you plan to do in a second term to tackle the issue of climate change?

Obama responded at length, but here’s the very first sentence of that response:

You know, as you know, Mark, we can’t attribute any particular weather event to climate change.

Barack Obama, November 14, 2012

Variants of the claim “no single weather event can be attributed to climate change” have been made for a long time. Here’s one version from right after Kyoto — COP 3:

…it is impossible to link any individual weather event with climate change…

Tony Juniper, Friends of the Earth Campaigns Director, January 8, 1998

The mantra seems to date back even farther:

It is impossible to ascribe the drought, or any single weather event, to the global warming trend caused by the greenhouse effect, Schneider said.

Stephen Schneider according to Times Union, March 1989

That was in 1989. Suppose we try googling: Hansen, testimony, 1988?

Sure enough:

[James Hansen and other scientists testifying before the Senate panel today] cautioned that it was not possible to attribute a specific heat wave to the greenhouse effect, given the still limited state of knowledge on the subject.

James Hansen according to the NYT, June 24, 1988

But since then, the science of extreme event attribution has developed:

In the past it was often stated that it simply was not possible to make an attribution statement about an individual weather or climate event. However, scientific thinking on this issue has moved on and now it is widely accepted that attribution statements about individual weather or climate events are possible, provided proper account is taken of the probabilistic nature of attribution.

Stott et al. BAMS July, 2012

Let’s review:

▪    We used to say we can’t make attribution statements about single events

▪    We’ve learned a lot since then

▪    We’ve moved on

▪    We can make attribution statements about single events


Nevertheless, the White House used the single-event mantra to justify climate silence:

Q:    Can we expect climate change to come up in his speech today, in his prepared remarks?

MR. CARNEY:  I would not expect that.  He’s focused on the recovery efforts underway in New York in the aftermath of this devastating storm.  The President made clear yesterday that we can’t attribute any one single weather event to climate change.

Press Secretary Jay Carney, November 15, 2012


It’s hard to believe the White House didn’t get the BAMS (Stott et al.) memo and hasn’t been keeping up with climate science, although it’s certainly possible.  (Chris Christie, Governor of New Jersey, for example, hadn’t found any reason to have climate briefings for the last year and a half or so leading up to Sandy.)

Undoubtedly, the virulence and persistence of the single-event mantra have multiple causes, including some cynically political ones. Mysteriously, though, politicians and the media often behave as if the single-event mantra were the single most important thing to say about climate change and extreme events, as if no other message were quite so urgent to convey. Here’s Julia Gillard, speaking in conjunction with explosive forest fires in the extremely extreme Australian heat:

…while you would not put any one event down to climate change … we do know that over time as a result of climate change we are going to see more extreme weather events…

Julia Gillard, January 7, 2013

But alongside whatever ideological, activist, industrial, or political propaganda drivers may exist, a simple conflation has perhaps also contributed to the persistence of the meme, a conflation of two very different variants of the single-event mantra.

Variant 1:

…no single weather event is proof of climate change…

NPR November 2, 2012*

It’s trivially true that no single weather event is proof of climate change. Jeff Sessions was right when he said:

A forest fire is no proof of global warming. Give me a break.

Jeff Sessions (R-AL), August 1, 2012

Schneider made this point back in ’89, too:

Schneider agreed that the link to the global warming is “just circumstantial. It doesn’t prove there’s a greenhouse effect.”

Stephen Schneider according to Times Union, March 1989

Take note, though, NPR and Jeff Sessions, while proving global warming (not the “greenhouse effect” itself though…) was still an issue for Schneider back in 1989, proving that the world is warming is hardly what’s at stake in extreme-event attribution today. We already know that the world is warming: global warming is unequivocal.

Relatedly, having, presumably, been briefed on the science of event attribution following his post-Sandy use of the mantra, Obama erred on the side of incontrovertible truism in the SOTU:

…no single event makes a trend…

Barack Obama, February 12, 2013

While this version of the mantra is plainly true, the question of its mysterious appeal remains. How does this bland truism make its way into the SOTU and survive all the way to delivery?

Possibly, part of the appeal is the obvious need in some circumstances to remind people that single weather events don’t disprove climate change, either.

To the extent that this trivial variant, Variant 1, is conflated with Variant 2 (see below), the appeal of the former could have rubbed off on the latter.

Variant 2:

…it is impossible to attribute any individual event to climate change…

AP, December 8, 2012*

This is presumably (?) the variant that Obama had in mind in his response to Mark Landler.

Go on, do a survey among your friends. How many of them interpreted Obama’s November claim along the lines of Variant 1, along the lines of the SOTU line? Enough, right? These two variants do appear to have been conflated in public discourse.

Frankly, we don’t know what Obama or Carney meant when they used the mantra. While Obama doesn’t typically muddle things as terribly as Sarah Palin (“I’m not one to attribute every activity of man to changes in the climate“), he hasn’t yet given the public any obvious reason to believe he’s got a very good handle on climate concepts (e.g., a McCain/Palin “all of the above, drill, baby drill” approach to fossil fuels is not a coherent response to climate disruption).

To summarize:

▪    The longevity and virulence of the mantra are maybe in part due to conflation of Variant 1 – “doesn’t prove” and “a single event doesn’t make a trend” – and Variant 2 – “can’t be attributed to.”

▪    The “doesn’t prove” variant is true but irrelevant. Global warming is unequivocal. It’s not up for grabs.

▪    The “can’t be attributed to” variant used to be a standard talking point and is still in very wide use, but it is simply no longer valid: there’s a whole scientific subfield devoted to extreme-event attribution:


In recent years the science of event attribution has developed considerably, with a number of studies having been published that quantify the role of human and natural influences on specific weather and climate events.


Stott et al. Attribution of Weather and Climate-Related Extreme Events, WCRP community paper, October  2011

In one sense, that’s the end of the story. In another, it’s just the beginning. See, with all of the above being said and done, we’ve still got the following to deal with:


there are often conflicting messages from scientists about whether [extreme weather and climate-related] events can be linked to specific modes of climate variability or to anthropogenic climate change.


David Karoly, DRAFT Science underpinning the prediction and attribution of extreme events, December, 2012


In Part II of this series, we’ll dive in a bit deeper. Stay tuned.


*Both the AP and the NPR mentions of the mantra are prefaced by “according to scientists” clauses. The AP’s caveat renders its sentence factually true. Many scientists do still repeat the now inaccurate “can’t be attributed to” variant. NPR’s caveat instead makes their claim very misleading because they end up seeming to suggest that “scientists” are cautioning that we just don’t know if the climate is changing.


  1. There's an interesting and unprecedented single event going on now, but I'm sure that even for something so unique it won't be hard to find politicians, journos and even scientists to say we can't be sure what's behind it. Meh.

  2. You might want to check out Annan on the subject if you think this has been laid to rest. He's quite sniffy about single point data (well, scientifically he's got a point, as far as (not much) I understand it) and doesn't seem to have an issue with a response that the IPCC scientists (who AFAIK are rather conservative than radical) will have to "eat crow". (But if we start blaming blog owners for all the comments made on their blogs there will be no end to it. However, the endless proliferation of argument achieves all its purpose, which is to prevent honest discussion.) I exposed myself over there (not comfortable) because of the use Revkin made of it (twice) recently; as is my wont, since I've in the words of another commenter, become a kind of "hall monitor" for the sake of the lurkers (a useless activity, spinning them thar wheels).

    This is being exploited on the intertubes all over the place.

  3. James is making a far more technical point than you imply, Susan. He is saying that the way the attribution problem has been defined will never yield a useful result. He is not saying that there is (nor, I am sure he would want me to add, that there isn't) no way to associate an event with a forcing. He is just saying that the particular way is not useful.

    "The null hypothesis of no anthropogenic influence is always false a priori (and therefore a failure to detect an anthropogenic influence is always a matter of insufficient data). These recent papers point to another, arguably more terminal, problem. Attribution will inevitably fail as the anthropogenic effect increases! ... A moment's thought should confirm that failure to "attribute" in this sense will be an inevitable consequence of gathering a sufficiently long and precise time series of data. The actual value of the scaling factor - ie the ratio of real to modelled forced response - is never going to be precisely 1, for any model, any more than the actual value of the forced response is zero. All such hypotheses based on point estimates are inevitably false, and a failure to reject them only ever meant we didn't have enough data."

    Thinking statistically is hard. I've always been uncomfortable with the attribution question, myself. It seems to have been framed by people who don't understand what statistics is good for and what it isn't. James, of course, is better at turning vague discomfort into a bulletproof argument than I am.

    I have not yet looked at Paulina's reference and don't know whether it will be useful or not. But I agree in principle that the claim that "no weather event can be attributed to a climate forcing" is nonsense, given that events have multiple causes.

    "No weather event by itself can prove or disprove a particular theory of climate" is pretty much true but not useful.

    Mostly, I agree with both James and Paulina that we discuss statistics and attribution and "statistical significance" in the public sphere at great peril. Few scientists understand these matters well.

    There are well-established procedures in experimental fields, so most experimental scientists don't really have to understand them that well, but those procedures don't directly apply in purely observational/theoretical domains.

    I also agree that there is absurd pushback whenever anyone tries to "connect the dots". On the other hand, our language is awkward for such dot-connection and it's difficult to say what is going on both forcefully enough to make a difference and correctly enough not to have it backfire.

  4. Trouble is, I never finished differential equations, so I have to kick the tires and pick my experts. This is going to be a bit long, with apologies in advance. The reason for the background is that my ignorance is probably going to irritate scientific minds, but I'm not quite as vague on the issues as I sound.

    I have actively pushed back both the denier audience and lately Andy himself on Andy Revkin's DotEarth at the New York Times (from the time he wasn't such a lukewarmer nor such a fan of fracking etc.). Before that I followed of climate science primarily through watching weather worldwide. (Andy Skuce has a nice collection of stories about coming to understand at SkepticalScience:

    I'm an artist who taught scientists to draw for many years, so perhaps I have an unusually strong homing instinct for truth and fudging. (You can't fake drawing: you have to risk it all and tell the truth to the best of your ability, nothing else works, but it does require opening your eyes to a broader spectrum of the visual experience which helps open the mind as well.)

    "This", if I understand correctly, is Dr. Annan's recent publication and other related materials which claim that recent attribution studies that attempt to tie in events with scientific modeling and analysis exaggerate the case. With climate sensitivity to CO2 said to be somewhere between 2 and 3 C increase per doubling (560 from 280), Dr. Annan says it's likely to come out on the low end (I don't find this cheering, as 2 is plenty and we're on course for more than one doubling*). Next, we begin to see quite a few comments from less informed but clever arguers, often borrowed from websites that parse this material for export, that in addition to the "cooling" of the last 16 years (yes, I know, that's not supported by the evidence even if you ignore the ENSO spike in 1998) warming has been greatly exaggerated.

    Unfortunately, the standard statement that no single event can be attributed to climate change is easily confused or misstated that no events can be attributed. Obama, for example, has said this recently without a full understanding of its scientific meaning. Dr. Trenberth and others have labored to find a more exact but accurate way to show that warming and day-to-day evidence are not unrelated. That double negative shows the difficulty. We have too many point sources. We also have much more observation than ability to project into the future using modeling or any other techniques I've heard of.

    So the latest statement that attempts to bridge this gap is that no climate is now unaffected by climate change due to greenhouse gas increase over time.

    One more: my good friend Tenney Naumer, nailed the problem in a personal email discussing my experience with Dr. Annan et al.:

    "The thing about models, in the present instance, is that they are incapable of reproducing the current situation - not having all the necessary inputs - and the rapidly compressing timescale. These modelers were thinking in terms of decades or hundreds of years, when it may well all turn on a dime."

    This followed a comment about my father (PW Anderson) who has a somewhat eccentric definition of reductionism, that science all too often avoids what it can't study or quantify. Then we have the further problem, that scientists "use the definition to constrict what you can or cannot do."
    *question: 2-3 C per doubling - but is that for each 280, or does it restart so when we reach 560 the next doubling is 1120 (I always assume it was per 280 ppm).

  5. Yes on Dr. Annan, and his response to me was perfectly civil and helpful. I don't need to understand at a level that exceeds my ability in order to point past misstatements of fact in other locations. I have as good an understanding of what he's getting at as is possible for a moderately scientifically informed layperson (which puts me in the 1% on science, sadly). He is not responsible for the "eat crow" statement from David Young.

    Where he lacks understanding and most particularly sympathy is the fantastical and massive effect of influence peddling and its relevance in promoting inaction. It is his business to do science, and if I understand correctly he lives in the UK. It has not escaped my attention that even fully literate scientists pay attention to local weather in discussions of climate and since the UK has been rather unpleasant lately (those pesky circulations messing up, due to mixups of salinity etc.) it is not surprising that he doesn't have the visceral experience of heat and drought that you do or the northeast corridor experience I spend too much of my time traveling in.

    It would be fun working on these pin angels if our case weren't so desperate.

  6. One more. Links to the relevant DotEarth articles, and note that having revisited the Annan blog I see I have misrepresented who published what, which does not change the sense of what I was trying to say.

    While on their surface they sound reasonable, a closer look reveals a careful bias towards understatement.

  7. Not all of us have the same role.

    James is James and he is a treasure and a delight. But he is not addressing a large audience when he makes these complaints, and by the nature of his approach it will sound as if he is being complacent.

    He is just being rigorous, and it's a crucial role.

    The fact that there is little indication that the climate problem will be solved in practice has not escaped his notice, I think. But that's not what he thinks about and not what he is brilliant about.

  8. A lot of good stuff in there. Tenney and I are having yet another contretemps at the moment but she is a treasure, and the observation she makes, I think, is perfectly valid.

    Re "*question: 2-3 C per doubling – but is that for each 280, or does it restart so when we reach 560 the next doubling is 1120 (I always assume it was per 280 ppm)." it is the latter. The forcing regime is such that the warming is proportional to the logarithm of the concentration. This benefit is not all that wonderful in practice for reasons I ought to write about some day.

    Re James, again it is little wonder that you misunderstand. I don't think he is happy or unhappy about 2 C or 3 C. I think he is unhappy that so many scientists fail to understand his point about why the fat tail problem on the temperature sensitivity is an artifact. This doesn't speak well for science. His persistence on the point speaks well of him as a scientist in the classical vein. I think he's a member of an endangered species, more's the pity for all of us.

    But he's not talking to the general public. I'm not sure he is capable or interested in doing that. To put him in the same bag as say Judith Curry or Roger Pielke does him a great disservice. (I would note in passing that neither of them is particularly fond of him either!)

  9. Thanks.

    Please, I wouldn't bother with Dr. Annan if he was not respected by a number of people I respect, and I have an inkling of the scientific issues. Nor was he discourteous to me, which says a lot sice I offered some provocation and the British tradition is not tolerant of either women or amateurs. My primary concern was to try to understand what he was saying so that when I encountered the arguments elsewhere, distorted, I could honestly indicate that real science was being twisted to support an untenable position and the original stated otherwise.

    I would *never* put him in the same category as the grossly intellectually dishonest Dr. Curry (not only with others but I believe with herself) or Pielke Jr. who supports untenable positions that are actively harmful to the work we all need to do, though in his case I only know this at second hand.

  10. Hi Susan,

    Thanks for your responses.

    Still not really sure about the "laid to rest" part... 🙂 For clarity, I assume the concept of attribution in climate science will continue to develop... Heck, not even the mysterious appeal of the single event mantra has been laid to rest... although it should have been! 🙂

    I'm curious whether the development of the concept of attribution will be incremental or if there will be any kind of more transformative-like shifts.

    Anyway, the thrust of the post is really just to call attention to the fact that this is indeed a real mantra. The mantra is repeated in odd contexts, almost ritualistically, as I tried to show with some of the Obama et al. and other recent examples.

    Meanwhile, people are busy doing extreme event attribution studies, including on single events...

    Yes, there's definitely a tendency to conflate ideas in conjunction with the single event mantra. For instance, sometimes people forget that the warming of the climate system is unequivocal and take the deepity truism "no single event proves climate change" as some kind of refutation of the unequivocality of the warming of the climate system.... As if the burden were on this or that event and hadn't already been met.

    Yes, people also take the falsity "no single event can be attributed to climate change" as a truth and also conflate it with the deepity above and presumably with other variants, too.

    The "no single event can be attributed to..." mantra is false. And it confuses people, a lot of people, a lot. And it is used to promote climate silence. When it comes to things to lay to rest, the mantra is a top contender.

  11. James does say some things, outside the area of his direct expertise, which play down the threats we face fromanthropogenic climate change though. These certainly are picked up on by a larger audience.

  12. Thanks everyone. I will repeat the money quote from Tenney, as the html didn't bold it properly:

    The thing about models, in the present instance, is that they are incapable of reproducing the current situation – not having all the necessary inputs – and the rapidly compressing timescale. These modelers were thinking in terms of decades or hundreds of years, when it may well all turn on a dime.

    In fact, I think this is part of what Dr. Annan is researching.

    One more question: I think I understand about the fat tail but can somebody make it a bit clearer? As I understand it, it's the slimmer possibilities for greater warming per doubling, sloppily understood by me as the increasing likelihood of reaching tipping points sooner rather than later.

    David Benson, thanks for the info. The cultural context remains a part of people's framework for processing information; many of my habits arise from early childhood when I was taught to care for others, respect the environment, and exercise critical thinking in a liberal political household.

  13. Clarification: since the fat tail represents lesser possibilities which appear to be in some cases to better represent observations, why follow a theoretical argument against paying attention to them?

  14. Charney equilibrium climate sensitivity (ecs) is a simplification of Terra's climate which only can properly be measured by a system (such as a climate model) without cryosphere changes including methane releases from melting permafrost, etc. So ecs can be estimated for a time of equilibrium such as during last glacial maximum or during the Holocene climactic optimum.

    The fat tail refers to the probability that ecs is actually much larger than the ensemble of estimates. It is most likely an artifact of the Bayesian methods used to find the more likely range of values.

    That said, ecs is itself probably an underestimate of the full climate sensitivity including cryrosphere changes. That is termed 'Earth system sensitivity' or some such phrase. The current estimates are around 4.5+ K for 2xCO2.

  15. 4.5+ K for doubling of CO2?

    Now that's about double the previous 2-3 C that everyone was arguing about. From my point of view, that's real danger of extinction. I don't disagree, but explaining that in highly technical terms isn't going to broaden any audience, shut up any naysayers, and makes the "fat tail" irrelevant.

    Paula Essunger, thanks for your work. You are quite right, mantras are troublesome. Starting near the top, Mr. Obama appears to misunderstand. But when it comes to PR, the money's mostly on promoting ignorance.

  16. David: "The fat tail refers to the probability that ecs is actually much larger than the ensemble of estimates. It is most likely an artifact of the Bayesian methods used to find the more likely range of values."

    Or the lack of Bayesian methods, which the Bayesian interprets as using the implausible uniform prior (ie, sensitivity could be anything).

    "That said, ecs is itself probably an underestimate of the full climate sensitivity including cryrosphere changes. That is termed ‘Earth system sensitivity’ or some such phrase. The current estimates are around 4.5+ K for 2xCO2."


    Anyway if we stick with BAU we will make earth hot enough to free the carbon of a lot of permafrost and probably some clathrates as well. CO2 under BAU will get much higher than it has been in a long time, higher than current permafrost has experienced. The only to learn what earth system sensitivity is (from our current starting point) is to go ahead and double CO2 and see what happens.

  17. Pingback: Another Week of GW News, March 3, 2012 – A Few Things Ill Considered

  18. There are important things which are turning out worse than expected, but ecs is not itself one of them. There is no new information supporting the scary fat tail of ecs to my knowledge.

    This relates to the mistake of calling the problem "global warming" when global warming is only a part of the problem.

  19. Paula Essunger has hosted a discussion that has moved far from her original point, so I think this is as good a place as any to point out a new DotEarth article which is rather good - if you are interested in a reasoned defense of Andy Revkin's position in the context of reality - on the newest Science article on "Abrupt Global Warming" (which is a moderate take on abrupt in my very personal opinion):

  20. Yes, I'm proud to be leading the opposition this time around. Must be Thursday (long story, but it's my "free" day). Still, it's better than the usual.

    John Mashey made a fascinating connection - it appears there's some evidence humans have always changed climate with their farming.

    Nice to see people are getting wholly riled, and the denial cadre left behind for a few hours.

  21. Sorry, meant to add Mashey's link:

    USA Today is doing an excellent job these days. New York Times has a new article about contemporary farming that is also better than the usual:

    Silly title, "Hicks Nix Climate Fix," belies its content.

  22. No kidding. Prompted a question for me. Revkin's story about a researcher complaining about being misquoted but never ever having contacted a reporter to correct a story made a big impression on me when I read it back when. Given how hard it can be to get corrections made, I have a bit more sympathy for the researcher now (but the thrust of the story was clearly that the person had never even tried).

    But (and here's where the article you linked comes in) what about the researcher / press office (or department communications) interface? What does the process look like at that level? Do researchers typically sign off on final versions of press releases? Does it vary widely? (I recall more than one response from a scientist along the lines of: "oh it's out? I haven't seen it.")

    What about overly nice people, who feel bad about an editor/comms person who got something wrong? How do those kinds of considerations factor into the persistence of a meme like this one?

    It's hard to imagine anyone issuing a correction to a press release stating that a mistake was made in editing the press release and that "not possible" should be changed to "hard," for instance. But it's also odd that this is hard to imagine.

  23. Mid-Pliocene warm period (actually updated to mid-Piacenzian since the stratigraphers switched the first chunk of the Pliocene to the Pleistocene) was 2-3C warmer with current CO2, maybe less. Doubling gets you a lot more at equilibrium. We probably need to go back to the Eocene for levels like that (maybe very early Oligocene). The Eocene was uncoincidentally the warmest time of the entire Phanerozoic.

  24. That would be Lunt et al. with GS as co-author, I believe.

    But I should take the opportunity to note that for us the big concern about the MPWP isn't the global average temps, it's the extreme Arctic temps (the giant camels currently in the headlines refer) that the models are entirely unable to replicate. There's an abrupt change mechanism lurking in that data, and it may well be that current Arctic sea ice loss is the harbinger of it. Jack up Arctic summer temps that much (+18C IIRC) and it's kind of like applying a blowtorch to the GIS. Of course the polar amplification would affect the south, too, although perhaps to a lesser extent, but of course the WAIS and a good chunk of the EAIS would also need to go to reach the 25+ meters SLR of the MPWP.

    That said, IMO worse things are possible under anthropogenic forcing, thinking in particular of the recent proposal of Pagani and co-authors that abrupt Antarctic permafrost loss is key to the Eocene hyperthermals.

    Just sayin'.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.