Weather or Not

February 11, 2010

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People have been spinning the climate issue for some time now, and Roger makes a point that really needs to be made over and over again: weather ain’t climate, no matter how much we might like to pretend (believe?) that any given weather event is or is not the result of shifts in the climate.

I might however offer this addendum to his post. He says, at one point, this:

Further, it is professionally irresponsible for scientists to claim that some observed weather is “consistent with” long-term predictions of climate change. Any and all weather fits this criteria. Similarly, any and all weather is also “consistent with” failing predictions of long-term climate change. The “consistent with” canard is purposely misleading.

If the suggestion (S1) that ‘some weather event (W) is “consistent with” climate projections’ is taken as (or employed in the) affirmation of the strength of the models, then Roger is correct to point out that S1 is both misleading and false.

But if the suggestion (S2) that ‘some weather event (W) is “consistent with” climate projections’ is uttered in response to claims that somehow recent weather events undermine the climate science, then S2 is not misleading and false.

What matters is not whether W can or cannot be taken as evidence for climate change, but whether the utterance (either S1 or S2) is employed in the service of defending or supporting the governing position. That is determined by the use of the utterance, and not strictly by the semantics of the statement. S1 and s2, it should be clear, are identical statements; they are not, however, identical utterances.

UPDATE: Here’s what David Roberts at Grist has to say.



  1. I’d suggest that the proper response to a claim that “somehow recent weather events undermine the climate science” is “no, weather is not climate.”

    To suggest that the weather is “consistent with” climate projections is misleading in any context. In the context of S2, it does not respond to the more fundamental problem with S2, which is not a matter of consistency, but rather incongruity. It is not possible for weather to undermine claims about climate.

  2. Well, I agree with you that it is certainly a better response to say that “weather is not climate.” That’s a fine response. But it’s not misleading to say that nothing about the current weather is inconsistent with the climate models; or equally that the current weather is consistent with climate models. Why? Because weather is not climate.

    So again, you’re right that it’s not possible for weather to undermine claims about climate, but it’s not correct to suggest that it is somehow wrong to respond to someone who makes a consistency claim — S2 is a response to the charge, remember, that “W is inconsistent with CC.” To that charge it is appropriate to resist — to say that it is not inconsistent, that it is instead consistent, with CC.

    • To the extent that S2 can be avoided, just avoid it by saying “weather is not climate”. Particularly when such utterances move through the public arena (via mass media for instance), there is a good chance that the subtleties of your point here get lost (by only quoting the response, by not properly appreciating the art of semantics etc…)

  3. So long as the response is caveated with the disclaimer that “of course, any and all weather is consistent with” CC I’m with you.

    But to suggest consistency in the absence of such a disclaimer is to imply — or lend oneself to the (mis)interpretation — that there is in fact a class of weather which would be “inconsistent with” CC — which of course there is not.

  4. Of course a very common use of the term ‘consistent with’ is in a statement something like:

    “This drought/heat wave/heavy rainstorm we are experiencing is consistent with what models expect to become more common in future”

    I see no logical problem there since there are plenty of events (depending on region and season) that are expected to become less common. It is not a statement about current attribution, nor is it an implicit confirmation of the model, merely a projection made flesh so to speak.

  5. Let us simplify this. Assume that we have a day in August where the temperature is below freezing. It is perfectly meaningful to say that the event is “inconsistent with climate”. OTOH, if it hits 100 in Mobile on August 15, that is “perfectly consistent with the climate”.

    Another example, assume that the minimum Arctic ice extent in 2011 matches that of 1980. That would be inconsistent with climate trends.

    Another example, assume that there are repeated record heat waves across the southwest this summer. That would be consistent with the climate trends in the last ten or twenty years. OTOH if a summer brought a string of record cold days across the southwest, that would be inconsistent with the recent climate trends

    Climate is the statistical distribution from which weather is drawn. Distributions have outliers, but they also have strong central tendencies. We can say meaningful things about both at the same time. Weather is not climate, but weather and climate are intimately related.

    • Eli:

      I don’t follow your logic on this one.

      Are you saying that the low for a date and the high for a date are not consistent with climate?

      I understood the low and high for a particular date in history to be the range over which climate had varied on that particular date, over the temperature record.

      I fall into the camp which says that the weather – taken over time – is what defines the climate.

      So it doesn’t make sense to say that the weather on a particular date is consistent with or inconsistent with the climate.

      • Rick,

        Every datum is a point of evidence. Any datum can either be consistent or not with a prediction. It is the accumulation of data that lends credence to a prediction, i.e., the weight of evidence. If one cannot judge whether any particular datum is or is not (relatively) consistent with a prediction, then there is no way (in the long run) to judge the prediction.

        In this case the prediction is that climate change due to AGW will likely result in more frequent extreme precipitation events. Though these storms, considered in isolation, do not provide conclusive proof of increased frequency, it is not credible to conclude they are not extreme precipitation events.

        To channel Wittgenstein, I would suggest Roger’s consistent incongruity of the rules of meaning has the consistency of bovine excrement.

        With all due respect.

  6. […] Consistency February 12, 2010 Democracy Now offers a good example of what I was talking about yesterday. (Hat tip to Max.) Actually, the discussion is all over the place.  The NY Times also has a nice […]

  7. If a particular theory says that a particular kind of event is likely to occur more frequently, or with more intensity, and then such an event occurs, there is nothing unprofessional about saying the event is consistent with the theory. It may be subject to misinterpretation, as just about any statement can be in the politically-charged atmosphere of climate science. But it is not unprofessional or inaccurate to point this out regarding events that will feed into the long-term trend. Caveats may help, but often get edited out even if a reporter chooses to include them.

  8. In case anyone is still wondering what this is about:


    Climate science statement from the Met Office, NERC and the Royal Society

    “We expect some of the most significant impacts of climate change to occur when natural variability is exacerbated by long-term global warming, so that even small changes in global temperatures can produce damaging local and regional effects. Year on year the evidence is growing that damaging climate and weather events – potentially intensified by global warming – are already happening and beginning to affect society and ecosystems. This includes:

    * In the UK, heavier daily rainfall leading to local flooding such as in the summer of 2007;
    * Increased risk of summer heat waves such as the summers of 2003 across the UK and Europe;
    * Around the world, increasing incidence of extreme weather events with unprecedented levels of damage to society and infrastructure. This year’s unusually destructive typhoon season in South East Asia, while not easy to attribute directly to climate change, illustrates the vulnerabilities to such events;
    * Sea level rises leading to dangerous exposure of populations in, for example, Bangladesh, the Maldives and other island states;
    * Persistent droughts, leading to pressures on water and food resources, and the increasing incidence of forest fires in regions where future projections indicate long term reductions in rainfall, such as South West Australia and the Mediterranean.

    These emerging signals are consistent with what we expect from our projections, giving us confidence in the science and models that underpin them. In the absence of action to mitigate climate change, we can expect much larger changes in the coming decades than have been seen so far.”

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