Word of the Day: Pluvial

The folks running the Climate Working Group summer retreat on drought were kind enough to invite me up to Santa Fe this week. I spent most of the time listening, but they also extended the huge kindness of inviting me to speak. I think they hoped I could explain the rituals of my somewhat mystifying media tribe, rituals that I know leave many scientists puzzled.

I don’t know if I was much help. My central point is that we can’t do what many scientists expect of us: make the public understand the science.

Scientists are not the only ones laboring under this misapprehension. Lots of people see the world very clearly, and believe that if the news media only was smart enough to see things this way too and share that with “the public,” whatever it is that needs fixing would be fixed.

In particular, it seems we can have little effect on the outcome of scientized political debates (climate change, nuclear waste, evolution/intelligent design) in which the policy/political actors have firm views and/or preexisting biases that are unlikely to be moved by media reporting. (This is the foundation for the question I posed this afternoon to Chris Mooney and Matthew Nisbett regarding their Skeptical Inquirer piece about major media coverage of the hurricane-global warming issue.)

But if we can’t fix things, what we can do is provide a reasonable foundation of common knowledge for civic discourse, informing those who aren’t actors with firm views. And in scientific issues that have public policy implications, but that are not framed as scientized debates, while we can’t fix things, we can contribute to progress. That’s why drought seems like a sweet spot for me, an area where I can usefully explain science to the public without getting tangled in the leash.

Which brings me to my word of the day.

There is no word for the opposite of “drought.” Or, more precisely, there is a word (“pluvial”), but no one uses it. This is not the cause of our problems, but rather is a result of the fact that we don’t recognize the normal range of climate variability. When it’s unusually wet for a long time, we think of it as normal and act like it’ll go on forever. When it gets dry, we call it a “drought” and pine for its demise.

My great example was an AP story from last weekend about drought in southern Alabama. It seems to be blaming drought for the end of corn farming in the region. In southern Alabama, the period from about 1970 to 2000 was unusually wet as compared to the longer term record. They were in a decadal-scale pluvial, but they don’t’ seem to have realized it.

If you don’t notice it’s wet, you’re going to be screwed when it gets dry. It seems as though it’s worth my journalistic time to point this out. I’ve had a lot of traction on this point in recent years. But then, we’re in a drought. It’ll be interesting to see how well it works once New Mexico’s climate gets wet again.


  1. Damn, John! I like reading what you write, but I don’t usually get rocked back in my chair thinking “Gee! He’s completely right and I hadn’t thought of that at all” Twice, no less, in this case.

    The summarisation that the media cannot *make* the public understand science is something that probably needs to be mentioned by credible journalists more often. I’ve been guilty of thinking “stupid media, that won’t help” when reading science reporting, but I don’t think I’ve ever thought you were taking on “Mission: Impossible”.

    (The paragraphs about not reporting unusual wet periods as seriously as droughts was the second bit that hit me.)

    I’m going to take credit for knowing what pluvial meant, though. Only because it comes up in crosswords sometimes and I didn’t know it the first time I saw it.

    Thanks for the inadvertent bat about the head with the cluestick.

  2. Excellent post, John.

    We might not be able to make the horse drink, but we have a responsibility to lead it to clean water.

    Re: your conclusion that you can’t make people understand, you relate something here:

    This is not the cause of our problems, but rather is a result of the fact that we don’t recognize the normal range of climate variability.

    that somewhat disagrees with your premise.

    You (the journalists ‘you’) can give people information that helps them understand that rainfall is variable and explain why it matters; this gets the public a long way down the path to understanding, and that is part of the process.

    Understanding is a process, not an isolated discrete event. Conveying information clearly helps understanding – you can’t do it all, but you can make it easier.

    That is: you can’t make the public drink, but you can lead them to clean water.



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  4. Riding the elevator up to my office today I came to realization that I knew what a “drought” was, but I didn’t know what the opposite of a drought was. I landed here thanks to the wonder of Google. Thanks for helping me fill out another of the seemingly endless small, empty corners of my brain.

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