Comment on El Nino Post on 538

The 538 comment system appears to not be working, probably because of my current highly suspicious location, so I figured I'd put my comment here (since I spent a whole minute writing it):

"Long-range forecast models have come to a consensus recently that a minor to moderate El Niño pattern may develop six to nine months from now.

That just isn't true. Forecasts suggest a 50-50 chance of El Nino, but this is hard to predict. There is no consensus that an El Nino will develop among forecasters who are always super cautious about this prediction and there is only a 50-50 chance.

Also, I see no one saying it would be a moderate El Nino. Do yo have a reference for that? Some, in private, are putting their money on a strong El Nino if one happens, but not saying so publicly because the uncertainty is so high it would be irresponsible (or embarrassing if wrong!)

Regarding California's lack of water, this may be harder to predict. An El Nino may or may not bring "drenching rains" but it is snow pack that probably matters more, and a single year of El Nino heavy rains may do nothing, so you may have that right. Overall, I agree that the earlier statements about ho El Nino will fix everything were somewhat bogus because, in part, they were being made when ENSO forecasts woul dhave been very tricky and they aren't much better now.

Finally what is the behavior of a longish term oscillation like ENSO under dramatically changing climate, an the effects of that pattern on other patterns? ENSO affects climate by altering things like jet stream behavior and trade winds. But the Arctic is kicking butt in that area these days. Will we be seeing a major face-off between ENSO oscillation and Arctic Amplification???

Here's the post that comment goes with.

I haven't said much a out 538 and recent forays into climate and weather, but at the moment I'd classify 538 as a Junk Science site, which is highly disappointing. Let's hope Nate Silver decides to fix that. Taking on an area of science and totally woo-ing out is reputation destroying stuff. It's not like there isn't a plethora of talent out there he could tap into.

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“Long-range forecast models have come to a consensus recently that a minor to moderate El Niño pattern may develop six to nine months from now."

This is technically correct, but semantically meaningless.

What's the probability range encompassed by the phrase "may develop"? Say a 20%-80% chance of development? So this just says that the models agree that the range of probability of an El Nino is somewhere in that range.

By Windchaser (not verified) on 03 Apr 2014 #permalink

The probability of El Nino is just over 50%, not sure of the c.i.

Since most years one does not develop, a 50 percent chance is high. But again I have seen no one saying moderate to mild. I only hear people saying two things: a) it could happen this year and b) it looks like a big one.

Ha, I was annoyed by the post, too. It's as though the rest of the available data on which people make these predictions simply doesn't exist to the 538 post, it's statistical hooey with no context or background. Anybody reading it without any background came out _less_ informed.

The reality is that there's a huge pool of very hot water moving East in the equatorial pacific, under the surface -- the very edge of it is just starting to come up to the surface now in the East Pacific. This is measurable, we have these measurements. And it's really very strongly warm -- probably warmer than we've ever seen, and certainly at least as strong as the 97/98 event.

Now, that in itself doesn't guarantee the strength of the El Nino over time, or even necessarily that we'll have one, there are plenty of factors and we don't necessarily know them all.

The 50% is a little out of date at this point, they don't update those predictions but once a month, so that 50% is from mid march -- meanwhile, it's actually, like, surfacing now, so unless it just suddenly sort of fizzles out for... unknown reasons... I'd say it's a pretty sure bet that some kind of El Nino is about to try to get going. That pool of incredibly warm subsurface water isn't just going to disappear, at any rate.

There's more data to look at here than doing some very basic statistical glancing at some historical data and referencing a model spread that has been strongly trending more and more "El Nino-y" for the last several months.

As for CA rainfall and the like, there aren't guarantees, and CA really only sees much change from strong events, but we're not totally in the dark when it comes to how these effects tend to shift the jet stream, etc. We have plenty to learn, but the sum of what we do know goes well beyond "gosh, we only have these few historical data points, so we have absolutely no idea!"

Some data for anybody interested:

PS I only just now noticed that he specifically used _central valley_ rainfall to illustrate the lack of correlation. I live here and have for a long time. For complicated reasons, that is a very stupid thing to do, and especially taken as the whole valley instead of separating it into the _distinct_ Sacramento Valley and San Joaquin Valley. Both always vary pretty widely in annual rainfall, but the southern San Joaquin is a desert by precip, and most of the relevant watersheds that feed the state through summer are in the north half of the state or so (none related to any of the valley.)

The whole central valley is in a rain shadow from the coast range -- the north is naturally a prairie, and seasonal wetland from river flows (not direct rainfall!) and the south is very, very dry. I'm shocked, shocked I say, that the data here is muddled.

That data table he spent time making is utterly useless. Why the heck would he pick central valley rainfall as some sort of reference?

Tamino would be the perfect 538 science blogger. What he does for science and climate is exactly what Nate does for politics and elections.

Honestly, Open Mind should just be ported over to 538.

By Rob Honeycutt (not verified) on 04 Apr 2014 #permalink