Cautionary Note on El Niño Forecasts
Learn the cautionary note on El Niño forecasts, including the conventional wisdom of paying attention to the ENSO forecasts, and the analog method using existing climate model simulations.
Gavin Schmidt
Climate scientist, occasional juggler, even more occasional author, curious about how the world works.
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#Elniño is trending for obvious reasons, but let me inject a note of caution... pic.twitter.com/zg9itKc8YQ
— Gavin Schmidt (@ClimateOfGavin) May 31, 2023 -
The conventional wisdom pays attention to the ENSO forecasts collated at IRI, which come in two flavors, dynamical and statistical. https://t.co/3DLUs19bBY pic.twitter.com/DOvinuLR2K
— Gavin Schmidt (@ClimateOfGavin) May 31, 2023 -
The initialized dynamical forecasts project a very strong El Niño in the fall/winter this year (Nino3.4 > 1.5). However, the statistical models are far less bullish (predicting Nino3.4 < 0.5). The consensus forecast splits the difference more or less. But that's a big spread!
— Gavin Schmidt (@ClimateOfGavin) May 31, 2023 -
There is another method tho - w/a similar level of skill - the analog method using existing climate model simulations! The idea is to look over hundreds of yrs of simulation & pick out the years that look most like today, & predict using the average of what happens in those runs.
— Gavin Schmidt (@ClimateOfGavin) May 31, 2023 -
No initialization shock, no climate model drift, and no new model runs. Almost too good to be true!
— Gavin Schmidt (@ClimateOfGavin) May 31, 2023
(the method is described in Ding et al, 2019; https://t.co/z7FQPvc4Ks). -
And what does this method suggest? Basically, it looks like Nino3.4 ~ 1 by the end of the year. An El Niño event, but nothing huge. https://t.co/TdtQzozTvh pic.twitter.com/gHCmIo1Dzj
— Gavin Schmidt (@ClimateOfGavin) May 31, 2023 -
I quite like the analog method (for basically aesthetic reasons), but while it doesn't have quite the track record as IRI, it should serve as a note of caution to those predicting Thermageddon next year.
— Gavin Schmidt (@ClimateOfGavin) May 31, 2023 -
For reference, a Nino3.4 index of 1 (statistically) in the NH winter is associated with 0.06ºC extra in GISTEMP in the year following. Enough for a bump, and maybe a record, but not an imminent breaching of the 1.5ºC level
— Gavin Schmidt (@ClimateOfGavin) May 31, 2023