Tree rings and corals both put the biggest modern El Niños at or near the top of the past millennium, and this year’s event is on track to land well above them.
Your analyses - the detail we can learn from tree rings and coral! - are great!
I expect, though, that many readers may think that even well-documented differences between 2 degrees and 3 or 4 may be nit-picking.
I suggest you tell readers - and remind them often even if you've done it sometime in the past - that the last ice age 20,000 yrs ago was just 6 degrees cooler than now, and that these small-sounding numbers have big consequences including, then, sea levels 400 feet lower than today.
If this is indeed the strongest El Nino in a thousand years (and I find your evidence convincing on that point), I see a few possible drivers:
1) natural variability. Some year has to have the strongest El Nino, and it just happened to be this one.
2) GHG-induced warming is juicing El Ninos
3) Our estimation of El Ninos is influenced by warming (I think you will understand how this is different from #2 even if I can't put it into words in the right way)
4) something other influence (maybe rapid decreases in shipping aerosols?)
Do you see any evidence favoring one of these explanations over the others?
Natural variability definitely played a big role in this event, but both of the recent millennial paleoclimate reconstructions I've highlighted here make the case that recent El Nino events in general have been on the high end of what we've experienced historically, suggesting something may have changed. Climate models remain mixed on whether or not we expect stronger El Ninos in a warming world (normalizing the index to remove long-term warming effects), so I'd avoid overconfidence in the link while acknowledging it may be there.
On your third point there is some debate about how to best measure El Nino and remove human influences. As I note in the piece the odds of an unprecedented event over the last millennium are smaller in NOAA's new relative Oceanic Nino Index, though RONI also is known to overly penalize large El Nino events like this year's that spread outside the normal Nino3.4 region (e.g. this event is strongly east-dominated and accompanied by record warmth throughout the tropics).
I'd say there is less of a link to other recent changes like aerosols (or at least I haven't seen anything in the literature suggesting such).
So we don't really know; there is a lot more interesting research to do here!
Try to remember that El Niño events are only one-third of the equatorial Pacific ENSO. and are controlled by the Trade Winds. It should make a difference. The warm 1997 El Niño was rapidly followed by a strong La Niña cooling in 1998. That's when temperatures were setting records. Not during the El Niño.
Dear Zeke, GPT 5.2 and I are having an argument about how much warming you anticipate by 2050. I thought I remembered your expectation to be somewhere around 1.7 degrees C. Am I wrong about that?
Will this el nino ratchet up the future El Ninos? Why aren't they called Los Ninos?Seems the extra heat released by it will further erode carbon sinks and the next El Ninos will follow suit. Is the new La Nina the old El Nino?
Great stuff Zeke, as always. Thank you
Excellent, easy to read analysis.
A great explanation. Thank you. I will use it in any conversations that I have about what's happening.
Your analyses - the detail we can learn from tree rings and coral! - are great!
I expect, though, that many readers may think that even well-documented differences between 2 degrees and 3 or 4 may be nit-picking.
I suggest you tell readers - and remind them often even if you've done it sometime in the past - that the last ice age 20,000 yrs ago was just 6 degrees cooler than now, and that these small-sounding numbers have big consequences including, then, sea levels 400 feet lower than today.
David Ransohoff
David.ransohoff@gmail.com
If this is indeed the strongest El Nino in a thousand years (and I find your evidence convincing on that point), I see a few possible drivers:
1) natural variability. Some year has to have the strongest El Nino, and it just happened to be this one.
2) GHG-induced warming is juicing El Ninos
3) Our estimation of El Ninos is influenced by warming (I think you will understand how this is different from #2 even if I can't put it into words in the right way)
4) something other influence (maybe rapid decreases in shipping aerosols?)
Do you see any evidence favoring one of these explanations over the others?
Thanks for all your great analyses, -Marcus
Natural variability definitely played a big role in this event, but both of the recent millennial paleoclimate reconstructions I've highlighted here make the case that recent El Nino events in general have been on the high end of what we've experienced historically, suggesting something may have changed. Climate models remain mixed on whether or not we expect stronger El Ninos in a warming world (normalizing the index to remove long-term warming effects), so I'd avoid overconfidence in the link while acknowledging it may be there.
On your third point there is some debate about how to best measure El Nino and remove human influences. As I note in the piece the odds of an unprecedented event over the last millennium are smaller in NOAA's new relative Oceanic Nino Index, though RONI also is known to overly penalize large El Nino events like this year's that spread outside the normal Nino3.4 region (e.g. this event is strongly east-dominated and accompanied by record warmth throughout the tropics).
I'd say there is less of a link to other recent changes like aerosols (or at least I haven't seen anything in the literature suggesting such).
So we don't really know; there is a lot more interesting research to do here!
Thanks - that all makes sense!
Try to remember that El Niño events are only one-third of the equatorial Pacific ENSO. and are controlled by the Trade Winds. It should make a difference. The warm 1997 El Niño was rapidly followed by a strong La Niña cooling in 1998. That's when temperatures were setting records. Not during the El Niño.
Zeke... have you tried fitting the monthly NINO 3.4 temperature anomaly against the monthly Mauna Loa CO2? in ppm?
There is no meaningful correlation.
Dear Zeke, GPT 5.2 and I are having an argument about how much warming you anticipate by 2050. I thought I remembered your expectation to be somewhere around 1.7 degrees C. Am I wrong about that?
Will this el nino ratchet up the future El Ninos? Why aren't they called Los Ninos?Seems the extra heat released by it will further erode carbon sinks and the next El Ninos will follow suit. Is the new La Nina the old El Nino?