There is a new El Niño out there and it was officially declared already on June 11 by NOAA. This is both unusually early in the year and very soon since the last El Niño in 2023-24. Another remarkable thing is the seasonal forecasts, which for a couple of months have indicated that it may well be at strengths by the end of the year that we have not seen before. All these three aspects combined seem to make this El Niño different to the previous ones.
One question is whether such El Niño events, which is a phase of the El Niño Southern Oscillation (ENSO) phenomenon, is changing because of global warming.
ENSO is a natural phenomenon, but so is also the greenhouse effect. We know that exploitation of fossil resources releases greenhouse gases, such as CO2 and methane, which strengthen the greenhouse effect. This is well-established knowledge.
The first time I was confronted with the question whether global warming also may affect ENSO was back in the 1990s, when I did my D.Phil. on mechanisms responsible for ENSO dynamics.
It was also the time seasonal forecasting was established at the European Centre for Medium Range Forecasting (ECMWF), and it was very much focused on ENSO. Since then, the seasonal forecasts for ENSO have made impressive progress and are now quite accurate (see the graphic above).
One indicator central for ENSO is NINO3.4 which provides a measure of how much the average sea surface temperature (SST) over the region 5°S-5°N/120°W-170°W deviates from normal conditions. The latest seasonal forecasts for NINO3.4 are shown in the graphics above.
Jacob Bjerknes was a pioneer on ENSO and the first to realise that El Niño events were coupled with changes in the atmosphere, the Southern Oscillation. Since ENSO indeed involves a coupling between the ocean and the atmosphere, there are several ways that global warming plausibly may affect how ENSO behaves.
The mechanisms that drive the ENSO dynamics include cloud formation, how winds respond to temperature changes, and how Rossby and Kelvin waves propagate in the ocean. In my D.Phil thesis from 1997, I found that the propagation Kelvin waves is affected by changes in the temperature structure. There have been many studies since then, and different global climate model studies (GCMs) have pointed in different directions.
One problem is that the GCMs may not have had detailed descriptions of small-scale parts of the system with sufficiency accuracy to give a robust result, and a quote from the Intergovernmental Panel on Climate Change, assessment report 6 by working group 1 (IPCC AR6 WG1) sums it up:
CMIP6 models are able to reproduce most aspects of the spatial structure and variance of the El Niño–Southern Oscillation (ENSO) and Indian Ocean Basin and Dipole modes of variability (medium confidence). However, despite a slight improvement in CMIP6, some underlying processes are still poorly represented.
In this case, CMIP6 refers to the World Climate Research Programme’s (WCRP) Coupled Model Intercomparison Project phase 6. While the IPCC AR6 WG1 concludes that
There is no consensus from models for a systematic change in amplitude of ENSO sea surface temperature (SST) variability over the 21st century in any of the SSP scenarios assessed,
I still think that this question is not resolved, since there are also studies suggesting that the models indicate that a global warming may result in stronger El Nino events, e.g. Cai et al., (2014) and Fredriksen et al., (2020).
References
- W. Cai, S. Borlace, M. Lengaigne, P. van Rensch, M. Collins, G. Vecchi, A. Timmermann, A. Santoso, M.J. McPhaden, L. Wu, M.H. England, G. Wang, E. Guilyardi, and F. Jin, "Increasing frequency of extreme El Niño events due to greenhouse warming", Nature Climate Change, vol. 4, pp. 111-116, 2014. http://dx.doi.org/10.1038/nclimate2100
- H. Fredriksen, J. Berner, A.C. Subramanian, and A. Capotondi, "How Does El Niño–Southern Oscillation Change Under Global Warming—A First Look at CMIP6", Geophysical Research Letters, vol. 47, 2020. http://dx.doi.org/10.1029/2020GL090640
Here’s the link to the 6 July NOAA CPC update (the ENSO Diagnostic Discussion update is scheduled to post Thursday, 9 July–the link is in the PDF document):
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf
Already, data suggest that El Nino conditions may persist “into” March, though later assessments may well show that conditions persist “through” March, if not into April or beyond.
–and here, the link to the NOAA CPC ENSO Diagnostic Discussion for 9 July 2026:
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.pdf
El Nino conditions remaining “through March 2027” (if not into or through April) now look possible or likely.
Thank you for this. I read that this El Nino was different. I was not sure exactly why, but at the summary at the top of the post, unusually short time since the last, an earlier start in the year, and predicted to be stronger than ever, answered that for me.
“I still think that this question is not resolved, since there are also studies suggesting that the models indicate that a global warming may result in stronger El Nino events” I also wondered about how global warming could change or currently is changing El Nino, but sometimes the most interesting answer is we don’t know yet.
thank you, Rasmus, for spelling out what is going on.
Mike
March 2026
https://jimehansen.substack.com/p/super-el-nino-super-warming-is-the
June 2026 Yes, 2026 is on Track to be the Hottest Year https://jimehansen.substack.com/p/yes-2026-is-on-track-to-be-the-hottest
Video https://dai.ly/xah8dwu
Hansen apparently says: “Multiple data sources now indicate that climate sensitivity is 4-5°C, which is consistent with aerosol-cloud modeling that reveals increasing aerosol cooling during the 1970-2005 period of rapid linear warming because of increased global spread of the aerosol sources.”
But scientists have said the period of flat temperatures in the middle of last century (about 1945 – 1975) ended mostly because of REDUCTIONS in total volume of aerosols after the 1970s, because coal power stations scrubbed most of these aerosols.
So we have two very inconsistent claims about the volume of aerosols after 1970. So as a layperson I ask whats going on?
Is it possible that aerosol volumes decreased enough from around 1970 to say about 1990 to allow surface warming to resume in full but around 1990 total aerosol volume increased again thus masking some warming? This would suggest Hansens claims of very high climate sensitivity might be too high. although perhaps still higher then 3.0 deg c. Alternatively, something is very wrong with the accepted wisdom about the flat period of temperatures last century and why it ended.
I’m definitely not a climate change sceptic. I think we are causing dangerous climate change even with medium climate sensitivity. Just curious about what seems like a significant inconsistency.
Nigelj,
This 2025 Zeke Hausfather Explainer ‘How human-caused aerosols are ‘masking’ global warming shows graphics of aerosol load by year peaking 2000-10. What happened back in 1970 was the rate of increase of the aerosol load peaked in the 1970s while the rate of additional GHG climate forcing continued ramping up. The graphic HERE is the source of the one in the Zeke Hausfather Explainer (which itself is too interactive to link-to).
Thanks. Good explanation. I must have misread something about aerosol trends, or it was incorrect.
Rasmus… “One question is whether such El Niño events, which is a phase of the El Niño Southern Oscillation (ENSO) phenomenon, is changing because of global warming. ENSO is a natural phenomenon, but so is also the greenhouse effect. We know that exploitation of fossil resources releases greenhouse gases, such as CO2 and methane, which strengthen the greenhouse effect. This is well-established knowledge.”
If one plots the monthly NINO 3.4 index against the monthly Mauna Loa CO2 going back to 1982 there is no correlation. A positive correlation exists with El-Nino and CO2 and a negative one with La Niña. But none with all three.
Ken Towe: If one plots the monthly NINO 3.4 index against the monthly Mauna Loa CO2 going back to 1982 there is no correlation.
Weather is not climate, Mr. Towe. CO2 affects global climate (timescale of DECADES) so why would you expect correlation at a local MONTHLY scale ???
In other words, garbage (wrong time-scale) in – Ken Towe’s conclusions out.
By your logic, I could disprove anything. For instance – the seasons:
– “ I found no correlation between the temperature measured twice daily and the day of spring.
Therefore, I have proven that there no such a thing as “spring”. ”
(The trick here was to drown the gradual 3-month spring warming SIGNAL – with the much wider short-term NOISE of the day-to-night differences)
As the Greeks would have said.:
“ Let the denier choose the time-scale, and he can prove ANYTHING “
Can you please clarify whether the approximately 4C. projection for the SST anomaly in the 2nd chart is global or specific to the equatorial Pacific? Many thanks.
It is for NINO3.4 which is a limited region: 120W-170W/5S-5N. Also, this is a forecast, not a projection. The nmodel starts with todays statecof the climate.
The Nino 3.4 is the most commonly used index for projections and forecasts..
Rasmus…The Nino 3.4 is the most commonly used index for ENSO projections and forecasts..
– B Tokar : “ 4C. projection for the SST”
– Rasmus: “ this is a forecast, not a projection”
Ken Towe “ The Nino 3.4 is the most commonly used index for projections and forecasts..” half a day later again: “Rasmus…The Nino 3.4 is the most commonly used index for ENSO projections and forecasts..”
And your two posts, Ken, are supposed to correct rasmuses point that the +4C is a forecast nor a projection – how exactly?
As a beginner, is this 4 c projection above normal El Nino or normal SSTs? I’m presuming the latter
What I have not seen addressed, unless I missed in, is that almost the entire North Pacific is very warm. The atmosphere will of course feel this. As such, it strikes me that “typical” el-Nino responses such as a strengthened and eastward extended subtropical jet, might not be in the offing. Other factors are at work.
But isn’t the ENSO subject to the vagaries of the Trade Winds?
Duh.
“But isn’t the ENSO subject to the vagaries of the Trade Winds?”
No. That’s a common misconception as the shift in the winds is a result of ENSO change. The ENSO dipole creates a large temperature differential across the Pacific, and that gives rise to a substantial atmospheric pressure differential. Since wind goes from high pressure to low pressure, that is the shift in winds that are being measured.
P. Pukite: “That’s a common misconception as the shift in the winds is a result of ENSO change. The ENSO dipole creates a large temperature differential across the Pacific and that gives rise to a substantial atmospheric pressure differential.” [thus driving winds – P]
Yes, but winds created by this temperature differential – weaken equatorial upwelling or even reverse it into a downwelling – which means … less cold deep water making it to the surface -> FURTHER increase in temperature in eq. East Pac. and colder water in eq. W. Pacific -> which then drives even stronger winds from W to E, and so on and on and on.
So you replaced one common misconception (“it’s the wind”) with … another misconception (*it’s the temperature”) – while in reality it is a positive feedback loop between temps and wind,
“Since wind goes from high pressure to low pressure, that is the shift in winds that are being measured.”
That is not always the case on a rotating planet. Also depends on latitude and altitude.
Dan Hughes: “That is not always the case on a rotating planet.”
Except we are discussing El Nino – which depends on what happens near the equator, where the Coriolis deflection drops to zero. So Paul Pukite’s “ from high pressure to low pressure ” is a good approximation of ENSO equatorial winds.
In more detail:
– during normal and La Nina years it blows from hot W to colder E (i.e. Walker circulation),
these practically undeflected E-> W winds – drag along warm surface water from E Pac. to West Pacific, and create eq. upwelling – bringing the cold deep water to the surface, thus further increasing the temp difference between E and W, and thus fueling even stronger E->W winds.
– during El Nino – the temp difference weakens/reverses, so the wind weakens/or reverses, the hot water blob in the West starts flow east and on to of that upwelling responsible for cold waters in the East – weakens or reverses into a downwelling (keep the cold deep water away), and with the W several deg. cooler and the E several degrees warmer the wind reversal gets reinforced.
Colder waters in the W means less evaporation which together with the shift in the direction of the winds means => less rain/weaker monsoons in the north/east Australia and South East Asia, while much warmer waters in the E and moisture-laden winds from the Pacific – brings more heavy rains, flooding, and landslides to the western coasts of S. America.
The predictable response has been given by Piotr.
Each term in the component momentum balance equations has a potential to change the mean motion. Along the line for the equator, the Coriolis effect is zero. That info is of little practical use, because we are seldom, if ever, interested in the motions of a line which contain no mass. Both North and South of the equator a Coriolis force is present and acts to change the motion in opposite directions. Generally, the focus is on regions of the atmosphere within which the Coriolis force might be both zero and non-zero.
In the present case, consideration of effects of other momentum terms on the direction of mean motion should be taken into account. It might be an improved approach to simply and explicitly state an assumption about mean motion direction, Easterlies or Westerlies, and check that assumption by data, or other methods.
Evidence of existence of potential, Easterly or Westerly mean motions, is not evidence of existence of outcome.
The default assumption, the Coriolis force can be ignored, is based on sound theoretical basis so long as the equator latitude line is of interest. The assumption implicitly contains additional assumptions about all other terms in the component momentum balance equations, and these should be stated.
A bigger issue, is to use a methodology that is based on an absence of the force in situations for which the conditions at the equator do not obtain. Application of a methodology that has absence of the force implicitly included cannot be justified.
Dan Hughes 18 Jul “ The predictable response has been given by Piotr. ”
The disappointing response has been given by Dan Hughes.
D. Hughes: “ Along the line for the equator, the Coriolis effect is zero. That info is of little practical use, because we are seldom, if ever, interested in the motions of a line which contain no mass.”
That’s your strawman, Mr. Hughes. since nobody here, other than you, was talking about
“the motions of a line which contain no mass.”
D. Hughes: “ both North and South of the equator a Coriolis force is present ”
Thank you, Captain Obvious, but you missed the point – it’s not about “presence” but about strength/significance . In the 0-2 deg. zone – the Coriolis deflection is between 0 and 3.5% of the maximum value, That’s why the trades approaching the equator do not curve as much as winds at higher latitudes, and why the resulting Walker circulation surface winds blow in approximately straight direction along the equator from high pressure toward low pressure.
So while Coriolis is very important to the winds in higher latitudes – in the area of discussion here – near the equator – its effect is at its weakest. Hence my contested by you conclusion:
P. 13 Jul: ” So Paul Pukite’s “ from high pressure to low pressure ” is a good approximation of ENSO equatorial winds.”)
Hint – the phrase “good approximation” does not demand the Coriolis deflection to be zero – it is enough that it is relatively weak (here between 0 and 3.5% of its maximum value).
Dan H. “ The default assumption, the Coriolis force can be ignored, is based on sound theoretical basis so long as the equator latitude line is of interest .”
Since I already made it clear that IT IS of interest here:
P, 13 Jul: “ we are discussing El Nino – which depends on what happens near the equator, ”
– what was the reason for your patronizing tirade?
Zeke Hausfather just posted “The Strongest El Nino Ever” on his and Andy Dessler’s Substack, https://www.theclimatebrink.com/. In answer to another reader’s question, Kevin Trenberth offered a lucid, concise explanation of how ENSO moves heat around the globe. I then asked him:
“Are the trade winds being altered as the excess greenhouse warming circulates around the globe?Zeke Hausfather just posted “The Strongest El Nino Ever” on his and Andy Dessler’s Substack, https://www.theclimatebrink.com/. In answer to another reader’s question, Dr. Trenberth offered a lucid, concise explanation of how ENSO moves heat around the globe. I then asked him:
“Are the trade winds being altered as the excess greenhouse warming circulates around the globe? Shifting latitudes as the Hadley cells expand poleward, perhaps?”
He blessed me with another generous response: https://www.theclimatebrink.com/p/the-strongest-el-nino-ever/comment/294670174. The short answer is, yes and yes!
Drat. Too much copy-pasta! Beware over-editing.
Kevin Trenberth – The wider expanse of subsiding air into the subtropics increases sunshine and heating and is a positive feedback. Hansen and others have blamed this on changes in aerosols, but it is much more from changes in clouds and circulation.
Why to they such basic facts wring, and how can you then trust them with anything else? Did Trenberth even read what Hansen was writing imn 2023 onwards about aerosols and the feedback and everything else driving the rapid warming? Or is it easier to just listen to what say and make it up as he goes because Hansen is deemed an radical outsider now?
The proof is here https://jimehansen.substack.com/ and https://www.columbia.edu/~jeh1/ and in his published peer-reviewed research papers.
Is your Zeke the same Zeke who while drawing attention often to Hansen as if it’s an obsession of his, said this last March?
writing: “My central estimate of 1.57C is a bit lower than Hansen’s 1.7C, in part because I’m assuming a moderately strong El Nino and somewhat lower warming rates (0.27C/decade in Forster et al) then the 0.31C/decade that Hansen assumes. But his estimates remain within my (admittedly large) prediction error bars.”
https://www.theclimatebrink.com/p/my-2026-and-2027-global-temperature
As opposed that is to Hansen was saying this about the same time:
“The 300 m temperature already assures that we will have an El Nino in 2026-27. The March average of the 300 m temperature anomaly exceeds +1°C. At that point, it is consistent with either a Super El Nino (Fig. 2a) or an ordinary El Nino (Fig. 2b). However, in the first week of April, the 300 m anomaly reaches +1.6°C (Fig. 3). This increasing heat anomaly is a result of the reinforcing Kelvin wave (Fig. 4, left) traveling from west to east (see the discussion in our prior El Nino post[4]). This Kelvin wave was boosted by recent westerly wind anomalies (Fig. 4, right).
We will update these figures on our website[1] at weekly and monthly intervals until the magnitude of the El Nino is clear. ” April 15
https://jimehansen.substack.com/p/super-duper-el-nino
and before that
https://jimehansen.substack.com/p/runaway-climate-the-point-of-no-return and
https://jimehansen.substack.com/p/super-el-nino-super-warming-is-the
and here in 2025!!!
https://jimehansen.substack.com/p/global-temperature-in-2025-2026-2027
Then there is the published peer reviewed papers:
See Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed?
Fingerprinting the Climate Acceleration Mechanisms and
Reconciling Our Analysis and Aerosol Models
“The main conclusion is that modern temperature change does not provide a tight constraint on climate sensitivity because aerosol forcing is not measured; however, if aerosol forcing is nonlinear (as in Aerosols A and B), IPCC (and thus most of the scientific community) has underestimated climate sensitivity.”
and
“This difficulty has led to consternation that “something is wrong.” In contrast, Aerosols A and B scenarios, with their associated climate sensitivities (∼4.5 and 6 °C for 2 × CO2), the ship aerosol forcing, and a +0.2 °C El Niño, readily reach +1.6 °C current warming.”
and
“Climate feedbacks are real; paleoclimate evidence shows that “fast” feedbacks (water vapor, clouds, and sea ice) amplify climate sensitivity from 1.2 °CFootnote91 for doubled CO2 with no feedbacks to as much as 4-5 °C, i.e., these well-known feedbacks more than triple the equilibrium climate response. ”
https://www.tandfonline.com/doi/full/10.1080/00139157.2025.2434494#abstract
Then there is the Global warming in the pipeline paper which Trenberth may not have read (?)
. However, decline of aerosol emissions since 2010 should increase the 1970–2010 global warming rate of 0.18°C per decade to a post-2010 rate of at least 0.27°C per decade. Thus, under the present geopolitical approach to GHG emissions, global warming will exceed 1.5°C in the 2020s and 2°C before 2050.
The Johnny Come Lately cohort are a dime a dozen.
Like Zeke Hausfather, again showing up a day late and dollar short.
Another data point underpinning my conclusions of abject unreliability of ZH AD KT et al as credible sources on Climate trajectories, present drivers of acceleration and ongoing warming growth toward multiple tipping points of no return:
Q. So, why is it so strong? Just normal variability, or does climate change affect El Niño intensity?
Zeke Hausfather
A. Its a bit unclear if climate change is making strong El Nino events more likely (normalizing for long-term warming). It is strongly debated on the literature with no clear consensus.
For several years now this equals continually minimizing the state of the climate system, minimizing current trajectories and simultaneously not knowing what is happening nor why it is so.
Meanwhile the greater “controlling consensus cabal” have been incapable of defining the extent of and the cause of the 2023-24 massive and sudden temperature anomaly spike as another one approaches at pace.
While they continue to dismiss, ignore and minimize other findings such as F&R’s +0.33 C acceleration rate kicking the can down the road by hiding behind whatever the CMIP7 might produce.
Modelling the Map is not equate to Reality. Especially when the questionable processes and output is decade late.
What about the deep ocean warming, in models it shows distinct patterns and ENSO modulation. Looking forward to read more about this.
Deep ocean warming-induced El Niño changes
Ai: Plausible is an indirect, long-term influence through the global climate “mean state”: changes to ocean stratification/thermocline and deep-ocean heat uptake can alter how efficiently equatorial Pacific feedbacks grow, which changes ENSO characteristics. For example, modeling work shows that deep-ocean warming can intensify/alter El Niño variability via subsurface stratification and feedback changes in the Pacific.
Very interesting indeed. To me it seems obvious, that you would expect a strengthening of El Niño events – sooner or later – from a growing heat content in the upper layers of most of all oceans, but that is probably too simple. Maybe you could as well expect a kind of weakening or slowing down of this very complex oscillating system (interconnected with others) as a result of weakening temperature contrasts in different parts of the oceans? Though I would suspect this effect to be more long-term, happening after the earth climate system crossing several tipping points, some of which maybe even hitherto unknown or unnoticed by science. I wonder what paleoclimatology has to say on the subject of ENSO during warmer climates as fx. during the warmest period of the last interglacial, Eem, when the main sea level was 6-9 meters above the current, probably caused by the deglaciation of West Antarctica (since the Greenland Ice sheet was intact from N to S, even if somewhat reduced) or in earlier warmer climates?
The answers seem inconclusive: 1) “Future increase in extreme El Niño supported by past glacial changes” – https://www.nature.com/articles/s41586-024-07984-y (Eem) points to a strengthening of ENSO based on models, and a weakening during glacials: “Here we uncover a mechanism using numerical simulations that drives consistent changes in response to past and future forcings, allowing model validation against palaeoclimate data. The simulated mechanism is consistent with the dynamics of observed extreme El Niño events, which develop when western Pacific warm pool waters expand rapidly eastwards because of strongly coupled ocean currents and winds6,7. These coupled interactions weaken under glacial conditions because of a deeper mixed layer driven by a stronger Walker circulation. The resulting decrease in ENSO variability and extreme El Niño occurrence is supported by a series of tropical Pacific palaeoceanographic records showing reduced glacial temperature variability within key ENSO-sensitive oceanic regions, including new data from the central equatorial Pacific. The model–data agreement on past variability, together with the consistent mechanism across climatic states, supports the prediction of a shallower mixed layer and weaker Walker circulation driving more frequent extreme El Niño genesis under greenhouse warming.”
Note that the eemian warming wasn’t caused by higher CO2 levels in the troposphere, they were never above 280 ppmv.. Nor any known changes in aearosols etc. Methane levels were much lower than current https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GB007875 . This article (1) doesn’t consider these themes, since they only study the last glacial maximum, 21 kyr BP.
2) “Mid-Pliocene El Niño/Southern Oscillation suppressed by Pacific intertropical convergence zone shift” https://www.nature.com/articles/s41561-022-00999-y?fromPaywallRec=false . This article seems (I have only read the abstract) not to consider that a) at this time was the Panaman isthmus maybe still (partly) open and hence b) the AMOC not yet established. The Greenland ice sheet was just beginning to form, bottom layers of icecores suggest a deglaciated Greenland then.
We can still only conclude that “we are in uncharted waters” as Gavin Schmidt said in 2023 when the currently ongoing acceleration in global warming came up first. Or? Can we get beyond the rather obscure and unimportant deliberations/ditherings about less than one tenth of a degree C in global mean up or down next year? Much more fateful things are at stake for billions of people: the consequences in ten years, crossing the two-degree C limit and very fast moving further up. As prognosticized by Rahmstorf and Foster recently https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2025GL118804 .
I cenrtainly hope that the critique by James Hansen here “Our scientific papers[5],[6] evoked a strange response from several scientists who serve as public faces of the modeling community: ad hominem criticisms, but no response to the scientific issues that we raised. We have called out[7] this odd response to draw attention to failure of the media to provide quality science reporting on climate change. Given the enormous implications of climate change for the public, especially young people, it is incumbent on the media to ask questions of scientists and demand understandable scientific explanation of their conclusions”
https://jimehansen.substack.com/p/yes-2026-is-on-track-to-be-the-hottest – can soon be cleared up here on realclimate. Which “strange” and “ad hominem” responses does Hansen implicate? Can someone enlighten us? What is the real scientific issue at hand (if there is one, which to me seems to be the case)?
My main observation is this: the current man-made raising ot the tropospheric CO2 and methane levels has no known natural precursors in the whole history of about 3 billion years of life on this planet. Not even close! The CO2 emissions in the end permian 251,9 myrs ago were larger than ours for sure, but they took over 75000 years! We are going far faster than that. That’s certainly no reason to relax and think “we just need to adapt a little” which is now becomiing the mainstream political and “scientific” (bureaucratic) message from people who are adapting – but unfortunately more to fascism 2.0, model Trump and Musk, Putin etc. than to the rising resistance.
KVJ..You may have missed this?
Nature 461, 1110-1113 (22 October 2009)
Atmospheric carbon dioxide through the Eocene–Oligocene climate transition
Paul N. Pearson, Gavin L. Foster, Bridget S. Wade
Geological and geochemical evidence indicates that the Antarctic ice sheet formed during the Eocene–Oligocene transition 33.5–34.0 million years ago. Modelling studies suggest that such ice-sheet formation might have been triggered when atmospheric carbon dioxide levels fell below a critical threshold of ~750 p.p.m.v. During maximum ice-sheet growth, pCO2 was between 450 and 1,500 p.p.m.v., with a central estimate of 760 p.p.m.v.
760 ppm is much higher than today’s value. And the Eocene plant life on land was lush while the carbonate plankton thrived..
KT: 760 ppm is much higher than today’s value. And the Eocene plant life on land was lush while the carbonate plankton thrived..
BPL: But during the Eocene, there were not 8 billion people depending on a stable climate for their agriculture; nor were there trillions of dollars worth of coastal infrastructure in danger of submergence.
EarthClimate: “As reported in the previous study, the deep ocean acts as a stove, continuously supplying heat to the ocean surface”
in the high latitudes. NOT at the discussed here equator/ the ITCZ. Here, the deep ocean is much colder than the surface water. That’s why the ocean off Peru is not the best place to go for a vacation swim – despite being in the tropics, the surface water the water is typically 16-20C – because of the cold Humboldt current and the upwelling bringing very cold deep water to the surface. To swim there you have to time your visit to the El Nino, which disrupts Humboldt current and blocks the upwelling, which increases the surface water temps by 4-8C.
So for this region – deep ocean is not “a stove”, but a cooler.
Emergent climate change patterns originating from deep ocean warming in climate mitigation scenarios
“EarthClimate” 14 Jul 7.47am: “AI: The eastern Pacific refers to the eastern portion of the Pacific Ocean,”
Thank you, Captain Obvious, without you quoting AI on that we would have no idea.
Now the harder part – prove YOUR claim that the “deep ocean” in this equatorial eastern Pacific – “acts like a stove, continuously supplying heat to the ocean surface,”
Let me help you with your authority:
AI: “The deep water temperature in the eastern equatorial Pacific typically ranges from 1C to 4C”
and
AI: “Sea surface temperatures in the eastern equatorial Pacific currently range from 28C to 29C”.
And if suddenly stopped believing AI: let your own eyes be the judge – here is a vertical profile of T from NOAA. Unfortunately it is truncated at mere 500m (ocean there is typically >4km deep), but even this gives you a good idea what is hotter – “the surface waters” or the “deep ocean”:
https://www.ncei.noaa.gov/monitoring-content/sotc/enso/2004/may/dep-lon-200405-eq-0-500-pg.gif
“Deep ocean there acts like a stove, continuously supplying heat to the ocean surface, you say?
Explained here, starting 7 minutes in https://www.youtube.com/watch?v=Mqtt8Ln35t4
Notice that talk about deep ocean should also point to origin to put this in better perspective.
In Re to Piotr, 15 Jul 2026 at 7:47 PM,
https://www.realclimate.org/index.php/archives/2026/07/this-new-el-nino-is-different/#comment-849797
Hello Piotr,
I parsed through the cited article and have not identified a specific part thereof that might form a basis for the conclusion in the abstract that you have objected.
It seems to be indeed unclear how the authors of the article arrived at the conclusion that the heat stored in the deep sea can warm not only polar regions and/or sea regions wherein the sea surface temperature falls below the deep sea water temperature at least during winter seasons, but also the equatorial eastern Pacific.
If “EarthClimate” found this basis, I would highly appreciate their hint thereto.
Greetings
Tomáš
Mr. E. Climate: ” Explained here, starting 7 minutes in https://www.youtube.com/watch?v=Mqtt… ”
a link to a clip on Youtube proves nothing – I am sure that there are clips that starting x minutes in – show the the Earth is flat. Does not make it magically so. So if you have anything to say – say it in your own words. Here by:
1. proving the claim that in equatorial eastern Pacific “the deep ocean acts as a stove, continuously supplying heat to the ocean surface”
2. disproving the oceanographic knowledge from the last 100+ years that the opposite is true (the deep ocean there is much colder than the surface water and therefore can NOT act as a stove, but only as cooler)
3. disproving the vertical profiles of temperature from the literature I have referred to – that show the same as p.2 and thus challenge your stove claim) – namely: I have posted – which shows T at 500m is ~ 9C while the surface water shows at least 25C.
In case if the arithmetic wasn’t your strongest suit, 25> 9,. Thus you can’t HEAT 25C water by an upwelling of 9C water. Consequently, the deep water there can NOT “act as stove” to surface water, but only as its cooler.
Now, to maintain any pretense of your intellectual integrity – you have to succeed in all three points. But you can’t in ANY of the 3. Which means that you promote fruits of your staggering oceanographic and climatic ignorance. Ironic for somebody who chose such an ambitious handle as: “Earth Climate”. That’s as if somebody with IQ 50 – chose the handle “Genius”.
in Re to EarthClimate, 16 Jul 2026 at 8:53 AM,
https://www.realclimate.org/index.php/archives/2026/07/this-new-el-nino-is-different/#comment-849800
Dear Sir or Madam,
The video you referred to does not seem to explain the claim (that heat release from the deep ocean can warm surface layer in the equatorial eastern Pacific) from the abstract of the Ji-Hoon Oh et al article
https://www.nature.com/articles/s41558-024-01928-0
cited by you.
I think so because the video pertains to ENSO oscillations and speaks about heat accumulated in the layer above thermocline, in depths between 50 and 250 m, while the cited article speaks about the heat accumulated in the “deep ocean” and released after hypothetical decrease of CO2 radiative forcing to the level before the spike in this forcing that caused the said heat accumulation.
Can you comment?
Best regards
Tomáš
Ken Towe, I am fully aware, that Paul N. Pearson in 2013 wrote a note about these themes, entitled “When was the CO2 last above 400 ppmv?” The conclusion in this note was, that there hasn’t been a stable CO2 level above 400 ppmv for the last 26 myrs.
A scientific article from 2020 points in the same direction: Cui et al.: “A 23 m.y. record of low atmospheric CO2″, Geology (2020) 48 (9): 888–892” https://pubs.geoscienceworld.org/gsa/geology/article/48/9/888/586769/A-23-m-y-record-of-low-atmospheric-CO2 .
From the abstract: “Here, we present a new CO2 record across the past 23 m.y. of Earth history based on the δ13C value of terrestrial C3 plant remains, using a method applicable to the entire ∼400 m.y. history of C3 photosynthesis on land. Across the past 23 m.y., CO2 likely ranged between ∼230 ppmv and 350 ppmv (68% confidence interval: ∼170–540 ppm). CO2 was found to be highest during the early and middle Miocene and likely below present-day levels during the middle Pliocene (84th percentile: ∼400 ppmv). These data suggest present-day CO2 (412 ppmv) exceeds the highest levels that Earth experienced at least since the Miocene, further highlighting the present-day disruption of long-established CO2 trends within Earth’s atmosphere.”
Nonetheless the IPCC continues to postulate that today’s CO2 levels can be found not further back than 3 myrs BP, 20 myrs later than Cui et al., but what exactly they base this result upon seems unclear. As is often the case with the IPCC “consensus”, the exact sources of it seem a bit dodgy: how was the concensus established, when most scientific results point to much older datings of naturally high CO2-levels? This is of the utmost importance, since it implicates that the current high and fast rising CO2 level is a much more serious and dangerous matter than the impression you get from the IPCC reports.
It seens to me that you don’t need to be Sherlock Holmes to sense a connection between this matter and *the fact that the IPCCs COPs still after more than forty years have never been able to agree upon the evident scientific fact that we need to cut fossil fuel use very fast to avoid very dangerous climate change.* The source of the COP/IPCCs unrealisticly optimistic conclusions are obviously very powerful fossil fuel capital lobbying groups and their denialist propaganda, not science. As concluded many years ago by James Hansen, Naomi Oreskes and many others.
KVJ..You may have missed this…it wasn’t posted earlier…
Nature 461, 1110-1113 (22 October 2009)
Atmospheric carbon dioxide through the Eocene–Oligocene climate transition
Paul N. Pearson, Gavin L. Foster, Bridget S. Wade
Geological and geochemical evidence indicates that the Antarctic ice sheet formed during the Eocene–Oligocene transition 33.5–34.0 million years ago. Modelling studies suggest that such ice-sheet formation might have been triggered when atmospheric carbon dioxide levels fell below a critical threshold of ~750 p.p.m.v. During maximum ice-sheet growth, pCO2 was between 450 and 1,500 p.p.m.v., with a central estimate of 760 p.p.m.v.
760 ppm is much higher than today’s value. And the Eocene plant life on land was lush while the carbonate plankton thrived..
KVJ: The CO2 emissions in the end permian 251,9 myrs ago were larger than ours for sure, but they took over 75000 years!
KT: 760 ppm is much higher than today’s value. And the Eocene plant life on land was lush while the carbonate plankton thrived..
MA: Oh, Ken, what makes you think Karsten missed that? The Eocene-Oligocene CO2 maximum took half a million years! What’s different about the globe, and the accelerating rate of increase, today? In any case, perhaps you missed “The enigma of Oligocene climate and global surface temperature evolution” (https://www.pnas.org/doi/abs/10.1073/pnas.2003914117. From the abstract (my bolding):
In this relatively low CO2 Oligocene world (∼300 to 700 ppm), warm climates similar to those of the late Eocene continued with only brief interruptions, while the Antarctic ice sheet waxed and waned. SSTs are spatially heterogenous, but generally support late Oligocene warming coincident with declining atmospheric CO2. This Oligocene warmth, especially at high latitudes, belies a simple relationship between climate and atmospheric CO2 and/or ocean gateways, and is only partially explained by current climate models. Although the dominant climate drivers of this enigmatic Oligocene world remain unclear, our results help fill a gap in understanding past Cenozoic climates and the way long-term climate sensitivity responded to varying background climate states.
IOW, keep it as simple as you can, but no simpler: it will never convincer pseudoskeptics anyway.
KT: 760 ppm is much higher than today’s value. And the Eocene plant life on land was lush while the carbonate plankton thrived..
Except that it was a … different life. Current “lush plant life” on land is adapted to 280 ppm, not to your 760ppm. And they had 100,000s or millions of years to evolve adaptations, not a few decades or centuries. And if you haven’t noticed, 33.5–34.0 million years ago, there were no humans nor even our ancestral species.
As for the carbonate marine organisms “thriving” – those again were different than those that thrive today in lower-Co2 seawater – the higher the CO2 the much more difficult survival of the organisms making their shells from the more soluble forms of carbonates – aragonite and high-Mg calcite – this include such an unimportant taxa as pteropods and coral reef-making corals and calcareous red-algae.
Ocean acidification from increased CO2 amplifies the damage of coral reefs caused already by bleaching due to increasing frequent ocean heatwave under higher CO2. Again – if the changes were spread over geological time-scale – reef-making corals could perhaps move into colder waters, or perhaps new species evolved to replace them although most likely will be a formation of a “reef gap” – periods of millions of years without reef-making aragonite corals, replaced with the non-reef making soft corals using calcite – with the resulting loss of the single most productive and supporting the highest diversity habitat on Earth
So much for your belief that the oceanic life will be “thriving” under current Co2 increase rate.
P.S. What are you doing for living, Ken? I ask because I am trying to establish the motivation for your posting activity here: are your financially benefitting fossil fuels, or are you what Lenin called a “useful idiot of Russia” and of other petro-states, whose regimes, wealth of their oligarchs, and ability to control their population and wage wars on others – depends on convincing the world to what you, Ken, promote here – that that the world with much higher Co2 (“760 ppm of CO2”) would have a “lush plant life” and “thriving” oceans. .
I’ve seen informed comment – Michelle L’Heureux – that SST in tropical Pacific relative to extant global SST e.g. NOAA’s RONI – rather than to average (past) ENSO zone temperatures – may be a better predictor of the strength of weather effects. I’m not so informed as can offer any judgement but it seemed to make sense.
That differences in SST are a major driver of wind and weather patterns seems kinda fundamental.
This was just posted..
The Strongest El Niño Ever
A new study finds shorter ENSO frequency, and broader modulation of the climate system. Excerpts from the pre-print..
Changes in El Niño–Southern Oscillation and global frequency entrainment
“declared already on June 11 by NOAA. This is both unusually early in the year”
Of the previous 10 El Nino declarations, 4 were earlier and 6 were later.
This one does not seem particularly unusual
Useful Bookmarks
Climate Uncensored
What Path is the Real World On?
James Hansen, Pushker Kharecha, Dylan Morgan, Jasen Vest
Climate Science, Awareness and Solutions (CSAS)
DATA
https://www.columbia.edu/~jeh1/Data/
El Nino & La Nina DATA
ENSO indices, upper-ocean temperature, and their relationship to global surface temperature.
Figures on this page
1. Recent ENSO and global temperature
2. Extended ENSO indices (1950–present)
3. ENSO and global temperature relationships
4. ENSO cycle comparisons: Nino3.4 SST, RONI, and upper 300 m
5. Pacific Decadal Oscillation (PDO)
https://www.columbia.edu/~jeh1/Data/ElNino-LaNina/
“Keeping the bastards Honest” (?)
I happily accept posting this is a waste of time overall beyond a slight peace of mind benefit.
June 12
An article in the Washington Post last week reported that “climate scientists” peg the odds as 27% that 2026 will be the record warmest year. Perhaps the author was unaware of our 30 April Substack post “2026 On Track for Warmest Year” or perhaps he does not consider us to be climate scientists worth acknowledging. In any case, this year provides a chance to learn something from contrary predictions. The Washington Post article refers to a projection of Zeke Hausfather on 2 June that there is a 26.6% chance of 2026 being the warmest year.
Zeke has provided enough information to allow a contrast with our approach.
Below we describe the basis for our prediction and our principal differences with Hausfather.
Based on this scientific evidence, we expect that when the horse race comes down the stretch, in November and December of this year, we will be riding a thoroughbred, a strong young horse, and Zeke will be atop a fading old nag. In any event, we will then be able to assess whether we have learned anything that helps young people define policies to create a bright future.
1)
As we described in our recent papers,[5],[6] the most important result is that climate sensitivity is significantly higher than the long-standing best estimate of 3°C for 2×CO2, a conclusion we can state with greater than 99% certainty.
2) The albedo reduction is so large that most of it must be due to a reduction of sunlight reflected by clouds, as the contributions from reduced sea ice cover and reduced human-made atmospheric aerosols are relatively small.[6] This implies that cloud changes are a strong, amplifying, climate feedback. If cloud changes were neutral (no net warming or cooling effect), climate sensitivity would be about 2.4°C for doubled carbon dioxide because water vapor and sea ice feedbacks roughly double the no-feedback climate sensitivity of 1.2°C.
3) The fact that only a 6 percent solar irradiance change is needed to cause snowball Earth implies that climate sensitivity is high, about 4-5°C for doubled carbon dioxide, and Earth system sensitivity (including ice sheet changes neglected in Charney’s sensitivity) is even higher.[14]
4) Sulfates produced by SO2 emissions are the principal anthropogenic aerosol, but it is unlikely that global aerosol climate forcing is proportional to SO2 emissions. Aerosol scientists describe the great uncertainty in the aerosol forcing in IPCC reports. The largest uncertainty is in the effect of aerosols on cloud formation and cloud properties.
and
Independently, we show that, among the three aerosol coolings (0, 0.5, 1 W/m2), the intermediate case (implying climate sensitivity 4.5°C for 2×CO2) provides the best representation of total temperature change for 1880-present.[6]
Then — A strong El Nino is about to begin. We have shown in prior posts that the heat anomaly in the upper 300 m of the equatorial Pacific provides an El Nino diagnostic with more favorable characteristics than the common Nino3.4 SST (sea surface temperature) index. The 300 m heat provides an earlier indication of an upcoming change of tropical climate and it is less affected by human-made global warming.
For the purpose of predicting temperature in the remainder of 2026, we note in Fig. 8 that global SST in 2026 has approximately “caught” the 2024 global SST in May (upper figure) and 2026 continues to be at least 0.1°C warmer than in 2023 (the last El Nino onset year). We expect that gap to be maintained, as the upcoming El Nino is at least as strong as the one in 2023. We note also that Earth’s energy imbalance for the last 15 months of data (January 2025 through March 2026) is 1.58 W/m2, even higher than the prior decade (Fig. 4). The year 2026 should already exceed the 2024 record, with higher temperatures to come in 2027.
and
Summary: the media are gobbling up and regurgitating an interpretation of global climate change that we believe is fundamentally flawed.
We have presented extensive independent evidence that climate sensitivity is 4-5°C for doubled CO2. The implications of our interpretation are great.
A secondary issue is the climate forcing caused by decreasing emissions from ships. We have presented evidence that ships are responsible for an increase of at least a few tenths of 1 W/m2 in the past decade. At least in this case, we can make a quantitative comparison with the IPCC estimate as Forster and Hausfather calculate 0.079 W/m2.[20] Observational data, in combination with improving aerosol-cloud modeling, should be able to resolve this difference. We believe that the larger effect that we estimate for ship aerosols is at least partially responsible for the sharp uptick in Earth’s energy imbalance and temperature shown in Figs. 4, 6 and 7.
[ ie. secondary issue, partially responsible, and NOT BLAMED FOR …. as incorrectly framed by Trenberth then concluding ]
It is hard to resolve the differences of opinion on the more important issue of climate sensitivity and global warming on the century timescale because the IPCC modeling approach and how it is used by Hausfather and others for their climate projections is foggy, i.e., not well defined. It seems to be based on the fog of model results produced by all climate models.
However, the projections produced are continually changing; such is the case for 2026 global temperature. How are these determined? If we are to gain knowledge from real-world climate “experiments,” such as that occurring this year, we need to understand the basis for the predictions.
https://jimehansen.substack.com/p/yes-2026-is-on-track-to-be-the-hottest
Therefore, Trenberth’s critique is a simplification. Hansen frames the 2023-24 temperature anomaly and the prediction for 2027 as the result of a synergistic effect: an El Niño event releasing heat, amplified by the recent global reduction in aerosol cooling (especially from shipping), the overall amplification of cloud feedbacks with all operating under a higher-than-expected climate sensitivity.
Hansen notes that changes in clouds act as a powerful amplifying feedback. The reduction in global aerosols not only removes direct cooling but also alters cloud properties. Increased background global warming too alters cloud properties. Resulting in a substantial darkening of the planet (reduced albedo) since 2015 simultaneously being amplified by the higher ECS above that accepted by the IPCC. .
The projection for a record +1.7°C in 2027 is based on this integrated framework, not aerosols nor IMO reductions alone.
The ‘Acid Test’ was Hansen’s expectation that temperatures would not fall much below +1.5°C following the 2023-24 El Niño . It was a deliberate ‘acid test’ of his theory now shown to be accurate. This prediction hinged on the persistent warming from both the loss of aerosol cooling and high climate sensitivity, amplified by cloud feedbacks, which he argued would prevent the typical post-El Niño cooling, coupled with the underlying growth of warming from total global emissions and ongoing land use changes.
Kevin Trenberth’s statement that Hansen “and others have blamed this on changes in aerosols” misrepresents Hansen’s position. In both his public communications and peer-reviewed work, Hansen presents global reductions in aerosols, the more recent IMO shipping changes, as only one critical aspect of a multi-factor explanation for recent warming, for the post 2010/2015 rapid acceleration and the looming super-el nino with predicted record 2026 and 2027 global temperatures and not the sole cause.
A lot of text above, sorry, but I wanted to empathize this particular section as well.
Hansen
2) The albedo reduction is so large that most of it must be due to a reduction of sunlight reflected by clouds, as the contributions from reduced sea ice cover and reduced human-made atmospheric aerosols are relatively small.[6] This implies that cloud changes are a strong, amplifying, climate feedback.
Whereas Trenberth, courtesy of Mal Adapted above says :
Kevin Trenberth – “The wider expanse of subsiding air into the subtropics increases sunshine and heating and is a positive feedback. Hansen and others have blamed this on changes in aerosols, but it is much more from changes in clouds and circulation.”
Hansen adds:
4) Sulfates produced by SO2 emissions are the principal anthropogenic aerosol, but it is unlikely that global aerosol climate forcing is proportional to SO2 emissions. Aerosol scientists describe the great uncertainty in the aerosol forcing in IPCC reports. The largest uncertainty is in the effect of aerosols on cloud formation and cloud properties.
That analysis has nothing at all to do with the recent IMO emissions reductions of SO2 emissions. Hansen has always been addressing the larger picture and the total lack of credible data supporting the modelling communities unfounded unproven assumptions of global aerosol forcing, cloud albedo forcing and the additional amplifying climate feedbacks.
I seriously question how well informed Trenberth and Hausfather are about the research analysis by Hansen’s team and the many other independent climate scientists.
Furthermore, in Trenberth’s reply to a commenter he offers a media article reference authored by himself dated July 2023. At the beginning of the rapid warming period 2023-2024-2025 when he and everyone else barely knew anything about it or how bad it would become. Let alone the coming El Nino responses or how much higher the long term warming rate had accelerated by 2025 — overriding prior assumed “step changes”..
source https://www.theclimatebrink.com/p/the-strongest-el-nino-ever/comment/293971896
Which for me, begs the question–has Trenberth learned anything new about El Ninos, the rapid spike in warming acceleration or what may have caused the massive unexpected Bananas of 2023-2024 El Nino period since his article of July 2023?
Hansen stating shipping emission changes is partially responsible does not suddenly make them totally responsible nor blamed for all recent warming acceleration or higher anomalies. And it is not what his papers contain either.
Reading Hansen’s output accurately, understanding it fully, and the peer-reviewed papers and recent articles by others since then, might help Trenberth update his knowledge? Hausfather and others too. Reader’s are advised to recognize the difference between fading reputations and quality science.
Hansen is not acting alone. There is a small army supporting his scientific work and funding it.
Apologies for any scientific semantic errors in my phrasing above, I completely defer to Hansen and his team for accuracy. Excuse the length, my small effort at trying to correct a small part of the ongoing disinformation on this topic which I find frustrating. .
KM: I happily accept posting this is a waste of time overall beyond a slight peace of mind benefit.
MS: It was useful for me. Thank you.