El Niño has become an annual global climate phenomenon. But this year, scientists are warning of a record-setting ‘super’ El Niño. What that could mean for the weather everywhere on planet earth.

Guests

Daniel Swain, Climate Scientist with University of California Agriculture and Natural Resources.

Also Featured

Michelle Nunn, President and CEO of CARE.

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Transcript of Full Broadcast

The version of our broadcast available at the top of this page and via podcast apps is a condensed version of the full show. You can listen to the full, unedited broadcast here:

Part I

MEGHNA CHAKRABARTI: Way back in 1578, fishermen plying the waters off the coast of Peru noticed something weird. An unusually warm current in the Pacific was altering their catch. They named it El Niño, or The Child, since the warm water resurfaced every few years around Christmas. In the centuries since, scientists have come to understand how this temporary flow of warmer than usual water in the Pacific Ocean can change weather patterns around the world.

This year, El Niño is back, and it’s a big one, with waters so warm even scientists not usually given to hyperbole are calling it a super El Niño. We’ve even heard one call it a Godzilla El Niño, both of which mean potentially drastic weather and climate impacts everywhere on Earth. And here in the United States, just last week, California Governor Gavin Newsom declared a state of emergency in order to prepare California communities for the changes that El Niño might bring.

So let’s talk about why this year’s El Niño is a, quote-unquote, “super one,” and really what that means for you wherever you are on planet Earth. So Daniel Swain joins us. He’s a climate scientist with the University of California Agriculture and Natural Resources Group. He’s also a research partner at the NSF National Center for Atmospheric Research, and he joins us from Davis, California.

Daniel Swain, welcome to On Point.

DANIEL SWAIN: Thanks for having me on the show, Meghna.

CHAKRABARTI: Okay, so first of all, I have heard the phenomenon of El Niño called something akin to the Pacific Ocean kind of burping up warm water to the surface. Let’s get to the root causes. What causes that burping of warm water?

SWAIN: Yes, and I think I’ve myself used various expressions to refer to how and why the Pacific Ocean is so influential in global climate.

And during El Niño events, how it essentially becomes this discharging battery, if you will. So the oceans all around the world store a considerable amount of heat. We know that the oceans cover something like 70% of the Earth’s surface. We live, in a certain sense, on a water planet.

So when the climate is warming, for example, the oceans are doing a lot of that heat-absorbing work for us. And El Niño itself, as you mentioned, is a natural climate oscillation. It’s not caused by climate change itself, but fundamentally what it does is it releases every two to seven years or so large amounts of heat that are stored in the subsurface.

So beneath the surface of the ocean, in the deeper ocean, it emerges during El Niño events, and it does so in a specific patch of the eastern tropical Pacific Ocean, west of the Galapagos Islands. Fundamentally, that’s what El Niño is. It’s just this episodic warming of the eastern equatorial Pacific Ocean.

And when it does so, it can profoundly affect global weather patterns for months thereafter.

CHAKRABARTI: Yeah, so we’ll talk about that for the majority of the hour, but I’m kind of interested in the thermodynamics of the Pacific. How is it, what triggers this release of heat from the deep ocean?

SWAIN: We talk about El Niño as one part of a broader cycle, the El Niño Southern Oscillation, or … ENSO is the acronym. The other end of the spectrum from El Niño is La Niña. So El Niño is the warm phase. La Niña is the cool phase of the same oscillation. It goes back and forth every two to seven years or so, but the reason why it’s two to seven years is not because it regularly goes from two to seven years, but because it can be anywhere from two to seven years.

So it’s an irregular oscillation, and sometimes it takes longer than other times for a certain amount of heat to build up in the subsurface of the Tropical Pacific Ocean. And when we let more of that heat build up over longer periods, generally speaking, then there’s more heat to potentially be released in a larger El Niño event.

So generally, it would be difficult, for example, to get back-to-back strong El Niño events simply because we’ve released so much of the accumulated heat that it will take years some years for it to build back up to the same level. Now, in a warming climate, some of the heat that’s being released is heat coming from the fact that the planet is absorbing more energy, including the oceans, than it used to.

But either way, whether that accumulated heat is coming from a long-term accumulation from climate change, or whether it’s just part of the natural aspect of the cycle where this is the mechanism by which the Earth releases excess heat from the oceans into the atmosphere where it gets dissipated globally, this is an equilibration mechanism.

This is one of the ways that the climate system manages to redistribute heat from the tropical oceans and dissipate it throughout the global atmosphere.

CHAKRABARTI: Nature is beautiful, isn’t she? The idea that an entire ocean can recalibrate seeking a thermodynamic balance is just remarkable to me.

Last kind of nerdy I guess deep chemistry and physics question. Is it just that the makeup of the deeper waters in the Pacific, its salinity, et cetera, there’s a maximum amount of heat that it can hold before it has to be released? Because I’m just wondering why it doesn’t further dissipate elsewhere within the water. Like, why doesn’t it move with currents to the southern oceans or the Arctic?

SWAIN: And there are other current systems that can do that in other ocean systems, but still, it’s true that ENSO and the Tropical Pacific are a little bit special, and that’s partly because of just the fundamental geography of the Pacific Basin.

The Pacific Rim, is an enormous basin. If you include the entire North Pacific, the entire South Pacific, it’s this vast ocean. It takes up a significant fraction of the surface of the Earth to go from the West Coast of North America to Asia, and then southwest to Australia, and southeast to the South America.

And so the basin has some unique characteristics. The general state of things is there are east to west trade winds that blow in the tropics, so from South America to Indonesia, say, and that’s the usual state of things. In a La Niña event, the cool phase, those trade winds actually strengthen and you get even stronger than usual east to west winds in the tropics.

Those east to west winds actually allow the surface of the ocean itself to pile up in the West Pacific, so there’s literally a slope as much as a foot or two to the ocean surface itself between the West Pacific and the East Pacific under normal conditions. Now, it’s not usually perceptible because that’s occurring, again, it’s one or two feet vertically over thousands of miles horizontally, but it is notable from a large mass of water that’s at an angle perspective.

And during an El Niño event, what happens is these trade winds, for whatever reason, sometimes it’s truly just random, sometimes there’s a specific trigger, but it can just be random, they temporarily weaken for a while, enough that some of the water that is being held up by these, by the forces from this wind in the West Pacific literally sloshes back eastward so that gravity is the restoring force.

It wants that water to slosh back east if the ocean wind is no longer pushing it to the west, and it begins to do so. And that water in the West Pacific is much warmer than the water in the East Pacific, again, a quirk of geography, because the East Pacific is where a lot of cold water upwells, so moves upward vertically from beneath.

Long story short, this sets into motion a very complex chain of events where the water begins to slosh eastward. It’s warmer, and then eventually, if that warmer water makes it far enough east, it begins to disrupt the wind currents themselves, making the process self-perpetuating. A vicious cycle, essentially.

And so this begins to perpetuate. So once it gets underway it wants to complete the process. But how it begins in the first place is actually still an interesting scientific question. It can just be random weakening of the winds. It can be other things, but that’s usually how it gets started.

CHAKRABARTI: Okay. Thank you for explaining that, because I was always wondering what was the trigger? And I guess the long story short is that we don’t yet exactly know, but we know what happens once an El Niño is triggered. And by the way it can sometimes get confusing for folks who aren’t full-time scientists when we talk about direction, compass directions over the ocean versus in the United States.

So when you’re talking about the Eastern Pacific, that would be the West Coast of the United States, Mexico, South America, Canada. Right? Correct?

SWAIN: Yeah. And in this case, the part of the East Pacific that matters is the tropical East Pacific. Yeah. So think the Galapagos Islands, the coasts of Peru and Ecuador.

CHAKRABARTI: Okay. And by the way, that coastal upwelling zone, I grew up in Oregon, so I’m a lover of coastal upwelling. But just linking back to our Peruvian fisherman in 1578, it’s one of the reasons why fishing is so good in places off the coast of Peru, because that cold water that’s coming up usually is full of nutrients that the fish love.

Okay. So now we understand generally what causes an El Niño and what it is. How much from a, quote-unquote, “average El Niño” does this current phenomenon deviate from?

SWAIN: I think that’s really at the crux of why we’re even having this conversation today. Because if we were having a more, more typical, a weaker moderate event even we, there would probably not be as much focus on it but that’s not what we have this year.

What we already have as of this late September conversation is a very strong El Niño event that is arguably already among the strongest we’ve ever observed at this time of year, and there is very high predictive confidence that it will strengthen further from here, becoming, in all likelihood, the strongest event we’ve ever observed at any point by November or December.

So that is a fairly extraordinary prediction. It’s not the kind of prediction you hear very often for explicitly something that will be record-breaking, and in fact, that’s been the forecast for a number of months now. So this is a remarkably bold forecast in some ways, and so far it has played out almost exactly according to that early forecast. So we are anticipating an extremely strong El Niño event by really by November or December.

CHAKRABARTI: We’ve got 30 seconds before our first break, Daniel, and in terms of the measurement, are we talking about strength in terms of the temperature of the seawater in the area where the El Niño is occurring?

SWAIN: Typically, we measure the strength of El Niño based on how warm, how anomalously warm the water of the eastern equatorial Pacific Ocean gets. So yes, but there are also other metrics we can talk about after the break.

CHAKRABARTI: Actually quickly, how anomalous is it right now? By how many degrees?

SWAIN: Depends on the exact measure that we’re using, but it’s about two and a half or even three degrees Celsius warmer than average, and that’s a big deal in this part of the world.

Part II

CHAKRABARTI: Daniel, I understand that if Pacific Ocean water temperatures at specific places, as you mentioned before, if it goes above — if it rises by about roughly a half degree centigrade, then officially we’re in an El Niño period.

And if it goes above two degrees centigrade, then that’s where we get into super El Niño territory. Is that roughly correct?

SWAIN: Yes, and for those trying to do the mental math to Fahrenheit, we just multiply by 1.8. We’re talking about at the minimum level, a warming of a patch of ocean that’s really only a degree or so Fahrenheit to be minimally qualified as an El Niño event, essentially.

And then as you correctly point out, once we get above about 1.5 degrees Celsius or a little over two degrees Fahrenheit, that’s already a strong event. So it doesn’t take a lot. Doesn’t sound like a big number, but of course, the ocean on large scales, it doesn’t vary as much as the atmosphere.

So it takes a smaller increment to essentially be a big deal. So once we get above that sort of that two or so degree threshold Celsius we’re in fairly rare territory historically in terms of El Niño, and that would be considered a very strong event.

CHAKRABARTI: I understand that getting above two has only happened at, what, two or three times in recorded history?

SWAIN: Yeah, only a handful of times. And that would reach sort of the colloquial threshold for what some folks have termed a super El Niño, which remains a technically undefined term. You won’t hear the federal agencies using it necessarily. But I think the broader notion that there is some tier above strong and that it’s worth distinguishing between the merely strong and the extraordinary I think is fair, and I do think we’re in that extraordinary territory this year.

CHAKRABARTI: Okay. So if it’s above two degrees C, that is in the, quote unquote, “super El Niño” category. I’m sorry, I can’t remember how much higher is it right now already?

SWAIN: It depends a little bit on the measure. There’s actually a couple of different measures floating around now. Partly because the global oceans have warmed so much due to climate change, that NOAA and other agencies have created an adjusted value to make an apples-to-apples comparison with the cooler historical past. So if we use that metric, I think we’re getting close to or we’re already above two certainly regardless. But I think if we use the unadjusted metric, just looking literally at how much warmer this patch of the ocean is than it would usually be at this time of year, we’re now getting above three degrees Celsius.

So that’s above five degrees Fahrenheit, which would be already really the highest value we’ve seen in any September on record.

CHAKRABARTI: And it’s likely to get warmer as we get deeper into the year?

SWAIN: Yes, there is remarkable unanimity among predictive models and predictive agencies that this particular event will become the strongest on record by any objective metric by October or November.

So yes and we’re not even at the peak yet, and a lot of the impacts from this event,  especially away from the equator, might not even peak until after the event peak. So we’re still waiting for the peak intensity of El Niño, and then we might have to wait another month or two beyond that to see the peak impacts in many places.

CHAKRABARTI: Okay. So now we’ve kind of got a hold on what’s happening in this really critical part of the Pacific, and if I can put it in very layman’s terms, we have a giant, the largest body of water on planet Earth is pumping heat to the surface, and then I presume that, is that heat then going into the atmosphere?

How do we connect that with changes that may happen globally in climate?

SWAIN: That’s right. And really, maybe the most important thing to visualize here is that the process of evaporation of water turning from liquid to vapor form it essentially, the rate at which that happens rises very rapidly as temperatures rise.

So as the ocean water itself warms, even if it’s only by a couple of degrees, as is the case with the big El Niño event, that actually profoundly increases the rates of evaporation from that patch of ocean. In fact, this is an exponential process and that’s me talking technically as a scientist.

It literally is an exponent. So you can imagine how if it’s an exponential rise in the rate at which evaporation can occur with each degree of warming, once we get to two or three degrees of warming, that’s not such a small number anymore. We’re talking about increases in rates of evaporation that are starting to be rather dramatic.

And so the way that the ocean actually releases this heat and transfers it to the atmosphere, there’s a little bit of the, you know, conduction going on between the ocean and the air above it, just because the water’s warmer, so the air above it gets a little bit warmer. But the main way that this heat’s being transferred to the atmosphere is in a latent form, in the form of this vastly increased evaporation.

So huge amounts of water vapor entering the global atmosphere, adding latent heat to the global atmosphere, and that is what in turn ends up getting distributed all around the world, affecting the global hydrologic cycle and ultimately shifting storm tracks.

CHAKRABARTI: Okay. So then help us understand why, again, just non-scientists, we like to think in kind of somewhat linear terms.

So I love that we’re in the world of exponential feedback cycles here. But so if we’re having this pump of massive amounts of moisture, as you’re saying, going into the atmosphere, some people might wonder, then why have we been hearing about this super El Niño causing, terrible droughts in some places if we have more moisture going into the air.

SWAIN: Yes, and so this is an excellent point. So one of the things that happens, there’s really two things to understand about how a very large El Niño event like this year’s extremely strong record, probably record strong event, what it does to the global climate system to influence weather patterns in remote regions.

Now, as you might expect locally along the coasts of Peru and Ecuador, it dramatically affects local climate because the ocean can be right along the immediate coast even warmer, something like 10 degrees Fahrenheit warmer than average. That’s pretty dramatic, and that’s what we’ve gotten right now.

So the water’s warmer. It doesn’t get as cool. They have more rain in those regions. That much might be a little bit intuitive, right? Because the ocean right offshore, right outside your doorstep is much warmer. But it’s a little bit less obvious how that translates to droughts in some regions, as you say, and floods potentially in others.

And the reason that happens is there’s two big things going on. One, as we mentioned, a really big El Niño releases a huge amount of heat and moisture into the global atmosphere, so it accelerates the global hydrologic cycle. It just ups the ante overall. There’s higher risk, higher reward.

There’s more moisture available if it is going to rain, but there’s also warmer temperatures and greater rates of evaporation or moisture loss if it’s not raining. So by virtue of warming global temperature temporarily, it just supercharges the whole global hydrologic cycle. That’s number one.

Number two is also in addition to that universal effect, El Niño also acts, if you will, like a ripple in a pond, literally sending wave-like emanations out from this region in the central and eastern tropical Pacific in a way that affects the jet stream. And the jet stream is essentially this river of high velocity air that defines the path that storms take.

So indirectly, this is the way that El Niño can result in very different effects in adjacent regions. Because you might imagine you shift the storm track away from one region and toward another, you’re redirecting a lot of that water from one place to the next.

CHAKRABARTI: Okay, so is that why we’ve been hearing that there may be a less severe hurricane season in the Atlantic because of the jet stream connection?

SWAIN: That’s actually yet another wrinkle in all of this. It does get quite complicated, doesn’t it? But the basic idea there with the hurricanes, and this is actually a prediction that had been made as early as the spring, by the way, that has now essentially been validated as we get through the peak of hurricane season.

The Atlantic hurricane season has been extremely quiet. In fact, I believe we haven’t actually had a single hurricane, only a few tropical storms. That’s one of the least active Atlantic hurricane seasons on record, and it’s not for lack of warmth. There’s been some record warm ocean water, which is hurricane fuel, in places like the Gulf of Mexico and in the subtropical Atlantic.

But the reason why we haven’t seen those hurricanes in that basin is because what a strong El Niño does is it reduces what’s called vertical wind shear, so winds that change direction and strength with height, which are really unfavorable. You can think of them as if they’re strong enough, they like to decapitate incipient hurricanes.

And so the more of it you have, the harder it is for hurricanes to become established. El Niño increases the amount of that storm decapitating wind shear that exists over the Atlantic and can really put the kibosh on hurricane season, as it has this year, but it does the opposite in the Eastern Pacific basin.

It greatly decreases wind shear, can increase the potential risk of hurricanes, and that too is exactly what we’ve seen, where actually the Atlantic has been near record quiet, but the Pacific has been near record active.

CHAKRABARTI: Oh, okay. So and correct me if I’m wrong, but major storms in the Pacific, they’re typhoons, right?

Same phenomenon but called something different.

SWAIN: Depends on the part of the basin. Okay. So right now, for example, there’s a hurricane making landfall in Baja, California, in Mexico. And Hawaii has experienced multiple hurricane events this year as well, and those would be called hurricanes. Now, in the West Pacific, you’re right, those would be typhoons, and it’s just another name for the same type of storm.

CHAKRABARTI: Okay. There’s, so many people, billions of people around the world, and the nations they live in rely on healthy oceans. What effect might the El Niño have just on people and our relationship with the seas?

SWAIN: Yeah, and you’re absolutely right that El Niño is both an oceanic and an atmospheric process.

They are tightly connected. And along, again, in that directly affected portion of the South American coast, Peru and Ecuador, this profoundly affects fisheries and coastal communities because the water is so much warmer. As you correctly pointed out earlier, that means there’s less nutrient-rich water that’s upwelling from the deeper, colder, nutrient-rich ocean.

So the species might be less prevalent or might not be doing as well. So your fishery’s catches, if you’re a commercial fisher, might not be as good. But also, it has significant ecological impacts because and this can extend far beyond the primary El Niño region, all up and down the coasts of North and South America.

In fact, we’re seeing this now all the way up into California already where the water temperatures in Southern California are nearly record warm as well, and we’re seeing the arrival of subtropical species. Both fish and marine mammals and birds and even some venomous sea snakes, believe it or not, are showing up on the beaches of Southern California.

And so it can shift range of species, it can threaten their viability. Everything from kelp forests to marine mammals to sea birds can struggle in this environment, not just because there’s less nutrient-rich upwelling in some cases, because it’s genuinely difficult for a lot of these species to withstand the prolonged marine heatwave that can result, because we usually don’t see heatwaves that are as dramatic in the ocean as we do in the atmosphere. It just takes a lot more energy to heat water than it does air by the same amount. So when we do see these persistent extreme marine heatwaves, whether from El Niño or something else, they can have pretty devastating effects if they persist long enough on marine ecosystems.

CHAKRABARTI: Okay. So everything on planet Earth, all life depends on the climate that we live in. And so I wonder, there are major systems that are quite vulnerable to perturbations in climate, agriculture being one of them. Are there concerns about how in various places around the world, even a temporary shift in the amount of rainfall or the increase in drought might have an impact on global food systems?

The short answer is yes. And one of the concerns about a really strong El Niño like we’ve got this year is that it’s just that. It’s that there are global effects. It’s not isolated to one area, in the same way that a shock to the agricultural system might otherwise be. But you can get multiple simultaneous shocks on different continents.

For example, Southern Africa are likely to see significant drought and that can affect the maize crop there. The Indonesia and the maritime continent also drought, wildfire disruptions to agriculture. But in parts of Southeastern South America, we’ll see heavy rainfall and flooding that could disrupt agriculture, and the same thing is true in the Southwestern and Southeastern United States.

Lots of additional beyond-average precipitation likely this winter in these locations. And part of it is the fact that it’s not just one region, but it’s a bunch of different simultaneous regions, including others I didn’t mention there, that kind of have these disruptions at the same time that causes a big part of the problem.

CHAKRABARTI: Oh, okay. So there’s no slack in the system where it’s happening, when it’s happening everywhere at once. Okay. Can we just stick for 30 seconds with the Southwestern United States, because you just mentioned that people might think, “Hey, actually more rainfall is good on the one hand for, I don’t know a wildfire suppression. But on the other hand, we’re talking about potential lots of flooding events with the sudden bursts of rainfall.”

SWAIN: Yeah, and this is where El Niño in general may not tell us very much, but a record-strength El Niño probably does tell us something quite significant. And it probably will increase the likelihood of a wet winter, maybe even a very wet winter in California, and really the whole Southern tier of the U.S., extending all the way from Central California east to the Carolinas.

So that whole swath of the country. And in some of these places, it probably will result in a significant elevation in flood risk later this winter. Now, the silver lining is it could potentially, if we’re lucky, bring some extra water to the drought-stricken lower Colorado Basin. It’s a little harder to know.

Part III

CHAKRABARTI: Daniel, I’m sorry I had to cut you off there, but you were saying that because of this super El Niño, it is possible, we can’t say for sure, that there could be some, let’s call it drought relief in the Colorado Basin, you said.

SWAIN: So in places like Lake Mead that have got such low water that bathtub ring is getting bigger and bigger every year. Yes, it is possible, although it’s a very tentative possibility in the sense that even if we were to get a very wet winter in this region, it really wouldn’t solve the deep severity of the multi-decadal long-term problem. So it might put us in a better place than we were this year, for example, which some of us will take. But it’s one of those situations where, I’m more concerned this winter about overabundance of water in the Southwest and the southeastern U.S. perhaps than the reverse.

So we’ll have a period of worrying about floods, I think, later this winter across a good portion of the southern swath of the United States. And then we can go back to take stock maybe next summer, see how much water we were able to bank in the Colorado. Fingers are crossed, but it’s very unlikely it would solve the long-term crisis there. But it could still help a bit.

CHAKRABARTI: Yeah, if it did solve the long-term crisis that we’ve been having, it would be an unbelievable amount of water that would have to fall out of the sky, which would produce its own problems. Okay, so you talked about sort of the southern tier of the United States.

Similarly, or not similarly, what could be the potential changes in the northern tier of the United States?

SWAIN: Yeah, so the main thing, the main reason why the southern tier of the continental U.S. generally would be wetter in the winter from a very strong El Niño like this year’s is because the storm track, the jet stream shifts southwards.

So essentially, it shifts the preferred location or the path that storms take or where they might develop and strengthen southward. And in so doing, it sometimes shifts it away from the northern tier. So the Pacific Northwest and the northern tier of U.S. states and much of Canada generally might see a little bit less winter storm activity, and so see somewhat drier conditions, and in some cases, somewhat warmer conditions as well.

That’s more of a up in Canada type of thing. It’s a little bit less distinct across the northern tier of U.S. states. So the clearest signal is wetter across the southern tier from California to Florida and the Carolinas. And then if we’re up in Canada, western Canada generally drier with lower winter snowpack.

Central Canada, warmer winter. The northern tier of U.S. states can be in that transition zone where it’s a little harder to figure out exactly what might happen.

CHAKRABARTI: Okay. In just a few minutes, Daniel I want to come back to something that you said near the beginning of the show, and that is the relationship between this super El Niño and the long-term climate change we have been seeing.

But before that I do want to touch upon a couple other major impacts that this El Niño could have on humanity worldwide. And in order to do that, we spoke with Michelle Nunn, who’s the president and CEO of CARE. It’s the international humanitarian organization. And Michelle says the potential effects of El Niño will be felt even more in places that are already facing hardship and conflict.

MICHELLE NUNN: So we have the magnitude of the conflicts that are happening in Ukraine and the Middle East, which have huge repercussions around the world. So they’re affecting fertilizer prices and gas prices in places like Somalia and Sudan. On top of that, you have the localized conflict in places like Yemen and Afghanistan and also Sudan and Ethiopia and Somalia.

CHAKRABARTI: We also talked about food changes in agriculture with Daniel Swain. Nunn says that in 2025, there were almost 300 million people across 53 countries who already faced acute food insecurity.

NUNN: There’s an estimate that with El Niño, it could push that number up by almost another 50 million people.

And the reason that happens is because the climate is changing. It can be because of drought. It can be because of heat. It can be because of floods. But all of that makes it very difficult for smallholder farmers, who make up the majority of people who are living in poverty, are facing into a very difficult climate.

CHAKRABARTI: And specifically, about the flooding, Michelle says that poses a problem for farmers, as you heard, and also aid workers in the region.

NUNN: In some places that can mean how do we ensure that there’s water catchment and that there’s a way in which we can ensure that we mitigate for flooding as a result of what might be increasing rains?

In other places it is how do we get drip irrigation and how do we ensure that we have solar powered wells so that you don’t have to walk an extra five or 10 miles if you’re a woman trying to provide water for your family?

CHAKRABARTI: And Michelle also says that all of this will have extended consequences, particularly for certain groups of people who will suffer a disproportionate impact.

NUNN: It’s also women and girls who are so often, for instance, the last to eat in their families, eating the least, and are also having the burden and responsibility of, for instance, getting water or taking care of their children to make sure that they’re protected, and there’s a disproportionate impact around gender-based violence when you see the heat increase.

CHAKRABARTI: All right. And finally she told us one more thing, that maybe some of these extra storms are going to happen, as Daniel told us earlier, in Southeast Asia, or maybe there will be drought effects in Africa, or hotter summers in, or hotter temperatures in Europe. So why should U.S. citizens care? Michelle says the global effects of El Niño are something that all Americans should think about, even if it seems that the damage or the biggest damage is happening on the other side of the globe.

NUNN: It is in our economic and our health and our national security interest to ensure that these fragile contexts don’t extend and proliferate so that they end up with more conflict. That, for instance, in a place like the DRC where they’re dealing with Ebola, if they are having to deal with Ebola on top of these other really difficult challenges as it relates to poverty, weather, and the intersection therein, not gonna be able to fight Ebola. And then you see the spread of Ebola.

CHAKRABARTI: So that’s Michelle Nunn, president and CEO of CARE, the international aid group. Okay, Daniel, I’ve got to get back to some fundamentals here that you talked about earlier, because I suppose by this time a lot of people are wondering. We have this record-breaking El Niño happening at a time where we’ve been hearing for years that that sea surface temperatures have been going up anyway due to climate change.

Is that part of what’s feeding this super big, this Godzilla El Niño?

SWAIN: Yeah, and this turns out to be a question that is even more difficult to answer than it might sound, because it’s at the cutting edge of climate science. But I think we have enough time to dig into it a little bit here.

The short answer is yes, that although El Niño and La Niña and ENSO, the broader cycle itself, is a natural cycle that was here long before human-caused climate change, it is something that is profoundly affected by that same climate change and is affecting how we perceive climate change.

So let me explain what I mean by that. Because El Niño essentially is the Earth’s climate system, the way in which it releases excess heat from the tropical Pacific Ocean, which is where a lot of the excess heat goes in the first place, there is simply more and more heat that needs to be released through this mechanism as the amount of global heating increases. A lot of it’s going into the oceans, and much of the global ocean is the Pacific. So there is more sequestered heat, if you will, in the Pacific Ocean that needs to come out as the climate warms. So that might, you might imagine that could lead to either more frequent or at least more intense, when they do occur, El Niño events.

And also, the global oceans are warming in general. They aren’t only warming in the El Niño region, but they’re also warming in the adjacent regions. And here’s where things get a little bit complicated. Interestingly, the long-term trend, the Pacific Ocean has seen a bit of a warming hole right in this eastern equatorial Pacific Ocean region that’s home to El Niño.

Which means that because that patch of ocean has been warming less quickly than the rest of the global oceans, that there is a little bit of an apples to oranges problem, where because that patch of ocean is warming more slowly we need to make that adjustment factor to how we measure El Niño that I was talking about earlier. But the reality is the oceans are still warming, and as they warm, it is becoming easier to achieve certain thresholds of absolute ocean warmth, as you’d expect.

CHAKRABARTI: So can I just jump in here for a second? Because now I wonder if there’s also another kind of feedback loop in operation now with El Niño. Because if El Niño raises the temperature in this part of the Pacific, even if it’s just temporarily, and then it changes climate around the world, when the sea temperature, ocean temperatures go back down, do they go back down to a higher level, essentially a new set point which is higher than it was before?

SWAIN: And that’s the trillion-dollar question because in a climate that wasn’t changing, that was stationary over time, that wasn’t warming, the answer is largely yes, that the climate system should temporarily warm for six to 12 months during a big El Niño event and then cool afterward during the subsequent La Niña, the cool phase, pretty much back to where it was before, steady states.

A warming and a cooling, if you will. We still get that warming and subsequent cooling, but the problem is because the climate change is still there lurking in the background, we’re probably not going to cool back down to where we were before this big El Niño event. And so that’s what we’re beginning to see is that historically, the way we experience global warming is in fact that we see these huge stairsteps up- upwards during big El Niño events temporarily record-breaking global warmth.

We see a little bit of relative cooling thereafter, but we don’t return to our old baseline. It stays elevated. So that’s the mechanism by which we’re experiencing global warming is in this staircase, this escalating temperature staircase toward warmer temperatures punctuated by these El Niño warming periods and then slight partial cooling or plateau periods during the subsequent La Niña events.

So that’s what we’re expecting this year. By late 2026, we’ll probably have record-breaking global warmth. Again, likely to persist into 2027. So that’s a key aspect of how we’re experiencing all of this.

CHAKRABARTI: So on an immediate timescale, the next, few years, as you’re saying, even within the lifetime of people currently living, this sounds gloomy.

But do you have any optimism in this case about what we can either learn from this El Niño or about its climate impacts overall, Daniel?

SWAIN: El Niño is itself a natural process. Yeah. And it’s been around for all of human history, and it seems destined to continue even with global warming.

And it’s something that’s important that we understand because it does have all of these cascading global impacts we’ve been talking about from agriculture to water supply to global security. So it’s important to understand it. This kind of huge El Niño event will, it certainly will offer a scientific opportunity because it’s a big push to the system, if you will.

So large signal makes it a little bit easier to study. The challenge is that this could have some really negative impacts for millions of people in the meantime. But I do think we’ll probably be able to glean some interesting and important societally important scientific understandings from what ends up happening this year.

And I think the other thing I would add is that we talk about climate adaptation. Forget El Niño for a moment, but just thinking about how climate is changing the risk of extreme weather events and droughts and food supply disruptions and all these sorts of things. We want to increase our level of societal resilience to those regardless of why they occur in a particular year.

This is something that’s important for human health and wellbeing all around the world. And so a lot of the same things that we might do to respond to a really big El Niño event or that we might do to adapt to a warming climate to make our society more resilient are, they’re similar. And so the better we can learn from one of these events and apply it to the other, I think the better off we will be because a lot of the things we need to be doing are overlapping there.

CHAKRABARTI: That’s a really good point. In the last 30 seconds that we have, Daniel, are you a betting man?

SWAIN: I am not.

CHAKRABARTI: Okay. Because I was gonna ask you, do you have a prediction about how warm it could actually get?

SWAIN: I think the good money is definitely on record warm. In fact, right now it does look like late 2026 into 2027, there’s something like a 95% chance, maybe even higher, that we’ll see a new record-breaking global temperature as a result of global warming plus this big El Niño event.

So those are pretty good betting odds, I would say.

This article was originally published on WBUR.org.