The Decibel - Why El Niño is a climate wild card

Episode Date: July 10, 2023

El Niño is back in a big way. This natural weather pattern is known to increase severe weather around the world. And scientists are trying to predict the impacts of this climate wild card – especially on top of global warming impacts.Ivan Semeniuk, The Globe’s science reporter, has been investigating the effects of El Niño. He’ll explain the impacts of El Niños in the past and what to expect this time around.Questions? Comments? Ideas? Email us at [e-mail]

Lately, it's been really hot. Last week, we even had the hottest day ever recorded on Earth. But yeah, it's been like the past five days have been super hot and insane. So not what I'm used to. It's getting worse year by year. It's getting worse. I mean, we feel like we're burning up. And over the next several months, it's likely going to be warmer than average. That's because of El Nino.

It's the first time we've had a significant El Nino in several years. The last major one was in 2016, and that was the hottest year on record. So scientists are racing to try to figure out what the impacts of this El Nino will be, especially on top of the global warming that we're already seeing. Ivan Semenik is the Globe's science reporter. Today, he'll tell us how El Nino actually works and what we might be in for this time around. I'm Mainika Raman-Wilms, and this is The be in for this time around. I'm Mainika Raman-Wilms, and this is The Decibel from The Globe and Mail.

Ivan, thank you so much for being here today. Thank you. My pleasure. So we know the science behind El Nino is fairly complicated, but I want to give you a bit of a challenge here, Ivan. If you had to summarize it in just one sentence, what exactly is El Nino? In one sentence, it's a seesaw pattern that connects the Pacific Ocean with the atmosphere with consequences that reverberate around the globe. Okay. Thank you. That's actually very impressive. Not too bad. not too bad. That was pretty good. Okay, so what does it take for an El Nino event to actually happen?

Like we know that this is kind of a cyclical pattern, it sounds like, but what causes it? Sure, let me unpack this a little bit. And even though it's a cycle, it's one of those cycles that, you know, isn't perfectly predictable with the same regular frequency. For example, it's not as predictable as the regular seasons of the year.

However, I would say El Nino is by far the most important climate pattern apart from the annual change of the seasons. So it really is a strong signal in the climate. And it reflects the influence of the largest stretch of open water in the world, which is the Pacific Ocean. So what's happening here is there's a sort of normal mode in which the Pacific works, where you tend to have easterly winds blowing along the equator. They're dragging water westward toward Asia, from South America, actually, along the equator towards Asia. And then you kind of have a piling up of warm water on the extreme western side of the Pacific,

the Asia side of the Pacific. That tends to make that part of the world very wet. And then you sort of have dry air going kind of over the top and going back towards the Americas coming down and creating kind of a cooler, drier climate, which is, you know, just immediately to the, you know, on the Pacific side of South America. So that's the normal pattern. That's the normal pattern. That pattern can get short circuited, though. Every two to seven years, things swing the other way. So the winds weaken.

There tends to be a warming of waters. If the winds aren't moving as quickly, then the waters tend to warm up closer to the South American coast. And then you start to have this pattern where it gets quite warm and wet over on the American side of the Pacific and much drier on the Asian side. So then that kind of reverses the normal pattern. You then tend to get drought in places like Indonesia and Australia. You tend to get a much wetter winter, especially in the southern part of the United States. Other changes across South America. There are also changes that reach across to Africa, for example, and Southeast Asia. So there's a kind of domino effect when all

of these changes take place. Okay, so what's the criteria for something to actually be considered an El Nino event? It's basically a delayed response. You know, what's happening is, as I was saying, you sort of got this connection between the ocean and the atmosphere. Ocean waters are carrying a tremendous amount of energy. So even just a little bit of a rise in temperature of ocean water can have a huge reverberating effect on the atmosphere. And you sort of think about something like a cycle in your freezer, for example, or your furnace, like a thermostat that gets to be this critical moment, and then suddenly the thermostat clicks on, or the freezer clicks on when a certain

threshold is reached. And so you get, not to be hand wavy, but it's actually a fairly complicated pattern. So the change is not easy to predict. The thing that makes an El Nino or the official definition of an El Nino is you have a region of water in the eastern Pacific where if it gets more than half a degree above average for three months running, that officially becomes an El Nino. We reached that this year, just a month ago. So that's the criteria for an El Nino. So half a degree warmer in the Pacific, essentially. So that tells you if you're in an El Nino or not. It doesn't tell you, though, how strong it's going to be, how long it's going to last, or how long before the next one. So these things are much more variable. And as you kind of touched on this, Ivan, but we don't really know why this

happens. Is that right? And we know roughly why it happens, because there is this ongoing cycle. And it's sometimes, the larger cycle that it's part of is called ENSO. It's the El Nino Southern Oscillation. So it's basically a quirk of geography. If you take the continents, you take the Pacific with the shape and kind of put the solar energy into it that's coming from the sun, and you sort of get this kind of repeating pattern occurring again and again. It's a bit like a seesaw, as I said, kind of going back and forth. But there are enough variables in that seesaw that it's not perfectly predictable like clockwork. Okay, makes sense. There's also La Nina, which we hear about as well. So what's the difference between El Nino and La

Nina? La Nina is the other end of the cycle. So that's where it's kind of warmest and wettest in Asia, coolest and driest in the Americas. In terms of how you define it, instead of that section of the Pacific that I talked about being more than half a degree warmer, it's more than half a degree cooler. So we've been in a La Nina condition really since the beginning of 2020, coincidentally, basically since the beginning of the pandemic. So that's been persistent. It's defined weather patterns across North America, especially for really for the last three, four years. So now that's shifting. Okay.

And I'm just curious, where did the names come from? Oh, that's easy. When you don't have that wind that's pulling the water towards Asia across the equatorial Pacific, then you have this buildup of warm water. And this really tends to manifest itself in the wintertime. So around Christmastime, you know, fishermen off the coast of South America would notice this really unusually warm water. And because it's around Christmas time, they would call it El Nino, which is like the child, the little boy after... Oh, like the Christ child. The Christ child, exactly.

And El Nino sort of then becomes the opposite of that. Yeah, yeah. Okay, so let's talk about the current El Nino. As you said, these happen every few years. So why is this one getting so much attention? Well, I think partly because climate change is also in the mix. And we're increasingly focusing on the impact of climate change. We're seeing that impact all of the time. One of the side effects of El Nino is it warms the planet a little bit. It's during an El Nino that the average temperature of the globe tends to bump up a little bit and then it kind of bumps down a little bit during La Nina years.

Of course, that's overlaid on top of this gradual rise from climate change. So one thing that's interesting about the last strong El Nino in 2016, that also coincides with the warmest year on record in terms of average global temperature. One question, especially if this were to turn out to be an especially strong El Nino, people were beginning to speculate this spring if this El Nino might actually take the average global temperature over the threshold of 1.5 degrees over pre-industrial temperatures. And 1.5 degrees is that limit that countries that have signed on to the Paris Climate Agreement have said they're trying to avoid crossing that line.

Now, that doesn't mean that El Nino would keep us there, but it might, you know, temporarily take us over the line and then back down. a harbinger of what's to come, because since it amounts to a bit of a warming, it's also showing us what conditions are going to be like more permanently, you know, in another decade or so as kind of climate change moves us in that direction. So that's one reason for the interest. And of course, there's just this additional question about whether or not climate change is making El Nino itself more pronounced or the effects of El Nino more severe? That's an open question. Oh, interesting.

So kind of one could affect the other, like either way, essentially. You mentioned that hot weather is something that we're looking at. So the last strong El Nino, we saw the increase in temperature. I'm just thinking we've seen really hot temperatures already at the beginning of July in many parts of the country. Is that a result potentially of El Nino? I think it's too soon for that to really point to El Nino for that. As I say, especially in the northern hemisphere, you're really going to start to see the effect of a stronger El Nino into the winter months.

But it shows we're already in a warm situation. So what that might mean for the winter is an interesting question. In Canada, for example, it could mean a lot less snowfall. I think there's an easy story to tell about this El Nino, and I would caution against the easy story. The easy story is El Nino's coming. Look out, bat in the hatches. It's going to be bad news.

And it may be bad news for some places for some time for specific reasons, you know, if it brings a flood, if it amplifies dry weather, certainly not to be taken lightly. But it's a complicated, nuanced phenomenon. And I think it's too simple to just say it's a bad thing that we should be afraid of. I think more important is that, you know, this is a natural part of the climate cycle that, you know, it is a bit of a wild card. It shifts the normal weather of certain regions into a different state. And there's an interesting question about how that interacts with climate change, the fact that we're on a warmer planet. All of these are good questions to be exploring and thinking about, and that's what scientists are doing. But I wouldn't say that universally,

it's bad news. It's just another part of that cycle. We'll be back in a minute. Okay, so we know El Nino is kind of a wildcard climate event, but what have we seen from previous El Ninos that can kind of give us a sense of it? We know that they're coming every two to seven years. We know that some are more intense than others. Among the most intense in the last 40 years or so, there was a very strong El Nino in 82, 83, another one in 97, 98. And more recently in this century, the strongest El Nino has been around 2016. I think when you see El Nino stories coming up in the news, there are some classic photos that keep cropping up again and again. And some of those, there's a particularly strong El Nino in the late 1990s. And there's a classic shot of these homes on a cliff off the coast near San

Francisco on California, where they're, on California, where stormy weather was kind of eroding this cliff. So these kind of epic moments like 82, 97, and to some extent 2016, sort of define our sense of El Nino. I think I remember reading somewhere that the Quebec ice storm in the late 90s, right? Wasn't that related to an El Nino year? Well, there's a lot to that. So, of course, that was a big, strong El Nino year.

And you look at some of the effects that happen with El Nino, it shifts the jet stream, for example. And, you know, one of the consequences of that is sort of shifting the freeze-thaw line in the winter, you know. And it's near that zero line, that freeze-thaw line, that you tend to get things like ice storms, you know, and it's near that zero line, that freeze thaw line, that you tend to get things like ice storms, you know, where, where you have rain turning to ice, clinging to trees, clinging to structures. So when you have the effect of El Nino kind of shifting that line,

places that aren't normally used to getting kind of rain, which then freezes and, you know, kind of creates a classic ice storm, suddenly that appears. So I think that's a good example of how El Nino is a bit of a wild card or how it changes the game. Yeah. So let's actually talk a little bit more about the human sides of this, right? Because this sounds like it's an important part of it. So what impact does El Nino typically have on, I guess, different industries, different businesses, especially things that rely on water. Right. So again, just to stick to North America for a minute, really the biggest effect in North

America tends to be the precipitation patterns. So it would be warmer in the Northwest, less snowfall as a result. So, you know, everything from skiing or, you know, sort of snow related industries are affected, but also hydroelectric generation, you know, if there's less snowfall means less runoff, less water and behind reservoirs and so on. So if we're getting energy from dams and things, that'd be less. Exactly. So there's that effect. If it's wetter in the American South, you can imagine increased potential for flooding. On the other hand, in places that have been dry in the American South and the fact that, you know, there are water issues there that could benefit if it brings more water.

So there's sort of, you know, there are pros and cons. Yeah. And do we have any sense of kind of the economic impacts of El Nino? I mean, I guess this would be kind of, you know, big numbers to look at. But do we have any idea? study that got a lot of attention in the spring. This is a pair of researchers at Dartmouth College in the US. What they found is that after an El Nino year, because of the various changes that El Nino brings, there is an economic cost, and that that cost lingers long after the El Nino. So for a few years, the economy doesn't immediately bounce back. They calculated the cost, for example, of the 82, 83 El Nino to be about $4.1 trillion on the economy overall. For the 97, 98 El Nino, they found it $5.7 trillion. This is globally. Global economy. Based on those numbers, and they kind of extrapolate to ask what happens as we go into the 21st century, especially as we add the effect of El Nino on top of climate change.

And they're saying, you know, El Nino could potentially cost the world up to $84 trillion across the whole century as a result of the various weather effects that come from El Nino. In this most recent El Nino, the one that's just coming now, they say it could cost up to $3 trillion. But I'm going to put some big caveats on that. There are so many uncertainties with this and so many variables that I think other experts are more cautious about these predictions. And just note the fact that, you know, some places benefit from El Nino. Some industries do better. It ends up being very regional, sometimes very local. So in our story in the Globe and Mail, for example, we focused on cases like the oyster industry in BC.

That's a good example of an industry where there is concern about El Nino because it means warmer ocean temperatures along the BC coast, which can have a negative impact on oysters if it reaches kind of a critical state. So there can be, it sounds like, a lot of negative effects, but also it sounds like there could be benefits depending on the region of the world that you're in. Right, and just to complicate things economically, if other parts of the world are even more negatively affected, it might sort of benefit you in the sense that prices are going up and you've got your crop in the ground

six months ahead of South America, so it might benefit you indirectly. Okay. Just lastly here, it sounds like there's a lot to think about, but is there anything that we can do as individuals or that governments can do to much whether El Nino would become worse with climate change, but whether the extremes would spread apart more. So in other words, the difference between El Nino and La Nina could potentially become more pronounced. So that means dry or dry, wet or wet, warm or warm, cold or cold. And when planning for, you know, whether you're planning for your home, your community, your region, not to just think

about, okay, with climate change, we're moving to warmer climate, we're maybe moving to this overall trend, but also thinking about increased variability. And we know that climate change already will make weather more variable, but a more pronounced El Nino cycle would add to that variability, which means you need to plan for a wider range of possibilities. More wet years, more dry years, maybe more extreme heat, maybe more cold snaps as well, And just thinking across that board. So I think that could pose challenges for our infrastructure. Ivan, thank you so much for joining me today.

My pleasure. That's it for today. I'm Mainika Raman-Wells. Our summer producer is Nagin Nia. Our producers are Madeline White, Cheryl Sutherland, and Rachel Levy-McLaughlin David Crosby edits the show Adrienne Chung is our senior producer And Angela Pachenza is our executive editor

Thanks so much for listening, and I'll talk to you tomorrow