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How hurricanes are warming the oceans and shaping Earth's climate

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The devastating impacts of hurricanes on land are well known, but they cause changes to the oceans as well. While conventional thinking tells us that a hurricane cools the water after it passes, that's only partially true. The surface cools, but the deep ocean? It actually heats up.

With the peak of hurricane season upon us, Sally Warner, Associate Professor of Climate Science at Brandeis University and Noel Gutiérrez Brizuela, a Ph. D. graduate from the University of California, San Diego, join the podcast to discuss their research on what happens as the storms move over the ocean and what it means for climate change.

Read more at The Conversation: Hurricanes push heat deeper into the ocean than scientists realized, boosting long-term ocean warming, new research shows

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About the Across the Sky podcast

The weekly weather podcast is hosted on a rotation by the Lee Weather team:

Matt Holiner of Lee Enterprises' Midwest group in Chicago, Kirsten Lang of the Tulsa World in Oklahoma, Joe Martucci of the Press of Atlantic City, N.J., and Sean Sublette of the Richmond Times-Dispatch in Virginia.

Episode transcript

Note: The following transcript was created by Adobe Premiere and may contain misspellings and other inaccuracies as it was generated automatically:

Welcome, everybody to another episode of the Across the Sky podcast hosted by our Lee Enterprises weather team. I’m meteorologist Joe Martucci, based at The Press of Atlantic City on the Jersey Shore. Here it is, hurricane season. It's been hurricane season since the beginning of June, but now we're really starting to ramp it up the peak of hurricane season right around September the 10th.

And this episode, we're going to talk about hurricanes. We're talking about it's impacts on warming the ocean and the deep ocean. And that's actually some research that really hasn't been done much in the past. We have to researchers Sally Warner and Noel Gutiérrez as well, who are on to talk to us about it here. We have Matt Holiner in the Midwest on the pod, Sean Sublette at the Richmond Times-Dispatch and Kirsten Lang at the Tulsa World.

It was it was a good episode. It was kind of it was neat to have Sally, who's in Massachusetts and Noel, who's in San Diego, kind of come together from both coasts for this episode. Before we get going, Matt, Sean or Kirsten, anything we could say before we hop into the interview. But I think for me it was very interesting to dive into how you know and look.

A lot of times what we focus on is the sea surface temperature. The keyword there is surface. And what their research focuses on is what's going on below the surface. And how do the hurricanes we we have a good understanding of how they impact sea surface temperatures. But what their research really focus on is how they're affecting the temperatures below the surface and the long term implications of that.

So just like how this dived a little bit deeper into what we as meteorologists mainly focus on, which is what is happening at the surface. But you really get the full picture of what's going on in the long term implications of you have to dive down and look what's going on below the surface. And so it was really good to talk to them and hear the process about how they were measuring those temperatures as well.

That was very interesting to hear. Yeah, it was interesting to hear about how not just how they did it, the shifts that they had to take to do this, but it's a good reminder of the time scales that we're working on here for their research. I mean, obviously, when we're all meteorologists, we know that warmer water fuels more hurricanes.

But as you alluded to, Matt, we need to talk about the surface and and how far down is the surface before we start getting into the deeper water and pushing that relatively warmer water deeper down into the ocean. And these are all very important, fundamental long term questions there. They are just starting to bring forward. So it was really good to have them on.

Yeah, I know. Dive too a little bit into the implications of of their findings that they had throughout their research. Awesome. Without further ado, let's get into the air.

So when we often talk about hurricanes, we often talk about the destruction in its wake on land. However, we should also focus on the powerful impacts hurricanes have on the oceans as it passes through as well. Research by our next two guests here show that hurricanes ultimately help warm the ocean, giving future storms more warm water fuel to work with.

And we are very happy to have on Sally Warner, who's an associate professor of climate science at Brandeis University in Waltham, Massachusetts, and on the other coast in San Diego, we have Noel Gutiérrez as well, who is a recent Ph.D. graduate. They both worked on this research project. What we found in the Conversation website, you can check out the piece that they have there.

It's titled Hurricanes Push Heat Deeper Into the Ocean Than Scientists Realize, Boosting Long Term Warming. New research shows. So Sally Noel, thanks for hopping on today. We appreciate it. Thanks for having us. Thanks for inviting us, Joe. Yeah, totally. Glad to have everybody here and on both coasts. We've got everything covered for you. My first question is going to be a 30,000 foot question here.

You know, for the everyday person and let's say it's someone who doesn't live near the coast, What would you say is the main takeaway from this research? I would say, you know, we typically look at hurricanes as extreme events that just last a couple of days and events that result from that, from everything else that is going in the climate.

But I think our research contributes to this different perspective of hurricanes being active shapers of the world, don't we? Meaning their effects don't start in when the hurricanes up in the air, but rather they are a crucial element shaping the seasons and ocean currents and everything else that really makes this world the way it is. Gotcha. How are you able, Mike?

As I'm reading this article, my one thing I'm wondering is how were you able to research, you know, what happened actually deep down in the oceans and not just what happens at the surface. You know, we often, you know, kind of common knowledge that, you know, we don't know a lot about the ocean still yet, let alone the deep ocean.

So how did you get involved in researching what's happening deep down there? So Noel and I were on a research cruise back in 2018. We were on a research vessel, Thomas G. Thompson, which is operated by the University of Washington. And we were kind of close to the Philippines when we did between the Philippines and Palau in the in the Western Pacific when we did this research and we used this instrument called a microstructure profiler.

And what it does is we drop it down and it goes it falls down through the ocean and we are able to measure the top 300 meters, which is almost the top thousand feet of the ocean with this instrument. And this instrument measures things like temperature and salinity. Those are kind of basic oceanographic measurements, but it also measures turbulence and it measures like shear in the ocean or very small little motions in the ocean.

And so we're able to understand what's happening below the surface by using this instrument and we drop it down and then we pull it off and we drop it down and we pull it off and we drop it down and we pull it up over and over and over. So we did thousands upon thousands of cars while on this three research cruise back in 2018.

You research cruises, have all you can eat buffets and waterparks of that. Definitely no water parks, that's for sure. And you know, the food the food can be pretty good and it is all you can eat, but it is limited to meals at certain times. And and when we're on ships, we're working 12 hour watches or 12 hour shifts.

Our crew usually does three, 3 to 3. So some people work 3 a.m. to 3 p.m. and other people were at 3 p.m. to 3 a.m.. So you're going to miss some of the meals, but there's always a fridge with leftovers and there's some cereal. Perfect. Yeah. Yeah. And I think one special thing about our measurements is that we were actually running this Chameleon Microstructure device that Sally was describing.

We were running that operation 24 seven and so that's, that's an important piece of the measurements, which we are also, I should say that the research Christmas funded by the Office of Naval Research from the US Navy and this was a huge project designed to better understand intra seasonal weather, specific things like that. Well, like the summertime. M.J. Oh, the managing situation.

And there was a lot of different labs involved. This particular part of the project that we were involved in was allowed by the Oregon State Ocean Mixing Group and UC San Diego Multiscale Ocean Dynamics and a dive into the details a little bit more. When I first read the article, it kind of stood out as a surprise to me because as meteorologist, one thing that we often talk about is how these storms actually cool the oceans.

And so if you have a storm coming in right behind one storm, usually that storm weakens because the sea surface temperatures actually go down. And usually that takes out some of the intensity of the storm right behind a leaping storm. So it was interesting to me that actually we're talking about a warming scenario. So can you clarify what the difference is between the immediate cooling behind these and the long term feeding kind of dive into the details here?

So, yeah, that's counterintuitive. You're right, Matt. And yeah, most of us know that at least meteorologists are told like, you know, the ocean has a layer of warm water lying on top of cold water. And when a hurricane comes by, it makes sense. So both of those layers of water, so the surface ends up being colder than usual.

And that's true. The part of the story that most meteorologists care about is how about colder than weakens later storms, as you mentioned, But few people realize and Kerry Emanuel made a really good point about this back in 2001. And research sort of continues that the hypotheses that he laid out is when you mix when you mix, there's two masses of water, one cold, one hot for every volume of cold water or anomalously cold water.

You're going to have hot water, right? So like by mixing the hot water is cool, but at the heart, the cold water is a warmed. So below the cold wake of the cyclone that you see in the surface from a satellite below that there's going to be a of deep water that received water from the surface. And so we're really working at different time scales here and rather than caring about what what the air sea interactions are going to be in the next, say, 3 to 10 days, we're thinking, okay, what's going to happen to this extra heat in a timescale of months to years?

That kind of leads in. Then to my next question that I have for you guys. And it's kind of a broad question, but what have you found are really kind of the implications of your studies here? So the big implication is that by mixing this water, the hurricane comes, it mixes the water, it pushes heat into the thermocline.

We like to say 100, 150 meters depth by putting that water there or that heat there, that extra heat becomes available to be transferred by large scale ocean currents. So by it means that the hurricanes are supplying heat to these currents and therefore having remote impacts on climate because those currents will take the warm water and that will allow the heat to impact weather and other parts of the world.

So the the field experiment was in the Western Pacific. Do you feel comfortable extrapolating these results to the Atlantic basin, even though that's not where, you know, the warmest water on the planet is and and Indian Ocean basins? Do you kind of feel like this idea holds as you as you change ocean basins, as you go a little bit farther away from the tropics toward the middle latitudes?

Is there anything that that cautions you to to extrapolate these results further? Yeah, I think that our results are fundamental in the way that in the sense that we can really expect this to be happening in every ocean, everywhere where there's a hurricane passing over warm water. And the reason that is the case is because I'm so what we observed is that there's four weeks after the hurricane, there's an active transfer of heat between the seasonal and permanent thermocline.

So things like water or heat being taken away from water at under 250 meters depth and it's being pushed down all the way to like 200 meters. Wherever you have that structure of water that's going to be happening. And that is due to the to the effect of these things called near inertial waves, which you can think of them as the sort of ocean's reverberation to the forcing of a cyclone.

So all the energy that gets put into the water during the journey of the hurricane, that's going to go somewhere. And where it goes into it organizes into these waves and the waves continue of the active heat transfer for weeks. So yeah, it can be generalized to pretty much every place that's going to follow up in there. Because you were saying waves before, I think you mean that figuratively, not literally, right, Because you just go into it a little bit more in depth, maybe to break it down.

So we actually do mean literally. So when you typically think of waves in the ocean, people think of surface waves. So waves that are at the surface of the ocean and in a physical sense, they're at the boundary between the water, air interface and water and air have different densities. And actually waves can form pretty much on any boundary between fluids of different densities.

So even though the waves that we see on the surface are the most obvious, because we can see that we actually see waves deep in the ocean as well between warmer water. But so you have a layer of warm water on top and a layer of colder water below that interface Between the warm and cold water. There's a density difference between those two layers and waves can form on those layers.

Yeah. So we have internal waves and they can transport heat downwards. And so yeah, so when we say near inertial internal waves, these are actually physical things that are happening below the surface in the ocean. Got it. Awesome. All right. Well, thanks for the explanation, Sally. Appreciate it. We're going to take a brief break and we'll come back on the other side.

You're listening to the Across the Sky File. And we are back here. We are talking about research done by our two guests here, Sally Boyer and Noel Gutierrez as well about ocean warming, not at the surface, but below the surface due to hurricanes in their field work and experiments in the piece that we read in the conversation drove us to having them here today.

And we appreciate that when we talk about, you know, ocean waters and temperatures, the high, no pun intended topic has been how warm it's been and especially Atlantic Ocean, near record to record warm temperatures. We haven't had much in the way of, you know, hurricane development so far this season. My question for you is, you know, can we relate any of this to climate change we've seen over the past couple of decades or any projections with this as we go forward, you know, relating your research to hurricanes and, you know, just generally water temperatures that we've seen in the Atlantic Ocean, I'll start just by saying that the warming, the ocean is certainly a very

worrisome topic with respect to climate change. Like the oceans have absorbed over 90% of the excess heat that we put into the atmosphere. And right now we're seeing like massive coral bleaching events happening in places like the Florida Keys and with the El Nino that's happening right now, we expect that coral bleaching to get a lot worse. So just in general, thinking about heat in the ocean, it's a topic that really worries me and it's only going to get worse with climate change.

So I just wanted to make that comment about heat in the ocean. But no. Well, if you want to talk more about the wider implications of our research for for climate change. Yeah. So I think where our research comes into the picture here is in really explaining how exactly the ocean has been able to absorb that 90 plus percent of extra heat due to global warming.

Right. Temperature of the ocean is one of those things that many scientists we sort of take for granted because it will go into the ocean and we'll take our temperature sensors and we'll see, okay, this is the temperature structure, but we got to realize the heat needs to get there somehow. If we see heat at a thousand meters by 500 meters, whatever it is, to get there somehow and the input of heat for the ocean is the sun.

So what our research really does and the big like very big picture of understanding the ocean is giving us one important mechanism by which the heat is transported from the surface where the sun puts it, and then it's transferred to to great depths. And I think it's great that you are really diving into how the temperatures are transferred from the surface to those depths and how they influence hurricanes.

Well, that's kind of what I want to go at next, because oftentimes I think that's what a lot of the buzz has been this summer is focusing on sea surface temperatures and how at the surface, all these temperatures are very much above average. And how I think the public now has an understanding and that's been well published, that when you have higher sea surface temperatures, it gives these storms more energy, allows them to become more intense.

But how much research has been done with how those waters at that affect the intensity of the storm? So how much is it really just about what's at the surface versus what's happening deeper down that affects the intensity of these storms? We know so much about the temperature of the surface of the ocean because we can measure that with satellites, but satellites only measure the surface.

They don't measure what's below. And when we think about hurricane strength, you can imagine if there's like a very thin layer of warm water on top of colder water below, then as the hurricanes come through and mix up that cold water like you were talking about before, that cold water would serve as a dampening effect on the storm because there's less heat to energize the storm.

Whereas if you have another scenario where you have a very thick, warm layer on top of the cold layer below, then there's a lot more energy and even as the storm mixes the water, there isn't as much cold that's able to come up. There's still a lot more heat energy to that storm. So the depth of like it really does depend how deep the warm layer is, because that's the energy that's provided to the storms.

And the way that we understand deeper temperatures. I think the Argo program. So there's these floats called Argo floats like they're the size of like a like maybe three fire extinguisher features. Like if you were to put them end to end, that's about the size of the floats. And there's over 3000 of them in the oceans and they measure temperature and salinity in the top 2000 meters of the ocean and and the data as freely available.

They cover pretty much the entire ocean except the Arctic. And so they may send their their data to satellites. And so that's a way that we can understand what's happening below the surface where satellites can't see, maybe since like the mid 2000 agencies, like no other weather services, they've been aware of this problem that really to understand hurricane development, you get somewhat clear picture of what's under the surface.

So Argo and other tools are being integrated into weather prediction models. However, they're like there's still some really big questions, especially in the turbulence part of how the layers of water with different temperature mix because that's really, really difficult to measure. And yeah, that's the fact that we were able to measure that consistently for so long was really well for us to get these new results.

And I think that's one of the big frontiers in terms of improving our hurricane prediction models, like really getting that mixing part a little better, especially when there are variations in salinity involved because that's where things are really tricky and that's a hot topic among forecasters right now. Yeah, back to that point about the turbulence, I know that in meteorology turbulence is also just as thorny of an issue, but I just I want to try to get a sense of scale vertically, you know, to the depth of ocean.

When we talk about the turbulent mixing of a tropical cyclone, Hurricane, is there a sense as to how deep are we mixing from the lateral surface surface to to how deep are we typically mixing water to depth when when a let's say a cat four, cat five hurricane goes by, obviously stronger hurricanes are going to mix, mix ocean more deeply.

But so many times we hear the term sea surface temperature one, How deep is that? How deep is the surface? When we talk about sea surface temperatures of five meters, ten meters, 50 meters, and then approximately how deep to a first approximation do do these storms mix water down in the short term? Not so much in the in the multi-month term, but as these things kind of go by to answer that the best that you can.

Yeah, So that's a great question. One of the hurricane is over the ocean. It's generally mixing water in the top 100 meters so that the warm layer that Sally was thinking about, that's where most of the the most of the mixing is happening at the bottom of that warm layer. So say of the surface ocean is 29 Celsius wherever you have water of that temperature and it starts to get colder.

That's where most of the mixing. So, you know, that's generally 50 to 100 meters depth. And that's so that's the range of depth when the storm is literally over the ocean. And then what we discover with these measurements is in the following weeks, the energy into the ocean by the storm starts to move deeper and deeper through these internal waves.

So the layer maximum mixing groups from 50, 60 meters and it starts going down and we saw it going to 250 meters. We really as far as our measurements went, there was mixing happening. So we we sort of have a low bound, deep this coast and it it might continue for much deeper. So my question is kind of where do you guys plan to go from here?

You know, you got some really good information from your studies, from your research that you did. Obviously, you're conveying that, you know, to the public. But what's what's your next step? What do you plan to do sort of the long term question that I'm going after at this point and that this research ties into is and to really understanding the role of and the background climate.

Right. So we we usually face this question of what is signal and what is noise and historically, climate scientists have considered weather to be noise. But the way we are looking at it right now, at least from my perspective, is that weather is noise that feeds into the signal. And there's a lot of different ways in which that happens.

We made this case study with tropical cyclones and now I'm looking to expand that into broader weather pattern also in the mid-latitudes and developing tools that will help forecasters and other prominent modelers to put these processes into their into consideration and whatever studies they're doing, because, you know, turbulence of these near inertial waves, they have relatively small scales in the ocean.

So these are scales smaller than most models are able to resolve correctly. So we need to come up with simplified ways to have these problems processes into account. So that's, I think, where the where the next goal is, really seeing what other type of weather systems have this type of effect and finding simple ways to to account for them in models and predictions.

So this isn't anything you can stop. I mean, you can't stop a hurricane from forming, so you can't stop this mixing from occurring, correct? It just it just is. And you hit on a really interesting point because we usually look at hurricanes as this poster child of climate change. Right. Like even Al Gore and An Inconvenient Truth, he dedicates like a good section of his speech to talk about hurricanes of their destruction.

And while it is true that hurricanes are, you know, devastating in many cases, they at the end of the day, are intrinsic part of our climate and the mixing that they drive and the warming people cause is also just a fundamental part of how climate works. So and yeah, it's a it's always been here before humans were even on the planet this morning.

And I think we also have to remember that actually one of the things that we're kind of concerned about in terms of like mixing in the ocean is actually a good thing. And one of the things we're concerned about is actually a slowing down of mixing with climate change, that as the surface water warms and becomes warmer from heat from the atmosphere, heat from the sun, we are warming the surface faster than we're warming water below.

And that's actually making it harder to mix the surface water down or the deeper water up. And this has other implications in the ocean that we need that mixing. We need to be able to mix nutrients upwards into the surface water where microscopic phytoplankton, which are that's a fancy word for algae. They photosynthesize as and provide over half the oxygen in the Earth's atmosphere, but they need nutrients in order to grow, and that has to be mixed up from below.

There's this is where we need to mix the oxygenated surface waters down deep. So mixing is a really important process in the ocean. And with climate change mixing, there has been evidence to show that mixing is slowing down in some places, and so there isn't anything we can do about it besides stopping climate change. And that needs to happen for many, many other reasons, in addition to just the ocean.

So I think it's safe to say that we need hurricanes for this mixing to occur and to try and even out the temperatures. We just don't want these hurricanes to make landfall and hit people. But hurricanes really are a necessary part of the climate. So we need them. We just if only we could control where they go. Exactly.

So they don't hurt anyone. Yes, I think that is very true. It would be great. It'd stop them from hitting coastlines. Yeah. If we could just get them to disintegrate and just give us a bit of rainfall. Just and mostly we're doing the Oh, I think we're stuck with their destructive effects for, for some time at least. I just want to end with this because I kind of touched upon it.

But we've talked about hurricanes, right? Most of the conversation. But I'm wondering about nor'easters. Could we see something similar with that? Yeah, I know it's a warm core storm as opposed to a cold core storm. But is there anything to point towards those really strong nor'easter is having an impact? One thing that's different about nor'easters is they're happening at a different time of year.

So when hurricanes happening, they're happening over warm water. They're fueled by warm sea surface temperatures in the ocean, whereas nor'easters there happening in the fall and in the winter when the sea surface temperature is much colder. So there isn't that heat at the surface that's getting mixed downwards in the same way that we were showing for our study about hurricanes.

And nor'easters are also happening at higher latitudes. So that just, you know, it's not only the seasonality, but the latitude that, as Sally mentions there, makes it such that there's less heat to move around. However, nor'easters do put a tremendous amount of energy into the ocean that ends up contributing to the mixing of some of those nutrients and oxygen and etc..

So where in in our particular case, we're looking at mixing through the lens of hurricanes and through the lens of the heat transfer. But you can look at mixing through the lens of any other weather system and any other chemical or thermodynamic property of the ocean. And there's there's going to be other interesting stories there as well. Got it.

Awesome. Well, Noel and Sally, thanks so much for the time here. We really appreciate both of you hopping on the podcast. Yeah, we'll look forward to more of your work. And if anyone here listening wants to see their work, you can go to the conversation, You can type in your names and you can see their article again about what we just chatted about today.

Sally Noel, thanks so much for hopping on. Thanks a lot. Thanks so much for having us. Big thanks again to Sally and Noel for hopping on and chatting with us here today. What were you guys as takeaways from this episode and what they had to say about warming and deeper oceans from hurricane? You know, for lack of a better term, it just kind of sounds like a continuous cyclone, right?

I mean, you've got these two hurricanes that come through. They warm the ocean waters down below and and it's something that really can't be stopped. And I think that's what that's something they touched on. And that's something to remember, too, is that they've always been here. Hurricanes have always been a part of our history and that they're important for our ecosystems as well.

You know, to, as she mentioned, to bring oxygen to two parts of the ocean that need them and bring some of that cooler water up to to the surface, it kind of reminds me of wildfires. Yeah, you're right. With wildfires, this has always been a part of the Earth's system. Hurricanes have always been part of the Earth's system.

Right. Long before we were actually here. So on some level, they're big heat engines that that do move heat away from the tropics to the higher latitudes, the mid-latitudes. So they're not going away, nor should they go away. But, you know, we would prefer they stay off of the coastlines whenever possible. Yeah, it really was the the end of the conversation.

You said to me about how central these things are and the importance that they serve. They are they are a huge part of transporting the heat from the equator to higher latitudes. So we need these storms. And yes, so much of the focus is that these things are all bad. And when the storm stays out the ocean, it's it's not a bad thing, you know, and it's easy for boats to go around these storms, especially now that we have satellite technology, it's pretty easy for ships to avoid these storms, unlike in the past.

It's just when they make landfall and the majority of storms do fortunately stay out of water. But it's the ones that hit land that are the problem. So I look forward to the day when we have the power to control the weather many years in the future and we can steer these things away from land and out in the open water.

And then, I don't know, I guess we might be unemployed as we just we wouldn't have to work as I guess we would all be involved in some way and controlling the weather and trying to make everything even across the planet. I, I don't think I'll have to worry about that in my lifetime. But maybe one day we can just keep podcast and that just keep talking and devote more time to podcasts.

We can make it a daily show at that. All right. We are going to wrap it up for this episode. Thanks again to Sally Noel for hopping. I hope all of you enjoyed it. And if you have a question, comment, maybe even a wisecrack for us, you can send us a message via email. Send us an email to podcast at Lee Dot Net.

We have gotten a couple of emails recently. We have answered them in the past and we'll be more than happy to answer them in the future as well as podcasts at the back. For Matt Holiner, Sean Sublette and Kirsten Lang, I’m meteorologist Joe Martucci, we'll see you next Monday on the Across the Sky podcast.

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