Kory and Kellan describe the reasons for, and potential outcomes of, a slowing AMOC (Atlantic Meridional Overturning Circulation). And no, it's nothing like The Day After Tomorrow tries to make you believe.
They also briefly discuss jet streams and the effect climate change has on weather patterns.
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Episode 40 – AMOC and Jet Streams
Kellan: [00:00:00] So Kory I know this isn't necessarily relevant to what we're going to talk about in this episode, but I think it's worth discussing just really quickly. What are your thoughts on this severe mega drought that's hitting the Western United States.
Kory: [00:00:27] Yeah, man, it's crazy. I, uh, I've been kind of watching some different news conferences from different states in the west just to get an idea for what's being said. So there's conferences from California, Nevada, Utah, Arizona. And one I watched recently was talking about how there's all these bans going into place in certain areas like in Nevada, where they're trying to make it so that recreational ornamental grass is outlawed. Other places in Utah they're talking about fireworks bands. They're talking about requiring xeriscaping for new developments. I think they realize that this drought is here to stay and you hear them talk about like, oh, we don't really know, you know, it could rain, it could not. That's out of our control. we don't know what's going to happen next year, but we have to plan and prepare for there not being any water. And it's crazy because they're talking about all these reservoirs, I mean, massive ones like lake Mead, which is at 37% of capacity, Lake Powell wasn't much better.
And we're in June. And most of that water is supposed to last, obviously through not just the summer months, not just June, July, August, but also September, October until it starts snowing again in November and December.
One of the news conferences I watched the governor said, we're transitioning now from doing all those news conferences and press conferences on coronavirus now to the drought. He said, we just go from one catastrophe to the next. And I think that's pretty much what collapses is. Just prioritizing, whatever catastrophe is happening at the moment that's most important and trying to cover it, but we're always one step behind
Kellan: [00:01:59] Yeah. And droughts like that. Don't just happen suddenly one year. The issue is, you know, there's a drought in a given year and the water tables and the aquifers and the reservoirs, like you talked about get to a lower level and then there's drought next year. There's more heat and, and it just compounds. And so I've always heard about cases of extreme drought, but I didn't even know there was a classification above extreme drought. Apparently there's one called exceptional drought, which frankly sounds like it should be celebrated. I would recommend they pick a different term than exceptional.
But I'm just hearing more and more about how much of a crisis it really is. I think most of the west is used to hearing, yeah, things are dry. Ya know, there's some level of drought. But I think like you said, government officials and those who have a responsibility to inform the public or to make policy changes are making it very clear that this is extremely dangerous. And then on top of that, not just running out of water, but the fact that we just came off of a year with the most wildfires in recorded history. I mean, we could see some really scary stuff this summer.
Kory: [00:03:07] Yeah. You know, I've seen this viral tweet going around that shows the drought monitor map from last year in the west. And there's just a couple of little blobs of yellow and light red. And then this year, when the entire thing is just covered in this deep red, and they're saying the one with hardly anything on it at all represents the worst year of fires in recorded history. And here we have this map at the start of fire season, like what's going to happen. And so it is crazy to think about what could happen in the summer. I think we're already starting to see fires this early in the season.
They've been reported already in California, Utah and who really knows. Right. But the conditions sure seem set for a pretty disastrous year.
Kellan: [00:03:45] Yeah. And while we're on the topic, I also think of, you know, some things I've seen around sea ice and that we're at lower levels than we've really ever been. And we talk about in the United States, at least, you know, the West is burning, but we get later in the year and what are we going to see in terms of hurricanes and other dangerous storms? I mean, this is a crazy time in history to be alive.
Kory: [00:04:05] Yeah. It feels like we just got out of the last hurricane season and now we're jumping right into fire season and then we're going to go right into hurricane season again. Yeah. It's absolutely incredible. And what you said about polar sea ice. I mean the Laptev Sea, I saw a chart the other day from Zach Labe. He's a climatologist who posts a lot of really great graphics and yeah, it just shows every year the Laptev Sea, uh, which is one part of the Arctic that borders Russia, is just melting so much faster every year and the lines are getting, it's getting dramatically different. And so it'll be really interesting to see kind of where that leads us this year in minimum sea ice extent.
So speaking of apocalyptic disasters, Kellan, have you ever seen the movie The Day After Tomorrow?
Kellan: [00:04:45] No. You actually asked me that once before and I still have never seen it.
Kory: [00:04:48] Well, boy, are you in luck cause I'm going to play a piece of the trailer for you here.
And that's enough of that.
Kellan: [00:06:16] Wow. Very extreme.
Kory: [00:06:18] Yeah. If that is the future that we have waiting for us, it will be a lot more interesting than I think what really is going to happen. You know, the entire movie is hyper dramatized, over sensationalized, Hollywood depiction of what would happen in the event that the AMOC slows down.
So we've talked about the AMOC very briefly in a previous episode. Today we're going to get into that a little bit more. We're also going to talk about jet streams. And we're talking about the effects that those have on our weather patterns.
Basically while the pace and intensity of the weather disruptions are definitely overblown in the Hollywood depiction of this in the day after tomorrow, the reality is that the slowing of the AMOC and our jet streams and the disruption of their normal patterns will cause severe and intense problems for our societies in the future. Just definitely not at the same pace and in the same timeframe as you see in the movies.
So the AMOC A M O C stands for the Atlantic Meridional Overturning Circulation. Which is a mouthful, but basically what this is, so the theory of how ocean water moves around the earth was originally introduced by an oceanographer by the name of Henry Stommel in the sixties. At that time, they were wondering like, what drives water? Is it just like that the rotation of the earth on its axis? Or like, what is it that's making the water move? So Henry Stonewall hypothesized that water moved around the globe in a complex system of conveyor belts and that the speed and momentum of the moving water was due to a combination of contrasting temperature and salinity. So in other words, cold, fresh water was moving south deep in the ocean, whereas warmer salty water moves north and closer to the surface.
And it does this in sort of a circular motion. Obviously through a more complex system of conveyor belts, but that's the general idea of the AMOC. Again, that's warmer salty water on the surface and cold freshwater deep down below. This is also known as, or called a thermohalene circulation, Thermo being heat and halene being salinity.
So while the oceans are just filled with these conveyor belts, the AMOC is specifically the Atlantic portion and the AMOC provides a ton of benefits to the climate. So for example, the AMOC is the reason that European weather is so consistent and regulated. It's mostly warm and mild. It also reduces sea level on the Eastern coast of the U S as well as helps reduce the amount of hurricanes in the Atlantic.
The currents moving northward are one of the primary distributors of heat around the world, which affects local climate and weather patterns on every continent. So, when you think about how heat moves around, this is one of the primary drivers, it takes the warm waters of the Gulf of Mexico, of the south Atlantic. It moves those waters north, and it takes the colder water from the north and moves it south.
So recent studies showed that the AMOC is currently at its slowest level since at least well over a thousand years. So the rate at which it's pushing that water is just slowing down. Everything's a little more sluggish. And there's been quite a bit of discussion around how accurate scientists can actually be regarding how much it's slowed down, because we've really only been directly measuring the flow since 2004. They basically put a ton of sensors out there, all over the ocean to track how fast things are moving and the temperatures and all of that information.
But just a few months ago scientists released a paper that cited 11 different proxy sources of information, basically different evidence outside of direct measurements to show that the flow of the AMOC is slowing. Those proxies are things like evidence found in seafloor mud, as well as oceanic temperature changes over time.
And that paper corroborates what scientists had already been saying, which is that the AMOC has slowed by about 15% since just 1950. So a pretty significant slowdown in just the last 70 years. In the movie day after tomorrow the scenario is that the AMOC collapses all at once. And basically that causes ,if you've seen the movie, I mean, it's just, there's tornadoes in Los Angeles, like five at a time. There's like 50 foot walls of water that inundate Manhattan and three hurricanes one right after another. And then this massive freeze that just, I mean, it's just ludicrous stuff. Scientists say that while the AMOC collapsing all at once is possible, the most likely outcome is that it will continue slowing gradually over time.
Kellan: [00:10:20] And when you say the AMOC collapsing, you mean it just stops. Things stall out and the ocean water is not moving anymore.
Kory: [00:10:26] Yeah. The current stop, the hot water stays in the south. The cool water stays in the north. There's no mixture of that salty versus fresh water anymore. It just completely breaks down. And they say that even if it did collapse entirely and all at once, we wouldn't see those dramatic apocalyptic storms and things that you see in the movie, especially happening all at once within like a week or two. But that being said, we wouldn't need to see such crazy things happening in order for it to have these disastrous effects on our societies.
Kellan: [00:10:54] Hold on. I've got to just interject mostly because I'm curious about the movie. Like I said, I haven't seen it. Does it somehow end in - everything's okay. And we're happy now. We're starting civilization over again. And the AMOC is cured.?
Kory: [00:11:06] Yeah, it's hilarious. Because the way it ends, they make it seem like it's supposed to be so inspirational. Like it's still got the inspirational music and they're all happy and hugging and looking at each other. but the reason that they're happy is because, um, they're alive and they're flying over Manhattan and they're looking down in the, from these military helicopters and they see people on the rooftops, which signifies to them that there is still some of humanity alive.
And I'm like, okay. So you're about to face the actual consequences of what's happened because the storms and all that crap that's just happened is not what causes collapse in the long run, where are you gonna get your food from? Where are you going to get, you know, all these different problems, obviously they're going to have now, but they made it seem like we're all saved because people didn't die in the massive flood and freezing events.
Kellan: [00:11:52] Man. I've never really had an interest in seeing that movie mostly because I heard some reviews and heard about the ratings, but now I'm actually curious. Now I want to go see it.
Kory: [00:12:01] You are invited to check it out and let me know what you think.
And so the benefits of the mock that I described before begin to destabilize as it slows. That nice, mild, warm weather in Europe? That starts to be replaced by colder weather.
Kellan: [00:12:13] Yeah. And if I can interject again. Here we are talking about wildfires in the U S and it seems like all of our concerns with climate change are the fact that things are going to get warmer and warmer. So I think of the future of Europe is getting really hot and having issues, but you're saying if AMOC slows down or comes to a halt, Europe's going to get cold? Would it just offset the effects of climate change?
Kory: [00:12:36] Yeah, that's a great question. And while I think I could answer that for you. I think it might be more fun to have none other than the day after tomorrow star Dennis Quaid explain that to you for me.
oooooooh Dennis Quaid with the SmackDown! Do you have any questions for Mr. Quaid Kellan?
Kellan: [00:14:36] No all I heard was blah, blah, blah, poor writing, terrible acting. There was something about how global warming can trigger like an ice age.
Kory: [00:14:45] Yeah. So, um, I think that's falsely represented in this movie. The fact that there would be a new ice age because of the AMOC slowing down. That's not at all what would happen, but what would happen, you know, we've, you know, we've used the term global weirding on this podcast before something that Paul Beckwith talks about a lot. And basically it's the idea that climate isn't going to change the same everywhere. And in Europe, for example, their winters are expected to become much colder as the AMOC slows down because like Dennis Quaid just told us the heat that arrives to the earth around the equator from the sun is normally carried north to the north Atlantic by the AMOC where it is then distributed over Europe because of jet streams.
Well, if that slows down, if that warm water stops being carried north, then the jet streams are carrying colder air over Europe, and the winters would likely see a decrease in temperature and the same would be true in other parts of the world with global weirding places. That are cool now will become warmer. Places that are warmer now will become cool. Places where there's tons of rain, it'll stop and places where there. Seemed to be always in drought they'll get too much rain. And the scariest part about that is that it means where there is food grown now it will be much harder to grow in the future. It's terrifying to think about the bread baskets of the world. You know, especially in Europe and the shock that it will be as temperatures drop over time. You know what happens that first time that crops fail for a significant portion of the European continent. It's also terrifying because while the winters and spring will be much colder in Europe, the summers will be much more likely to have heat waves and droughts as well. So everything just gets basically more extreme.
So this isn't just theoretical either. This is something that's happened before. So they believe that throughout history, the AMOC basically is just turned on and off. And obviously it's been gradual and slow over time. It's not like a switch, but it does slow down until it stops. And then it comes back. The last time being just 8,200 years ago when the world was coming out of the last ice age. So not that long ago. Within 10 to 20 years, it had resulted in a dramatic decrease in temperature in the Atlantic ocean. And there's evidence of severe temperature drops across Europe as well.
A couple of other issues with a slowing AMOC on top of the global weirding that we've talked about, storms are supposed to become way more intense over the UK. Hurricanes in the US are going to increase in frequency and intensity as well. You know, as the warm waters that are normally being carried north leading cool waters to the south in the Atlantic, as that slows down or stops, then the waters will become much warmer in the south. And warmer waters are always more conducive to stronger storms. As a matter of fact, the slowing of the mock up to this point is believed to be one of the main reasons why we are seeing an increase in hurricanes in the Atlantic. And why last year was a record breaking hurricane year.
So another big issue with the AMOC slowing down is that, like I'd mentioned before, it helps keep sea level low on the east coast of the United States. But as it slows down, that gradually goes away and the sea level will rise. And it's interesting because it does this without actually adding any new water to the oceans. Normally, when we talk about sea level rise, we're talking about ice melting off of Greenland or from Antarctica. But in this case, no new water is actually added. What happens is because of the way that the earth rotates in the Northern hemisphere water actually deflects to the right. So to the east. As water moves north with the AMOC it deflects slightly to the right and out into the Atlantic.
it's kind of like that whole thing that joke about like the toilets flushing the other way in Australia, in the Southern hemisphere, the water deflects to the left, but as the AMOC slows down and it stops moving that water to the north, it also stops deflecting it to the right or to the east, out into the ocean. And instead that water piles up more along the coast. And we had mentioned in a previous episode about how that's happened in the past when there were some temporary slowdowns with a mock, you know, one winter the sea level rose by a couple of inches in new England.
So the last big impact that we know of that the AMOC slowing down will have is on ocean life. So as temperatures change and salinity increases or decreases, it can change the habitability of those areas for life. And multiple times throughout the podcast, we have talked about how fragile ocean ecosystems are and how tiny changes can have big impacts on those ecosystems. So the slowing of the, a mock would trigger a lot of those sensitivities. And one example of this already happening is in a loss of lobster and Cod fisheries in new England. They've had rapid decreases in their numbers in those fisheries due to these changing environment conditions.
Kellan: [00:19:13] Okay. So you just told me a lot. And it's interesting to hear that there are so many things that would be affected by the slowing of the AMOC. So you talked about weather patterns globally, right? That global weirding. You mentioned Europe getting colder, the UK getting hit by storms, more hurricanes in the U S, sea levels would rise, ocean life would be affected. I mean, I can see why they took it as a good plot line for a movie. But at this point I kind of have my doubts because it sounds like we don't know that much about the AMOC and maybe it's just stuff that you're going to get to. But like you said, there've been times where it has temporarily slowed down and then it sped back up and there's been longer periods of time where it has slowed down and caused an ice age in the past.
So do we know why it slows down and why it later speeds up?
Kory: [00:19:59] We do. And I think there's only one person in this moment that can explain it to you better than I could.
Kellan: [00:20:05] Oh boy.
Ladies and gentlemen, Dennis Quaid.
Kory: [00:21:43] All right, Dennis, we're going to stop you right there. Kellan did you catch what he said about why the AMOC is slowing down?
Kellan: [00:21:49] Well, I heard the dramatic crowd murmuring.
Kory: [00:21:52] They were quite concerned.
Kellan: [00:21:53] Yeah. It sounds like there was a critical desalinization point.
Kory: [00:21:58] Yeah. So a really critical part of the thermalhalene is that there is that balance of saltiness versus freshness, warm versus cold. And so back in the episode that we did about the blue ocean event and sort of the impacts that that would have, that is primarily what's driving the slowing of the AMOC. As polar ice melts, it's infusing an insane amount of cold, fresh water into the north Atlantic. And so now it's creating this imbalance where that lack of salinity and lack of heat is making it so that the AMOC basically loses momentum.
Kellan: [00:22:33] So I feel like I need to cut in here because I've got this question in my mind. Like it makes sense that as more ice is melting, that's adding fresh water to the ocean, but the oceans are so huge, huge, like they cover most of the planet. They're so vast and so deep. And it's hard to imagine that the amount of water that is being added to the ocean, right, fresh water that's coming from that ice melt is enough that it would really change the salinity of the ocean to a degree that it would have this strong of an impact.
Kory: [00:23:04] So, yeah, I mean, the oceans are insanely vast. That is true. But I think that we also underestimate the amount of ice that we are losing and the rate that we're losing it at. In Greenland alone, for example, in 2019, Greenland lost 16,666 tons of ice every second throughout the entire year, that was a million tons of ice per minute. Overall, that was 532 billion tons of ice in the year. Ya know, it's a quantity of ice that's just impossible to even understand or be able to fathom pouring into the oceans. And that's just Greenland. Um, overall they're saying that we're losing somewhere around 1.2 trillion tons of ice every year.
And obviously the oceans are much, much, much bigger than that. But you know, when we're talking about the last 8,000 years, since the AMOC restarted, it's been relatively stable, the amount of salinity and the amount of heat in that water, which is what drives the AMOC has not changed much. And since those are the two primary drivers of the movement and momentum of the AMOC, if you start to change those, then it will make changes to the movement of the water. And, you know, as we said, from the studies that they've done, they believe strongly that it has slowed down 15% in just the last 70 years.
Kellan: [00:24:21] Wow. That's way more ice than I anticipated. But then when you mentioned kind of these temporary blips. You know, you said something about how recently there was a year in which the AMOC slowed down and then it bounced back. What would cause it then to bounce back? In that case, since you're not going to see immediate variability in the salinity of the water, you'd think the salinity would be something that just gradually decreases as more freshwater's added. Is it just that there were crazy temperatures that year?
Kory: [00:24:51] So the long-term trend of the AMOC is it is slowing down. And if you, if you were to look at it on a graph, it would just look like a line that was going down and to the right. But along the way, it might have little variations. And again, those are going to be due to perhaps years with more freshwater being melted or less, maybe variations in temperature in the ocean.
And another thing is that jet streams, so we're talking about jet streams up in the air now, can actually affect the temperature of the oceans as well, based on the strength of those jet streams and where they're located. So the jet streams actually have both a warming and a cooling effect on ocean water. And so as changes in those jet streams intensify that can accentuate the changes in the AMOC as well.
So that actually leads into a kind of a second part of this conversation that I was wanting to have about jet streams. So what jet streams are, they're basically just a narrow band of westerly, wind miles above the Earth's surface. Which by the way, westerly in this case means that they're moving from the west. I think normally when we think of westerly, you would think that you're moving to the west, which is actually the, the normal definition of westerly. But when you're talking about jet streams. Um, those westerly winds means that the jet streams move from west to east.
So there are four main jet streams. There's one at each pole. And then there's one that it's the subtropical jet streams, and those are located between the equator and the poles. The path of those jet streams is dictated by high and low pressures, as well as cool air and warm air. So similar to the AMOC, it basically depends on the temperature of the surrounding area. And then in this case, high and low pressures.
What happens is when there's two fronts that come together, that jet stream gets sandwiched between them. And that drives the wind at which I found out can actually be pretty incredibly high speeds, you know, in the hundreds of miles per hour, those winds move. And typically jet streams are pretty stable. You know, they go around the earth in a circle and they'll meander a little bit to the north and south, but for the most part, they stay pretty consistent. And they're what drives consistent weather and climate in different parts of the world. You know, having consistent jet streams helps us to know where we should plant food, where we're going to have lots of water, you know, areas that are habitable and areas that are not.
but with climate change, different areas of the planet heat more than others. For example, we know that the Arctic is heating at something like three times the rate as the rest of the earth. That is starting to affect the jet stream. So that gentle waviness that we're normally expected to have, has been replaced at times by much larger rises and falls. So it's meandering way more to the north and way more to the south, and it's actually slowing down as well. And so when jet streams do that, that results in things like, you know, snow in Texas capable of knocking out power grids, which we saw earlier this year, and it also contributes to the mega droughts that we're seeing in the west.
And because not only are the jet streams moving further to the north and south, but also because they're slowing down, it means that those storms linger longer. Texas has had cold weather before, but they don't often have freezing cold temperatures that lasts for a week or more. That was one of the most impactful parts of that storm in Texas. And again, the heat waves and drought we're experiencing in the west are elongated because of the slowing of the jet streams.
So anyway, in the end, all of these things result in just additional global weirding. Which is just going to keep making growing food and supply and drinking water more and more difficult.
Kellan: [00:28:08] when you talk about those jet streams, it's a little bit of a paradigm shift for me. Wind just seems like in all cases, it's so intermittent. And so to think that there's kind of this continual stream of air and that wind is constantly moving in certain parts of the planet ya know, I can see how that would be a huge factor in all of our weather patterns. and I'm just imagining the way you described what has changed in the jet streams is you know, if I were looking at like a before picture, I'd see kind of wavy lines, but mostly straight that go in a circle around the globe. And now I'm picturing something more like a zigzag line. And what I'm hearing from you is that those variations in that jet stream, right, to the north and to the south will only get more intense as we see more warming as a result of climate change. And also those can be impacted by the AMOC is that right?
Kory: [00:29:00] So from the research that I did and what I was able to find it's that the jet streams can affect the AMOC not so much that the AMOC has any effect on the jet streams. And so, like you said, the primary reason that there's this increased meandering in the jet streams is because of the temperature changes primarily because the Arctic is heating up so much.
Now I do want to clarify that jet streams are always shifting and changing. You know, from a macro perspective, they're pretty consistent, but it's not abnormal for there to be timeframes where they meander a lot or where they might even split off. And the jet stream kind of splits into two different streams for a little bit. That's what causes, you know, variations in our weather. Cause our weather is not always consistent. But when you look at the macro trend and that's what's starting to change, or when things change, even if it's temporary, those changes are more intense. That's what can really start to cause weather that affects us more severely and as weather changes more and more over time, that's a change in climate.
Kellan: [00:29:56] I've got to say, I really appreciate that you keep using the word meander. sounds like somebody's taking a nice stroll through the park and they might just deviate from the sidewalk for a moment.
Kory: [00:30:06] Just this nice leisurely 300 mile per hour wind going from the north to south miles above the earth.
Kellan: [00:30:13] Ya know all of this is a huge reminder to me just how complex our global system is. Sometimes I think to myself, like, Hey, so-and-so, you're a climate scientist. Why can't you just make some accurate predictions? Like you study this stuff all day. Shouldn't, you know what to expect? Then when he talked about the salinity of the ocean and the temperatures and the AMOC and the jet streams and you factor in pressure and humidity and the amount of solar radiation that is being trapped in the earth by certain clouds and what's being reflected. And, you know, there's so many factors at play. Any sort of a model with that many variables is extremely unpredictable.
And the fact that there are so many things that are interdependent and a change here causes a change in this, which causes a change elsewhere.
Kory: [00:31:01] Ya know, it gives me, I guess a little bit more empathy for those that are trying to give us accurate predictions of what to expect. Yeah, I think the average person goes about their life every day never thinking about, because they don't know about, any of those interdependencies. You know, without having even just a basic understanding of, you know, the way that the climate works and environments work and ecosystems and that type of thing. It's really easy to just take for granted how comfortable we are and how easy we have it. But really everything works only because of those interdependencies. And only because of the insane stability that the earth has experienced over the last. Eight to 10,000 years. And so for people to say, like, it's so egotistical of us to believe that mankind could have an impact on the earth and on climate. That's just crazy to me because we are doing so much and you can see in all of these things that we've talked about, all the different ways in which we are severely interrupting those delicate balances. And we're starting to see the consequences.
Kellan: [00:32:05] Well, I feel like all of this gives me, you know, one more brick in my wall of understanding. It's alarming just to hear some of the facts and figures, and to know that the AMOC has slowed down 15% in the last 70 years. And that alone is concerning. But to me it's just extra concerning because it's one more factor in all of these things that we see coming our way. But Hey, maybe to distract myself from the stress of it all, I'll go rent that movie.
Kory: [00:32:31] I think we'll all look forward to hearing your review in a later episode, once you've watched it.