El Nino and Nutrient Churning
Audio transcription of earth science lecture on nutrient churning (80% accuracy transcribed)
Introduction to Whale Fall and Oceanic Nutrient Cycles
This whale fall, and it is a decomposing whale. And we can see that. And I think this they said this was like 9000 feet was where they found this particular whale. You see that a number of organisms are feeding off of it. There are microscopic organisms, bacteria that are also feeding off of it. So this is actually a very rich and nutrient rich area of the ocean. It's productive at the surface floor or at the seafloor. But because of upwelling, we can actually draw the nutrients that are being produced. That includes the decomposing matter itself. Other dead organisms, the bacteria, the feces, the and the algae or the the the the bacterial maps that can grow on the floor of the ocean. We can draw that up to the surface where it then can become exceptionally nutrient rich at the surface.
El Niño and La Niña: Discovery and Impact
Now, this is important because it leads nicely into why El Nino and La Nina are such problems. They're not evil or anything like that, but they can be extremely disruptive. So El Nino was discovered about 300 years ago by Peruvian fishermen. Fishing stink. At the time. Thank you. Caused by a reversal in the trade winds. Now, before anyone asks, please don't ask because it's going to be a letdown. And I'm going to tell you anyway. We don't know why this happens. We know what it is. We know that it is a reversal in the trade winds. But I have not been able to find any research that says we know what kicks this off. What causes the reversal in the trade winds? What we do know, though, because we've been observing it for about 300 years, is that it happens at intervals of 2 to 7 years, somewhat similar to the solar cycle. That's on average 11 years. That doesn't necessarily mean that it is every 11 years, but pretty reliably it is. It can go longer and can be shorter than that. The same is true for El Nino.
Upwelling: A Critical Ocean Behavior
Now, again, to review upwelling is a critical behavior of the ocean and brings up those that denser, cooler water that is nutrient rich. Just as a reminder. So this is what nonmetal Nino conditions look like. So we are looking at El Nino effects, particularly the west coast of South America. It all affect us and we'll get to that. But primarily it is happening off the west coast of South America. So in normal conditions, you understand this now we have really cool water off the west coast of South America and cooler water causes air to sink. So we get this high pressure system much, much the same as what we see off the coast of California.
Climate Patterns and Their Global Impact
But out in the western Pacific, along the equator, we get exceptional heating. And this is why Southeast Asia is so tropical and they get a ton of rain in normal conditions. Indonesia is getting a lot of rain because you have exceptionally warm surface conditions that result in low pressure systems, low pressure, rising air, it's unsettled, it causes rainstorms, etc. The trade winds blow towards the equator. They blow toward the low pressure system we've already talked about. Winds go toward low pressure. High pressure pushes air away. And so as a result, what you get underneath the surface is you get this bulge or a bell sheet of warm water underneath this really warm part of the equator. And then what you get as a result of the tradewinds pushing toward Asia is you get upwelling. So you get this cooler water that is brought up into the the eastern Pacific off the coast of the west coast of South America. So this is a normal condition. This is what we want to be happening.
El Niño Conditions and Their Effects
But what we see and this is actually just to illustrate, this is what ocean temperatures look like throughout the year. So you have the Western Pacific, the Eastern Pacific, and you can see that throughout the year, the Western Pacific is very warm. And that usually sends up where we talked about the Kuroshio current. You can see that in the summer that warm water gets very gets into higher latitudes. Now, what happens, however, with El Nino conditions is again, we get a reversal in the trade winds. So remember that the trade winds were blowing toward their eastern release because they were blowing from the east, but they were blowing toward the western Pacific. El Nino reverses those and they become westerlies and they blow towards the east. And what happens is you kind of disrupt that profile of the ocean. So instead of getting this cooler, denser, nutrient rich water brought up near Peru, you actually disrupt it and you get this stratified column of water that is mostly warm at the surface.
Impact on Fishing and Weather Patterns
Now, remember, we're talking about people, fishermen. So if we go back, these are ideal fishing conditions because that upwelling is occurring off the west coast of South America, off of Peru, and it's bringing up that nutrient rich water which draws fish to that area. They capitalized on that and they would use that for their economy, their fishing economy. But with El Nino, it comes in and it completely disrupts that. It pushes the cooler water down to areas. Fish can still survive at these depths, but they're not at the surface where you would presumably be fishing. So we get that warmer water again. You understand that now that we have warmer water that's actually being pushed to Peru, now we get low pressure systems and we get atmospheric pressure falling. Unsettled weather, it becomes wet and rainy and fishing sucks as a result of it or stinks, as I said.
Droughts and Floods: The Consequences of El Niño
If you go to the Western Pacific, though, now we have another disruption. Areas that are typically in non El Nino conditions now have high pressure systems. They dry out. This can affect. Australia. You've probably heard it on the news when they go through these extensive severe droughts and that as a result of El Nino conditions causing a massive area of high pressure to occur on in areas that are typically very tropical and are accustomed to rain and actually need the rain for rice production. So we can see that in both sides of the Pacific we actually have severe disruption to economies.
Weather Patterns and Human Impact
So we talked about how weather affects humans and this is one of them is extremely disruptive to economies in Southeast Asia and economies in South America. It's not even isolated to just those two areas, though we experience here in Utah. We experience El Nino conditions. California is especially susceptible to El Nino conditions. What you see are sea surface temperatures here. And what you notice is that instead of the warmer waters pooling around Southeast Asia like we saw right here, we notice an El Nino conditions that are being forced over here and they even come up as far as Baja, California. So what happens with California is they get this higher temperature water being pushed further up into the latitudes, farther up into the latitudes, since it's literal. And that causes high rain events, lots of precipitation in Southern California, flooding and damage to what seems to be annual burn scars.