How The El Nino Is Changing

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Guest Post by Willis Eschenbach

Let me start with a quick run through how mainstream climate scientists think the climate works, and then my hypothesis on how the climate works.

The central paradigm of modern climate science is that changes in the global temperature are a linear function of the “forcing”, the total energy input to the planetary surface. This is generally expressed as an equation:

∆T = λ ∆F

The delta “” means “change in”. The lambda “λ” is a constant called the “climate sensitivity”. “F” is the forcing, in watts per square meter. And “T” is the temperature. So, the equation says:

The change in temperature ∆T is equal to the climate sensitivity λ times the change in forcing ∆F.

Me, I think that’s nonsense. If it were true, the global average temperature would go up and down like a yo-yo on steroids. But it doesn’t. Over the entire 20th century, the temperature increased by about 0.2%. Two-tenths of a percent. And this is despite monthly temperature variations at many locations varying by 30% or more, so it cannot be from “thermal inertia” as many people claim.

My hypothesis is that this temperature stability is due to the thermoregulatory effect of a variety of different emergent phenomena. These include tropical cumulus cloud fields, thermally driven thunderstorms, dust devils, cyclones, and most relevant to this post … the El Nino phenomenon.

The El Nino phenomenon is a curious beast. When the Pacific Ocean gets hot off of the coast of Peru, this is called an “El Nino” condition. It generates extensive winds. These winds blow the warm equatorial surface waters to the west, cooling the ocean surface. This is called a “La Nina” condition. Here is a graphic of a cross section of the ocean looking westward from 90° West, off of the coast of Peru.

Figure 1. 3-D views of the top 500 meters of the ocean, from 90° West (off the Peruvian coast) to 140°E (near the Asian mainland). Left graphic shows the El Nino condition, right graphic shows the La Nina condition. Colors indicate temperature.

In Figure 1, you can see how the wind literally scoops up the warm surface water and pushes it westward clear across the Pacific. Here are two images showing the changes in the sea level during the El Nino and La Nina alterations.

Figure 2. Changes in the sea surface elevation during El Nino (upper panel) and La Nina (lower panel)

Once the warm water arrives at the west Pacific islands and the Asian mainland, it strikes the land and divides in two, with part of the warm water heading towards the Arctic and the rest heading towards the Antarctic. Figure 3 shows the warmer tropical surface water being pushed polewards.

Figure 3. Sea surface temperature anomaly during the 1997-1998 La Nina.

The La Nina wind cool the equatorial Pacific, and thus the planet, in two ways.

First, as seen in Figure 3, it moves the warm water from the tropics toward the poles. There, because the air is dryer than in the moist tropics, more of the radiated heat from the warm water can escape to space.

And second, it exposes a large area of cooler sub-surface water (blue area in Figure 3) to the atmosphere. This cools the atmosphere.

So … if we accept my hypothesis that the El Nino/La Nina alteration is an emergent phenomenon that acts to cool the planet, an obvious question arises—if the earth is gradually warming, will the Pacific shift towards more El Nino conditions, more La Nina conditions, or remain unchanged?

Clearly, if my hypothesis is correct, it will shift towards more cooling La Nina conditions.

How can we measure this? Well, we have several indices that measure the state of the Pacific Ocean regarding El Nino.

The oldest of these is the Southern Ocean Index (SOI), which measures the difference in sea level pressure between Tahiti and Darwin, Australia. The change from El Nino to La Nina conditions affects the atmospheric pressure.

Next, we have the NINO34 Index. This is a measure of the sea surface temperature in the “NINO34” area, which goes from 5°N to 5°S and stretches across the Pacific from 120°W to 170°W. The Niño 3.4 anomalies basically represent the average equatorial sea surface temperatures of an area stretching across the Pacific from about the dateline to the South American coast.

Then there is the Oceanic Nino Index (ONI). It uses the same area as the NINO34 Index, but the ONI uses a 3-month running mean of temperatures.

Finally, there is the Multivariate ENSO Index (MEI). (ENSO is “El Nino Southern Ocean”). Unlike the others, it is calculated from five different variables—sea level pressure (SLP), sea surface temperature (SST), zonal and meridional components of the surface wind, and outgoing longwave radiation (OLR)) over the tropical Pacific basin (30°S-30°N and 100°E-70°W). Because it requires modern data, it can only be calculated post-1979.

To show what is happening with El Nino, I’ve used a LOWESS smooth of the various indices. A LOWESS smooth shows the general trend of a given phenomenon. Here, for example, is the MEI Index along with the LOWESS smooth, and a straight line showing the trend of the index.

Figure 4. Raw Multivariate ENSO Index, LOWESS smooth, and straight trend line. Positive values are El Nino conditions, and negative values are La Nina conditions.

And here is the LOWESS smooth and the trend of all four of the El Nino indices described above. I’ve “standardized” the indexes, meaning I’ve set them all to have a mean (average) value of zero and a standard deviation of one.

Figure 5. LOWESS smooths of four El Nino indices, along with their straight-line trends. El Nino conditions are more positive; La Nina conditions are more negative.

You can see the peaks representing the big El Ninos around 1997-98 and 2015-16. Recall that according to my thermoregulatory hypothesis, the Pacific should be trending towards a more La Nina condition which is more negative.

And all four indices, in varying amounts, show this exact outcome—in response to the slow gradual warming since 1980, we have more La Nina conditions cooling the planet.


Here on the Pacific Coast of northern California where I live, La Nina conditions generally are accompanied by a reduction in rainfall. The last two years have been dry. We’ll see what this year brings, but the good news is that two days ago we got a full inch of rain, and the forest around my house is smiling.

Not only that, but more rain is forecast for the weekend. What’s not to like?

My best wishes to everyone,


OTHER NEWS: I’m still suspended from Twitter. Seems like they must be prioritizing releasing the big accounts from durance vile, at least that’s how I’d do it.

If anyone wanted to send a tweet to @elonmusk advocating for my release, you could reference my post entitled “An Open Letter To @elonmusk” in which I discuss the issues of free speech and so-called “hate speech” … or if not, you just might want to read the post. These are issues of great importance to everyone both on and off Twitter, particularly since the European claim that we should regulate the undefinable category called “hate speech” seems to be spreading to the US.

MY USUAL REQUEST: I can defend my own words and am happy to do so. I cannot defend your understanding of my words. Accordingly, please quote the exact words you are discussing, so we can all be clear on the subject of your comment.

via Watts Up With That?

December 3, 2022

How The El Nino Is Changing — Watts Up With That?