El Niño/La Niña Southern Oscillation (ENSO)

Friday, May 6, 12022 HE

Since getting into stand up paddleboard (SUP), I have become more interested in the weather. From simply checking the forecast to checking the tides to checking the winds to wanting to know what the prevailing pressure systems and fronts would mean for short-term weather forecasts. But like many things that interest me, not only did I want to know these things, I wanted to try to understand them too. And some of my research into wind and global weather patterns sparked an interest in the El Niño/La Niña Southern Oscillation (ENSO). It also helped that there were rumblings of a transition from the El Niño phase to the La Niña phase this past fall/winter.

  1. My Climate Change Rant
    1. The Background
    2. Motivation to Reason
    3. Recent Crazy British Columbian Weather
    4. Denial of Denying
    5. Weather Versus Climate: A Defining Distinction
    6. Anthropogenic Acceleration
    7. The Carbon Cycle: A Brief Foray into Foliage
  2. Eschatology and Existential
    1. Oxymorons and Afterlife
    2. Life’s Catastrophes
    3. The Politics of Unrest
  3. What is ENSO?
    1. Neutral Phase: Walker Circulation
    2. La Niña: Overdrive and Cooler Than Normal
    3. El Niño: Broken Cycle and Warmer Than Normal
    4. But Why? A More Complicated Analysis
    5. ENSO Weather Trends
  4. More On Oscillations
    1. The Indian Ocean Dipole
    2. The Pacific Decadal Oscillation
  5. Weather Models and Butterflies
  6. Armchair Expertise
    1. Migrating Jet Streams and Changing Weather
  7. ENSO Climate Impacts by Phase and Season

My Climate Change Rant

The Background

I first formulated the idea of doing a post on climate change and ENSO at the beginning of November 12021 HE, before the Pacific Northwest floods of the fall. In the summer, a friend had sent me an episode from the TRIGGERnometry podcast “Are We Being Told the Truth About Climate Change? Patrick Moore“, asking for my thoughts as it seemed to fly in the face of everything he had heard about climate change. I was flattered that he valued my opinion assessing the content. Patrick Moore is intelligent and well-spoken. But the fly in the ointment from the get-go for me was that he was going against scientific consensus. In Naomi Oreskes‘ book, Why Trust Science?, scientific consensus is one of the central themes toward scientific credibility and ultimately the truth. Essentially, if many intelligent and educated people believe something, it is likely to be true. This wisdom isn’t foolproof, as history is fraught with examples of smart people believing stupid shit (e.g., Isaac NewtonGalileo GalileiNikola Telsa). And that is where the science enters, as a self-correcting systematic approach to some version of the truth, saving us from drowning in our own BS. I think it is worth noting a quote that I heard from Ed Yong recently, which I will paraphrase as, ‘science is a messy, stumbling, erratic path to slightly reduced uncertainty’. For an excellent lecture and interview with Ed Yong check out this episode of the CBC Ideas with Nahlah Ayed, Edward Yong: The Art of Science Journalism.

The second flag for me from the podcast was that Moore seems to use his credentials as a past environmental activist as a beacon of credibility. I can only speculate about his ultimate motivation, but it smacked of parallels to conspiracy theory. Moore and climate change deniers are privy to some ultimate truth withheld from the unenlightened or uninformed. Again, drawing from Oreskes’ work, including the documentary Merchants of Doubt, part of the playbook for anti-science groups stemming from the tobacco industry is not necessarily to disprove science but rather cast doubt on its veracity.

Motivation to Reason

My overall thought about the podcast was that it was borderline pseudoscientific. Moore presented many verifiable truths, but to me, the conclusions seemed biased. There was an air of motivated reasoning to conclude that climate change is not anthropogenic. I agree with Moore on many of his points. For example, that carbon isn’t inherently bad and that it is essential for life. True. In fact, carbon is the so-called backbone of life and so much more due to its unique chemical bonding properties and abundance on Earth. Or about the irony of the polar bear being the poster animal for climate change, because it is also a prime example of natural selection in a changing climate. True, again. Polar bears are the descendants of the brown bear lineage, which includes grizzly bears.  Fun fact, a grizzly bear and a polar bear can mate resulting in viable, i.e., fertile, offspring often called a ‘pizzly‘. Though conveniently left out of Moore’s narrative is that the estimates of the timescale for this process presently range from 70,000 to 1.5 million years ago. A point that to me is central to the significance of the anthropogenic climate change conversation. Time is crucial. Millions to tens of thousands of years is a big range to be gambling with. As far as I could follow his argument, Moore discredits the anthropogenic basis for the present accelerated rate of climate change. I wholeheartedly disagree with this view. At the heart of climate change is the rate of change occurring under human influence. Are humans unique as a lifeform causing climate change? No. Oxygen-producing photosynthetic microbes and diverse green plants after them changed Earth’s near-surface environment in far more profound ways than humans today. For a short documentary on “How Bad Was The Great Oxidation Event?” from the History of Earth YouTube channel, click the link. Fun fact 2.0 is that the ability of plants to perform photosynthesis is a result of the incorporation of symbiotic cyanobacteria (known as chloroplasts) into their structures. Cyanobacteria are also known as blue-green algae (queue the Eiffel 65! Oh wait … am I the only one who heard the lyrics as “I’m blue, and I would die if I were green, I would die if I were green … “‽). 🤣 Sorry… slightly off kilter there. Let’s get back on track.

The difference with human-induced climate disruption is that microbes took hundreds of millions of years to oxygenate the atmosphere. Evolution at the multicellular life level requires geologic timescales. Something that our present rate of environmental change may not allow. Recent estimates suggest that the current rate of change is 10 to 100 times faster than anything seen in the past. The reason for the wide-ranging imprecision is due to the comparisons being to an era 55 million years ago. The shortest, more similar temperature change of a few degrees occurred over a 20,000-year period, whereas a greater change of more than ten degrees occurred over a period of nearly 20 million years. In any case, on the shorter side of the spectrum, we may experience what previously took as short as 20,000 years in as little as 200 years! For two more balanced listens on climate change, check out “Two (Totally Opposite) Ways to Save the Planet” from Freakonomics and “The Myth of Climate Apocalypse with Michael Shellenberger” from Coleman Hughes.

Recent Crazy British Columbian Weather

The idea for this post developed further after the floods. To me, and I am sure to many, they came as a warning of warming. However, after learning/being reminded that similar floods had happened in the Sumas Prairie previously, I was left wondering how much of the extreme weather was due to climate change overall versus a more proximal shift in the ENSO phase (or some other factor). I 100% believe in climate change. And I wholeheartedly believe that the rate of the present change is anthropogenically driven. But, at the same time, weather and climate change are two different things, and I believe it is worth asking which of the two was more responsible for the weather we witnessed.

Could the extreme weather that we had here in British Columbia result from the change to the La Niña phase? Or were they the result of larger-scale trends? A shift in overall climate resulting in proximal weather extremes and possibly a premonition of pending patterns of atmospheric pressure permutation?

In 12021 HE, two extreme weather events occurred that nearly all British Columbians will be familiar with. They also made international news headlines. In the summer, Lytton, a village in southern British Columbia’s Thompson-Nicola region, experienced a record-breaking heatwave or heat dome. On June 29 the temperature in Lytton set a Canadian all-time-high temperature record of 49.6 °C (121.3 °F) and made international headlines. For context, the previous record high of 45.0 °C (113 °F) was set in 11937 HE during the dust bowl era drought engulfing the North American Great Plains. The record temperatures were recorded in Yellow Grass and MidaleSaskatchewan. Tragically, the following day, Lytton would make international headlines, yet again for a wildfire that razed the village, killed two civilians, caused an estimated $78 million in damage, and traumatized many. A later coroner report would later implicate the deaths of nearly 600 people to the heat dome.

Then later, in November of 12021 HE, British Columbia, would experience record-breaking levels of rainfall across various locations. An atmospheric river resulted in extreme amounts of precipitation deluging the Pacific Northwest. Over two days, November 14 and 15, the Hope district municipality received 277.5 millimetres (10.93 in) of rain. The rainfall almost surpassed the standing two-day provincial record of 303.6 millimetres (11.95 in) set from November 9 to 10, 11990 HE. The rainfall resulted in widespread damage (estimates of the property damage are $2.5-7.5 billion) and at least five casualties throughout the province. The Sumas Prairie flooded, paralleling the results of the 11990 HE record rainfall, which was the last time the former lake bed flooded. All this left me wondering what the ENSO phase was for the fall/winter of 11989-11990 HE? But, from what I can discern, it appears that it was a neutral phase of the oscillation (Government of Canada 4; “La Nina – 1988 – 1989”; Trenberth and Hoar 1).

As discussed later, I will armchair speculate whether these extreme weather events result from ENSO, climate change, or a combination. I have no expertise in the area.

As I assume is the case for many, the first that I can recall hearing about ENSO was concerning poor weather. At the time, from memory, it was only El Niño that was referenced. My understanding then was that El Niño was responsible for tropical storms that we received in the Pacific Northwest. While that may loosely be true, my current understanding of ENSO is that it is a much broader and nuanced phenomenon.

Denial of Denying

I am in no way a climate change denier. Does that set off alarm bells? Writing it now does for me. I feel that denying being a denier is never a sound opening to a constructive argument. It feels like the language a closeted denier would use to open their position. For example, I am not a racist but… , I am not a sexist but… , I am not a climate denier but… , etc. After this opening clause, a cringing account of attempted exoneration ensues. To which the listener only finds that the argument supports the counterfactual.

So let me attempt to clarify where this is going. What then becomes my but? I think there is indisputable evidence that the climate is changing with time. But everything is changing. That in and of itself does not mean that we are in a new era of climatology from a geological time perspective. The argument becomes tautological in that regard. The climate has forever been changing and, in all likelihood, will continue to change.

Weather Versus Climate: A Defining Distinction

I recall watching Cosmos: A Spacetime Odyssey with Neil deGrasse Tyson when he describes the difference between climate and weather by using the analogy of a dog walking on a leash. The dog walker, deGrasse Tyson, takes a more or less straight path, while the dog is left to deviate the length of the leash from the dog walker’s path. In the video clip, Neil deGrasse Tyson coaxes the dog from side to side to illustrate the distinction between climate and weather. The trajectory that deGrasse Tyson takes is the climate. It is the overall trajectory or trend. Contrastingly the more random and varied path the dog takes is the weather. The weather exhibits more fluctuations. But, the weather is bound by the climate. The analogy is apt. However, for many of us, I think we conflate the two. Since our objective perception of the meteorological phenomena around us is the weather we live through, that is what more readily comes to mind. But that negates the systematic trends and is easily confounded by the ephemerality of our memory. I can hardly remember the weather from a few days ago. Let alone recall the weather of past weeks, months, or years. Try recollecting the trends in what the climate has done, and it is next to impossible. Both because what we tend to experience and remember is more akin to weather and the time scale at which the climate changes are geologic, not anthropologic. We have to default to experts and systematic methods of inquiry, i.e., modern science, for objective and accurate interpretation of the weather. And on a larger scale, climate change.

Anthropogenic Acceleration

In this regard, I believe that the evidence for anthropogenic climate change is also indisputable. The experts have shown through multiple layers of evidence and analysis that the change in greenhouse gases correlates with the industrial revolution and the use of fossil fuels to power our progressHas the climate changed without anthropogenic influence in the past? Of course, it has. And it will continue to in the future. Climate change was a thing in the past resulting from geological (e.g., Paleozoic era and the aptly named Carboniferous period) and cosmological (e.g., Chicxulub crater, which was the meteor that took out the dinosaurs) events. The difference is that in the Anthropocene, humans have accelerated the rate of change. The rates of change appear to have reached levels that we do not believe occurred in the past. Watch the video below, “The Past We Can Never Return To – The Anthropocene Reviewed“, by Kurzgesagt. It is an animated narration of a story from John Green‘s podcast, The Anthropocene Reviewed. The podcast is now on my listening list.

The rate of climate change is a defining characteristic of the Anthropocene. We are layering environmental changes on top of more natural geological processes. I emphasize “natural” here because, in my view, humans do not exist outside of nature, as is often taken to be the case. As if we are an animal that is different from all the rest and exempt from natural laws. I acknowledge that humans are different from many other animals in our capacity for complex cognition. But in my mind, nature is the outcome of how the universe unfolds. We are witnesses and active participants in the unveiling of the nature of the cosmos. Not some supernatural species safe from the scourge of the Source (i.e., Mother Nature). Below is another video featuring John Green from his channel Crash Course on “The Anthropocene” from their Big History playlist.

The Carbon Cycle: A Brief Foray into Foliage

Furthermore, anthropogenic climate change also passes the that just makes fucking sense test for me. Very scientific, I know. The climate changed in the past, when large amounts of carbon were either released or captured (for more on The Carbon Cycle click the link). Think about the trees that surround you. It seems like a simple question, but often people get it wrong. Where does a tree get its mass? Like, what is tree stuff? Dirt? Water? Minerals from the soil? See the video below from Veritasium for the answer if you don’t know or are unsure.

Trees are a massive reservoir of carbon. Trees first appeared in the Devonian Period, approximately 420 million years ago. And if you follow the timeline on this page, you see a drop in the estimates of atmospheric carbon around this time. It is no coincidence that the Carboniferous Period, around 360 million years ago, follows the Devonian. Carboniferous literally means “coal-bearing”, from the Latin carbō (“coal“) and ferō (“bear, carry”). It refers to the many coal beds formed globally during that time. Atmospheric carbon was captured in the plants of the time by harnessing solar energy via photosynthesis to build carbon-based structures. It is believed that trees’ development of bark at this time and the presence of swamps created the conditions for the coal beds to be formed.

Eschatology and Existential

So then, what’s my but? Where my views become less mainstream, at least from what I gather in the generalized climate narrative, is that I am not convinced that climate change is an existential threat to humanity. At least not in the way of the popular culture portrayal. And this may stem from semantics. When I think of “existential”, the literal dictionary definition of ceasing to exist comes to mind. Now, while I, nor anyone, cannot guarantee that climate change will not be the existential threat, I do think that it is less likely when compared to other existential threats. I will preface that by acknowledging that climate change will not be without catastrophic consequences for particular individuals and communities. Thus, climate change is something that we should address as a collective species. It very much parallels the coronavirus pandemic in my mind. On an individual level, contracting Covid-19 generally does not pose a significant threat. You are more likely to survive the infection across all demographics than die. But, some people will still be the unfortunate anomalies in that probability. However, at a population level, the pandemic posed and poses a much more significant threat. Unmitigated, the pandemic had the potential to collapse our modern healthcare systems, resulting in mass morbidity and mortality. Thankfully, that was not the case generally, though again, it was not without incident for many, but not most. In a similar parallel, in my mind, we managed to mitigate the effects of the pandemic through our behaviours. The effects of what could have happened without a coordinated response are unknown but undoubtedly would have ended with more morbidity and mortality. We can only hope that the same is true for anthropogenic climate change.

I will hedge my argument with a caveat. Barring anthropogenic annihilation by cosmological catastrophe, at a geological time scale, climate change will.

Oxymorons and Afterlife

With respect to the threat of climate change, you could invoke a sort of Pascal’s Wager scenario here. A failure to act on climate change due to a disbelief in the existential threat posed may ultimately result in existential catastrophe. In the case of Pascal’s Wager, it suggests that you are better off living your life as if God exists. Because if God does exist, you stand to gain infinitely by gaining access to heaven and an eternal afterlife. Whereas you only stand to suffer finite losses in the present life by leading a pious lifestyle. Comparatively, living an impious/sinful and arguably, more hedonistic life would give you finite gains in the here and now at the expense of infinite losses via an eternity in hell.

The climate change crisis could run along similar lines. You’re better off running the end game scenario as if it does exist since the consequence of not believing it does outweigh the small(er) inconveniences of living a life in which you do believe it does. The problem for climate change is however (multi)generational and transnational/continental. Those who stand to bear the brunt of the effects of climate are not the same people as those who bring the cause of climate change. Time, in the transgenerational content, rears its head again in the anthropogenic climate change conversation.

As a side note, I have always found the concept of an afterlife perplexing and oxymoronic. Perhaps life after death is a more apt way of putting it. If there is going to be a life after death, what is the point of the present life? It seems unlikely to me that life would be iterative. Philosophically, I believe life is meaningless. I suppose I am an optimistic nihilist to put a label on my beliefs. There is no greater point or meaning in my mind. Aside from a peculiar set of circumstances that allowed the physics, chemistry, and ultimately biology of the cosmos to come together in emergent ways to give rise to complex, intelligent, and conscious life (for more on emergence, watch this video on how stupid things become smart together). This complex interaction between intelligence and consciousness allows our lives to become philosophically introspective. In my mind, there is no greater or ultimate purpose or meaning. The meaning of life is what we make it. What would be the point of having a qualifying life for another, later layer of living? That is nonsensical. Obviously, if you believe in a karmic reincarnation or a meritocratically earned heaven and hell, this current life is of great import. And that, in my view, is where the idea of an afterlife arises. The concept of the afterlife arose from a human cognitive tactic to deal with the emotional emptiness that results from a realization/understanding of eternal oblivion after death. To me, a belief in an afterlife becomes a convenient consolation to deal with the desolation that someone might experience with the realization of the pending eternal oblivion. In a Buddhistic sense, emotional suffering only results from a desire for the unattainable. That is the desire for eternal life. If there is no desire to live forever, death no longer becomes something to avoid. I am not saying that I want to die, but rather that I accept the inevitability of my eventual demise.

At the same time, I also think that a belief in an afterlife is a comforting way to memorialize loved ones that have come and gone. Believing that they have gone on to a better place or a pending reunification with them in the afterlife is comforting cognition. Ironically, in my mind, I do believe that we reunite with our loved ones upon death. But not in the same way many afterlife believers see it (at least how I think that they see it?). In my cosmological view, we are manifestations of energy. Fluctuations in an energy field result in strange properties that a higher level of emergence ultimately gives rise to our experiences. And so, when we die, our energy is redistributed back into the cosmos under the laws of thermodynamics. So in that sense, we are rejoined with our loved ones. When our life ends, entropy overtakes our capacity to resist the complete dissipation of our life energy. We lose the emergent property of consciousness, and our experience of self disappears into oblivion. The video below is an excellent explanation of this concept and helped me elucidate the idea in my own mind.

Life’s Catastrophes

Enter the semantics. If your definition of existential threat to humanity means humans cease to exist, then I don’t believe anthropogenic climate change is the existential threat. As in species ending. Will climate change be catastrophic to humanity? Here, I think there is a much higher probability. And, undoubtedly I believe that climate change will ultimately be catastrophic for many. But, in my mind, catastrophic and existential crises are not the same. And I am not the only one making this distinction. “Catastrophic” to me connotes a proportion of the population, whereas existential suggests the entirety. Both are not great, but one is definitely worse.

I recall reading Bill Bryson‘s A Short History of Nearly Everything and being shocked reading Chapter 13, “Bang!”, that we would be largely unaware of a space rock approaching the Earth until it was too late! And that many space rocks large enough to cause serious damage regularly pass by the Earth largely unnoticed. Essentially, it boils down to no one looking for these objects. And for the few people that are, the means of detecting them is low. It reminds me of a podcast where the interviewee, an astrologist, tells the story of heading to a conference about the soon to closely-pass-Earth micro-asteroid, Duende. I couldn’t find the podcast, but here, “These are the asteroids to worry about“, is the same story by Veritasium. To the surprise and embarrassment of the conference attendees, the Chelyabinsk meteor crashed into Chelyabinsk, Russia. None of the attendees had any prior knowledge of the meteor’s pending arrival. And there is at least one past precedence that most of us are familiar with regarding a space rock resulting in an existential crisis. To the best of our knowledge, the dinosaurs were more or less wiped from the annals of history when a 10 to 15 km (6 to 9 mi) wide comet or asteroid crashed into the Gulf of Mexico‘s Yucatán Peninsula approximately 66 million years ago. The impact scarred the Earth with a 180 km (112 mi) crater, Chicxulub, and sparked the Cretaceous–Paleogene (K–Pg) mass extinction event and left the K-T Boundary as evidence. All this is to say that my worry of an existential threat to humanity is more celestial than terrestrial (check out “The Map of Doom | Apocalypses Ranked” from DoS – Domain of Science for a visual and statistical estimate: WARNING not for the prone to existential dread). Though it is worth noting that the dinosaur extinction created the opportunity for mammals to flourish. A real-life Phoenix, rising from the ashes or an ouroboros life cycle of life arising from death. To really challenge your existentialist preconceptions, check out the End of the World with Josh Clark podcast. For an entertaining and informative listen on the asteroid impact, check out Radiolab‘s Dinopocalypse.

A small note of a CYA here. The flagship five previous mass extinction events have all included some form of climate change. The environment needs to change enough to be unhospitable. The climate changed. So, I am not so foolish as to suggest that climate change will not factor into the probable existential demise of our species. On the contrary, I think it most probably will. What I am surmising is that anthropogenic climate change will most likely not be the cause of the end of humanity’s existence. I believe it will come at the behest of a more natural process/event. But I am completely willing to concede that perhaps my conception of the crisis is way too facile and I am missing the geological magnitude of our current situation from a much too simple anthropologically oriented timeframe. I guess I am banking on the anthropogenic process taking enough time that it will be engulfed by another more cataclysmic event.

The Politics of Unrest

Where I do see more plausible outcomes resulting in an existential-like crisis is how we collectively respond to the threat of climate change. A historical example of this is the collapse of the Mayan empire. A mix of political and environmental problems is often blamed for the decline of Mayan cities. The geological data obtained from lakebed sediments and speleothems tells the story of drought (for more details, here is a great listen on the topic from the BBC‘s Crowd Science). While we will never know exactly how the environmental changes affected social and political processes in the Mayan civilization, we do know that a sophisticated society that flourished for millennia came to an end. Obviously, since the collapse of the Mayan civilization, our level of knowledge and technology has drastically improved. I don’t see drought as such an unmanageable risk present day. Though, I say that from a place of privilege as I am aware that a quarter of the world’s population lacks access to safe drinking water. So the Mayan example does serve as a warning of possibility.

There is no doubt in my mind, that climate change will result in even more climate refugees as droughts and famines take hold at the local level. Environmental disruption will continue destabilizing regional and global geopolitics via mass migrations and conflict. For an excellent discussion on mass migration, check out Jennifer Welsh‘s third 12016 (HE) CBC Massey Lecture, “The Return of Mass Flight“. It is part of a five-part lecture series, “The Return of History: Conflict, Migration, and Geopolitics in the Twenty-First Century“. It is a reappraisal of Francis Fukuyama‘s 11989 HE essay The End of History?, and well worth a listen (or read as the lectures are available in book format). Fukuyama suggested that Western liberal democracy may be the endpoint of our political evolution. Welsh questions Fukuyama’s argument given the recent history leading into 12016, filled with terrorism and war, rising inequity, and the mass flight of populations. She suggests Fukuyama’s pronouncements about the “end of history” may have been premature. 

You only need to look to the present, and the current anthropologic geopolitical disruptions look even direr. Vladamir Putin‘s 12022 HE fatuous and evil invasion of Ukraine will have deleterious consequences for food and energy security outside of the immediate conflict zone. That will be particularly evident for African and European nations, respectively. And it goes without saying that the atrocities the Ukrainian people are suffering and will continue to suffer if the conflict does not end are horrific and unnecessary. Not to mention everyday Russians, as this is Putin’s war, not theirs (though that opens the discussion of epistemic responsibility and what is the moral obligation of a society). With geopolitical, economic, and environmental implications of fossil fuel consumption front and centre via war, inflation, and climate change, we appear to be at a grave moment.

I am currently reading Helen Thompson‘s Disorder: Hard Times in the 21st Century. The first part tells the history of oil and how attempts to achieve energy security have formed the geopolitical landscape since the time of the Robber Barons. It is a timely read. It does feel like we are tenuously balanced at a moment of existential crisis. I suspect (perhaps hope) that only the latter is true, that we are in crisis. But I do not believe it is an existential one. Rather than our existence in question, I would contend that it is more our identity. As best we can be represented as a collective species, what is it we want? What is our collective life’s purpose? To the extent that we can influence our trajectory within the physical confines of the cosmos, what our purpose or meaning is, is what we want, in my opinion. Whatever we want it to be (until we are rocked by a massive space rock or another cosmic existential crisis strikes).

But I digress … back to ENSO.

What is ENSO?

As the name suggests, ENSO, the El Niño/La Niña Southern Oscillation, is a climate phenomenon that oscillates. It involves changes in ocean and atmospheric temperature and pressure that fluctuate between three phases, El Niño, La Niña, and neutral. To better understand the mechanisms behind ENSO, it is a good idea to know a few weather basics first. The United Kingdom‘s national weather service’s (the MET Office) three-part video series on “What is global circulation?” (Part One: Differential heating, Part Two: The three cells, and Part Three: The Coriolis effect & winds) is an excellent resource that covers the basics. Here is the post from the MET office if you want the text summary instead. The differential heating of the globe, coupled with the cell systems and the Coriolis effect, results in the redistribution of the Sun’s solar radiation (i.e., heat) around the Earth. These processes are the source of the trade winds, easterly winds near the equatorial region (i.e., blowing from the east towards the west; check out this post on “The Four W’s” for a more in-depth explanation). And the anti-trade winds, or westerlies, in the middle latitudes. The prevailing trade winds drive the Pacific Ocean surface water westward and are a driver of the ENSO. But, it is a complicated dance where one partner responds yet simultaneously affects the other.

Neutral Phase: Walker Circulation

The neutral phase of ENSO is the baseline Walker Circulation pattern. The trade winds move warm air and water to the western Pacific. Here, the warm moist air rises and will often form cumulonimbus clouds, resulting in rainfall. The now drier air travels east, descending over the cooler eastern tropical Pacific. The the same time, the movement of warm water westward creates the equatorial thermocline the results in an upwelling of cold water in the eastern Pacific along the western coast of South America. The pattern of atmospheric movement shown in the diagram below by the grey line is Walker Circulation. The corresponding oceanic movement to the atmospheric Walker Circulation is depicted by the white lines.

La Niña: Overdrive and Cooler Than Normal

La Niña is essentially an intensification of the neutral phase. Stronger trade winds result in more warm water accumulating in the western Pacific and more convection (see below).

El Niño: Broken Cycle and Warmer Than Normal

Whereas El Niño, the warm phase of the oscillation is essentially a breakdown of the Walker Circulation pattern. The trade winds weaken or may even reverse, which allows the warm surface water that normally accumulates in the western Pacific to move into the central and eastern tropical Pacific Ocean.

Since the Pacific Ocean is the largest body of water on Earth, changes in the location of its warm water have both local and global effects. For an overview with visuals, check out the videos below. The first one is on El Niño and the second one covers both El Niño and La Niña. They are North Americentric, so if you are like me and are near the Pacific Northwest, they provide more insight into your local weather and climate patterns.

But Why? A More Complicated Analysis

Here are a few more takes on the ENSO phenomenon. “El Nino – What is it?” is from the UK’s MET Office. For a more Austroasiacentric take, check out “Understanding ENSO” from the Australian Government’s Bureau of Meteorology (BOM). And if you want to go really deep, check out this video from But Why? on “What Causes the El Niño Southern Oscillation?

I found the But Why? video particularly interesting because it lives up to its eponym. You can think of the ENSO as a yo-yo-ing global air conditioning system that turns on or off, depending on if the western Pacific becomes too hot or cold. The question then becomes why or how does the system turn on or off? I found the two hypotheses as to what drives the change in the oscillation fascinating. In particular, the inclusion of Rossby and Kelvin waves in the explanations. In the Harmonic Oscillator hypothesis, the Rossby waves are reflected from the landmasses in the western Pacific. The reflected waves reduce the thermocline and shift the build-up of warm water to the central Pacific. The hypothesis is that noise in the system (i.e., fluctuations in atmospheric pressure) ultimately causes the oscillation. In the Stochastic hypothesis, the model suggests that the neutral phase is a stable state. But, the unpredictability of nature again results in a change from a steady state, resulting in slippage or breaking away of the neutral phase’s warm western water body. As noted in the video, these two processes may ultimately be the same. For another take, read this article from the Weather Network on “What is La Niña? And how does it impact global weather“.

Below is a schematic from the National Oceanic and Atmospheric Administration (NOAA) of the typical impacts of La Niña on North America during winter.

The comparison below shows the typical climate impacts of El Niño and La Niña for the northern hemisphere summer (June to August). Move the cursor bar to the left to see the trends for La Niña. And move the cursor bar to the right to see the trends for El Niño (for a non-scrolling comparison and larger legend, see the images side-by-side here).

Typical climate impacts of El Niño and La Niña from June to August. Move the cursor bar to the left to see the trends for La Niña and to the right for El Niño.
Source: https://www.climate.gov/news-features/featured-images/global-impacts-el-ni%C3%B1o-and-la-ni%C3%B1a

The comparison below shows the typical climate impacts of El Niño and La Niña for the northern hemisphere winter (December to February). Move the cursor bar to the left to see the trends for La Niña. And move the cursor bar to the right to see the trends for El Niño (for a non-scrolling comparison and larger legend, see the images side-by-side here).

Typical climate impacts of El Niño and La Niña from December to February. Move the cursor bar to the left to see the trends for La Niña and to the right for El Niño.
Source: https://www.climate.gov/news-features/featured-images/global-impacts-el-ni%C3%B1o-and-la-ni%C3%B1a

More On Oscillations

The Indian Ocean Dipole

In my research of ENSO, I came across two other weather phenomena that add nuances to the narrative. The first is the Indian Ocean Dipole or IOD. Think of this like ENSO’s little cousin. It is also an irregular oscillation in the temperature and pressure differences across an ocean and the atmosphere, this time in the Indian Ocean. The IOD is defined by the difference in sea surface temperature between a western pole in the Arabian Sea (western Indian Ocean) and an eastern pole in the eastern Indian Ocean south of Indonesia. The ENSO and IOD are believed to be linked through an extension of the Walker Circulation to the west and associated Indonesian throughflow (i.e., the flow of warm tropical ocean water from the Pacific into the Indian Ocean).

Positive IOD events are often associated with El Niño and negative events with La Niña. Scroll the image below to see the trends between the positive and negative IOD phases.

Scroll left or right to see the Negative or Positive phase of the IOD.
Source: https://www.climate.gov/news-features/blogs/enso/meet-enso%E2%80%99s-neighbor-indian-ocean-dipole

If the IOD and ENSO are in phase, the impacts of El Niño and La Niña events can be more extreme. Check out this video from the Australian BOM for another overview of the IOD and examples of IOD/ENSO couplings. Whereas, if they are out of phase, the impacts of El Niño and La Niña events lessen. Amazingly, this phenomenon was only first identified by climate researchers in 1999. Though, I suspect that similar to human historiography of ENSO, the indigenous understanding or at least observation of the IOD phenomena may be older.

The Pacific Decadal Oscillation

The second phenomenon I encountered is slightly more controversial, the Pacific Decadal Oscillation (PDO). The PDO simplified is like a longer-duration version of ENSO. Rather, than oscillating closer to a yearly scale, as in ENSO, the PDO spans decades. It oscillates over 20-30 year cycles.

During the positive phase of the PDO, sea surface temperatures are similar to El Niño, with warm waters in the eastern Pacific along the western coast of the Americas. The difference is that in the PDO positive phase, the warm waters extend further northwards along the western coast of North America, creating a horseshoe-like pattern (see image below). The negative PDO phase is more similar to La Niña, and resembles the image below with the colours reversed.

Weather Models and Butterflies

The controversy surrounding the PDO is that it has been used by climate change deniers to dismiss climate change. In the early 12000s HE, the global rise in temperature was less than what the climate models of the time predicted. Some people took that to mean that the increase in global temperature had slowed or stopped. Another explanation would be that the PDO caused an anomaly, that was not accounted for in the climate models of the time (more on predictability later). Science is by no means a perfect process. But unlike faith-based beliefs, beliefs based on science are more apt to change. The scientific method is an iterative or cyclical process whereby new or conflicting information can change the current paradigm. Sometimes that shift is seismic, and other times it is subtle. For example, when Alfred Wegener first proposed the theory of plate tectonics in 11912 HE, it was controversial and widely rejected (check out “The Whole Saga of the Supercontinents” from PBS Eons for more details on plate tectonics). It wasn’t until the 11950s HE, that the mainstream geological community began to embrace the theory. It is worth noting the distinction between a scientific theory and a theory in the colloquial sense. The former is an explanation of a natural world phenomenon based on testing and evidence. Whereas, the latter is an untested hunch or guess. Along the same lines, a model in the scientific sense is “a physical and/or mathematical and/or conceptual representation of a system of ideas, events or processes” (“Scientific Models”).

The irony here is that, to the best of our knowledge, our brains function as a prediction machine for our experience of reality. That is to say, our brains model reality. For example, when we see something, what we perceive is a sort of optical illusion of our mind. As best we can tell at present, the reality of what that something is when we see it is an excitation of energy receptors in our eyes that transfer energy through our nerves to emerge as an experience of an object. The energy exciting our receptors, visible light, are photons that cause fluctuation in the electromagnetic field (bear in mind visible light is only a fraction of the electromagnetic spectrum and there are a bunch of wavelengths were are blind to, i.e., radio wave, microwave, gamma ray, etc.). Most people are familiar with the duality of light. Light is both a wave and a particle. But, at the same time light is neither a wave nor a particle. Light is a vibration (or excitation) in the electromagnetic field. Below are two excellent videos that simply explain these concepts, what is stuff or reality and what is light. Watch this video, “Understanding Light and Why it exists“, for a more detailed explanation.

Source: https://cdn.britannica.com/75/95275-050-5FC96002/Radio-waves-rays-light-gamma-ultraviolet-electromagnetic.jpg

So the next time you hear someone making light of climate change predictions saying they are just models, you can snicker to yourself. Maybe the climate models are wrong, but maybe, the model in their head is too. Or perhaps better stated, their interpretation of their model may be in error. The other piece to this story comes down to chaos theory or what people colloquially know as the butterfly effect. This can be summarized by the three-body problem, where despite having the initial positions and velocities of three-point masses, solving for their subsequent motion as a closed-form solution is impossible. A must-watch on this topic is, “Chaos: The Science of the Butterfly Effect” by Veritasium. The reality is that a climatologist’s prediction of the weather or climate is impossible to make accurately. As time passes in a prediction model, the inaccuracy grows. However, the modeller is aware of this and can deal with the error range via probabilities. I am not sure this is the case for the average predictive model naysayer.

Armchair Expertise

Time for some armchair philosophizing. How much of a role did ENSO or climate change play in the extreme weather events (heat dome and flooding) that we experienced in British Columbia in 12021 HE? First off, I would venture that the two events were, to a degree, related. At the risk of being laughably wrong by conflating correlation with causation and confounding memories, I recall thinking about past instances of flooding post-fire and drought during British Columbia’s heat dome. From memory, it seemed that past years of bad fire seasons coincided with flooding (e.g., in Alberta, Australia, and California). In drier conditions, particularly after severe fires, the soils in forest landscapes become hydrophobic (i.e., they repel water). At the time of the heat dome, I was worried about what the spring of 12022 HE would have in store when the spring melt-off and rains would compound with the scorched earth. I didn’t anticipate the effects to be in the fall of 12021 HE.

Migrating Jet Streams and Changing Weather

When learning about the jet streams, I came across the video below. It provides a convincing explanation of how changes in the jet stream stemming from climate change may have caused the heat dome experienced in British Columbia (as well as the Texas deep freeze and stagnated Hurricane Ida). One of the effects of climate change is that the Earth is warming faster at the poles than anywhere else. As discussed above, the jet streams are part of the global circulation system and depend on differential heating, the three cells, and the Coriolis effect. With the poles warming faster than subtropical and tropical zones, the temperature gradient across the polar jet stream is less. The warming weakens or slows the jet stream. Recently it has been hypothesized that the slower jet stream may result in slower-moving weather systems and a wavier jet stream. These are our good old friends, the Rossby waves again, this time affecting the polar jet stream. In the image below, the sequence depicts the polar jet stream getting wavier with Rossby waves in subsets “2” and “3”. The sequence shows how a polar low-pressure cold air mass can break away from the polar region to the subtropics.

In the case of some extreme weather events for 12021 HE, one hypothesis is that the jet stream underwent extensive buckling. In the case of the Texas deep freeze, the jet stream buckled, allowing a polar air mass to reach Texas. And in the case of our own Beautiful British Columbia, a continental tropical air mass travelled to the subtropics and was held there. For more details and visuals, see the image and video below.

So, my armchair-authority-assessments suggest that it is plausible that the heat dome was related to climate change. The decreased temperature gradient across the polar jet stream may have slowed it down, creating conditions that would allow the tropical heat to travel north. At the same time, the NOAA’s post, “What is a heat dome?“, directly relates the creation of heat domes to La Niña. The post states that scorching heat is ensnared, “when strong, high-pressure atmospheric conditions combine with influences from La Niña, creating vast areas of sweltering heat that gets [sic] trapped under the high-pressure ‘dome.'” (US Department of Commerce, National Oceanic and Atmospheric Administration). Where things don’t necessarily add up on the armchair musing weather front, is that most climate change predictions suggest that local trends are amplified. Hotter and dryer regions will become hotter and dryer and wetter regions will get even wetter. But these are trends, and as we saw with chaos and the butterfly effect, the trends are impossible to predict precisely. So, my amateur-armchair-assessment verdict is that both climate change and ENSO contributed to the heat dome.

Concerning the flooding, the heat dome was already implicated, due to its role in creating hydrophobic soil conditions. Climate change and ENSO are guilty by association. The hydrophobic soil environment sets the stage for too much run-off in the event of rain. But you still require rainfall. If you are a British Columbia resident, you are probably already familiar with atmospheric rivers (e.g., pineapple express). As the name suggests, atmospheric rivers are moisture-laden waterways that travel through the sky. Atmospheric rivers are nothing new in weather science other than presently there is a greater understanding regarding them. The question from my armchair then becomes, is there any evidence that atmospheric rivers are more intense or frequent due to the ENSO phase or climate change? While there doesn’t appear to be a proverbial smoking gun, there is at least speculation that either or both may be at play. And that’s enough to persuade my armchair expertise.

In fairness, I am well aware of my sampling and confirmation bias here in that I am searching for evidence to support my viewpoint. For example, the ENSO phase when the Sumas Prairie last flooded appears to have been neutral. This fact goes against the contention that La Niña may be driving more rainfall via atmospheric river intensification. I conveniently have not highlighted this fact until now. And that is because the rest of my viewpoint is correct 😜. Jokes aside, here I would default to the idea of scientific consensus. Consensus is achieved through scientific methods, which in their essence, are an attempt to seek the truth. The archaic definition of science is knowledge of any kind from the Latin root, scientia, meaning knowledge. Science today can be differentiated from general knowledge in that science is as systematic as possible. In that regard, some of the core tenets of the modern-day scientific method, like peer review and reproducibility, serve as checks and balances driving the process toward an ideal iterative truth. Science is not infallible as it is governed by individuals collectively. And it is possible for that collective to get things wrong, as we saw in Wegener’s proposal of the theory of plate tectonics. But science is not absolute in that you don’t prove. You disprove to refute and mount evidence to support. And in that sense, it is a constantly evolving, dare I say, a changing process.

My question now is, if the La Niña phase of ENSO continues, what will our Pacific Northwest summer have in store? The climate impact trends suggest that La Niña has minimal effect on the Pacific Northwest summer. La Niña’s effects are felt more in the winter. The next question is whether reduced temperature differentials will slow and buckle the polar jet stream? And if so, what kind of kinky weather will those bends bring beyond the borders of the polar vortex.

The images below are the forecasted climate drivers (ENSO and IOD) from the Australian Government’s BOM for the spring and summer. These drivers are trending towards La Niña and a negative IOD. The question then becomes are these correct and what will that mean weatherwise?


Government of Canada, Public Services and Procurement Canada. “Information Archivée Dans Le Web.” Publications.gc.ca, publications.gc.ca/collections/collection_2020/eccc/en84/En84-218-1998-eng.pdf.

‌“La Nina – 1988 – 1989.” Science on a Sphere, sos.noaa.gov/catalog/datasets/la-nina-1988-1989/.

“Scientific Models.” Www.education.vic.gov.au, www.education.vic.gov.au/school/teachers/teachingresources/discipline/science/continuum/Pages/scimodels.aspx#:~:text=A%20scientific%20model%20is%20a.

Trenberth, Kevin, and Timothy Hoar. Longest on Record. no. 1, 1996, www.cgd.ucar.edu/staff/trenbert/trenberth.papers/THoar1996GRL.pdf.

US Department of Commerce, National Oceanic and Atmospheric Administration. “What Is a Heat Dome?” Noaa.gov, 2019, oceanservice.noaa.gov/facts/heat-dome.html.

ENSO Climate Impacts by Phase and Season

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