It was a little more than 10 years ago that I published my first blog posts on the obvious upward steps in the sea surface temperatures of a large portion of the global oceans…upward steps that are caused by El Niño events…upward steps that lead to sunlight-fueled, naturally occurring global warming.
There is a very simple explanation for those El Niño-caused upward shifts that also make themselves known in the sea surface temperature data for much larger portion of the global oceans than I first presented a decade ago…the upward steps that are blatantly obvious in the satellite-era (starts November 1981) of sea surface temperature data for the South Atlantic, Indian and West Pacific Oceans, as shown in Figure 1, which together cover about 52% of the surfaces of the global oceans.
NOTE: The upward steps are not a peculiarity of the sea surface temperature dataset (NOAA’s Reynolds OI.v2) presented in Figure 1. They are also plainly visible in the graphs for the same region using the UKMO HADISST dataset (graph here) and using NOAA’s “Pause-Buster” ERSST.v5 dataset (graph here). Of course, Tom Karl’s “Pause Buster” sea surface temperature data show the most warming. [End note.]
The explanation for the upward steps for the most part has been overlooked…or the explanation might have been purposely ignored by the climate-science industry, because the financial foundation of their livelihoods is human-induced global warming not naturally occurring global warming. When you see how simple the explanation is for those naturally caused upward steps, you might conclude that the climate-science industry has, in fact, purposely ignored Mother Nature’s handiwork and willfully misled the public about the cause of global warming.
In the preceding paragraph, I wrote the explanation for the most part has been ignored. The only place I know that it wasn’t ignored is in my ebook Dad, Why Are You A Global Warming Denier?, which was first published about a year ago. Now, it’s being discussed once again in this post.
Note: For this discussion, we’re using one of the classic definitions of an El Niño event, where Eastern Equatorial sea surfaces temperatures in the tropical Pacific rise above a threshold due to coupled ocean-atmosphere processes (described later in this post) and stay elevated for more than a couple of months. In other words, this is not a discussion of a different type of El Niño, like El Niño Modoki. More specifically, I use a typical definition of an El Niño event, as reflected in the sea surface temperature anomalies of the NINO3.4 region of the eastern equatorial Pacific. That is, El Niño conditions are said to exist when NINO3.4 sea surface temperature anomalies meet or exceed +0.5 deg C.
The upward steps do not happen in response to all El Niño events. The upward steps shown in Figure 1 occurred in response to the 1986/87/88, the 1997/98, the 2009/10, and the 2014/15/16 El Nino events. They are most likely to occur during strong East Pacific El Nino events that are not opposed by volcanic eruptions. That is, the aerosols emitted by the 1982 eruption of El Chichon counteracted the aftereffects of the 1982/83 El Niño, which was comparable in strength to the 1997/98 “super” El Niño, and the aerosols emitted by the 1991 eruption of Mount Pinatubo overwhelmed any aftereffects from the 1991/92 El Niño.
For further insight to the El Niño events that caused the upward steps, I’ve included the discussion below. It is based on NOAA’s Reynolds OI.v2 sea surface temperature anomaly data for the NINO3.4 region (5S-5N, 170W-120W), with the data downloaded through the KNMI Climate Explorer and the anomalies referenced to the period of 1981-2010. Specifically:
- For the 1986/87/88 El Niño, NINO3.4 sea surface temperature anomalies reached or exceeded +0.5 C in September 1986, peaked at +1.7 deg C in September and October 1987, and remained above or equal to +0.5 deg C through January 1988.
- For the 1997/98 El Niño, NINO3.4 sea surface temperature anomalies reached or exceeded +0.5 C in May 1997, peaked at +2.7 deg C in November and December 1997, and remained above or equal to +0.5 deg C through May 1998.
- For the 2009/10 El Niño, NINO3.4 sea surface temperature anomalies reached or exceeded +0.5 C in June 2009, peaked at +1.7 deg C in December 2009 and remained above or equal to +0.5 deg C through April 2010.
- For the 2014/15/16 El Niño, NINO3.4 sea surface temperature anomalies reached or exceeded +0.5 C in October 2014, peaked at +3.0 deg C in November 2015 and remained above or equal to +0.5 deg C through April 2016.
All four El Niño events peaked at, at least, a NINO3.4 sea surface temperature anomaly of +1.7 deg C, and the NINO3.4 sea surface temperature anomalies remained at or above +0.5 Deg C for a minimum of 11 months.
A BRIEF OVERVIEW OF THE REASON FOR THE EL NIÑO-CAUSED UPWARD STEPS:
First, you have to consider that the tropical Pacific and the ocean gyres in the North and South Pacific are acting as a natural heating system, with the tropical Pacific acting as the boiler and parts of the Pacific gyres outside of the tropics acting as the heating coils and baseboard radiation. That is, in the tropics (the boiler), the ocean surface waters are warmed by the sun as they travel from the Americas in the east to Australia and Indonesia in the west. As those sunlight-warmed waters travel around the rest of the circuits of the North and South Pacific gyres (the heating coils and baseboard radiation), they release the heat gained in the tropics to the atmosphere, primarily through evaporation.
The aftereffects of strong East-Pacific El Niño events are comparable to sending a good amount of the water in a hot-water heating system back through the boiler a second time, with a bypass circuit, before the twice-boiler-heated water is sent out to the heating coils and baseboard radiation. That is, the water is sent back through the boiler another time before it has made its circuit of the rest of the heating system. What? you say. Yup, it’s that simple…so simple that even a child can understand it. Of course, a strong East Pacific El Niño event causes a long-term rise in global surface temperatures. There’s no way it could not.
I’ll provide a more-detailed explanation later in this post, along with an explanation of how La Niña events are NOT the opposite of El Niño events.
Note: For persons having trouble imagining this with a piped heating system, consider that the ocean gyres are not piped, but are open to the atmosphere. So imagine open tanks at the inlet and outlet of the boiler, with the bypass piping and pump from the discharge tank to the inlet tank, in addition to the pump for the boiler and the pump for the piping to the heat coils and baseboard radiation. [End note.]
WHAT PROMPTED THIS POST
Occasionally during his Daily Updates and Saturday Summaries at Weather Bell Analytics, which I watch daily, and while displaying a graph of global Lower Troposphere Temperature (TLT) anomalies (Figure 2), Joe Bastardi refers to the obvious El Niño-caused upward shift in the global lower troposphere temperature anomalies caused by the 1997/1998 “super” El Niño. He then suggests that another upward step may have been caused by the 2014/15/16 El Niño.
The source of the graph in Figure 2 is the Global Temperature Report from the Earth System Science Center at the University of Alabama in Huntsville, specifically the webpage here.
A MORE-DETAILED PREFACE
The El Niño-caused upward steps in sea surface temperatures were first illustrated and discussed way back in January 2009 in my two-part post Can El Niño Events Explain All of the Global Warming Since 1976 (Part 1 at WattsUpWithThat is here, with the cross post of Part 1 at my blog here, and Part 2 at WattsUpWithThat is here, with the cross post of Part 2 at my blog here.) Years later, I began to include El Niño-caused upward shifts for a much large portion of the global oceans in my monthly satellite-era sea surface temperature anomaly updates, which I haven’t updated for more than 2 years. The South Atlantic, Indian, and West Pacific represent about 52% of the surface of the global oceans.
Between my first two posts ten years ago and the publication of Dad, Why Are You A Global Warming Denier? a year ago, after years of research into El Niño and La Niña processes, after dozens of posts about them and after a multitude of same-topic conversations with the visitors to WattsUpWithThat and my blog Climate Observations, I published my free ebook Who Turned on the Heat? – The Unsuspected Global Warming Culprit, El Niño-Southern Oscillation. I can proudly say that Who Turned on the Heat? is the most-detailed introduction to, and discussion of, the coupled ocean-atmosphere processes that drive El Niño and La Niña events. It was specifically written for non-technical people, and, for documentation, it presents data that’s readily available to the public. Who Turned on the Heat? should answer any questions you might have now about El Niño and La Niña processes, excluding the discussion of sending the waters a second time through the boiler. For that you’ll need to refer to…
A LONGER INTRODUCTION TO THE EXPLANATION FOR THE EL NIÑO-CAUSED UPWARD STEPS
The following bold-faced text (in italics) comes from my ebook Dad, Why Are You a Global Warming Denier?. It is part of a conversation between a daughter (Anna) and her Dad, and it’s written in the first person by Anna. It provides a reasonably easy-to-understand, non-technical (as non-technical as I can get), explanation for the upward steps in the sea surface temperatures of the South Atlantic/Indian/West Pacific Oceans that are caused by strong East Pacific El Niño events.
In my ebook Dad, Why Are You A Global Warming Denier?, the following text is included under the heading of:
SATELLITE-ERA SEA SURFACE TEMPERATURE RECORDS STRONGLY SUGGEST THE SURFACES OF THE GLOBAL OCEANS WARMED NATURALLY SINCE THE EARLY 1980S
About 40% of the way into the short story, Anna writes, recalling a conversation with her Dad [Begin Reprint]:
He began, “Have you ever heard of El Niño and La Niña events, Anna?”
“Most news stories about El Niños call them unusual warming events in the eastern tropical Pacific Ocean, off the west coast of South America. They’re the cause of the huge upward spikes we see in the global surface temperature graphs.”
“They are much more than just warming events, and, further, regardless of what the numbskull science reporters say, there’s nothing unusual about them.” Dad shook his head disgustedly. “Magnificent would be a better word. Here are the facts. El Niño events occur every two to seven years. El Niños are the most-amazing, and the most powerful, weather events ever devised by Mother Nature. How powerful? El Niños are often kick-started by series of tropical storms in the western tropical Pacific.
“How’s about we start with an overview about how they cause long-term global warming and do it naturally. Ready?”
“Ever since I got home, Dad.”
“Okay, hold on for a few minutes while I get the globe from your bedroom.” Dad returned with a globe I’ve had sitting on a bookshelf since I was in grade school. He gave it an enthusiastic spin and sat beside me, before placing it on the table between us. He stopped the globe’s spinning and turned it so the Pacific Ocean faced us. From my viewpoint, the Pacific Ocean, with very little land, was all I could see. It was a great reminder of just how massive the Pacific Ocean was.
As if reading my mind, Dad said, “As you can see, Anna, the tropical Pacific Ocean stretches almost halfway around the globe.”
“From Indonesia in the west to South America in the east,” I confirmed, tracing my index finger along the equator. “The Pacific Ocean is humungous!”
“Indeed. Now, the surface waters in the eastern tropical Pacific are normally cooler than the waters in the western portion. And there’s a simple explanation. The eastern boundary currents along the coasts of North and South America return cool waters from the extratropics to the tropics.” He traced his index finger southward along the west coasts of North and Central Americas then traced it northward along the west coast of South America. “During normal conditions, the trade winds push those cool waters from the eastern tropical Pacific all the way halfway around the globe across the tropical Pacific, under the warm tropical sun, pushing it ever westward until all of that sun-warmed water runs into Indonesia and Australia.” While he said the last sentence, he pretended to push water from east to west all the way across the tropical Pacific, from the west coast of South America at Ecuador, to Indonesia and Australia.
He then traced his finger along the equator in the eastern tropical Pacific, as he said, “In the eastern equatorial Pacific, east of the dateline, the trade winds also cause cool water from deep below the surface to be drawn to the surface in a process called upwelling. That cool water is also warmed by the sun as it travels to the west, pushed by the trade winds, almost halfway around the globe in the tropical Pacific.”
“Okay, got that.”
“The western boundary currents carry those sunlight-warmed waters toward the poles where those poleward-traveling waters release the sunlight-created heat to the atmosphere.” As he spoke, he continued his demonstration, finger-tracing poleward in the South Pacific, east of Australia, then switching hemispheres and tracing the North Pacific east of Asia.
“Got that too, Dad. You’re describing ocean circulation.”
“Bingo. However, at the same time, a lot of the sunlight-warmed water accumulates in the western tropical Pacific in what’s called the Pacific Warm Pool.” With his finger, my father roughly circled an area east of Indonesia and north of Australia. “So, imagine a pool of water about the size of the United States, one thousand feet deep.”
“That’s a huge chunk of warm water.”
“Yup. Everything about the Pacific Ocean is huge.
“The massive currents that carry that sunlight-warmed water from east to west in the tropical Pacific are called the North and South Equatorial Currents.”
“Along the equator, there’s also a much smaller current that travels in the opposite direction, from west to east, called the Equatorial Countercurrent. And below it there’s another west-to-east current that runs below the surface called the Cromwell Current, also known as the Pacific Equatorial Undercurrent. Those eastward-moving surface and subsurface currents are normally carrying much less water than the westward-moving North and South Equatorial Currents.”
“I’ve got you so far, Dad. And you’ve said sunlight-warmed a bunch of times.”
“Just setting the stage and reinforcing that fact.”
His use of the word normal in his explanations prompted me to interject, “But something happens that causes changes in those normal conditions.”
“Bingo!” He smiled broadly. “A westerly wind burst, sometimes caused by a tropical storm—or two of them straddling the equator—upsets the balance and sends a huge pulse of warm water from west to east along the equator. Keep in mind that it’s normally warmer in the western tropical Pacific than it is in the eastern portion. That pulse of warm water moves along the surface, but most of it is carried below the surface along the Cromwell Current. If there are enough of those westerly wind bursts in the western tropical Pacific one year, and if enough warm water travels east at and below the surface to raise the normally cooler surface temperatures in the central and eastern equatorial Pacific by more than 0.5 deg C, then El Niño conditions are said to be taking place.”
“That’s pretty cool, Dad.”
“Nope, pretty warm, Dear.”
I groaned, with a smile.
“And if the surface temperatures stay elevated in the central and eastern equatorial Pacific for about half a year, then a full-fledged official El Niño event is said to have taken place.”
“Gotcha. El Niño conditions means the sea surface temperature anomalies in the eastern equatorial Pacific have risen above a 0.5 deg C threshold, and if they stay elevated for about half a year, then an official El Niño event is taking place.”
“And El Niño events typically peak during the boreal winter. The westerly wind bursts start much earlier in the year. It takes a couple of months for the warm water from the West Pacific Warm Pool to travel eastward toward South America. Now keep in mind that it takes multiple westerly wind bursts to send enough warm water eastward to cause an El Niño. So the birth of an El Niño by Mother Nature takes about a half a year, sometimes longer, sometimes shorter. Oh yeah, El Niños typically start in one year and end in the next. Thus you’ll see them expressed, for example, as the 1997/98 El Niño.”
“It must be fascinating to watch El Niños form.”
“NOAA and Australia’s Bureau of Meteorology (BOM) monitor lots of atmospheric and oceanic variables in the tropical and equatorial Pacific, so you can actually watch the slow birth of an El Niño online as it occurs over many months.
“Now, let me clarify something. In an El Niño, a monstrous volume of warm water traveled from the West Pacific Warm Pool to the eastern side of the tropical Pacific, where it’s normally cooler. No new warm water was created. It was just relocated from the Western Pacific Warm Pool, where it’s normally warmer, to the eastern equatorial Pacific, where it’s normally cooler. And the warm water that had been below the surface, traveling from west to east along the subsurface Cromwell Current, it gets upwelled to the surface in the east.”
“Okay, I understand.”
“And during very strong El Niño events, so much warm water is carried east that most of the warm water, above and below the surface, is now in the eastern tropical Pacific instead of where it normally is in the western tropical Pacific. That is, the surface and subsurface conditions—normally warmer water in the west and cooler in the east—have traded places.”
“That’s a lot more detailed and helpful than the simple explanation we hear on the news. Then, because the news media call it an unusual warming event, people like me who don’t understand the process get mixed up and think the El Niño is caused by global warming.”
“When just the opposite is the case. An El Niño can cause a naturally occurring, sunlight-fueled, long-term global warming.”
“So that is the natural causation you were talking about,” I said nodding enthusiastically, “El Niño!”
“Right you are. But before I get into that in more detail, I need to clarify something. Because of the process called upwelling, during the El Niño, there is more warm water than normal spread across the entire tropical Pacific, sometimes as far east as the coast of South America. With all of that warmer-than-normal water spread across the eastern tropical Pacific, much more evaporation is taking place there. So the tropical Pacific is releasing monumental amounts of sunlight-created heat to the atmosphere.” My father paused, gave me an attention-grabbing look, and said, “But, not all of the warm water that has traveled east is cooled all the way back to normal by evaporation. So, and this is very important, the renewed trade winds push all of that leftover warm all the way back across the tropical Pacific, being warmed a second time under the tropical sun—let me repeat that, being warmed a second time under the tropical sun—before being sent poleward by the western boundary currents.”
“In a hot water heating system,” I said, thinking of my current and Dad’s former work, “that would be like recirculating warm water a second time through the boiler, heating it more, before pumping it out to the heating coils and baseboard radiation.”
“Yes!” Dad chuckled. “That’s precisely what I thought when I first realized this.”
After that 1.700-word introduction, the explanations for the upward steps continue for another 3,000 words in Dad, Why Are You A Global Warming Denier?, then move onto a discussion and explanation of the naturally occurring Atlantic Multidecadal Oscillation, which caused the sea surfaces of the North Atlantic in recent decades to warm at a higher rate than the naturally caused warming by strong El Niño events of the South Atlantic, Indian and West Pacific Oceans.
Also discussed is how La Niña events replenish the warm water in the West Pacific Warm Pool. The sea surface temperatures in the Eastern Equatorial Pacific are cooler than normal during a La Niña, and because they’re cooler, there is less evaporation taking place, and further, with less evaporation, there is less cloud cover, so sunlight is able to reach into the tropical Pacific and warm it to depth.
HOW A LA NIÑA IS NOT THE OPPOSITE OF AN EL NIÑO
As a reminder: During normal times the trade-wind driven North and South Equatorial Currents in the tropical Pacific carry waters almost halfway around the globe, and that water warms as it goes halfway around the world under the tropical sun. After that one pass along the tropical Pacific, some of that sunlight-warmed water is stored in a large, deep pool called the West Pacific Warm Pool, without having made a complete circuit of the North or South Pacific gyres where they can more readily release heat to the atmosphere at mid-to-higher latitudes, primarily through evaporation. The volume of warm water in the West Pacific Warm pool increases with time and is often dramatically increased during La Niña events, when a reduction in cloud cover allows sunlight to reach into the tropical Pacific and warm it to depth.
With a strong East Pacific El Niño, a huge volume of warm water from the West Pacific Warm Pool is driven eastward to the Eastern Tropical Pacific, as far as the coast of South America, where the surfaces are normally cooler than in the West Pacific Warm Pool. At the end of the El Niño, when the trade winds resume their normal east-to-west operation, all of the warmer-than-normal water in the eastern tropical Pacific—that’s left over from the El Niño—is driven west to be warmed a second time under the tropical sun as it travels halfway around the globe before it then is driven toward the poles so that it can release heat to the atmosphere, primarily through evaporation. Phrased another way, after the El Niño, the surface waters are warmer than normal in the Eastern Tropical Pacific before they begin their trip across the tropical Pacific under the warm tropical sun. There’s no way that a strong East Pacific El Niño cannot contribute to long-term global warming.
Does the opposite happen during a La Niña? Here’s the real clincher. At the end of the La Nina, when the trade winds weaken to their normal east-to-west strengths, is all of the cooler-than-normal water in the eastern tropical Pacific—that’s left over from the La Niña—driven west to be cooled a second time under the tropical sun as it travels halfway around the globe before it then is driven toward the poles so that it can absorb heat from the atmosphere? Of course not. Anyone who says a La Niña is the opposite of an El Niño is announcing their ignorance of El Niño and La Niña processes for the world to see—or—they are willfully misrepresenting those processes.
THE CHARGE [RECHARGE] OF OCEAN HEAT CONTENT IN THE TROPICAL PACIFIC BEFORE [AFTER] AN EL NIÑO
A tremendous amount of heat is released from the Tropical Pacific during an El Niño. Where does the ocean heat come from and how is it recharged? Part of that heat loss, or all of it (plus some more on occasion) can be created immediately before the El Niño (as was the case before the 1997/98 Super El Niño during the thought-to-be-weak 1995/96 La Niña) or restored afterwards by the coupled-ocean atmosphere processes that take place in the tropical Pacific during La Niña events, as happened during the 1998/99/00/01 La Niña. (You can confirm the timing and length of those La Niña events with the Oceanic Niño Index here.) Colder-than-normal sea surface temperatures in the tropical Pacific during a La Niña lead to less evaporation than normal there, which results in less cloud cover than normal there, which allows more sunlight (downward shortwave radiation) than normal to enter into the Tropical Pacific thus charging (recharging) the ocean heat.
Thus, El Niño and La Niña events act together as a chaotic, naturally occurring, sunlight-fueled, recharge-discharge oscillator, with El Niño events acting as the discharge phase and La Niña events acting as the recharge phase. Simple.
And before someone makes some bizarre claim about longwave (infrared) radiation being responsible for the charge/recharge during La Niñas, there’s a problem with that logic. Why? you ask. Because downward longwave radiation increases over the Tropical Pacific during the El Niño phase, when the tropical Pacific is releasing heat, and downward longwave radiation decreases over the Tropical Pacific during the La Niña phase, when the tropical Pacific is charging heat.
The recharge aspect of La Niña events was discussed and documented with data in lots more detail in Chapter 3.10 The Recharge of Ocean Heat during the La Niña of my free ebook Who Turned on the Heat? – The Unsuspected Global Warming Culprit, El Niño-Southern Oscillation.
AND FOR THOSE WHO WANT TO SAY THAT GLOBAL WARMING IS CAUSING EL NIÑO EVENTS TO BECOME STRONGER
The sea surface temperature anomalies of the NINO3.4 region (5S-5N, 170W-120W) of the equatorial Pacific are a commonly used metric for the timing, strength and duration of El Niño and La Niña events. During the satellite era, the trend of the sea surface temperature anomalies for the NINO3.4 region is a flat line, with a trend of -0.004 deg C/decade. See Figure 3.
Note: It’s ENSO indices like NINO3.4 sea surface temperature anomalies, Figure 3, that give some people the mistaken belief that La Niña events are the opposite of El Niño events, but ENSO indices do not represent the processes of El Niño and La Niña events. Those indices only reflect the effects of the El Niño and La Niña events on the metric being observed. [End note.]
You may have a question like, Why didn’t the longest-and-strongest 2014/15/16 El Niño create more of an upward step in the sea surface temperatures of the South Atlantic, Indian and West Pacific (Figure 1)? We’ll investigate that and present the findings in an upcoming post. And I don’t believe you’ll be surprised.
That’s it for this post.
Have fun in the comments and enjoy the rest of your day.
STANDARD CLOSING REQUEST
Please purchase my recently published ebooks. As many of you know, this year I published 2 ebooks that are available through Amazon in Kindle format:
- Dad, Why Are You A Global Warming Denier? (For an overview, the blog post that introduced it is here.)
- Dad, Is Climate Getting Worse in the United States? (See the blog post here for an overview.)
And please purchase Anthony Watts’s et al. Climate Change: The Facts – 2017.
To those of you who have purchased them, thank you. To those of you who will purchase them, thank you, too.