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Climate Hustle

NASA scientists expect more rapid global warming in the very near future (part 1)

Posted on 26 January 2012 by Rob Painting

As a recent SkS post by Dana Nuccitelli has pointed out global warming hasn't stopped, despite a recent lull in global surface temperatures. The oceans, which are the main heat sink for global warming, have scarcely skipped a beat in soaking up heat. The hiatus in global surface temperatures appears to simply be a reflection of natural variability, principally the exchange of heat between the ocean surface and the atmosphere. But we shouldn't expect this to last much longer. Eventually that ocean heat buried in deeper layers will come back to the surface, and we'll experience the warm phase of this natural cool/warm (La Niña/El Niño-based) cycle.

As if to reinforce this very point, a group of scientists at the NASA Goddard Institute for Space Studies (NASA GISS), have released an analysis of global temperatures in 2011, and near-future prospects. They find that 2011 was the 9th-hottest year on record (9 out of the 10 hottest years on record since 1880, have occurred in the 21st century), and that this cool-ish year (by 21st century standards, but hot by 20th century standards) was largely due to the cooling influence of a quiet phase of the 11 year-long solar cycle (small changes in the intensity of sunlight reaching Earth), and La Niña which has been dominant over the last 3 years (See figure 1). They conclude that the lull is an illusion, and that rapid warming of global surface temperatures is likely to resume in the next few years.

Figure 1 - Global monthly and 12-month running mean (average) surface temperature anomalies relative to the 1951-1980 base period (GISTEMP), and the 12-month running mean of the Nino 3.4 index of sea surface temperatures (an index of La Niña/El Niño intensity and duration). Image adapted from NASA GISS.

Global warming is ocean warming

Covering around 70% of the Earth's surface, and having a heat capacity a thousand times that of the atmosphere, the oceans are the main reservoir of heat on the planet; indeed, over 90% of global warming actually goes into the oceans.

Carbon dioxide has a bit of a double-whammy effect on global temperature because not only does it trap more heat in the atmosphere, but it also traps more heat in the ocean. Because of this, and although not the only influence on climate, carbon dioxide is the Earth's main climate control knob

Greenhouse gases such as carbon dioxide dictate the amount of heat retained by the ocean over long intervals because of the manner in which they alter the temperature gradient in the 'cool skin' layer which is the oceans interface with the atmosphere. Increase greenhouse gases, and in the absence of counter-acting forces, ocean and global temperature rises too. 

This greenhouse gas control of ocean heating is why global temperatures exhibit a tightly coupled relationship with carbon dioxide over time. And is why carbon dioxide concentrations closely matches global temperature as revealed in the ice core records (Figure 2).  

Figure 2 - Vostok ice core records for carbon dioxide concentration (Petit 2000) and temperature change (Barnola 2003).

The warm/cool ocean cycle of El Niño/La Niña

The oceans affect global temperature through the heat that they exchange with the atmosphere, but this exchange is not a steady, or monotonic process. There are large annual and multi-year up-and-down fluctuations due primarily to the vast amount of heat which sloshes around in the equally vast Pacific Ocean. This phenomenon is the El Niño Southern Oscillation (ENSO), which is essentially the re-distribution of heat already within the climate system.

The large surface temperature fluctuations are due to the tilting of the thermocline, a term describing the wind-driven pooling of heat in surface and deeper layers of the western Pacific Ocean (near Papua New Guinea and the Philippines) during La Niña, and the leveling that takes place as the warm water wells back up, and spreads out over the central and eastern Pacific Ocean surface during El Niño. See this great animation to gain a clearer understanding of the process.

The upshot of these fluctuations is that the cool water which upwells to the surface along the Pacific coast of America, during La Niña, and the burial of warm water into deeper layers in the western Pacific, serve to cool global surface temperatures because of the surface heat exchange of cooler water with the atmosphere. It might seem counter-intuitive, but in spite of this the oceans are actually gaining substantial amounts of heat. It is the opposing warm phase, El Niño, when warm water rises up to the surface and warms the atmosphere that heat is lost from the ocean and it undergoes temporary cooling. See Roemmich & Gilson (2011).

A demonstration of the global scale of this overall heat burial/heat surfacing mechanism is apparent in figure 1, once major volcanic eruptions are accounted for. However figure 3, based upon data from the ARGO float network, provides a clear illustration of the heat being sequestered in the subsurface layers of the ocean during La Niña.

Figure 3 - (a) Time‐series of globally‐averaged (60°South to 60°North) temperature anomaly from the monthly mean, versus pressure (dbar). The contour interval is 0.02°C and values are smoothed by 3‐month running mean. (b) Time‐series of globally‐averaged sea surface temperature (black, °C), T160 - heat down to 160 metres (blue), and the Nino 3.4 index estimate for SST (red). Adapted from Roemmich & Gilson (2011).

And yes, the oceans are still warming

Because these annual and multi-year up-and-down temperature fluctuations can be as much as ten times as large (+/- 0.2°C) as the signal from the small (by comparison) annual increase in global warming, a period dominated by La Niña can temporarily obscure the warming trend in the global surface temperature record (see figure 1). This happens even though the oceans are steadily accumulating heat. See figure 4.

Figure 4 - Revised estimate of global ocean heat content (10-1500 metres deep) for 2005-2010 derived from Argo measurements. The 6-yr trend accounts for 0.55±0.10Wm−2. Error bars and trend uncertainties exclude errors induced by remaining systematic errors in the global observing system. See Von Schuckmann & Le Traon (2011).

Global temperature in 2011, trends, and prospects

With some background of the 'bigger picture' having now been spelled out, the analysis by NASA scientists James Hansen, Reto Ruedy, Makiko Sato and Kwok-Wai Ken Lo should, hopefully, be that much clearer.

As stated earlier, their analysis found 2011 as the 9th-hottest year in the NASA GISTEMP temperature record. All the ten warmest years have taken place in the 21st century, with the exception of 1998 - which was warmed by the largest El Niño of the 20th century.

By plotting the GISTEMP temperature series against a 12-month, 60-month (5 year) and 132-month (11 year) running means ( 12, 60 & 132-month averages) the authors show that the global warming signal becomes increasingly more apparent. The 60-month running mean removes much of the noisy influence of the multi-year El Niño/La Niña cycle, and the 132-month running mean removes both the El Niño/La Niña cycle, and the 11-year solar cycle (figure 5).

Figure 5 - Global surface air temperature anomalies relative to a 1951-1980 base period for a) the 12-month running mean, and b) the 60-month and 132-month running means.

The authors write:

"The current status of these running means (Fig. 5) adds some weak evidence for the frequent assertion that the rate of global warming has been less in the 21st century than in the last two decades of the 20th century. However, that impression is dependent on the end point, which is heavily influenced by the strong La Niñas in the past three years. If an El Niño occurs in the next few years, which is likely as we discuss below, the mean warming rate will probably exhibit no slowdown on the decadal time scale."

This is exactly the point made in the SkS post: Going down the up escalator - the illusion of no long-term warming is only accomplished by narrowly focusing on short term periods, and totally ignoring the long-term warming trend (figure 6).



Although the NASA scientists merely point this out for illustrative purposes, a more rigorous approach to remove the short-term natural fluctuations in order to reveal the underlying global warming trend was made by Foster & Rahmstorf (2011). They found that global warming continues its upward climb (figure 7).

Figure 7 - Annual averages of the adjusted global surface temperature data, - i.e. the global warming signal with short-term natural variability removed.

Next in Part 2: seasonal anomalies, the Arctic Oscillation, the solar cycle and other climate forcings.

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Comments 1 to 32:

  1. I've long been telling climate "skeptics" that the "lull" in warming isn't an indicator of coming cooling, it's an indicator of a coming phase of rapid warming. To quote Stephen Schneider in the video posted on SkS a few weeks ago, "You can't add 4W/m-2 to the planet and expect that it's not going to get warmer." That's just physics.

    I'm expecting a whopper of an El Nino sometime in the next few years.
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  2. The title does a disservice to the science. At the time of the Keenlyside modelling news (predicting at extended lull in AGW), statements were issued by sane scientists that there's nothing in AGW that precludes even a decade of pause - other influences have very strong short and medium signals.

    But ever since Lintzen gave his notorious interview to the NY Times in 2004, claiming that global warming stopped in 1998, there has been this absurd 'stare at the tea-kettle' pattern. Maunder-minimums, solar lulls, cosmic rays, and 'you-just-wait' from all sides ... it just don't work that away! The key certainties are the properties of the pollution, the energy imbalance, and the pH alteration.

    If the current drivers get locked in, double-dip La Nina's could pour deep-stored cool back into the atmosphere for decades. It's a zero-sum game so eventually it loses force. The only guess from the palaeoclimate record is that it could be a major force for up to 800 years (the deep-current cycle). Don't hand the pro-pollutionists short-term ice-cubes to keep delaying a response.

    Waiting for 'our new numbers' to fight 'their old numbers' is a fuels paradise. What counts is the observations - growing widespread extreme events and disruptions. We've been in the paradigm for decades, and the real issue is where it hits next ... and next ... and next ...
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  3. owl905 - "The title does a disservice to the science"

    Maybe you just can't read? Here's how the NASA scientists end their analysis:



    Dude, no one is handing fake-skeptics anything. It's very likely to get warmer over the next few years - that's what actual experts on the topic have found.

    I don't see that this is that difficult to grasp, the solar cycle is on it's upward (warmer) phase, and La Nina is eventually going to be replaced by the warm phase El Nino. Well, warm phase as far as humans are concerned - as the blog post makes clear the oceans cool as heat is lost to the atmosphere during El Nino.

    Now if you think this isn't going to happen I'd like to hear your reasoning, and citations supporting this. Otherwise you're just waving your arms.
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  4. The figures for arctic warming are even more scary.

    Arctic Temperatures Continue Rapid Rise as 2011 Breaks Record Set in 2010

    [John, new layout? Your html guidelines need updating from 450px to 570px width!]
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    [DB] Resized image width down to 500 pixels due to page layout breaking.

  5. andylee... If you look at the top of the page, 570px still breaks the formatting of the page.
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  6. I think owl905 raises a good point. I personally expect an El Nino, this year or next (this year would be much, much better from a US policy point of view).

    But warming doesn't end natural variation - we could get a triple dip La Nina. A weak El Nino. Stay ENSO neutral for 5 years. These outcomes are less likely.

    But given that the skeptics are trying to make a science issue political, it doesn't make any sense to give them any ammunition whatsoever. Let the observations speak for themselves. If warming is showing up at the decadal level for 30 years or more - than one can certainly claim the warming signal is so strong it even shows up at at the decadal level.

    But now or later, should the warming not show up for a given decade (solar influence, super La Nina, high volcanism, major aerosols (as a few vectors a 10 year flat or ever-so-slightly cooler could appear)) - those who ignore the science in favor of the political will again give shrill voice to the skeptic argument.

    While I respect this came from climate scientists at NASA I share Owl905's vague sense of unease that this could become fodder for the anti-science political propagandists.

    (Note the linked web page from NASA in the OP sheds light on all of the above and suggests the notably warmer part of the cycle is more likely in 2013 or 2014).

    I think on balance, I like the prediction. Because it is short term, very likely to be true, and if it isn't you could go right back to that page and look at the events the authors claim will cause the warming and observe they didn't happen.

    Let the skeptics show their colors by either understanding the nuance, or not.
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  7. @actually thoughtful, these explicit graphs should finally expose cognitively-challenged climate skeptics' attempts to subvert the obvious and embarrass them off the field.

    They are behaving just like turkeys trying to convince everyone else to vote for Thanksgiving Day.
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  8. Andylee, based on the evidence I predict the following:

    1. Deny it happening until that is 100% untenable. (We are about 50% through this - I still see "skeptics" in their native habitat darkly riding down the up escalator).

    2. Ratchet up the "there is no direct evidence that CO2 is to blame" - ie natural causes, the sun, cosmic rays, warming out of the ice age, climate has been changing for billions of years. This will be played until the end, whatever the end is. The next El Nino spike will be the last realistic chance of changing major government policy and being effective for this century (with relatively minor changes spread over decades).

    3. "There is nothing we can do about it" - ironically, the longer the skeptics are allowed to free range roam without the people rising up and demanding the established science be acknowledged and acted upon - the more true this one is. I personally take it as self-evident that this is the goal of the whole operation, insofar as rational thought is involved in anyway.
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  9. Actually Thoughtful - "But given that the skeptics are trying to make a science issue political, it doesn't make any sense to give them any ammunition whatsoever."

    Once again, this is not ammunition for fake-skeptics, it is an analysis of the scientific evidence. My challenge to him applies to you as well - if you think there's something wrong with the NASA analysis let's see what it is. The contribution of La Nina, and the cool phase of the solar cycle, to global temperature is rather large compared to Earth's radiation imbalance (i.e global warming).

    "Let the observations speak for themselves."

    The woman and man in the street isn't going to be able to make sense of the observations, especially with distortions by fake-skeptics. That's why we exist - to communicate this information in a, hopefully, comprehensible manner. To expect a public audience to be able to process this information without guidance is foolish.

    "Let the skeptics show their colors by either understanding the nuance, or not"

    No nuance necessary, both posts clearly spell out that the La Nina/El Nino phenomenon is cyclic, ergo it will not contribute to any long-term trend. Neither will the 11-year solar cycle - as pointed out in part 2. The small (in relative terms) but persistent, increase in greenhouse gases is causing global warming. The conclusion in part 2 makes this very explicit.
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  10. Re andylee "I fear it will be too late to mitigate without drastic action and a crash in the quality of life for the majority."

    I suggest we A) demand mandatory actions from the fossil companies (which rake in record profits and record subsidies) to fast pace transitioning to clean technologies OR B) to size their assets and do it.

    The question is: "How long do we wait?"
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  11. @Rob Painting - after citing examples of things that didn't come true, like the Kennlyside model forecast, you want examples. Take your advice about reading and say to the man in the mirror.

    In 2009, the Maunder crowd feasted on NASA's downward Solar Cycle 24 prediction to a peak of 90 - the lowest in a century.

    In 2010, the prediction peak dropped to 70:-

    In December 2011, the count hit 98 (and its still a year or two from the curve peak:

    As to the 'what I think', it's in the original post. Your response is a strawman, inferring that my opinion is a forecast of no imminent warming.
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  12. owl905 - in comment @ 2 you wrote that the title of this article was a disservice to the science, a blatant form of trolling. I pointed out to you that you were wrong, the NASA scientists are very clear on this point. Would it really have hurt for you to read the post or the NASA analysis before posting ill-informed comments? The rest of comment @ 2 has nothing whatsoever to do with the NASA analysis.

    Now you drag up Keenleyside, and previous predictions of the solar cycle - again nothing to do with the NASA analysis. It appears you are staunchly resistant to actually reading the NASA paper, so I'll make this clear:

    1. The solar cycle has already started it's ascent to the peak of the next cycle. It will take around 18 months for this extra heat to manifest itself in global surface temperatures because of the thermal inertia of the oceans. If you think this won't happen please explain how such a thing is possible.

    2. As explained in this post El Nino and La Nina are the flip sides of a natural oscillation. They balance out to zero over the long-term. We are overdue a few El Nino, and therefore more rapid warming of surface temperatures. If you think this won't happen in the next 2-3 years it would be interesting to hear how this is possible.

    3. Both these natural cycles are large compared to the planetary energy imbalance. So they can have a significant impact if they either oppose or reinforce the global warming signal. If you don't think this is so please enlighten us.

    4. And lastly, what you think passes for learned comment is not so here. An anonymous person on the internet is not more qualified than eminent scientists from NASA. Hopefully you have sufficient humility to realize that.
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  13. How much of the heat that is stored in the deep ocean not coming back in decade timescales? I.e. if some deep water is warmed from 35F to 35.1F it will not warm the atmosphere if it rises back to the surface.
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  14. The winter thus far in the Northeast (US) Has been 'wimpy'. Also of note the USDA has come up with its new map of climate growing zones- reflecting a warming climate. Gardeners will delight in knowing their gardens have been kicked up a half zone or more. Fig trees in Boston? Yes. Palms along the southern New England coast? Yes.

    The USDA Map reflects the years 1976-2005- with digital imaging.
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  15. Eric @14

    As a lukewarmer, I must admit that there seems to be some confusion of surface temperature warming with heat energy absorption in the oceans in this post.

    If ENSO is an internal redistribution of global heat then warmer water and air somewhere must be balanced by cooler water or air somewhere else.

    The net accumulation of heat in the oceans is listed above as 0.5+/0.1Wm-2 for 6 years down to 1500m depth whereas research quoted by Ari on 24Jan SKS post has this statement from Loeb et al:


    The difference is in the confidence limits which are much larger in the Loeb paper.

    With this global heat accumulation stored as slightly elevated temperatures in the oceans - then the complex circulations can only move heat deeper if it is given up to cooler water.

    I would like understand the mechanism of how this heat gets back up into the atmosphere.
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  16. victull,

    ENSO is a result of a coupling of atmospheric and oceanic dynamics. During the La Nina years, the easterly trade winds over equatorial Pacific is abnormally strong. The result is that the warm surface water piles up along the western boundary.

    As ENSO transitions from a La Nina to an El Nino state, the trade wind weakens, and the water water spreads out over the surface due to gravity (warm water on the west is less dense compared to the cooler warm to the east). The result is the warm abnormality that you see during El Nino years. When the surface is warmer than usual, either heat is released into the atmosphere, or the ocean is absorbing heat at a lower rate. Both of these results in elevated atmospheric temperatures over the surface.

    Below is a series of graphics depicting the transition (from NASA earth observatory)

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  17. victull - "I would like understand the mechanism of how this heat gets back up into the atmosphere."

    Even a tiny change in sea surface temperature affects heat flow in/out of the atmosphere. What the ENSO does is allow (in La Nina) more energy from the TOA imbalance to go into the oceans by warming cool surfaces, or alternatively slightly reduce the energy flow into the oceans due to warmer surface waters (lower gradient, hence lower flow into the oceans) meaning that imbalance goes into the atmosphere instead.

    The oceans represent ~93.4% of the heat storage, the atmosphere ~2.3% - a very small change for ocean heat flow is by comparison a very large change for atmospheric heat flow.


    See also the Deep Ocean Warms When Global Surface Temperatures Stall thread.
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  18. Eric (skeptic)- "How much of the heat that is stored in the deep ocean not coming back in decade timescales?"

    Probably none. See SkS post on Meehl (2011) - Ocean Heat Poised To Come Back And Haunt Us? It's heat in the surface layers of the ocean that are lost to the atmosphere. That's why the oceans lose heat during El Nino - nothing to do with the deep ocean.

    Victull @ 15 - The confusion is yours, no point in trying to blame the blog post . In one sentence you point out that heat lost during ENSO must be balance by cooling elsewhere, and the very next you write about the warming rate highlighted in Loeb (2012). You gave yourself a very strong clue toward processing this information, but then failed to connect the two.

    Sunlight entering the surface layers warms the ocean. La Nina is when there is a large gain in ocean heat, and El Nino is when the heat is lost to the atmosphere. Although the cloud-related changes due to ENSO do affect sunlight reaching the ocean surface, the tilting of the thermocline is essentially a re-distribution of this heat already in the ocean. It's that process which affects surface temperatures so greatly. This information is spelled out in the post.
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  19. Re times for deep ocean heat to make a difference see Winton, Takahashi, and Held, 2009:  Importance of ocean heat uptake efficacy to transient climate change. J.Clim, 2009

    Deep ocean is 98% of the water so there is a 50-fold dilution of whatever excess CO2 and heat is sunk into it by the overturning circulation. Takes about 1000 years to make it back up.
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  20. Continuing....
    Most of the excess CO2 and heat is still in the surface layer. The North Atlantic is the only place with a lot of excess CO2 (and presumably heat) below the thermocline (Sabine et al 2002) and thus kept away from the atmosphere for a thousand years. That is the only part that can be considered to be in long-term storage.

    So yes, most of the excess CO2 and heat is now in the ocean. But it is only in the wind-stirred surface layer and not really in long-term storage.
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  21. Victull, you say:


    And you also say:


    If you don't understand this mechanism, which is not an unimportant one by any means, why would you describe yourself as a "lukewarmer"? Shouldn't you hold off on applying that sort of label to yourself until you've understood the mechanisms under discussion?

    I don't mean this an attack. I'm honestly curious. What is the justification for presuming to know the most likely outcome of a process that you concede you don't adequately understand?
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  22. A small typo. The word "monotonous" just after Fig 1 should presumably be "monotonic."
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    Moderator Response: [Rob P] Fixed thanks. Mind you it would be tedious and boring!
  23. I wrote this one before, it appears to have gone missing.

    Rob Painting - your reply to me relies on part 2, which as of this writing, is not available. The concerns raised by some posters here indicate that part 1 may not be able to stand on its own.

    While you are welcome to your opinion - I find this statement incredibly elitist: "The woman and man in the street isn't going to be able to make sense of the observations, especially with distortions by fake-skeptics. That's why we exist - to communicate this information in a, hopefully, comprehensible manner. To expect a public audience to be able to process this information without guidance is foolish."

    At the end of your reply to me you mention there is no nuance. If you don't understand why people are confused by short term weather patterns, that could be a root cause of why this post is getting so many responses of the "there be dragons" type.
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  24. Actually Thoughtful - here's the thing, on the one hand you suggest people work things out for themselves, and on the other you say (as if speaking on behalf of most) that things are not clear. Do you see the rather large contradiction here?

    In fact your initial suggestion of letting people works things out for themselves actually invites people to fill in the gaps in their knowledge with "there be dragons" and other modern-day variants thereof - you know climate myths.

    We know for instance that many members of the public cannot wrap their heads around the fact that the scale and rate of climate change now happening far exceeds that of major extinction events in Earth's history. People hear that climate has changed in the past and fall for this simple-minded propaganda. This distortion of the truth has to be continually corrected. There is no point in relying upon the man or woman in the street to work things out for themselves - they get the bulk of their misinformation and myths from the mainstream media.

    "I find this statement incredibly elitist:"

    Who cares? That's a subjective interpretation you have chosen to apply. Are you now suggesting that the general public is well-acquainted with climate science? Many a poll suggests that that isn't the case.

    " If you don't understand why people are confused by short term weather patterns"

    Many people are confused on a great many things, especially when it comes to climate science. But I don't confuse an attempt at trolling (casting doubt in this case) by several individuals as indicative of what people might think in general, and there is certainly no way to correct confusion in one blog post.

    Now it's just me, but I think it might be useful for the general public to understand the reasons why we are likely to get rapid global warming over the next 2-4 years (or thereabouts). Maybe when it happens a light bulb will go off in their heads and they'll remember "Hang on, there was some NASA scientists that said this was going to happen, and it's because of the solar cycle and El Nino!" That would be preferable to the alternative of filling knowledge gaps with myths.
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  25. At the street level many people are unaware or only vaguely aware that there is such a thing as climate data.
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  26. Rob,

    Thanks for a great post. Very lucid. Scientists in the past have been reticent (at least publicly) in linking global warming with El Nino / La Nina. Now for the first time it is crystal clear to me how these phenomena interact. Hopefully analyses such as this will help disarm the myth about global warming slowing or stopping.
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  27. phila@21, rob painting@18, kr@17

    kr@17, you seem to suggest that ENSO is a cyclical external forcing which opens and closes a heat absorption window on the TOA imbalance. ie a cycle driving a rising trend line.

    Did ENSO exist prior to the industrial release of CO2 and other GHG when there was no TOA imbalance due to GHG?

    I looked at your link to SKS post "Deep ocean warms etc ..and ran aground on the long posts by David Lewis which opened up the Hansen - Trenberth differences on warming magnitude.

    Rob@18 You have explained @9 and in the post that ENSO as a cyclical phenomenon which does not contribute to a long term trend. This is difficult to reconcile with you post title "NASA scientists expect more rapid global warming in the very near future" as the La Nina comes to an end.

    It is not global warming if heat already sequestered in the oceans is given up to the atmosphere in an internal ENSO cycle. It is heat transfer from one part of the system to another. El Nino air temperatures may rise a lot more than sea temperatures cool, but the reverse occurs when La Nina returns.


    I don't have a problem understanding heat exchange between the surface waters (down to 500-700m) and the atmosphere but when heat is given up to much deeper cool waters - the return path is much less clear to me.

    This has nothing to do with accepting that the oceans are absorbing a trend increase of about 0.5Wm-2. That means that the TOA imbalance exists and so does global warming.

    It seems that the 0.5 is much closer to the Hansen number which he suggests is due to models overestimation of ocean heat absorption and more aerosols - lukewarm - not so hot as Trenberth.
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  28. victull@15,
    The ENSO cycle is temporal variation in energy distribution, not a spatial one. Warmer water and air at the SURFACE is balanced by cooler water and air at the SURFACE some-when else.

    @27 ENSO has been around for a very long time, certainly throughout the industrial era. Since it existed early in the industrial era when the impact of GHGs on the atmosphere was very small, there is no reason to believe it did not exist before industrial emissions.

    Complaining about Rob@18's two statements: Sure, ENSO does not make a net contribution to long term anthropogenic greenhouse gas-induced warming, and technically, the "globe" actually cools during an El Nino. However, when an El Nino comes along, it makes the global surface temperature rise sharply. Surface temperature is the usual benchmark for "global warming", so colloquially speaking, the El Nino will "increase global warming". Obviously you understand the distinction between CO2-driven global warming and El Nino-driven surface warming, but if you try to get technical with the average reader and force them to understand that distinction, you'll probably just confuse them. (No offense.)
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  29. Victull @27 - Joe the Scientist has gone over this but......

    Yes, ENSO (La Nina/El Nino) is a cool/warm natural cycle. It is mainly a re-distribution of heat already within the system,.i.e the ocean either storing the heat below the surface layers (La Nina), or the heat rising up to the surface and spreading out across the eastern and central equatorial Pacific Ocean (El Nino). See the animation linked to in the post.

    When all that cool water is at the surface during La Nina, it exchanges heat with the atmosphere, but being cooler water, it leads to a temporary drop in global temperature. But now that cool water is at the surface, it gets heated by sunlight. Deep water that was once cool now warms up so the ocean gains a considerable amount of energy. In effect we have heat still stored in the subsurface layers in the western tropical Pacific, and the cool upwelled water along the west coast of the American continent being warmed by the sun. In addition, the cooler ocean surface leads to less evaporation which leads to less cloud cover which means more sunlight is able to reach the ocean surface. Understandably the oceans are going to soak up a lot of heat.

    During El Nino, of course, a fair chunk of that heat stored in the ocean is given up to the atmosphere (see figure 3), global temperatures rise rapidly and a lot of that heat is lost out to space.

    This cyclic ENSO phenomenon has been around for a very long time, many millions of years at the very least. It was once thought that the Pliocene (around 2-5 million years ago) saw a permanent El Nino, but recent research indicates that our friend ENSO was still doing it's thing then too, and may in fact stretch back tens of millions of years.

    Current global warming on the other hand has only been around a short time - since the start of the Industrial Revolution (around 1750), a time when humans started to fundamentally alter the composition of the ocean and atmosphere through the burning of fossil fuels. All this manmade CO2 creates a small but persistent annual warming trend.

    Prior to the Industrial Revolution i.e. the natural pristine climate would have been something like this:

    In the absence of any climatic 'nudge' the climate would not undergo any net long-term warming or cooling because ENSO (and the 11-year solar cycle) average out to zero.

    With increased concentrations of carbon dioxide in the atmosphere from fossil fuel burning (global warming) this changes things. That cyclic ENSO is now superimposed upon top of a rising trend.

    Of course in the real world these cycles are not regular as in these diagrams, that's just for illustrative purposes. That's how it might appear if we were to plot temperatures on a graph, but what we would actually experience are periods of slow or negligible global warming, followed by periods of rapid global warming (as the NASA scientists expect). So quick/slow/quick/slow..........and so on and so forth.

    Again, not every cycle will be the same, there is likely to be significant variability. This variability is apparent in every climate model run that I have ever seen. You may perhaps have seen it too, but may not have grasped its significance.

    Anyway hope this clears up your confusion. Current global warming intersperses periods of little warming with periods of rapid warming because the natural cool/warm oscillations are superimposed on a warming trend. At times it reinforces the warming trend (warm phase), and at other times it works against it (cool phase). This is nothing unexpected, however predicting the timing and intensity in well in advance is difficult. However as those eminent NASA scientists point out, the evidence strongly suggests a rapid global warming phase is near.
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  30. Rob@25

    Thanks you effort in detailing the explanation.

    Is it certain that the ENSO cycle and the warming trend are independent?

    For example - how well do we know that the heat energy tranferred to the atmosphere from the ocean during El Nino is equal to that returned to it during a La Nina?
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  31. Link needed for IanC's # 16.
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  32. OK, clicking on the image goes to of page you're linking to which is not helpful.

    But right click / copy image location works:

    It looks like an old but good NASA page that IanC found somehow.
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