What is the “pause” in global warming?

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A new paper (commentary) on the so-called “pause in global warming” puts it all together.

First let’s establish this as a starting point. When climate science contrarians refer to a “pause” or “hiatus” in global warming, they usually mean that the process of warming of the Earth’s surface caused by the human release of greenhouse gas is not a thing. They are usually implying, or overtly claiming, that the link between CO2 and other greenhouse gas pollutants and surface warming was never there to begin with, and previous warming, warming before “the pause,” was natural variation. Many even go so far as to claim that the Earth’s surface temperature will go down to levels seen decades ago.

“The Pause” is not, in their minds, a slowdown in the rate of warming. It is a disconnect, either there all along or produced somehow recently, between the physics of the greenhouse effect and reality.

Also, the evidence adduced for this “pause” is often bogus. Sometimes badly calibrated satellite data is used to show a flat Earth surface. Er, flat Earth surface temperature. Sometimes a line is drawn from an unusually warm, even under conditions of global warming, El Niño year, to later years, lately excluding record breaking recent warm years, in order to make the line flatter. So, that part of the denier pause is a different kind of lie. See this post and this post for recent research on this issue.

Having said all that, there have been frequent slowdowns and speed-ups in the rate of the planet’s surface warming throughout the entire instrumental record. (Even though the instrumental record begins in 1850 or 1880, depending on which data set you use, greenhouse gas pollution started before that, so some greenhouse warming has been happening all along).

Prior some date, like 1970 perhaps, the up and down variations in surface temperature has been a combination of natural variation and human caused variation, with both being strong factors. The human caused variation includes particulate pollution (from burning coal, mainly) which pushes the temperature down, and greenhouse gas release and its associated effects, which push the temperature up.

For the last third or so of the 20th century, through the present, while both natural and human-caused effects matter, the role of human effects has increased to be the dominant force in the overall trend. The natural variations continue to contribute to the shape of the curve, but this contribution is attenuated by the increased abundance of human generated greenhouse gas.

For the last few years, we have seen several research projects that look at the “pause.” Many of these projects helped to explain the slowdown by showing that it wasn’t really as much of a slowdown as previously thought. For example, some research showed that the surface warming in recent decades has been under-measured because the Arctic (and probably the interior of Africa) were getting warmer faster, compared to other regions, and those areas were under-sampled by the usual data sets. Also, heat has been moving in and out of the ocean all along, and that has had an effect on the surface temperaturews.

But even after accounting for all of these effects, there is still a slowdown.

John C. Fyfe, Gerald A. Meehl, Matthew H. England, Michael E. Mann, Benjamin D. Santer, Gregory M. Flato, Ed Hawkins, Nathan P. Gillett, Shang-Ping Xie, Yu Kosaka and Neil C. Swart have just published a commentary in Nature Climate Change called “Making sense of the early-2000s warming slowdown” that looks at what caused this partial flattening out of the upward trend in global surface temperatures.

Part of this investigation compares the earlier part of the 20th century, when there was a much more significant slowdown in warming, with the more recent slowdown. Fyfe et al note that there are two major contributors to variation in surface temperature aside from greenhouse gases. One is the abundance of aerosols, such as industrial pollution (more of a factor during the earlier hiatus) and the output of volcanoes (such as the 1991 eruption of Mount Pinatubo). The other is multi-decade scale variation in the interaction between the oceans and the atmosphere. The following figure compares the two periods of reduced rate of warming.

Screen Shot 2016-02-23 at 1.22.39 PM

As noted in the caption, the two periods are representations of how far off from expected (based on simple greenhouse warming) each period is. It happens that these two periods of slowdown in rate of warming are associated with the negative phase of a major ocean-atmosphere interaction, during which the ocean was eating up some of the extra heat, removing it from the atmosphere. The intervening period of increased rate of warming (from the mid 1970s to about 2000) is associated with a period when this system was in positive phase, putting heat out into the atmosphere. As I’ve noted before, the ocean, which takes up most of the global warming caused heat, is the dog, and the atmosphere is the tail. This is a graph of a dog wagging its tail.

It is not clear when the multi-decade scale ocean-atmosphere interactions will shift to a positive phase. If you look at just the raw numbers, it seems like this may have started a few years ago (around late 2013) but the index for this phenomenon varies enough (goes positive and negative and back over shorter time periods, briefly) that this is not certain. More recently, we have an El Nino causing the belching of heat form the ocean to the air, heating up the surface. This may or may not be related to the multi-decade pattern. Having said all that, we may be concerned that over the next ten years or so, starting about now, we will be in a positive phase during which the rate of warming will be accelerated. This may not be the case. Or it might be the case. No one is actually betting on this yet.

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34 thoughts on “What is the “pause” in global warming?

  1. I am very interested in trying to see what a full ocean cycle will look like. We only started getting global data (satellite) in 1979.

    We are a little over 1/2 way through a 60 year time period. 2039 is 60 years from 1979 – so we will know a lot more about temperature trends with 60 years of global data.

    Until then, we are still learning stuff everyday and we realize that we still don’t know very much about the climate.

    The stadium wave hypothesis indicates that we should be in a cooling phase until the 2030’s – so it will be interesting to see if we switch to a warming positive phase or stay with the more muted rise you show on your graph.

    Wouldn’t it be really interesting if we actually cooled for a decade or so!

    This is what science is all about.

    Making new observations and trying to figure out how they fit with our hypothesis (or not) – and making new ones which fit the actual observations.

    Lots of fun until at least 2038.

  2. it’s too bad the chart begins at 1880. have any studies filled in the blanks backwards from there? decades, at least, or better yet centuries? thanks.

  3. Since the stadium wave hypothesis was published, each year has been hotter than the year before it, with this year likely to be another. When should we expect this cooling to commence?

  4. This is what science is all about.

    Science is about repeating nonsense you got from reading contrarian blogs because it happens to agree with your prejudices?

  5. RickA’s craven broken record:

    No, no, don’t do anything! Just take a wait & see approach! We don’t know enough! We’ll know that AGW is going to be a disaster only after it’s already an irreversible disaster!

    Translation: Don’t do anything that will impact my precious, cherished lifestyle — let the people die, if that’s the risk. I don’t care about other human beings…

  6. In 2038 Rick A will state ‘… but thats only one 60 year cycle, we need to see at least 5 more cycles before we can see any ‘real trends’. Lots of fun until at least 2338.’

  7. Gosh, look at all of the times it “paused.” It’s almost as if there is natural variation in the physics involved; golly, it’s almost as if Denialists have no clue what they are talking about…..

  8. curiousaboutclimate #3:

    Maybe it already started?

    Maybe the “slowdown” is caused by a stadium wave, which will continue until the 2030’s?

    What is causing the “slowdown”?

    Now that people are admitting that there is one.

    It is not caused by emitting less CO2.

    I suppose it could be caused by less air pollution – but China is polluting the air more than ever.

    All I know is we don’t understand the climate yet – or we would be able to predict and explain the “slowdown”, or the warming from 1905 – 1945 or the MWP or the Roman warm period, etc.

  9. “[…] 2039 is 60 years from 1979 – so we will know a lot more about temperature trends with 60 years of global data. [….]”

    Er.. ah… no one has any global temperature data via satellites. You are, as always, confused.

    By the way, we already have about three billion years of data on Earth’s climate.

  10. Brainstorms:

    How many dead bodies have washed up on the shore from our 1C increase in temperatures from 1880 to present?

    I say zero.

    I suppose you will blame every death since 1880 on climate?

  11. “Until then, we are still learning stuff everyday and we realize that we still don’t know very much about the climate.”

    There he goes with his “we” again. Since “Ricka” does not know anything about human-caused climate change, therefore no one does.

  12. it’s almost as if Denialists have no clue what they are talking about

    It’s a natural feedback on their part: science ignorers like rickA have gotten so accustomed to the flat “x is not happening and is it not possible for y to cause it to happen”, stated without a bit of uncertainty, that they’ve come to view the fact that much of this work involves explaining and quantifying uncertainty as a flaw rather than a feature.

  13. “Wouldn’t it be really interesting if we actually cooled for a decade or so!”

    Yeah, a global disaster will certainly cause that, and be “really interesting.” A large meteorite strike that sends a hell of a lot of smoke, ash, and dirt into the stratosphere will cool the planet and be “really interesting.” Increasing SO2 into the atmosphere, killing many millions of more humans every year, would cool the planet and be “really interesting.”

    Anything that will cool the planet “for a decade or so” would be something to dread.

  14. How could it have already started when we just had the warmest year on record, and each year since 2011 has been warmer than the previous? If I recall, Curry’s hypothesis was that the cooling phase of the stadium wave started in 2012. Does the temperature evolution of the last 4 years support that hypothesis?

  15. “Making new observations and trying to figure out how they fit with our hypothesis (or not)….”

    Your cult has a dozen hypotheses, most of them mutually contradictory.

  16. The stadium wave hypothesis indicates that we should be in a cooling phase until the 2030’s….”

    Yeah, uh, er; when it starts to cool, do tell someone, m’kay?

  17. Yeah, I’m with desertphile. There needs to actually be a cooling phase in order for it to continue until whenever.

  18. The paper (pay-walled) is here. The abstract (available) is;

    It has been claimed that the early-2000s global warming slowdown or hiatus, characterized by a reduced rate of global surface warming, has been overstated, lacks sound scientific basis, or is unsupported by observations. The evidence presented here contradicts these claims.

    There is a blog post here by one of the authors, Ed Hawkins, who says that the paper is “mainly in response to Karl et al. and Lewandowsky et al….”, who try to argue that the pause (hiatus, slowdown, plateau, whatever) is not real. Many actual scientists actually working in climate science, on the other hand, think that is probably is, thus this paper.

  19. Maybe it already started ended?

    Now that people are admitting that there is was one.

    Ricka’s statements have an extraordinarily high error rate.

  20. RickA, if you’re having that much trouble understanding the abstract, maybe get some advice before throwing away US$18…

  21. Well I, for one, think Mann is a 100% dependable and trustable source, now that he is putting his name to a paper which says there is definitely a Hiatus (and therefore, obviously, he is also implying that global cooling is just around the corner).
    Clearly, Mann is telling us that all the models are wrong, as we always suspected.
    Obviously, if Mann says the Hiatus is real, that means all of global warming is a complete fraud and a scam.

    1. Craig Thomas: “Obviously, if Mann says the Hiatus is real, that means all of global warming is a complete fraud and a scam.”

      Now that Dr Mann has confessed, I wonder if Rafael Eduardo Cruz will invite him to testify in Congress.

  22. Delingpole is now reporting on this study at Breitbart. Apparently all AGW “conspirators” are being forced to concede that their skeptic adversaries are right and are turning on each other.

    Not sure if RickA has a history here, but his statement that the cooling phase may have already started seems like it could be a reference to, though the temperature is still increasing, the “cooling phase” is reducing the rate of increase. I guess I’m just not seeing here how he fits into the denialist camp if he agrees that CC is occurring and thinks it will increase at a greater in the future after temporary pressures downward are gone.

    1. Lord Palmerston: [climate bet web page]

      From the web page, not from Lord Palmerston, first paragraph: “It was 2007, at the height of the alarm over global warming. We could see the theory about carbon dioxide had no empirical evidence to back it, only a sensitivity calculation and computer models based on theory. Yet the hype was huge.”

      Gosh, let me see…..

      #1, the alarm is much greater now than it was in year 2007. The effects of human-caused warming of Earth are also much worse— an astounding amount of ice mass lost, and The Cold Blob “under” Greenland as the thermal halon “conveyor belt” slowed.

      #2: the “theory about carbon dioxide” is called “physics” and more specifically “chemistry,” and my year 1910 both classical physics and quantum physics explained how (and therefore why) increasing atmospheric CO2 has, is, and will increase global average temperature.

      #3: observation shows the “theory” (known laws of physics regarding atmospheric CO2) is 100% correct.

      #4: the hype, thankfully, is much, much larger.

      Also from the web page: “It is now widely acknowledged that there is a pause or hiatus in global warming….”

      I know of no scientists working in the related science venues, anywhere, ever, who have agreed there was or is a “pause” in Earth’s warming.

      I also find it amusing that the wager applies to how much Earth will warm due to human activities, and not the fact that it is warming.

  23. Nice in-group signalling that took up the entire first half of the article. It definitely builds an outsider’s confidence in your ability to report scientific findings in an unbiased way.
    And your lot wonder why the vast majority of people simply don’t care about this any more…

    1. echo: ” It definitely builds an outsider’s confidence in your ability to report scientific findings in an unbiased way.”

      Okay, I give up. Please explain how the bloody anal fuck it is possible to report science without bias? The WHOLE FUCKING POINT about science is that it is biased! If it is not biased, it isn’t science. Sheeeish.

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