The Atlantic Multidecadal Oscillation and the Temperature Record

  • In this post I compare the de-trended HadCRUT4 global temperature reconstruction with the Atlantic Multidecadal Oscillation index (AMO).
  • The AMO fluctuates between cold and warm phases on a quasi 66 year cycle, 33 years warming followed by 33 years cooling, and is modulated by strengthening and weakening of the Atlantic Meridional Overturning Circulation (AMOC) [1]. The AMO has been in warm phase since around 1995 with consequences for climate in the circum N Atlantic domain.
  • There is a high degree of co-variance with R^2 = 0.52, but with occasional periods where the AMO and HadCRUT4 are out of phase, for example in the 1950s (Figure 1). Fluctuations in AMOC and the AMO can explain much of but not all the cyclical variance in the global temperature record. Much of the global warming since 1850 also correlates with upwards trending North Atlantic sea surface temperatures (NA SSTs).
  • The AMO is now due to enter it’s cooling phase that may continue for 20 or more years. Global temperatures may therefore continue to trend sideways or down, unless greenhouse gas emissions have the power to overcome nature.

Figure 1 De-trended HadCRUT4 compared with the AMO index that is based on de-trended NA SSTs. AMO index from NOAA. (AMO unsmooth long)

All climate watchers should be familiar with the oscillating pattern of temperature change since 1850 (Figure 2). The temperature record fluctuates above and below the  trend line (linear regression). Subtracting the regression from the actual record de-trends the data and these residuals allow the pattern to be seen more clearly. A quasi 66 year long cycle emerges (Figure 3). I am certainly not the first person to observe this and to recognise that the distribution of residuals matches the Atlantic Multidecadal Oscillation (Figure 1) (R^2 = 0.52) e.g. [2].

Figure 2 HadCRUT4 temperature data oscillate around the liner regression (solid red line). Subtracting the linear regression from HadCRUT4 de-trends the data as shown in Figure 3.

Figure 3 Subtracting the linear regression from the actual HadCRUT4 data provides this distribution of residuals and the quasi 66 year cycle emerges. The dates for the peaks and troughs are labelled. Starting in 1878+33=1911+33=1944+32=1976+33=2009.

So why is any of this important? The answer lies in how this distribution of residuals matches the pattern of the Atlantic Multidecadal Oscillation (Figure 1). There is a stronger degree of co-variance than the healthy R^2 value of 0.52 suggests. There is a high level of correspondence between the major peaks and troughs. But also some periods where the AMO and HadCRUT4 are out of phase. This is not surprising since the AMO is not the only ocean cycle or the only factor influencing climate. But it does seem to be an important variable.


So what is the AMO and what does this correlation between the AMO and HadCRUT4 mean? NOAA have this interesting FAQ page on the AMO. A few selected quotes follow:

What is the AMO? The AMO is an ongoing series of long-duration changes in the sea surface temperature of the North Atlantic Ocean, with cool and warm phases that may last for 20-40 years at a time and a difference of about 1°F between extremes. These changes are natural and have been occurring for at least the last 1,000 years.

How much of the Atlantic are we talking about? Most of the Atlantic between the equator and Greenland changes in unison. Some area of the North Pacific also seem to be affected.

What are the impacts of the AMO? The AMO has affected air temperatures and rainfall over much of the Northern Hemisphere, in particular, North America and Europe. It is associated with changes in the frequency of North American droughts and is reflected in the frequency of severe Atlantic hurricanes. It alternately obscures and exaggerates the global increase in temperatures due to human-induced global warming.

How does the AMO affect rainfall and droughts? Recent research suggests that the AMO is related to the past occurrence of major droughts in the Midwest and the Southwest. When the AMO is in its warm phase, these droughts tend to be more frequent and/or severe (prolonged?). Vice-versa for negative AMO. Two of the most severe droughts of the 20th century occurred during the positive AMO between 1925 and 1965: The Dustbowl of the 1930s and the 1950s drought. Florida and the Pacific Northwest tend to be the opposite – warm AMO, more rainfall.

To summarise the informed opinion of Americas finest climate scientists working at NOAA. The AMO is a natural cycle. It affects rainfall patterns over the N hemisphere, including the frequency of severe hurricanes, and the occurrence of drought in the Midwest and Southwest that correlate with the warm phase of the AMO. The AMO shifted to warm phase around 1995 (Figure 1).

Figure 1 shows that the AMO can explain much of the structure in the temperature record. But can it explain the overall warming trend? NOAA also report the “raw” N Atlantic SST data (N. Atlantic SST averages, unsmoothed & not detrended 1856 to present) upon which the AMO index is based and these are plotted together with HadCRUT 4 in Figure 4. We see that from 1856 to 1972 there is very close agreement between the NA SSTs and HadCRUT4, but then the trends diverge. The most simple explanation is that the atmosphere is warming at twice the rate of the NA SST (0.51˚C v 0.26˚C per century). I do have an alternative explanation, but that is a story for another day or for the comments.

Figure 4 Comparison of North Atlantic SST with HadCRUT4.

The AMO and Global Temperatures

Why should the AMO show such a high degree of co-variance with global lower troposphere temperature reconstructions? At one level the explanation is simple. 71% of HadCRUT4 is based on SSTs and the temperature of the North Atlantic  is included in that data. But on the other hand, the North  Atlantic is only a small portion of global SSTs. The UK Met Office has just published a report on the impacts of ocean cycles on the climate system [1] (Big Changes Underway in the Climate System?), and they say this:

AMO variability is thought to be associated with the flow of water that carries heat northward within the North Atlantic Ocean, known as the Atlantic Meridional Overturning Circulation (AMOC; Knight et al. 2005). Variability in AMOC strength alters the amount of heat that is transported, in turn changing the average surface temperature of the North Atlantic Ocean (Gulev et al., 2013).

The AMO, therefore, is a reflection of the strength of the AMOC and since the AMOC is a part of the global conveyer belt of thermohaline circulation, if the AMOC changes pace one can presume that the flow of thermohaline circulation must also change pace with knock on effects to the climate system in multiple ways. In the North Atlantic, a more active AMOC transports more heat to higher latitudes and with it more water vapour, hence warmer and wetter climate. One can speculate that changes to the AMO and AMOC may also result in a change to the amount and distribution of global cloud cover. Juraj Vanovcan writing on WUWT [2] also observes a negative correlation with the Arctic Sea ice – no great surprise there.

When will the AMO revert back to its cold phase? Since the AMO is quasi cyclical, this is difficult to answer precisely, but the warm phase peak should have been around 2009 (Figure 3) and the cold phase trough is due around 2042. Between now and then, the N Atlantic should begin to cool and the Arctic sea ice begin to recover. If history repeats, a shift to the cooling phase of the AMO may see global surface temperatures trending sideways or down for another two decades or more. A look at current SSTs shows a large area of cool water stretching from Ireland to Newfoundland (Figure 5). This is something to watch in the months and years ahead.

Figure 5 SST anomalies for 17 September 2015. Does that large area of cool water in the N Atlantic portend a shift in the AMO towards its cool phase?

Concluding Comments

  • Quasi cyclical changes in the Atlantic Multidecadal Oscillation (AMO) correspond to quasi cyclical changes in global surface temperatures. The AMO is modulated by changes in the pace of the Atlantic Meridional Overturning Circulation (AMOC). All of these phenomena can be linked to cyclical changes in the pace of global thermo-haline circulation.
  • While it is difficult to predict, the AMO should be heading into its cooling leg (note that the cooling leg begins past the peak of the warm phase). The Met Office report [1] provides supporting evidence for this from multiple sources.
  • Both the US NOAA and UK Met Office now seem to be fully aware of the role played by natural cyclical changes in the oceans in modulating the decade scale cyclical climate change we observe on Earth. And yet both organisations seem content to mislead the public and politicians by seeking to explain all variations from the recent average at specific locations by means of anthropogenic global warming.

[1] UK MET Office Big Changes Underway in the Climate System?
[2] Juraj Vanovcan on WUWT European climate, Alpine glaciers and Arctic ice in relation to North Atlantic SST record.

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37 Responses to The Atlantic Multidecadal Oscillation and the Temperature Record

  1. Peter Lang says:

    Interesting. Thank you.

    Wyatt and Curry, 2014, “Stadium Waves” may be of interest:

    Citation: M.G. Wyatt and J.A. Curry, “Role for Eurasian Arctic shelf sea ice in a secularly varying hemispheric climate signal during the 20th century,” (Climate Dynamics, 2013)
    The full manuscript can be downloaded here [ stadium wave].

  2. The AMO also controls glacier advance and retreat in the Swiss Alps:

  3. clivebest says:

    The Atlantic circulation is more important than the Pacific because it moves water from the Northern to the Southern Hemisphere. Water sinking in the Arctic re-surfaces thousands of years later near Antarctica. The pump that drives the AMOC circulation is the Antarctic circumpolar wind.

  4. Hugh Sharman says:


    Another outstanding post. I don’t understand all the terminology nor in any detail, the science. But the correlations you show in Figure 1 seem startling relevant.

    I had already read the story and watched the YouTube at, attracted by the startling headline “The Hidden Meltdown of Greenland”, a recurring theme.

    It is the start of an investigation not the conclusion. My naive question is whether this is “unscientific” hype or serious science? It reads to me a bit like a grant application. Interesting none the less!

    Of course, all the ice on Greenland will not melt within the foreseeable future but the eastern seaboard of Greenland was flourishing forests far north as recently as the Eemian, only 130,000 years ago when the seawater was 5 meters higher than today and life flourished.

    I am generally frustrated by the lack of any satisfactory explanation, even curiosity, about why the previous 4 interglacials were so much warmer than our present, brief existence between ice ages among the climate sceptics like most readers of this blog and the AGW alarmists.

    Any chance that some better informed reader than I might contribute to such an answer on “Energy Matters”?

    • Euan Mearns says:

      Hugh, glaciers melt during inter-glacials. I don’t know the answer to your question about the temperature optima of inter-glacials. The curious thing about the Holocene is “the plateau” that provided incredibly stable climatic conditions compared with the past and perhaps allowed the human race to flourish. Maybe this has caused invariant climate to be embedded in the DNA of Mann.

      In prior interglacials things just continued to get warmer before suddenly deciding it was time to start getting colder again. This time we have had a long pause. Maybe we will start to get much warmer, as before, or fall off the edge of the plateau.

    • Euan Mearns says:

      Here is the correlation between Arctic Sea ice and the NA SST from WUWT. I’m pretty sure there will be a correlation between Arctic Sea ice and Greenland ice mass. Salinity distribution in the Arctic oceans is a vital variable. Amongst other thing this may control where the AMOC sinks.

    • Javier says:

      Hugh Sharman,

      That is an easy one. What gives the temperature differential to interglacials is the combination of precession (wobble of the Earth axis) and obliquity (tilt of the Earth axis). Two factors determine this temperature differential:

      1) How close are the precession and obliquity peaks. If both are very close or coincident in time you get a warmer but shorter interglacial. If both are separated you get a cooler longer interglacial. Our present interglacial had precession peak at -10 kyr BP and obliquity peak at -9 kyr BP so they were pretty close, however the second factor is also important:

      2) The amplitude of the precession peak. Climatic precession is regulated by eccentricity, and eccentricity has a main cycle of 413 Kyr were the Earth’s orbit goes from maximal ellipticity (e = 0.05) to almost circularity (e = 0.002). Currently eccentricity is very low (e = 0.015) and going towards a 413 kyr minimum in about 25 Kyr time, so climatic precession has a very low amplitude. Instead of going from -0.05 to +0.05 it only goes from -0.02 to +0.02. A low amplitude precession peak is in my opinion the main reason behind our interglacial being less warm than Eemian.

      These variable orbital factors make very difficult to compare interglacials, as each tends to have a different orbital signature. The closest analog to Holocene on record is Marine Isotope Stage 19 (MIS 19), that took place 777 kyr ago. It lasted about 1,500 years longer than the Holocene has lasted so far, before what is called glacial inception.

  5. Euan Mearns says:

    This is a section I deleted from the original post (Figures renumbered). The bottom line is that with the exception of a 0.24˚C step change in 1972, HadCRUT4 follows the NA STT very closely. All of the difference in gradient between the NA SST and HadCRUT4 comes down to that one small step.

    Figure 1 Comparison of North Atlantic SST with HadCRUT4.

    Figure 2 This chart shows the NA STT (average temperature) minus HadCRUT4 (temperature anomaly). There is a clear divide in 1972 where HadCRUT4 steps up relatively to NA SST causing the difference to step down. The regressions through the two time periods have identical gradients consistent with the atmosphere warming 0.08˚C more rapidly than the N Atlantic surface water. The difference is clearly trivial.

    Figure 1 shows that the North Atlantic (NA) SST and HadCRUT4 are very closely alined from 1856 to about 1972. But then there is a divergence. To be more precise, there is a step change of 0.24˚C. HadCRUT4 should have declined further than it did in the mid 1970s if it continued to follow the NA SST precisely, but for some reason it did not. One simplistic interpretation of the data is that HadCRUT4 is warming at 0.51˚C per century, twice the rate of the NA SST that is warming at 0.26˚C per century. But all of that difference comes out of the single step change described above.

    Figure 2 plots the difference between the NA SST and HadCRUT4 and illustrates the step change in 1972. A regression through the 1856 to 1971 data has a gradient of -0.08 ˚C per century. That is the rate that the atmosphere is warming more rapidly than the NA SST. A regression through the 1972 to 2014 data has the identical gradient. I cannot offer an explanation for the step in 1972, but setting that aside ALL of the variance in HadCRUT4 can be explained by the NA SST.

    • A C Osborn says:

      The problem is you have fallen in to the same trap as every other scientist or Analyst working with current Temperature series.
      They do NOT represent History, they have all been modified to remove many of the fluctuations in Temperatures that Historical Documents say happened, 1930s heat, 1970s cooling etc.
      Therefore you can’t really expect to get the correct correlations.

  6. Flocard says:

    I notice this sentence in your text
    “If history repeats, a shift to the cooling phase of the AMO may see global surface temperatures trending sideways or down for another two decades or more.”
    which I think refers to the “temperature hiatus” discussed .since the beginning of this century
    On this specific subject, what do you make of this recently published work from Stanford statisticians :

    • Euan Mearns says:

      Hubert, I don’t think much of it at all. For example:

      Faulty ocean buoys
      The Stanford group’s findings are the latest in a growing series of papers to cast doubt on the existence of a hiatus. Another study, led by Thomas Karl, the director of the National Centers for Environmental Information of the National Oceanic and Atmospheric Administration (NOAA) and published recently in the journal Science, found that many of the ocean buoys used to measure sea surface temperatures during the past couple of decades gave cooler readings than measurements gathered from ships. The NOAA group suggested that by correcting the buoy measurements, the hiatus signal disappears.

      Perhaps its the ships that are running warm and should be corrected to the buoys? Curiously over the oceans the SSTs agree with the satellites.

      And in the case of HadCRUT they got rid of the pause by changing the data.

      Everyone should read the Met Office post I link to above. Typically schizophrenic, they seem to be laying the ground work to prepare everyone for the pause to continue. Pause and cooling caused by natural cycles but all warming caused by CO2. It is a scientifically hopeless position to be in.

  7. Elvis says:

    Interesting post, Euan. The correlation in figure 1 is striking, but the graph is the product of assuming a long term linear tread that existed in 1850 as it does unchanged today. This is confusing, as the GHG concentration and hence known forcing in 1850 was quite different from today’s, which makes it unlikely that the same trend existed back then.

    You say that NOAA and the MO are misleading the public but it seems that what needs explaining is the trend, not the wobbles around the trend. The AMO, an oscillation, cannot explain a trend.

    If you were to use a non-linear trend that better reflected known forcing and change points the extend of the correlation of figure 1 would be much diminished. NOAA/MO would then still have to explain the recent trend.

    • Euan Mearns says:

      Elvis, this is fair and legitimate commentary. I’d point out that the UK Met office has either promoted or not refuted that all “warm wet weather” events in the UK in recent years are down to “global warming”. Now they’re saying it is down to the warm phase of the AMO. NOAA now proclaiming that hurricane intensity is also linked to the AMO. So I think they have a lot to answer.

      I would refute your assertion that the Manmade forcing is known but accept your broader point that a curved fit may be more appropriate and we may find that combined AMO + CO2 gives a better correlation. This is a bit beyond my skills but I’ll see if Clive Best is interested to look into this. Looking just at radiative forcing of CO2 without feedbacks I’d imagine the effect will be tiny.

      I’ve been wanting to post this chart (also removed from original post) based on idea from Richard Lindzen. Natural climate change to the left and manmade to the right. It is relevant to your comment.

      • Elvis says:

        “we may find that combined AMO + CO2 gives a better correlation”

        Entirely possible, indeed even probable. To deny either AMO or CO2 any role in the temperature progression would require strong evidence. Lindzen’s chart is food for thought. It would be more striking if it stopped in 1998 🙂 A Google image search for that chart says “crescita demografica italia” is the best guess – do you have the source by chance?

        ACOsborn, sorry, but I don’t follow your question.

        • Euan Mearns says:

          Well I made the chart, the two y-axes are same scale but offset by 0.3˚C. And yes, if you were to look for any evidence of non-natural climate signal it would be in the “high plateau” post-1998. Perhaps temperatures should be on the way down? But its too early to say. The Met Office in their report had some interesting comments about detection of changing deep ocean currents – but I need to re-read.

    • A C Osborn says:

      Please explain the “known forcings” that brought about the end of the last Ice Age and the mini Ice Age and then apply them to post 1850 to present.
      Because warming did not start in 1850, or later.

  8. Ted says:

    I understand that figures 1 and 3 are detrended but they highlight the year 1878. If memory serves, 1878 was the hottest summer on record in Australia, and right around the other side of the globe, it was by far the warmest winter ever on record here in Minnesota (temperature records back to 1820 at Fort Snelling). What caused such warm weather globally right at the end of the little ice age?

    • Euan Mearns says:

      Ted, I can but guess a large El Niño. We have a jig saw where the big picture and the shape and size of the pieces are always changing. Sometimes stress builds up along the edge of some of the pieces which then gets released to relieve the thermal stress and restore dynamic thermal equilibrium. A geologists view 😉

      • Ted says:

        According to the U of Minnesota/DNR climate website it was indeed an El Niño year. The 1877-78 Dec-Feb average temperature F was 26.0 degrees The second warmest winter in Minnesota was also an El Niño year, 1997-98, where the average Dec-Feb temperature F was 21.9 degrees.

  9. Travis Casey says:

    Please correct me if I am wrong, but in the first graph, to me it shows where Hadcrut has cooled the Dustbowl years to advance their narrative.

  10. Owen says:

    The Irish Met office issued this statement last month in relation to the AMO :

    “The Atlantic multidecadal oscillation (AMO) which relates to the North Atlantic sea surface temperatures, explains over 90% of the pronounced decadal variation in annual land temperatures and summer precipitation- Met Eireann, 2015.”

    The phases of the AMO and temp in Ireland seem to be a perfect fit – see graph here :

    Figure 5 is very interesting. Is that large body of cool water common at this time of the year ?
    How does it compare with previous years ?

  11. Javier says:

    Two things of possible interest to you Euan,

    First, the North Atlantic has been cooling significantly since 2007, as the following graph from climate4you (National Oceanographic Data Center) shows:

    This is why scientists know that AMO has turned down. There is simply no way that Western Europe and Eastern US can be warming while ocean temperatures are dropping like that. All this talk about the oceans storing the heat is nonsense. North Atlantic sea surface summer temperatures are the best proxy record for obliquity induced interglacials as recorded by foramnifers in oceanic sediments. Most of the determinant climatic action of the planet takes place in the Atlantic due to continental disposition.

    Second, you might find this article interesting:
    Evidence for external forcing of the Atlantic Multidecadal Oscillation since termination of the Little Ice Age.

    AMO does not determine anything and is not the cause of anything, as it is only a temperature record. It is likely to be the result of the interplay of several causes, from trade winds and solar cycles to lunisolar tidal cycles with cloud changes thrown in for good measure. In my opinion what drives all these causes is the temperature gradient between tropics and polar regions. When the gradient gets too large the cooling mode is activated, AMOC strengthens and the world warms as the heat is transferred toward the poles. When the gradient is reduced the cooling mode is deactivated, AMOC weakens and the world cools (or doesn’t warm). This fully explains the detrended natural variability. The long term trend is mainly explained by the millennial cycle that bottomed during LIA. It is discussed all over the literature and in my opinion has two components, one solar with cycles of ~1,000 and ~2,200 years and one lunisolar tidal with cycles of ~1,500 years. CO2 contributes to warming by reducing the cooling when the Earth should be cooling as we discussed in the “The Diverging Surface Thermometer and Satellite Temperature Records Again” post of last week.

  12. I ran some empirical models some years ago in an attempt to segregate the impacts of ocean oscillations and greenhouse gases on the global air temperature record in different latitude bands. According to my results the AMO has a strong positive impact on temperature at high northern latitudes, but it decreases rapidly towards the Equator and goes negative in the S. Hemisphere.

  13. I haven’t had time to look at this in detail but, at first glance, I have to wonder about the first graph. It’s been done in a way to make it look like the AMO could account for almost all of the warming periods, most of the time. But one is an index based on detrended data and another is a detrended measure of temperature anomalies. What if you used an entirely different scale for the AMO index? Would it look a clear then? But global temperatures are influenced by all sorts of things (other oscillations, volcanic activities, greenhouse gases, etc.), so, clearly, the AMO is only one factor among many – scaling graphs to show something else isn’t particularly objective. As the AMO is an oscillation, I can’t see that it do anything other than add some oscillations to a trend – or is that what the first graph is actually showing? If so, then, so what?

    • Euan Mearns says:

      OK, so I decided to approve this comment. The 2 Y-axes scales on Figure 1 are scaled exactly the same. I am assuming that the AMO index is in ˚C since it based on SSTs measured in degrees centigrade. I’m also guessing that it is calculated in the same way as my de-trended HadCRUT4. And so as fas as I know I am plotting derivatives of two separate temperature series at exactly the same scale and you are accusing me of lacking objectivity.

      And I also say this:

      Fluctuations in AMOC and the AMO can explain much of but not all the cyclical variance in the global temperature record.

      And a quote from you:

      As the AMO is an oscillation, I can’t see that it do anything other than add some oscillations to a trend – or is that what the first graph is actually showing? If so, then, so what?

      Well if you’d taken time to look at Figure 4 you’d have observed that the NA SSTs have a gradient running through them, so its not just oscillations, its oscillations going upwards. And if you had an ounce of knowledge or understanding you’d realise that the last up leg, if caused to “large extent” by the AMO, then it is caused to much “lesser” extent by CO2.

      I’m afraid I don’t have time to waste on Green Trolls. You are here to preach and mislead. I’d like to think my lap top has now become adept at recognising Green BS. But just in case I have now put you to moderation. Comments with merit will be published. But misleading BS like this one won’t be.

      • Many apologies, Euan. I did rush that out before looking at your post in detail and that was wrong of me. I did try to find the units on the AMOC index before posting but couldn’t but should have considered more before posting.

  14. Interesting post from Tamino that kind of overlaps with this post and some earlier ones.

    • Euan Mearns says:

      Mike, your comments are for some reason being sent to moderation. I haven’t placed you on moderation and so cannot undo this. I didn’t approve your prior comment since it was totally devoid of merit. This one is really not much better.

      Here’s the data from RSS, the satellite data that deniers seem to like best because it shows the least warming:

      If you are reading and appreciating prose like this then I respectfully suggest there is something wrong with you, and all others like you and you should perhaps seek help.

      There’s so much wrong with the article you link to I don’t know where to start and I don’t have time to go into the detail.

    • Euan Mearns says:

      Here’s one of Tamino’s charts, allegedly correcting GISS LOTI for the effect of el Niño index, solar variance and aerosols. So what remains is a residual to be explained by other forcing.

      And here’s what he says:

      If you compare this with the first graph, you’ll see that the temperature trend is pretty much the same: steady increase from 1970 up to the present. However, the year-to-year fluctuations are reduced, which makes the steady trend even clearer than it was before. It also makes any talk of a so-called “pause” in global warming, look ridiculous. But then, such talk is ridiculous.

      Plotting a residual and claiming it to show global warming is simply ridiculous. What he wants to suggest is that CO2 forcing has continued underneath the natural variability.

      So we have a residual 0.7˚C to be explained by some other forcing. And the AMO index / NA SSTs just happen to have increased that much in that time frame (my Figures 1 and 4). Tamino needs to explain why he includes the el Niño, but not the AMO in his corrections. Doesn’t seem very objective to me!

      • Euan Mearns says:

        And just to hamer the point home, the chart above is the final up leg of an oscillation. And here’s what you said in an earlier comment:

        As the AMO is an oscillation, I can’t see that it do anything other than add some oscillations to a trend – or is that what the first graph is actually showing? If so, then, so what?

      • Not sure why it is ridiculous to claim that the residual temperature, that is, the temperature after subtracting the effect of some major natural (non-human caused) forcings, shows global warming, since it actually does.

        Your figure 1 doesn’t show a long term rise in the AMOC (it just shows oscillations about zero), though figure 4 does show about a 0.4C rise, on the trend line. However, I’m not sure why even this amount can be regarded as “natural” if ocean heat content and SSTs are rising due to human emitted greenhouse gases. Surely we’d expect such a rise? Also, you seem to be suggesting that the long term rise of SSTs in one ocean basin overwhelms all other surface temperature measurements, across the glob. Why would a rise of 0.4C (or even 0.7C) in one area of the globe account for 0.7C rise in the residual global surface temperature? Indeed, you stated in your post that one possible reason for the divergence (and I see many smaller period divergences in figure 4) is that global temperatures are rising twice as fast as NA SSTs. We also know that one smaller area of the NA is definitely cooling, rather than warming (possibly indicating the possibility of a large weakening of the Gulf Stream).

        • Euan Mearns says:

          Not sure why it is ridiculous to claim that the residual temperature, that is, the temperature after subtracting the effect of some major natural (non-human caused) forcings, shows global warming, since it actually does.

          Mike, I cannot help you. For example, the minute you subtract certain factors from the global whole the residual is no longer global. And if you close read my post you’ll find that most of the points you raise are covered.

          • the minute you subtract certain factors from the global whole the residual is no longer global

            Eh? I don’t see why. The total global temperature is calculated from multiple measuring points and include all natural factors. If it is global, at that point, then it is still global when you extract the global impact of various natural factors, since what is left is the global effect of human emissions plus other factors that haven’t yet been calculated. It is still global.

            I don’t think you covered all of the points I raised and I read your post several times. But, of course, it’s your prerogative to answer or not.

          • Euan Mearns says:

            Mike, The Earth is no longer The Earth if you take away the oceans, the continental crust and the core. It becomes a depleted residual that does not represent the whole.

            Would you care to explain to us what you believe the Tamino chart I posted here titled “NASA GISS” actually shows.

  15. Luís says:

    The obvious question is: how does NA SST correlates with HadCRUT3?


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